1 #include <sys/types.h> 2 #include <sys/socket.h> 3 4 #include <arpa/inet.h> 5 #include <netinet/in.h> 6 7 #include <err.h> 8 #include <stdint.h> 9 #include <stdio.h> 10 #include <stdlib.h> 11 #include <string.h> 12 #include <unistd.h> 13 14 static void 15 usage(const char *cmd) 16 { 17 fprintf(stderr, "%s -m addr -p port -i addr [-a]\n", cmd); 18 exit(1); 19 } 20 21 static int 22 create_sock(const struct sockaddr_in *in0, const struct in_addr *iface, 23 int bind_any) 24 { 25 struct ip_mreq mreq; 26 struct sockaddr_in in; 27 int s, on; 28 29 s = socket(AF_INET, SOCK_DGRAM, 0); 30 if (s < 0) 31 err(2, "socket failed"); 32 33 on = 1; 34 if (setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &on, sizeof(on)) < 0) 35 err(2, "setsockopt SO_REUSEPORT failed"); 36 37 in = *in0; 38 if (bind_any) 39 in.sin_addr.s_addr = htonl(INADDR_ANY); 40 41 if (bind(s, (const struct sockaddr *)&in, sizeof(in)) < 0) 42 err(2, "bind failed"); 43 44 memset(&mreq, 0, sizeof(mreq)); 45 mreq.imr_multiaddr = in0->sin_addr; 46 mreq.imr_interface = *iface; 47 if (setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP, 48 &mreq, sizeof(mreq)) < 0) 49 err(2, "setsockopt IP_ADD_MEMBERSHIP failed"); 50 51 return s; 52 } 53 54 int 55 main(int argc, char *argv[]) 56 { 57 struct sockaddr_in in; 58 struct in_addr iface; 59 int s1, s2, opt, n, bind_any; 60 uint8_t buf[18]; 61 62 memset(&in, 0, sizeof(in)); 63 in.sin_family = AF_INET; 64 65 memset(&iface, 0, sizeof(iface)); 66 bind_any = 0; 67 68 while ((opt = getopt(argc, argv, "ai:m:p:")) != -1) { 69 switch (opt) { 70 case 'a': 71 bind_any = 1; 72 break; 73 74 case 'i': 75 if (inet_pton(AF_INET, optarg, &iface) <= 0) 76 usage(argv[0]); 77 break; 78 79 case 'm': 80 if (inet_pton(AF_INET, optarg, &in.sin_addr) <= 0) 81 usage(argv[0]); 82 break; 83 84 case 'p': 85 in.sin_port = strtol(optarg, NULL, 10); 86 in.sin_port = htons(in.sin_port); 87 break; 88 89 default: 90 usage(argv[0]); 91 } 92 } 93 94 if (in.sin_addr.s_addr == INADDR_ANY || in.sin_port == 0 || 95 iface.s_addr == INADDR_ANY) 96 usage(argv[0]); 97 98 s1 = create_sock(&in, &iface, bind_any); 99 s2 = create_sock(&in, &iface, bind_any); 100 101 n = read(s1, buf, sizeof(buf)); 102 if (n < 0) 103 err(2, "read 1 failed"); 104 fprintf(stderr, "read 1 got %d\n", n); 105 106 n = read(s2, buf, sizeof(buf)); 107 if (n < 0) 108 err(2, "read 2 failed"); 109 fprintf(stderr, "read 2 got %d\n", n); 110 111 exit(0); 112 } 113