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 (at) avira.com> 18 * on behalf of AVIRA Gmbh - http://www.avira.com 19 */ 20 21 #include "ares_setup.h" 22 23 #ifdef HAVE_SYS_SOCKET_H 24 # include <sys/socket.h> 25 #endif 26 #ifdef HAVE_NETINET_IN_H 27 # include <netinet/in.h> 28 #endif 29 #ifdef HAVE_NETDB_H 30 # include <netdb.h> 31 #endif 32 #ifdef HAVE_ARPA_INET_H 33 # include <arpa/inet.h> 34 #endif 35 #ifdef HAVE_ARPA_NAMESER_H 36 # include <arpa/nameser.h> 37 #else 38 # include "nameser.h" 39 #endif 40 #ifdef HAVE_ARPA_NAMESER_COMPAT_H 41 # include <arpa/nameser_compat.h> 42 #endif 43 44 #include <stdlib.h> 45 #include <string.h> 46 #include "ares.h" 47 #include "ares_dns.h" 48 #include "ares_private.h" 49 50 int ares_parse_ns_reply( const unsigned char* abuf, int alen, 51 struct hostent** host ) 52 { 53 unsigned int qdcount, ancount; 54 int status, i, rr_type, rr_class, rr_len; 55 int nameservers_num; 56 long len; 57 const unsigned char *aptr; 58 char* hostname, *rr_name, *rr_data, **nameservers; 59 struct hostent *hostent; 60 61 /* Set *host to NULL for all failure cases. */ 62 *host = NULL; 63 64 /* Give up if abuf doesn't have room for a header. */ 65 if ( alen < HFIXEDSZ ) 66 return ARES_EBADRESP; 67 68 /* Fetch the question and answer count from the header. */ 69 qdcount = DNS_HEADER_QDCOUNT( abuf ); 70 ancount = DNS_HEADER_ANCOUNT( abuf ); 71 if ( qdcount != 1 ) 72 return ARES_EBADRESP; 73 74 /* Expand the name from the question, and skip past the question. */ 75 aptr = abuf + HFIXEDSZ; 76 status = ares__expand_name_for_response( aptr, abuf, alen, &hostname, &len); 77 if ( status != ARES_SUCCESS ) 78 return status; 79 if ( aptr + len + QFIXEDSZ > abuf + alen ) 80 { 81 free( hostname ); 82 return ARES_EBADRESP; 83 } 84 aptr += len + QFIXEDSZ; 85 86 /* Allocate nameservers array; ancount gives an upper bound */ 87 nameservers = malloc( ( ancount + 1 ) * sizeof( char * ) ); 88 if ( !nameservers ) 89 { 90 free( hostname ); 91 return ARES_ENOMEM; 92 } 93 nameservers_num = 0; 94 95 /* Examine each answer resource record (RR) in turn. */ 96 for ( i = 0; i < ( int ) ancount; i++ ) 97 { 98 /* Decode the RR up to the data field. */ 99 status = ares__expand_name_for_response( aptr, abuf, alen, &rr_name, &len ); 100 if ( status != ARES_SUCCESS ) 101 break; 102 aptr += len; 103 if ( aptr + RRFIXEDSZ > abuf + alen ) 104 { 105 status = ARES_EBADRESP; 106 free(rr_name); 107 break; 108 } 109 rr_type = DNS_RR_TYPE( aptr ); 110 rr_class = DNS_RR_CLASS( aptr ); 111 rr_len = DNS_RR_LEN( aptr ); 112 aptr += RRFIXEDSZ; 113 114 if ( rr_class == C_IN && rr_type == T_NS ) 115 { 116 /* Decode the RR data and add it to the nameservers list */ 117 status = ares__expand_name_for_response( aptr, abuf, alen, &rr_data, 118 &len); 119 if ( status != ARES_SUCCESS ) 120 { 121 free(rr_name); 122 break; 123 } 124 125 nameservers[nameservers_num] = malloc(strlen(rr_data)+1); 126 127 if (nameservers[nameservers_num]==NULL) 128 { 129 free(rr_name); 130 free(rr_data); 131 status=ARES_ENOMEM; 132 break; 133 } 134 strcpy(nameservers[nameservers_num],rr_data); 135 free(rr_data); 136 137 nameservers_num++; 138 } 139 140 free( rr_name ); 141 142 aptr += rr_len; 143 if ( aptr > abuf + alen ) 144 { 145 status = ARES_EBADRESP; 146 break; 147 } 148 } 149 150 if ( status == ARES_SUCCESS && nameservers_num == 0 ) 151 { 152 status = ARES_ENODATA; 153 } 154 if ( status == ARES_SUCCESS ) 155 { 156 /* We got our answer. Allocate memory to build the host entry. */ 157 nameservers[nameservers_num] = NULL; 158 hostent = malloc( sizeof( struct hostent ) ); 159 if ( hostent ) 160 { 161 hostent->h_addr_list = malloc( 1 * sizeof( char * ) ); 162 if ( hostent->h_addr_list ) 163 { 164 /* Fill in the hostent and return successfully. */ 165 hostent->h_name = hostname; 166 hostent->h_aliases = nameservers; 167 hostent->h_addrtype = AF_INET; 168 hostent->h_length = sizeof( struct in_addr ); 169 hostent->h_addr_list[0] = NULL; 170 *host = hostent; 171 return ARES_SUCCESS; 172 } 173 free( hostent ); 174 } 175 status = ARES_ENOMEM; 176 } 177 for ( i = 0; i < nameservers_num; i++ ) 178 free( nameservers[i] ); 179 free( nameservers ); 180 free( hostname ); 181 return status; 182 } 183
