1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 1999 Brian Somers <brian@Awfulhak.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 #include <sys/param.h> 31 #include <sys/socket.h> 32 33 #include <netdb.h> 34 #include <netinet/in.h> 35 #include <arpa/inet.h> 36 37 #include <stdio.h> 38 #include <string.h> 39 40 #include "libutil.h" 41 42 struct sockinet { 43 u_char si_len; 44 u_char si_family; 45 u_short si_port; 46 }; 47 48 int 49 realhostname(char *host, size_t hsize, const struct in_addr *ip) 50 { 51 char trimmed[MAXHOSTNAMELEN]; 52 int result; 53 struct hostent *hp; 54 55 result = HOSTNAME_INVALIDADDR; 56 hp = gethostbyaddr((const char *)ip, sizeof(*ip), AF_INET); 57 58 if (hp != NULL) { 59 strlcpy(trimmed, hp->h_name, sizeof(trimmed)); 60 trimdomain(trimmed, strlen(trimmed)); 61 if (strlen(trimmed) <= hsize) { 62 char lookup[MAXHOSTNAMELEN]; 63 64 strlcpy(lookup, hp->h_name, sizeof(lookup)); 65 hp = gethostbyname(lookup); 66 if (hp == NULL) 67 result = HOSTNAME_INVALIDNAME; 68 else for (; ; hp->h_addr_list++) { 69 if (*hp->h_addr_list == NULL) { 70 result = HOSTNAME_INCORRECTNAME; 71 break; 72 } 73 if (!memcmp(*hp->h_addr_list, ip, sizeof(*ip))) { 74 strncpy(host, trimmed, hsize); 75 return HOSTNAME_FOUND; 76 } 77 } 78 } 79 } 80 81 strncpy(host, inet_ntoa(*ip), hsize); 82 83 return result; 84 } 85 86 /* 87 * struct sockaddr has very lax alignment requirements, since all its 88 * members are char or equivalent. This is a problem when trying to 89 * dereference a struct sockaddr_in6 * that was passed in as a struct 90 * sockaddr *. Although we know (or trust) that the passed-in struct was 91 * properly aligned, the compiler doesn't, and (rightly) complains. These 92 * macros perform the cast in a way that the compiler will accept. 93 */ 94 #define SOCKADDR_IN6(p) ((struct sockaddr_in6 *)(void *)(p)) 95 #define SOCKADDR_IN(p) ((struct sockaddr_in *)(void *)(p)) 96 #define SOCKINET(p) ((struct sockinet *)(void *)(p)) 97 98 int 99 realhostname_sa(char *host, size_t hsize, struct sockaddr *addr, int addrlen) 100 { 101 int result, error; 102 char buf[NI_MAXHOST]; 103 #ifdef INET6 104 struct sockaddr_in lsin; 105 #endif 106 107 result = HOSTNAME_INVALIDADDR; 108 109 #ifdef INET6 110 /* IPv4 mapped IPv6 addr consideraton, specified in rfc2373. */ 111 if (addr->sa_family == AF_INET6 && 112 addrlen == sizeof(struct sockaddr_in6) && 113 IN6_IS_ADDR_V4MAPPED(&SOCKADDR_IN6(addr)->sin6_addr)) { 114 struct sockaddr_in6 *sin6; 115 116 sin6 = SOCKADDR_IN6(addr); 117 118 memset(&lsin, 0, sizeof(lsin)); 119 lsin.sin_len = sizeof(struct sockaddr_in); 120 lsin.sin_family = AF_INET; 121 lsin.sin_port = sin6->sin6_port; 122 memcpy(&lsin.sin_addr, &sin6->sin6_addr.s6_addr[12], 123 sizeof(struct in_addr)); 124 addr = (struct sockaddr *)&lsin; 125 addrlen = lsin.sin_len; 126 } 127 #endif 128 129 error = getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0, 130 NI_NAMEREQD); 131 if (error == 0) { 132 struct addrinfo hints, *res, *ores; 133 struct sockaddr *sa; 134 135 memset(&hints, 0, sizeof(struct addrinfo)); 136 hints.ai_family = addr->sa_family; 137 hints.ai_flags = AI_CANONNAME | AI_PASSIVE; 138 hints.ai_socktype = SOCK_STREAM; 139 140 error = getaddrinfo(buf, NULL, &hints, &res); 141 if (error) { 142 result = HOSTNAME_INVALIDNAME; 143 goto numeric; 144 } 145 for (ores = res; ; res = res->ai_next) { 146 if (res == NULL) { 147 freeaddrinfo(ores); 148 result = HOSTNAME_INCORRECTNAME; 149 goto numeric; 150 } 151 sa = res->ai_addr; 152 if (sa == NULL) { 153 freeaddrinfo(ores); 154 result = HOSTNAME_INCORRECTNAME; 155 goto numeric; 156 } 157 if (sa->sa_len == addrlen && 158 sa->sa_family == addr->sa_family) { 159 SOCKINET(sa)->si_port = SOCKINET(addr)->si_port; 160 #ifdef INET6 161 /* 162 * XXX: sin6_socpe_id may not been 163 * filled by DNS 164 */ 165 if (sa->sa_family == AF_INET6 && 166 SOCKADDR_IN6(sa)->sin6_scope_id == 0) 167 SOCKADDR_IN6(sa)->sin6_scope_id = 168 SOCKADDR_IN6(addr)->sin6_scope_id; 169 #endif 170 if (!memcmp(sa, addr, sa->sa_len)) { 171 result = HOSTNAME_FOUND; 172 if (ores->ai_canonname == NULL) { 173 freeaddrinfo(ores); 174 goto numeric; 175 } 176 strlcpy(buf, ores->ai_canonname, 177 sizeof(buf)); 178 trimdomain(buf, hsize); 179 if (strlen(buf) > hsize && 180 addr->sa_family == AF_INET) { 181 freeaddrinfo(ores); 182 goto numeric; 183 } 184 strncpy(host, buf, hsize); 185 break; 186 } 187 } 188 } 189 freeaddrinfo(ores); 190 } else { 191 numeric: 192 if (getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0, 193 NI_NUMERICHOST) == 0) 194 strncpy(host, buf, hsize); 195 } 196 197 return result; 198 } 199 200 201