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authorDaniel Stenberg <daniel@haxx.se>2009-10-29 08:59:40 (GMT)
committerDaniel Stenberg <daniel@haxx.se>2009-10-29 08:59:40 (GMT)
commit9cbd5ed0346c027db16fdc8a0c091d69aa79607b (patch)
treee9c29466ca24b8fc389314afcf4c4ced3b67964a /ares_parse_txt_reply.c
parent9ff3cb7411dc659bddd0c8a37ea07c3737a74664 (diff)
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Jakub Hrozek added ares_parse_txt_reply() for TXT parsing
Diffstat (limited to 'ares_parse_txt_reply.c')
-rw-r--r--ares_parse_txt_reply.c176
1 files changed, 176 insertions, 0 deletions
diff --git a/ares_parse_txt_reply.c b/ares_parse_txt_reply.c
new file mode 100644
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+++ b/ares_parse_txt_reply.c
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+/* Copyright (C) 2009 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 "setup.h"
+
+#if defined(WIN32) && !defined(WATT32)
+#include "nameser.h"
+#else
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+#include <arpa/nameser.h>
+#ifdef HAVE_ARPA_NAMESER_COMPAT_H
+#include <arpa/nameser_compat.h>
+#endif
+#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)
+{
+ unsigned char substr_len = 0;
+ unsigned char str_len = 0;
+ unsigned int qdcount, ancount;
+ const unsigned char *aptr;
+ const unsigned char *strptr;
+ int status, i, rr_type, rr_class, rr_len;
+ long len;
+ char *hostname = NULL, *rr_name = NULL;
+ struct ares_txt_reply *txt = NULL;
+
+ *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)
+ {
+ 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;
+ }
+ /* Zero out so we can safely free txt.txt even if NULL */
+ memset(txt, 0, ancount * sizeof (struct ares_txt_reply));
+
+ /* Examine each answer resource record (RR) in turn. */
+ for (i = 0; i < (int) 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.
+ */
+
+ /* Realloc would be expensive, compute the total length */
+ txt[i].length = 0;
+ strptr = aptr;
+ while (strptr < (aptr + rr_len))
+ {
+ memcpy ((void *) &substr_len, strptr, sizeof (unsigned char));
+ txt[i].length += substr_len;
+ strptr += substr_len + 1;
+ }
+
+ /* Including null byte */
+ txt[i].txt = malloc (sizeof (unsigned char) * (txt[i].length + 1));
+ if (txt[i].txt == NULL)
+ {
+ status = ARES_ENOMEM;
+ break;
+ }
+
+ /* Step through the list of substrings, concatenating them */
+ substr_len = 0;
+ str_len = 0;
+ strptr = aptr;
+ while (strptr < (aptr + rr_len))
+ {
+ memcpy ((void *) &substr_len, strptr, sizeof (unsigned char));
+ strptr++;
+ memcpy ((void *) txt[i].txt + str_len, strptr,
+ sizeof (unsigned char) * 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;
+ }
+
+ free (hostname);
+ free (rr_name);
+
+ /* clean up on error */
+ if (status != ARES_SUCCESS)
+ {
+ ares_free_txt_reply(txt, ancount);
+ return status;
+ }
+
+ /* everything looks fine, return the data */
+ *txt_out = txt;
+ *ntxtreply = ancount;
+ return 0;
+}