1 2 /* Copyright 1998 by the Massachusetts Institute of Technology. 3 * Copyright 2005 Dominick Meglio 4 * 5 * Permission to use, copy, modify, and distribute this 6 * software and its documentation for any purpose and without 7 * fee is hereby granted, provided that the above copyright 8 * notice appear in all copies and that both that copyright 9 * notice and this permission notice appear in supporting 10 * documentation, and that the name of M.I.T. not be used in 11 * advertising or publicity pertaining to distribution of the 12 * software without specific, written prior permission. 13 * M.I.T. makes no representations about the suitability of 14 * this software for any purpose. It is provided "as is" 15 * without express or implied warranty. 16 */ 17 18 #include "ares_setup.h" 19 20 #ifdef HAVE_SYS_SOCKET_H 21 # include <sys/socket.h> 22 #endif 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 #ifdef HAVE_STRINGS_H 42 # include <strings.h> 43 #endif 44 45 #include <stdlib.h> 46 #include <string.h> 47 #ifdef HAVE_LIMITS_H 48 # include <limits.h> 49 #endif 50 51 #include "ares.h" 52 #include "ares_dns.h" 53 #include "inet_net_pton.h" 54 #include "ares_private.h" 55 56 int ares_parse_aaaa_reply(const unsigned char *abuf, int alen, 57 struct hostent **host, struct ares_addr6ttl *addrttls, 58 int *naddrttls) 59 { 60 unsigned int qdcount, ancount; 61 int status, i, rr_type, rr_class, rr_len, rr_ttl, naddrs; 62 int cname_ttl = INT_MAX; /* the TTL imposed by the CNAME chain */ 63 int naliases; 64 long len; 65 const unsigned char *aptr; 66 char *hostname, *rr_name, *rr_data, **aliases; 67 struct ares_in6_addr *addrs; 68 struct hostent *hostent; 69 const int max_addr_ttls = (addrttls && naddrttls) ? *naddrttls : 0; 70 71 /* Set *host to NULL for all failure cases. */ 72 if (host) 73 *host = NULL; 74 /* Same with *naddrttls. */ 75 if (naddrttls) 76 *naddrttls = 0; 77 78 /* Give up if abuf doesn't have room for a header. */ 79 if (alen < HFIXEDSZ) 80 return ARES_EBADRESP; 81 82 /* Fetch the question and answer count from the header. */ 83 qdcount = DNS_HEADER_QDCOUNT(abuf); 84 ancount = DNS_HEADER_ANCOUNT(abuf); 85 if (qdcount != 1) 86 return ARES_EBADRESP; 87 88 /* Expand the name from the question, and skip past the question. */ 89 aptr = abuf + HFIXEDSZ; 90 status = ares__expand_name_for_response(aptr, abuf, alen, &hostname, &len); 91 if (status != ARES_SUCCESS) 92 return status; 93 if (aptr + len + QFIXEDSZ > abuf + alen) 94 { 95 free(hostname); 96 return ARES_EBADRESP; 97 } 98 aptr += len + QFIXEDSZ; 99 100 /* Allocate addresses and aliases; ancount gives an upper bound for both. */ 101 if (host) 102 { 103 addrs = malloc(ancount * sizeof(struct ares_in6_addr)); 104 if (!addrs) 105 { 106 free(hostname); 107 return ARES_ENOMEM; 108 } 109 aliases = malloc((ancount + 1) * sizeof(char *)); 110 if (!aliases) 111 { 112 free(hostname); 113 free(addrs); 114 return ARES_ENOMEM; 115 } 116 } 117 else 118 { 119 addrs = NULL; 120 aliases = NULL; 121 } 122 naddrs = 0; 123 naliases = 0; 124 125 /* Examine each answer resource record (RR) in turn. */ 126 for (i = 0; i < (int)ancount; i++) 127 { 128 /* Decode the RR up to the data field. */ 129 status = ares__expand_name_for_response(aptr, abuf, alen, &rr_name, &len); 130 if (status != ARES_SUCCESS) 131 break; 132 aptr += len; 133 if (aptr + RRFIXEDSZ > abuf + alen) 134 { 135 free(rr_name); 136 status = ARES_EBADRESP; 137 break; 138 } 139 rr_type = DNS_RR_TYPE(aptr); 140 rr_class = DNS_RR_CLASS(aptr); 141 rr_len = DNS_RR_LEN(aptr); 142 rr_ttl = DNS_RR_TTL(aptr); 143 aptr += RRFIXEDSZ; 144 145 if (rr_class == C_IN && rr_type == T_AAAA 146 && rr_len == sizeof(struct ares_in6_addr) 147 && strcasecmp(rr_name, hostname) == 0) 148 { 149 if (addrs) 150 { 151 if (aptr + sizeof(struct ares_in6_addr) > abuf + alen) 152 { 153 free(rr_name); 154 status = ARES_EBADRESP; 155 break; 156 } 157 memcpy(&addrs[naddrs], aptr, sizeof(struct ares_in6_addr)); 158 } 159 if (naddrs < max_addr_ttls) 160 { 161 struct ares_addr6ttl * const at = &addrttls[naddrs]; 162 if (aptr + sizeof(struct ares_in6_addr) > abuf + alen) 163 { 164 free(rr_name); 165 status = ARES_EBADRESP; 166 break; 167 } 168 memcpy(&at->ip6addr, aptr, sizeof(struct ares_in6_addr)); 169 at->ttl = rr_ttl; 170 } 171 naddrs++; 172 status = ARES_SUCCESS; 173 } 174 175 if (rr_class == C_IN && rr_type == T_CNAME) 176 { 177 /* Record the RR name as an alias. */ 178 if (aliases) 179 aliases[naliases] = rr_name; 180 else 181 free(rr_name); 182 naliases++; 183 184 /* Decode the RR data and replace the hostname with it. */ 185 status = ares__expand_name_for_response(aptr, abuf, alen, &rr_data, 186 &len); 187 if (status != ARES_SUCCESS) 188 break; 189 free(hostname); 190 hostname = rr_data; 191 192 /* Take the min of the TTLs we see in the CNAME chain. */ 193 if (cname_ttl > rr_ttl) 194 cname_ttl = rr_ttl; 195 } 196 else 197 free(rr_name); 198 199 aptr += rr_len; 200 if (aptr > abuf + alen) 201 { 202 status = ARES_EBADRESP; 203 break; 204 } 205 } 206 207 if (status == ARES_SUCCESS && naddrs == 0) 208 status = ARES_ENODATA; 209 if (status == ARES_SUCCESS) 210 { 211 /* We got our answer. */ 212 if (naddrttls) 213 { 214 const int n = naddrs < max_addr_ttls ? naddrs : max_addr_ttls; 215 for (i = 0; i < n; i++) 216 { 217 /* Ensure that each A TTL is no larger than the CNAME TTL. */ 218 if (addrttls[i].ttl > cname_ttl) 219 addrttls[i].ttl = cname_ttl; 220 } 221 *naddrttls = n; 222 } 223 if (aliases) 224 aliases[naliases] = NULL; 225 if (host) 226 { 227 /* Allocate memory to build the host entry. */ 228 hostent = malloc(sizeof(struct hostent)); 229 if (hostent) 230 { 231 hostent->h_addr_list = malloc((naddrs + 1) * sizeof(char *)); 232 if (hostent->h_addr_list) 233 { 234 /* Fill in the hostent and return successfully. */ 235 hostent->h_name = hostname; 236 hostent->h_aliases = aliases; 237 hostent->h_addrtype = AF_INET6; 238 hostent->h_length = sizeof(struct ares_in6_addr); 239 for (i = 0; i < naddrs; i++) 240 hostent->h_addr_list[i] = (char *) &addrs[i]; 241 hostent->h_addr_list[naddrs] = NULL; 242 *host = hostent; 243 return ARES_SUCCESS; 244 } 245 free(hostent); 246 } 247 status = ARES_ENOMEM; 248 } 249 } 250 if (aliases) 251 { 252 for (i = 0; i < naliases; i++) 253 free(aliases[i]); 254 free(aliases); 255 } 256 free(addrs); 257 free(hostname); 258 return status; 259 } 260
