192 строки
5.7 KiB
C
192 строки
5.7 KiB
C
/* $Id$ */
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/* 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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#include "setup.h"
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#if defined(WIN32) && !defined(WATT32)
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#include "nameser.h"
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#else
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <netdb.h>
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#include <arpa/nameser.h>
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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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#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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#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_ptr_reply(const unsigned char *abuf, int alen, const void *addr,
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int addrlen, int family, 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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long len;
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const unsigned char *aptr;
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char *ptrname, *hostname, *rr_name, *rr_data;
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struct hostent *hostent;
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int aliascnt = 0;
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char ** aliases;
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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, &ptrname, &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(ptrname);
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return ARES_EBADRESP;
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}
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aptr += len + QFIXEDSZ;
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/* Examine each answer resource record (RR) in turn. */
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hostname = NULL;
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aliases = malloc(8 * sizeof(char *));
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if (!aliases)
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{
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free(ptrname);
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return ARES_ENOMEM;
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}
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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_PTR
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&& strcasecmp(rr_name, ptrname) == 0)
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{
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/* Decode the RR data and set hostname to it. */
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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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break;
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if (hostname)
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free(hostname);
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hostname = rr_data;
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aliases[aliascnt] = malloc((strlen(rr_data)+1) * sizeof(char *));
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if (!aliases[aliascnt])
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{
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status = ARES_ENOMEM;
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break;
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}
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strncpy(aliases[aliascnt], rr_data, strlen(rr_data)+1);
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aliascnt++;
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if ((aliascnt%8)==0)
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aliases = realloc(aliases, (aliascnt/16+1) * sizeof(char *));
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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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/* Decode the RR data and replace ptrname with it. */
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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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break;
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free(ptrname);
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ptrname = rr_data;
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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 && !hostname)
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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. 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(2 * sizeof(char *));
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if (hostent->h_addr_list)
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{
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hostent->h_addr_list[0] = malloc(addrlen);
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if (hostent->h_addr_list[0])
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{
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hostent->h_aliases = malloc((aliascnt+1) * sizeof (char *));
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if (hostent->h_aliases)
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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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for (i=0 ; i<aliascnt ; i++)
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hostent->h_aliases[i] = aliases[i];
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hostent->h_aliases[aliascnt] = NULL;
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hostent->h_addrtype = family;
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hostent->h_length = addrlen;
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memcpy(hostent->h_addr_list[0], addr, addrlen);
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hostent->h_addr_list[1] = NULL;
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*host = hostent;
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free(aliases);
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free(ptrname);
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return ARES_SUCCESS;
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}
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free(hostent->h_addr_list[0]);
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}
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free(hostent->h_addr_list);
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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<aliascnt ; i++)
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if (aliases[i])
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free(aliases[i]);
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free(aliases);
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if (hostname)
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free(hostname);
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free(ptrname);
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return status;
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}
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