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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 | } |