getnameinfo.c revision 1.7
1 /* $NetBSD: getnameinfo.c,v 1.7 2025/02/05 13:10:29 riastradh 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 1.7 2025/02/05 13:10:29 riastradh Exp $"); 35 #endif 36 37 #include <sys/types.h> 38 39 #include <sys/socket.h> 40 41 #include <arpa/inet.h> 42 #include <netinet/in.h> 43 44 #include <assert.h> 45 #include <err.h> 46 #include <errno.h> 47 #include <netdb.h> 48 #include <stdbool.h> 49 #include <stdio.h> 50 #include <stdlib.h> 51 #include <string.h> 52 #include <unistd.h> 53 54 /* 55 * getnameinfo: Resolve IP addresses and ports to hostnames and service names, 56 * similar to the getnameinfo function in the standard library. 57 * 58 * usage: 59 * getnameinfo [-46fHNnrSu] [-p port] [<IP-address>] 60 * 61 * -4: Restrict lookup to IPv4 addresses only 62 * -6: Restrict lookup to IPv6 addresses only 63 * -f: Suppress the fully-qualified domain name (FQDN) 64 * -H: Display only the hostname, omitting the service name 65 * -N: Display the numeric service name instead of the service name 66 * -n: Display the numeric host address instead of the hostname 67 * -p: Specify the port number to be used in the lookup 68 * -r: Ensure that the name is returned (error if no name is found) 69 * -S: Display only the service name, omitting the hostname 70 * -u: Use UDP instead of the default TCP 71 */ 72 73 static void usage(void) __dead; 74 static void print_result(bool, bool, char *, char *); 75 static in_port_t get_port(const char *); 76 static uint8_t get_family(const char *); 77 78 int 79 main(int argc, char **argv) 80 { 81 socklen_t hostlen = NI_MAXHOST, servlen = NI_MAXSERV, addrlen; 82 char hostname[NI_MAXHOST], service[NI_MAXSERV]; 83 bool hostname_only = false, service_only = false; 84 uint8_t family = AF_UNSPEC; 85 int flags = 0; 86 char *address = NULL; 87 in_port_t port = 0; 88 struct sockaddr_storage addr_st; 89 struct sockaddr_in *addr_in; 90 struct sockaddr_in6 *addr_in6; 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 && !service_only))) { 152 warnx("No IP address provided"); 153 usage(); 154 } 155 156 if (port == 0 && (service_only || 157 (!hostname_only && !service_only))) { 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 (address == NULL) { 174 addr_in->sin_addr.s_addr = INADDR_ANY; 175 } else if (inet_pton(family, address, &addr_in->sin_addr) 176 == 0) { 177 warnx("Invalid IPv4 address: %s", address); 178 return EXIT_FAILURE; 179 } 180 addrlen = sizeof(*addr_in); 181 break; 182 case AF_INET6: 183 addr_in6 = (struct sockaddr_in6 *)&addr_st; 184 addr_in6->sin6_family = family; 185 addr_in6->sin6_port = htons(port); 186 if (address == NULL) { 187 addr_in6->sin6_addr = 188 (struct in6_addr)IN6ADDR_ANY_INIT; 189 } else if (inet_pton(family, address, &addr_in6->sin6_addr) 190 == 0) { 191 warnx("Invalid IPv6 address: %s", address); 192 return EXIT_FAILURE; 193 } 194 addrlen = sizeof(*addr_in6); 195 break; 196 default: 197 warnx("Unsupported family %d", family); 198 return EXIT_FAILURE; 199 } 200 201 if (hostname_only) 202 servlen = 0; 203 else if (service_only) 204 hostlen = 0; 205 206 error = getnameinfo((struct sockaddr *)&addr_st, addrlen, 207 hostname, hostlen, service, servlen, flags); 208 if (error) 209 errx(EXIT_FAILURE, "%s", gai_strerror(error)); 210 211 print_result(hostname_only, service_only, hostname, service); 212 fflush(stdout); 213 return ferror(stdout) ? EXIT_FAILURE : EXIT_SUCCESS; 214 opt46: 215 warnx("Options -4 and -6 cannot be used together"); 216 usage(); 217 optHS: 218 warnx("Options -H and -S cannot be used together"); 219 usage(); 220 } 221 222 static uint8_t 223 get_family(const char *address) 224 { 225 struct in_addr ipv4_addr; 226 struct in6_addr ipv6_addr; 227 228 if (inet_pton(AF_INET, address, &ipv4_addr) == 1) 229 return AF_INET; 230 231 if (inet_pton(AF_INET6, address, &ipv6_addr) == 1) 232 return AF_INET6; 233 234 errx(EXIT_FAILURE, "Invalid addrsss %s", address); 235 } 236 237 static in_port_t 238 get_port(const char *port_str) 239 { 240 int r; 241 242 const intmax_t port = strtoi(port_str, NULL, 0, 0, 65535, &r); 243 if (r) 244 errc(EXIT_FAILURE, r, "Invalid port number %s", port_str); 245 246 return (in_port_t)port; 247 } 248 249 static void 250 print_result(bool hostname_only, bool service_only, 251 char *hostname, char *service) 252 { 253 254 if (hostname_only) 255 printf("%s\n", hostname); 256 else if (service_only) 257 printf("%s\n", service); 258 else 259 printf("%s %s\n", hostname, service); 260 } 261 262 static void __dead 263 usage(void) 264 { 265 266 (void)fprintf(stderr, "Usage: %s", getprogname()); 267 (void)fprintf(stderr, " [-46fHNnrSu] [-p port] [<IP-address>]\n"); 268 exit(EXIT_FAILURE); 269 } 270
Indexes created Fri Sep 26 08:10:20 GMT 2025