Class SIPTransport

Inheritance

System.Object

SIPTransport

Implements

System.IDisposable

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.SIP

Assembly: SIPSorcery.dll

Syntax

public class SIPTransport : IDisposable

Constructors

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SIPTransport()

Creates a SIP transport class with default DNS resolver and SIP transaction engine.

Declaration

public SIPTransport()

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SIPTransport(Boolean)

Declaration

public SIPTransport(bool stateless)

Parameters

Type	Name	Description
System.Boolean	stateless

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SIPTransport(Boolean, Encoding, Encoding)

Allows the transport layer to be created to operate in a stateless mode.

Declaration

public SIPTransport(bool stateless, Encoding sipEncoding, Encoding sipBodyEncoding)

Parameters

Type	Name	Description
System.Boolean	stateless	If true the transport layer will NOT queue incoming messages and will NOT use a transaction engine.
System.Text.Encoding	sipEncoding
System.Text.Encoding	sipBodyEncoding

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SIPTransport(Encoding, Encoding)

Declaration

public SIPTransport(Encoding sipEncoding, Encoding sipBodyEncoding)

Parameters

Type	Name	Description
System.Text.Encoding	sipEncoding
System.Text.Encoding	sipBodyEncoding

Fields

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BlackholeAddress

Declaration

public static IPAddress BlackholeAddress

Field Value

Type	Description
System.Net.IPAddress

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ContactHost

If set this host name (or IP address) will be set whenever the transport layer is asked to do a substitution on the Contact URI. The substitution is requested by a request or response setting the Contact URI host to IPAddress.Any ("0.0.0.0") or IPAddress.IPV6.Any ("::0").

var sipRequest = GetRequest(
  method,
  uri,
  new SIPToHeader(
    null, 
    new SIPURI(uri.User, uri.Host, null, uri.Scheme, SIPProtocolsEnum.udp), 
    null),
  SIPFromHeader.GetDefaultSIPFromHeader(uri.Scheme));

// Set the Contact header to a default value that lets the transport layer know to update it
// when the sending socket is selected.
sipRequest.Header.Contact = new List<SIPContactHeader>() { SIPContactHeader.GetDefaultSIPContactHeader() };

Declaration

public string ContactHost

Field Value

Type	Description
System.String

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CustomiseRequestHeader

Optional callback function that can be set to customise the headers on an outbound SIP request. The callback is called BEFORE applying ContactHost which means do not set both if the callback is intended to set the Contact URI. Parameters:

SIPEndPoint: The local SIP end point the request will be sent from.
SIPEndPoint: The remote SIP end point the request has been resolved to.
SIPRequest: The SIP request being sent. Returns: If the result is non-null it will be used to replace the current SIP Header instance on the SIP Request. If null the original header will be left in place.

Declaration

public Func<SIPEndPoint, SIPEndPoint, SIPRequest, SIPHeader> CustomiseRequestHeader

Field Value

Type	Description
System.Func<SIPEndPoint, SIPEndPoint, SIPRequest, SIPHeader>

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CustomiseResponseHeader

Optional function that can be set to customise the headers on an outbound SIP request. The callback is called BEFORE applying ContactHost which means do not set both if the callback is intended to set the Contact URI. Parameters:

SIPEndPoint: The local SIP end point the request will be sent from.
SIPEndPoint: The remote SIP end point the request has been resolved to.
SIPRequest: The SIP request being sent. Returns: If the result is non-null it will be used to replace the current SIP Header instance on the SIP Request. If null the original header will be left in place.

Declaration

public Func<SIPEndPoint, SIPEndPoint, SIPResponse, SIPHeader> CustomiseResponseHeader

Field Value

Type	Description
System.Func<SIPEndPoint, SIPEndPoint, SIPResponse, SIPHeader>

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PreferIPv6NameResolution

Set to true to prefer IPv6 lookups of hostnames. By default IPv4 lookups will be performed.

Declaration

public bool PreferIPv6NameResolution

Field Value

Type	Description
System.Boolean

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ResolveSIPUriCallbackAsync

Default call to do DNS lookups for SIP URI's. In normal circumstances this property does not need to be set manually and care needs to be taken if it is. Can be replaced for custom scenarios and unit testing.

Declaration

public ResolveSIPUriDelegateAsync ResolveSIPUriCallbackAsync

Field Value

Type	Description
ResolveSIPUriDelegateAsync

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ResolveSIPUriFromCacheCallback

Default call to do DNS lookups for SIP URI's from cache and avoid a time consuming full DNS lookup. In normal circumstances this property does not need to be set manually and care needs to be taken if it is. Can be replaced for custom scenarios and unit testing.

Declaration

public ResolveSIPUriFromCacheDelegate ResolveSIPUriFromCacheCallback

Field Value

Type	Description
ResolveSIPUriFromCacheDelegate

Properties

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CanCreateMissingChannels

If true allows this class to attempt to create a new SIP channel if a required protocol is missing. Set to false to prevent new channels being created on demand. Note that when listening SIP end points are required they will always need to be created manually.

Declaration

public bool CanCreateMissingChannels { get; set; }

Property Value

Type	Description
System.Boolean

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DisableRetransmitSending

Warning: Do not set this property unless there is a specific problem with a remote SIP User Agent accepting SIP retransmits. The effect of setting this property is to only send each request and response for a transaction once, i.e. retransmits timers firing will not cause additional sending of the requests or responses to be put on the wire. SIP transaction processing will still occur as normal with the exception of not sending the retransmitted messages. It's also only likely to be useful for cases where reliable transports, such as TCP and TLS, are being used, since they are the ones where retransmits have been observed to be misidentified.

Declaration

public bool DisableRetransmitSending { get; set; }

Property Value

Type	Description
System.Boolean

Remarks

For additional context see https://lists.cs.columbia.edu/pipermail/sip-implementors/2013-January/028817.html and https://github.com/sipsorcery/sipsorcery/issues/370#issuecomment-739495726.

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MaxInMessageQueueCount

The maximum number of SIP message receiving queues, if this number is exceeded, new messages will be discarded directly Default:5000,Unlimited:0

Declaration

public int MaxInMessageQueueCount { get; set; }

Property Value

Type	Description
System.Int32

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MaxPendingTransactionsCount

Warning: Do not set this property unless you explicitly require a very high number of in-flight SIP transactions. The default limit is high and increasing it is likely to have a significant impact on CPU and memory performance.

Declaration

public static int MaxPendingTransactionsCount { get; set; }

Property Value

Type	Description
System.Int32

Methods

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AddSIPChannel(SIPChannel)

Adds an additional SIP Channel to the transport layer.

Declaration

public void AddSIPChannel(SIPChannel sipChannel)

Parameters

Type	Name	Description
SIPChannel	sipChannel

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AddSIPChannel(List<SIPChannel>)

Adds additional SIP Channels to the transport layer.

Declaration

public void AddSIPChannel(List<SIPChannel> sipChannels)

Parameters

Type	Name	Description
System.Collections.Generic.List<SIPChannel>	sipChannels

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CreateChannel(SIPProtocolsEnum, AddressFamily, Int32)

Creates an on demand SIP channel suitable for outbound connections.

Declaration

public SIPChannel CreateChannel(SIPProtocolsEnum protocol, AddressFamily addressFamily, int port = 0)

Parameters

Type	Name	Description
SIPProtocolsEnum	protocol	The transport protocol of the SIP channel to create.
System.Net.Sockets.AddressFamily	addressFamily	Whether the channel should be created for IPv4 or IPv6.
System.Int32	port	Optional. If specified channels that open a listener will attempt to use this port.

Returns

Type	Description
SIPChannel	A SIP channel if it was possible to create or null if not.

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Dispose()

Declaration

public void Dispose()

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EnableTraceLogs()

Helper method to enable logging of SIP request, responses and retransmits.

Declaration

public void EnableTraceLogs()

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GetSIPChannels()

Gets a list of this transport's SIP channels.

Declaration

public List<SIPChannel> GetSIPChannels()

Returns

Type	Description
System.Collections.Generic.List<SIPChannel>	A list of SIP channels.

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PreProcessRouteInfo(SIPRequest)

This function performs processing on a request to handle any actions that need to be taken based on the Route header.

Declaration

public void PreProcessRouteInfo(SIPRequest sipRequest)

Parameters

Type	Name	Description
SIPRequest	sipRequest

Remarks

The main sections in the RFC3261 dealing with Route header processing are sections 12.2.1.1 for request processing and 16.4 for proxy processing. The steps to process requests for Route headers are:

If route set is empty no further action is required, forward to destination resolved from request URI,
If the request URI is identified as a value that was previously set as a Route by this SIP agent it means the previous hop was a strict router. Replace the request URI with the last Route header and go to next step,
If the top most route header was set by this SIP agent then remove it and go to next step,
If the top most route set does contain the lr parameter then forward to the destination resolved by it,
If the top most route header does NOT contain the lr parameter is must be popped and inserted as the request URI and the original request URI must be added to the end of the route set, forward to destination resolved from request URI,

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ReceiveMessage(SIPChannel, SIPEndPoint, SIPEndPoint, Byte[])

Event handler for messages received on all SIP channels assigned to this transport. There are two distinct modes of operation for processing messages depending on whether the queue incoming variable is set. If it is then new messages get added to a queue and are processed on a separate thread. If not then the message is processed on the same thread that received the message. Generally only applications that do minimal processing, such as a stateless SIP Proxy, should do without the queueing. The biggest blocking risk is DNS. If the message is processed on the SIP channel thread and results in a DNS lookup then new receives could be blocked for up to 10s.

Declaration

public Task ReceiveMessage(SIPChannel sipChannel, SIPEndPoint localEndPoint, SIPEndPoint remoteEndPoint, byte[] buffer)

Parameters

Type	Name	Description
SIPChannel	sipChannel	The SIP channel that received the message.
SIPEndPoint	localEndPoint	The local end point the message was received on.
SIPEndPoint	remoteEndPoint	The remote end point the message came from.
System.Byte[]	buffer	A buffer containing the received message.

Returns

Type	Description
System.Threading.Tasks.Task

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RemoveSIPChannel(SIPChannel)

Removes a single SIP channel from the transport layer.

Declaration

public void RemoveSIPChannel(SIPChannel sipChannel)

Parameters

Type	Name	Description
SIPChannel	sipChannel	The SIP channel to remove.

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ResolveSIPUriAsync(SIPURI)

Public wrapper for the SIP DNS lookup call being used by this SIP transport.

Declaration

public Task<SIPEndPoint> ResolveSIPUriAsync(SIPURI uri)

Parameters

Type	Name	Description
SIPURI	uri	The SIP URI to resolve.

Returns

Type	Description
System.Threading.Tasks.Task<SIPEndPoint>	If successful a SIP end point for the SIP URI. For failures SIPEndPoint.Empty.

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SendRawAsync(SIPEndPoint, SIPEndPoint, Byte[])

Allows raw bytes to be sent from one of the SIPTransport sockets. This should not be used for SIP payloads and instead is provided to allow other types of payloads to be multiplexed on the SIP socket. Examples are sending NAT keep-alives and STUN responses where it's useful to use the same socket as the SIP packets.

Declaration

public Task<SocketError> SendRawAsync(SIPEndPoint localSIPEndPoint, SIPEndPoint dstEndPoint, byte[] buffer)

Parameters

Type	Name	Description
SIPEndPoint	localSIPEndPoint	The local SIP end point to do the send from. Must match the local end point of one of the SIP transports channels.
SIPEndPoint	dstEndPoint	The destination end point to send the buffer to.
System.Byte[]	buffer	The data buffer to send.

Returns

Type	Description
System.Threading.Tasks.Task<System.Net.Sockets.SocketError>

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SendRequestAsync(SIPEndPoint, SIPRequest)

Sends a SIP request asynchronously. This method will attempt to find the most appropriate local SIP channel in this SIP transport to send the request on.

Declaration

public Task<SocketError> SendRequestAsync(SIPEndPoint dstEndPoint, SIPRequest sipRequest)

Parameters

Type	Name	Description
SIPEndPoint	dstEndPoint	The destination end point to send the request to.
SIPRequest	sipRequest	The SIP request to send.

Returns

Type	Description
System.Threading.Tasks.Task<System.Net.Sockets.SocketError>

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SendRequestAsync(SIPRequest, Boolean)

This send method does NOT wait if a DNS lookup is required. Instead it relies on the SIP retransmit logic to avoid to re-attempt the send at pre-defined intervals. This type of send is suitable for requests that are part of a transaction or for SIP Proxy servers that are relying on the remote SIP agent to retransmit requests.

Declaration

public async Task<SocketError> SendRequestAsync(SIPRequest sipRequest, bool waitForDns = false)

Parameters

Type	Name	Description
SIPRequest	sipRequest	The SIP request to send.
System.Boolean	waitForDns	If true the request will wait for any required DNS lookup to complete. This can potentially take many seconds. If false the DNS lookup will be queued and the send will need to be called again.

Returns

Type	Description
System.Threading.Tasks.Task<System.Net.Sockets.SocketError>	Will return InPorgress for a DNS cache miss. HostNotFound for a cache hit on a failure response. Otherwise the result of the send attempt.

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SendResponseAsync(SIPEndPoint, SIPResponse)

Asynchronously forwards a SIP response to the specified destination.

Declaration

public Task<SocketError> SendResponseAsync(SIPEndPoint dstEndPoint, SIPResponse sipResponse)

Parameters

Type	Name	Description
SIPEndPoint	dstEndPoint	The destination end point to send the response to.
SIPResponse	sipResponse	The SIP response to send.

Returns

Type	Description
System.Threading.Tasks.Task<System.Net.Sockets.SocketError>

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SendResponseAsync(SIPResponse, Boolean)

Forwards a SIP response. There are two main cases for a SIP response to be forwarded:

First case is when we have processed a request and are returning a response. In this case the response should be sent back on exactly the same socket the request came on.
Second case is when we are acting as a Proxy and the response is on it's way back from the agent that processed the request. In this case it's highly likely the response needs to be forwarded to a different end point then the one it came from and it's also possible it will need to use a completely different channel to send on compared to the one it arrived on.

Forwarding logic:

If the channel hints are set then an attempt will be made to use them to find an appropriate channel to send the response on. If the hinted channel can't be found or it is found but is the wrong protocol then move onto the next step,
The information in the Top Via header will be used to find the best channel to forward the response on. This is a special send method that relies on the SIP transaction retransmit logic to avoid blocking when a DNS request is required. This type of send is suitable for responses that are part of a transaction or for SIP Proxy servers that are relying on the remote SIP agent to retransmit requests.

Declaration

public async Task<SocketError> SendResponseAsync(SIPResponse sipResponse, bool waitForDns = false)

Parameters

Type	Name	Description
SIPResponse	sipResponse	The SIP response to send.
System.Boolean	waitForDns	If true the request will wait for any required DNS lookup to complete. This can potentially take many seconds. If false the DNS lookup will be queued and the send will need to be called again.

Returns

Type	Description
System.Threading.Tasks.Task<System.Net.Sockets.SocketError>	Will return InPorgress for a DNS cache miss. HostNotFound for a cache hit on a failure response. Otherwise the result of the send attempt.

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Shutdown()

Shuts down the SIP transport layer by closing all SIP channels and stopping long running tasks.

Declaration

public void Shutdown()

Events

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SIPBadRequestInTraceEvent

Declaration

public event SIPTransportSIPBadMessageDelegate SIPBadRequestInTraceEvent

Event Type

Type	Description
SIPTransportSIPBadMessageDelegate

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SIPBadResponseInTraceEvent

Declaration

public event SIPTransportSIPBadMessageDelegate SIPBadResponseInTraceEvent

Event Type

Type	Description
SIPTransportSIPBadMessageDelegate

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SIPRequestInTraceEvent

Declaration

public event SIPTransportRequestTraceDelegate SIPRequestInTraceEvent

Event Type

Type	Description
SIPTransportRequestTraceDelegate

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SIPRequestOutTraceEvent

Declaration

public event SIPTransportRequestTraceDelegate SIPRequestOutTraceEvent

Event Type

Type	Description
SIPTransportRequestTraceDelegate

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SIPRequestRetransmitTraceEvent

Declaration

public event SIPTransactionRequestRetransmitDelegate SIPRequestRetransmitTraceEvent

Event Type

Type	Description
SIPTransactionRequestRetransmitDelegate

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SIPResponseInTraceEvent

Declaration

public event SIPTransportResponseTraceDelegate SIPResponseInTraceEvent

Event Type

Type	Description
SIPTransportResponseTraceDelegate

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SIPResponseOutTraceEvent

Declaration

public event SIPTransportResponseTraceDelegate SIPResponseOutTraceEvent

Event Type

Type	Description
SIPTransportResponseTraceDelegate

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SIPResponseRetransmitTraceEvent

Declaration

public event SIPTransactionResponseRetransmitDelegate SIPResponseRetransmitTraceEvent

Event Type

Type	Description
SIPTransactionResponseRetransmitDelegate

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SIPTransportRequestReceived

Declaration

public event SIPTransportRequestAsyncDelegate SIPTransportRequestReceived

Event Type

Type	Description
SIPTransportRequestAsyncDelegate

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SIPTransportResponseReceived

Declaration

public event SIPTransportResponseAsyncDelegate SIPTransportResponseReceived

Event Type

Type	Description
SIPTransportResponseAsyncDelegate

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STUNRequestReceived

Declaration

public event STUNRequestReceivedDelegate STUNRequestReceived

Event Type

Type	Description
STUNRequestReceivedDelegate

Implements

System.IDisposable

Extension Methods

JSONWriter.ToJson(Object)