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\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; 26 uint8_t buf[18]; 27 28 memset(&in, 0, sizeof(in)); 29 in.sin_family = AF_INET; 30 31 while ((opt = getopt(argc, argv, "4:p:")) != -1) { 32 switch (opt) { 33 case '4': 34 if (inet_pton(AF_INET, optarg, &in.sin_addr) <= 0) 35 usage(argv[0]); 36 break; 37 38 case 'p': 39 in.sin_port = strtol(optarg, NULL, 10); 40 in.sin_port = htons(in.sin_port); 41 break; 42 43 default: 44 usage(argv[0]); 45 } 46 } 47 48 if (in.sin_addr.s_addr == INADDR_ANY || in.sin_port == 0) 49 usage(argv[0]); 50 51 s = socket(AF_INET, SOCK_DGRAM, 0); 52 if (s < 0) 53 err(2, "socket failed"); 54 55 if (connect(s, (const struct sockaddr *)&in, sizeof(in)) < 0) 56 err(2, "connect failed"); 57 58 n = write(s, buf, sizeof(buf)); 59 if (n < 0) 60 err(2, "write failed"); 61 else if (n != (int)sizeof(buf)) 62 errx(2, "written truncated data %d", n); 63 64 n = read(s, buf, sizeof(buf)); 65 if (n < 0) 66 err(2, "read failed"); 67 printf("read %d, done\n", n); 68 69 exit(0); 70 } 71