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