Class Sdp

Class for processing the Session Description Protocol message contents of a SIP message. See RFC 8866.

Inheritance

object

Sdp

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

Namespace: SipLib.Sdp

Assembly: SipLib.dll

Syntax

public class Sdp

Constructors

Sdp(IPAddress, string)

Constructs a new Sdp and initializes the Origin (o=), ConnectionData (c=), session name (s=) and an empty media list.

Declaration

public Sdp(IPAddress LocalIp, string UaName)

Parameters

Type	Name	Description
IPAddress	LocalIp	Local IP address
string	UaName	User agent or server name

Properties

Attributes

Contains the attributes for this media session.

Declaration

public List<SdpAttribute> Attributes { get; set; }

Property Value

Type	Description
List<SdpAttribute>

Bandwidth

Bandwidth parameter (b) for the entire session. See Section 5.8 of RFC 8866. This parameter is optional. Treating it as a simple string.

Declaration

public string Bandwidth { get; set; }

Property Value

Type	Description
string

ConnectionData

Contains the connecton data for the call.

Declaration

public ConnectionData? ConnectionData { get; set; }

Property Value

Type	Description
ConnectionData

Email

Contains the e-mail parameter (e) for the session. See Section 5.6 of RFC 8866. This parameter is optional.

Declaration

public string Email { get; set; }

Property Value

Type	Description
string

Media

Contains a list of all of the different types of media for a call.

Declaration

public List<MediaDescription> Media { get; set; }

Property Value

Type	Description
List<MediaDescription>

MediaDirection

Gets or sets the media direction attribute for the session level.

Declaration

public MediaDirectionEnum MediaDirection { get; set; }

Property Value

Type	Description
MediaDirectionEnum

Origin

Contains the origin information for the "o" parameter. See Section 5.2 of RFC 8866.

Declaration

public Origin? Origin { get; set; }

Property Value

Type	Description
Origin

PhoneNumber

Contains the phone number (p) parameter for the session. See Section 5.6 of RFC 8866. This parameter is optional.

Declaration

public string PhoneNumber { get; set; }

Property Value

Type	Description
string

SessionInformation

Contains the session information "i" parameter. See Section 5.4 of RFC 8866. This parameter is optional.

Declaration

public string SessionInformation { get; set; }

Property Value

Type	Description
string

SessionName

Contains the Session Name for the "s" type. parameter Section 5.3 of RFC 8866.

Declaration

public string SessionName { get; set; }

Property Value

Type	Description
string

Timing

Timing (t) parameter. See Section 5.9 of RFC 8866.

Declaration

public string Timing { get; set; }

Property Value

Type	Description
string

Uri

Contains a URI to more information about the session. This is the "u" parameter. See Section 5.5 of RFC 8866. This parameter is optional.

Declaration

public string Uri { get; set; }

Property Value

Type	Description
string

Version

Contains the version number (v) of the SDP protocol. This is expected to be always 0. See Section 5.1 of RFC 8866.

Declaration

public int Version { get; }

Property Value

Type	Description
int

Methods

BuildAnswerSdp(Sdp, IPAddress, SdpAnswerSettings)

Builds an Sdp object to send as the answered Sdp in responsed to the offered Sdp

Declaration

public static Sdp BuildAnswerSdp(Sdp OfferedSdp, IPAddress address, SdpAnswerSettings AnswerSettings)

Parameters

Type	Name	Description
Sdp	OfferedSdp	SDP that was offered
IPAddress	address	IP address to be used for transport of all media. This address is used in the "c=" line of the SDP.
SdpAnswerSettings	AnswerSettings	Settings that determine how to build the answered SDP

Returns

Type	Description
Sdp	Returns the SDP to send to the client that offered the SDP

BuildAudioAnswerMediaDescription(MediaDescription, SdpAnswerSettings, int)

Builds a MediaDescription object for audio for sending as an answer to an offered media description

Declaration

public static MediaDescription BuildAudioAnswerMediaDescription(MediaDescription OfferedMd, SdpAnswerSettings Settings, int LocalPortToUse)

Parameters

Type	Name	Description
MediaDescription	OfferedMd	Media description that was offered for audio
SdpAnswerSettings	Settings	Settings that determine how to build the answer media description
int	LocalPortToUse	Local port number used by the current RtpChannel for audio. Set to zero if there currently is no audio RtpChannel. If set to 0 then a port will be assigned by the port manager.

Returns

Type	Description
MediaDescription	Returns a new MediaDescription to send in the SDP of an OK response.

BuildMsrpAnswerMediaDescription(MediaDescription, IPAddress, SdpAnswerSettings, MsrpUri?)

Builds a MediaDescription object for MSRP for sending as an answer to an offered media description

Declaration

public static MediaDescription BuildMsrpAnswerMediaDescription(MediaDescription OfferedMd, IPAddress Address, SdpAnswerSettings Settings, MsrpUri? LocalMsrpUriToUse)

Parameters

Type	Name	Description
MediaDescription	OfferedMd	Media description that was offered for MSRP
IPAddress	Address	Local IP address to use for the transport of MSRP
SdpAnswerSettings	Settings	Settings that determine how to build the answer media description
MsrpUri	LocalMsrpUriToUse	Set to the MsrpUri if there is a MsrpConnection for MSRP. Set to null if there is currently no MSRP for the call. If null then a new local port will be assigned by the port manager and a new local MsrpUri object will be created.

Returns

Type	Description
MediaDescription	Returns a new MediaDescription to send in the SDP of an OK response.

BuildOfferSdp(IPAddress, SdpOfferSettings, X509Certificate2?)

Builds an Sdp object to send with the INVITE request for a new call.

Declaration

public static Sdp BuildOfferSdp(IPAddress address, SdpOfferSettings offerSettings, X509Certificate2? msrpCert)

Parameters

Type	Name	Description
IPAddress	address	IP address to be used for transport of all media. This address is used in the "c=" line of the SDP.
SdpOfferSettings	offerSettings	Configuration settings that specify what media types to offer and the types of codecs to offer for each media type.
X509Certificate2	msrpCert	X.509 certificate to use for MSRP. This may be null if not offering MSRP. It must be non-null if offering MSRP and the offerSettings.MsrpSetupType is not active.

Returns

Type	Description
Sdp	Returns a new Sdp object to send with an INVITE request.

BuildReInviteAnswerSdp(Sdp, IPAddress, SdpAnswerSettings, int, int, int, MsrpUri?)

Builds an Sdp object to send as the answered Sdp in response to the offered Sdp in a re-INVITE request

Declaration

public static Sdp BuildReInviteAnswerSdp(Sdp OfferedSdp, IPAddress address, SdpAnswerSettings AnswerSettings, int LocalAudioPort, int LocalVideoPort, int LocalRttPort, MsrpUri? localMsrpUri)

Parameters

Type	Name	Description
Sdp	OfferedSdp	SDP that was offered in the re-INVITE
IPAddress	address	Local IP address to be used for transport of all media. This address is used in the "c=" line of the SDP.
SdpAnswerSettings	AnswerSettings	Settings that determine how to build the answered SDP
int	LocalAudioPort	Local port number used by the current RtpChannel for audio. Set to zero if there currently is no audio RtpChannel. If set to 0 then a port will be assigned by the port manager.
int	LocalVideoPort	Local port number used by the current RtpChannel for video. Set to zero if there curently is no video RtpChannel. If set to 0 then a port will be assigned by the port manager.
int	LocalRttPort	Local port number used by the current RtpChannel for RTT. Set to zero if there is currently no RTT RtpChannel. If set to 0 then a port will be assigned by the port manager.
MsrpUri	localMsrpUri	Set to the MsrpUri if there is a MsrpConnection for MSRP. Set to null if there is currently no MSRP for the call. If null then a new local port will be assigned by the port manager and a new local MsrpUri object will be created.

Returns

Type	Description
Sdp	Returns the SDP to send to the client that offered the SDP

BuildRttAnswerMediaDescription(MediaDescription, SdpAnswerSettings, int)

Builds a MediaDescription object for RTT for sending as an answer to an offered media description

Declaration

public static MediaDescription BuildRttAnswerMediaDescription(MediaDescription OfferedMd, SdpAnswerSettings Settings, int LocalPortToUse)

Parameters

Type	Name	Description
MediaDescription	OfferedMd	Media description that was offered for RTT
SdpAnswerSettings	Settings	Settings that determine how to build the answer media description
int	LocalPortToUse	Local port number used by the current RtpChannel for RTT. Set to zero if there currently is no RTT RtpChannel. If set to 0 then a port will be assigned by the port manager.

Returns

Type	Description
MediaDescription	Returns a new MediaDescription to send in the SDP of an OK response.

BuildVideoAnswerMediaDescription(MediaDescription, SdpAnswerSettings, int)

Builds a MediaDescription object for video for sending as an answer to an offered media description

Declaration

public static MediaDescription BuildVideoAnswerMediaDescription(MediaDescription OfferedMd, SdpAnswerSettings Settings, int LocalPortToUse)

Parameters

Type	Name	Description
MediaDescription	OfferedMd	Media description that was offered for video
SdpAnswerSettings	Settings	Settings that determine how to build the answer media description
int	LocalPortToUse	Local port number used by the current RtpChannel for video. Set to zero if there currently is no video RtpChannel. If set to 0 then a port will be assigned by the port manager.

Returns

Type	Description
MediaDescription	Returns a new MediaDescription to send in the SDP of an OK response.

CreateCopy()

Creates a deep copy (i.e. by-value) of this object.

Declaration

public Sdp CreateCopy()

Returns

Type	Description
Sdp	Returns a new Sdp object.

GetAudioConnectionData(ref string?, ref int)

Retrieves the IP address and the port number for the audio media in this SDP.

Declaration

public bool GetAudioConnectionData(ref string? strIpAddr, ref int Port)

Parameters

Type	Name	Description
string	strIpAddr	IP address to send the audio to. This output will contain the IP address if this method returns true or it will be set to null if this method returns false.
int	Port	Port number to send the audio to. This output will contain the port number to if this method returns true or it will be set to 0 if this function returns false.

Returns

Type	Description
bool	Returns true if the audio media type is present and valid. Else returns null.

GetMediaByTypeAndLabel(string, string)

Gets the MediaDescription object for the specified media type and media label attribute.

Declaration

public MediaDescription? GetMediaByTypeAndLabel(string strType, string LabelAttribute)

Parameters

Type	Name	Description
string	strType	The media type to search for (audio, video, message or text)
string	LabelAttribute	Value of the label attribute to seach for.

Returns

Type	Description
MediaDescription	Returns a MediaDescription object if the specified media type and label exist or null if not found.

GetMediaDirection(Sdp, MediaDescription)

Gets the media direction attribute for a media type. The media direction may be specified at the session level or at the media level. The media level has priority.

Declaration

public static MediaDirectionEnum GetMediaDirection(Sdp sdp, MediaDescription md)

Parameters

Type	Name	Description
Sdp	sdp	Session data
MediaDescription	md	Media description. Must be one of the MediaDescription objects in the SDP.

Returns

Type	Description
MediaDirectionEnum	Returns the media direction if specified at the media level or the session level. Returns MediaDirectionEnum.sendrecv if the direction is not specified at either level.

GetMediaEndPoint(Sdp, MediaDescription)

Gets the IPEndPoint for media given the offered SDP and the offered SDP Media Description for that media. The destination IP address may be specified at the session level or the media level.

Declaration

public static IPEndPoint? GetMediaEndPoint(Sdp Sdp, MediaDescription Md)

Parameters

Type	Name	Description
Sdp	Sdp	The entire SDP block that was offered.
MediaDescription	Md	The SDP Media Description block for the media to get the IP address for.

Returns

Type	Description
IPEndPoint	Returns an IPAddress. Returns null if there was no address specified in the session or media levels.

GetMediaIPAddr(Sdp, MediaDescription)

Gets the destination IP address for media given the offered SDP and the offered SDP Media Description for that media. The destination IP address may be specified at the session level or the media level.

Declaration

public static IPAddress? GetMediaIPAddr(Sdp Sdp, MediaDescription Smd)

Parameters

Type	Name	Description
Sdp	Sdp	The entire SDP block that was offered.
MediaDescription	Smd	The SDP Media Description block for the media to get the IP address for.

Returns

Type	Description
IPAddress	Returns an IPAddress. Returns null if there was no address specified in the session or media levels.

GetMediaType(string)

Gets the MediaDescription object for the specified type of media.

Declaration

public MediaDescription? GetMediaType(string strType)

Parameters

Type	Name	Description
string	strType	Type of media such as audio, video, text, etc..

Returns

Type	Description
MediaDescription	Returns the SepMediaDescription object if the specified type of media is present or null if it is not.

GetMediaTypeIndex(string)

Gets the index of a specified media type in the Media list.

Declaration

public int GetMediaTypeIndex(string strType)

Parameters

Type	Name	Description
string	strType	Type of media to look for. Must be "audio", "video", "text" or "message"

Returns

Type	Description
int	Returns the index of the media type in the Media list. Returns -1 if the media type is not present.

GetMediaTypeList(string)

Gets a list of MediaDescription objects in the SDP that have the same type of media.

Declaration

public List<MediaDescription> GetMediaTypeList(string strType)

Parameters

Type	Name	Description
string	strType	Media type. Must be one of "audio", "video", "text" or "message"

Returns

Type	Description
List<MediaDescription>	Returns a list of MediaDescription objects of the same media type. The return value will not be null.

GetNamedAttribute(string)

Returns the SdpAttribute object for a named attribute for the entire SDP at the session level.

Declaration

public SdpAttribute? GetNamedAttribute(string strAttr)

Parameters

Type	Name	Description
string	strAttr	Name of the attribute to search for.

Returns

Type	Description
SdpAttribute	Returns a SdpAttribute for the named attribute if it is found or null if the named attribute is not present.

HasMultiMedia()

Checks to see if the offered SDP has media other that "audio" that is a known media type.

Declaration

public bool HasMultiMedia()

Returns

Type	Description
bool	Returns true if the SDP contains media other than "audio" or false does not.

MediaTypeToDisplayString(string)

Returns a display name for the associated media type name.

Declaration

public static string MediaTypeToDisplayString(string mediaTypeName)

Parameters

Type	Name	Description
string	mediaTypeName	Media type name. Should be one of "audio", "video", "message" or "text".

Returns

Type	Description
string	Return a name for displaying.

ParseSDP(string)

Parses the SDP contained in a string

Declaration

public static Sdp ParseSDP(string strSdp)

Parameters

Type	Name	Description
string	strSdp	Contains a SDP SIP body part.

Returns

Type	Description
Sdp	Returns a new Sdp object.

Exceptions

Type	Condition
ArgumentException	Thrown if an invalid argument is detected
Exception	Thrown if an unexpected error occurs

RemoveNamedAttribute(string)

Removes all instances of a named SDP attribute.

Declaration

public void RemoveNamedAttribute(string strAttr)

Parameters

Type	Name	Description
string	strAttr	Name of the SDP attribute to remove.

ToString()

Converts the Sdp object to a string.

Declaration

public override string ToString()

Returns

Type	Description
string	The string is formatted so that it can be appended to a SIP message as the SDP contents.

Overrides

object.ToString()