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namespace fs = std::filesystem;
class ModDownloader
{
private:
const char* VERIFICATION_FLAG = "-disablemodverification";
const char* CUSTOM_MODS_URL_FLAG = "-customverifiedurl=";
const char* DEFAULT_MODS_LIST_URL = "https://raw.githubusercontent.com/R2Northstar/VerifiedMods/main/verified-mods.json";
char* modsListUrl;
enum class VerifiedModPlatform
{
Unknown,
Thunderstore
};
struct VerifiedModVersion
{
std::string checksum;
std::string downloadLink;
VerifiedModPlatform platform;
};
struct VerifiedModDetails
{
std::unordered_map<std::string, VerifiedModVersion> versions = {};
};
std::unordered_map<std::string, VerifiedModDetails> verifiedMods = {};
/**
* Mod archive download callback.
*
* This function is called by curl as it's downloading the mod archive; this
* will retrieve the current `ModDownloader` instance and update its `modState`
* member accordingly.
*/
static int ModFetchingProgressCallback(
void* ptr, curl_off_t totalDownloadSize, curl_off_t finishedDownloadSize, curl_off_t totalToUpload, curl_off_t nowUploaded);
/**
* Downloads a mod archive from distant store.
*
* This rebuilds the URI of the mod archive using both a predefined store URI
* and the mod dependency string from the `verifiedMods` variable, or using
* input mod name as mod dependency string if bypass flag is set up; fetched
* archive is then stored in a temporary location.
*
* If something went wrong during archive download, this will return an empty
* optional object.
*
* @param modName name of the mod to be downloaded
* @param modVersion version of the mod to be downloaded
* @returns location of the downloaded archive
*/
std::optional<fs::path> FetchModFromDistantStore(std::string_view modName, VerifiedModVersion modVersion);
/**
* Tells if a mod archive has not been corrupted.
*
* The mod validation procedure includes computing the SHA256 hash of the final
* archive, which is stored in the verified mods list. This hash is used by this
* very method to ensure the archive downloaded from the Internet is the exact
* same that has been manually verified.
*
* @param modPath path of the archive to check
* @param expectedChecksum checksum the archive should have
* @returns whether archive is legit
*/
bool IsModLegit(fs::path modPath, std::string_view expectedChecksum);
/**
* Extracts a mod archive to the game folder.
*
* This extracts a downloaded mod archive from its original location to the
* current game profile; the install folder is defined by the platform parameter.
*
* @param modPath location of the downloaded archive
* @param platform origin of the downloaded archive
* @returns nothing
*/
void ExtractMod(fs::path modPath, VerifiedModPlatform platform);
public:
ModDownloader();
/**
* Retrieves the verified mods list from the central authority.
*
* The Northstar auto-downloading feature does NOT allow automatically installing
* all mods for various (notably security) reasons; mods that are candidate to
* auto-downloading are rather listed on a GitHub repository
* (https://raw.githubusercontent.com/R2Northstar/VerifiedMods/main/verified-mods.json),
* which this method gets via a HTTP call to load into local state.
*
* If list fetching fails, local mods list will be initialized as empty, thus
* preventing any mod from being auto-downloaded.
*
* @returns nothing
*/
void FetchModsListFromAPI();
/**
* Checks whether a mod is verified.
*
* A mod is deemed verified/authorized through a manual validation process that is
* described here: https://github.com/R2Northstar/VerifiedMods; in practice, a mod
* is considered authorized if their name AND exact version appear in the
* `verifiedMods` variable.
*
* @param modName name of the mod to be checked
* @param modVersion version of the mod to be checked, must follow semantic versioning
* @returns whether the mod is authorized and can be auto-downloaded
*/
bool IsModAuthorized(std::string_view modName, std::string_view modVersion);
/**
* Downloads a given mod from Thunderstore API to local game profile.
*
* @param modName name of the mod to be downloaded
* @param modVersion version of the mod to be downloaded
* @returns nothing
**/
void DownloadMod(std::string modName, std::string modVersion);
enum ModInstallState
{
MANIFESTO_FETCHING,
// Normal installation process
DOWNLOADING,
CHECKSUMING,
EXTRACTING,
DONE, // Everything went great, mod can be used in-game
ABORTED, // User cancelled mod install process
// Errors
FAILED, // Generic error message, should be avoided as much as possible
FAILED_READING_ARCHIVE,
FAILED_WRITING_TO_DISK,
MOD_FETCHING_FAILED,
MOD_CORRUPTED, // Downloaded archive checksum does not match verified hash
NO_DISK_SPACE_AVAILABLE,
NOT_FOUND, // Mod is not currently being auto-downloaded
UNKNOWN_PLATFORM
};
struct MOD_STATE
{
ModInstallState state;
int progress;
int total;
float ratio;
} modState = {};
/**
* Cancels installation of the mod.
*
* Prevents installation of the mod currently being installed, no matter the install
* progress (downloading, checksuming, extracting), and frees all resources currently
* being used in this purpose.
*
* @returns nothing
*/
void CancelDownload();
};
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