/// <summary>
/// Default constructor.
/// </summary>
/// <param name="uri">The STUN or TURN server URI the connection is being attempted to.</param>
/// <param name="id">Needs to be set uniquely for each ICE server used in this session. Gets added to the
/// transaction ID to facilitate quick matching of STUN requests and responses. Needs to be between
/// 0 and 9.</param>
/// <param name="username">Optional. If authentication is required the username to use.</param>
/// <param name="password">Optional. If authentication is required the password to use.</param>
internal IceServer(STUNUri uri, int id, string username, string password)
{
_uri = uri;
_id = id;
_username = username;
_password = password;
GenerateNewTransactionID();
}
/// <summary>
/// Resolve method that can be used to request an AAAA result and fallback to a A
/// lookup if none found.
/// </summary>
/// <param name="uri">The URI to lookup.</param>
/// <param name="preferIPv6">True if IPv6 (AAAA record lookup) is preferred.</param>
/// <returns>An IPEndPoint or null.</returns>
public static Task <IPEndPoint> Resolve(STUNUri uri, bool preferIPv6 = false)
{
if (preferIPv6)
{
// Try AAAA record lookup followed by A record if none found.
return(Resolve(uri, QueryType.AAAA)
.ContinueWith(x => x.Result ?? Resolve(uri, QueryType.A).Result));
}
else
{
return(Resolve(uri, QueryType.A));
}
}
public static bool TryParse(string uriStr, out STUNUri uri)
{
try
{
uri = ParseSTUNUri(uriStr);
return(uri != null);
}
catch
{
uri = null;
return(false);
}
}
/// <summary>
/// Resolve method that performs either an A or AAAA record lookup. If required
/// a SRV record lookup will be performed prior to the A or AAAA lookup.
/// </summary>
/// <param name="uri">The STUN uri to lookup.</param>
/// <param name="queryType">Whether the address lookup should be A or AAAA.</param>
/// <returns>An IPEndPoint or null.</returns>
private static async Task <IPEndPoint> Resolve(STUNUri uri, QueryType queryType)
{
if (uri == null || String.IsNullOrWhiteSpace(uri.Host))
{
throw new ArgumentNullException("uri", "DNS resolve was supplied an empty input.");
}
if (IPAddress.TryParse(uri.Host, out var ipAddress))
{
// Target is already an IP address, no DNS lookup required.
return(new IPEndPoint(ipAddress, uri.Port));
}
else
{
if (!uri.Host.Contains(".") || uri.Host.EndsWith(MDNS_TLD))
{
AddressFamily family = (queryType == QueryType.AAAA) ? AddressFamily.InterNetworkV6 :
AddressFamily.InterNetwork;
// The lookup is for a local network host. Use the OS DNS logic as the
// main DNS client can be configured to use external DNS servers that won't
// be able to lookup this hostname.
IPHostEntry hostEntry = null;
try
{
hostEntry = Dns.GetHostEntry(uri.Host);
}
catch (SocketException)
{
// Socket exception gets thrown for failed lookups,
}
if (hostEntry != null)
{
var addressList = hostEntry.AddressList;
if (addressList?.Length == 0)
{
logger.LogWarning($"Operating System DNS lookup failed for {uri.Host}.");
return(null);
}
else
{
if (addressList.Any(x => x.AddressFamily == family))
{
var addressResult = addressList.First(x => x.AddressFamily == family);
return(new IPEndPoint(addressResult, uri.Port));
}
else
{
// Didn't get a result for the preferred address family so just use the
// first available result.
var addressResult = addressList.First();
return(new IPEndPoint(addressResult, uri.Port));
}
}
}
else
{
return(null);
}
}
else
{
if (uri.ExplicitPort)
{
return(HostQuery(uri.Host, uri.Port, queryType));
}
else
{
try
{
ServiceHostEntry srvResult = null;
// No explicit port so use a SRV -> (A | AAAA -> A) record lookup.
var result = await _lookupClient.ResolveServiceAsync(uri.Host, uri.Scheme.ToString(), uri.Protocol.ToString().ToLower()).ConfigureAwait(false);
if (result == null || result.Count() == 0)
{
logger.LogDebug($"STUNDns SRV lookup returned no results for {uri}.");
}
else
{
srvResult = result.OrderBy(y => y.Priority).ThenByDescending(w => w.Weight).FirstOrDefault();
}
string host = uri.Host; // If no SRV results then fallback is to lookup the hostname directly.
int port = uri.Port; // If no SRV results then fallback is to use the default port.
if (srvResult != null)
{
host = srvResult.HostName;
port = srvResult.Port;
}
return(HostQuery(host, port, queryType));
}
catch (Exception e)
{
logger.LogDebug($"STUNDns SRV lookup failure for {uri}. {e?.InnerException?.Message}");
return(null);
}
}
}
}
}
/// <summary>
/// Resolve method that can be used to request an AAAA result and fallback to a A
/// lookup if none found.
/// </summary>
/// <param name="uri">The URI to lookup.</param>
/// <param name="preferIPv6">True if IPv6 (AAAA record lookup) is preferred.</param>
/// <returns>An IPEndPoint or null.</returns>
public static Task <IPEndPoint> Resolve(STUNUri uri, bool preferIPv6 = false)
{
return(Resolve(uri, preferIPv6 ? QueryType.AAAA : QueryType.A));
}
/// <summary>
/// Resolve method that performs either an A or AAAA record lookup. If required
/// a SRV record lookup will be performed prior to the A or AAAA lookup.
/// </summary>
/// <param name="uri">The STUN uri to lookup.</param>
/// <param name="queryType">Whether the address lookup should be A or AAAA.</param>
/// <returns>An IPEndPoint or null.</returns>
public static Task <IPEndPoint> Resolve(STUNUri uri, QueryType queryType)
{
if (uri == null || String.IsNullOrWhiteSpace(uri.Host))
{
throw new ArgumentNullException("uri", "DNS resolve was supplied an empty input.");
}
if (IPAddress.TryParse(uri.Host, out var ipAddress))
{
// Target is already an IP address, no DNS lookup required.
return(Task.FromResult(new IPEndPoint(ipAddress, uri.Port)));
}
else
{
if (!uri.Host.Contains(".") || uri.Host.EndsWith(MDNS_TLD))
{
AddressFamily family = (queryType == QueryType.AAAA) ? AddressFamily.InterNetworkV6 :
AddressFamily.InterNetwork;
// The lookup is for a local network host. Use the OS DNS logic as the
// main DNS client can be configured to use external DNS servers that won't
// be able to lookup this hostname.
IPHostEntry hostEntry = null;
try
{
hostEntry = Dns.GetHostEntry(uri.Host);
}
catch (SocketException)
{
// Socket exception gets thrown for failed lookups,
}
if (hostEntry != null)
{
var addressList = hostEntry.AddressList;
if (addressList?.Length == 0)
{
logger.LogWarning($"Operating System DNS lookup failed for {uri.Host}.");
return(Task.FromResult <IPEndPoint>(null));
}
else
{
if (addressList.Any(x => x.AddressFamily == family))
{
var addressResult = addressList.First(x => x.AddressFamily == family);
return(Task.FromResult(new IPEndPoint(addressResult, uri.Port)));
}
else
{
return(Task.FromResult <IPEndPoint>(null));
}
}
}
else
{
return(Task.FromResult <IPEndPoint>(null));
}
}
else
{
if (uri.ExplicitPort)
{
// If the URI has an explicit port then it indicates SRV records should not be used.
return(_lookupClient.QueryAsync(uri.Host, queryType)
.ContinueWith <IPEndPoint>(x =>
{
var addrRecord = x.Result.Answers.FirstOrDefault();
return GetFromLookupResult(addrRecord, uri.Port);
}));
}
else
{
// No explicit port so use a SRV -> (A | AAAA) record lookup.
return(_lookupClient.ResolveServiceAsync(uri.Host, uri.Scheme.ToString(), uri.Protocol)
.ContinueWith <IPEndPoint>(x =>
{
var srvResult = x.Result.OrderBy(y => y.Priority).ThenByDescending(w => w.Weight).FirstOrDefault();
string host = uri.Host; // If no SRV results then fallback is to lookup the hostname directly.
int port = uri.Port; // If no SRV results then fallback is to use the default port.
if (srvResult != null)
{
host = srvResult.HostName;
port = srvResult.Port;
}
var addrRecord = _lookupClient.Query(host, queryType).Answers.FirstOrDefault();
return GetFromLookupResult(addrRecord, uri.Port);
}));
}
}
}
}
public static bool AreEqual(STUNUri uri1, STUNUri uri2)
{
return(uri1 == uri2);
}
public static STUNUri ParseSTUNUri(string uri)
{
STUNUri stunUri = new STUNUri();
if (String.IsNullOrEmpty(uri))
{
throw new ApplicationException("A STUN URI cannot be parsed from an empty string.");
}
else
{
uri = uri.Trim();
// If the scheme is included it needs to be within the first 5 characters.
if (uri.Length > SCHEME_MAX_LENGTH + 2)
{
string schemeStr = uri.Substring(0, SCHEME_MAX_LENGTH + 1);
int colonPosn = schemeStr.IndexOf(SCHEME_ADDR_SEPARATOR);
if (colonPosn == -1)
{
// No scheme has been specified, use default.
stunUri.Scheme = DefaultSTUNScheme;
}
else
{
if (!Enum.TryParse <STUNSchemesEnum>(schemeStr.Substring(0, colonPosn), true,
out stunUri.Scheme))
{
stunUri.Scheme = DefaultSTUNScheme;
}
uri = uri.Substring(colonPosn + 1);
}
}
if (uri.IndexOf(':') != -1)
{
stunUri.ExplicitPort = true;
if (IPSocket.TryParseIPEndPoint(uri, out var ipEndPoint))
{
if (ipEndPoint.AddressFamily == AddressFamily.InterNetworkV6)
{
stunUri.Host = $"[{ipEndPoint.Address}]";
}
else
{
stunUri.Host = ipEndPoint.Address.ToString();
}
stunUri.Port = ipEndPoint.Port;
}
else
{
stunUri.Host = uri.Substring(0, uri.LastIndexOf(':'));
if (!Int32.TryParse(uri.Substring(uri.LastIndexOf(':') + 1), out stunUri.Port))
{
stunUri.Port = STUNConstants.GetPortForScheme(stunUri.Scheme);
}
}
}
else
{
stunUri.Host = uri?.Trim();
stunUri.Port = STUNConstants.GetPortForScheme(stunUri.Scheme);
}
}
return(stunUri);
}