getnameinfo.c revision 1.2
1 /* $NetBSD: getnameinfo.c,v 1.2 2025/01/27 19:12:11 wiz Exp $ */ 2 3 /* 4 * Copyright (c) 2025 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Attaullah Ansari. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in 17 * the documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 22 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR 23 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 24 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 25 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 26 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 27 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 28 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 29 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 #ifndef lint 34 __RCSID("$NetBSD: getnameinfo.c,v 1.2 2025/01/27 19:12:11 wiz Exp $"); 35 #endif 36 37 #include <sys/types.h> 38 #include <sys/socket.h> 39 #include <netinet/in.h> 40 #include <arpa/inet.h> 41 42 #include <assert.h> 43 #include <err.h> 44 #include <errno.h> 45 #include <netdb.h> 46 #include <stdlib.h> 47 #include <stdbool.h> 48 #include <stdio.h> 49 #include <string.h> 50 #include <unistd.h> 51 52 /* 53 * getnameinfo: Resolve IP addresses and ports to hostnames and service names, 54 * similar to the getnameinfo function in the standard library. 55 * 56 * usage: 57 * getnameinfo [-46fHNnrSu] [-p port] <IP-address> 58 * 59 * -4: Restrict lookup to IPv4 addresses only 60 * -6: Restrict lookup to IPv6 addresses only 61 * -f: Suppress the fully-qualified domain name (FQDN) 62 * -H: Display only the hostname, omitting the service name 63 * -N: Display the numeric service name instead of the service name 64 * -n: Display the numeric host address instead of the hostname 65 * -p: Specify the port number to be used in the lookup 66 * -r: Ensure that the name is returned (error if no name is found) 67 * -S: Display only the service name, omitting the hostname 68 * -u: Use UDP instead of the default TCP 69 */ 70 71 72 static void usage(void) __dead; 73 static void print_result(int, int, char *, char *); 74 static in_port_t get_port(const char *); 75 static uint8_t get_family(const char *); 76 77 int 78 main(int argc, char **argv) 79 { 80 int hostlen = NI_MAXHOST, servlen = NI_MAXSERV; 81 char hostname[hostlen], service[servlen]; 82 bool hostname_only = false, service_only = false; 83 int family = AF_UNSPEC; 84 int flags = 0; 85 char *address = NULL; 86 in_port_t port = 0; 87 struct sockaddr_storage addr_st; 88 struct sockaddr_in *addr_in; 89 struct sockaddr_in6 *addr_in6; 90 int addr_stlen; 91 int ch; 92 int error; 93 94 setprogname(argv[0]); 95 96 while ((ch = getopt(argc, argv, "46rufnNHSp:")) != -1) { 97 switch (ch) { 98 case '4': 99 if (family != AF_UNSPEC) 100 goto opt46; 101 family = AF_INET; 102 break; 103 case '6': 104 if (family != AF_UNSPEC) 105 goto opt46; 106 family = AF_INET6; 107 break; 108 case 'r': 109 flags |= NI_NAMEREQD; 110 break; 111 case 'u': 112 flags |= NI_DGRAM; 113 break; 114 case 'f': 115 flags |= NI_NOFQDN; 116 break; 117 case 'n': 118 flags |= NI_NUMERICHOST; 119 break; 120 case 'N': 121 flags |= NI_NUMERICSERV; 122 break; 123 case 'H': 124 if (service_only) 125 goto optHS; 126 hostname_only = true; 127 break; 128 case 'S': 129 if (hostname_only) 130 goto optHS; 131 service_only = true; 132 break; 133 case 'p': 134 port = get_port(optarg); 135 break; 136 case '?': 137 default: 138 usage(); 139 } 140 } 141 142 argc -= optind; 143 argv += optind; 144 145 if (argc > 1) { 146 warnx("Too many addresses"); 147 usage(); 148 } 149 150 if (argc == 0 && (hostname_only || 151 (hostname_only == 0 && service_only == 0))) { 152 warnx("No IP address provided"); 153 usage(); 154 } 155 156 if (port == 0 && (service_only || 157 (hostname_only == 0 && service_only == 0))) { 158 warnx("No port number provided"); 159 usage(); 160 } 161 162 if (argc == 1) { 163 address = argv[0]; 164 if (family == AF_UNSPEC) 165 family = get_family(address); 166 } 167 168 switch (family) { 169 case AF_INET: 170 addr_in = (struct sockaddr_in *)&addr_st; 171 addr_in->sin_family = family; 172 addr_in->sin_port = htons(port); 173 if (inet_pton(family, address, &addr_in->sin_addr) == 0) { 174 warnx("Invalid IPv4 address: %s", address); 175 return EXIT_FAILURE; 176 } 177 addr_stlen = sizeof(struct sockaddr_in); 178 break; 179 case AF_INET6: 180 addr_in6 = (struct sockaddr_in6 *)&addr_st; 181 addr_in6->sin6_family = family; 182 addr_in6->sin6_port = htons(port); 183 if (inet_pton(family, address, &addr_in6->sin6_addr) == 0) { 184 warnx("Invalid IPv6 address: %s", address); 185 return EXIT_FAILURE; 186 } 187 addr_stlen = sizeof(struct sockaddr_in6); 188 break; 189 default: 190 warnx("Unsupported family %d", family); 191 return EXIT_FAILURE; 192 } 193 194 if (hostname_only) 195 servlen = 0; 196 else if (service_only) 197 hostlen = 0; 198 199 error = getnameinfo((struct sockaddr *)&addr_st, addr_stlen, 200 hostname, hostlen, service, servlen, flags); 201 if (error) 202 errx(EXIT_FAILURE, "%s", gai_strerror(error)); 203 204 print_result(hostname_only, service_only, hostname, service); 205 206 return EXIT_SUCCESS; 207 opt46: 208 warnx("Options -4 and -6 cannot be used together"); 209 usage(); 210 optHS: 211 warnx("Options -H and -S cannot be used together"); 212 usage(); 213 } 214 215 static uint8_t 216 get_family(const char* address) 217 { 218 struct in_addr ipv4_addr; 219 struct in6_addr ipv6_addr; 220 221 if (inet_pton(AF_INET, address, &ipv4_addr) == 1) 222 return AF_INET; 223 224 if (inet_pton(AF_INET6, address, &ipv6_addr) == 1) 225 return AF_INET6; 226 227 errx(EXIT_FAILURE, "Invalid addrsss %s", address); 228 } 229 230 static in_port_t 231 get_port(const char *port_str) 232 { 233 int r; 234 intmax_t port = strtoi(port_str, NULL, 0, 0, 65535, &r); 235 if (r) 236 errc(EXIT_FAILURE, r, "Invalid port number %s", port_str); 237 238 return (in_port_t)port; 239 } 240 241 static void 242 print_result(int hostname_only, int service_only, char *hostname, char *service) 243 { 244 int n; 245 if (hostname_only) 246 n = printf("%s\n", hostname); 247 else if (service_only) 248 n = printf("%s\n", service); 249 else 250 n = printf("%s %s\n", hostname, service); 251 if (n < 0) 252 err(EXIT_FAILURE, "printf"); 253 } 254 255 256 static void __dead 257 usage(void) 258 { 259 (void)fprintf(stderr, "Usage: %s", getprogname()); 260 (void)fprintf(stderr, " [-46fHNnrSu] [-p port] <IP-address>\n"); 261 exit(EXIT_FAILURE); 262 } 263
Indexes created Thu Sep 25 16:09:42 GMT 2025