1 /*
2 * rtp.c
3 *
4 * library functions for the real-time transport protocol
5 *
6 * David A. McGrew
7 * Cisco Systems, Inc.
8 */
9
10
11 #include "rtp_priv.h"
12
13 #include <stdio.h>
14 #include <string.h>
15
16 #include <sys/types.h>
17 #ifdef HAVE_SYS_SOCKET_H
18 # include <sys/socket.h>
19 #endif
20
21 #define PRINT_DEBUG 0 /* set to 1 to print out debugging data */
22 #define VERBOSE_DEBUG 0 /* set to 1 to print out more data */
23
24 unsigned int
rtp_sendto(rtp_sender_t sender,const void * msg,int len)25 rtp_sendto(rtp_sender_t sender, const void* msg, int len) {
26 int octets_sent;
27 err_status_t stat;
28 int pkt_len = len + RTP_HEADER_LEN;
29
30 /* marshal data */
31 strncpy(sender->message.body, msg, len);
32
33 /* update header */
34 sender->message.header.seq = ntohs(sender->message.header.seq) + 1;
35 sender->message.header.seq = htons(sender->message.header.seq);
36 sender->message.header.ts = ntohl(sender->message.header.ts) + 1;
37 sender->message.header.ts = htonl(sender->message.header.ts);
38
39 /* apply srtp */
40 stat = srtp_protect(sender->srtp_ctx, &sender->message.header, &pkt_len);
41 if (stat) {
42 #if PRINT_DEBUG
43 fprintf(stderr, "error: srtp protection failed with code %d\n", stat);
44 #endif
45 return -1;
46 }
47 #if VERBOSE_DEBUG
48 srtp_print_packet(&sender->message.header, pkt_len);
49 #endif
50 octets_sent = sendto(sender->socket, (void*)&sender->message,
51 pkt_len, 0, (struct sockaddr *)&sender->addr,
52 sizeof (struct sockaddr_in));
53
54 if (octets_sent != pkt_len) {
55 #if PRINT_DEBUG
56 fprintf(stderr, "error: couldn't send message %s", (char *)msg);
57 perror("");
58 #endif
59 }
60
61 return octets_sent;
62 }
63
64 unsigned int
rtp_recvfrom(rtp_receiver_t receiver,void * msg,int * len)65 rtp_recvfrom(rtp_receiver_t receiver, void *msg, int *len) {
66 int octets_recvd;
67 err_status_t stat;
68
69 octets_recvd = recvfrom(receiver->socket, (void *)&receiver->message,
70 *len, 0, (struct sockaddr *) NULL, 0);
71
72 /* verify rtp header */
73 if (receiver->message.header.version != 2) {
74 *len = 0;
75 return -1;
76 }
77
78 #if PRINT_DEBUG
79 fprintf(stderr, "%d octets received from SSRC %u\n",
80 octets_recvd, receiver->message.header.ssrc);
81 #endif
82 #if VERBOSE_DEBUG
83 srtp_print_packet(&receiver->message.header, octets_recvd);
84 #endif
85
86 /* apply srtp */
87 stat = srtp_unprotect(receiver->srtp_ctx,
88 &receiver->message.header, &octets_recvd);
89 if (stat) {
90 fprintf(stderr,
91 "error: srtp unprotection failed with code %d%s\n", stat,
92 stat == err_status_replay_fail ? " (replay check failed)" :
93 stat == err_status_auth_fail ? " (auth check failed)" : "");
94 return -1;
95 }
96 strncpy(msg, receiver->message.body, octets_recvd);
97
98 return octets_recvd;
99 }
100
101 int
rtp_sender_init(rtp_sender_t sender,int socket,struct sockaddr_in addr,unsigned int ssrc)102 rtp_sender_init(rtp_sender_t sender,
103 int socket,
104 struct sockaddr_in addr,
105 unsigned int ssrc) {
106
107 /* set header values */
108 sender->message.header.ssrc = htonl(ssrc);
109 sender->message.header.ts = 0;
110 sender->message.header.seq = (uint16_t) rand();
111 sender->message.header.m = 0;
112 sender->message.header.pt = 0x1;
113 sender->message.header.version = 2;
114 sender->message.header.p = 0;
115 sender->message.header.x = 0;
116 sender->message.header.cc = 0;
117
118 /* set other stuff */
119 sender->socket = socket;
120 sender->addr = addr;
121
122 return 0;
123 }
124
125 int
rtp_receiver_init(rtp_receiver_t rcvr,int socket,struct sockaddr_in addr,unsigned int ssrc)126 rtp_receiver_init(rtp_receiver_t rcvr,
127 int socket,
128 struct sockaddr_in addr,
129 unsigned int ssrc) {
130
131 /* set header values */
132 rcvr->message.header.ssrc = htonl(ssrc);
133 rcvr->message.header.ts = 0;
134 rcvr->message.header.seq = 0;
135 rcvr->message.header.m = 0;
136 rcvr->message.header.pt = 0x1;
137 rcvr->message.header.version = 2;
138 rcvr->message.header.p = 0;
139 rcvr->message.header.x = 0;
140 rcvr->message.header.cc = 0;
141
142 /* set other stuff */
143 rcvr->socket = socket;
144 rcvr->addr = addr;
145
146 return 0;
147 }
148
149 int
rtp_sender_init_srtp(rtp_sender_t sender,const srtp_policy_t * policy)150 rtp_sender_init_srtp(rtp_sender_t sender, const srtp_policy_t *policy) {
151 return srtp_create(&sender->srtp_ctx, policy);
152 }
153
154 int
rtp_receiver_init_srtp(rtp_receiver_t sender,const srtp_policy_t * policy)155 rtp_receiver_init_srtp(rtp_receiver_t sender, const srtp_policy_t *policy) {
156 return srtp_create(&sender->srtp_ctx, policy);
157 }
158
159 rtp_sender_t
rtp_sender_alloc()160 rtp_sender_alloc() {
161 return (rtp_sender_t)malloc(sizeof(rtp_sender_ctx_t));
162 }
163
164 rtp_receiver_t
rtp_receiver_alloc()165 rtp_receiver_alloc() {
166 return (rtp_receiver_t)malloc(sizeof(rtp_receiver_ctx_t));
167 }
168