getnameinfo.c revision 1.3
1 /* $NetBSD: getnameinfo.c,v 1.3 2025/02/01 13:42:57 christos 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 1.3 2025/02/01 13:42:57 christos 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 socklen_t hostlen = NI_MAXHOST, servlen = NI_MAXSERV, addrlen; 81 char hostname[NI_MAXHOST], service[NI_MAXSERV]; 82 bool hostname_only = false, service_only = false; 83 uint8_t 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 ch; 91 int error; 92 93 setprogname(argv[0]); 94 95 while ((ch = getopt(argc, argv, "46rufnNHSp:")) != -1) { 96 switch (ch) { 97 case '4': 98 if (family != AF_UNSPEC) 99 goto opt46; 100 family = AF_INET; 101 break; 102 case '6': 103 if (family != AF_UNSPEC) 104 goto opt46; 105 family = AF_INET6; 106 break; 107 case 'r': 108 flags |= NI_NAMEREQD; 109 break; 110 case 'u': 111 flags |= NI_DGRAM; 112 break; 113 case 'f': 114 flags |= NI_NOFQDN; 115 break; 116 case 'n': 117 flags |= NI_NUMERICHOST; 118 break; 119 case 'N': 120 flags |= NI_NUMERICSERV; 121 break; 122 case 'H': 123 if (service_only) 124 goto optHS; 125 hostname_only = true; 126 break; 127 case 'S': 128 if (hostname_only) 129 goto optHS; 130 service_only = true; 131 break; 132 case 'p': 133 port = get_port(optarg); 134 break; 135 case '?': 136 default: 137 usage(); 138 } 139 } 140 141 argc -= optind; 142 argv += optind; 143 144 if (argc > 1) { 145 warnx("Too many addresses"); 146 usage(); 147 } 148 149 if (argc == 0 && (hostname_only || 150 (hostname_only == 0 && service_only == 0))) { 151 warnx("No IP address provided"); 152 usage(); 153 } 154 155 if (port == 0 && (service_only || 156 (hostname_only == 0 && service_only == 0))) { 157 warnx("No port number provided"); 158 usage(); 159 } 160 161 if (argc == 1) { 162 address = argv[0]; 163 if (family == AF_UNSPEC) 164 family = get_family(address); 165 } 166 167 switch (family) { 168 case AF_INET: 169 addr_in = (struct sockaddr_in *)&addr_st; 170 addr_in->sin_family = family; 171 addr_in->sin_port = htons(port); 172 if (inet_pton(family, address, &addr_in->sin_addr) == 0) { 173 warnx("Invalid IPv4 address: %s", address); 174 return EXIT_FAILURE; 175 } 176 addrlen = sizeof(*addr_in); 177 break; 178 case AF_INET6: 179 addr_in6 = (struct sockaddr_in6 *)&addr_st; 180 addr_in6->sin6_family = family; 181 addr_in6->sin6_port = htons(port); 182 if (inet_pton(family, address, &addr_in6->sin6_addr) == 0) { 183 warnx("Invalid IPv6 address: %s", address); 184 return EXIT_FAILURE; 185 } 186 addrlen = sizeof(*addr_in6); 187 break; 188 default: 189 warnx("Unsupported family %d", family); 190 return EXIT_FAILURE; 191 } 192 193 if (hostname_only) 194 servlen = 0; 195 else if (service_only) 196 hostlen = 0; 197 198 error = getnameinfo((struct sockaddr *)&addr_st, addrlen, 199 hostname, hostlen, service, servlen, flags); 200 if (error) 201 errx(EXIT_FAILURE, "%s", gai_strerror(error)); 202 203 print_result(hostname_only, service_only, hostname, service); 204 205 return EXIT_SUCCESS; 206 opt46: 207 warnx("Options -4 and -6 cannot be used together"); 208 usage(); 209 optHS: 210 warnx("Options -H and -S cannot be used together"); 211 usage(); 212 } 213 214 static uint8_t 215 get_family(const char* address) 216 { 217 struct in_addr ipv4_addr; 218 struct in6_addr ipv6_addr; 219 220 if (inet_pton(AF_INET, address, &ipv4_addr) == 1) 221 return AF_INET; 222 223 if (inet_pton(AF_INET6, address, &ipv6_addr) == 1) 224 return AF_INET6; 225 226 errx(EXIT_FAILURE, "Invalid addrsss %s", address); 227 } 228 229 static in_port_t 230 get_port(const char *port_str) 231 { 232 int r; 233 intmax_t port = strtoi(port_str, NULL, 0, 0, 65535, &r); 234 if (r) 235 errc(EXIT_FAILURE, r, "Invalid port number %s", port_str); 236 237 return (in_port_t)port; 238 } 239 240 static void 241 print_result(int hostname_only, int service_only, char *hostname, char *service) 242 { 243 int n; 244 if (hostname_only) 245 n = printf("%s\n", hostname); 246 else if (service_only) 247 n = printf("%s\n", service); 248 else 249 n = printf("%s %s\n", hostname, service); 250 if (n < 0) 251 err(EXIT_FAILURE, "printf"); 252 } 253 254 255 static void __dead 256 usage(void) 257 { 258 (void)fprintf(stderr, "Usage: %s", getprogname()); 259 (void)fprintf(stderr, " [-46fHNnrSu] [-p port] <IP-address>\n"); 260 exit(EXIT_FAILURE); 261 } 262
Indexes created Thu Sep 25 16:09:42 GMT 2025