| |
| /* Copyright 1998 by the Massachusetts Institute of Technology. |
| * Copyright (C) 2009 by Jakub Hrozek <jhrozek@redhat.com> |
| * |
| * 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. |
| */ |
| |
| #include "ares_setup.h" |
| |
| #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 |
| |
| #ifdef HAVE_STRINGS_H |
| # include <strings.h> |
| #endif |
| |
| #include "ares.h" |
| #include "ares_dns.h" |
| #include "ares_data.h" |
| #include "ares_private.h" |
| |
| static int |
| ares__parse_txt_reply (const unsigned char *abuf, int alen, |
| int ex, void **txt_out) |
| { |
| size_t substr_len; |
| unsigned int qdcount, ancount, i; |
| const unsigned char *aptr; |
| const unsigned char *strptr; |
| int status, rr_type, rr_class, rr_len; |
| long len; |
| char *hostname = NULL, *rr_name = NULL; |
| struct ares_txt_ext *txt_head = NULL; |
| struct ares_txt_ext *txt_last = NULL; |
| struct ares_txt_ext *txt_curr; |
| |
| /* Set *txt_out to NULL for all failure cases. */ |
| *txt_out = 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; |
| if (ancount == 0) |
| return ARES_ENODATA; |
| |
| /* Expand the name from the question, and skip past the question. */ |
| aptr = abuf + HFIXEDSZ; |
| status = ares_expand_name (aptr, abuf, alen, &hostname, &len); |
| if (status != ARES_SUCCESS) |
| return status; |
| |
| if (aptr + len + QFIXEDSZ > abuf + alen) |
| { |
| ares_free (hostname); |
| return ARES_EBADRESP; |
| } |
| aptr += len + QFIXEDSZ; |
| |
| /* Examine each answer resource record (RR) in turn. */ |
| for (i = 0; i < ancount; i++) |
| { |
| /* Decode the RR up to the data field. */ |
| status = ares_expand_name (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 (aptr + rr_len > abuf + alen) |
| { |
| status = ARES_EBADRESP; |
| break; |
| } |
| |
| /* Check if we are really looking at a TXT record */ |
| if (rr_class == C_IN && rr_type == T_TXT) |
| { |
| /* |
| * There may be multiple substrings in a single TXT record. Each |
| * substring may be up to 255 characters in length, with a |
| * "length byte" indicating the size of the substring payload. |
| * RDATA contains both the length-bytes and payloads of all |
| * substrings contained therein. |
| */ |
| |
| strptr = aptr; |
| while (strptr < (aptr + rr_len)) |
| { |
| substr_len = (unsigned char)*strptr; |
| if (strptr + substr_len + 1 > aptr + rr_len) |
| { |
| status = ARES_EBADRESP; |
| break; |
| } |
| |
| /* Allocate storage for this TXT answer appending it to the list */ |
| txt_curr = ares_malloc_data(ex ? ARES_DATATYPE_TXT_EXT : |
| ARES_DATATYPE_TXT_REPLY); |
| if (!txt_curr) |
| { |
| status = ARES_ENOMEM; |
| break; |
| } |
| if (txt_last) |
| { |
| txt_last->next = txt_curr; |
| } |
| else |
| { |
| txt_head = txt_curr; |
| } |
| txt_last = txt_curr; |
| |
| if (ex) |
| txt_curr->record_start = (strptr == aptr); |
| txt_curr->length = substr_len; |
| txt_curr->txt = ares_malloc (substr_len + 1/* Including null byte */); |
| if (txt_curr->txt == NULL) |
| { |
| status = ARES_ENOMEM; |
| break; |
| } |
| |
| ++strptr; |
| memcpy ((char *) txt_curr->txt, strptr, substr_len); |
| |
| /* Make sure we NULL-terminate */ |
| txt_curr->txt[substr_len] = 0; |
| |
| strptr += substr_len; |
| } |
| } |
| |
| /* Propagate any failures */ |
| if (status != ARES_SUCCESS) |
| { |
| break; |
| } |
| |
| /* Don't lose memory in the next iteration */ |
| ares_free (rr_name); |
| rr_name = NULL; |
| |
| /* Move on to the next record */ |
| aptr += rr_len; |
| } |
| |
| if (hostname) |
| ares_free (hostname); |
| if (rr_name) |
| ares_free (rr_name); |
| |
| /* clean up on error */ |
| if (status != ARES_SUCCESS) |
| { |
| if (txt_head) |
| ares_free_data (txt_head); |
| return status; |
| } |
| |
| /* everything looks fine, return the data */ |
| *txt_out = txt_head; |
| |
| return ARES_SUCCESS; |
| } |
| |
| int |
| ares_parse_txt_reply (const unsigned char *abuf, int alen, |
| struct ares_txt_reply **txt_out) |
| { |
| return ares__parse_txt_reply(abuf, alen, 0, (void **) txt_out); |
| } |
| |
| |
| int |
| ares_parse_txt_reply_ext (const unsigned char *abuf, int alen, |
| struct ares_txt_ext **txt_out) |
| { |
| return ares__parse_txt_reply(abuf, alen, 1, (void **) txt_out); |
| } |