180 строки
4.7 KiB
C
180 строки
4.7 KiB
C
/* Copyright 1998 by the Massachusetts Institute of Technology.
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*
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* Permission to use, copy, modify, and distribute this
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* software and its documentation for any purpose and without
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* fee is hereby granted, provided that the above copyright
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* notice appear in all copies and that both that copyright
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* notice and this permission notice appear in supporting
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* documentation, and that the name of M.I.T. not be used in
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* advertising or publicity pertaining to distribution of the
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* software without specific, written prior permission.
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* M.I.T. makes no representations about the suitability of
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* this software for any purpose. It is provided "as is"
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* without express or implied warranty.
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*/
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/*
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* ares_parse_ns_reply created by Vlad Dinulescu <vlad.dinulescu@avira.com>
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* on behalf of AVIRA Gmbh - http://www.avira.com
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*/
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#include "setup.h"
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#ifdef HAVE_SYS_SOCKET_H
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# include <sys/socket.h>
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#endif
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#ifdef HAVE_NETINET_IN_H
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# include <netinet/in.h>
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#endif
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#ifdef HAVE_NETDB_H
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# include <netdb.h>
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#endif
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#ifdef HAVE_ARPA_INET_H
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# include <arpa/inet.h>
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#endif
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#ifdef HAVE_ARPA_NAMESER_H
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# include <arpa/nameser.h>
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#else
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# include "nameser.h"
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#endif
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#ifdef HAVE_ARPA_NAMESER_COMPAT_H
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# include <arpa/nameser_compat.h>
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#endif
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#include <stdlib.h>
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#include <string.h>
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#include "ares.h"
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#include "ares_dns.h"
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#include "ares_private.h"
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int ares_parse_ns_reply( const unsigned char* abuf, int alen,
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struct hostent** host )
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{
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unsigned int qdcount, ancount;
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int status, i, rr_type, rr_class, rr_len;
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int nameservers_num;
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long len;
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const unsigned char *aptr;
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char* hostname, *rr_name, *rr_data, **nameservers;
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struct hostent *hostent;
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/* Set *host to NULL for all failure cases. */
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*host = NULL;
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/* Give up if abuf doesn't have room for a header. */
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if ( alen < HFIXEDSZ )
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return ARES_EBADRESP;
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/* Fetch the question and answer count from the header. */
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qdcount = DNS_HEADER_QDCOUNT( abuf );
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ancount = DNS_HEADER_ANCOUNT( abuf );
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if ( qdcount != 1 )
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return ARES_EBADRESP;
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/* Expand the name from the question, and skip past the question. */
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aptr = abuf + HFIXEDSZ;
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status = ares_expand_name( aptr, abuf, alen, &hostname, &len );
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if ( status != ARES_SUCCESS )
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return status;
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if ( aptr + len + QFIXEDSZ > abuf + alen )
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{
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free( hostname );
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return ARES_EBADRESP;
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}
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aptr += len + QFIXEDSZ;
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/* Allocate nameservers array; ancount gives an upper bound */
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nameservers = malloc( ( ancount + 1 ) * sizeof( char * ) );
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if ( !nameservers )
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{
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free( hostname );
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return ARES_ENOMEM;
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}
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nameservers_num = 0;
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/* Examine each answer resource record (RR) in turn. */
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for ( i = 0; i < ( int ) ancount; i++ )
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{
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/* Decode the RR up to the data field. */
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status = ares_expand_name( aptr, abuf, alen, &rr_name, &len );
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if ( status != ARES_SUCCESS )
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break;
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aptr += len;
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if ( aptr + RRFIXEDSZ > abuf + alen )
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{
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status = ARES_EBADRESP;
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break;
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}
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rr_type = DNS_RR_TYPE( aptr );
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rr_class = DNS_RR_CLASS( aptr );
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rr_len = DNS_RR_LEN( aptr );
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aptr += RRFIXEDSZ;
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if ( rr_class == C_IN && rr_type == T_NS )
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{
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/* Decode the RR data and add it to the nameservers list */
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status = ares_expand_name( aptr, abuf, alen, &rr_data, &len );
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if ( status != ARES_SUCCESS )
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{
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break;
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}
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nameservers[nameservers_num] = malloc(strlen(rr_data)+1);
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if (nameservers[nameservers_num]==NULL)
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{
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free(rr_name);
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free(rr_data);
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status=ARES_ENOMEM;
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break;
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}
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strcpy(nameservers[nameservers_num],rr_data);
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free(rr_data);
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nameservers_num++;
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}
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free( rr_name );
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aptr += rr_len;
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if ( aptr > abuf + alen )
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{
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status = ARES_EBADRESP;
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break;
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}
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}
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if ( status == ARES_SUCCESS && nameservers_num == 0 )
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{
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status = ARES_ENODATA;
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}
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if ( status == ARES_SUCCESS )
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{
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/* We got our answer. Allocate memory to build the host entry. */
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nameservers[nameservers_num] = NULL;
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hostent = malloc( sizeof( struct hostent ) );
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if ( hostent )
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{
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hostent->h_addr_list = malloc( 1 * sizeof( char * ) );
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if ( hostent->h_addr_list )
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{
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/* Fill in the hostent and return successfully. */
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hostent->h_name = hostname;
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hostent->h_aliases = nameservers;
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hostent->h_addrtype = AF_INET;
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hostent->h_length = sizeof( struct in_addr );
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hostent->h_addr_list[0] = NULL;
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*host = hostent;
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return ARES_SUCCESS;
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}
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free( hostent );
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}
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status = ARES_ENOMEM;
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}
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for ( i = 0; i < nameservers_num; i++ )
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free( nameservers[i] );
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free( nameservers );
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free( hostname );
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return status;
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}
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