Retrieves the server's authentication string (SteamID).
Note: If called before server is connected to Steam, auth id will be invalid ([I:0:1], 1, etc.)
void GetServerAuthId(AuthIdType authType, char auth, int maxlen)
Auth id type and format to use. (Only AuthId_Steam3 and AuthId_SteamID64 are supported)
Buffer to store the server's auth id.
Maximum length of string buffer (includes NULL terminator).
Invalid AuthIdType given.