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 s1, s2, opt, n, on = 1; 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 s1 = socket(AF_INET, SOCK_DGRAM, 0); 66 if (s1 < 0) 67 err(2, "socket 1 failed"); 68 69 if (setsockopt(s1, SOL_SOCKET, SO_REUSEPORT, &on, sizeof(on)) < 0) 70 err(2, "setsockopt 1 SO_REUSEPORT failed"); 71 72 if (bind(s1, (const struct sockaddr *)&local_in, sizeof(local_in)) < 0) 73 err(2, "bind 1 failed"); 74 75 if (connect(s1, (const struct sockaddr *)&in, sizeof(in)) < 0) 76 err(2, "connect 1 failed"); 77 78 s2 = socket(AF_INET, SOCK_DGRAM, 0); 79 if (s2 < 0) 80 err(2, "socket 2 failed"); 81 82 if (setsockopt(s2, SOL_SOCKET, SO_REUSEPORT, &on, sizeof(on)) < 0) 83 err(2, "setsockopt 2 SO_REUSEPORT failed"); 84 85 if (bind(s2, (const struct sockaddr *)&local_in, sizeof(local_in)) < 0) 86 err(2, "bind 2 failed"); 87 88 if (connect(s2, (const struct sockaddr *)&in, sizeof(in)) == 0) 89 errx(2, "connect 2 succeeded"); 90 91 close(s1); 92 93 n = sendto(s2, buf, sizeof(buf), 0, 94 (const struct sockaddr *)&in, sizeof(in)); 95 if (n < 0) 96 err(2, "sendto failed"); 97 else if (n != (int)sizeof(buf)) 98 errx(2, "sent truncated data %d", n); 99 100 n = read(s2, buf, sizeof(buf)); 101 if (n < 0) 102 err(2, "read failed"); 103 printf("read %d, done\n", n); 104 105 exit(0); 106 } 107