Use libc if_nametoindex if available when parsing IPs

Fixes https://github.com/ziglang/zig/issues/10521 and makes a couple of
additional tests pass when linking libc.

5 files changed, 50 insertions, 19 deletions

diff --git a/lib/std/c.zig b/lib/std/c.zig
index 9203232e6b..ed9ceada00 100644
--- a/lib/std/c.zig
+++ b/lib/std/c.zig
@@ -357,6 +357,8 @@ pub extern "c" fn openlog(ident: [*:0]const u8, logopt: c_int, facility: c_int)
 pub extern "c" fn closelog() void;
 pub extern "c" fn setlogmask(maskpri: c_int) c_int;
 
+pub extern "c" fn if_nametoindex([*:0]const u8) c_int;
+
 pub const max_align_t = if (builtin.abi == .msvc)
     f64
 else if (builtin.target.isDarwin())
diff --git a/lib/std/c/darwin.zig b/lib/std/c/darwin.zig
index bfb805c36c..2a4541ea74 100644
--- a/lib/std/c/darwin.zig
+++ b/lib/std/c/darwin.zig
@@ -108,6 +108,8 @@ pub fn sigaddset(set: *sigset_t, signo: u5) void {
 
 pub extern "c" fn sigaltstack(ss: ?*stack_t, old_ss: ?*stack_t) c_int;
 
+pub const IFNAMESIZE = 16;
+
 pub const AI = struct {
     /// get address to use bind()
     pub const PASSIVE = 0x00000001;
diff --git a/lib/std/net.zig b/lib/std/net.zig
index 1165ac6073..78d59ae9c0 100644
--- a/lib/std/net.zig
+++ b/lib/std/net.zig
@@ -636,17 +636,35 @@ pub fn connectUnixSocket(path: []const u8) !Stream {
 }
 
 fn if_nametoindex(name: []const u8) !u32 {
-    var ifr: os.ifreq = undefined;
-    var sockfd = try os.socket(os.AF.UNIX, os.SOCK.DGRAM | os.SOCK.CLOEXEC, 0);
-    defer os.closeSocket(sockfd);
+    if (builtin.target.os.tag == .linux) {
+        var ifr: os.ifreq = undefined;
+        var sockfd = try os.socket(os.AF.UNIX, os.SOCK.DGRAM | os.SOCK.CLOEXEC, 0);
+        defer os.closeSocket(sockfd);
+
+        std.mem.copy(u8, &ifr.ifrn.name, name);
+        ifr.ifrn.name[name.len] = 0;
+
+        // TODO investigate if this needs to be integrated with evented I/O.
+        try os.ioctl_SIOCGIFINDEX(sockfd, &ifr);
 
-    std.mem.copy(u8, &ifr.ifrn.name, name);
-    ifr.ifrn.name[name.len] = 0;
+        return @bitCast(u32, ifr.ifru.ivalue);
+    }
+
+    if (builtin.link_libc) {
+        if (name.len >= os.IFNAMESIZE)
+            return error.NameTooLong;
 
-    // TODO investigate if this needs to be integrated with evented I/O.
-    try os.ioctl_SIOCGIFINDEX(sockfd, &ifr);
+        var if_name: [os.IFNAMESIZE:0]u8 = undefined;
+        std.mem.copy(u8, &if_name, name);
+        if_name[name.len] = 0;
+        const if_slice = if_name[0..name.len :0];
+        const index = os.system.if_nametoindex(if_slice);
+        if (index == 0)
+            return error.InterfaceNotFound;
+        return @bitCast(u32, index);
+    }
 
-    return @bitCast(u32, ifr.ifru.ivalue);
+    @compileError("std.net.if_nametoindex unimplemented for this OS");
 }
 
 pub const AddressList = struct {
diff --git a/lib/std/net/test.zig b/lib/std/net/test.zig
index f181bb49ea..0fa853151a 100644
--- a/lib/std/net/test.zig
+++ b/lib/std/net/test.zig
@@ -49,7 +49,7 @@ test "parse and render IPv6 addresses" {
     try testing.expectError(error.Incomplete, net.Address.parseIp6("FF01:", 0));
     try testing.expectError(error.InvalidIpv4Mapping, net.Address.parseIp6("::123.123.123.123", 0));
     // TODO Make this test pass on other operating systems.
-    if (builtin.os.tag == .linux) {
+    if (builtin.os.tag == .linux or builtin.link_libc) {
         try testing.expectError(error.Incomplete, net.Address.resolveIp6("ff01::fb%", 0));
         try testing.expectError(error.Overflow, net.Address.resolveIp6("ff01::fb%wlp3s0s0s0s0s0s0s0s0", 0));
         try testing.expectError(error.Overflow, net.Address.resolveIp6("ff01::fb%12345678901234", 0));
@@ -57,7 +57,7 @@ test "parse and render IPv6 addresses" {
 }
 
 test "invalid but parseable IPv6 scope ids" {
-    if (builtin.os.tag != .linux) {
+    if (builtin.os.tag != .linux or !builtin.link_libc) {
         // Currently, resolveIp6 with alphanumerical scope IDs only works on Linux.
         // TODO Make this test pass on other operating systems.
         return error.SkipZigTest;
diff --git a/lib/std/x/os/net.zig b/lib/std/x/os/net.zig
index c71bc5bd22..37a1d98137 100644
--- a/lib/std/x/os/net.zig
+++ b/lib/std/x/os/net.zig
@@ -16,28 +16,37 @@ pub fn resolveScopeId(name: []const u8) !u32 {
     if (have_ifnamesize) {
         if (name.len >= os.IFNAMESIZE) return error.NameTooLong;
 
-        if (native_os.tag == .windows) {
+        if (native_os.tag == .windows or builtin.link_libc) {
             var interface_name: [os.IFNAMESIZE:0]u8 = undefined;
             mem.copy(u8, &interface_name, name);
             interface_name[name.len] = 0;
 
-            const rc = os.windows.ws2_32.if_nametoindex(@ptrCast([*:0]const u8, &interface_name));
+            const rc = blk: {
+                if (native_os.tag == .windows) {
+                    break :blk os.windows.ws2_32.if_nametoindex(@ptrCast([*:0]const u8, &interface_name));
+                } else {
+                    const index = os.system.if_nametoindex(@ptrCast([*:0]const u8, &interface_name));
+                    break :blk @bitCast(u32, index);
+                }
+            };
             if (rc == 0) {
                 return error.InterfaceNotFound;
             }
             return rc;
         }
 
-        const fd = try os.socket(os.AF.INET, os.SOCK.DGRAM, 0);
-        defer os.closeSocket(fd);
+        if (native_os.tag == .linux) {
+            const fd = try os.socket(os.AF.INET, os.SOCK.DGRAM, 0);
+            defer os.closeSocket(fd);
 
-        var f: os.ifreq = undefined;
-        mem.copy(u8, &f.ifrn.name, name);
-        f.ifrn.name[name.len] = 0;
+            var f: os.ifreq = undefined;
+            mem.copy(u8, &f.ifrn.name, name);
+            f.ifrn.name[name.len] = 0;
 
-        try os.ioctl_SIOCGIFINDEX(fd, &f);
+            try os.ioctl_SIOCGIFINDEX(fd, &f);
 
-        return @bitCast(u32, f.ifru.ivalue);
+            return @bitCast(u32, f.ifru.ivalue);
+        }
     }
 
     return error.InterfaceNotFound;