257 строки
7.0 KiB
C
257 строки
7.0 KiB
C
/* $Id$ */
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/* Copyright 2005 Dominick Meglio
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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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#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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#ifdef HAVE_STRINGS_H
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# include <strings.h>
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#endif
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#include <stdlib.h>
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#include <string.h>
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#ifdef HAVE_LIMITS_H
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# include <limits.h>
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#endif
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#include "ares.h"
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#include "ares_dns.h"
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#include "inet_net_pton.h"
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#include "ares_private.h"
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int ares_parse_aaaa_reply(const unsigned char *abuf, int alen,
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struct hostent **host, struct addr6ttl *addrttls,
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int *naddrttls)
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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, rr_ttl, naddrs;
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int cname_ttl = INT_MAX; /* the TTL imposed by the CNAME chain */
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int naliases;
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long len;
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const unsigned char *aptr;
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char *hostname, *rr_name, *rr_data, **aliases;
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struct in6_addr *addrs;
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struct hostent *hostent;
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const int max_addr_ttls = (addrttls && naddrttls) ? *naddrttls : 0;
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/* Set *host to NULL for all failure cases. */
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if (host)
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*host = NULL;
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/* Same with *naddrttls. */
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if (naddrttls)
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*naddrttls = 0;
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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_for_response(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 addresses and aliases; ancount gives an upper bound for both. */
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if (host)
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{
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addrs = malloc(ancount * sizeof(struct in6_addr));
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if (!addrs)
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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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aliases = malloc((ancount + 1) * sizeof(char *));
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if (!aliases)
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{
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free(hostname);
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free(addrs);
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return ARES_ENOMEM;
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}
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}
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else
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{
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addrs = NULL;
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aliases = NULL;
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}
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naddrs = 0;
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naliases = 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_for_response(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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rr_ttl = DNS_RR_TTL(aptr);
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aptr += RRFIXEDSZ;
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if (rr_class == C_IN && rr_type == T_AAAA
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&& rr_len == sizeof(struct in6_addr)
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&& strcasecmp(rr_name, hostname) == 0)
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{
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if (addrs)
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{
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if (aptr + sizeof(struct in6_addr) > 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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memcpy(&addrs[naddrs], aptr, sizeof(struct in6_addr));
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}
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if (naddrs < max_addr_ttls)
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{
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struct addr6ttl * const at = &addrttls[naddrs];
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if (aptr + sizeof(struct in6_addr) > 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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memcpy(&at->ip6addr, aptr, sizeof(struct in6_addr));
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at->ttl = rr_ttl;
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}
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naddrs++;
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status = ARES_SUCCESS;
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}
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if (rr_class == C_IN && rr_type == T_CNAME)
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{
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/* Record the RR name as an alias. */
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if (aliases)
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aliases[naliases] = rr_name;
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else
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free(rr_name);
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naliases++;
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/* Decode the RR data and replace the hostname with it. */
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status = ares__expand_name_for_response(aptr, abuf, alen, &rr_data,
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&len);
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if (status != ARES_SUCCESS)
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break;
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free(hostname);
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hostname = rr_data;
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/* Take the min of the TTLs we see in the CNAME chain. */
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if (cname_ttl > rr_ttl)
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cname_ttl = rr_ttl;
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}
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else
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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 && naddrs == 0)
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status = ARES_ENODATA;
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if (status == ARES_SUCCESS)
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{
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/* We got our answer. */
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if (naddrttls)
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{
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const int n = naddrs < max_addr_ttls ? naddrs : max_addr_ttls;
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for (i = 0; i < n; i++)
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{
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/* Ensure that each A TTL is no larger than the CNAME TTL. */
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if (addrttls[i].ttl > cname_ttl)
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addrttls[i].ttl = cname_ttl;
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}
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*naddrttls = n;
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}
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if (aliases)
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aliases[naliases] = NULL;
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if (host)
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{
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/* Allocate memory to build the host entry. */
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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((naddrs + 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 = aliases;
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hostent->h_addrtype = AF_INET6;
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hostent->h_length = sizeof(struct in6_addr);
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for (i = 0; i < naddrs; i++)
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hostent->h_addr_list[i] = (char *) &addrs[i];
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hostent->h_addr_list[naddrs] = 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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}
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if (aliases)
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{
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for (i = 0; i < naliases; i++)
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free(aliases[i]);
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free(aliases);
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}
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free(addrs);
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free(hostname);
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return status;
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}
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