ceph/src/c-ares/ares_parse_ns_reply.c

   1 /* Copyright 1998 by the Massachusetts Institute of Technology.
   2  *
   3  * Permission to use, copy, modify, and distribute this
   4  * software and its documentation for any purpose and without
   5  * fee is hereby granted, provided that the above copyright
   6  * notice appear in all copies and that both that copyright
   7  * notice and this permission notice appear in supporting
   8  * documentation, and that the name of M.I.T. not be used in
   9  * advertising or publicity pertaining to distribution of the
  10  * software without specific, written prior permission.
  11  * M.I.T. makes no representations about the suitability of
  12  * this software for any purpose.  It is provided "as is"
  13  * without express or implied warranty.
  14  */
  15
  16 /*
  17  * ares_parse_ns_reply created by Vlad Dinulescu <vlad.dinulescu@avira.com>
  18  *      on behalf of AVIRA Gmbh - http://www.avira.com
  19  */
  20
  21 #include "ares_setup.h"
  22
  23 #ifdef HAVE_NETINET_IN_H
  24 #  include <netinet/in.h>
  25 #endif
  26 #ifdef HAVE_NETDB_H
  27 #  include <netdb.h>
  28 #endif
  29 #ifdef HAVE_ARPA_INET_H
  30 #  include <arpa/inet.h>
  31 #endif
  32 #ifdef HAVE_ARPA_NAMESER_H
  33 #  include <arpa/nameser.h>
  34 #else
  35 #  include "nameser.h"
  36 #endif
  37 #ifdef HAVE_ARPA_NAMESER_COMPAT_H
  38 #  include <arpa/nameser_compat.h>
  39 #endif
  40
  41 #include "ares.h"
  42 #include "ares_dns.h"
  43 #include "ares_private.h"
  44
  45 int ares_parse_ns_reply( const unsigned char* abuf, int alen,
  46                          struct hostent** host )
  47 {
  48   unsigned int qdcount, ancount;
  49   int status, i, rr_type, rr_class, rr_len;
  50   int nameservers_num;
  51   long len;
  52   const unsigned char *aptr;
  53   char* hostname, *rr_name, *rr_data, **nameservers;
  54   struct hostent *hostent;
  55
  56   /* Set *host to NULL for all failure cases. */
  57   *host = NULL;
  58
  59   /* Give up if abuf doesn't have room for a header. */
  60   if ( alen < HFIXEDSZ )
  61     return ARES_EBADRESP;
  62
  63   /* Fetch the question and answer count from the header. */
  64   qdcount = DNS_HEADER_QDCOUNT( abuf );
  65   ancount = DNS_HEADER_ANCOUNT( abuf );
  66   if ( qdcount != 1 )
  67     return ARES_EBADRESP;
  68
  69   /* Expand the name from the question, and skip past the question. */
  70   aptr = abuf + HFIXEDSZ;
  71   status = ares__expand_name_for_response( aptr, abuf, alen, &hostname, &len);
  72   if ( status != ARES_SUCCESS )
  73     return status;
  74   if ( aptr + len + QFIXEDSZ > abuf + alen )
  75   {
  76     ares_free( hostname );
  77     return ARES_EBADRESP;
  78   }
  79   aptr += len + QFIXEDSZ;
  80
  81   /* Allocate nameservers array; ancount gives an upper bound */
  82   nameservers = ares_malloc( ( ancount + 1 ) * sizeof( char * ) );
  83   if ( !nameservers )
  84   {
  85     ares_free( hostname );
  86     return ARES_ENOMEM;
  87   }
  88   nameservers_num = 0;
  89
  90   /* Examine each answer resource record (RR) in turn. */
  91   for ( i = 0; i < ( int ) ancount; i++ )
  92   {
  93     /* Decode the RR up to the data field. */
  94     status = ares__expand_name_for_response( aptr, abuf, alen, &rr_name, &len );
  95     if ( status != ARES_SUCCESS )
  96       break;
  97     aptr += len;
  98     if ( aptr + RRFIXEDSZ > abuf + alen )
  99     {
 100       status = ARES_EBADRESP;
 101       ares_free(rr_name);
 102       break;
 103     }
 104     rr_type = DNS_RR_TYPE( aptr );
 105     rr_class = DNS_RR_CLASS( aptr );
 106     rr_len = DNS_RR_LEN( aptr );
 107     aptr += RRFIXEDSZ;
 108     if (aptr + rr_len > abuf + alen)
 109       {
 110         ares_free(rr_name);
 111         status = ARES_EBADRESP;
 112         break;
 113       }
 114
 115     if ( rr_class == C_IN && rr_type == T_NS )
 116     {
 117       /* Decode the RR data and add it to the nameservers list */
 118       status = ares__expand_name_for_response( aptr, abuf, alen, &rr_data,
 119                                                &len);
 120       if ( status != ARES_SUCCESS )
 121       {
 122         ares_free(rr_name);
 123         break;
 124       }
 125
 126       nameservers[nameservers_num] = ares_malloc(strlen(rr_data)+1);
 127
 128       if (nameservers[nameservers_num]==NULL)
 129       {
 130         ares_free(rr_name);
 131         ares_free(rr_data);
 132         status=ARES_ENOMEM;
 133         break;
 134       }
 135       strcpy(nameservers[nameservers_num],rr_data);
 136       ares_free(rr_data);
 137
 138       nameservers_num++;
 139     }
 140
 141     ares_free( rr_name );
 142
 143     aptr += rr_len;
 144     if ( aptr > abuf + alen )
 145     {  /* LCOV_EXCL_START: already checked above */
 146       status = ARES_EBADRESP;
 147       break;
 148     }  /* LCOV_EXCL_STOP */
 149   }
 150
 151   if ( status == ARES_SUCCESS && nameservers_num == 0 )
 152   {
 153     status = ARES_ENODATA;
 154   }
 155   if ( status == ARES_SUCCESS )
 156   {
 157     /* We got our answer.  Allocate memory to build the host entry. */
 158     nameservers[nameservers_num] = NULL;
 159     hostent = ares_malloc( sizeof( struct hostent ) );
 160     if ( hostent )
 161     {
 162       hostent->h_addr_list = ares_malloc( 1 * sizeof( char * ) );
 163       if ( hostent->h_addr_list )
 164       {
 165         /* Fill in the hostent and return successfully. */
 166         hostent->h_name = hostname;
 167         hostent->h_aliases = nameservers;
 168         hostent->h_addrtype = AF_INET;
 169         hostent->h_length = sizeof( struct in_addr );
 170         hostent->h_addr_list[0] = NULL;
 171         *host = hostent;
 172         return ARES_SUCCESS;
 173       }
 174       ares_free( hostent );
 175     }
 176     status = ARES_ENOMEM;
 177   }
 178   for ( i = 0; i < nameservers_num; i++ )
 179     ares_free( nameservers[i] );
 180   ares_free( nameservers );
 181   ares_free( hostname );
 182   return status;
 183 }