1/*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 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__FBSDID("$FreeBSD$"); 31 32#include <sys/param.h> 33#include <sys/socket.h> 34 35#include <netdb.h> 36#include <netinet/in.h> 37#include <arpa/inet.h> 38 39#include <stdio.h> 40#include <string.h> 41 42#include "libutil.h" 43 44struct sockinet { 45 u_char si_len; 46 u_char si_family; 47 u_short si_port; 48}; 49 50int 51realhostname(char *host, size_t hsize, const struct in_addr *ip) 52{ 53 char trimmed[MAXHOSTNAMELEN]; 54 int result; 55 struct hostent *hp; 56 57 result = HOSTNAME_INVALIDADDR; 58 hp = gethostbyaddr((const char *)ip, sizeof(*ip), AF_INET); 59 60 if (hp != NULL) { 61 strlcpy(trimmed, hp->h_name, sizeof(trimmed)); 62 trimdomain(trimmed, strlen(trimmed)); 63 if (strlen(trimmed) <= hsize) { 64 char lookup[MAXHOSTNAMELEN]; 65 66 strlcpy(lookup, hp->h_name, sizeof(lookup)); 67 hp = gethostbyname(lookup); 68 if (hp == NULL) 69 result = HOSTNAME_INVALIDNAME; 70 else for (; ; hp->h_addr_list++) { 71 if (*hp->h_addr_list == NULL) { 72 result = HOSTNAME_INCORRECTNAME; 73 break; 74 } 75 if (!memcmp(*hp->h_addr_list, ip, sizeof(*ip))) { 76 strncpy(host, trimmed, hsize); 77 return HOSTNAME_FOUND; 78 } 79 } 80 } 81 } 82 83 strncpy(host, inet_ntoa(*ip), hsize); 84 85 return result; 86} 87 88/* 89 * struct sockaddr has very lax alignment requirements, since all its 90 * members are char or equivalent. This is a problem when trying to 91 * dereference a struct sockaddr_in6 * that was passed in as a struct 92 * sockaddr *. Although we know (or trust) that the passed-in struct was 93 * properly aligned, the compiler doesn't, and (rightly) complains. These 94 * macros perform the cast in a way that the compiler will accept. 95 */ 96#define SOCKADDR_IN6(p) ((struct sockaddr_in6 *)(void *)(p)) 97#define SOCKADDR_IN(p) ((struct sockaddr_in *)(void *)(p)) 98#define SOCKINET(p) ((struct sockinet *)(void *)(p)) 99 100int 101realhostname_sa(char *host, size_t hsize, struct sockaddr *addr, int addrlen) 102{ 103 int result, error; 104 char buf[NI_MAXHOST]; 105#ifdef INET6 106 struct sockaddr_in lsin; 107#endif 108 109 result = HOSTNAME_INVALIDADDR; 110 111#ifdef INET6 112 /* IPv4 mapped IPv6 addr consideraton, specified in rfc2373. */ 113 if (addr->sa_family == AF_INET6 && 114 addrlen == sizeof(struct sockaddr_in6) && 115 IN6_IS_ADDR_V4MAPPED(&SOCKADDR_IN6(addr)->sin6_addr)) { 116 struct sockaddr_in6 *sin6; 117 118 sin6 = SOCKADDR_IN6(addr); 119 120 memset(&lsin, 0, sizeof(lsin)); 121 lsin.sin_len = sizeof(struct sockaddr_in); 122 lsin.sin_family = AF_INET; 123 lsin.sin_port = sin6->sin6_port; 124 memcpy(&lsin.sin_addr, &sin6->sin6_addr.s6_addr[12], 125 sizeof(struct in_addr)); 126 addr = (struct sockaddr *)&lsin; 127 addrlen = lsin.sin_len; 128 } 129#endif 130 131 error = getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0, 132 NI_NAMEREQD); 133 if (error == 0) { 134 struct addrinfo hints, *res, *ores; 135 struct sockaddr *sa; 136 137 memset(&hints, 0, sizeof(struct addrinfo)); 138 hints.ai_family = addr->sa_family; 139 hints.ai_flags = AI_CANONNAME | AI_PASSIVE; 140 hints.ai_socktype = SOCK_STREAM; 141 142 error = getaddrinfo(buf, NULL, &hints, &res); 143 if (error) { 144 result = HOSTNAME_INVALIDNAME; 145 goto numeric; 146 } 147 for (ores = res; ; res = res->ai_next) { 148 if (res == NULL) { 149 freeaddrinfo(ores); 150 result = HOSTNAME_INCORRECTNAME; 151 goto numeric; 152 } 153 sa = res->ai_addr; 154 if (sa == NULL) { 155 freeaddrinfo(ores); 156 result = HOSTNAME_INCORRECTNAME; 157 goto numeric; 158 } 159 if (sa->sa_len == addrlen && 160 sa->sa_family == addr->sa_family) { 161 SOCKINET(sa)->si_port = SOCKINET(addr)->si_port; 162#ifdef INET6 163 /* 164 * XXX: sin6_socpe_id may not been 165 * filled by DNS 166 */ 167 if (sa->sa_family == AF_INET6 && 168 SOCKADDR_IN6(sa)->sin6_scope_id == 0) 169 SOCKADDR_IN6(sa)->sin6_scope_id = 170 SOCKADDR_IN6(addr)->sin6_scope_id; 171#endif 172 if (!memcmp(sa, addr, sa->sa_len)) { 173 result = HOSTNAME_FOUND; 174 if (ores->ai_canonname == NULL) { 175 freeaddrinfo(ores); 176 goto numeric; 177 } 178 strlcpy(buf, ores->ai_canonname, 179 sizeof(buf)); 180 trimdomain(buf, hsize); 181 if (strlen(buf) > hsize && 182 addr->sa_family == AF_INET) { 183 freeaddrinfo(ores); 184 goto numeric; 185 } 186 strncpy(host, buf, hsize); 187 break; 188 } 189 } 190 } 191 freeaddrinfo(ores); 192 } else { 193 numeric: 194 if (getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0, 195 NI_NUMERICHOST) == 0) 196 strncpy(host, buf, hsize); 197 } 198 199 return result; 200} 201 202 203