/// <summary>
/// Gets an ICE candidate for this ICE server once the required server responses have been received.
/// Note the related address and port are deliberately not set to avoid leaking information about
/// internal network configuration.
/// </summary>
/// <param name="init">The initialisation parameters for the ICE candidate (mainly local username).</param>
/// <param name="type">The type of ICE candidate to get, must be srflx or relay.</param>
/// <returns>An ICE candidate that can be sent to the remote peer.</returns>
internal RTCIceCandidate GetCandidate(RTCIceCandidateInit init, RTCIceCandidateType type)
{
RTCIceCandidate candidate = new RTCIceCandidate(init);
if (type == RTCIceCandidateType.srflx && ServerReflexiveEndPoint != null)
{
candidate.SetAddressProperties(RTCIceProtocol.udp, ServerReflexiveEndPoint.Address,
(ushort)ServerReflexiveEndPoint.Port,
type, null, 0);
candidate.IceServer = this;
return(candidate);
}
else if (type == RTCIceCandidateType.relay && RelayEndPoint != null)
{
candidate.SetAddressProperties(RTCIceProtocol.udp, RelayEndPoint.Address, (ushort)RelayEndPoint.Port,
type, null, 0);
candidate.IceServer = this;
return(candidate);
}
else
{
logger.LogWarning($"Could not get ICE server candidate for {_uri} and type {type}.");
return(null);
}
}
/// <summary>
/// Acquires an ICE candidate for each IP address that this host has except for:
/// - Loopback addresses must not be included.
/// - Deprecated IPv4-compatible IPv6 addresses and IPv6 site-local unicast addresses
/// must not be included,
/// - IPv4-mapped IPv6 address should not be included.
/// - If a non-location tracking IPv6 address is available use it and do not included
/// location tracking enabled IPv6 addresses (i.e. prefer temporary IPv6 addresses over
/// permanent addresses), see RFC6724.
/// </summary>
/// <remarks>See https://tools.ietf.org/html/rfc8445#section-5.1.1.1</remarks>
/// <returns>A list of "host" ICE candidates for the local machine.</returns>
private List <RTCIceCandidate> GetHostCandidates()
{
List <RTCIceCandidate> hostCandidates = new List <RTCIceCandidate>();
RTCIceCandidateInit init = new RTCIceCandidateInit {
usernameFragment = LocalIceUser
};
var rtpBindAddress = _rtpChannel.RTPLocalEndPoint.Address;
// We get a list of local addresses that can be used with the address the RTP socket is bound on.
List <IPAddress> localAddresses = null;
if (IPAddress.IPv6Any.Equals(rtpBindAddress))
{
if (_rtpChannel.RtpSocket.DualMode)
{
// IPv6 dual mode listening on [::] means we can use all valid local addresses.
localAddresses = NetServices.LocalIPAddresses.Where(x =>
!IPAddress.IsLoopback(x) && !x.IsIPv4MappedToIPv6 && !x.IsIPv6SiteLocal).ToList();
}
else
{
// IPv6 but not dual mode on [::] means can use all valid local IPv6 addresses.
localAddresses = NetServices.LocalIPAddresses.Where(x => x.AddressFamily == AddressFamily.InterNetworkV6 &&
!IPAddress.IsLoopback(x) && !x.IsIPv4MappedToIPv6 && !x.IsIPv6SiteLocal).ToList();
}
}
else if (IPAddress.Any.Equals(rtpBindAddress))
{
// IPv4 on 0.0.0.0 means can use all valid local IPv4 addresses.
localAddresses = NetServices.LocalIPAddresses.Where(x => x.AddressFamily == AddressFamily.InterNetwork &&
!IPAddress.IsLoopback(x)).ToList();
}
else
{
// If not bound on a [::] or 0.0.0.0 means we're only listening on a specific IP address
// and that's the only one that can be used for the host candidate.
localAddresses = new List <IPAddress> {
rtpBindAddress
};
}
foreach (var localAddress in localAddresses)
{
var hostCandidate = new RTCIceCandidate(init);
hostCandidate.SetAddressProperties(RTCIceProtocol.udp, localAddress, (ushort)_rtpChannel.RTPPort, RTCIceCandidateType.host, null, 0);
// We currently only support a single multiplexed connection for all data streams and RTCP.
if (hostCandidate.component == RTCIceComponent.rtp && hostCandidate.sdpMLineIndex == 0)
{
hostCandidates.Add(hostCandidate);
OnIceCandidate?.Invoke(hostCandidate);
}
}
return(hostCandidates);
}
/// <summary>
/// Creates a new entry for the ICE session checklist.
/// </summary>
/// <param name="localCandidate">The local candidate for the checklist pair.</param>
/// <param name="remoteCandidate">The remote candidate for the checklist pair.</param>
/// <param name="isLocalController">True if we are acting as the controlling agent in the ICE session.</param>
public ChecklistEntry(RTCIceCandidate localCandidate, RTCIceCandidate remoteCandidate, bool isLocalController)
{
LocalCandidate = localCandidate;
RemoteCandidate = remoteCandidate;
IsLocalController = isLocalController;
LocalPriority = localCandidate.priority;
RemotePriority = remoteCandidate.priority;
}
/// <summary>
/// Creates a new entry for the ICE session checklist.
/// </summary>
/// <param name="localCandidate">The local candidate for the checklist pair.</param>
/// <param name="remoteCandidate">The remote candidate for the checklist pair.</param>
/// <param name="isLocalController">True if we are acting as the controlling agent in the ICE session.</param>
public ChecklistEntry(RTCIceCandidate localCandidate, RTCIceCandidate remoteCandidate, bool isLocalController)
{
LocalCandidate = localCandidate;
RemoteCandidate = remoteCandidate;
var controllingCandidate = (isLocalController) ? localCandidate : remoteCandidate;
var controlledCandidate = (isLocalController) ? remoteCandidate : localCandidate;
Priority = (2 << 32) * Math.Min(controllingCandidate.priority, controlledCandidate.priority) +
(ulong)2 * Math.Max(controllingCandidate.priority, controlledCandidate.priority) +
(ulong)((controllingCandidate.priority > controlledCandidate.priority) ? 1 : 0);
}
public static RTCIceCandidate Parse(string candidateLine)
{
if (string.IsNullOrEmpty(candidateLine))
{
throw new ArgumentNullException("Cant parse ICE candidate from empty string.", candidateLine);
}
else
{
candidateLine = candidateLine.Replace("candidate:", "");
RTCIceCandidate candidate = new RTCIceCandidate();
string[] candidateFields = candidateLine.Trim().Split(' ');
candidate.foundation = candidateFields[0];
if (Enum.TryParse <RTCIceComponent>(candidateFields[1], out var candidateComponent))
{
candidate.component = candidateComponent;
}
if (Enum.TryParse <RTCIceProtocol>(candidateFields[2], out var candidateProtocol))
{
candidate.protocol = candidateProtocol;
}
if (ulong.TryParse(candidateFields[3], out var candidatePriority))
{
candidate.priority = candidatePriority;
}
candidate.address = candidateFields[4];
candidate.port = Convert.ToUInt16(candidateFields[5]);
if (Enum.TryParse <RTCIceCandidateType>(candidateFields[7], out var candidateType))
{
candidate.type = candidateType;
}
if (candidateFields.Length > 8 && candidateFields[8] == REMOTE_ADDRESS_KEY)
{
candidate.relatedAddress = candidateFields[9];
}
if (candidateFields.Length > 10 && candidateFields[10] == REMOTE_PORT_KEY)
{
candidate.relatedPort = Convert.ToUInt16(candidateFields[11]);
}
return(candidate);
}
}
/// <summary>
/// Adds a remote ICE candidate to the list this peer is attempting to connect against.
/// </summary>
/// <param name="candidateInit">The remote candidate to add.</param>
public void addIceCandidate(RTCIceCandidateInit candidateInit)
{
RTCIceCandidate candidate = new RTCIceCandidate(candidateInit);
if (_rtpIceChannel.Component == candidate.component)
{
_rtpIceChannel.AddRemoteCandidate(candidate);
}
else
{
logger.LogWarning($"Remote ICE candidate not added as no available ICE session for component {candidate.component}.");
}
}
/// <summary>
/// Updates the checklist with new candidate pairs.
/// </summary>
/// <remarks>
/// From https://tools.ietf.org/html/rfc8445#section-6.1.2.2:
/// IPv6 link-local addresses MUST NOT be paired with other than link-local addresses.
/// </remarks>
private void UpdateChecklist(RTCIceCandidate remoteCandidate)
{
lock (_checklist)
{
// Local server reflexive candidates don't get added to the checklist since they are just local
// "host" candidates with an extra NAT address mapping. The NAT address mapping is needed for the
// remote ICE peer but locally a server reflexive candidate is always going to be represented by
// a "host" candidate.
foreach (var localCandidate in Candidates.Where(x => x.type != RTCIceCandidateType.srflx))
{
if (localCandidate.CandidateAddress != null && remoteCandidate.CandidateAddress != null &&
localCandidate.CandidateAddress.AddressFamily == remoteCandidate.CandidateAddress.AddressFamily)
{
if (remoteCandidate.CandidateAddress.IsIPv6LinkLocal)
{
if (localCandidate.CandidateAddress.IsIPv6LinkLocal)
{
// Only pair IPv6 link local candidates if both are link local.
ChecklistEntry entry = new ChecklistEntry(localCandidate, remoteCandidate, IsController);
// Because only ONE checklist is currently supported each candidate pair can be set to
// a "waiting" state. If an additional checklist is ever added then only one candidate
// pair with the same foundation should be set to waiting across all checklists.
// See https://tools.ietf.org/html/rfc8445#section-6.1.2.6 for a somewhat convoluted
// explanation and example.
entry.State = ChecklistEntryState.Waiting;
_checklist.Add(entry);
}
}
else
{
ChecklistEntry entry = new ChecklistEntry(localCandidate, remoteCandidate, IsController);
// See comment above about why the candidate state is adjusted.
entry.State = ChecklistEntryState.Waiting;
_checklist.Add(entry);
}
}
}
// Finally sort the checklist to put it in priority order and if necessary remove lower
// priority pairs.
_checklist.Sort();
while (_checklist.Count > MAX_CHECKLIST_ENTRIES)
{
_checklist.RemoveAt(_checklist.Count - 1);
}
}
}
/// <summary>
/// Adds a remote ICE candidate to the ICE session.
/// </summary>
/// <param name="candidate">An ICE candidate from the remote party.</param>
public void AddRemoteCandidate(RTCIceCandidate candidate)
{
if (!_remoteCandidates.Any(x => x.foundation == candidate.foundation))
{
_remoteCandidates.Add(candidate);
UpdateChecklist(candidate);
}
else
{
// This occurs if the remote party made an offer and assumed we couldn't multiplex the audio and video streams.
// It will offer the same ICE candidates separately for the audio and video announcements.
logger.LogWarning($"ICE session not adding remote ICE candidate as candidate with foundation {candidate.foundation} already present.");
}
}
/// <summary>
/// Adds a remote ICE candidate to the ICE session.
/// </summary>
/// <param name="candidate">An ICE candidate from the remote party.</param>
public void AddRemoteCandidate(RTCIceCandidate candidate)
{
if (!_remoteCandidates.Any(x => x.foundation == candidate.foundation))
{
// Have a remote candidate. Connectivity checks can start. Note because we support ICE trickle
// we may also still be gathering candidates. Connectivity checks and gathering can be done in parallel.
_remoteCandidates.Add(candidate);
UpdateChecklist(candidate);
}
else
{
// This occurs if the remote party made an offer and assumed we couldn't multiplex the audio and video streams.
// It will offer the same ICE candidates separately for the audio and video announcements.
logger.LogWarning($"ICE session not adding remote ICE candidate as candidate with foundation {candidate.foundation} already present.");
}
}
/// <summary>
/// Adds a remote ICE candidate to the ICE session.
/// </summary>
/// <param name="candidate">An ICE candidate from the remote party.</param>
public void AddRemoteCandidate(RTCIceCandidate candidate)
{
if (candidate.component == Component)
{
// Have a remote candidate. Connectivity checks can start. Note because we support ICE trickle
// we may also still be gathering candidates. Connectivity checks and gathering can be done in parallel.
logger.LogDebug($"ICE session adding remote candidate: {candidate.ToString()}");
_remoteCandidates.Add(candidate);
UpdateChecklist(candidate);
}
else
{
// This occurs if the remote party made an offer and assumed we couldn't multiplex the audio and video streams.
// It will offer the same ICE candidates separately for the audio and video announcements.
logger.LogWarning($"ICE session omitting remote candidate with unsupported component: {candidate.ToString()}");
}
}
/// <summary>
/// Acquires an ICE candidate for each IP address that this host has except for:
/// - Loopback addresses must not be included.
/// - Deprecated IPv4-compatible IPv6 addresses and IPv6 site-local unicast addresses
/// must not be included,
/// - IPv4-mapped IPv6 address should not be included.
/// - If a non-location tracking IPv6 address is available use it and do not included
/// location tracking enabled IPv6 addresses (i.e. prefer temporary IPv6 addresses over
/// permanent addresses), see RFC6724.
/// </summary>
/// <remarks>See https://tools.ietf.org/html/rfc8445#section-5.1.1.1</remarks>
/// <returns>A list of "host" ICE candidates for the local machine.</returns>
private List <RTCIceCandidate> GetHostCandidates()
{
List <RTCIceCandidate> hostCandidates = new List <RTCIceCandidate>();
RTCIceCandidateInit init = new RTCIceCandidateInit {
usernameFragment = LocalIceUser
};
foreach (var localAddress in NetServices.LocalIPAddresses.Where(x =>
!IPAddress.IsLoopback(x) && !x.IsIPv4MappedToIPv6 && !x.IsIPv6SiteLocal))
{
var hostCandidate = new RTCIceCandidate(init);
hostCandidate.SetAddressProperties(RTCIceProtocol.udp, localAddress, (ushort)_rtpChannel.RTPPort, RTCIceCandidateType.host, null, 0);
// We currently only support a single multiplexed connection for all data streams and RTCP.
if (hostCandidate.component == RTCIceComponent.rtp && hostCandidate.sdpMLineIndex == 0)
{
hostCandidates.Add(hostCandidate);
}
}
return(hostCandidates);
}
/// <summary>
/// Updates the checklist with new candidate pairs.
/// </summary>
/// <remarks>
/// From https://tools.ietf.org/html/rfc8445#section-6.1.2.2:
/// IPv6 link-local addresses MUST NOT be paired with other than link-local addresses.
/// </remarks>
private void UpdateChecklist(RTCIceCandidate remoteCandidate)
{
lock (_checklist)
{
// TODO: Check for duplicate entries and adjust reflexive local candidates to use the base address
// as per https://tools.ietf.org/html/rfc8445#section-6.1.2.4.
foreach (var localCandidate in Candidates)
{
if (localCandidate.CandidateAddress != null && remoteCandidate.CandidateAddress != null &&
localCandidate.CandidateAddress.AddressFamily == remoteCandidate.CandidateAddress.AddressFamily)
{
if (remoteCandidate.CandidateAddress.IsIPv6LinkLocal)
{
if (localCandidate.CandidateAddress.IsIPv6LinkLocal)
{
// Only pair IPv6 link local candidates if both are link local.
ChecklistEntry entry = new ChecklistEntry(localCandidate, remoteCandidate, IsController);
_checklist.Add(entry);
_checklist.Sort();
}
}
else
{
ChecklistEntry entry = new ChecklistEntry(localCandidate, remoteCandidate, IsController);
_checklist.Add(entry);
_checklist.Sort();
}
}
}
while (_checklist.Count > MAX_CHECKLIST_ENTRIES)
{
_checklist.RemoveAt(_checklist.Count - 1);
}
}
}
/// <summary>
/// Updates the checklist with new candidate pairs.
/// </summary>
/// <remarks>
/// From https://tools.ietf.org/html/rfc8445#section-6.1.2.2:
/// IPv6 link-local addresses MUST NOT be paired with other than link-local addresses.
/// </remarks>
private void UpdateChecklist(RTCIceCandidate remoteCandidate)
{
lock (_checklist)
{
// Local server reflexive candidates don't get added to the checklist since they are just local
// "host" candidates with an extra NAT address mapping. The NAT address mapping is needed for the
// remote ICE peer but locally a server reflexive candidate is always going to be represented by
// a "host" candidate.
bool supportsIPv4 = _rtpChannel.RtpSocket.AddressFamily == AddressFamily.InterNetwork || _rtpChannel.IsDualMode;
bool supportsIPv6 = _rtpChannel.RtpSocket.AddressFamily == AddressFamily.InterNetworkV6 || _rtpChannel.IsDualMode;
if (remoteCandidate.addressFamily == AddressFamily.InterNetwork && supportsIPv4 ||
remoteCandidate.addressFamily == AddressFamily.InterNetworkV6 && supportsIPv6)
{
ChecklistEntry entry = new ChecklistEntry(_localChecklistCandidate, remoteCandidate, IsController);
// Because only ONE checklist is currently supported each candidate pair can be set to
// a "waiting" state. If an additional checklist is ever added then only one candidate
// pair with the same foundation should be set to waiting across all checklists.
// See https://tools.ietf.org/html/rfc8445#section-6.1.2.6 for a somewhat convoluted
// explanation and example.
entry.State = ChecklistEntryState.Waiting;
AddChecklistEntry(entry);
}
// Finally sort the checklist to put it in priority order and if necessary remove lower
// priority pairs.
_checklist.Sort();
while (_checklist.Count > MAX_CHECKLIST_ENTRIES)
{
_checklist.RemoveAt(_checklist.Count - 1);
}
}
}
/// <summary>
/// Creates a new instance of an ICE session.
/// </summary>
/// <param name="rtpChannel">The RTP channel is the object managing the socket
/// doing the media sending and receiving. Its the same socket the ICE session
/// will need to initiate all the connectivity checks on.</param>
/// <param name="component">The component (RTP or RTCP) the channel is being used for. Note
/// for cases where RTP and RTCP are multiplexed the component is set to RTP.</param>
public IceSession(RTPChannel rtpChannel, RTCIceComponent component)
{
if (rtpChannel == null)
{
throw new ArgumentNullException("rtpChannel");
}
_rtpChannel = rtpChannel;
Component = component;
LocalIceUser = Crypto.GetRandomString(ICE_UFRAG_LENGTH);
LocalIcePassword = Crypto.GetRandomString(ICE_PASSWORD_LENGTH);
_localChecklistCandidate = new RTCIceCandidate(new RTCIceCandidateInit {
sdpMid = "0", sdpMLineIndex = 0, usernameFragment = LocalIceUser
});
_localChecklistCandidate.SetAddressProperties(
RTCIceProtocol.udp,
_rtpChannel.RTPLocalEndPoint.Address,
(ushort)_rtpChannel.RTPLocalEndPoint.Port,
RTCIceCandidateType.host,
null,
0);
}
/// <summary>
/// Attempts to get a list of local ICE candidates.
/// </summary>
//private async Task GetIceCandidatesAsync()
//{
// // The media is being multiplexed so the audio and video RTP channel is the same.
// var rtpChannel = GetRtpChannel(SDPMediaTypesEnum.audio);
// if (rtpChannel == null)
// {
// throw new ApplicationException("Cannot start gathering ICE candidates without an RTP channel.");
// }
// else
// {
// var localIPAddresses = _offerAddresses ?? NetServices.GetAllLocalIPAddresses();
// IceNegotiationStartedAt = DateTime.Now;
// LocalIceCandidates = new List<IceCandidate>();
// foreach (var address in localIPAddresses.Where(x => x.AddressFamily == rtpChannel.RTPLocalEndPoint.AddressFamily))
// {
// var iceCandidate = new IceCandidate(address, (ushort)rtpChannel.RTPPort);
// if (_turnServerEndPoint != null)
// {
// iceCandidate.TurnServer = new TurnServer() { ServerEndPoint = _turnServerEndPoint };
// iceCandidate.InitialStunBindingCheck = SendTurnServerBindingRequest(iceCandidate);
// }
// LocalIceCandidates.Add(iceCandidate);
// }
// await Task.WhenAll(LocalIceCandidates.Where(x => x.InitialStunBindingCheck != null).Select(x => x.InitialStunBindingCheck)).ConfigureAwait(false);
// }
//}
public void ProcessStunMessage(STUNv2Message stunMessage, IPEndPoint receivedOn)
{
IPEndPoint remoteEndPoint = (!receivedOn.Address.IsIPv4MappedToIPv6) ? receivedOn : new IPEndPoint(receivedOn.Address.MapToIPv4(), receivedOn.Port);
//logger.LogDebug($"STUN message received from remote {remoteEndPoint} {stunMessage.Header.MessageType}.");
if (stunMessage.Header.MessageType == STUNv2MessageTypesEnum.BindingRequest)
{
STUNv2Message stunResponse = new STUNv2Message(STUNv2MessageTypesEnum.BindingSuccessResponse);
stunResponse.Header.TransactionId = stunMessage.Header.TransactionId;
stunResponse.AddXORMappedAddressAttribute(remoteEndPoint.Address, remoteEndPoint.Port);
// ToDo: Check authentication.
string localIcePassword = LocalIcePassword;
byte[] stunRespBytes = stunResponse.ToByteBufferStringKey(localIcePassword, true);
//iceCandidate.LocalRtpSocket.SendTo(stunRespBytes, remoteEndPoint);
_rtpChannel.SendAsync(RTPChannelSocketsEnum.RTP, remoteEndPoint, stunRespBytes);
//iceCandidate.LastStunRequestReceivedAt = DateTime.Now;
//iceCandidate.IsStunRemoteExchangeComplete = true;
//if (remoteEndPoint == null)
//{
//RemoteEndPoint = remoteEndPoint;
//SetDestination(SDPMediaTypesEnum.audio, RemoteEndPoint, RemoteEndPoint);
//OnIceConnected?.Invoke(iceCandidate, remoteEndPoint);
//IceConnectionState = RTCIceConnectionState.connected;
//}
if (_remoteCandidates != null && !_remoteCandidates.Any(x =>
(x.address == remoteEndPoint.Address.ToString() || x.relatedAddress == remoteEndPoint.Address.ToString()) &&
(x.port == remoteEndPoint.Port || x.relatedPort == remoteEndPoint.Port)))
{
// This STUN request has come from a socket not in the remote ICE candidates list. Add it so we can send our STUN binding request to it.
// RTCIceCandidate remoteIceCandidate = new IceCandidate("udp", remoteEndPoint.Address, (ushort)remoteEndPoint.Port, RTCIceCandidateType.host);
RTCIceCandidate peerRflxCandidate = new RTCIceCandidate(new RTCIceCandidateInit());
peerRflxCandidate.SetAddressProperties(RTCIceProtocol.udp, remoteEndPoint.Address, (ushort)remoteEndPoint.Port, RTCIceCandidateType.prflx, null, 0);
logger.LogDebug($"Adding peer reflex ICE candidate for {remoteEndPoint}.");
_remoteCandidates.Add(peerRflxCandidate);
// Some browsers require a STUN binding request from our end before the DTLS handshake will be initiated.
// The STUN connectivity checks are already scheduled but we can speed things up by sending a binding
// request immediately.
SendStunConnectivityChecks(null);
}
}
else if (stunMessage.Header.MessageType == STUNv2MessageTypesEnum.BindingSuccessResponse)
{
if (ConnectionState != RTCIceConnectionState.connected)
{
logger.LogDebug($"ICE session setting connected remote end point to {remoteEndPoint}.");
_connectedRemoteEndPoint = remoteEndPoint;
ConnectionState = RTCIceConnectionState.connected;
OnIceConnectionStateChange?.Invoke(RTCIceConnectionState.connected);
}
// TODO: What needs to be done here?
//if (_turnServerEndPoint != null && remoteEndPoint.ToString() == _turnServerEndPoint.ToString())
//{
// if (iceCandidate.IsGatheringComplete == false)
// {
// var reflexAddressAttribute = stunMessage.Attributes.FirstOrDefault(y => y.AttributeType == STUNv2AttributeTypesEnum.XORMappedAddress) as STUNv2XORAddressAttribute;
// if (reflexAddressAttribute != null)
// {
// iceCandidate.StunRflxIPEndPoint = new IPEndPoint(reflexAddressAttribute.Address, reflexAddressAttribute.Port);
// iceCandidate.IsGatheringComplete = true;
// logger.LogDebug("ICE gathering complete for local socket " + iceCandidate.RtpChannel.RTPLocalEndPoint + ", rflx address " + iceCandidate.StunRflxIPEndPoint + ".");
// }
// else
// {
// iceCandidate.IsGatheringComplete = true;
// logger.LogDebug("The STUN binding response received on " + iceCandidate.RtpChannel.RTPLocalEndPoint + " from " + remoteEndPoint + " did not have an XORMappedAddress attribute, rlfx address can not be determined.");
// }
// }
//}
//else
//{
// iceCandidate.LastStunResponseReceivedAt = DateTime.Now;
// if (iceCandidate.IsStunLocalExchangeComplete == false)
// {
// iceCandidate.IsStunLocalExchangeComplete = true;
// logger.LogDebug("WebRTC client STUN exchange complete for call " + CallID + ", candidate local socket " + iceCandidate.RtpChannel.RTPLocalEndPoint + ", remote socket " + remoteEndPoint + ".");
// SetIceConnectionState(IceConnectionStatesEnum.Connected);
// }
//}
}
else if (stunMessage.Header.MessageType == STUNv2MessageTypesEnum.BindingErrorResponse)
{
logger.LogWarning($"A STUN binding error response was received from {remoteEndPoint}.");
}
else
{
logger.LogWarning($"An unrecognised STUN request was received from {remoteEndPoint}.");
}
}
/// <summary>
/// Processes a received STUN request or response.
/// </summary>
/// <param name="stunMessage">The STUN message received.</param>
/// <param name="remoteEndPoint">The remote end point the STUN packet was received from.</param>
public void ProcessStunMessage(STUNv2Message stunMessage, IPEndPoint remoteEndPoint)
{
remoteEndPoint = (!remoteEndPoint.Address.IsIPv4MappedToIPv6) ? remoteEndPoint : new IPEndPoint(remoteEndPoint.Address.MapToIPv4(), remoteEndPoint.Port);
//logger.LogDebug($"STUN message received from remote {remoteEndPoint} {stunMessage.Header.MessageType}.");
if (stunMessage.Header.MessageType == STUNv2MessageTypesEnum.BindingRequest)
{
// TODO: The integrity check method needs to be implemented (currently just returns true).
bool result = stunMessage.CheckIntegrity(System.Text.Encoding.UTF8.GetBytes(LocalIcePassword), LocalIceUser, RemoteIceUser);
if (!result)
{
// Send STUN error response.
STUNv2Message stunErrResponse = new STUNv2Message(STUNv2MessageTypesEnum.BindingErrorResponse);
stunErrResponse.Header.TransactionId = stunMessage.Header.TransactionId;
_rtpChannel.SendAsync(RTPChannelSocketsEnum.RTP, remoteEndPoint, stunErrResponse.ToByteBuffer(null, false));
}
else
{
var matchingCandidate = (_remoteCandidates != null) ? _remoteCandidates.Where(x => x.IsEquivalentEndPoint(RTCIceProtocol.udp, remoteEndPoint)).FirstOrDefault() : null;
if (matchingCandidate == null)
{
// This STUN request has come from a socket not in the remote ICE candidates list.
// Add a new remote peer reflexive candidate.
RTCIceCandidate peerRflxCandidate = new RTCIceCandidate(new RTCIceCandidateInit());
peerRflxCandidate.SetAddressProperties(RTCIceProtocol.udp, remoteEndPoint.Address, (ushort)remoteEndPoint.Port, RTCIceCandidateType.prflx, null, 0);
logger.LogDebug($"Adding peer reflex ICE candidate for {remoteEndPoint}.");
_remoteCandidates.Add(peerRflxCandidate);
UpdateChecklist(peerRflxCandidate);
matchingCandidate = peerRflxCandidate;
}
// Find the checklist entry for this remote candidate and update its status.
var matchingChecklistEntry = _checklist.Where(x => x.RemoteCandidate.foundation == matchingCandidate.foundation).FirstOrDefault();
if (matchingChecklistEntry == null)
{
logger.LogWarning("ICE session STUN request matched a remote candidate but NOT a checklist entry.");
}
//else
//{
// if (!IsController)
// {
// matchingChecklistEntry.State = ChecklistEntryState.Succeeded;
// }
//}
// The UseCandidate attribute is only meant to be set by the "Controller" peer. This implementation
// will accept it irrespective of the peer roles. If the remote peer wants us to use a certain remote
// end point then so be it.
if (stunMessage.Attributes.Any(x => x.AttributeType == STUNv2AttributeTypesEnum.UseCandidate))
{
if (ConnectionState != RTCIceConnectionState.connected)
{
// If we are the "controlled" agent and get a "use candidate" attribute that sets the matching candidate as nominated
// as per https://tools.ietf.org/html/rfc8445#section-7.3.1.5.
if (matchingChecklistEntry == null)
{
logger.LogWarning("ICE session STUN request had UseCandidate set but no matching checklist entry was found.");
}
else
{
logger.LogDebug($"ICE session remote peer nominated entry from binding request: {matchingChecklistEntry.RemoteCandidate}");
SetNominatedEntry(matchingChecklistEntry);
}
}
}
STUNv2Message stunResponse = new STUNv2Message(STUNv2MessageTypesEnum.BindingSuccessResponse);
stunResponse.Header.TransactionId = stunMessage.Header.TransactionId;
stunResponse.AddXORMappedAddressAttribute(remoteEndPoint.Address, remoteEndPoint.Port);
string localIcePassword = LocalIcePassword;
byte[] stunRespBytes = stunResponse.ToByteBufferStringKey(localIcePassword, true);
_rtpChannel.SendAsync(RTPChannelSocketsEnum.RTP, remoteEndPoint, stunRespBytes);
}
}
else if (stunMessage.Header.MessageType == STUNv2MessageTypesEnum.BindingSuccessResponse)
{
// Correlate with request using transaction ID as per https://tools.ietf.org/html/rfc8445#section-7.2.5.
// Actions to take on a successful STUN response https://tools.ietf.org/html/rfc8445#section-7.2.5.3
// - Discover peer reflexive remote candidates
// (TODO: According to https://tools.ietf.org/html/rfc8445#section-7.2.5.3.1 peer reflexive get added to the local candidates list?)
// - Construct a valid pair which means match a candidate pair in the check list and mark it as valid (since a successful STUN exchange
// has now taken place on it). A new entry may need to be created for this pair since peer reflexive candidates are not added to the connectivity
// check checklist.
// - Update state of candidate pair that generated the check to Succeeded.
// - If the controlling candidate set the USE_CANDIDATE attribute then the ICE agent that receives the successful response sets the nominated
// flag of the pair to true. Once the nominated flag is set it concludes the ICE processing for that component.
if (_checklistState == ChecklistState.Running)
{
string txID = Encoding.ASCII.GetString(stunMessage.Header.TransactionId);
// Attempt to find the checklist entry for this transaction ID.
var matchingChecklistEntry = _checklist.Where(x => x.RequestTransactionID == txID).FirstOrDefault();
if (matchingChecklistEntry == null)
{
logger.LogWarning("ICE session STUN response transaction ID did not match a checklist entry.");
}
else
{
matchingChecklistEntry.State = ChecklistEntryState.Succeeded;
if (matchingChecklistEntry.Nominated)
{
logger.LogDebug($"ICE session remote peer nominated entry from binding response: {matchingChecklistEntry.RemoteCandidate}");
// This is the response to a connectivity check that had the "UseCandidate" attribute set.
SetNominatedEntry(matchingChecklistEntry);
}
else if (this.IsController && !_checklist.Any(x => x.Nominated))
{
// If we are the controlling ICE agent it's up to us to decide when to nominate a candidate pair to use for the connection.
// To start with we'll just use whichever pair gets the first successful STUN exchange. If needs be the selection algorithm can
// improve over time.
matchingChecklistEntry.ChecksSent = 0;
matchingChecklistEntry.LastCheckSentAt = DateTime.MinValue;
matchingChecklistEntry.Nominated = true;
SendConnectivityCheck(matchingChecklistEntry, true);
}
}
}
}
else if (stunMessage.Header.MessageType == STUNv2MessageTypesEnum.BindingErrorResponse)
{
logger.LogWarning($"A STUN binding error response was received from {remoteEndPoint}.");
// Attempt to find the checklist entry for this transaction ID.
string txID = Encoding.ASCII.GetString(stunMessage.Header.TransactionId);
var matchingChecklistEntry = _checklist.Where(x => x.RequestTransactionID == txID).FirstOrDefault();
if (matchingChecklistEntry == null)
{
logger.LogWarning("ICE session STUN error response transaction ID did not match a checklist entry.");
}
else
{
logger.LogWarning($"ICE session check list entry set to failed: {matchingChecklistEntry.RemoteCandidate}");
matchingChecklistEntry.State = ChecklistEntryState.Failed;
}
}
else
{
logger.LogWarning($"An unrecognised STUN request was received from {remoteEndPoint}.");
}
}