sdp.c File Reference

Minimal SDP (RFC 4566) parse/generate for DataChannel offers/answers. More...

#include "webrtc_internal.h"
#include <stdio.h>
#include <string.h>

Include dependency graph for sdp.c:

Go to the source code of this file.

Functions
int	cwist_sdp_parse (const char *sdp, size_t len, cwist_sdp_info *info)
	Parse an SDP blob into a cwist_sdp_info structure.
int	cwist_sdp_write_answer (char *out, size_t cap, const char *fingerprint, const char *ufrag, const char *pwd, const char *mid, const char *host, uint16_t port)
	Generate an SDP answer for an ICE-lite DataChannel endpoint.
int	cwist_sdp_write_offer (char *out, size_t cap, const char *fingerprint, const char *ufrag, const char *pwd, const char *mid)
	Generate an SDP offer for a full (non-lite) DataChannel endpoint.

Detailed Description

Minimal SDP (RFC 4566) parse/generate for DataChannel offers/answers.

Supports only the subset of SDP needed for a single SCTP DataChannel m-section: ICE credentials, DTLS fingerprint/setup, mid, and ice-lite. Parsing extracts fields into a cwist_sdp_info struct; generation produces offer or answer strings with CRLF line endings.

Definition in file sdp.c.

Function Documentation

cwist_sdp_parse()

int cwist_sdp_parse	(	const char *	sdp,
		size_t	len,
		cwist_sdp_info *	info
	)

Parse an SDP blob into a cwist_sdp_info structure.

Parse the fields the ICE-lite agent needs from an SDP description.

Parameters

sdp	SDP text (not required to be NUL-terminated).
len	Length of sdp in bytes.
info	Output structure; zeroed first, then filled from recognized lines.

Returns

0 on success, -1 if ice-ufrag or ice-pwd is missing or empty.

Note

Lines longer than 511 bytes are truncated. If an attribute appears more than once, the last occurrence wins. Sets info->has_lite when "a=ice-lite" appears.

Definition at line 43 of file sdp.c.

References cap.

Referenced by cwist_webrtc_handle_offer().

cwist_sdp_write_answer()

int cwist_sdp_write_answer	(	char *	out,
		size_t	cap,
		const char *	fingerprint,
		const char *	ufrag,
		const char *	pwd,
		const char *	mid,
		const char *	host,
		uint16_t	port
	)

Generate an SDP answer for an ICE-lite DataChannel endpoint.

Write an ICE-lite, DTLS-passive DataChannel answer.

Parameters

out	Output buffer, receives CRLF-terminated SDP answer.
cap	Capacity of out in bytes.
fingerprint	DTLS certificate fingerprint (hex, colon-separated).
ufrag	ICE username fragment.
pwd	ICE password.
mid	Media section ID (also used in the BUNDLE group).
host	Local host address for the a=candidate line.
port	Local UDP port for the a=candidate line.

Returns

0 on success, -1 if the output was truncated or encoding failed.

Note

Declares ice-lite and hardcodes a=setup:passive, since the ICE-lite answering endpoint takes the passive DTLS role, and emits a single host candidate followed by end-of-candidates.

Definition at line 129 of file sdp.c.

References cap.

Referenced by cwist_webrtc_handle_offer().

cwist_sdp_write_offer()

int cwist_sdp_write_offer	(	char *	out,
		size_t	cap,
		const char *	fingerprint,
		const char *	ufrag,
		const char *	pwd,
		const char *	mid
	)

Generate an SDP offer for a full (non-lite) DataChannel endpoint.

Write a DTLS-active DataChannel offer (loopback tests).

Parameters

out	Output buffer, receives CRLF-terminated SDP offer.
cap	Capacity of out in bytes.
fingerprint	DTLS certificate fingerprint (hex, colon-separated).
ufrag	ICE username fragment.
pwd	ICE password.
mid	Media section ID (also used in the BUNDLE group).

Returns

0 on success, -1 if the output was truncated or encoding failed.

Note

Thin wrapper over write_session() with setup "active", no ice-lite, and a fixed session ID; the full agent offering endpoint takes the active DTLS role.

Definition at line 168 of file sdp.c.

References cap.