Class SctpTransport

Contains the common methods that an SCTP transport layer needs to implement. As well as being able to be carried directly in IP packets, SCTP packets can also be wrapped in higher level protocols.

Inheritance

System.Object

SctpTransport

RTCSctpTransport

SctpUdpTransport

Inherited Members

System.Object.Equals(System.Object)

System.Object.Equals(System.Object, System.Object)

System.Object.GetHashCode()

System.Object.GetType()

System.Object.MemberwiseClone()

System.Object.ReferenceEquals(System.Object, System.Object)

System.Object.ToString()

Namespace: SIPSorcery.Net

Assembly: SIPSorcery.dll

Syntax

public abstract class SctpTransport

Fields

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DEFAULT_COOKIE_LIFETIME_SECONDS

As per https://tools.ietf.org/html/rfc4960#section-15.

Declaration

public const int DEFAULT_COOKIE_LIFETIME_SECONDS = 60

Field Value

Type	Description
System.Int32

Properties

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IsPortAgnostic

This property can be used to indicate whether an SCTP transport layer is port agnostic. For example a DTLS transport is likely to only ever create a single SCTP association and the SCTP ports are redundant for matching end points. This allows the checks done on received SCTP packets to be more accepting about the ports used in the SCTP packet header.

Declaration

public virtual bool IsPortAgnostic { get; }

Property Value

Type	Description
System.Boolean	True if the transport implementation does not rely on the SCTP source and destination port for end point matching. False if it does.

Methods

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Abort(String)

Ungracefully closes an association. Any locally queued user data will be discarded, and an ABORT chunk is sent to the peer.

Declaration

public void Abort(string associationID)

Parameters

Type	Name	Description
System.String	associationID	Local handle to the SCTP association.

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Associate(IPAddress, Int32)

Initiates an association to a specific peer end point

Declaration

public string Associate(IPAddress destination, int streamCount)

Parameters

Type	Name	Description
System.Net.IPAddress	destination
System.Int32	streamCount

Returns

Type	Description
System.String	An association ID, which is a local handle to the SCTP association.

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ChangeHeartbeat(String, Int32)

Instructs the local endpoint to enable or disable heartbeat on the specified destination transport address.

Declaration

public string ChangeHeartbeat(string associationID, int interval)

Parameters

Type	Name	Description
System.String	associationID	Local handle to the SCTP association.
System.Int32	interval	Indicates the frequency of the heartbeat if this is to enable heartbeat on a destination transport address. This value is added to the RTO of the destination transport address.This value, if present, affects all destinations.

Returns

Type	Description
System.String

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Destroy(String)

Release the resources for the specified SCTP instance.

Declaration

public void Destroy(string instanceName)

Parameters

Type	Name	Description
System.String	instanceName

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GetCookie(SctpPacket)

Attempts to retrieve the cookie that should have been set by this peer from a COOKIE ECHO chunk. This is the step in the handshake that a new SCTP association will be created for a remote party. Providing the state cookie is valid create a new association.

Declaration

protected SctpTransportCookie GetCookie(SctpPacket sctpPacket)

Parameters

Type	Name	Description
SctpPacket	sctpPacket	The packet containing the COOKIE ECHO chunk received from the remote party.

Returns

Type	Description
SctpTransportCookie	If the state cookie in the chunk is valid a new SCTP association will be returned. IF it's not valid an empty cookie will be returned and an error response gets sent to the peer.

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GetCookieHMAC(Byte[])

Checks whether the state cookie that is supplied in a COOKIE ECHO chunk is valid for this SCTP transport.

Declaration

protected string GetCookieHMAC(byte[] buffer)

Parameters

Type	Name	Description
System.Byte[]	buffer	The buffer holding the state cookie.

Returns

Type	Description
System.String	True if the cookie is determined as valid, false if not.

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GetInitAck(SctpPacket, IPEndPoint)

Creates the INIT ACK chunk and packet to send as a response to an SCTP packet containing an INIT chunk.

Declaration

protected SctpPacket GetInitAck(SctpPacket initPacket, IPEndPoint remoteEP)

Parameters

Type	Name	Description
SctpPacket	initPacket	The received packet containing the INIT chunk.
System.Net.IPEndPoint	remoteEP	Optional. The remote IP end point the INIT packet was received on. For transports that don't use an IP transport directly this parameter can be set to null and it will not form part of the COOKIE ECHO checks.

Returns

Type	Description
SctpPacket	An SCTP packet with a single INIT ACK chunk.

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GetInitAckCookie(UInt16, UInt16, UInt32, UInt32, UInt32, String, Int32)

Gets a cookie to send in an INIT ACK chunk. This method is overloadable so that different transports can tailor how the cookie is created. For example the WebRTC SCTP transport only ever uses a single association so the local Tag and TSN properties must be the same rather than random.

Declaration

protected virtual SctpTransportCookie GetInitAckCookie(ushort sourcePort, ushort destinationPort, uint remoteTag, uint remoteTSN, uint remoteARwnd, string remoteEndPoint, int lifeTimeExtension = 0)

Parameters

Type	Name	Description
System.UInt16	sourcePort
System.UInt16	destinationPort
System.UInt32	remoteTag
System.UInt32	remoteTSN
System.UInt32	remoteARwnd
System.String	remoteEndPoint
System.Int32	lifeTimeExtension

Returns

Type	Description
SctpTransportCookie

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GetSrttReport(String)

Instructs the local SCTP to report the current Smoothed Round Trip Time (SRTT) measurement on the specified destination transport address of the given association.

Declaration

public int GetSrttReport(string associationID)

Parameters

Type	Name	Description
System.String	associationID	Local handle to the SCTP association.

Returns

Type	Description
System.Int32	An integer containing the most recent SRTT in milliseconds.

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GotInit(SctpPacket, IPEndPoint)

Declaration

protected void GotInit(SctpPacket initPacket, IPEndPoint remoteEndPoint)

Parameters

Type	Name	Description
SctpPacket	initPacket
System.Net.IPEndPoint	remoteEndPoint

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Initialize(UInt16)

This method allows SCTP to initialise its internal data structures and allocate necessary resources for setting up its operation environment.

Declaration

public string Initialize(ushort localPort)

Parameters

Type	Name	Description
System.UInt16	localPort	SCTP port number, if the application wants it to be specified.

Returns

Type	Description
System.String	The local SCTP instance name.

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Receive(String, Byte[], Int32, Int32)

This method shall read the first user message in the SCTP in-queue into the buffer specified by the application, if there is one available.The size of the message read, in bytes, will be returned.

Declaration

public int Receive(string associationID, byte[] buffer, int length, int streamID)

Parameters

Type	Name	Description
System.String	associationID	Local handle to the SCTP association.
System.Byte[]	buffer	The buffer to place the received data into.
System.Int32	length	The maximum size of the data to receive.
System.Int32	streamID	Optional. If specified indicates which stream to receive the data on.

Returns

Type	Description
System.Int32

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ReceiveUnacknowledged(String, Byte[], Int32, Int32)

Declaration

public void ReceiveUnacknowledged(string dataRetrievalID, byte[] buffer, int length, int streamID)

Parameters

Type	Name	Description
System.String	dataRetrievalID	The identification passed to the application in the failure notification.
System.Byte[]	buffer	The buffer to store the received message.
System.Int32	length	The maximum size of the data to receive.
System.Int32	streamID	This is a return value that is set to indicate which stream the data was sent to.

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ReceiveUnsent(String, Byte[], Int32, Int32)

Declaration

public void ReceiveUnsent(string dataRetrievalID, byte[] buffer, int length, int streamID)

Parameters

Type	Name	Description
System.String	dataRetrievalID	The identification passed to the application in the failure notification.
System.Byte[]	buffer	The buffer to store the received message.
System.Int32	length	The maximum size of the data to receive.
System.Int32	streamID	This is a return value that is set to indicate which stream the data was sent to.

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RequestHeartbeat(String)

Instructs the local endpoint to perform a HeartBeat on the specified destination transport address of the given association.

Declaration

public string RequestHeartbeat(string associationID)

Parameters

Type	Name	Description
System.String	associationID	Local handle to the SCTP association.

Returns

Type	Description
System.String	Indicates whether the transmission of the HEARTBEAT chunk to the destination address is successful.

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Send(String, Byte[], Int32, Int32)

Declaration

public abstract void Send(string associationID, byte[] buffer, int offset, int length)

Parameters

Type	Name	Description
System.String	associationID
System.Byte[]	buffer
System.Int32	offset
System.Int32	length

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Send(String, Byte[], Int32, Int32, Int32, Int32)

This is the main method to send user data via SCTP.

Declaration

public string Send(string associationID, byte[] buffer, int length, int contextID, int streamID, int lifeTime)

Parameters

Type	Name	Description
System.String	associationID	Local handle to the SCTP association.
System.Byte[]	buffer	The buffer holding the data to send.
System.Int32	length	The number of bytes from the buffer to send.
System.Int32	contextID	Optional. A 32-bit integer that will be carried in the sending failure notification to the application if the transportation of this user message fails.
System.Int32	streamID	Optional. To indicate which stream to send the data on. If not specified, stream 0 will be used.
System.Int32	lifeTime	Optional. specifies the life time of the user data. The user data will not be sent by SCTP after the life time expires.This parameter can be used to avoid efforts to transmit stale user messages.

Returns

Type	Description
System.String

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SetPrimary(String)

Instructs the local SCTP to use the specified destination transport address as the primary path for sending packets.

Declaration

public string SetPrimary(string associationID)

Parameters

Type	Name	Description
System.String	associationID

Returns

Type	Description
System.String

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SetProtocolParameters(String, Object)

This method allows the local SCTP to customise the protocol parameters.

Declaration

public void SetProtocolParameters(string associationID, object protocolParameters)

Parameters

Type	Name	Description
System.String	associationID	Local handle to the SCTP association.
System.Object	protocolParameters	The specific names and values of the protocol parameters that the SCTP user wishes to customise.

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Shutdown(String)

Gracefully closes an association. Any locally queued user data will be delivered to the peer.The association will be terminated only after the peer acknowledges all the SCTP packets sent.

Declaration

public void Shutdown(string associationID)

Parameters

Type	Name	Description
System.String	associationID	Local handle to the SCTP association.

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Status(String)

Returns the current status of the association.

Declaration

public SctpStatus Status(string associationID)

Parameters

Type	Name	Description
System.String	associationID	Local handle to the SCTP association.

Returns

Type	Description
SctpStatus

Extension Methods

JSONWriter.ToJson(Object)