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