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