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