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  */
  28
  29 #include <sys/param.h>
  30
  31 #include <sys/socket.h>
  32 #include <netdb.h>
  33 #include <netinet/in.h>
  34 #include <arpa/inet.h>
  35
  36 #include <stdio.h>
  37 #include <string.h>
  38
  39 #include "libutil.h"
  40
  41 /* wrapper for KAME-special getnameinfo() */
  42 #ifndef NI_WITHSCOPEID
  43 #define NI_WITHSCOPEID  0
  44 #endif
  45
  46 struct sockinet {
  47         u_char  si_len;
  48         u_char  si_family;
  49         u_short si_port;
  50 };
  51
  52 int
  53 realhostname(char *host, size_t hsize, const struct in_addr *ip)
  54 {
  55         char trimmed[MAXHOSTNAMELEN];
  56         int result;
  57         struct hostent *hp;
  58
  59         result = HOSTNAME_INVALIDADDR;
  60         hp = gethostbyaddr((char *)ip, sizeof(*ip), AF_INET);
  61
  62         if (hp != NULL) {
  63                 strlcpy(trimmed, hp->h_name, sizeof(trimmed));
  64                 trimdomain(trimmed, strlen(trimmed));
  65                 if (strlen(trimmed) <= hsize) {
  66                         char lookup[MAXHOSTNAMELEN];
  67
  68                         strncpy(lookup, hp->h_name, sizeof(lookup) - 1);
  69                         lookup[sizeof(lookup) - 1] = '\0';
  70                         hp = gethostbyname(lookup);
  71                         if (hp == NULL)
  72                                 result = HOSTNAME_INVALIDNAME;
  73                         else for (; ; hp->h_addr_list++) {
  74                                 if (*hp->h_addr_list == NULL) {
  75                                         result = HOSTNAME_INCORRECTNAME;
  76                                         break;
  77                                 }
  78                                 if (!memcmp(*hp->h_addr_list, ip, sizeof(*ip))) {
  79                                         strncpy(host, trimmed, hsize);
  80                                         return HOSTNAME_FOUND;
  81                                 }
  82                         }
  83                 }
  84         }
  85
  86         strncpy(host, inet_ntoa(*ip), hsize);
  87
  88         return result;
  89 }
  90
  91 int
  92 realhostname_sa(char *host, size_t hsize, struct sockaddr *addr, int addrlen)
  93 {
  94         int result, error;
  95         char buf[NI_MAXHOST];
  96         struct sockaddr_in sin;
  97
  98         result = HOSTNAME_INVALIDADDR;
  99
 100 #ifdef INET6
 101         /* IPv4 mapped IPv6 addr consideraton, specified in rfc2373. */
 102         if (addr->sa_family == AF_INET6 &&
 103             addrlen == sizeof(struct sockaddr_in6) &&
 104             IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)addr)->sin6_addr)) {
 105                 struct sockaddr_in6 *sin6;
 106
 107                 sin6 = (struct sockaddr_in6 *)addr;
 108
 109                 memset(&sin, 0, sizeof(sin));
 110                 sin.sin_len = sizeof(struct sockaddr_in);
 111                 sin.sin_family = AF_INET;
 112                 sin.sin_port = sin6->sin6_port;
 113                 memcpy(&sin.sin_addr, &sin6->sin6_addr.s6_addr[12],
 114                        sizeof(struct in_addr));
 115                 addr = (struct sockaddr *)&sin;
 116                 addrlen = sin.sin_len;
 117         }
 118 #endif
 119
 120         error = getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
 121                             NI_WITHSCOPEID | NI_NAMEREQD);
 122         if (error == 0) {
 123                 struct addrinfo hints, *res, *ores;
 124                 struct sockaddr *sa;
 125
 126                 memset(&hints, 0, sizeof(struct addrinfo));
 127                 hints.ai_family = addr->sa_family;
 128                 hints.ai_flags = AI_CANONNAME | AI_PASSIVE;
 129                 hints.ai_socktype = SOCK_STREAM;
 130
 131                 error = getaddrinfo(buf, NULL, &hints, &res);
 132                 if (error) {
 133                         result = HOSTNAME_INVALIDNAME;
 134                         goto numeric;
 135                 }
 136                 for (ores = res; ; res = res->ai_next) {
 137                         if (res == NULL) {
 138                                 freeaddrinfo(ores);
 139                                 result = HOSTNAME_INCORRECTNAME;
 140                                 goto numeric;
 141                         }
 142                         sa = res->ai_addr;
 143                         if (sa == NULL) {
 144                                 freeaddrinfo(ores);
 145                                 result = HOSTNAME_INCORRECTNAME;
 146                                 goto numeric;
 147                         }
 148                         if (sa->sa_len == addrlen &&
 149                             sa->sa_family == addr->sa_family) {
 150                                 ((struct sockinet *)sa)->si_port = ((struct sockinet *)addr)->si_port;
 151 #ifdef INET6
 152                                 /*
 153                                  * XXX: sin6_socpe_id may not been
 154                                  * filled by DNS
 155                                  */
 156                                 if (sa->sa_family == AF_INET6 &&
 157                                     ((struct sockaddr_in6 *)sa)->sin6_scope_id == 0)
 158                                         ((struct sockaddr_in6 *)sa)->sin6_scope_id = ((struct sockaddr_in6 *)addr)->sin6_scope_id;
 159 #endif
 160                                 if (!memcmp(sa, addr, sa->sa_len)) {
 161                                         result = HOSTNAME_FOUND;
 162                                         if (ores->ai_canonname == NULL) {
 163                                                 freeaddrinfo(ores);
 164                                                 goto numeric;
 165                                         }
 166                                         strlcpy(buf, ores->ai_canonname,
 167                                                 sizeof(buf));
 168                                         trimdomain(buf, hsize);
 169                                         if (strlen(buf) > hsize &&
 170                                             addr->sa_family == AF_INET) {
 171                                                 freeaddrinfo(ores);
 172                                                 goto numeric;
 173                                         }
 174                                         strncpy(host, buf, hsize);
 175                                         break;
 176                                 }
 177                         }
 178                 }
 179                 freeaddrinfo(ores);
 180         } else {
 181     numeric:
 182                 if (getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
 183                                 NI_NUMERICHOST|NI_WITHSCOPEID) == 0)
 184                         strncpy(host, buf, hsize);
 185         }
 186
 187         return result;
 188 }
 189
 190