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      1 /*	$NetBSD: getnameinfo_verified.c,v 1.2 2017/01/28 21:31:50 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1999 - 2002 Kungliga Tekniska Hgskolan
      5  * (Royal Institute of Technology, Stockholm, Sweden).
      6  * All rights reserved.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  *
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  *
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * 3. Neither the name of the Institute nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <config.h>
     37 
     38 #include <krb5/roken.h>
     39 
     40 /*
     41  * Try to obtain a verified name for the address in `sa, salen' (much
     42  * similar to getnameinfo).
     43  * Verified in this context means that forwards and backwards lookups
     44  * in DNS are consistent.  If that fails, return an error if the
     45  * NI_NAMEREQD flag is set or return the numeric address as a string.
     46  */
     47 
     48 ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
     49 getnameinfo_verified(const struct sockaddr *sa, socklen_t salen,
     50 		     char *host, size_t hostlen,
     51 		     char *serv, size_t servlen,
     52 		     int flags)
     53 {
     54     int ret;
     55     struct addrinfo *ai, *a;
     56     char servbuf[NI_MAXSERV];
     57     struct addrinfo hints;
     58     void *saaddr;
     59     size_t sasize;
     60 
     61     if (host == NULL)
     62 	return EAI_NONAME;
     63 
     64     if (serv == NULL) {
     65 	serv = servbuf;
     66 	servlen = sizeof(servbuf);
     67     }
     68 
     69     ret = getnameinfo (sa, salen, host, hostlen, serv, servlen,
     70 		       flags | NI_NUMERICSERV);
     71     if (ret)
     72 	goto fail;
     73 
     74     memset (&hints, 0, sizeof(hints));
     75     hints.ai_socktype = SOCK_STREAM;
     76     ret = getaddrinfo (host, serv, &hints, &ai);
     77     if (ret)
     78 	goto fail;
     79 
     80     saaddr = socket_get_address(sa);
     81     sasize = socket_addr_size(sa);
     82     for (a = ai; a != NULL; a = a->ai_next) {
     83 	if (sasize == socket_addr_size(a->ai_addr) &&
     84 	    memcmp(saaddr, socket_get_address(a->ai_addr), sasize) == 0) {
     85 	    freeaddrinfo (ai);
     86 	    return 0;
     87 	}
     88     }
     89     freeaddrinfo (ai);
     90  fail:
     91     if (flags & NI_NAMEREQD)
     92 	return EAI_NONAME;
     93     ret = getnameinfo (sa, salen, host, hostlen, serv, servlen,
     94 		       flags | NI_NUMERICSERV | NI_NUMERICHOST);
     95     return ret;
     96 }
     97