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 [-r]\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, reuseport; 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 reuseport = 0; 35 36 while ((opt = getopt(argc, argv, "4:P:b:p:r")) != -1) { 37 switch (opt) { 38 case '4': 39 if (inet_pton(AF_INET, optarg, &in.sin_addr) <= 0) 40 usage(argv[0]); 41 break; 42 43 case 'P': 44 local_in.sin_port = strtol(optarg, NULL, 10); 45 local_in.sin_port = htons(local_in.sin_port); 46 break; 47 48 case 'b': 49 if (inet_pton(AF_INET, optarg, &local_in.sin_addr) <= 0) 50 usage(argv[0]); 51 break; 52 53 case 'p': 54 in.sin_port = strtol(optarg, NULL, 10); 55 in.sin_port = htons(in.sin_port); 56 break; 57 58 case 'r': 59 reuseport = 1; 60 break; 61 62 default: 63 usage(argv[0]); 64 } 65 } 66 67 if (in.sin_addr.s_addr == INADDR_ANY || in.sin_port == 0 || 68 local_in.sin_port == 0) 69 usage(argv[0]); 70 71 s = socket(AF_INET, SOCK_DGRAM, 0); 72 if (s < 0) 73 err(2, "socket failed"); 74 75 if (reuseport) { 76 if (setsockopt(s, SOL_SOCKET, SO_REUSEPORT, 77 &reuseport, sizeof(reuseport)) < 0) 78 err(2, "setsockopt SO_REUSEPORT failed"); 79 } 80 81 if (bind(s, (const struct sockaddr *)&local_in, sizeof(local_in)) < 0) 82 err(2, "bind failed"); 83 84 if (connect(s, (const struct sockaddr *)&in, sizeof(in)) < 0) 85 err(2, "connect failed"); 86 87 n = write(s, buf, sizeof(buf)); 88 if (n < 0) 89 err(2, "write failed"); 90 else if (n != (int)sizeof(buf)) 91 errx(2, "written truncated data %d", n); 92 93 n = read(s, buf, sizeof(buf)); 94 if (n < 0) 95 err(2, "read failed"); 96 printf("read %d, done\n", n); 97 98 exit(0); 99 } 100