tor-browser

rtp.c (6553B)

---

/*
* rtp.c
*
* library functions for the real-time transport protocol
*
* David A. McGrew
* Cisco Systems, Inc.
*/

/*
*
* Copyright (c) 2001-2017, Cisco Systems, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
*   Redistributions of source code must retain the above copyright
*   notice, this list of conditions and the following disclaimer.
*
*   Redistributions in binary form must reproduce the above
*   copyright notice, this list of conditions and the following
*   disclaimer in the documentation and/or other materials provided
*   with the distribution.
*
*   Neither the name of the Cisco Systems, Inc. nor the names of its
*   contributors may be used to endorse or promote products derived
*   from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/

#include "rtp.h"

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

#include <sys/types.h>
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif

#include "cipher_priv.h"

#define PRINT_DEBUG 0   /* set to 1 to print out debugging data */
#define VERBOSE_DEBUG 0 /* set to 1 to print out more data      */

int rtp_sendto(rtp_sender_t sender, const void *msg, int len)
{
   int octets_sent;
   srtp_err_status_t stat;
   int pkt_len = len + RTP_HEADER_LEN;

   /* marshal data */
   strncpy(sender->message.body, msg, len);

   /* update header */
   sender->message.header.seq = ntohs(sender->message.header.seq) + 1;
   sender->message.header.seq = htons(sender->message.header.seq);
   sender->message.header.ts = ntohl(sender->message.header.ts) + 1;
   sender->message.header.ts = htonl(sender->message.header.ts);

   /* apply srtp */
   stat = srtp_protect(sender->srtp_ctx, &sender->message.header, &pkt_len);
   if (stat) {
#if PRINT_DEBUG
       fprintf(stderr, "error: srtp protection failed with code %d\n", stat);
#endif
       return -1;
   }
#if VERBOSE_DEBUG
   srtp_print_packet(&sender->message.header, pkt_len);
#endif
   octets_sent =
       sendto(sender->socket, (void *)&sender->message, pkt_len, 0,
              (struct sockaddr *)&sender->addr, sizeof(struct sockaddr_in));

   if (octets_sent != pkt_len) {
#if PRINT_DEBUG
       fprintf(stderr, "error: couldn't send message %s", (char *)msg);
       perror("");
#endif
   }

   return octets_sent;
}

int rtp_recvfrom(rtp_receiver_t receiver, void *msg, int *len)
{
   int octets_recvd;
   srtp_err_status_t stat;

   octets_recvd = recvfrom(receiver->socket, (void *)&receiver->message, *len,
                           0, (struct sockaddr *)NULL, 0);

   if (octets_recvd == -1) {
       *len = 0;
       return -1;
   }

   /* verify rtp header */
   if (receiver->message.header.version != 2) {
       *len = 0;
       return -1;
   }

#if PRINT_DEBUG
   fprintf(stderr, "%d octets received from SSRC %u\n", octets_recvd,
           receiver->message.header.ssrc);
#endif
#if VERBOSE_DEBUG
   srtp_print_packet(&receiver->message.header, octets_recvd);
#endif

   /* apply srtp */
   stat = srtp_unprotect(receiver->srtp_ctx, &receiver->message.header,
                         &octets_recvd);
   if (stat) {
       fprintf(stderr, "error: srtp unprotection failed with code %d%s\n",
               stat,
               stat == srtp_err_status_replay_fail ? " (replay check failed)"
               : stat == srtp_err_status_auth_fail ? " (auth check failed)"
                                                   : "");
       return -1;
   }
   strncpy(msg, receiver->message.body, octets_recvd);

   return octets_recvd;
}

int rtp_sender_init(rtp_sender_t sender,
                   int sock,
                   struct sockaddr_in addr,
                   unsigned int ssrc)
{
   /* set header values */
   sender->message.header.ssrc = htonl(ssrc);
   sender->message.header.ts = 0;
   sender->message.header.seq = (uint16_t)srtp_cipher_rand_u32_for_tests();
   sender->message.header.m = 0;
   sender->message.header.pt = 0x1;
   sender->message.header.version = 2;
   sender->message.header.p = 0;
   sender->message.header.x = 0;
   sender->message.header.cc = 0;

   /* set other stuff */
   sender->socket = sock;
   sender->addr = addr;

   return 0;
}

int rtp_receiver_init(rtp_receiver_t rcvr,
                     int sock,
                     struct sockaddr_in addr,
                     unsigned int ssrc)
{
   /* set header values */
   rcvr->message.header.ssrc = htonl(ssrc);
   rcvr->message.header.ts = 0;
   rcvr->message.header.seq = 0;
   rcvr->message.header.m = 0;
   rcvr->message.header.pt = 0x1;
   rcvr->message.header.version = 2;
   rcvr->message.header.p = 0;
   rcvr->message.header.x = 0;
   rcvr->message.header.cc = 0;

   /* set other stuff */
   rcvr->socket = sock;
   rcvr->addr = addr;

   return 0;
}

int rtp_sender_init_srtp(rtp_sender_t sender, const srtp_policy_t *policy)
{
   return srtp_create(&sender->srtp_ctx, policy);
}

int rtp_sender_deinit_srtp(rtp_sender_t sender)
{
   return srtp_dealloc(sender->srtp_ctx);
}

int rtp_receiver_init_srtp(rtp_receiver_t sender, const srtp_policy_t *policy)
{
   return srtp_create(&sender->srtp_ctx, policy);
}

int rtp_receiver_deinit_srtp(rtp_receiver_t sender)
{
   return srtp_dealloc(sender->srtp_ctx);
}

rtp_sender_t rtp_sender_alloc(void)
{
   return (rtp_sender_t)malloc(sizeof(rtp_sender_ctx_t));
}

void rtp_sender_dealloc(rtp_sender_t rtp_ctx)
{
   free(rtp_ctx);
}

rtp_receiver_t rtp_receiver_alloc(void)
{
   return (rtp_receiver_t)malloc(sizeof(rtp_receiver_ctx_t));
}

void rtp_receiver_dealloc(rtp_receiver_t rtp_ctx)
{
   free(rtp_ctx);
}