git.zerfleddert.de Git - record-dvb/blob - sap.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <sys/types.h>
   4 #include <sys/socket.h>
   5 #include <netinet/in.h>
   6 #include <arpa/inet.h>
   7 #include <sys/time.h>
   8 #include <time.h>
   9 #include <string.h>
  10 #include <strings.h>
  11 #include <unistd.h>
  12 #include <sys/select.h>
  13
  14 #include "mcast.h"
  15 #include "sap.h"
  16
  17 #define SAP_ADDR        "224.2.127.254"
  18 #define SAP_PORT        9875
  19 #define SAP_MAX_SIZE    1024
  20
  21 #define SAP_TIMEOUT     3
  22
  23 #define BUFFSIZE        SAP_MAX_SIZE
  24
  25 struct sdp_info {
  26         char *service;
  27         char *host;
  28         char *proto;
  29         char *port;
  30 };
  31
  32 struct sdp_info *parse_sdp(char *sdp, int len)
  33 {
  34         char *pos;
  35         static struct sdp_info sdpinfo;
  36
  37         /* RFC 2327
  38          * v=0
  39          * o=- 6dca 1 IN IP4 192.168.100.17:2000
  40          * s=TV Das Erste
  41          * t=0 0
  42          * c=IN IP4 192.168.100.17/1
  43          * m=video 2000 http 33
  44          * a=tool:getstream
  45          * a=type:broadcast
  46          */
  47
  48         bzero(&sdpinfo, sizeof(struct sdp_info));
  49
  50         pos = sdp;
  51         while(*pos != 0 && (pos-sdp) < len) {
  52                 if (*pos == 0x0d)
  53                         *pos = 0;
  54
  55                 if (*pos == 0x0a) {
  56                         *pos = 0;
  57
  58                         if (!strncasecmp("s=", sdp, 2)) {
  59                                 sdpinfo.service = sdp + 2;
  60                         } else if (!strncasecmp("c=", sdp, 2)) {
  61                                 int poscnt = 0;
  62
  63                                 sdp += 2;
  64                                 while (*sdp != 0) {
  65                                         if (poscnt == 2 && *sdp == '/') {
  66                                                 *sdp = 0;
  67                                                 break;
  68                                         }
  69
  70                                         if (*sdp == ' ') {
  71                                                 *sdp = 0;
  72                                                 poscnt++;
  73
  74                                                 /* c=<network type> <address type> <connection address> */
  75                                                 if (poscnt == 2)
  76                                                         sdpinfo.host = sdp + 1;
  77
  78                                                 if (poscnt > 2)
  79                                                         break;
  80                                         }
  81                                         sdp++;
  82                                 }
  83                         } else if (!strncasecmp("m=", sdp, 2)) {
  84                                 int poscnt = 0;
  85
  86                                 sdp += 2;
  87                                 while (*sdp != 0) {
  88                                         if (*sdp == ' ') {
  89                                                 *sdp = 0;
  90                                                 poscnt++;
  91
  92                                                 /* m=<media> <port> <transport> <fmt list> */
  93                                                 if (poscnt == 1)
  94                                                         sdpinfo.port = sdp + 1;
  95
  96                                                 if (poscnt == 2)
  97                                                         sdpinfo.proto = sdp + 1;
  98
  99                                                 if (poscnt > 2)
 100                                                         break;
 101                                         }
 102                                         sdp++;
 103                                 }
 104                         }
 105
 106                         sdp = ++pos;
 107                         continue;
 108                 }
 109                 pos++;
 110         }
 111
 112         return &sdpinfo;
 113 }
 114
 115
 116 char *get_url_from_sap(char *service)
 117 {
 118         struct timeval start, curr;
 119         struct ip_mreq mreq;
 120         unsigned char buffer[BUFFSIZE];
 121         char *url = NULL;
 122         int fd;
 123
 124         snprintf(buffer,BUFFSIZE,"udp://%s:%u", SAP_ADDR, SAP_PORT);
 125
 126         fd = open_mcast(buffer);
 127
 128         gettimeofday(&start, NULL);
 129
 130         do {
 131                 int recvd;
 132                 fd_set rfds;
 133                 struct timeval tv;
 134                 int retval;
 135                 int sap_version, sap_addrtype, sap_messagetype, sap_encrypted, sap_compressed;
 136                 in_addr_t sender_address;
 137                 unsigned char auth_len;
 138                 unsigned short msgid;
 139                 unsigned char *sdp;
 140                 struct sdp_info *sdpinfo;
 141
 142                 FD_ZERO(&rfds);
 143                 FD_SET(fd, &rfds);
 144
 145                 tv.tv_sec = 0;
 146                 tv.tv_usec = 100000;
 147
 148                 if ((retval = select(fd+1, &rfds, NULL, NULL, &tv)) == -1) {
 149                         perror("select");
 150                         return NULL;
 151                 }
 152
 153                 if (!retval) {
 154                         gettimeofday(&curr, NULL);
 155                         continue;
 156                 }
 157
 158                 bzero(buffer, BUFFSIZE);
 159                 if ((recvd = recv(fd, buffer, BUFFSIZE, 0)) < 1) {
 160                         perror("recv");
 161                         return NULL;
 162                 }
 163
 164                 gettimeofday(&curr, NULL);
 165
 166                 sap_version = (buffer[0] >> 5) & 0x7;
 167                 sap_addrtype = (buffer[0] >> 4) & 0x1;
 168                 sap_messagetype = (buffer[0] >> 2) & 0x1;
 169                 sap_encrypted = (buffer[0] >> 1) & 0x1;
 170                 sap_compressed = buffer[0] & 0x1;
 171                 auth_len = buffer[1];
 172                 msgid = buffer[2] << 8 | buffer[3];
 173                 memcpy(&sender_address, buffer+4, (sap_addrtype?16:4));
 174                 sdp = buffer + 4 /* (sap_*, auth_len, msgid) */ + (sap_addrtype?16:4) + auth_len;
 175
 176 #ifdef DEBUG
 177                 printf("\n");
 178                 printf("SAP-Version: %d\n", sap_version);
 179                 printf("Adresstyp: %s\n", (sap_addrtype?"IPv6":"IPv4"));
 180                 printf("Messagetype: %s\n", (sap_messagetype?"Announcement":"Deletion"));
 181                 printf("Encrypted: %d\n", sap_encrypted);
 182                 printf("Compressed: %d\n", sap_compressed);
 183                 printf("Authentication Length: %d\n", auth_len);
 184                 printf("Sender: %u\n", sender_address);
 185                 printf("Message Identifier Hash: %u\n", msgid);
 186 #endif
 187
 188                 if (sap_addrtype)
 189                         continue; /* We don't support IPv6 for now */
 190
 191 #if 0 /* Getstream gets this wrong, see rfc2974 */
 192                 if (sap_messagetype)
 193                         continue; /* We are not interested in deletions */
 194 #endif
 195
 196                 if (sap_encrypted || sap_compressed)
 197                         continue;
 198
 199                 sdpinfo = parse_sdp(sdp, recvd-(sdp-buffer));
 200
 201                 if (sdpinfo->service && sdpinfo->proto && sdpinfo->port) {
 202                         if (!sdpinfo->host) {
 203                                  struct in_addr inaddr;
 204
 205                                  inaddr.s_addr = sender_address;
 206                                  sdpinfo->host = inet_ntoa(inaddr);
 207                         }
 208
 209 #ifdef DEBUG
 210                         printf("%s -> %s://%s:%s\n", sdpinfo->service, sdpinfo->proto, sdpinfo->host, sdpinfo->port);
 211 #endif
 212
 213                         if (strlen(service) < strlen(sdpinfo->service)) {
 214                                 sdpinfo->service += strlen(sdpinfo->service) - strlen(service);
 215                         }
 216
 217                         if (!strncasecmp(service, sdpinfo->service, strlen(service))) {
 218                                 int len = strlen(sdpinfo->host)+strlen(sdpinfo->proto)+strlen(sdpinfo->port)+5;
 219
 220                                 if (!(url = malloc(len))) {
 221                                         perror("malloc");
 222                                         return NULL;
 223                                 }
 224
 225                                 snprintf(url, len, "%s://%s:%s", sdpinfo->proto, sdpinfo->host, sdpinfo->port);
 226                                 url[len-1] = 0;
 227                                 break;
 228                         }
 229                 }
 230
 231         } while(curr.tv_sec < start.tv_sec+SAP_TIMEOUT);
 232
 233         mreq.imr_multiaddr.s_addr = inet_addr(SAP_ADDR);
 234         mreq.imr_interface.s_addr = INADDR_ANY;
 235         setsockopt (fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
 236
 237         close(fd);
 238
 239         return url;
 240 }