lib/libutil/realhostname.c

   1 /*-
   2  * Copyright (c) 1999 Brian Somers <brian@Awfulhak.org>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD: src/lib/libutil/realhostname.c,v 1.6.2.6 2002/06/29 18:26:37 ume Exp $
  27  * $DragonFly: src/lib/libutil/realhostname.c,v 1.2 2003/06/17 04:26:52 dillon Exp $
  28  */
  29
  30 #include <sys/param.h>
  31
  32 #include <sys/socket.h>
  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 /* wrapper for KAME-special getnameinfo() */
  43 #ifndef NI_WITHSCOPEID
  44 #define NI_WITHSCOPEID  0
  45 #endif
  46
  47 struct sockinet {
  48         u_char  si_len;
  49         u_char  si_family;
  50         u_short si_port;
  51 };
  52
  53 int
  54 realhostname(char *host, size_t hsize, const struct in_addr *ip)
  55 {
  56         char trimmed[MAXHOSTNAMELEN];
  57         int result;
  58         struct hostent *hp;
  59
  60         result = HOSTNAME_INVALIDADDR;
  61         hp = gethostbyaddr(ip, sizeof(*ip), AF_INET);
  62
  63         if (hp != NULL) {
  64                 strlcpy(trimmed, hp->h_name, sizeof(trimmed));
  65                 trimdomain(trimmed, strlen(trimmed));
  66                 if (strlen(trimmed) <= hsize) {
  67                         char lookup[MAXHOSTNAMELEN];
  68
  69                         strncpy(lookup, hp->h_name, sizeof(lookup) - 1);
  70                         lookup[sizeof(lookup) - 1] = '\0';
  71                         hp = gethostbyname(lookup);
  72                         if (hp == NULL)
  73                                 result = HOSTNAME_INVALIDNAME;
  74                         else for (; ; hp->h_addr_list++) {
  75                                 if (*hp->h_addr_list == NULL) {
  76                                         result = HOSTNAME_INCORRECTNAME;
  77                                         break;
  78                                 }
  79                                 if (!memcmp(*hp->h_addr_list, ip, sizeof(*ip))) {
  80                                         strncpy(host, trimmed, hsize);
  81                                         return HOSTNAME_FOUND;
  82                                 }
  83                         }
  84                 }
  85         }
  86
  87         strncpy(host, inet_ntoa(*ip), hsize);
  88
  89         return result;
  90 }
  91
  92 int
  93 realhostname_sa(char *host, size_t hsize, struct sockaddr *addr, int addrlen)
  94 {
  95         int result, error;
  96         char buf[NI_MAXHOST];
  97         struct sockaddr_in sin;
  98
  99         result = HOSTNAME_INVALIDADDR;
 100
 101 #ifdef INET6
 102         /* IPv4 mapped IPv6 addr consideraton, specified in rfc2373. */
 103         if (addr->sa_family == AF_INET6 &&
 104             addrlen == sizeof(struct sockaddr_in6) &&
 105             IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)addr)->sin6_addr)) {
 106                 struct sockaddr_in6 *sin6;
 107
 108                 sin6 = (struct sockaddr_in6 *)addr;
 109
 110                 memset(&sin, 0, sizeof(sin));
 111                 sin.sin_len = sizeof(struct sockaddr_in);
 112                 sin.sin_family = AF_INET;
 113                 sin.sin_port = sin6->sin6_port;
 114                 memcpy(&sin.sin_addr, &sin6->sin6_addr.s6_addr[12],
 115                        sizeof(struct in_addr));
 116                 addr = (struct sockaddr *)&sin;
 117                 addrlen = sin.sin_len;
 118         }
 119 #endif
 120
 121         error = getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
 122                             NI_WITHSCOPEID | NI_NAMEREQD);
 123         if (error == 0) {
 124                 struct addrinfo hints, *res, *ores;
 125                 struct sockaddr *sa;
 126
 127                 memset(&hints, 0, sizeof(struct addrinfo));
 128                 hints.ai_family = addr->sa_family;
 129                 hints.ai_flags = AI_CANONNAME | AI_PASSIVE;
 130                 hints.ai_socktype = SOCK_STREAM;
 131
 132                 error = getaddrinfo(buf, NULL, &hints, &res);
 133                 if (error) {
 134                         result = HOSTNAME_INVALIDNAME;
 135                         goto numeric;
 136                 }
 137                 for (ores = res; ; res = res->ai_next) {
 138                         if (res == NULL) {
 139                                 freeaddrinfo(ores);
 140                                 result = HOSTNAME_INCORRECTNAME;
 141                                 goto numeric;
 142                         }
 143                         sa = res->ai_addr;
 144                         if (sa == NULL) {
 145                                 freeaddrinfo(ores);
 146                                 result = HOSTNAME_INCORRECTNAME;
 147                                 goto numeric;
 148                         }
 149                         if (sa->sa_len == addrlen &&
 150                             sa->sa_family == addr->sa_family) {
 151                                 ((struct sockinet *)sa)->si_port = ((struct sockinet *)addr)->si_port;
 152 #ifdef INET6
 153                                 /*
 154                                  * XXX: sin6_socpe_id may not been
 155                                  * filled by DNS
 156                                  */
 157                                 if (sa->sa_family == AF_INET6 &&
 158                                     ((struct sockaddr_in6 *)sa)->sin6_scope_id == 0)
 159                                         ((struct sockaddr_in6 *)sa)->sin6_scope_id = ((struct sockaddr_in6 *)addr)->sin6_scope_id;
 160 #endif
 161                                 if (!memcmp(sa, addr, sa->sa_len)) {
 162                                         result = HOSTNAME_FOUND;
 163                                         if (ores->ai_canonname == NULL) {
 164                                                 freeaddrinfo(ores);
 165                                                 goto numeric;
 166                                         }
 167                                         strlcpy(buf, ores->ai_canonname,
 168                                                 sizeof(buf));
 169                                         trimdomain(buf, hsize);
 170                                         if (strlen(buf) > hsize &&
 171                                             addr->sa_family == AF_INET) {
 172                                                 freeaddrinfo(ores);
 173                                                 goto numeric;
 174                                         }
 175                                         strncpy(host, buf, hsize);
 176                                         break;
 177                                 }
 178                         }
 179                 }
 180                 freeaddrinfo(ores);
 181         } else {
 182     numeric:
 183                 if (getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
 184                                 NI_NUMERICHOST|NI_WITHSCOPEID) == 0)
 185                         strncpy(host, buf, hsize);
 186         }
 187
 188         return result;
 189 }
 190
 191