/// <summary>
/// Create a new SCTP association instance where the INIT will be generated
/// from this end of the connection.
/// </summary>
/// <param name="sctpTransport">The transport layer doing the actual sending and receiving of
/// packets, e.g. UDP, DTLS, raw sockets etc.</param>
/// <param name="destination">Optional. The remote destination end point for this association.
/// Some transports, such as DTLS, are already established and do not use this parameter.</param>
/// <param name="sctpSourcePort">The source port for the SCTP packet header.</param>
/// <param name="sctpDestinationPort">The destination port for the SCTP packet header.</param>
/// <param name="defaultMTU">The default Maximum Transmission Unit (MTU) for the underlying
/// transport. This determines the maximum size of an SCTP packet that will be used with
/// the transport.</param>
/// <param name="localTransportPort">Optional. The local transport (e.g. UDP or DTLS) port being
/// used for the underlying SCTP transport. This be set on the SCTP association's ID to aid in
/// diagnostics.</param>
public SctpAssociation(
SctpTransport sctpTransport,
IPEndPoint destination,
ushort sctpSourcePort,
ushort sctpDestinationPort,
ushort defaultMTU,
int localTransportPort,
ushort numberOutboundStreams = DEFAULT_NUMBER_OUTBOUND_STREAMS,
ushort numberInboundStreams = DEFAULT_NUMBER_INBOUND_STREAMS)
{
_sctpTransport = sctpTransport;
Destination = destination;
_sctpSourcePort = sctpSourcePort;
_sctpDestinationPort = sctpDestinationPort;
_defaultMTU = defaultMTU;
_numberOutboundStreams = numberOutboundStreams;
_numberInboundStreams = numberInboundStreams;
VerificationTag = Crypto.GetRandomUInt(true);
ID = $"{sctpSourcePort}:{sctpDestinationPort}:{localTransportPort}";
ARwnd = DEFAULT_ADVERTISED_RECEIVE_WINDOW;
_dataReceiver = new SctpDataReceiver(ARwnd, _defaultMTU, 0);
_dataSender = new SctpDataSender(ID, this.SendChunk, defaultMTU, Crypto.GetRandomUInt(true), DEFAULT_ADVERTISED_RECEIVE_WINDOW);
State = SctpAssociationState.Closed;
}
/// <summary>
/// Create a new SCTP association instance from the cookie that was previously
/// sent to the remote party in an INIT ACK chunk.
/// </summary>
public SctpAssociation(
SctpTransport sctpTransport,
SctpTransportCookie cookie,
int localTransportPort)
{
_sctpTransport = sctpTransport;
ID = $"{cookie.SourcePort}:{cookie.DestinationPort}:{localTransportPort}";
State = SctpAssociationState.Closed;
GotCookie(cookie);
}
/// <summary>
/// Event handler to coordinate changes to the SCTP association state with the overall
/// SCTP transport state.
/// </summary>
/// <param name="associationState">The state of the SCTP association.</param>
private void OnAssociationStateChanged(SctpAssociationState associationState)
{
if (associationState == SctpAssociationState.Established)
{
SetState(RTCSctpTransportState.Connected);
}
else if (associationState == SctpAssociationState.Closed)
{
SetState(RTCSctpTransportState.Closed);
}
}
/// <summary>
/// Updates the state of the association.
/// </summary>
/// <param name="state">The new association state.</param>
internal void SetState(SctpAssociationState state)
{
logger.LogTrace($"SCTP state for association {ID} changed to {state}.");
State = state;
OnAssociationStateChanged?.Invoke(state);
}
