SDP utilities. More...

#include <string.h>
#include "sdp-utils.h"
#include "rtp.h"
#include "utils.h"
#include "debug.h"

Include dependency graph for sdp-utils.c:

Macros
#define	JANUS_BUFSIZE 16384

Functions
void	janus_sdp_destroy (janus_sdp *sdp)
	Method to destroy a Janus SDP object. More...

void	janus_sdp_mline_destroy (janus_sdp_mline *m)
	Helper method to free a janus_sdp_mline instance. More...

void	janus_sdp_attribute_destroy (janus_sdp_attribute *a)
	Helper method to free a janus_sdp_attribute instance. More...

janus_sdp_mline *	janus_sdp_mline_create (janus_sdp_mtype type, guint16 port, const char *proto, janus_sdp_mdirection direction)
	Helper method to quickly create a janus_sdp_mline instance. More...

janus_sdp_mline *	janus_sdp_mline_find (janus_sdp *sdp, janus_sdp_mtype type)
	Helper method to get the janus_sdp_mline associated to a media type. More...

janus_sdp_mline *	janus_sdp_mline_find_by_index (janus_sdp *sdp, int index)
	Helper method to get the janus_sdp_mline by its index. More...

int	janus_sdp_mline_remove (janus_sdp *sdp, janus_sdp_mtype type)
	Helper method to remove the janus_sdp_mline associated to a media type from the SDP. More...

janus_sdp_attribute *	janus_sdp_attribute_create (const char name, const char value,...)

int	janus_sdp_attribute_add_to_mline (janus_sdp_mline mline, janus_sdp_attribute attr)
	Helper method to add an attribute to a media line. More...

janus_sdp_mtype	janus_sdp_parse_mtype (const char *type)
	Helper method to get a janus_sdp_mtype from a string. More...

const char *	janus_sdp_mtype_str (janus_sdp_mtype type)
	Helper method to get the string associated to a janus_sdp_mtype value. More...

janus_sdp_mdirection	janus_sdp_parse_mdirection (const char *direction)
	Helper method to get a janus_sdp_mdirection from a string. More...

const char *	janus_sdp_mdirection_str (janus_sdp_mdirection direction)
	Helper method to get the string associated to a janus_sdp_mdirection value. More...

const char *	janus_sdp_oa_type_str (janus_sdp_oa_type type)

janus_sdp *	janus_sdp_parse (const char sdp, char error, size_t errlen)
	Method to parse an SDP string to a janus_sdp object. More...

int	janus_sdp_remove_payload_type (janus_sdp *sdp, int index, int pt)
	Helper method to quickly remove all traces (m-line, rtpmap, fmtp, etc.) of a payload type. More...

int	janus_sdp_get_codec_pt (janus_sdp sdp, int index, const char codec)
	Helper to get the payload type associated to a specific codec in an m-line. More...

const char *	janus_sdp_get_codec_name (janus_sdp *sdp, int index, int pt)
	Helper to get the codec name associated to a specific payload type in an m-line. More...

const char *	janus_sdp_get_codec_rtpmap (const char *codec)
	Helper to get the rtpmap associated to a specific codec. More...

char *	janus_sdp_write (janus_sdp *imported)
	Method to serialize a janus_sdp object to an SDP string. More...

void	janus_sdp_find_preferred_codec (janus_sdp sdp, janus_sdp_mtype type, int index, const char *codec)
	Helper method to return the preferred audio or video codec in an SDP offer or answer, (where by preferred we mean the codecs we prefer ourselves, and not the m-line SDP order) as long as the m-line direction is not disabled (port=0 or direction=inactive) in the SDP. More...

void	janus_sdp_find_first_codecs (janus_sdp sdp, janus_sdp_mtype type, int index, const char *codec)
	Helper method to return the first audio and video codecs in an SDP offer or answer, (no matter whether we personally prefer them ourselves or not) as long as the m-line direction is not disabled (port=0 or direction=inactive) in the SDP. More...

const char *	janus_sdp_match_preferred_codec (janus_sdp_mtype type, char *codec)
	Helper method to match a codec to one of the preferred codecs. More...

janus_sdp *	janus_sdp_new (const char name, const char address)
	Method to quickly generate a janus_sdp instance from a few selected fields. More...

janus_sdp *	janus_sdp_generate_offer (const char name, const char address,...)
	Method to generate a janus_sdp offer, using variable arguments to dictate what to negotiate (e.g., in terms of media to offer, directions, etc.). Variable arguments are in the form of a sequence of name-value terminated by a JANUS_SDP_OA_DONE, e.g.: More...

int	janus_sdp_generate_offer_mline (janus_sdp *offer,...)
	Method to add a single m-line to a new offer, using the same variable arguments janus_sdp_generate_offer supports. This is useful whenever you need to create a new offer, but don't know in advance how many m-lines you'll need, or it would be hard to do programmatically in a single call to janus_sdp_generate_offer. The first argument MUST be JANUS_SDP_OA_MLINE, specifying the type of the media. More...

janus_sdp *	janus_sdp_generate_answer (janus_sdp *offer)
	Method to generate a janus_sdp answer to a provided janus_sdp offer. Notice that this doesn't address the individual m-lines: it will just create an empty response, create the corresponding m-lines, but leave them all "rejected". To answer each m-line you'll have to iterate on the offer m-lines and call janus_sdp_generate_answer_mline instead, e.g.: More...

int	janus_sdp_generate_answer_mline (janus_sdp offer, janus_sdp answer, janus_sdp_mline *offered,...)
	Method to respond to a single m-line in an offer, using the same variable arguments janus_sdp_generate_offer_mline supports. The first argument MUST be JANUS_SDP_OA_MLINE, specifying the type of the media, e.g.: More...

Variables
const char *	janus_preferred_audio_codecs []

uint	janus_audio_codecs = sizeof(janus_preferred_audio_codecs)/sizeof(*janus_preferred_audio_codecs)

const char *	janus_preferred_video_codecs []

uint	janus_video_codecs = sizeof(janus_preferred_video_codecs)/sizeof(*janus_preferred_video_codecs)

Detailed Description

SDP utilities.

Author: Lorenzo Miniero loren.nosp@m.zo@m.nosp@m.eetec.nosp@m.ho.c.nosp@m.om

Copyright: GNU General Public License v3

Implementation of an internal SDP representation. Allows to parse SDP strings to an internal janus_sdp object, the manipulation of such object by playing with its properties, and a serialization to an SDP string that can be passed around. Since they don't have any core dependencies, these utilities can be used by plugins as well.

Core

Macro Definition Documentation

#define JANUS_BUFSIZE 16384

Function Documentation

int janus_sdp_attribute_add_to_mline	(	janus_sdp_mline *	mline,
		janus_sdp_attribute *	attr
	)

Helper method to add an attribute to a media line.

Parameters

[in]	mline	The m-line to add the attribute to
[in]	attr	The attribute to add

Returns: 0 in case of success, -1 otherwise

janus_sdp_attribute* janus_sdp_attribute_create	(	const char *	name,
		const char *	value,
			...
	)

void janus_sdp_attribute_destroy ( janus_sdp_attribute * attr )

Helper method to free a janus_sdp_attribute instance.

Note: This method does not remove the attribute from the global or m-line attributes, that's up to the caller

Parameters

[in] attr The janus_sdp_attribute instance to free

void janus_sdp_destroy ( janus_sdp * sdp )

Method to destroy a Janus SDP object.

Parameters

[in] sdp The Janus SDP object to free

void janus_sdp_find_first_codecs	(	janus_sdp *	sdp,
		janus_sdp_mtype	type,
		int	index,
		const char **	codec
	)

Helper method to return the first audio and video codecs in an SDP offer or answer, (no matter whether we personally prefer them ourselves or not) as long as the m-line direction is not disabled (port=0 or direction=inactive) in the SDP.

Note: The codec arguments is input/output, and it'll be set to a static value in janus_preferred_audio_codecs and janus_preferred_video_codecs, so don't free it.

Parameters

[in]	sdp	The Janus SDP object to parse
[in]	type	Whether we're looking at an audio or video codec
[in]	index	The m-line to refer to (use -1 for the first m-line that matches)
[out]	codec	The audio or video codec that was found

void janus_sdp_find_preferred_codec	(	janus_sdp *	sdp,
		janus_sdp_mtype	type,
		int	index,
		const char **	codec
	)

Helper method to return the preferred audio or video codec in an SDP offer or answer, (where by preferred we mean the codecs we prefer ourselves, and not the m-line SDP order) as long as the m-line direction is not disabled (port=0 or direction=inactive) in the SDP.

Note: The codec arguments is input/output, and it'll be set to a static value in janus_preferred_audio_codecs or janus_preferred_video_codecs, so don't free it.

Parameters

[in]	sdp	The Janus SDP object to parse
[in]	type	Whether we're looking at an audio or video codec
[in]	index	The m-line to refer to (use -1 for the first m-line that matches)
[out]	codec	The audio or video codec that was found

janus_sdp* janus_sdp_generate_answer ( janus_sdp * offer )

Method to generate a janus_sdp answer to a provided janus_sdp offer. Notice that this doesn't address the individual m-lines: it will just create an empty response, create the corresponding m-lines, but leave them all "rejected". To answer each m-line you'll have to iterate on the offer m-lines and call janus_sdp_generate_answer_mline instead, e.g.:

       janus_sdp *answer = janus_sdp_generate_answer(offer);
       GList *temp = offer->m_lines;
       while(temp) {
        janus_sdp_mline *m = (janus_sdp_mline *)temp->data;
        janus_sdp_generate_answer_mline(offer, answer, m,
                [..]
                JANUS_SDP_OA_DONE);
        temp = temp->next;
       }

Parameters

[in] offer The Janus SDP offer to respond to

Returns: A pointer to a janus_sdp object, if successful, NULL otherwise

int janus_sdp_generate_answer_mline	(	janus_sdp *	offer,
		janus_sdp *	answer,
		janus_sdp_mline *	offered,
			...
	)

Method to respond to a single m-line in an offer, using the same variable arguments janus_sdp_generate_offer_mline supports. The first argument MUST be JANUS_SDP_OA_MLINE, specifying the type of the media, e.g.:

       janus_sdp_generate_answer_mline(offer, answer, offer_mline,
        JANUS_SDP_OA_MLINE, JANUS_SDP_AUDIO,
                JANUS_SDP_OA_CODEC, "opus",
                JANUS_SDP_OA_DIRECTION, JANUS_SDP_RECVONLY,
        JANUS_SDP_OA_DONE);

to respond to an offered m-line with recvonly audio and use Opus.

Parameters

[in]	offer	The Janus SDP offer
[in]	answer	The Janus SDP answer to add the new m-line to
[in]	offered	The Janus SDP m-line from the offer to respond to

Returns: 0 if successful, a negative integer othwerwise

janus_sdp* janus_sdp_generate_offer	(	const char *	name,
		const char *	address,
			...
	)

Method to generate a janus_sdp offer, using variable arguments to dictate what to negotiate (e.g., in terms of media to offer, directions, etc.). Variable arguments are in the form of a sequence of name-value terminated by a JANUS_SDP_OA_DONE, e.g.:

       janus_sdp *offer = janus_sdp_generate_offer("My session", "127.0.0.1",
        JANUS_SDP_OA_MLINE, JANUS_SDP_AUDIO,
                JANUS_SDP_OA_PT, 100,
                JANUS_SDP_OA_DIRECTION, JANUS_SDP_SENDONLY,
                JANUS_SDP_OA_CODEC, "opus",
        JANUS_SDP_OA_MLINE, JANUS_SDP_VIDEO,
                JANUS_SDP_OA_PT, 101,
                JANUS_SDP_OA_DIRECTION, JANUS_SDP_RECVONLY,
                JANUS_SDP_OA_CODEC, "vp8",
        JANUS_SDP_OA_DONE);

to offer a sendonly Opus audio stream being offered with 100 as payload type, and a recvonly VP8 video stream with 101 as payload type. Refer to the property names in the header file for a complete list of how you can drive the offer. Other media streams can be added, as long as you prefix/specify them with JANUS_SDP_OA_MLINE as done here. The default, if not specified, is to not offer anything, meaning it will be up to you to add m-lines subsequently.

Parameters

[in]	name	The session name (if NULL, a default value will be set)
[in]	address	The IP to set in o= and c= fields (if NULL, a default value will be set)

Returns: A pointer to a janus_sdp object, if successful, NULL otherwise

int janus_sdp_generate_offer_mline	(	janus_sdp *	offer,
			...
	)

Method to add a single m-line to a new offer, using the same variable arguments janus_sdp_generate_offer supports. This is useful whenever you need to create a new offer, but don't know in advance how many m-lines you'll need, or it would be hard to do programmatically in a single call to janus_sdp_generate_offer. The first argument MUST be JANUS_SDP_OA_MLINE, specifying the type of the media.

Note: In case case you add audio and don't specify anything else, the default is to use Opus and payload type 111. For video, the default is VP8 and payload type 96. The default media direction is sendrecv.

Parameters

[in] offer The Janus SDP offer to add the new m-line to

Returns: 0 if successful, a negative integer othwerwise

const char* janus_sdp_get_codec_name	(	janus_sdp *	sdp,
		int	index,
		int	pt
	)

Helper to get the codec name associated to a specific payload type in an m-line.

Parameters

sdp	The Janus SDP instance to process
index	The m-line to refer to (use -1 for the first m-line that matches)
pt	The payload type to find

Returns: The codec name, if found, or NULL otherwise

int janus_sdp_get_codec_pt	(	janus_sdp *	sdp,
		int	index,
		const char *	codec
	)

Helper to get the payload type associated to a specific codec in an m-line.

Parameters

sdp	The Janus SDP instance to process
index	The m-line to refer to (use -1 for the first m-line that matches)
codec	The codec to find, as a string

Returns: The payload type, if found, or -1 otherwise

const char* janus_sdp_get_codec_rtpmap ( const char * codec )

Helper to get the rtpmap associated to a specific codec.

Parameters

codec The codec name, as a string (e.g., "opus")

Returns: The rtpmap value, if found (e.g., "opus/48000/2"), or NULL otherwise

const char* janus_sdp_match_preferred_codec	(	janus_sdp_mtype	type,
		char *	codec
	)

Helper method to match a codec to one of the preferred codecs.

Note: Don't free the returned value, as it's a constant value

Parameters

[in]	type	The type of media to match
[in]	codec	The codec to match

Returns: The codec, if found, or NULL otherwise

const char* janus_sdp_mdirection_str ( janus_sdp_mdirection direction )

Helper method to get the string associated to a janus_sdp_mdirection value.

Parameters

[in] direction The direction to stringify

Returns: The direction as a string, if valid, or NULL otherwise

janus_sdp_mline* janus_sdp_mline_create	(	janus_sdp_mtype	type,
		guint16	port,
		const char *	proto,
		janus_sdp_mdirection	direction
	)

Helper method to quickly create a janus_sdp_mline instance.

Note: The type_str property of the new m-line is created automatically depending on the provided type attribute. If type is JANUS_SDP_OTHER, though, type_str will NOT we allocated, and will be up to the caller.

Parameters

[in]	type	Type of the media (audio/video/application) as a janus_sdp_mtype
[in]	port	Port to advertise
[in]	proto	Profile to advertise
[in]	direction	Direction of the media as a janus_sdp_direction

Returns: A pointer to a valid janus_sdp_mline instance, if successfull, NULL otherwise

void janus_sdp_mline_destroy ( janus_sdp_mline * mline )

Helper method to free a janus_sdp_mline instance.

Note: This method does not remove the m-line from the janus_sdp instance, that's up to the caller

Parameters

[in] mline The janus_sdp_mline instance to free

janus_sdp_mline* janus_sdp_mline_find	(	janus_sdp *	sdp,
		janus_sdp_mtype	type
	)

Helper method to get the janus_sdp_mline associated to a media type.

Note: This currently returns the first m-line of the specified type it finds: as such, it's only here for backwards compatibility with plugins not doing multistream.

Parameters

[in]	sdp	The Janus SDP object to search
[in]	type	The type of media to search

Returns: The janus_sdp_mline instance, if found, or NULL otherwise

janus_sdp_mline* janus_sdp_mline_find_by_index	(	janus_sdp *	sdp,
		int	index
	)

Helper method to get the janus_sdp_mline by its index.

Parameters

[in]	sdp	The Janus SDP object to search
[in]	index	The index of the m-line in the SDP

Returns: The janus_sdp_mline instance, if found, or NULL otherwise

int janus_sdp_mline_remove	(	janus_sdp *	sdp,
		janus_sdp_mtype	type
	)

Helper method to remove the janus_sdp_mline associated to a media type from the SDP.

Note: This currently removes the first m-line of the specified type it finds: as such, it's only here for backwards compatibility with plugins not doing multistream.

Parameters

[in]	sdp	The Janus SDP object to modify
[in]	type	The type of media to remove

Returns: 0 if successful, a negative integer otherwise

const char* janus_sdp_mtype_str ( janus_sdp_mtype type )

Helper method to get the string associated to a janus_sdp_mtype value.

Parameters

[in] type The type to stringify

Returns: The type as a string, if valid, or NULL otherwise

janus_sdp* janus_sdp_new	(	const char *	name,
		const char *	address
	)

Method to quickly generate a janus_sdp instance from a few selected fields.

Note: This allocates the o_addr, s_name and c_addr properties: if you want to replace them, don't forget to g_free the original pointers first.

Parameters

[in]	name	The session name (if NULL, a default value will be set)
[in]	address	The IP to set in o= and c= fields (if NULL, a default value will be set)

Returns: A pointer to a janus_sdp object, if successful, NULL otherwise

const char* janus_sdp_oa_type_str ( janus_sdp_oa_type type )

janus_sdp* janus_sdp_parse	(	const char *	sdp,
		char *	error,
		size_t	errlen
	)

Method to parse an SDP string to a janus_sdp object.

Parameters

[in]	sdp	The SDP string to parse
[in,out]	error	Buffer to receive a reason for an error, if any
[in]	errlen	The length of the error buffer

Returns: A pointer to a janus_sdp object, if successful, NULL otherwise; in case of errors, if provided the error string is filled with a reason

janus_sdp_mdirection janus_sdp_parse_mdirection ( const char * direction )

Helper method to get a janus_sdp_mdirection from a string.

Parameters

[in] direction The direction to parse as a string (e.g., "sendrecv")

Returns: The corresponding janus_sdp_mdirection value

janus_sdp_mtype janus_sdp_parse_mtype ( const char * type )

Helper method to get a janus_sdp_mtype from a string.

Parameters

[in] type The type to parse as a string (e.g., "audio")

Returns: The corresponding janus_sdp_mtype value

int janus_sdp_remove_payload_type	(	janus_sdp *	sdp,
		int	index,
		int	pt
	)

Helper method to quickly remove all traces (m-line, rtpmap, fmtp, etc.) of a payload type.

Parameters

[in]	sdp	The janus_sdp object to remove the payload type from
[in]	index	The m-line to remove the payload type from (use -1 for the first m-line that matches)
[in]	pt	The payload type to remove

Returns: 0 in case of success, a negative integer otherwise

char* janus_sdp_write ( janus_sdp * sdp )

Method to serialize a janus_sdp object to an SDP string.

Parameters

[in] sdp The janus_sdp object to serialize

Returns: A pointer to a string with the serialized SDP, if successful, NULL otherwise

Variable Documentation

uint janus_audio_codecs = sizeof(janus_preferred_audio_codecs)/sizeof(*janus_preferred_audio_codecs)

const char* janus_preferred_audio_codecs[]

Initial value:

= {
        "opus", "pcmu", "pcma", "g722", "isac16", "isac32"
}

const char* janus_preferred_video_codecs[]

Initial value:

= {
        "vp8", "vp9", "h264"
}

uint janus_video_codecs = sizeof(janus_preferred_video_codecs)/sizeof(*janus_preferred_video_codecs)

Macros

Functions

Variables

Detailed Description

Macro Definition Documentation

Function Documentation

Variable Documentation