| /* $Id$ */ |
| |
| /* Copyright 1998 by the Massachusetts Institute of Technology. |
| * Copyright (C) 2009 Jakub Hrozek <jhrozek@redhat.com> |
| * Copyright (C) 2009 Yang Tse <yangsita@gmail.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_SYS_SOCKET_H |
| # include <sys/socket.h> |
| #endif |
| #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 <stdlib.h> |
| #include <string.h> |
| |
| #include "ares.h" |
| #include "ares_dns.h" |
| #include "ares_private.h" |
| |
| int |
| ares_parse_txt_reply (const unsigned char *abuf, int alen, |
| struct ares_txt_reply **txt_out, int *ntxtreply) |
| { |
| size_t substr_len, str_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_reply *txt = NULL; |
| |
| /* Set *txt_out to NULL for all failure cases. */ |
| *txt_out = NULL; |
| |
| /* Same with *ntxtreply. */ |
| *ntxtreply = 0; |
| |
| /* 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) |
| { |
| free (hostname); |
| return ARES_EBADRESP; |
| } |
| aptr += len + QFIXEDSZ; |
| |
| /* Allocate ares_txt_reply array; ancount gives an upper bound */ |
| txt = malloc ((ancount) * sizeof (struct ares_txt_reply)); |
| if (!txt) |
| { |
| free (hostname); |
| return ARES_ENOMEM; |
| } |
| |
| /* Initialize ares_txt_reply array */ |
| for (i = 0; i < ancount; i++) |
| { |
| txt[i].txt = NULL; |
| txt[i].length = 0; |
| } |
| |
| /* 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; |
| |
| /* 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. |
| */ |
| |
| /* Compute total length to allow a single memory allocation */ |
| strptr = aptr; |
| while (strptr < (aptr + rr_len)) |
| { |
| substr_len = (unsigned char)*strptr; |
| txt[i].length += substr_len; |
| strptr += substr_len + 1; |
| } |
| |
| /* Including null byte */ |
| txt[i].txt = malloc (txt[i].length + 1); |
| if (txt[i].txt == NULL) |
| { |
| status = ARES_ENOMEM; |
| break; |
| } |
| |
| /* Step through the list of substrings, concatenating them */ |
| str_len = 0; |
| strptr = aptr; |
| while (strptr < (aptr + rr_len)) |
| { |
| substr_len = (unsigned char)*strptr; |
| strptr++; |
| memcpy ((char *) txt[i].txt + str_len, strptr, substr_len); |
| str_len += substr_len; |
| strptr += substr_len; |
| } |
| /* Make sure we NULL-terminate */ |
| txt[i].txt[txt[i].length] = '\0'; |
| |
| /* Move on to the next record */ |
| aptr += rr_len; |
| } |
| |
| /* Don't lose memory in the next iteration */ |
| free (rr_name); |
| rr_name = NULL; |
| } |
| |
| if (hostname) |
| free (hostname); |
| if (rr_name) |
| free (rr_name); |
| |
| /* clean up on error */ |
| if (status != ARES_SUCCESS) |
| { |
| for (i = 0; i < ancount; i++) |
| { |
| if (txt[i].txt) |
| free (txt[i].txt); |
| } |
| return status; |
| } |
| |
| /* everything looks fine, return the data */ |
| *txt_out = txt; |
| *ntxtreply = ancount; |
| |
| return ARES_SUCCESS; |
| } |