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 <stdio.h> 9 #include <stdint.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 -4 ip4 -p port [-b ip4] -P bind_port\n", cmd); 18 exit(1); 19 } 20 21 int 22 main(int argc, char *argv[]) 23 { 24 struct sockaddr_in in, local_in; 25 int s, opt, n; 26 uint8_t buf[18]; 27 28 memset(&in, 0, sizeof(in)); 29 in.sin_family = AF_INET; 30 31 memset(&local_in, 0, sizeof(local_in)); 32 local_in.sin_family = AF_INET; 33 34 while ((opt = getopt(argc, argv, "4:P:b:p:")) != -1) { 35 switch (opt) { 36 case '4': 37 if (inet_pton(AF_INET, optarg, &in.sin_addr) <= 0) 38 usage(argv[0]); 39 break; 40 41 case 'P': 42 local_in.sin_port = strtol(optarg, NULL, 10); 43 local_in.sin_port = htons(local_in.sin_port); 44 break; 45 46 case 'b': 47 if (inet_pton(AF_INET, optarg, &local_in.sin_addr) <= 0) 48 usage(argv[0]); 49 break; 50 51 case 'p': 52 in.sin_port = strtol(optarg, NULL, 10); 53 in.sin_port = htons(in.sin_port); 54 break; 55 56 default: 57 usage(argv[0]); 58 } 59 } 60 61 if (in.sin_addr.s_addr == INADDR_ANY || in.sin_port == 0 || 62 local_in.sin_port == 0) 63 usage(argv[0]); 64 65 s = socket(AF_INET, SOCK_DGRAM, 0); 66 if (s < 0) 67 err(2, "socket failed"); 68 69 if (bind(s, (const struct sockaddr *)&local_in, sizeof(local_in)) < 0) 70 err(2, "bind failed"); 71 72 n = sendto(s, buf, sizeof(buf), 0, 73 (const struct sockaddr *)&in, sizeof(in)); 74 if (n < 0) 75 err(2, "sendto failed"); 76 else if (n != (int)sizeof(buf)) 77 errx(2, "sent truncated data %d", n); 78 79 n = read(s, buf, sizeof(buf)); 80 if (n < 0) 81 err(2, "read failed"); 82 printf("read %d, done\n", n); 83 84 exit(0); 85 } 86