1 #include <sys/types.h> 2 #include <sys/socket.h> 3 #include <netinet/in.h> 4 #include <errno.h> 5 #include <stdio.h> 6 #include <string.h> 7 #include <stdlib.h> 8 #include <unistd.h> 9 #include <netdb.h> 10 11 int main(int argc, char *argv[]) 12 { 13 int s; 14 struct in_addr simr, gimr; 15 16 unsigned i1, i2, i3, i4; 17 struct hostent *hp, *gethostbyname(); 18 19 unsigned char ttl; 20 char no_loop = 0, do_loop = 1; 21 unsigned long len = 0; 22 23 if (argc != 2) { 24 fprintf(stderr, 25 "usage: %s interface_name (or i.i.i.i)\n", argv[0]); 26 exit(1); 27 } 28 s = socket(AF_INET, SOCK_DGRAM, 0); 29 if (s == -1) { 30 perror("can't open socket"); 31 exit(1); 32 } 33 34 hp = gethostbyname(argv[1]); 35 if (hp) 36 memcpy(&simr.s_addr, hp->h_addr, hp->h_length); 37 else if (sscanf(argv[1], "%u.%u.%u.%u", &i1, &i2, &i3, &i4) != 4) { 38 fprintf(stderr, "Bad interface address\n"); 39 exit(1); 40 } else 41 simr.s_addr = htonl((i1 << 24) | (i2 << 16) | (i3 << 8) | i4); 42 43 /* verify socket options error messages */ 44 if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_IF, &simr, 45 sizeof(simr)) != 0) 46 perror("Setting IP_MULTICAST_IF"), exit(1); 47 len = sizeof(gimr); 48 if (getsockopt 49 (s, IPPROTO_IP, IP_MULTICAST_IF, &gimr, (socklen_t *)&len) != 0) 50 perror("Getting IP_MULTICAST_IF"), exit(1); 51 52 len = sizeof(ttl); 53 if (getsockopt 54 (s, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, (socklen_t *)&len) != 0) 55 perror("Getting IP_MULTICAST_TTL"), exit(1); 56 57 ttl = 10; /* Set ttl to 10 */ 58 /* printf("setting ttl=10\n");*/ 59 if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) != 0) 60 perror("Setting IP_MULTICAST_TTL"), exit(1); 61 62 if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_LOOP, &do_loop, sizeof(char)) 63 != 0) 64 perror("Setting IP_MULTICAST_LOOP"), exit(1); 65 if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_LOOP, &no_loop, sizeof(char)) 66 != 0) 67 perror("Setting IP_MULTICAST_LOOP"), exit(1); 68 len = sizeof(no_loop); 69 if (getsockopt 70 (s, IPPROTO_IP, IP_MULTICAST_LOOP, &no_loop, 71 (socklen_t *)&len) != 0) 72 perror("Getting IP_MULTICAST_LOOP"), exit(1); 73 74 close(s); 75 exit(0); 76 } 77
