lib/roken/getnameinfo_verified.c

   1 /*
   2  * Copyright (c) 1999 - 2002 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #ifdef HAVE_CONFIG_H
  35 #include <config.h>
  36 RCSID("$Id$");
  37 #endif
  38
  39 #include "roken.h"
  40
  41 /*
  42  * Try to obtain a verified name for the address in `sa, salen' (much
  43  * similar to getnameinfo).
  44  * Verified in this context means that forwards and backwards lookups
  45  * in DNS are consistent.  If that fails, return an error if the
  46  * NI_NAMEREQD flag is set or return the numeric address as a string.
  47  */
  48
  49 int ROKEN_LIB_FUNCTION
  50 getnameinfo_verified(const struct sockaddr *sa, socklen_t salen,
  51                      char *host, size_t hostlen,
  52                      char *serv, size_t servlen,
  53                      int flags)
  54 {
  55     int ret;
  56     struct addrinfo *ai, *a;
  57     char servbuf[NI_MAXSERV];
  58     struct addrinfo hints;
  59
  60     if (host == NULL)
  61         return EAI_NONAME;
  62
  63     if (serv == NULL) {
  64         serv = servbuf;
  65         servlen = sizeof(servbuf);
  66     }
  67
  68     ret = getnameinfo (sa, salen, host, hostlen, serv, servlen,
  69                        flags | NI_NUMERICSERV);
  70     if (ret)
  71         goto fail;
  72
  73     memset (&hints, 0, sizeof(hints));
  74     hints.ai_socktype = SOCK_STREAM;
  75     ret = getaddrinfo (host, serv, &hints, &ai);
  76     if (ret)
  77         goto fail;
  78     for (a = ai; a != NULL; a = a->ai_next) {
  79         if (a->ai_addrlen == salen
  80             && memcmp (a->ai_addr, sa, salen) == 0) {
  81             freeaddrinfo (ai);
  82             return 0;
  83         }
  84     }
  85     freeaddrinfo (ai);
  86  fail:
  87     if (flags & NI_NAMEREQD)
  88         return EAI_NONAME;
  89     ret = getnameinfo (sa, salen, host, hostlen, serv, servlen,
  90                        flags | NI_NUMERICSERV | NI_NUMERICHOST);
  91     return ret;
  92 }