/*
 * 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

#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) rand();
  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);
}
