srtp.c

mediastreamer2是开源的网络传输媒体流的库

/*
  The oRTP library is an RTP (Realtime Transport Protocol - rfc3550) stack.
  Copyright (C) 2001  Simon MORLAT [e-mail]

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#if defined(WIN32) || defined(_WIN32_WCE)
#include "ortp-config-win32.h"
#else
#include "ortp-config.h"
#endif
#include "ortp/ortp.h"

#ifdef HAVE_SRTP

#undef PACKAGE_NAME 
#undef PACKAGE_STRING
#undef PACKAGE_TARNAME 
#undef PACKAGE_VERSION

#include "ortp/srtp.h"

#define SRTP_PAD_BYTES 64 /*?? */

static int  srtp_sendto(RtpTransport *t, mblk_t *m, int flags, const struct sockaddr *to, socklen_t tolen){
	srtp_t srtp=(srtp_t)t->data;
	int slen;
	err_status_t err;
	/* enlarge the buffer for srtp to write its data */
	msgpullup(m,msgdsize(m)+SRTP_PAD_BYTES);
	slen=m->b_wptr-m->b_rptr;
	err=srtp_protect(srtp,m->b_rptr,&slen);
	if (err==err_status_ok){
		return sendto(t->session->rtp.socket,m->b_rptr,slen,flags,to,tolen);
	}
	ortp_error("srtp_protect() failed");
	return -1;
}

static int srtp_recvfrom(RtpTransport *t, mblk_t *m, int flags, struct sockaddr *from, socklen_t *fromlen){
	srtp_t srtp=(srtp_t)t->data;
	int err;
	int slen;
	err=recvfrom(t->session->rtp.socket,m->b_wptr,m->b_datap->db_lim-m->b_datap->db_base,flags,from,fromlen);
	if (err>0){

		/* keep NON-RTP data unencrypted */
		rtp_header_t *rtp;
		if (err>=RTP_FIXED_HEADER_SIZE)
		{
			rtp = (rtp_header_t*)m->b_wptr;
			if (rtp->version!=2)
			{
				return err;
			}
		}

		slen=err;
		if (srtp_unprotect(srtp,m->b_wptr,&slen)==err_status_ok)
			return slen;
		else {
			ortp_error("srtp_unprotect() failed");
			return -1;
		}
	}
	return err;
}

static int  srtcp_sendto(RtpTransport *t, mblk_t *m, int flags, const struct sockaddr *to, socklen_t tolen){
	srtp_t srtp=(srtp_t)t->data;
	int slen;
	/* enlarge the buffer for srtp to write its data */
	msgpullup(m,msgdsize(m)+SRTP_PAD_BYTES);
	slen=m->b_wptr-m->b_rptr;
	if (srtp_protect_rtcp(srtp,m->b_rptr,&slen)==err_status_ok){
		return sendto(t->session->rtcp.socket,m->b_rptr,slen,flags,to,tolen);
	}
	ortp_error("srtp_protect_rtcp() failed");
	return -1;
}

static int srtcp_recvfrom(RtpTransport *t, mblk_t *m, int flags, struct sockaddr *from, socklen_t *fromlen){
	srtp_t srtp=(srtp_t)t->data;
	int err;
	int slen;
	err=recvfrom(t->session->rtcp.socket,m->b_wptr,m->b_datap->db_lim-m->b_datap->db_base,flags,from,fromlen);
	if (err>0){
		slen=err;
		if (srtp_unprotect_rtcp(srtp,m->b_wptr,&slen)==err_status_ok)
			return slen;
		else {
			ortp_error("srtp_unprotect_rtcp() failed");
			return -1;
		}
	}
	return err;
}

ortp_socket_t 
srtp_getsocket(RtpTransport *t)
{
  return t->session->rtp.socket;
}

ortp_socket_t 
srtcp_getsocket(RtpTransport *t)
{
  return t->session->rtcp.socket;
}

/**
 * Creates a pair of Secure-RTP/Secure-RTCP RtpTransport's.
 * oRTP relies on libsrtp (see http://srtp.sf.net ) for secure RTP encryption.
 * This function creates a RtpTransport object to be used to the RtpSession using
 * rtp_session_set_transport().
 * @srtp: the srtp_t session to be used
 * 
**/
int srtp_transport_new(srtp_t srtp, RtpTransport **rtpt, RtpTransport **rtcpt ){
	if (rtpt) {
		(*rtpt)=ortp_new(RtpTransport,1);
		(*rtpt)->data=srtp;
		(*rtpt)->t_getsocket=srtp_getsocket;
		(*rtpt)->t_sendto=srtp_sendto;
		(*rtpt)->t_recvfrom=srtp_recvfrom;
	}
	if (rtcpt) {
		(*rtcpt)=ortp_new(RtpTransport,1);
		(*rtcpt)->data=srtp;
		(*rtcpt)->t_getsocket=srtcp_getsocket;
		(*rtcpt)->t_sendto=srtcp_sendto;
		(*rtcpt)->t_recvfrom=srtcp_recvfrom;
	}
	return 0;
}

err_status_t ortp_srtp_init(void)
{
	return srtp_init();
}

err_status_t ortp_srtp_create(srtp_t *session, const srtp_policy_t *policy)
{
	int i;
	i = srtp_create(session, policy);
	return i;
}

err_status_t ortp_srtp_dealloc(srtp_t session)
{
	return srtp_dealloc(session);
}

err_status_t ortp_srtp_add_stream(srtp_t session, const srtp_policy_t *policy)
{
	return srtp_add_stream(session, policy);
}

bool_t ortp_srtp_supported(void){
	return TRUE;
}

#else

int srtp_transport_new(void *i, RtpTransport **rtpt, RtpTransport **rtcpt ){
	ortp_error("srtp_transport_new: oRTP has not been compiled with SRTP support.");
	return -1;
}

bool_t ortp_srtp_supported(void){
	return FALSE;
}

int ortp_srtp_create(void *i, const void *policy)
{
	return -1;
}

int ortp_srtp_dealloc(void *session)
{
	return -1;
}

int ortp_srtp_add_stream(void *session, const void *policy)
{
	return -1;
}

#endif