Removed openssl, and curl, and added mbedded tls.curl-removal

Almost fully removed curl, needs more testing.

Fixed most issues, now trying to cross compile.

Fix?

Sigh.

1 files changed, 4545 insertions, 0 deletions

diff --git a/lib/mbedtls-2.27.0/library/ssl_cli.c b/lib/mbedtls-2.27.0/library/ssl_cli.c
new file mode 100644
index 0000000..f49178c
--- /dev/null
+++ b/lib/mbedtls-2.27.0/library/ssl_cli.c
@@ -0,0 +1,4545 @@
+/*
+ *  SSLv3/TLSv1 client-side functions
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+#include "common.h"
+
+#if defined(MBEDTLS_SSL_CLI_C)
+
+#if defined(MBEDTLS_PLATFORM_C)
+#include "mbedtls/platform.h"
+#else
+#include <stdlib.h>
+#define mbedtls_calloc    calloc
+#define mbedtls_free      free
+#endif
+
+#include "mbedtls/ssl.h"
+#include "mbedtls/ssl_internal.h"
+#include "mbedtls/debug.h"
+#include "mbedtls/error.h"
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+#include "mbedtls/psa_util.h"
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+#include <string.h>
+
+#include <stdint.h>
+
+#if defined(MBEDTLS_HAVE_TIME)
+#include "mbedtls/platform_time.h"
+#endif
+
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+#include "mbedtls/platform_util.h"
+#endif
+
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+static int ssl_conf_has_static_psk( mbedtls_ssl_config const *conf )
+{
+    if( conf->psk_identity     == NULL ||
+        conf->psk_identity_len == 0     )
+    {
+        return( 0 );
+    }
+
+    if( conf->psk != NULL && conf->psk_len != 0 )
+        return( 1 );
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    if( ! mbedtls_svc_key_id_is_null( conf->psk_opaque ) )
+        return( 1 );
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+    return( 0 );
+}
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+static int ssl_conf_has_static_raw_psk( mbedtls_ssl_config const *conf )
+{
+    if( conf->psk_identity     == NULL ||
+        conf->psk_identity_len == 0     )
+    {
+        return( 0 );
+    }
+
+    if( conf->psk != NULL && conf->psk_len != 0 )
+        return( 1 );
+
+    return( 0 );
+}
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
+
+#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
+static int ssl_write_hostname_ext( mbedtls_ssl_context *ssl,
+                                   unsigned char *buf,
+                                   const unsigned char *end,
+                                   size_t *olen )
+{
+    unsigned char *p = buf;
+    size_t hostname_len;
+
+    *olen = 0;
+
+    if( ssl->hostname == NULL )
+        return( 0 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3,
+        ( "client hello, adding server name extension: %s",
+          ssl->hostname ) );
+
+    hostname_len = strlen( ssl->hostname );
+
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, hostname_len + 9 );
+
+    /*
+     * Sect. 3, RFC 6066 (TLS Extensions Definitions)
+     *
+     * In order to provide any of the server names, clients MAY include an
+     * extension of type "server_name" in the (extended) client hello. The
+     * "extension_data" field of this extension SHALL contain
+     * "ServerNameList" where:
+     *
+     * struct {
+     *     NameType name_type;
+     *     select (name_type) {
+     *         case host_name: HostName;
+     *     } name;
+     * } ServerName;
+     *
+     * enum {
+     *     host_name(0), (255)
+     * } NameType;
+     *
+     * opaque HostName<1..2^16-1>;
+     *
+     * struct {
+     *     ServerName server_name_list<1..2^16-1>
+     * } ServerNameList;
+     *
+     */
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SERVERNAME >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SERVERNAME      ) & 0xFF );
+
+    *p++ = (unsigned char)( ( (hostname_len + 5) >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( (hostname_len + 5)      ) & 0xFF );
+
+    *p++ = (unsigned char)( ( (hostname_len + 3) >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( (hostname_len + 3)      ) & 0xFF );
+
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SERVERNAME_HOSTNAME ) & 0xFF );
+    *p++ = (unsigned char)( ( hostname_len >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( hostname_len      ) & 0xFF );
+
+    memcpy( p, ssl->hostname, hostname_len );
+
+    *olen = hostname_len + 9;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
+
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+static int ssl_write_renegotiation_ext( mbedtls_ssl_context *ssl,
+                                        unsigned char *buf,
+                                        const unsigned char *end,
+                                        size_t *olen )
+{
+    unsigned char *p = buf;
+
+    *olen = 0;
+
+    /* We're always including an TLS_EMPTY_RENEGOTIATION_INFO_SCSV in the
+     * initial ClientHello, in which case also adding the renegotiation
+     * info extension is NOT RECOMMENDED as per RFC 5746 Section 3.4. */
+    if( ssl->renego_status != MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS )
+        return( 0 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3,
+        ( "client hello, adding renegotiation extension" ) );
+
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 5 + ssl->verify_data_len );
+
+    /*
+     * Secure renegotiation
+     */
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO >> 8 )
+                            & 0xFF );
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO      )
+                            & 0xFF );
+
+    *p++ = 0x00;
+    *p++ = ( ssl->verify_data_len + 1 ) & 0xFF;
+    *p++ = ssl->verify_data_len & 0xFF;
+
+    memcpy( p, ssl->own_verify_data, ssl->verify_data_len );
+
+    *olen = 5 + ssl->verify_data_len;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_RENEGOTIATION */
+
+/*
+ * Only if we handle at least one key exchange that needs signatures.
+ */
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
+    defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
+static int ssl_write_signature_algorithms_ext( mbedtls_ssl_context *ssl,
+                                               unsigned char *buf,
+                                               const unsigned char *end,
+                                               size_t *olen )
+{
+    unsigned char *p = buf;
+    size_t sig_alg_len = 0;
+    const int *md;
+
+#if defined(MBEDTLS_RSA_C) || defined(MBEDTLS_ECDSA_C)
+    unsigned char *sig_alg_list = buf + 6;
+#endif
+
+    *olen = 0;
+
+    if( ssl->conf->max_minor_ver != MBEDTLS_SSL_MINOR_VERSION_3 )
+        return( 0 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3,
+        ( "client hello, adding signature_algorithms extension" ) );
+
+    if( ssl->conf->sig_hashes == NULL )
+        return( MBEDTLS_ERR_SSL_BAD_CONFIG );
+
+    for( md = ssl->conf->sig_hashes; *md != MBEDTLS_MD_NONE; md++ )
+    {
+#if defined(MBEDTLS_ECDSA_C)
+        sig_alg_len += 2;
+#endif
+#if defined(MBEDTLS_RSA_C)
+        sig_alg_len += 2;
+#endif
+        if( sig_alg_len > MBEDTLS_SSL_MAX_SIG_HASH_ALG_LIST_LEN )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 3,
+                ( "length in bytes of sig-hash-alg extension too big" ) );
+            return( MBEDTLS_ERR_SSL_BAD_CONFIG );
+        }
+    }
+
+    /* Empty signature algorithms list, this is a configuration error. */
+    if( sig_alg_len == 0 )
+        return( MBEDTLS_ERR_SSL_BAD_CONFIG );
+
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, sig_alg_len + 6 );
+
+    /*
+     * Prepare signature_algorithms extension (TLS 1.2)
+     */
+    sig_alg_len = 0;
+
+    for( md = ssl->conf->sig_hashes; *md != MBEDTLS_MD_NONE; md++ )
+    {
+#if defined(MBEDTLS_ECDSA_C)
+        sig_alg_list[sig_alg_len++] = mbedtls_ssl_hash_from_md_alg( *md );
+        sig_alg_list[sig_alg_len++] = MBEDTLS_SSL_SIG_ECDSA;
+#endif
+#if defined(MBEDTLS_RSA_C)
+        sig_alg_list[sig_alg_len++] = mbedtls_ssl_hash_from_md_alg( *md );
+        sig_alg_list[sig_alg_len++] = MBEDTLS_SSL_SIG_RSA;
+#endif
+    }
+
+    /*
+     * enum {
+     *     none(0), md5(1), sha1(2), sha224(3), sha256(4), sha384(5),
+     *     sha512(6), (255)
+     * } HashAlgorithm;
+     *
+     * enum { anonymous(0), rsa(1), dsa(2), ecdsa(3), (255) }
+     *   SignatureAlgorithm;
+     *
+     * struct {
+     *     HashAlgorithm hash;
+     *     SignatureAlgorithm signature;
+     * } SignatureAndHashAlgorithm;
+     *
+     * SignatureAndHashAlgorithm
+     *   supported_signature_algorithms<2..2^16-2>;
+     */
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SIG_ALG >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SIG_ALG      ) & 0xFF );
+
+    *p++ = (unsigned char)( ( ( sig_alg_len + 2 ) >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( ( sig_alg_len + 2 )      ) & 0xFF );
+
+    *p++ = (unsigned char)( ( sig_alg_len >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( sig_alg_len      ) & 0xFF );
+
+    *olen = 6 + sig_alg_len;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 &&
+          MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
+
+#if defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C) || \
+    defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+static int ssl_write_supported_elliptic_curves_ext( mbedtls_ssl_context *ssl,
+                                                    unsigned char *buf,
+                                                    const unsigned char *end,
+                                                    size_t *olen )
+{
+    unsigned char *p = buf;
+    unsigned char *elliptic_curve_list = p + 6;
+    size_t elliptic_curve_len = 0;
+    const mbedtls_ecp_curve_info *info;
+    const mbedtls_ecp_group_id *grp_id;
+
+    *olen = 0;
+
+    MBEDTLS_SSL_DEBUG_MSG( 3,
+        ( "client hello, adding supported_elliptic_curves extension" ) );
+
+    if( ssl->conf->curve_list == NULL )
+        return( MBEDTLS_ERR_SSL_BAD_CONFIG );
+
+    for( grp_id = ssl->conf->curve_list;
+         *grp_id != MBEDTLS_ECP_DP_NONE;
+         grp_id++ )
+    {
+        info = mbedtls_ecp_curve_info_from_grp_id( *grp_id );
+        if( info == NULL )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1,
+                ( "invalid curve in ssl configuration" ) );
+            return( MBEDTLS_ERR_SSL_BAD_CONFIG );
+        }
+        elliptic_curve_len += 2;
+
+        if( elliptic_curve_len > MBEDTLS_SSL_MAX_CURVE_LIST_LEN )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 3,
+                ( "malformed supported_elliptic_curves extension in config" ) );
+            return( MBEDTLS_ERR_SSL_BAD_CONFIG );
+        }
+    }
+
+    /* Empty elliptic curve list, this is a configuration error. */
+    if( elliptic_curve_len == 0 )
+        return( MBEDTLS_ERR_SSL_BAD_CONFIG );
+
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 + elliptic_curve_len );
+
+    elliptic_curve_len = 0;
+
+    for( grp_id = ssl->conf->curve_list;
+         *grp_id != MBEDTLS_ECP_DP_NONE;
+         grp_id++ )
+    {
+        info = mbedtls_ecp_curve_info_from_grp_id( *grp_id );
+        elliptic_curve_list[elliptic_curve_len++] = info->tls_id >> 8;
+        elliptic_curve_list[elliptic_curve_len++] = info->tls_id & 0xFF;
+    }
+
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES >> 8 )
+                            & 0xFF );
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES      )
+                            & 0xFF );
+
+    *p++ = (unsigned char)( ( ( elliptic_curve_len + 2 ) >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( ( elliptic_curve_len + 2 )      ) & 0xFF );
+
+    *p++ = (unsigned char)( ( ( elliptic_curve_len     ) >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( ( elliptic_curve_len     )      ) & 0xFF );
+
+    *olen = 6 + elliptic_curve_len;
+
+    return( 0 );
+}
+
+static int ssl_write_supported_point_formats_ext( mbedtls_ssl_context *ssl,
+                                                  unsigned char *buf,
+                                                  const unsigned char *end,
+                                                  size_t *olen )
+{
+    unsigned char *p = buf;
+    (void) ssl; /* ssl used for debugging only */
+
+    *olen = 0;
+
+    MBEDTLS_SSL_DEBUG_MSG( 3,
+        ( "client hello, adding supported_point_formats extension" ) );
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 );
+
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS >> 8 )
+                            & 0xFF );
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS      )
+                            & 0xFF );
+
+    *p++ = 0x00;
+    *p++ = 2;
+
+    *p++ = 1;
+    *p++ = MBEDTLS_ECP_PF_UNCOMPRESSED;
+
+    *olen = 6;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_ECDH_C || MBEDTLS_ECDSA_C ||
+          MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */
+
+#if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+static int ssl_write_ecjpake_kkpp_ext( mbedtls_ssl_context *ssl,
+                                       unsigned char *buf,
+                                       const unsigned char *end,
+                                       size_t *olen )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    unsigned char *p = buf;
+    size_t kkpp_len;
+
+    *olen = 0;
+
+    /* Skip costly extension if we can't use EC J-PAKE anyway */
+    if( mbedtls_ecjpake_check( &ssl->handshake->ecjpake_ctx ) != 0 )
+        return( 0 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3,
+        ( "client hello, adding ecjpake_kkpp extension" ) );
+
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
+
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ECJPAKE_KKPP >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ECJPAKE_KKPP      ) & 0xFF );
+
+    /*
+     * We may need to send ClientHello multiple times for Hello verification.
+     * We don't want to compute fresh values every time (both for performance
+     * and consistency reasons), so cache the extension content.
+     */
+    if( ssl->handshake->ecjpake_cache == NULL ||
+        ssl->handshake->ecjpake_cache_len == 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "generating new ecjpake parameters" ) );
+
+        ret = mbedtls_ecjpake_write_round_one( &ssl->handshake->ecjpake_ctx,
+                                               p + 2, end - p - 2, &kkpp_len,
+                                               ssl->conf->f_rng, ssl->conf->p_rng );
+        if( ret != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1 ,
+                "mbedtls_ecjpake_write_round_one", ret );
+            return( ret );
+        }
+
+        ssl->handshake->ecjpake_cache = mbedtls_calloc( 1, kkpp_len );
+        if( ssl->handshake->ecjpake_cache == NULL )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "allocation failed" ) );
+            return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+        }
+
+        memcpy( ssl->handshake->ecjpake_cache, p + 2, kkpp_len );
+        ssl->handshake->ecjpake_cache_len = kkpp_len;
+    }
+    else
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "re-using cached ecjpake parameters" ) );
+
+        kkpp_len = ssl->handshake->ecjpake_cache_len;
+        MBEDTLS_SSL_CHK_BUF_PTR( p + 2, end, kkpp_len );
+
+        memcpy( p + 2, ssl->handshake->ecjpake_cache, kkpp_len );
+    }
+
+    *p++ = (unsigned char)( ( kkpp_len >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( kkpp_len      ) & 0xFF );
+
+    *olen = kkpp_len + 4;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */
+
+#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
+static int ssl_write_cid_ext( mbedtls_ssl_context *ssl,
+                              unsigned char *buf,
+                              const unsigned char *end,
+                              size_t *olen )
+{
+    unsigned char *p = buf;
+    size_t ext_len;
+
+    /*
+     * Quoting draft-ietf-tls-dtls-connection-id-05
+     * https://tools.ietf.org/html/draft-ietf-tls-dtls-connection-id-05
+     *
+     *   struct {
+     *      opaque cid<0..2^8-1>;
+     *   } ConnectionId;
+    */
+
+    *olen = 0;
+    if( ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM ||
+        ssl->negotiate_cid == MBEDTLS_SSL_CID_DISABLED )
+    {
+        return( 0 );
+    }
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, adding CID extension" ) );
+
+    /* ssl->own_cid_len is at most MBEDTLS_SSL_CID_IN_LEN_MAX
+     * which is at most 255, so the increment cannot overflow. */
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, (unsigned)( ssl->own_cid_len + 5 ) );
+
+    /* Add extension ID + size */
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_CID >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_CID      ) & 0xFF );
+    ext_len = (size_t) ssl->own_cid_len + 1;
+    *p++ = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( ext_len      ) & 0xFF );
+
+    *p++ = (uint8_t) ssl->own_cid_len;
+    memcpy( p, ssl->own_cid, ssl->own_cid_len );
+
+    *olen = ssl->own_cid_len + 5;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
+
+#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
+static int ssl_write_max_fragment_length_ext( mbedtls_ssl_context *ssl,
+                                              unsigned char *buf,
+                                              const unsigned char *end,
+                                              size_t *olen )
+{
+    unsigned char *p = buf;
+
+    *olen = 0;
+
+    if( ssl->conf->mfl_code == MBEDTLS_SSL_MAX_FRAG_LEN_NONE )
+        return( 0 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3,
+        ( "client hello, adding max_fragment_length extension" ) );
+
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 5 );
+
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH >> 8 )
+                            & 0xFF );
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH      )
+                            & 0xFF );
+
+    *p++ = 0x00;
+    *p++ = 1;
+
+    *p++ = ssl->conf->mfl_code;
+
+    *olen = 5;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
+
+#if defined(MBEDTLS_SSL_TRUNCATED_HMAC)
+static int ssl_write_truncated_hmac_ext( mbedtls_ssl_context *ssl,
+                                         unsigned char *buf,
+                                         const unsigned char *end,
+                                         size_t *olen )
+{
+    unsigned char *p = buf;
+
+    *olen = 0;
+
+    if( ssl->conf->trunc_hmac == MBEDTLS_SSL_TRUNC_HMAC_DISABLED )
+        return( 0 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3,
+        ( "client hello, adding truncated_hmac extension" ) );
+
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
+
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_TRUNCATED_HMAC >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_TRUNCATED_HMAC      ) & 0xFF );
+
+    *p++ = 0x00;
+    *p++ = 0x00;
+
+    *olen = 4;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_TRUNCATED_HMAC */
+
+#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
+static int ssl_write_encrypt_then_mac_ext( mbedtls_ssl_context *ssl,
+                                           unsigned char *buf,
+                                           const unsigned char *end,
+                                           size_t *olen )
+{
+    unsigned char *p = buf;
+
+    *olen = 0;
+
+    if( ssl->conf->encrypt_then_mac == MBEDTLS_SSL_ETM_DISABLED ||
+        ssl->conf->max_minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
+        return( 0 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3,
+        ( "client hello, adding encrypt_then_mac extension" ) );
+
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
+
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC      ) & 0xFF );
+
+    *p++ = 0x00;
+    *p++ = 0x00;
+
+    *olen = 4;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
+
+#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
+static int ssl_write_extended_ms_ext( mbedtls_ssl_context *ssl,
+                                      unsigned char *buf,
+                                      const unsigned char *end,
+                                      size_t *olen )
+{
+    unsigned char *p = buf;
+
+    *olen = 0;
+
+    if( ssl->conf->extended_ms == MBEDTLS_SSL_EXTENDED_MS_DISABLED ||
+        ssl->conf->max_minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
+        return( 0 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3,
+        ( "client hello, adding extended_master_secret extension" ) );
+
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
+
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET >> 8 )
+                            & 0xFF );
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET      )
+                            & 0xFF );
+
+    *p++ = 0x00;
+    *p++ = 0x00;
+
+    *olen = 4;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_EXTENDED_MASTER_SECRET */
+
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+static int ssl_write_session_ticket_ext( mbedtls_ssl_context *ssl,
+                                         unsigned char *buf,
+                                         const unsigned char *end,
+                                         size_t *olen )
+{
+    unsigned char *p = buf;
+    size_t tlen = ssl->session_negotiate->ticket_len;
+
+    *olen = 0;
+
+    if( ssl->conf->session_tickets == MBEDTLS_SSL_SESSION_TICKETS_DISABLED )
+        return( 0 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3,
+        ( "client hello, adding session ticket extension" ) );
+
+    /* The addition is safe here since the ticket length is 16 bit. */
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 + tlen );
+
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SESSION_TICKET >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SESSION_TICKET      ) & 0xFF );
+
+    *p++ = (unsigned char)( ( tlen >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( tlen      ) & 0xFF );
+
+    *olen = 4;
+
+    if( ssl->session_negotiate->ticket == NULL || tlen == 0 )
+        return( 0 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3,
+        ( "sending session ticket of length %" MBEDTLS_PRINTF_SIZET, tlen ) );
+
+    memcpy( p, ssl->session_negotiate->ticket, tlen );
+
+    *olen += tlen;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_SESSION_TICKETS */
+
+#if defined(MBEDTLS_SSL_ALPN)
+static int ssl_write_alpn_ext( mbedtls_ssl_context *ssl,
+                               unsigned char *buf,
+                               const unsigned char *end,
+                               size_t *olen )
+{
+    unsigned char *p = buf;
+    size_t alpnlen = 0;
+    const char **cur;
+
+    *olen = 0;
+
+    if( ssl->conf->alpn_list == NULL )
+        return( 0 );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, adding alpn extension" ) );
+
+    for( cur = ssl->conf->alpn_list; *cur != NULL; cur++ )
+        alpnlen += strlen( *cur ) + 1;
+
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 + alpnlen );
+
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ALPN >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ALPN      ) & 0xFF );
+
+    /*
+     * opaque ProtocolName<1..2^8-1>;
+     *
+     * struct {
+     *     ProtocolName protocol_name_list<2..2^16-1>
+     * } ProtocolNameList;
+     */
+
+    /* Skip writing extension and list length for now */
+    p += 4;
+
+    for( cur = ssl->conf->alpn_list; *cur != NULL; cur++ )
+    {
+        /*
+         * mbedtls_ssl_conf_set_alpn_protocols() checked that the length of
+         * protocol names is less than 255.
+         */
+        *p = (unsigned char)strlen( *cur );
+        memcpy( p + 1, *cur, *p );
+        p += 1 + *p;
+    }
+
+    *olen = p - buf;
+
+    /* List length = olen - 2 (ext_type) - 2 (ext_len) - 2 (list_len) */
+    buf[4] = (unsigned char)( ( ( *olen - 6 ) >> 8 ) & 0xFF );
+    buf[5] = (unsigned char)( ( ( *olen - 6 )      ) & 0xFF );
+
+    /* Extension length = olen - 2 (ext_type) - 2 (ext_len) */
+    buf[2] = (unsigned char)( ( ( *olen - 4 ) >> 8 ) & 0xFF );
+    buf[3] = (unsigned char)( ( ( *olen - 4 )      ) & 0xFF );
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_ALPN */
+
+#if defined(MBEDTLS_SSL_DTLS_SRTP)
+static int ssl_write_use_srtp_ext( mbedtls_ssl_context *ssl,
+                                   unsigned char *buf,
+                                   const unsigned char *end,
+                                   size_t *olen )
+{
+    unsigned char *p = buf;
+    size_t protection_profiles_index = 0, ext_len = 0;
+    uint16_t mki_len = 0, profile_value = 0;
+
+    *olen = 0;
+
+    if( ( ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM ) ||
+        ( ssl->conf->dtls_srtp_profile_list == NULL ) ||
+        ( ssl->conf->dtls_srtp_profile_list_len == 0 ) )
+    {
+        return( 0 );
+    }
+
+    /* RFC 5764 section 4.1.1
+     * uint8 SRTPProtectionProfile[2];
+     *
+     * struct {
+     *   SRTPProtectionProfiles SRTPProtectionProfiles;
+     *   opaque srtp_mki<0..255>;
+     * } UseSRTPData;
+     * SRTPProtectionProfile SRTPProtectionProfiles<2..2^16-1>;
+     */
+    if( ssl->conf->dtls_srtp_mki_support == MBEDTLS_SSL_DTLS_SRTP_MKI_SUPPORTED )
+    {
+        mki_len = ssl->dtls_srtp_info.mki_len;
+    }
+    /* Extension length = 2 bytes for profiles length,
+     *                    ssl->conf->dtls_srtp_profile_list_len * 2 (each profile is 2 bytes length ),
+     *                    1 byte for srtp_mki vector length and the mki_len value
+     */
+    ext_len = 2 + 2 * ( ssl->conf->dtls_srtp_profile_list_len ) + 1 + mki_len;
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, adding use_srtp extension" ) );
+
+    /* Check there is room in the buffer for the extension + 4 bytes
+     * - the extension tag (2 bytes)
+     * - the extension length (2 bytes)
+     */
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, ext_len + 4 );
+
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP      ) & 0xFF );
+
+
+    *p++ = (unsigned char)( ( ( ext_len & 0xFF00 ) >> 8 ) & 0xFF );
+    *p++ = (unsigned char)( ext_len & 0xFF );
+
+    /* protection profile length: 2*(ssl->conf->dtls_srtp_profile_list_len) */
+    /* micro-optimization:
+     * the list size is limited to MBEDTLS_TLS_SRTP_MAX_PROFILE_LIST_LENGTH
+     * which is lower than 127, so the upper byte of the length is always 0
+     * For the documentation, the more generic code is left in comments
+     * *p++ = (unsigned char)( ( ( 2 * ssl->conf->dtls_srtp_profile_list_len )
+     *                        >> 8 ) & 0xFF );
+     */
+    *p++ = 0;
+    *p++ = (unsigned char)( ( 2 * ssl->conf->dtls_srtp_profile_list_len )
+                            & 0xFF );
+
+    for( protection_profiles_index=0;
+         protection_profiles_index < ssl->conf->dtls_srtp_profile_list_len;
+         protection_profiles_index++ )
+    {
+        profile_value = mbedtls_ssl_check_srtp_profile_value
+                ( ssl->conf->dtls_srtp_profile_list[protection_profiles_index] );
+        if( profile_value != MBEDTLS_TLS_SRTP_UNSET )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_write_use_srtp_ext, add profile: %04x",
+                                        profile_value ) );
+            *p++ = ( ( profile_value >> 8 ) & 0xFF );
+            *p++ = ( profile_value & 0xFF );
+        }
+        else
+        {
+            /*
+             * Note: we shall never arrive here as protection profiles
+             * is checked by mbedtls_ssl_conf_dtls_srtp_protection_profiles function
+             */
+            MBEDTLS_SSL_DEBUG_MSG( 3,
+                    ( "client hello, "
+                      "illegal DTLS-SRTP protection profile %d",
+                      ssl->conf->dtls_srtp_profile_list[protection_profiles_index]
+                    ) );
+            return( MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED );
+        }
+    }
+
+    *p++ = mki_len & 0xFF;
+
+    if( mki_len != 0 )
+    {
+        memcpy( p, ssl->dtls_srtp_info.mki_value, mki_len );
+        /*
+         * Increment p to point to the current position.
+         */
+        p += mki_len;
+        MBEDTLS_SSL_DEBUG_BUF( 3, "sending mki",  ssl->dtls_srtp_info.mki_value,
+                               ssl->dtls_srtp_info.mki_len );
+    }
+
+    /*
+     * total extension length: extension type (2 bytes)
+     *                         + extension length (2 bytes)
+     *                         + protection profile length (2 bytes)
+     *                         + 2 * number of protection profiles
+     *                         + srtp_mki vector length(1 byte)
+     *                         + mki value
+     */
+    *olen = p - buf;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_DTLS_SRTP */
+
+/*
+ * Generate random bytes for ClientHello
+ */
+static int ssl_generate_random( mbedtls_ssl_context *ssl )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    unsigned char *p = ssl->handshake->randbytes;
+#if defined(MBEDTLS_HAVE_TIME)
+    mbedtls_time_t t;
+#endif
+
+    /*
+     * When responding to a verify request, MUST reuse random (RFC 6347 4.2.1)
+     */
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+        ssl->handshake->verify_cookie != NULL )
+    {
+        return( 0 );
+    }
+#endif
+
+#if defined(MBEDTLS_HAVE_TIME)
+    t = mbedtls_time( NULL );
+    *p++ = (unsigned char)( t >> 24 );
+    *p++ = (unsigned char)( t >> 16 );
+    *p++ = (unsigned char)( t >>  8 );
+    *p++ = (unsigned char)( t       );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, current time: %" MBEDTLS_PRINTF_LONGLONG,
+                                (long long) t ) );
+#else
+    if( ( ret = ssl->conf->f_rng( ssl->conf->p_rng, p, 4 ) ) != 0 )
+        return( ret );
+
+    p += 4;
+#endif /* MBEDTLS_HAVE_TIME */
+
+    if( ( ret = ssl->conf->f_rng( ssl->conf->p_rng, p, 28 ) ) != 0 )
+        return( ret );
+
+    return( 0 );
+}
+
+/**
+ * \brief           Validate cipher suite against config in SSL context.
+ *
+ * \param suite_info    cipher suite to validate
+ * \param ssl           SSL context
+ * \param min_minor_ver Minimal minor version to accept a cipher suite
+ * \param max_minor_ver Maximal minor version to accept a cipher suite
+ *
+ * \return          0 if valid, else 1
+ */
+static int ssl_validate_ciphersuite(
+    const mbedtls_ssl_ciphersuite_t * suite_info,
+    const mbedtls_ssl_context * ssl,
+    int min_minor_ver, int max_minor_ver )
+{
+    (void) ssl;
+    if( suite_info == NULL )
+        return( 1 );
+
+    if( suite_info->min_minor_ver > max_minor_ver ||
+            suite_info->max_minor_ver < min_minor_ver )
+        return( 1 );
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+            ( suite_info->flags & MBEDTLS_CIPHERSUITE_NODTLS ) )
+        return( 1 );
+#endif
+
+#if defined(MBEDTLS_ARC4_C)
+    if( ssl->conf->arc4_disabled == MBEDTLS_SSL_ARC4_DISABLED &&
+            suite_info->cipher == MBEDTLS_CIPHER_ARC4_128 )
+        return( 1 );
+#endif
+
+#if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+    if( suite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECJPAKE &&
+            mbedtls_ecjpake_check( &ssl->handshake->ecjpake_ctx ) != 0 )
+        return( 1 );
+#endif
+
+    /* Don't suggest PSK-based ciphersuite if no PSK is available. */
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+    if( mbedtls_ssl_ciphersuite_uses_psk( suite_info ) &&
+        ssl_conf_has_static_psk( ssl->conf ) == 0 )
+    {
+        return( 1 );
+    }
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
+
+    return( 0 );
+}
+
+static int ssl_write_client_hello( mbedtls_ssl_context *ssl )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    size_t i, n, olen, ext_len = 0;
+
+    unsigned char *buf;
+    unsigned char *p, *q;
+    const unsigned char *end;
+
+    unsigned char offer_compress;
+    const int *ciphersuites;
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
+#if defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C) || \
+    defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+    int uses_ec = 0;
+#endif
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write client hello" ) );
+
+    if( ssl->conf->f_rng == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "no RNG provided") );
+        return( MBEDTLS_ERR_SSL_NO_RNG );
+    }
+
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    if( ssl->renego_status == MBEDTLS_SSL_INITIAL_HANDSHAKE )
+#endif
+    {
+        ssl->major_ver = ssl->conf->min_major_ver;
+        ssl->minor_ver = ssl->conf->min_minor_ver;
+    }
+
+    if( ssl->conf->max_major_ver == 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "configured max major version is invalid, consider using mbedtls_ssl_config_defaults()" ) );
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
+    buf = ssl->out_msg;
+    end = buf + MBEDTLS_SSL_OUT_CONTENT_LEN;
+
+    /*
+     * Check if there's enough space for the first part of the ClientHello
+     * consisting of the 38 bytes described below, the session identifier (at
+     * most 32 bytes) and its length (1 byte).
+     *
+     * Use static upper bounds instead of the actual values
+     * to allow the compiler to optimize this away.
+     */
+    MBEDTLS_SSL_CHK_BUF_PTR( buf, end, 38 + 1 + 32 );
+
+    /*
+     * The 38 first bytes of the ClientHello:
+     *     0  .   0   handshake type (written later)
+     *     1  .   3   handshake length (written later)
+     *     4  .   5   highest version supported
+     *     6  .   9   current UNIX time
+     *    10  .  37   random bytes
+     *
+     * The current UNIX time (4 bytes) and following 28 random bytes are written
+     * by ssl_generate_random() into ssl->handshake->randbytes buffer and then
+     * copied from there into the output buffer.
+     */
+
+    p = buf + 4;
+    mbedtls_ssl_write_version( ssl->conf->max_major_ver,
+                               ssl->conf->max_minor_ver,
+                               ssl->conf->transport, p );
+    p += 2;
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, max version: [%d:%d]",
+                   buf[4], buf[5] ) );
+
+    if( ( ret = ssl_generate_random( ssl ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_generate_random", ret );
+        return( ret );
+    }
+
+    memcpy( p, ssl->handshake->randbytes, 32 );
+    MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, random bytes", p, 32 );
+    p += 32;
+
+    /*
+     *    38  .  38   session id length
+     *    39  . 39+n  session id
+     *   39+n . 39+n  DTLS only: cookie length (1 byte)
+     *   40+n .  ..   DTLS only: cookie
+     *   ..   . ..    ciphersuitelist length (2 bytes)
+     *   ..   . ..    ciphersuitelist
+     *   ..   . ..    compression methods length (1 byte)
+     *   ..   . ..    compression methods
+     *   ..   . ..    extensions length (2 bytes)
+     *   ..   . ..    extensions
+     */
+    n = ssl->session_negotiate->id_len;
+
+    if( n < 16 || n > 32 ||
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+        ssl->renego_status != MBEDTLS_SSL_INITIAL_HANDSHAKE ||
+#endif
+        ssl->handshake->resume == 0 )
+    {
+        n = 0;
+    }
+
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+    /*
+     * RFC 5077 section 3.4: "When presenting a ticket, the client MAY
+     * generate and include a Session ID in the TLS ClientHello."
+     */
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    if( ssl->renego_status == MBEDTLS_SSL_INITIAL_HANDSHAKE )
+#endif
+    {
+        if( ssl->session_negotiate->ticket != NULL &&
+                ssl->session_negotiate->ticket_len != 0 )
+        {
+            ret = ssl->conf->f_rng( ssl->conf->p_rng,
+                                    ssl->session_negotiate->id, 32 );
+
+            if( ret != 0 )
+                return( ret );
+
+            ssl->session_negotiate->id_len = n = 32;
+        }
+    }
+#endif /* MBEDTLS_SSL_SESSION_TICKETS */
+
+    /*
+     * The first check of the output buffer size above (
+     * MBEDTLS_SSL_CHK_BUF_PTR( buf, end, 38 + 1 + 32 );)
+     * has checked that there is enough space in the output buffer for the
+     * session identifier length byte and the session identifier (n <= 32).
+     */
+    *p++ = (unsigned char) n;
+
+    for( i = 0; i < n; i++ )
+        *p++ = ssl->session_negotiate->id[i];
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, session id len.: %" MBEDTLS_PRINTF_SIZET, n ) );
+    MBEDTLS_SSL_DEBUG_BUF( 3,   "client hello, session id", buf + 39, n );
+
+    /*
+     *   With 'n' being the length of the session identifier
+     *
+     *   39+n . 39+n  DTLS only: cookie length (1 byte)
+     *   40+n .  ..   DTLS only: cookie
+     *   ..   . ..    ciphersuitelist length (2 bytes)
+     *   ..   . ..    ciphersuitelist
+     *   ..   . ..    compression methods length (1 byte)
+     *   ..   . ..    compression methods
+     *   ..   . ..    extensions length (2 bytes)
+     *   ..   . ..    extensions
+     */
+
+    /*
+     * DTLS cookie
+     */
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        MBEDTLS_SSL_CHK_BUF_PTR( p, end, 1 );
+
+        if( ssl->handshake->verify_cookie == NULL )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "no verify cookie to send" ) );
+            *p++ = 0;
+        }
+        else
+        {
+            MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, cookie",
+                              ssl->handshake->verify_cookie,
+                              ssl->handshake->verify_cookie_len );
+
+            *p++ = ssl->handshake->verify_cookie_len;
+
+            MBEDTLS_SSL_CHK_BUF_PTR( p, end,
+                                     ssl->handshake->verify_cookie_len );
+            memcpy( p, ssl->handshake->verify_cookie,
+                       ssl->handshake->verify_cookie_len );
+            p += ssl->handshake->verify_cookie_len;
+        }
+    }
+#endif
+
+    /*
+     * Ciphersuite list
+     */
+    ciphersuites = ssl->conf->ciphersuite_list[ssl->minor_ver];
+
+    /* Skip writing ciphersuite length for now */
+    n = 0;
+    q = p;
+
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
+    p += 2;
+
+    for( i = 0; ciphersuites[i] != 0; i++ )
+    {
+        ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( ciphersuites[i] );
+
+        if( ssl_validate_ciphersuite( ciphersuite_info, ssl,
+                                      ssl->conf->min_minor_ver,
+                                      ssl->conf->max_minor_ver ) != 0 )
+            continue;
+
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, add ciphersuite: %#04x (%s)",
+                                    (unsigned int)ciphersuites[i], ciphersuite_info->name ) );
+
+#if defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C) || \
+    defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+        uses_ec |= mbedtls_ssl_ciphersuite_uses_ec( ciphersuite_info );
+#endif
+
+        MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
+
+        n++;
+        *p++ = (unsigned char)( ciphersuites[i] >> 8 );
+        *p++ = (unsigned char)( ciphersuites[i]      );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 3,
+        ( "client hello, got %" MBEDTLS_PRINTF_SIZET " ciphersuites (excluding SCSVs)", n ) );
+
+    /*
+     * Add TLS_EMPTY_RENEGOTIATION_INFO_SCSV
+     */
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    if( ssl->renego_status == MBEDTLS_SSL_INITIAL_HANDSHAKE )
+#endif
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "adding EMPTY_RENEGOTIATION_INFO_SCSV" ) );
+        MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
+        *p++ = (unsigned char)( MBEDTLS_SSL_EMPTY_RENEGOTIATION_INFO >> 8 );
+        *p++ = (unsigned char)( MBEDTLS_SSL_EMPTY_RENEGOTIATION_INFO      );
+        n++;
+    }
+
+    /* Some versions of OpenSSL don't handle it correctly if not at end */
+#if defined(MBEDTLS_SSL_FALLBACK_SCSV)
+    if( ssl->conf->fallback == MBEDTLS_SSL_IS_FALLBACK )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "adding FALLBACK_SCSV" ) );
+
+        MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
+        *p++ = (unsigned char)( MBEDTLS_SSL_FALLBACK_SCSV_VALUE >> 8 );
+        *p++ = (unsigned char)( MBEDTLS_SSL_FALLBACK_SCSV_VALUE      );
+        n++;
+    }
+#endif
+
+    *q++ = (unsigned char)( n >> 7 );
+    *q++ = (unsigned char)( n << 1 );
+
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+    offer_compress = 1;
+#else
+    offer_compress = 0;
+#endif
+
+    /*
+     * We don't support compression with DTLS right now: if many records come
+     * in the same datagram, uncompressing one could overwrite the next one.
+     * We don't want to add complexity for handling that case unless there is
+     * an actual need for it.
+     */
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+        offer_compress = 0;
+#endif
+
+    if( offer_compress )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, compress len.: %d", 2 ) );
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, compress alg.: %d %d",
+                                    MBEDTLS_SSL_COMPRESS_DEFLATE,
+                                    MBEDTLS_SSL_COMPRESS_NULL ) );
+
+        MBEDTLS_SSL_CHK_BUF_PTR( p, end, 3 );
+        *p++ = 2;
+        *p++ = MBEDTLS_SSL_COMPRESS_DEFLATE;
+        *p++ = MBEDTLS_SSL_COMPRESS_NULL;
+    }
+    else
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, compress len.: %d", 1 ) );
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, compress alg.: %d",
+                            MBEDTLS_SSL_COMPRESS_NULL ) );
+
+        MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
+        *p++ = 1;
+        *p++ = MBEDTLS_SSL_COMPRESS_NULL;
+    }
+
+    /* First write extensions, then the total length */
+
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
+
+#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
+    if( ( ret = ssl_write_hostname_ext( ssl, p + 2 + ext_len,
+                                        end, &olen ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_hostname_ext", ret );
+        return( ret );
+    }
+    ext_len += olen;
+#endif
+
+    /* Note that TLS_EMPTY_RENEGOTIATION_INFO_SCSV is always added
+     * even if MBEDTLS_SSL_RENEGOTIATION is not defined. */
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    if( ( ret = ssl_write_renegotiation_ext( ssl, p + 2 + ext_len,
+                                             end, &olen ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_renegotiation_ext", ret );
+        return( ret );
+    }
+    ext_len += olen;
+#endif
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
+    defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
+    if( ( ret = ssl_write_signature_algorithms_ext( ssl, p + 2 + ext_len,
+                                                    end, &olen ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_signature_algorithms_ext", ret );
+        return( ret );
+    }
+    ext_len += olen;
+#endif
+
+#if defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C) || \
+    defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+    if( uses_ec )
+    {
+        if( ( ret = ssl_write_supported_elliptic_curves_ext( ssl, p + 2 + ext_len,
+                                                             end, &olen ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_supported_elliptic_curves_ext", ret );
+            return( ret );
+        }
+        ext_len += olen;
+
+        if( ( ret = ssl_write_supported_point_formats_ext( ssl, p + 2 + ext_len,
+                                                           end, &olen ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_supported_point_formats_ext", ret );
+            return( ret );
+        }
+        ext_len += olen;
+    }
+#endif
+
+#if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+    if( ( ret = ssl_write_ecjpake_kkpp_ext( ssl, p + 2 + ext_len,
+                                            end, &olen ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_ecjpake_kkpp_ext", ret );
+        return( ret );
+    }
+    ext_len += olen;
+#endif
+
+#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
+    if( ( ret = ssl_write_cid_ext( ssl, p + 2 + ext_len, end, &olen ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_cid_ext", ret );
+        return( ret );
+    }
+    ext_len += olen;
+#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
+
+#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
+    if( ( ret = ssl_write_max_fragment_length_ext( ssl, p + 2 + ext_len,
+                                                   end, &olen ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_max_fragment_length_ext", ret );
+        return( ret );
+    }
+    ext_len += olen;
+#endif
+
+#if defined(MBEDTLS_SSL_TRUNCATED_HMAC)
+    if( ( ret = ssl_write_truncated_hmac_ext( ssl, p + 2 + ext_len,
+                                              end, &olen ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_truncated_hmac_ext", ret );
+        return( ret );
+    }
+    ext_len += olen;
+#endif
+
+#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
+    if( ( ret = ssl_write_encrypt_then_mac_ext( ssl, p + 2 + ext_len,
+                                                end, &olen ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_encrypt_then_mac_ext", ret );
+        return( ret );
+    }
+    ext_len += olen;
+#endif
+
+#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
+    if( ( ret = ssl_write_extended_ms_ext( ssl, p + 2 + ext_len,
+                                           end, &olen ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_extended_ms_ext", ret );
+        return( ret );
+    }
+    ext_len += olen;
+#endif
+
+#if defined(MBEDTLS_SSL_ALPN)
+    if( ( ret = ssl_write_alpn_ext( ssl, p + 2 + ext_len,
+                                    end, &olen ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_alpn_ext", ret );
+        return( ret );
+    }
+    ext_len += olen;
+#endif
+
+#if defined(MBEDTLS_SSL_DTLS_SRTP)
+    if( ( ret = ssl_write_use_srtp_ext( ssl, p + 2 + ext_len,
+                                        end, &olen ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_use_srtp_ext", ret );
+        return( ret );
+    }
+    ext_len += olen;
+#endif
+
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+    if( ( ret = ssl_write_session_ticket_ext( ssl, p + 2 + ext_len,
+                                              end, &olen ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_session_ticket_ext", ret );
+        return( ret );
+    }
+    ext_len += olen;
+#endif
+
+    /* olen unused if all extensions are disabled */
+    ((void) olen);
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, total extension length: %" MBEDTLS_PRINTF_SIZET,
+                                ext_len ) );
+
+    if( ext_len > 0 )
+    {
+        /* No need to check for space here, because the extension
+         * writing functions already took care of that. */
+        *p++ = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
+        *p++ = (unsigned char)( ( ext_len      ) & 0xFF );
+        p += ext_len;
+    }
+
+    ssl->out_msglen  = p - buf;
+    ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
+    ssl->out_msg[0]  = MBEDTLS_SSL_HS_CLIENT_HELLO;
+
+    ssl->state++;
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+        mbedtls_ssl_send_flight_completed( ssl );
+#endif
+
+    if( ( ret = mbedtls_ssl_write_handshake_msg( ssl ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_handshake_msg", ret );
+        return( ret );
+    }
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+        ( ret = mbedtls_ssl_flight_transmit( ssl ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_flight_transmit", ret );
+        return( ret );
+    }
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write client hello" ) );
+
+    return( 0 );
+}
+
+static int ssl_parse_renegotiation_info( mbedtls_ssl_context *ssl,
+                                         const unsigned char *buf,
+                                         size_t len )
+{
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    if( ssl->renego_status != MBEDTLS_SSL_INITIAL_HANDSHAKE )
+    {
+        /* Check verify-data in constant-time. The length OTOH is no secret */
+        if( len    != 1 + ssl->verify_data_len * 2 ||
+            buf[0] !=     ssl->verify_data_len * 2 ||
+            mbedtls_ssl_safer_memcmp( buf + 1,
+                          ssl->own_verify_data, ssl->verify_data_len ) != 0 ||
+            mbedtls_ssl_safer_memcmp( buf + 1 + ssl->verify_data_len,
+                          ssl->peer_verify_data, ssl->verify_data_len ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "non-matching renegotiation info" ) );
+            mbedtls_ssl_send_alert_message(
+                ssl,
+                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE );
+            return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+        }
+    }
+    else
+#endif /* MBEDTLS_SSL_RENEGOTIATION */
+    {
+        if( len != 1 || buf[0] != 0x00 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1,
+                ( "non-zero length renegotiation info" ) );
+            mbedtls_ssl_send_alert_message(
+                ssl,
+                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE );
+            return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+        }
+
+        ssl->secure_renegotiation = MBEDTLS_SSL_SECURE_RENEGOTIATION;
+    }
+
+    return( 0 );
+}
+
+#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
+static int ssl_parse_max_fragment_length_ext( mbedtls_ssl_context *ssl,
+                                              const unsigned char *buf,
+                                              size_t len )
+{
+    /*
+     * server should use the extension only if we did,
+     * and if so the server's value should match ours (and len is always 1)
+     */
+    if( ssl->conf->mfl_code == MBEDTLS_SSL_MAX_FRAG_LEN_NONE ||
+        len != 1 ||
+        buf[0] != ssl->conf->mfl_code )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "non-matching max fragment length extension" ) );
+        mbedtls_ssl_send_alert_message(
+            ssl,
+            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+            MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
+
+#if defined(MBEDTLS_SSL_TRUNCATED_HMAC)
+static int ssl_parse_truncated_hmac_ext( mbedtls_ssl_context *ssl,
+                                         const unsigned char *buf,
+                                         size_t len )
+{
+    if( ssl->conf->trunc_hmac == MBEDTLS_SSL_TRUNC_HMAC_DISABLED ||
+        len != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "non-matching truncated HMAC extension" ) );
+        mbedtls_ssl_send_alert_message(
+            ssl,
+            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+            MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    ((void) buf);
+
+    ssl->session_negotiate->trunc_hmac = MBEDTLS_SSL_TRUNC_HMAC_ENABLED;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_TRUNCATED_HMAC */
+
+#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
+static int ssl_parse_cid_ext( mbedtls_ssl_context *ssl,
+                              const unsigned char *buf,
+                              size_t len )
+{
+    size_t peer_cid_len;
+
+    if( /* CID extension only makes sense in DTLS */
+        ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM ||
+        /* The server must only send the CID extension if we have offered it. */
+        ssl->negotiate_cid == MBEDTLS_SSL_CID_DISABLED )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "CID extension unexpected" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                     MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    if( len == 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "CID extension invalid" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                     MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    peer_cid_len = *buf++;
+    len--;
+
+    if( peer_cid_len > MBEDTLS_SSL_CID_OUT_LEN_MAX )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "CID extension invalid" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                     MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    if( len != peer_cid_len )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "CID extension invalid" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                     MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    ssl->handshake->cid_in_use = MBEDTLS_SSL_CID_ENABLED;
+    ssl->handshake->peer_cid_len = (uint8_t) peer_cid_len;
+    memcpy( ssl->handshake->peer_cid, buf, peer_cid_len );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "Use of CID extension negotiated" ) );
+    MBEDTLS_SSL_DEBUG_BUF( 3, "Server CID", buf, peer_cid_len );
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
+
+#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
+static int ssl_parse_encrypt_then_mac_ext( mbedtls_ssl_context *ssl,
+                                         const unsigned char *buf,
+                                         size_t len )
+{
+    if( ssl->conf->encrypt_then_mac == MBEDTLS_SSL_ETM_DISABLED ||
+        ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 ||
+        len != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "non-matching encrypt-then-MAC extension" ) );
+        mbedtls_ssl_send_alert_message(
+            ssl,
+            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+            MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    ((void) buf);
+
+    ssl->session_negotiate->encrypt_then_mac = MBEDTLS_SSL_ETM_ENABLED;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
+
+#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
+static int ssl_parse_extended_ms_ext( mbedtls_ssl_context *ssl,
+                                         const unsigned char *buf,
+                                         size_t len )
+{
+    if( ssl->conf->extended_ms == MBEDTLS_SSL_EXTENDED_MS_DISABLED ||
+        ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 ||
+        len != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "non-matching extended master secret extension" ) );
+        mbedtls_ssl_send_alert_message(
+            ssl,
+            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+            MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    ((void) buf);
+
+    ssl->handshake->extended_ms = MBEDTLS_SSL_EXTENDED_MS_ENABLED;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_EXTENDED_MASTER_SECRET */
+
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+static int ssl_parse_session_ticket_ext( mbedtls_ssl_context *ssl,
+                                         const unsigned char *buf,
+                                         size_t len )
+{
+    if( ssl->conf->session_tickets == MBEDTLS_SSL_SESSION_TICKETS_DISABLED ||
+        len != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "non-matching session ticket extension" ) );
+        mbedtls_ssl_send_alert_message(
+            ssl,
+            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+            MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    ((void) buf);
+
+    ssl->handshake->new_session_ticket = 1;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_SESSION_TICKETS */
+
+#if defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C) || \
+    defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+static int ssl_parse_supported_point_formats_ext( mbedtls_ssl_context *ssl,
+                                                  const unsigned char *buf,
+                                                  size_t len )
+{
+    size_t list_size;
+    const unsigned char *p;
+
+    if( len == 0 || (size_t)( buf[0] + 1 ) != len )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+    list_size = buf[0];
+
+    p = buf + 1;
+    while( list_size > 0 )
+    {
+        if( p[0] == MBEDTLS_ECP_PF_UNCOMPRESSED ||
+            p[0] == MBEDTLS_ECP_PF_COMPRESSED )
+        {
+#if defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C)
+            ssl->handshake->ecdh_ctx.point_format = p[0];
+#endif
+#if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+            ssl->handshake->ecjpake_ctx.point_format = p[0];
+#endif
+            MBEDTLS_SSL_DEBUG_MSG( 4, ( "point format selected: %d", p[0] ) );
+            return( 0 );
+        }
+
+        list_size--;
+        p++;
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 1, ( "no point format in common" ) );
+    mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                    MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE );
+    return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+}
+#endif /* MBEDTLS_ECDH_C || MBEDTLS_ECDSA_C ||
+          MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */
+
+#if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+static int ssl_parse_ecjpake_kkpp( mbedtls_ssl_context *ssl,
+                                   const unsigned char *buf,
+                                   size_t len )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    if( ssl->handshake->ciphersuite_info->key_exchange !=
+        MBEDTLS_KEY_EXCHANGE_ECJPAKE )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "skip ecjpake kkpp extension" ) );
+        return( 0 );
+    }
+
+    /* If we got here, we no longer need our cached extension */
+    mbedtls_free( ssl->handshake->ecjpake_cache );
+    ssl->handshake->ecjpake_cache = NULL;
+    ssl->handshake->ecjpake_cache_len = 0;
+
+    if( ( ret = mbedtls_ecjpake_read_round_one( &ssl->handshake->ecjpake_ctx,
+                                                buf, len ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecjpake_read_round_one", ret );
+        mbedtls_ssl_send_alert_message(
+            ssl,
+            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+            MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE );
+        return( ret );
+    }
+
+    return( 0 );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */
+
+#if defined(MBEDTLS_SSL_ALPN)
+static int ssl_parse_alpn_ext( mbedtls_ssl_context *ssl,
+                               const unsigned char *buf, size_t len )
+{
+    size_t list_len, name_len;
+    const char **p;
+
+    /* If we didn't send it, the server shouldn't send it */
+    if( ssl->conf->alpn_list == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "non-matching ALPN extension" ) );
+        mbedtls_ssl_send_alert_message(
+            ssl,
+            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+            MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    /*
+     * opaque ProtocolName<1..2^8-1>;
+     *
+     * struct {
+     *     ProtocolName protocol_name_list<2..2^16-1>
+     * } ProtocolNameList;
+     *
+     * the "ProtocolNameList" MUST contain exactly one "ProtocolName"
+     */
+
+    /* Min length is 2 (list_len) + 1 (name_len) + 1 (name) */
+    if( len < 4 )
+    {
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    list_len = ( buf[0] << 8 ) | buf[1];
+    if( list_len != len - 2 )
+    {
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    name_len = buf[2];
+    if( name_len != list_len - 1 )
+    {
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    /* Check that the server chosen protocol was in our list and save it */
+    for( p = ssl->conf->alpn_list; *p != NULL; p++ )
+    {
+        if( name_len == strlen( *p ) &&
+            memcmp( buf + 3, *p, name_len ) == 0 )
+        {
+            ssl->alpn_chosen = *p;
+            return( 0 );
+        }
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 1, ( "ALPN extension: no matching protocol" ) );
+    mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                    MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE );
+    return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+}
+#endif /* MBEDTLS_SSL_ALPN */
+
+#if defined(MBEDTLS_SSL_DTLS_SRTP)
+static int ssl_parse_use_srtp_ext( mbedtls_ssl_context *ssl,
+                                   const unsigned char *buf,
+                                   size_t len )
+{
+    mbedtls_ssl_srtp_profile server_protection = MBEDTLS_TLS_SRTP_UNSET;
+    size_t i, mki_len = 0;
+    uint16_t server_protection_profile_value = 0;
+
+    /* If use_srtp is not configured, just ignore the extension */
+    if( ( ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM ) ||
+        ( ssl->conf->dtls_srtp_profile_list == NULL ) ||
+        ( ssl->conf->dtls_srtp_profile_list_len == 0 ) )
+        return( 0 );
+
+    /* RFC 5764 section 4.1.1
+     * uint8 SRTPProtectionProfile[2];
+     *
+     * struct {
+     *   SRTPProtectionProfiles SRTPProtectionProfiles;
+     *   opaque srtp_mki<0..255>;
+     * } UseSRTPData;
+
+     * SRTPProtectionProfile SRTPProtectionProfiles<2..2^16-1>;
+     *
+     */
+    if( ssl->conf->dtls_srtp_mki_support == MBEDTLS_SSL_DTLS_SRTP_MKI_SUPPORTED )
+    {
+        mki_len = ssl->dtls_srtp_info.mki_len;
+    }
+
+    /*
+     * Length is 5 + optional mki_value : one protection profile length (2 bytes)
+     *                                      + protection profile (2 bytes)
+     *                                      + mki_len(1 byte)
+     *                                      and optional srtp_mki
+     */
+    if( ( len < 5 ) || ( len != ( buf[4] + 5u ) ) )
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+
+    /*
+     * get the server protection profile
+     */
+
+    /*
+     * protection profile length must be 0x0002 as we must have only
+     * one protection profile in server Hello
+     */
+    if( (  buf[0] != 0 ) || ( buf[1] != 2 ) )
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+
+    server_protection_profile_value = ( buf[2] << 8 ) | buf[3];
+    server_protection = mbedtls_ssl_check_srtp_profile_value(
+                    server_protection_profile_value );
+    if( server_protection != MBEDTLS_TLS_SRTP_UNSET )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "found srtp profile: %s",
+                                      mbedtls_ssl_get_srtp_profile_as_string(
+                                              server_protection ) ) );
+    }
+
+    ssl->dtls_srtp_info.chosen_dtls_srtp_profile = MBEDTLS_TLS_SRTP_UNSET;
+
+    /*
+     * Check we have the server profile in our list
+     */
+    for( i=0; i < ssl->conf->dtls_srtp_profile_list_len; i++)
+    {
+        if( server_protection == ssl->conf->dtls_srtp_profile_list[i] )
+        {
+            ssl->dtls_srtp_info.chosen_dtls_srtp_profile = ssl->conf->dtls_srtp_profile_list[i];
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "selected srtp profile: %s",
+                                      mbedtls_ssl_get_srtp_profile_as_string(
+                                              server_protection ) ) );
+            break;
+        }
+    }
+
+    /* If no match was found : server problem, it shall never answer with incompatible profile */
+    if( ssl->dtls_srtp_info.chosen_dtls_srtp_profile == MBEDTLS_TLS_SRTP_UNSET )
+    {
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    /* If server does not use mki in its reply, make sure the client won't keep
+     * one as negotiated */
+    if( len == 5 )
+    {
+        ssl->dtls_srtp_info.mki_len = 0;
+    }
+
+    /*
+     * RFC5764:
+     *  If the client detects a nonzero-length MKI in the server's response
+     *  that is different than the one the client offered, then the client
+     *  MUST abort the handshake and SHOULD send an invalid_parameter alert.
+     */
+    if( len > 5  && ( buf[4] != mki_len ||
+        ( memcmp( ssl->dtls_srtp_info.mki_value, &buf[5], mki_len ) ) ) )
+    {
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+#if defined (MBEDTLS_DEBUG_C)
+    if( len > 5 )
+    {
+        MBEDTLS_SSL_DEBUG_BUF( 3, "received mki", ssl->dtls_srtp_info.mki_value,
+                                                  ssl->dtls_srtp_info.mki_len );
+    }
+#endif
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_DTLS_SRTP */
+
+/*
+ * Parse HelloVerifyRequest.  Only called after verifying the HS type.
+ */
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+static int ssl_parse_hello_verify_request( mbedtls_ssl_context *ssl )
+{
+    const unsigned char *p = ssl->in_msg + mbedtls_ssl_hs_hdr_len( ssl );
+    int major_ver, minor_ver;
+    unsigned char cookie_len;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse hello verify request" ) );
+
+    /* Check that there is enough room for:
+     * - 2 bytes of version
+     * - 1 byte of cookie_len
+     */
+    if( mbedtls_ssl_hs_hdr_len( ssl ) + 3 > ssl->in_msglen )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "incoming HelloVerifyRequest message is too short" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                    MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    /*
+     * struct {
+     *   ProtocolVersion server_version;
+     *   opaque cookie<0..2^8-1>;
+     * } HelloVerifyRequest;
+     */
+    MBEDTLS_SSL_DEBUG_BUF( 3, "server version", p, 2 );
+    mbedtls_ssl_read_version( &major_ver, &minor_ver, ssl->conf->transport, p );
+    p += 2;
+
+    /*
+     * Since the RFC is not clear on this point, accept DTLS 1.0 (TLS 1.1)
+     * even is lower than our min version.
+     */
+    if( major_ver < MBEDTLS_SSL_MAJOR_VERSION_3 ||
+        minor_ver < MBEDTLS_SSL_MINOR_VERSION_2 ||
+        major_ver > ssl->conf->max_major_ver  ||
+        minor_ver > ssl->conf->max_minor_ver  )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server version" ) );
+
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                     MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION );
+
+        return( MBEDTLS_ERR_SSL_BAD_HS_PROTOCOL_VERSION );
+    }
+
+    cookie_len = *p++;
+    if( ( ssl->in_msg + ssl->in_msglen ) - p < cookie_len )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "cookie length does not match incoming message size" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                    MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+    MBEDTLS_SSL_DEBUG_BUF( 3, "cookie", p, cookie_len );
+
+    mbedtls_free( ssl->handshake->verify_cookie );
+
+    ssl->handshake->verify_cookie = mbedtls_calloc( 1, cookie_len );
+    if( ssl->handshake->verify_cookie  == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc failed (%d bytes)", cookie_len ) );
+        return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+    }
+
+    memcpy( ssl->handshake->verify_cookie, p, cookie_len );
+    ssl->handshake->verify_cookie_len = cookie_len;
+
+    /* Start over at ClientHello */
+    ssl->state = MBEDTLS_SSL_CLIENT_HELLO;
+    mbedtls_ssl_reset_checksum( ssl );
+
+    mbedtls_ssl_recv_flight_completed( ssl );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse hello verify request" ) );
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+static int ssl_parse_server_hello( mbedtls_ssl_context *ssl )
+{
+    int ret, i;
+    size_t n;
+    size_t ext_len;
+    unsigned char *buf, *ext;
+    unsigned char comp;
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+    int accept_comp;
+#endif
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    int renegotiation_info_seen = 0;
+#endif
+    int handshake_failure = 0;
+    const mbedtls_ssl_ciphersuite_t *suite_info;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse server hello" ) );
+
+    if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
+    {
+        /* No alert on a read error. */
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
+        return( ret );
+    }
+
+    buf = ssl->in_msg;
+
+    if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE )
+    {
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+        if( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS )
+        {
+            ssl->renego_records_seen++;
+
+            if( ssl->conf->renego_max_records >= 0 &&
+                ssl->renego_records_seen > ssl->conf->renego_max_records )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1,
+                    ( "renegotiation requested, but not honored by server" ) );
+                return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+            }
+
+            MBEDTLS_SSL_DEBUG_MSG( 1,
+                ( "non-handshake message during renegotiation" ) );
+
+            ssl->keep_current_message = 1;
+            return( MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO );
+        }
+#endif /* MBEDTLS_SSL_RENEGOTIATION */
+
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello message" ) );
+        mbedtls_ssl_send_alert_message(
+            ssl,
+            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+            MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
+        return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+    }
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
+        if( buf[0] == MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "received hello verify request" ) );
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse server hello" ) );
+            return( ssl_parse_hello_verify_request( ssl ) );
+        }
+        else
+        {
+            /* We made it through the verification process */
+            mbedtls_free( ssl->handshake->verify_cookie );
+            ssl->handshake->verify_cookie = NULL;
+            ssl->handshake->verify_cookie_len = 0;
+        }
+    }
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+    if( ssl->in_hslen < 38 + mbedtls_ssl_hs_hdr_len( ssl ) ||
+        buf[0] != MBEDTLS_SSL_HS_SERVER_HELLO )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    /*
+     *  0   .  1    server_version
+     *  2   . 33    random (maybe including 4 bytes of Unix time)
+     * 34   . 34    session_id length = n
+     * 35   . 34+n  session_id
+     * 35+n . 36+n  cipher_suite
+     * 37+n . 37+n  compression_method
+     *
+     * 38+n . 39+n  extensions length (optional)
+     * 40+n .  ..   extensions
+     */
+    buf += mbedtls_ssl_hs_hdr_len( ssl );
+
+    MBEDTLS_SSL_DEBUG_BUF( 3, "server hello, version", buf + 0, 2 );
+    mbedtls_ssl_read_version( &ssl->major_ver, &ssl->minor_ver,
+                      ssl->conf->transport, buf + 0 );
+
+    if( ssl->major_ver < ssl->conf->min_major_ver ||
+        ssl->minor_ver < ssl->conf->min_minor_ver ||
+        ssl->major_ver > ssl->conf->max_major_ver ||
+        ssl->minor_ver > ssl->conf->max_minor_ver )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "server version out of bounds -  min: [%d:%d], server: [%d:%d], max: [%d:%d]",
+              ssl->conf->min_major_ver,
+              ssl->conf->min_minor_ver,
+              ssl->major_ver, ssl->minor_ver,
+              ssl->conf->max_major_ver,
+              ssl->conf->max_minor_ver ) );
+
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                     MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION );
+
+        return( MBEDTLS_ERR_SSL_BAD_HS_PROTOCOL_VERSION );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, current time: %lu",
+                                     ( (unsigned long) buf[2] << 24 ) |
+                                     ( (unsigned long) buf[3] << 16 ) |
+                                     ( (unsigned long) buf[4] <<  8 ) |
+                                     ( (unsigned long) buf[5]       ) ) );
+
+    memcpy( ssl->handshake->randbytes + 32, buf + 2, 32 );
+
+    n = buf[34];
+
+    MBEDTLS_SSL_DEBUG_BUF( 3,   "server hello, random bytes", buf + 2, 32 );
+
+    if( n > 32 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    if( ssl->in_hslen > mbedtls_ssl_hs_hdr_len( ssl ) + 39 + n )
+    {
+        ext_len = ( ( buf[38 + n] <<  8 )
+                  | ( buf[39 + n]       ) );
+
+        if( ( ext_len > 0 && ext_len < 4 ) ||
+            ssl->in_hslen != mbedtls_ssl_hs_hdr_len( ssl ) + 40 + n + ext_len )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello message" ) );
+            mbedtls_ssl_send_alert_message(
+                ssl,
+                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+            return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+        }
+    }
+    else if( ssl->in_hslen == mbedtls_ssl_hs_hdr_len( ssl ) + 38 + n )
+    {
+        ext_len = 0;
+    }
+    else
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    /* ciphersuite (used later) */
+    i = ( buf[35 + n] << 8 ) | buf[36 + n];
+
+    /*
+     * Read and check compression
+     */
+    comp = buf[37 + n];
+
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+    /* See comments in ssl_write_client_hello() */
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+        accept_comp = 0;
+    else
+#endif
+        accept_comp = 1;
+
+    if( comp != MBEDTLS_SSL_COMPRESS_NULL &&
+        ( comp != MBEDTLS_SSL_COMPRESS_DEFLATE || accept_comp == 0 ) )
+#else /* MBEDTLS_ZLIB_SUPPORT */
+    if( comp != MBEDTLS_SSL_COMPRESS_NULL )
+#endif/* MBEDTLS_ZLIB_SUPPORT */
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "server hello, bad compression: %d", comp ) );
+        mbedtls_ssl_send_alert_message(
+            ssl,
+            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+            MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
+        return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+    }
+
+    /*
+     * Initialize update checksum functions
+     */
+    ssl->handshake->ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( i );
+    if( ssl->handshake->ciphersuite_info == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "ciphersuite info for %04x not found", (unsigned int)i ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
+    mbedtls_ssl_optimize_checksum( ssl, ssl->handshake->ciphersuite_info );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, session id len.: %" MBEDTLS_PRINTF_SIZET, n ) );
+    MBEDTLS_SSL_DEBUG_BUF( 3,   "server hello, session id", buf + 35, n );
+
+    /*
+     * Check if the session can be resumed
+     */
+    if( ssl->handshake->resume == 0 || n == 0 ||
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+        ssl->renego_status != MBEDTLS_SSL_INITIAL_HANDSHAKE ||
+#endif
+        ssl->session_negotiate->ciphersuite != i ||
+        ssl->session_negotiate->compression != comp ||
+        ssl->session_negotiate->id_len != n ||
+        memcmp( ssl->session_negotiate->id, buf + 35, n ) != 0 )
+    {
+        ssl->state++;
+        ssl->handshake->resume = 0;
+#if defined(MBEDTLS_HAVE_TIME)
+        ssl->session_negotiate->start = mbedtls_time( NULL );
+#endif
+        ssl->session_negotiate->ciphersuite = i;
+        ssl->session_negotiate->compression = comp;
+        ssl->session_negotiate->id_len = n;
+        memcpy( ssl->session_negotiate->id, buf + 35, n );
+    }
+    else
+    {
+        ssl->state = MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC;
+
+        if( ( ret = mbedtls_ssl_derive_keys( ssl ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_derive_keys", ret );
+            mbedtls_ssl_send_alert_message(
+                ssl,
+                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR );
+            return( ret );
+        }
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "%s session has been resumed",
+                   ssl->handshake->resume ? "a" : "no" ) );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, chosen ciphersuite: %04x", (unsigned) i ) );
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, compress alg.: %d",
+                                buf[37 + n] ) );
+
+    /*
+     * Perform cipher suite validation in same way as in ssl_write_client_hello.
+     */
+    i = 0;
+    while( 1 )
+    {
+        if( ssl->conf->ciphersuite_list[ssl->minor_ver][i] == 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello message" ) );
+            mbedtls_ssl_send_alert_message(
+                ssl,
+                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
+            return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+        }
+
+        if( ssl->conf->ciphersuite_list[ssl->minor_ver][i++] ==
+            ssl->session_negotiate->ciphersuite )
+        {
+            break;
+        }
+    }
+
+    suite_info = mbedtls_ssl_ciphersuite_from_id(
+        ssl->session_negotiate->ciphersuite );
+    if( ssl_validate_ciphersuite( suite_info, ssl, ssl->minor_ver,
+                                  ssl->minor_ver ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello message" ) );
+        mbedtls_ssl_send_alert_message(
+            ssl,
+            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+            MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 3,
+        ( "server hello, chosen ciphersuite: %s", suite_info->name ) );
+
+#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
+    if( suite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA &&
+        ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
+    {
+        ssl->handshake->ecrs_enabled = 1;
+    }
+#endif
+
+    if( comp != MBEDTLS_SSL_COMPRESS_NULL
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+        && comp != MBEDTLS_SSL_COMPRESS_DEFLATE
+#endif
+      )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello message" ) );
+        mbedtls_ssl_send_alert_message(
+            ssl,
+            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+            MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+    ssl->session_negotiate->compression = comp;
+
+    ext = buf + 40 + n;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2,
+        ( "server hello, total extension length: %" MBEDTLS_PRINTF_SIZET, ext_len ) );
+
+    while( ext_len )
+    {
+        unsigned int ext_id   = ( ( ext[0] <<  8 )
+                                | ( ext[1]       ) );
+        unsigned int ext_size = ( ( ext[2] <<  8 )
+                                | ( ext[3]       ) );
+
+        if( ext_size + 4 > ext_len )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello message" ) );
+            mbedtls_ssl_send_alert_message(
+                ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+            return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+        }
+
+        switch( ext_id )
+        {
+        case MBEDTLS_TLS_EXT_RENEGOTIATION_INFO:
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "found renegotiation extension" ) );
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+            renegotiation_info_seen = 1;
+#endif
+
+            if( ( ret = ssl_parse_renegotiation_info( ssl, ext + 4,
+                                                      ext_size ) ) != 0 )
+                return( ret );
+
+            break;
+
+#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
+        case MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH:
+            MBEDTLS_SSL_DEBUG_MSG( 3,
+                ( "found max_fragment_length extension" ) );
+
+            if( ( ret = ssl_parse_max_fragment_length_ext( ssl,
+                            ext + 4, ext_size ) ) != 0 )
+            {
+                return( ret );
+            }
+
+            break;
+#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
+
+#if defined(MBEDTLS_SSL_TRUNCATED_HMAC)
+        case MBEDTLS_TLS_EXT_TRUNCATED_HMAC:
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "found truncated_hmac extension" ) );
+
+            if( ( ret = ssl_parse_truncated_hmac_ext( ssl,
+                            ext + 4, ext_size ) ) != 0 )
+            {
+                return( ret );
+            }
+
+            break;
+#endif /* MBEDTLS_SSL_TRUNCATED_HMAC */
+
+#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
+        case MBEDTLS_TLS_EXT_CID:
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "found CID extension" ) );
+
+            if( ( ret = ssl_parse_cid_ext( ssl,
+                                           ext + 4,
+                                           ext_size ) ) != 0 )
+            {
+                return( ret );
+            }
+
+            break;
+#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
+
+#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
+        case MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC:
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "found encrypt_then_mac extension" ) );
+
+            if( ( ret = ssl_parse_encrypt_then_mac_ext( ssl,
+                            ext + 4, ext_size ) ) != 0 )
+            {
+                return( ret );
+            }
+
+            break;
+#endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
+
+#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
+        case MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET:
+            MBEDTLS_SSL_DEBUG_MSG( 3,
+                ( "found extended_master_secret extension" ) );
+
+            if( ( ret = ssl_parse_extended_ms_ext( ssl,
+                            ext + 4, ext_size ) ) != 0 )
+            {
+                return( ret );
+            }
+
+            break;
+#endif /* MBEDTLS_SSL_EXTENDED_MASTER_SECRET */
+
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+        case MBEDTLS_TLS_EXT_SESSION_TICKET:
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "found session_ticket extension" ) );
+
+            if( ( ret = ssl_parse_session_ticket_ext( ssl,
+                            ext + 4, ext_size ) ) != 0 )
+            {
+                return( ret );
+            }
+
+            break;
+#endif /* MBEDTLS_SSL_SESSION_TICKETS */
+
+#if defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C) || \
+    defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+        case MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS:
+            MBEDTLS_SSL_DEBUG_MSG( 3,
+                ( "found supported_point_formats extension" ) );
+
+            if( ( ret = ssl_parse_supported_point_formats_ext( ssl,
+                            ext + 4, ext_size ) ) != 0 )
+            {
+                return( ret );
+            }
+
+            break;
+#endif /* MBEDTLS_ECDH_C || MBEDTLS_ECDSA_C ||
+          MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */
+
+#if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+        case MBEDTLS_TLS_EXT_ECJPAKE_KKPP:
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "found ecjpake_kkpp extension" ) );
+
+            if( ( ret = ssl_parse_ecjpake_kkpp( ssl,
+                            ext + 4, ext_size ) ) != 0 )
+            {
+                return( ret );
+            }
+
+            break;
+#endif /* MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */
+
+#if defined(MBEDTLS_SSL_ALPN)
+        case MBEDTLS_TLS_EXT_ALPN:
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "found alpn extension" ) );
+
+            if( ( ret = ssl_parse_alpn_ext( ssl, ext + 4, ext_size ) ) != 0 )
+                return( ret );
+
+            break;
+#endif /* MBEDTLS_SSL_ALPN */
+
+#if defined(MBEDTLS_SSL_DTLS_SRTP)
+        case MBEDTLS_TLS_EXT_USE_SRTP:
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "found use_srtp extension" ) );
+
+            if( ( ret = ssl_parse_use_srtp_ext( ssl, ext + 4, ext_size ) ) != 0 )
+                return( ret );
+
+            break;
+#endif /* MBEDTLS_SSL_DTLS_SRTP */
+
+        default:
+            MBEDTLS_SSL_DEBUG_MSG( 3,
+                ( "unknown extension found: %u (ignoring)", ext_id ) );
+        }
+
+        ext_len -= 4 + ext_size;
+        ext += 4 + ext_size;
+
+        if( ext_len > 0 && ext_len < 4 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello message" ) );
+            return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+        }
+    }
+
+    /*
+     * Renegotiation security checks
+     */
+    if( ssl->secure_renegotiation == MBEDTLS_SSL_LEGACY_RENEGOTIATION &&
+        ssl->conf->allow_legacy_renegotiation ==
+        MBEDTLS_SSL_LEGACY_BREAK_HANDSHAKE )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "legacy renegotiation, breaking off handshake" ) );
+        handshake_failure = 1;
+    }
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    else if( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS &&
+             ssl->secure_renegotiation == MBEDTLS_SSL_SECURE_RENEGOTIATION &&
+             renegotiation_info_seen == 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "renegotiation_info extension missing (secure)" ) );
+        handshake_failure = 1;
+    }
+    else if( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS &&
+             ssl->secure_renegotiation == MBEDTLS_SSL_LEGACY_RENEGOTIATION &&
+             ssl->conf->allow_legacy_renegotiation ==
+             MBEDTLS_SSL_LEGACY_NO_RENEGOTIATION )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "legacy renegotiation not allowed" ) );
+        handshake_failure = 1;
+    }
+    else if( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS &&
+             ssl->secure_renegotiation == MBEDTLS_SSL_LEGACY_RENEGOTIATION &&
+             renegotiation_info_seen == 1 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "renegotiation_info extension present (legacy)" ) );
+        handshake_failure = 1;
+    }
+#endif /* MBEDTLS_SSL_RENEGOTIATION */
+
+    if( handshake_failure == 1 )
+    {
+        mbedtls_ssl_send_alert_message(
+            ssl,
+            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+            MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse server hello" ) );
+
+    return( 0 );
+}
+
+#if defined(MBEDTLS_KEY_EXCHANGE_DHE_RSA_ENABLED) ||                       \
+    defined(MBEDTLS_KEY_EXCHANGE_DHE_PSK_ENABLED)
+static int ssl_parse_server_dh_params( mbedtls_ssl_context *ssl,
+                                       unsigned char **p,
+                                       unsigned char *end )
+{
+    int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
+    size_t dhm_actual_bitlen;
+
+    /*
+     * Ephemeral DH parameters:
+     *
+     * struct {
+     *     opaque dh_p<1..2^16-1>;
+     *     opaque dh_g<1..2^16-1>;
+     *     opaque dh_Ys<1..2^16-1>;
+     * } ServerDHParams;
+     */
+    if( ( ret = mbedtls_dhm_read_params( &ssl->handshake->dhm_ctx,
+                                         p, end ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 2, ( "mbedtls_dhm_read_params" ), ret );
+        return( ret );
+    }
+
+    dhm_actual_bitlen = mbedtls_mpi_bitlen( &ssl->handshake->dhm_ctx.P );
+    if( dhm_actual_bitlen < ssl->conf->dhm_min_bitlen )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "DHM prime too short: %" MBEDTLS_PRINTF_SIZET " < %u",
+                                    dhm_actual_bitlen,
+                                    ssl->conf->dhm_min_bitlen ) );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+    }
+
+    MBEDTLS_SSL_DEBUG_MPI( 3, "DHM: P ", &ssl->handshake->dhm_ctx.P  );
+    MBEDTLS_SSL_DEBUG_MPI( 3, "DHM: G ", &ssl->handshake->dhm_ctx.G  );
+    MBEDTLS_SSL_DEBUG_MPI( 3, "DHM: GY", &ssl->handshake->dhm_ctx.GY );
+
+    return( ret );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE_DHE_RSA_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_DHE_PSK_ENABLED */
+
+#if defined(MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED) ||                     \
+    defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED) ||                   \
+    defined(MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED) ||                     \
+    defined(MBEDTLS_KEY_EXCHANGE_ECDH_RSA_ENABLED) ||                      \
+    defined(MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA_ENABLED)
+static int ssl_check_server_ecdh_params( const mbedtls_ssl_context *ssl )
+{
+    const mbedtls_ecp_curve_info *curve_info;
+    mbedtls_ecp_group_id grp_id;
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+    grp_id = ssl->handshake->ecdh_ctx.grp.id;
+#else
+    grp_id = ssl->handshake->ecdh_ctx.grp_id;
+#endif
+
+    curve_info = mbedtls_ecp_curve_info_from_grp_id( grp_id );
+    if( curve_info == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "ECDH curve: %s", curve_info->name ) );
+
+#if defined(MBEDTLS_ECP_C)
+    if( mbedtls_ssl_check_curve( ssl, grp_id ) != 0 )
+#else
+    if( ssl->handshake->ecdh_ctx.grp.nbits < 163 ||
+        ssl->handshake->ecdh_ctx.grp.nbits > 521 )
+#endif
+        return( -1 );
+
+    MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
+                            MBEDTLS_DEBUG_ECDH_QP );
+
+    return( 0 );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_ECDH_RSA_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA_ENABLED */
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO) &&                           \
+        ( defined(MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED) ||     \
+          defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED) )
+static int ssl_parse_server_ecdh_params_psa( mbedtls_ssl_context *ssl,
+                                             unsigned char **p,
+                                             unsigned char *end )
+{
+    uint16_t tls_id;
+    size_t ecdh_bits = 0;
+    uint8_t ecpoint_len;
+    mbedtls_ssl_handshake_params *handshake = ssl->handshake;
+
+    /*
+     * Parse ECC group
+     */
+
+    if( end - *p < 4 )
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+
+    /* First byte is curve_type; only named_curve is handled */
+    if( *(*p)++ != MBEDTLS_ECP_TLS_NAMED_CURVE )
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+
+    /* Next two bytes are the namedcurve value */
+    tls_id = *(*p)++;
+    tls_id <<= 8;
+    tls_id |= *(*p)++;
+
+    /* Convert EC group to PSA key type. */
+    if( ( handshake->ecdh_psa_type =
+          mbedtls_psa_parse_tls_ecc_group( tls_id, &ecdh_bits ) ) == 0 )
+    {
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+    }
+    if( ecdh_bits > 0xffff )
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+    handshake->ecdh_bits = (uint16_t) ecdh_bits;
+
+    /*
+     * Put peer's ECDH public key in the format understood by PSA.
+     */
+
+    ecpoint_len = *(*p)++;
+    if( (size_t)( end - *p ) < ecpoint_len )
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+
+    if( mbedtls_psa_tls_ecpoint_to_psa_ec(
+                                    *p, ecpoint_len,
+                                    handshake->ecdh_psa_peerkey,
+                                    sizeof( handshake->ecdh_psa_peerkey ),
+                                    &handshake->ecdh_psa_peerkey_len ) != 0 )
+    {
+        return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+    }
+
+    *p += ecpoint_len;
+    return( 0 );
+}
+#endif /* MBEDTLS_USE_PSA_CRYPTO &&
+            ( MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED ||
+              MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED ) */
+
+#if defined(MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED) ||                     \
+    defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED) ||                   \
+    defined(MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED)
+static int ssl_parse_server_ecdh_params( mbedtls_ssl_context *ssl,
+                                         unsigned char **p,
+                                         unsigned char *end )
+{
+    int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
+
+    /*
+     * Ephemeral ECDH parameters:
+     *
+     * struct {
+     *     ECParameters curve_params;
+     *     ECPoint      public;
+     * } ServerECDHParams;
+     */
+    if( ( ret = mbedtls_ecdh_read_params( &ssl->handshake->ecdh_ctx,
+                                  (const unsigned char **) p, end ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, ( "mbedtls_ecdh_read_params" ), ret );
+#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
+        if( ret == MBEDTLS_ERR_ECP_IN_PROGRESS )
+            ret = MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS;
+#endif
+        return( ret );
+    }
+
+    if( ssl_check_server_ecdh_params( ssl ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "bad server key exchange message (ECDHE curve)" ) );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+    }
+
+    return( ret );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED */
+
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+static int ssl_parse_server_psk_hint( mbedtls_ssl_context *ssl,
+                                      unsigned char **p,
+                                      unsigned char *end )
+{
+    int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
+    uint16_t  len;
+    ((void) ssl);
+
+    /*
+     * PSK parameters:
+     *
+     * opaque psk_identity_hint<0..2^16-1>;
+     */
+    if( end - (*p) < 2 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "bad server key exchange message (psk_identity_hint length)" ) );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+    }
+    len = (*p)[0] << 8 | (*p)[1];
+    *p += 2;
+
+    if( end - (*p) < len )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "bad server key exchange message (psk_identity_hint length)" ) );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+    }
+
+    /*
+     * Note: we currently ignore the PKS identity hint, as we only allow one
+     * PSK to be provisionned on the client. This could be changed later if
+     * someone needs that feature.
+     */
+    *p += len;
+    ret = 0;
+
+    return( ret );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
+
+#if defined(MBEDTLS_KEY_EXCHANGE_RSA_ENABLED) ||                           \
+    defined(MBEDTLS_KEY_EXCHANGE_RSA_PSK_ENABLED)
+/*
+ * Generate a pre-master secret and encrypt it with the server's RSA key
+ */
+static int ssl_write_encrypted_pms( mbedtls_ssl_context *ssl,
+                                    size_t offset, size_t *olen,
+                                    size_t pms_offset )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    size_t len_bytes = ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 ? 0 : 2;
+    unsigned char *p = ssl->handshake->premaster + pms_offset;
+    mbedtls_pk_context * peer_pk;
+
+    if( offset + len_bytes > MBEDTLS_SSL_OUT_CONTENT_LEN )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "buffer too small for encrypted pms" ) );
+        return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
+    }
+
+    /*
+     * Generate (part of) the pre-master as
+     *  struct {
+     *      ProtocolVersion client_version;
+     *      opaque random[46];
+     *  } PreMasterSecret;
+     */
+    mbedtls_ssl_write_version( ssl->conf->max_major_ver,
+                               ssl->conf->max_minor_ver,
+                               ssl->conf->transport, p );
+
+    if( ( ret = ssl->conf->f_rng( ssl->conf->p_rng, p + 2, 46 ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "f_rng", ret );
+        return( ret );
+    }
+
+    ssl->handshake->pmslen = 48;
+
+#if !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+    peer_pk = &ssl->handshake->peer_pubkey;
+#else /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+    if( ssl->session_negotiate->peer_cert == NULL )
+    {
+        /* Should never happen */
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+    peer_pk = &ssl->session_negotiate->peer_cert->pk;
+#endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+
+    /*
+     * Now write it out, encrypted
+     */
+    if( ! mbedtls_pk_can_do( peer_pk, MBEDTLS_PK_RSA ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "certificate key type mismatch" ) );
+        return( MBEDTLS_ERR_SSL_PK_TYPE_MISMATCH );
+    }
+
+    if( ( ret = mbedtls_pk_encrypt( peer_pk,
+                            p, ssl->handshake->pmslen,
+                            ssl->out_msg + offset + len_bytes, olen,
+                            MBEDTLS_SSL_OUT_CONTENT_LEN - offset - len_bytes,
+                            ssl->conf->f_rng, ssl->conf->p_rng ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_rsa_pkcs1_encrypt", ret );
+        return( ret );
+    }
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_2)
+    if( len_bytes == 2 )
+    {
+        ssl->out_msg[offset+0] = (unsigned char)( *olen >> 8 );
+        ssl->out_msg[offset+1] = (unsigned char)( *olen      );
+        *olen += 2;
+    }
+#endif
+
+#if !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+    /* We don't need the peer's public key anymore. Free it. */
+    mbedtls_pk_free( peer_pk );
+#endif /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+    return( 0 );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE_RSA_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_RSA_PSK_ENABLED */
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+#if defined(MBEDTLS_KEY_EXCHANGE_DHE_RSA_ENABLED) ||                       \
+    defined(MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED) ||                     \
+    defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED)
+static int ssl_parse_signature_algorithm( mbedtls_ssl_context *ssl,
+                                          unsigned char **p,
+                                          unsigned char *end,
+                                          mbedtls_md_type_t *md_alg,
+                                          mbedtls_pk_type_t *pk_alg )
+{
+    ((void) ssl);
+    *md_alg = MBEDTLS_MD_NONE;
+    *pk_alg = MBEDTLS_PK_NONE;
+
+    /* Only in TLS 1.2 */
+    if( ssl->minor_ver != MBEDTLS_SSL_MINOR_VERSION_3 )
+    {
+        return( 0 );
+    }
+
+    if( (*p) + 2 > end )
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+
+    /*
+     * Get hash algorithm
+     */
+    if( ( *md_alg = mbedtls_ssl_md_alg_from_hash( (*p)[0] ) )
+        == MBEDTLS_MD_NONE )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "Server used unsupported HashAlgorithm %d", *(p)[0] ) );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+    }
+
+    /*
+     * Get signature algorithm
+     */
+    if( ( *pk_alg = mbedtls_ssl_pk_alg_from_sig( (*p)[1] ) )
+        == MBEDTLS_PK_NONE )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "server used unsupported SignatureAlgorithm %d", (*p)[1] ) );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+    }
+
+    /*
+     * Check if the hash is acceptable
+     */
+    if( mbedtls_ssl_check_sig_hash( ssl, *md_alg ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "server used HashAlgorithm %d that was not offered", *(p)[0] ) );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "Server used SignatureAlgorithm %d",
+                                (*p)[1] ) );
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "Server used HashAlgorithm %d",
+                                (*p)[0] ) );
+    *p += 2;
+
+    return( 0 );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE_DHE_RSA_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED */
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
+#if defined(MBEDTLS_KEY_EXCHANGE_ECDH_RSA_ENABLED) || \
+    defined(MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA_ENABLED)
+static int ssl_get_ecdh_params_from_cert( mbedtls_ssl_context *ssl )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    const mbedtls_ecp_keypair *peer_key;
+    mbedtls_pk_context * peer_pk;
+
+#if !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+    peer_pk = &ssl->handshake->peer_pubkey;
+#else /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+    if( ssl->session_negotiate->peer_cert == NULL )
+    {
+        /* Should never happen */
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+    peer_pk = &ssl->session_negotiate->peer_cert->pk;
+#endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+
+    if( ! mbedtls_pk_can_do( peer_pk, MBEDTLS_PK_ECKEY ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "server key not ECDH capable" ) );
+        return( MBEDTLS_ERR_SSL_PK_TYPE_MISMATCH );
+    }
+
+    peer_key = mbedtls_pk_ec( *peer_pk );
+
+    if( ( ret = mbedtls_ecdh_get_params( &ssl->handshake->ecdh_ctx, peer_key,
+                                 MBEDTLS_ECDH_THEIRS ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, ( "mbedtls_ecdh_get_params" ), ret );
+        return( ret );
+    }
+
+    if( ssl_check_server_ecdh_params( ssl ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server certificate (ECDH curve)" ) );
+        return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE );
+    }
+
+#if !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+    /* We don't need the peer's public key anymore. Free it,
+     * so that more RAM is available for upcoming expensive
+     * operations like ECDHE. */
+    mbedtls_pk_free( peer_pk );
+#endif /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+
+    return( ret );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE_ECDH_RSA_ENABLED) ||
+          MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA_ENABLED */
+
+static int ssl_parse_server_key_exchange( mbedtls_ssl_context *ssl )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
+        ssl->handshake->ciphersuite_info;
+    unsigned char *p = NULL, *end = NULL;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse server key exchange" ) );
+
+#if defined(MBEDTLS_KEY_EXCHANGE_RSA_ENABLED)
+    if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_RSA )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip parse server key exchange" ) );
+        ssl->state++;
+        return( 0 );
+    }
+    ((void) p);
+    ((void) end);
+#endif
+
+#if defined(MBEDTLS_KEY_EXCHANGE_ECDH_RSA_ENABLED) || \
+    defined(MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA_ENABLED)
+    if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDH_RSA ||
+        ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA )
+    {
+        if( ( ret = ssl_get_ecdh_params_from_cert( ssl ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "ssl_get_ecdh_params_from_cert", ret );
+            mbedtls_ssl_send_alert_message(
+                ssl,
+                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE );
+            return( ret );
+        }
+
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip parse server key exchange" ) );
+        ssl->state++;
+        return( 0 );
+    }
+    ((void) p);
+    ((void) end);
+#endif /* MBEDTLS_KEY_EXCHANGE_ECDH_RSA_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA_ENABLED */
+
+#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
+    if( ssl->handshake->ecrs_enabled &&
+        ssl->handshake->ecrs_state == ssl_ecrs_ske_start_processing )
+    {
+        goto start_processing;
+    }
+#endif
+
+    if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
+        return( ret );
+    }
+
+    if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server key exchange message" ) );
+        mbedtls_ssl_send_alert_message(
+            ssl,
+            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+            MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
+        return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+    }
+
+    /*
+     * ServerKeyExchange may be skipped with PSK and RSA-PSK when the server
+     * doesn't use a psk_identity_hint
+     */
+    if( ssl->in_msg[0] != MBEDTLS_SSL_HS_SERVER_KEY_EXCHANGE )
+    {
+        if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK ||
+            ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_RSA_PSK )
+        {
+            /* Current message is probably either
+             * CertificateRequest or ServerHelloDone */
+            ssl->keep_current_message = 1;
+            goto exit;
+        }
+
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "server key exchange message must not be skipped" ) );
+        mbedtls_ssl_send_alert_message(
+            ssl,
+            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+            MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
+
+        return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+    }
+
+#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
+    if( ssl->handshake->ecrs_enabled )
+        ssl->handshake->ecrs_state = ssl_ecrs_ske_start_processing;
+
+start_processing:
+#endif
+    p   = ssl->in_msg + mbedtls_ssl_hs_hdr_len( ssl );
+    end = ssl->in_msg + ssl->in_hslen;
+    MBEDTLS_SSL_DEBUG_BUF( 3,   "server key exchange", p, end - p );
+
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+    if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK ||
+        ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_RSA_PSK ||
+        ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_DHE_PSK ||
+        ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_PSK )
+    {
+        if( ssl_parse_server_psk_hint( ssl, &p, end ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server key exchange message" ) );
+            mbedtls_ssl_send_alert_message(
+                ssl,
+                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
+            return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+        }
+    } /* FALLTROUGH */
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
+
+#if defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED) ||                       \
+    defined(MBEDTLS_KEY_EXCHANGE_RSA_PSK_ENABLED)
+    if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK ||
+        ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_RSA_PSK )
+        ; /* nothing more to do */
+    else
+#endif /* MBEDTLS_KEY_EXCHANGE_PSK_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_RSA_PSK_ENABLED */
+#if defined(MBEDTLS_KEY_EXCHANGE_DHE_RSA_ENABLED) ||                       \
+    defined(MBEDTLS_KEY_EXCHANGE_DHE_PSK_ENABLED)
+    if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_DHE_RSA ||
+        ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_DHE_PSK )
+    {
+        if( ssl_parse_server_dh_params( ssl, &p, end ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server key exchange message" ) );
+            mbedtls_ssl_send_alert_message(
+                ssl,
+                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
+            return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+        }
+    }
+    else
+#endif /* MBEDTLS_KEY_EXCHANGE_DHE_RSA_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_DHE_PSK_ENABLED */
+#if defined(MBEDTLS_USE_PSA_CRYPTO) &&                           \
+        ( defined(MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED) ||     \
+          defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED) )
+    if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_RSA ||
+        ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA )
+    {
+        if( ssl_parse_server_ecdh_params_psa( ssl, &p, end ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server key exchange message" ) );
+            mbedtls_ssl_send_alert_message(
+                ssl,
+                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
+            return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+        }
+    }
+    else
+#endif /* MBEDTLS_USE_PSA_CRYPTO &&
+            ( MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED ||
+              MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED ) */
+#if defined(MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED) ||                     \
+    defined(MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED) ||                     \
+    defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED)
+    if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_RSA ||
+        ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_PSK ||
+        ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA )
+    {
+        if( ssl_parse_server_ecdh_params( ssl, &p, end ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server key exchange message" ) );
+            mbedtls_ssl_send_alert_message(
+                ssl,
+                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
+            return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+        }
+    }
+    else
+#endif /* MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED */
+#if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+    if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECJPAKE )
+    {
+        ret = mbedtls_ecjpake_read_round_two( &ssl->handshake->ecjpake_ctx,
+                                              p, end - p );
+        if( ret != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecjpake_read_round_two", ret );
+            mbedtls_ssl_send_alert_message(
+                ssl,
+                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
+            return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+        }
+    }
+    else
+#endif /* MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+#if defined(MBEDTLS_KEY_EXCHANGE_WITH_SERVER_SIGNATURE_ENABLED)
+    if( mbedtls_ssl_ciphersuite_uses_server_signature( ciphersuite_info ) )
+    {
+        size_t sig_len, hashlen;
+        unsigned char hash[64];
+        mbedtls_md_type_t md_alg = MBEDTLS_MD_NONE;
+        mbedtls_pk_type_t pk_alg = MBEDTLS_PK_NONE;
+        unsigned char *params = ssl->in_msg + mbedtls_ssl_hs_hdr_len( ssl );
+        size_t params_len = p - params;
+        void *rs_ctx = NULL;
+
+        mbedtls_pk_context * peer_pk;
+
+        /*
+         * Handle the digitally-signed structure
+         */
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+        if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
+        {
+            if( ssl_parse_signature_algorithm( ssl, &p, end,
+                                               &md_alg, &pk_alg ) != 0 )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1,
+                    ( "bad server key exchange message" ) );
+                mbedtls_ssl_send_alert_message(
+                    ssl,
+                    MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                    MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
+                return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+            }
+
+            if( pk_alg !=
+                mbedtls_ssl_get_ciphersuite_sig_pk_alg( ciphersuite_info ) )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1,
+                    ( "bad server key exchange message" ) );
+                mbedtls_ssl_send_alert_message(
+                    ssl,
+                    MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                    MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
+                return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+            }
+        }
+        else
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_1)
+        if( ssl->minor_ver < MBEDTLS_SSL_MINOR_VERSION_3 )
+        {
+            pk_alg = mbedtls_ssl_get_ciphersuite_sig_pk_alg( ciphersuite_info );
+
+            /* Default hash for ECDSA is SHA-1 */
+            if( pk_alg == MBEDTLS_PK_ECDSA && md_alg == MBEDTLS_MD_NONE )
+                md_alg = MBEDTLS_MD_SHA1;
+        }
+        else
+#endif
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+
+        /*
+         * Read signature
+         */
+
+        if( p > end - 2 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server key exchange message" ) );
+            mbedtls_ssl_send_alert_message(
+                ssl,
+                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+            return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+        }
+        sig_len = ( p[0] << 8 ) | p[1];
+        p += 2;
+
+        if( p != end - sig_len )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server key exchange message" ) );
+            mbedtls_ssl_send_alert_message(
+                ssl,
+                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+            return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+        }
+
+        MBEDTLS_SSL_DEBUG_BUF( 3, "signature", p, sig_len );
+
+        /*
+         * Compute the hash that has been signed
+         */
+#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_1)
+        if( md_alg == MBEDTLS_MD_NONE )
+        {
+            hashlen = 36;
+            ret = mbedtls_ssl_get_key_exchange_md_ssl_tls( ssl, hash, params,
+                                                           params_len );
+            if( ret != 0 )
+                return( ret );
+        }
+        else
+#endif /* MBEDTLS_SSL_PROTO_SSL3 || MBEDTLS_SSL_PROTO_TLS1 || \
+          MBEDTLS_SSL_PROTO_TLS1_1 */
+#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_2)
+        if( md_alg != MBEDTLS_MD_NONE )
+        {
+            ret = mbedtls_ssl_get_key_exchange_md_tls1_2( ssl, hash, &hashlen,
+                                                          params, params_len,
+                                                          md_alg );
+            if( ret != 0 )
+                return( ret );
+        }
+        else
+#endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 || \
+          MBEDTLS_SSL_PROTO_TLS1_2 */
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+
+        MBEDTLS_SSL_DEBUG_BUF( 3, "parameters hash", hash, hashlen );
+
+#if !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+        peer_pk = &ssl->handshake->peer_pubkey;
+#else /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+        if( ssl->session_negotiate->peer_cert == NULL )
+        {
+            /* Should never happen */
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+        peer_pk = &ssl->session_negotiate->peer_cert->pk;
+#endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+
+        /*
+         * Verify signature
+         */
+        if( !mbedtls_pk_can_do( peer_pk, pk_alg ) )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server key exchange message" ) );
+            mbedtls_ssl_send_alert_message(
+                ssl,
+                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE );
+            return( MBEDTLS_ERR_SSL_PK_TYPE_MISMATCH );
+        }
+
+#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
+        if( ssl->handshake->ecrs_enabled )
+            rs_ctx = &ssl->handshake->ecrs_ctx.pk;
+#endif
+
+        if( ( ret = mbedtls_pk_verify_restartable( peer_pk,
+                        md_alg, hash, hashlen, p, sig_len, rs_ctx ) ) != 0 )
+        {
+#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
+            if( ret != MBEDTLS_ERR_ECP_IN_PROGRESS )
+#endif
+                mbedtls_ssl_send_alert_message(
+                    ssl,
+                    MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                    MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR );
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_pk_verify", ret );
+#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
+            if( ret == MBEDTLS_ERR_ECP_IN_PROGRESS )
+                ret = MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS;
+#endif
+            return( ret );
+        }
+
+#if !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+        /* We don't need the peer's public key anymore. Free it,
+         * so that more RAM is available for upcoming expensive
+         * operations like ECDHE. */
+        mbedtls_pk_free( peer_pk );
+#endif /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+    }
+#endif /* MBEDTLS_KEY_EXCHANGE_WITH_SERVER_SIGNATURE_ENABLED */
+
+exit:
+    ssl->state++;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse server key exchange" ) );
+
+    return( 0 );
+}
+
+#if ! defined(MBEDTLS_KEY_EXCHANGE_CERT_REQ_ALLOWED_ENABLED)
+static int ssl_parse_certificate_request( mbedtls_ssl_context *ssl )
+{
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
+        ssl->handshake->ciphersuite_info;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate request" ) );
+
+    if( ! mbedtls_ssl_ciphersuite_cert_req_allowed( ciphersuite_info ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip parse certificate request" ) );
+        ssl->state++;
+        return( 0 );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+    return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+}
+#else /* MBEDTLS_KEY_EXCHANGE_CERT_REQ_ALLOWED_ENABLED */
+static int ssl_parse_certificate_request( mbedtls_ssl_context *ssl )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    unsigned char *buf;
+    size_t n = 0;
+    size_t cert_type_len = 0, dn_len = 0;
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
+        ssl->handshake->ciphersuite_info;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate request" ) );
+
+    if( ! mbedtls_ssl_ciphersuite_cert_req_allowed( ciphersuite_info ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip parse certificate request" ) );
+        ssl->state++;
+        return( 0 );
+    }
+
+    if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
+        return( ret );
+    }
+
+    if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate request message" ) );
+        mbedtls_ssl_send_alert_message(
+            ssl,
+            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+            MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
+        return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+    }
+
+    ssl->state++;
+    ssl->client_auth = ( ssl->in_msg[0] == MBEDTLS_SSL_HS_CERTIFICATE_REQUEST );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "got %s certificate request",
+                        ssl->client_auth ? "a" : "no" ) );
+
+    if( ssl->client_auth == 0 )
+    {
+        /* Current message is probably the ServerHelloDone */
+        ssl->keep_current_message = 1;
+        goto exit;
+    }
+
+    /*
+     *  struct {
+     *      ClientCertificateType certificate_types<1..2^8-1>;
+     *      SignatureAndHashAlgorithm
+     *        supported_signature_algorithms<2^16-1>; -- TLS 1.2 only
+     *      DistinguishedName certificate_authorities<0..2^16-1>;
+     *  } CertificateRequest;
+     *
+     *  Since we only support a single certificate on clients, let's just
+     *  ignore all the information that's supposed to help us pick a
+     *  certificate.
+     *
+     *  We could check that our certificate matches the request, and bail out
+     *  if it doesn't, but it's simpler to just send the certificate anyway,
+     *  and give the server the opportunity to decide if it should terminate
+     *  the connection when it doesn't like our certificate.
+     *
+     *  Same goes for the hash in TLS 1.2's signature_algorithms: at this
+     *  point we only have one hash available (see comments in
+     *  write_certificate_verify), so let's just use what we have.
+     *
+     *  However, we still minimally parse the message to check it is at least
+     *  superficially sane.
+     */
+    buf = ssl->in_msg;
+
+    /* certificate_types */
+    if( ssl->in_hslen <= mbedtls_ssl_hs_hdr_len( ssl ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate request message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE_REQUEST );
+    }
+    cert_type_len = buf[mbedtls_ssl_hs_hdr_len( ssl )];
+    n = cert_type_len;
+
+    /*
+     * In the subsequent code there are two paths that read from buf:
+     *     * the length of the signature algorithms field (if minor version of
+     *       SSL is 3),
+     *     * distinguished name length otherwise.
+     * Both reach at most the index:
+     *    ...hdr_len + 2 + n,
+     * therefore the buffer length at this point must be greater than that
+     * regardless of the actual code path.
+     */
+    if( ssl->in_hslen <= mbedtls_ssl_hs_hdr_len( ssl ) + 2 + n )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate request message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE_REQUEST );
+    }
+
+    /* supported_signature_algorithms */
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+    if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
+    {
+        size_t sig_alg_len =
+            ( ( buf[mbedtls_ssl_hs_hdr_len( ssl ) + 1 + n] <<  8 )
+              | ( buf[mbedtls_ssl_hs_hdr_len( ssl ) + 2 + n]   ) );
+#if defined(MBEDTLS_DEBUG_C)
+        unsigned char* sig_alg;
+        size_t i;
+#endif
+
+        /*
+         * The furthest access in buf is in the loop few lines below:
+         *     sig_alg[i + 1],
+         * where:
+         *     sig_alg = buf + ...hdr_len + 3 + n,
+         *     max(i) = sig_alg_len - 1.
+         * Therefore the furthest access is:
+         *     buf[...hdr_len + 3 + n + sig_alg_len - 1 + 1],
+         * which reduces to:
+         *     buf[...hdr_len + 3 + n + sig_alg_len],
+         * which is one less than we need the buf to be.
+         */
+        if( ssl->in_hslen <= mbedtls_ssl_hs_hdr_len( ssl )
+                                + 3 + n + sig_alg_len )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate request message" ) );
+            mbedtls_ssl_send_alert_message(
+                ssl,
+                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+            return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE_REQUEST );
+        }
+
+#if defined(MBEDTLS_DEBUG_C)
+        sig_alg = buf + mbedtls_ssl_hs_hdr_len( ssl ) + 3 + n;
+        for( i = 0; i < sig_alg_len; i += 2 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 3,
+                ( "Supported Signature Algorithm found: %d,%d",
+                  sig_alg[i], sig_alg[i + 1]  ) );
+        }
+#endif
+
+        n += 2 + sig_alg_len;
+    }
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
+    /* certificate_authorities */
+    dn_len = ( ( buf[mbedtls_ssl_hs_hdr_len( ssl ) + 1 + n] <<  8 )
+             | ( buf[mbedtls_ssl_hs_hdr_len( ssl ) + 2 + n]       ) );
+
+    n += dn_len;
+    if( ssl->in_hslen != mbedtls_ssl_hs_hdr_len( ssl ) + 3 + n )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate request message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE_REQUEST );
+    }
+
+exit:
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse certificate request" ) );
+
+    return( 0 );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE_CERT_REQ_ALLOWED_ENABLED */
+
+static int ssl_parse_server_hello_done( mbedtls_ssl_context *ssl )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse server hello done" ) );
+
+    if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
+        return( ret );
+    }
+
+    if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello done message" ) );
+        return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+    }
+
+    if( ssl->in_hslen  != mbedtls_ssl_hs_hdr_len( ssl ) ||
+        ssl->in_msg[0] != MBEDTLS_SSL_HS_SERVER_HELLO_DONE )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello done message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO_DONE );
+    }
+
+    ssl->state++;
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+        mbedtls_ssl_recv_flight_completed( ssl );
+#endif
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse server hello done" ) );
+
+    return( 0 );
+}
+
+static int ssl_write_client_key_exchange( mbedtls_ssl_context *ssl )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    size_t header_len;
+    size_t content_len;
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
+        ssl->handshake->ciphersuite_info;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write client key exchange" ) );
+
+#if defined(MBEDTLS_KEY_EXCHANGE_DHE_RSA_ENABLED)
+    if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_DHE_RSA )
+    {
+        /*
+         * DHM key exchange -- send G^X mod P
+         */
+        content_len = ssl->handshake->dhm_ctx.len;
+
+        ssl->out_msg[4] = (unsigned char)( content_len >> 8 );
+        ssl->out_msg[5] = (unsigned char)( content_len      );
+        header_len = 6;
+
+        ret = mbedtls_dhm_make_public( &ssl->handshake->dhm_ctx,
+                          (int) mbedtls_mpi_size( &ssl->handshake->dhm_ctx.P ),
+                          &ssl->out_msg[header_len], content_len,
+                          ssl->conf->f_rng, ssl->conf->p_rng );
+        if( ret != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_dhm_make_public", ret );
+            return( ret );
+        }
+
+        MBEDTLS_SSL_DEBUG_MPI( 3, "DHM: X ", &ssl->handshake->dhm_ctx.X  );
+        MBEDTLS_SSL_DEBUG_MPI( 3, "DHM: GX", &ssl->handshake->dhm_ctx.GX );
+
+        if( ( ret = mbedtls_dhm_calc_secret( &ssl->handshake->dhm_ctx,
+                                  ssl->handshake->premaster,
+                                  MBEDTLS_PREMASTER_SIZE,
+                                  &ssl->handshake->pmslen,
+                                  ssl->conf->f_rng, ssl->conf->p_rng ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_dhm_calc_secret", ret );
+            return( ret );
+        }
+
+        MBEDTLS_SSL_DEBUG_MPI( 3, "DHM: K ", &ssl->handshake->dhm_ctx.K  );
+    }
+    else
+#endif /* MBEDTLS_KEY_EXCHANGE_DHE_RSA_ENABLED */
+#if defined(MBEDTLS_USE_PSA_CRYPTO) &&                           \
+        ( defined(MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED) ||     \
+          defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED) )
+    if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_RSA ||
+        ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA )
+    {
+        psa_status_t status;
+        psa_key_attributes_t key_attributes;
+
+        mbedtls_ssl_handshake_params *handshake = ssl->handshake;
+
+        unsigned char own_pubkey[MBEDTLS_PSA_MAX_EC_PUBKEY_LENGTH];
+        size_t own_pubkey_len;
+        unsigned char *own_pubkey_ecpoint;
+        size_t own_pubkey_ecpoint_len;
+
+        header_len = 4;
+
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "Perform PSA-based ECDH computation." ) );
+
+        /*
+         * Generate EC private key for ECDHE exchange.
+         */
+
+        /* The master secret is obtained from the shared ECDH secret by
+         * applying the TLS 1.2 PRF with a specific salt and label. While
+         * the PSA Crypto API encourages combining key agreement schemes
+         * such as ECDH with fixed KDFs such as TLS 1.2 PRF, it does not
+         * yet support the provisioning of salt + label to the KDF.
+         * For the time being, we therefore need to split the computation
+         * of the ECDH secret and the application of the TLS 1.2 PRF. */
+        key_attributes = psa_key_attributes_init();
+        psa_set_key_usage_flags( &key_attributes, PSA_KEY_USAGE_DERIVE );
+        psa_set_key_algorithm( &key_attributes, PSA_ALG_ECDH );
+        psa_set_key_type( &key_attributes, handshake->ecdh_psa_type );
+        psa_set_key_bits( &key_attributes, handshake->ecdh_bits );
+
+        /* Generate ECDH private key. */
+        status = psa_generate_key( &key_attributes,
+                                   &handshake->ecdh_psa_privkey );
+        if( status != PSA_SUCCESS )
+            return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+
+        /* Export the public part of the ECDH private key from PSA
+         * and convert it to ECPoint format used in ClientKeyExchange. */
+        status = psa_export_public_key( handshake->ecdh_psa_privkey,
+                                        own_pubkey, sizeof( own_pubkey ),
+                                        &own_pubkey_len );
+        if( status != PSA_SUCCESS )
+            return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+
+        if( mbedtls_psa_tls_psa_ec_to_ecpoint( own_pubkey,
+                                               own_pubkey_len,
+                                               &own_pubkey_ecpoint,
+                                               &own_pubkey_ecpoint_len ) != 0 )
+        {
+            return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+        }
+
+        /* Copy ECPoint structure to outgoing message buffer. */
+        ssl->out_msg[header_len] = (unsigned char) own_pubkey_ecpoint_len;
+        memcpy( ssl->out_msg + header_len + 1,
+                own_pubkey_ecpoint, own_pubkey_ecpoint_len );
+        content_len = own_pubkey_ecpoint_len + 1;
+
+        /* The ECDH secret is the premaster secret used for key derivation. */
+
+        /* Compute ECDH shared secret. */
+        status = psa_raw_key_agreement( PSA_ALG_ECDH,
+                                        handshake->ecdh_psa_privkey,
+                                        handshake->ecdh_psa_peerkey,
+                                        handshake->ecdh_psa_peerkey_len,
+                                        ssl->handshake->premaster,
+                                        sizeof( ssl->handshake->premaster ),
+                                        &ssl->handshake->pmslen );
+        if( status != PSA_SUCCESS )
+            return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+
+        status = psa_destroy_key( handshake->ecdh_psa_privkey );
+        if( status != PSA_SUCCESS )
+            return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+        handshake->ecdh_psa_privkey = MBEDTLS_SVC_KEY_ID_INIT;
+    }
+    else
+#endif /* MBEDTLS_USE_PSA_CRYPTO &&
+            ( MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED ||
+              MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED ) */
+#if defined(MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED) ||                     \
+    defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED) ||                   \
+    defined(MBEDTLS_KEY_EXCHANGE_ECDH_RSA_ENABLED) ||                      \
+    defined(MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA_ENABLED)
+    if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_RSA ||
+        ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA ||
+        ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDH_RSA ||
+        ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA )
+    {
+        /*
+         * ECDH key exchange -- send client public value
+         */
+        header_len = 4;
+
+#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
+        if( ssl->handshake->ecrs_enabled )
+        {
+            if( ssl->handshake->ecrs_state == ssl_ecrs_cke_ecdh_calc_secret )
+                goto ecdh_calc_secret;
+
+            mbedtls_ecdh_enable_restart( &ssl->handshake->ecdh_ctx );
+        }
+#endif
+
+        ret = mbedtls_ecdh_make_public( &ssl->handshake->ecdh_ctx,
+                                &content_len,
+                                &ssl->out_msg[header_len], 1000,
+                                ssl->conf->f_rng, ssl->conf->p_rng );
+        if( ret != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_make_public", ret );
+#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
+            if( ret == MBEDTLS_ERR_ECP_IN_PROGRESS )
+                ret = MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS;
+#endif
+            return( ret );
+        }
+
+        MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
+                                MBEDTLS_DEBUG_ECDH_Q );
+
+#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
+        if( ssl->handshake->ecrs_enabled )
+        {
+            ssl->handshake->ecrs_n = content_len;
+            ssl->handshake->ecrs_state = ssl_ecrs_cke_ecdh_calc_secret;
+        }
+
+ecdh_calc_secret:
+        if( ssl->handshake->ecrs_enabled )
+            content_len = ssl->handshake->ecrs_n;
+#endif
+        if( ( ret = mbedtls_ecdh_calc_secret( &ssl->handshake->ecdh_ctx,
+                                  &ssl->handshake->pmslen,
+                                  ssl->handshake->premaster,
+                                  MBEDTLS_MPI_MAX_SIZE,
+                                  ssl->conf->f_rng, ssl->conf->p_rng ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_calc_secret", ret );
+#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
+            if( ret == MBEDTLS_ERR_ECP_IN_PROGRESS )
+                ret = MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS;
+#endif
+            return( ret );
+        }
+
+        MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
+                                MBEDTLS_DEBUG_ECDH_Z );
+    }
+    else
+#endif /* MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_ECDH_RSA_ENABLED ||
+          MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA_ENABLED */
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+    if( mbedtls_ssl_ciphersuite_uses_psk( ciphersuite_info ) )
+    {
+        /*
+         * opaque psk_identity<0..2^16-1>;
+         */
+        if( ssl_conf_has_static_psk( ssl->conf ) == 0 )
+        {
+            /* We don't offer PSK suites if we don't have a PSK,
+             * and we check that the server's choice is among the
+             * ciphersuites we offered, so this should never happen. */
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+
+        header_len = 4;
+        content_len = ssl->conf->psk_identity_len;
+
+        if( header_len + 2 + content_len > MBEDTLS_SSL_OUT_CONTENT_LEN )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1,
+                ( "psk identity too long or SSL buffer too short" ) );
+            return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
+        }
+
+        ssl->out_msg[header_len++] = (unsigned char)( content_len >> 8 );
+        ssl->out_msg[header_len++] = (unsigned char)( content_len      );
+
+        memcpy( ssl->out_msg + header_len,
+                ssl->conf->psk_identity,
+                ssl->conf->psk_identity_len );
+        header_len += ssl->conf->psk_identity_len;
+
+#if defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED)
+        if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK )
+        {
+            content_len = 0;
+        }
+        else
+#endif
+#if defined(MBEDTLS_KEY_EXCHANGE_RSA_PSK_ENABLED)
+        if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_RSA_PSK )
+        {
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+            /* Opaque PSKs are currently only supported for PSK-only suites. */
+            if( ssl_conf_has_static_raw_psk( ssl->conf ) == 0 )
+                return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+            if( ( ret = ssl_write_encrypted_pms( ssl, header_len,
+                                                 &content_len, 2 ) ) != 0 )
+                return( ret );
+        }
+        else
+#endif
+#if defined(MBEDTLS_KEY_EXCHANGE_DHE_PSK_ENABLED)
+        if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_DHE_PSK )
+        {
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+            /* Opaque PSKs are currently only supported for PSK-only suites. */
+            if( ssl_conf_has_static_raw_psk( ssl->conf ) == 0 )
+                return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+            /*
+             * ClientDiffieHellmanPublic public (DHM send G^X mod P)
+             */
+            content_len = ssl->handshake->dhm_ctx.len;
+
+            if( header_len + 2 + content_len >
+                MBEDTLS_SSL_OUT_CONTENT_LEN )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1,
+                    ( "psk identity or DHM size too long or SSL buffer too short" ) );
+                return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
+            }
+
+            ssl->out_msg[header_len++] = (unsigned char)( content_len >> 8 );
+            ssl->out_msg[header_len++] = (unsigned char)( content_len      );
+
+            ret = mbedtls_dhm_make_public( &ssl->handshake->dhm_ctx,
+                    (int) mbedtls_mpi_size( &ssl->handshake->dhm_ctx.P ),
+                    &ssl->out_msg[header_len], content_len,
+                    ssl->conf->f_rng, ssl->conf->p_rng );
+            if( ret != 0 )
+            {
+                MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_dhm_make_public", ret );
+                return( ret );
+            }
+        }
+        else
+#endif /* MBEDTLS_KEY_EXCHANGE_DHE_PSK_ENABLED */
+#if defined(MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED)
+        if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_PSK )
+        {
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+            /* Opaque PSKs are currently only supported for PSK-only suites. */
+            if( ssl_conf_has_static_raw_psk( ssl->conf ) == 0 )
+                return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+            /*
+             * ClientECDiffieHellmanPublic public;
+             */
+            ret = mbedtls_ecdh_make_public( &ssl->handshake->ecdh_ctx,
+                    &content_len,
+                    &ssl->out_msg[header_len],
+                    MBEDTLS_SSL_OUT_CONTENT_LEN - header_len,
+                    ssl->conf->f_rng, ssl->conf->p_rng );
+            if( ret != 0 )
+            {
+                MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_make_public", ret );
+                return( ret );
+            }
+
+            MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
+                                    MBEDTLS_DEBUG_ECDH_Q );
+        }
+        else
+#endif /* MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED */
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO) &&          \
+    defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED)
+        if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK &&
+            ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 &&
+            ssl_conf_has_static_raw_psk( ssl->conf ) == 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1,
+                ( "skip PMS generation for opaque PSK" ) );
+        }
+        else
+#endif /* MBEDTLS_USE_PSA_CRYPTO &&
+          MBEDTLS_KEY_EXCHANGE_PSK_ENABLED */
+        if( ( ret = mbedtls_ssl_psk_derive_premaster( ssl,
+                        ciphersuite_info->key_exchange ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1,
+                "mbedtls_ssl_psk_derive_premaster", ret );
+            return( ret );
+        }
+    }
+    else
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
+#if defined(MBEDTLS_KEY_EXCHANGE_RSA_ENABLED)
+    if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_RSA )
+    {
+        header_len = 4;
+        if( ( ret = ssl_write_encrypted_pms( ssl, header_len,
+                                             &content_len, 0 ) ) != 0 )
+            return( ret );
+    }
+    else
+#endif /* MBEDTLS_KEY_EXCHANGE_RSA_ENABLED */
+#if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
+    if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECJPAKE )
+    {
+        header_len = 4;
+
+        ret = mbedtls_ecjpake_write_round_two( &ssl->handshake->ecjpake_ctx,
+                ssl->out_msg + header_len,
+                MBEDTLS_SSL_OUT_CONTENT_LEN - header_len,
+                &content_len,
+                ssl->conf->f_rng, ssl->conf->p_rng );
+        if( ret != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecjpake_write_round_two", ret );
+            return( ret );
+        }
+
+        ret = mbedtls_ecjpake_derive_secret( &ssl->handshake->ecjpake_ctx,
+                ssl->handshake->premaster, 32, &ssl->handshake->pmslen,
+                ssl->conf->f_rng, ssl->conf->p_rng );
+        if( ret != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecjpake_derive_secret", ret );
+            return( ret );
+        }
+    }
+    else
+#endif /* MBEDTLS_KEY_EXCHANGE_RSA_ENABLED */
+    {
+        ((void) ciphersuite_info);
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    ssl->out_msglen  = header_len + content_len;
+    ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
+    ssl->out_msg[0]  = MBEDTLS_SSL_HS_CLIENT_KEY_EXCHANGE;
+
+    ssl->state++;
+
+    if( ( ret = mbedtls_ssl_write_handshake_msg( ssl ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_handshake_msg", ret );
+        return( ret );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write client key exchange" ) );
+
+    return( 0 );
+}
+
+#if !defined(MBEDTLS_KEY_EXCHANGE_CERT_REQ_ALLOWED_ENABLED)
+static int ssl_write_certificate_verify( mbedtls_ssl_context *ssl )
+{
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
+        ssl->handshake->ciphersuite_info;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write certificate verify" ) );
+
+    if( ( ret = mbedtls_ssl_derive_keys( ssl ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_derive_keys", ret );
+        return( ret );
+    }
+
+    if( !mbedtls_ssl_ciphersuite_cert_req_allowed( ciphersuite_info ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip write certificate verify" ) );
+        ssl->state++;
+        return( 0 );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+    return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+}
+#else /* !MBEDTLS_KEY_EXCHANGE_CERT_REQ_ALLOWED_ENABLED */
+static int ssl_write_certificate_verify( mbedtls_ssl_context *ssl )
+{
+    int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
+        ssl->handshake->ciphersuite_info;
+    size_t n = 0, offset = 0;
+    unsigned char hash[48];
+    unsigned char *hash_start = hash;
+    mbedtls_md_type_t md_alg = MBEDTLS_MD_NONE;
+    size_t hashlen;
+    void *rs_ctx = NULL;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write certificate verify" ) );
+
+#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
+    if( ssl->handshake->ecrs_enabled &&
+        ssl->handshake->ecrs_state == ssl_ecrs_crt_vrfy_sign )
+    {
+        goto sign;
+    }
+#endif
+
+    if( ( ret = mbedtls_ssl_derive_keys( ssl ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_derive_keys", ret );
+        return( ret );
+    }
+
+    if( !mbedtls_ssl_ciphersuite_cert_req_allowed( ciphersuite_info ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip write certificate verify" ) );
+        ssl->state++;
+        return( 0 );
+    }
+
+    if( ssl->client_auth == 0 || mbedtls_ssl_own_cert( ssl ) == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip write certificate verify" ) );
+        ssl->state++;
+        return( 0 );
+    }
+
+    if( mbedtls_ssl_own_key( ssl ) == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "got no private key for certificate" ) );
+        return( MBEDTLS_ERR_SSL_PRIVATE_KEY_REQUIRED );
+    }
+
+    /*
+     * Make a signature of the handshake digests
+     */
+#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
+    if( ssl->handshake->ecrs_enabled )
+        ssl->handshake->ecrs_state = ssl_ecrs_crt_vrfy_sign;
+
+sign:
+#endif
+
+    ssl->handshake->calc_verify( ssl, hash, &hashlen );
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_1)
+    if( ssl->minor_ver != MBEDTLS_SSL_MINOR_VERSION_3 )
+    {
+        /*
+         * digitally-signed struct {
+         *     opaque md5_hash[16];
+         *     opaque sha_hash[20];
+         * };
+         *
+         * md5_hash
+         *     MD5(handshake_messages);
+         *
+         * sha_hash
+         *     SHA(handshake_messages);
+         */
+        md_alg = MBEDTLS_MD_NONE;
+
+        /*
+         * For ECDSA, default hash is SHA-1 only
+         */
+        if( mbedtls_pk_can_do( mbedtls_ssl_own_key( ssl ), MBEDTLS_PK_ECDSA ) )
+        {
+            hash_start += 16;
+            hashlen -= 16;
+            md_alg = MBEDTLS_MD_SHA1;
+        }
+    }
+    else
+#endif /* MBEDTLS_SSL_PROTO_SSL3 || MBEDTLS_SSL_PROTO_TLS1 || \
+          MBEDTLS_SSL_PROTO_TLS1_1 */
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+    if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
+    {
+        /*
+         * digitally-signed struct {
+         *     opaque handshake_messages[handshake_messages_length];
+         * };
+         *
+         * Taking shortcut here. We assume that the server always allows the
+         * PRF Hash function and has sent it in the allowed signature
+         * algorithms list received in the Certificate Request message.
+         *
+         * Until we encounter a server that does not, we will take this
+         * shortcut.
+         *
+         * Reason: Otherwise we should have running hashes for SHA512 and
+         *         SHA224 in order to satisfy 'weird' needs from the server
+         *         side.
+         */
+        if( ssl->handshake->ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
+        {
+            md_alg = MBEDTLS_MD_SHA384;
+            ssl->out_msg[4] = MBEDTLS_SSL_HASH_SHA384;
+        }
+        else
+        {
+            md_alg = MBEDTLS_MD_SHA256;
+            ssl->out_msg[4] = MBEDTLS_SSL_HASH_SHA256;
+        }
+        ssl->out_msg[5] = mbedtls_ssl_sig_from_pk( mbedtls_ssl_own_key( ssl ) );
+
+        /* Info from md_alg will be used instead */
+        hashlen = 0;
+        offset = 2;
+    }
+    else
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
+    if( ssl->handshake->ecrs_enabled )
+        rs_ctx = &ssl->handshake->ecrs_ctx.pk;
+#endif
+
+    if( ( ret = mbedtls_pk_sign_restartable( mbedtls_ssl_own_key( ssl ),
+                         md_alg, hash_start, hashlen,
+                         ssl->out_msg + 6 + offset, &n,
+                         ssl->conf->f_rng, ssl->conf->p_rng, rs_ctx ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_pk_sign", ret );
+#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
+        if( ret == MBEDTLS_ERR_ECP_IN_PROGRESS )
+            ret = MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS;
+#endif
+        return( ret );
+    }
+
+    ssl->out_msg[4 + offset] = (unsigned char)( n >> 8 );
+    ssl->out_msg[5 + offset] = (unsigned char)( n      );
+
+    ssl->out_msglen  = 6 + n + offset;
+    ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
+    ssl->out_msg[0]  = MBEDTLS_SSL_HS_CERTIFICATE_VERIFY;
+
+    ssl->state++;
+
+    if( ( ret = mbedtls_ssl_write_handshake_msg( ssl ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_handshake_msg", ret );
+        return( ret );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write certificate verify" ) );
+
+    return( ret );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE_CERT_REQ_ALLOWED_ENABLED */
+
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+static int ssl_parse_new_session_ticket( mbedtls_ssl_context *ssl )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    uint32_t lifetime;
+    size_t ticket_len;
+    unsigned char *ticket;
+    const unsigned char *msg;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse new session ticket" ) );
+
+    if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
+        return( ret );
+    }
+
+    if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad new session ticket message" ) );
+        mbedtls_ssl_send_alert_message(
+            ssl,
+            MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+            MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
+        return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+    }
+
+    /*
+     * struct {
+     *     uint32 ticket_lifetime_hint;
+     *     opaque ticket<0..2^16-1>;
+     * } NewSessionTicket;
+     *
+     * 0  .  3   ticket_lifetime_hint
+     * 4  .  5   ticket_len (n)
+     * 6  .  5+n ticket content
+     */
+    if( ssl->in_msg[0] != MBEDTLS_SSL_HS_NEW_SESSION_TICKET ||
+        ssl->in_hslen < 6 + mbedtls_ssl_hs_hdr_len( ssl ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad new session ticket message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_NEW_SESSION_TICKET );
+    }
+
+    msg = ssl->in_msg + mbedtls_ssl_hs_hdr_len( ssl );
+
+    lifetime = ( ((uint32_t) msg[0]) << 24 ) | ( msg[1] << 16 ) |
+               ( msg[2] << 8 ) | ( msg[3] );
+
+    ticket_len = ( msg[4] << 8 ) | ( msg[5] );
+
+    if( ticket_len + 6 + mbedtls_ssl_hs_hdr_len( ssl ) != ssl->in_hslen )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad new session ticket message" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_NEW_SESSION_TICKET );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "ticket length: %" MBEDTLS_PRINTF_SIZET, ticket_len ) );
+
+    /* We're not waiting for a NewSessionTicket message any more */
+    ssl->handshake->new_session_ticket = 0;
+    ssl->state = MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC;
+
+    /*
+     * Zero-length ticket means the server changed his mind and doesn't want
+     * to send a ticket after all, so just forget it
+     */
+    if( ticket_len == 0 )
+        return( 0 );
+
+    if( ssl->session != NULL && ssl->session->ticket != NULL )
+    {
+        mbedtls_platform_zeroize( ssl->session->ticket,
+                                  ssl->session->ticket_len );
+        mbedtls_free( ssl->session->ticket );
+        ssl->session->ticket = NULL;
+        ssl->session->ticket_len = 0;
+    }
+
+    mbedtls_platform_zeroize( ssl->session_negotiate->ticket,
+                              ssl->session_negotiate->ticket_len );
+    mbedtls_free( ssl->session_negotiate->ticket );
+    ssl->session_negotiate->ticket = NULL;
+    ssl->session_negotiate->ticket_len = 0;
+
+    if( ( ticket = mbedtls_calloc( 1, ticket_len ) ) == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "ticket alloc failed" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                        MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR );
+        return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+    }
+
+    memcpy( ticket, msg + 6, ticket_len );
+
+    ssl->session_negotiate->ticket = ticket;
+    ssl->session_negotiate->ticket_len = ticket_len;
+    ssl->session_negotiate->ticket_lifetime = lifetime;
+
+    /*
+     * RFC 5077 section 3.4:
+     * "If the client receives a session ticket from the server, then it
+     * discards any Session ID that was sent in the ServerHello."
+     */
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "ticket in use, discarding session id" ) );
+    ssl->session_negotiate->id_len = 0;
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse new session ticket" ) );
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_SESSION_TICKETS */
+
+/*
+ * SSL handshake -- client side -- single step
+ */
+int mbedtls_ssl_handshake_client_step( mbedtls_ssl_context *ssl )
+{
+    int ret = 0;
+
+    if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER || ssl->handshake == NULL )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "client state: %d", ssl->state ) );
+
+    if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
+        return( ret );
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+        ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING )
+    {
+        if( ( ret = mbedtls_ssl_flight_transmit( ssl ) ) != 0 )
+            return( ret );
+    }
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+    /* Change state now, so that it is right in mbedtls_ssl_read_record(), used
+     * by DTLS for dropping out-of-sequence ChangeCipherSpec records */
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+    if( ssl->state == MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC &&
+        ssl->handshake->new_session_ticket != 0 )
+    {
+        ssl->state = MBEDTLS_SSL_SERVER_NEW_SESSION_TICKET;
+    }
+#endif
+
+    switch( ssl->state )
+    {
+        case MBEDTLS_SSL_HELLO_REQUEST:
+            ssl->state = MBEDTLS_SSL_CLIENT_HELLO;
+            break;
+
+       /*
+        *  ==>   ClientHello
+        */
+       case MBEDTLS_SSL_CLIENT_HELLO:
+           ret = ssl_write_client_hello( ssl );
+           break;
+
+       /*
+        *  <==   ServerHello
+        *        Certificate
+        *      ( ServerKeyExchange  )
+        *      ( CertificateRequest )
+        *        ServerHelloDone
+        */
+       case MBEDTLS_SSL_SERVER_HELLO:
+           ret = ssl_parse_server_hello( ssl );
+           break;
+
+       case MBEDTLS_SSL_SERVER_CERTIFICATE:
+           ret = mbedtls_ssl_parse_certificate( ssl );
+           break;
+
+       case MBEDTLS_SSL_SERVER_KEY_EXCHANGE:
+           ret = ssl_parse_server_key_exchange( ssl );
+           break;
+
+       case MBEDTLS_SSL_CERTIFICATE_REQUEST:
+           ret = ssl_parse_certificate_request( ssl );
+           break;
+
+       case MBEDTLS_SSL_SERVER_HELLO_DONE:
+           ret = ssl_parse_server_hello_done( ssl );
+           break;
+
+       /*
+        *  ==> ( Certificate/Alert  )
+        *        ClientKeyExchange
+        *      ( CertificateVerify  )
+        *        ChangeCipherSpec
+        *        Finished
+        */
+       case MBEDTLS_SSL_CLIENT_CERTIFICATE:
+           ret = mbedtls_ssl_write_certificate( ssl );
+           break;
+
+       case MBEDTLS_SSL_CLIENT_KEY_EXCHANGE:
+           ret = ssl_write_client_key_exchange( ssl );
+           break;
+
+       case MBEDTLS_SSL_CERTIFICATE_VERIFY:
+           ret = ssl_write_certificate_verify( ssl );
+           break;
+
+       case MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC:
+           ret = mbedtls_ssl_write_change_cipher_spec( ssl );
+           break;
+
+       case MBEDTLS_SSL_CLIENT_FINISHED:
+           ret = mbedtls_ssl_write_finished( ssl );
+           break;
+
+       /*
+        *  <==   ( NewSessionTicket )
+        *        ChangeCipherSpec
+        *        Finished
+        */
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+       case MBEDTLS_SSL_SERVER_NEW_SESSION_TICKET:
+           ret = ssl_parse_new_session_ticket( ssl );
+           break;
+#endif
+
+       case MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC:
+           ret = mbedtls_ssl_parse_change_cipher_spec( ssl );
+           break;
+
+       case MBEDTLS_SSL_SERVER_FINISHED:
+           ret = mbedtls_ssl_parse_finished( ssl );
+           break;
+
+       case MBEDTLS_SSL_FLUSH_BUFFERS:
+           MBEDTLS_SSL_DEBUG_MSG( 2, ( "handshake: done" ) );
+           ssl->state = MBEDTLS_SSL_HANDSHAKE_WRAPUP;
+           break;
+
+       case MBEDTLS_SSL_HANDSHAKE_WRAPUP:
+           mbedtls_ssl_handshake_wrapup( ssl );
+           break;
+
+       default:
+           MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid state %d", ssl->state ) );
+           return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+   }
+
+    return( ret );
+}
+#endif /* MBEDTLS_SSL_CLI_C */