diff options
| -rw-r--r-- | CHANGES | 3 | ||||
| -rw-r--r-- | Makefile.inc | 2 | ||||
| -rw-r--r-- | RELEASE-NOTES | 3 | ||||
| -rw-r--r-- | ares.h | 10 | ||||
| -rw-r--r-- | ares_parse_txt_reply.3 | 77 | ||||
| -rw-r--r-- | ares_parse_txt_reply.c | 176 |
6 files changed, 270 insertions, 1 deletions
@@ -1,5 +1,8 @@ Changelog for the c-ares project +* October 29, 2009 (Daniel Stenberg) +- Jakub Hrozek added ares_parse_txt_reply() for TXT parsing + * October 23, 2009 (Yang Tse) - John Engelhart noticed an unreleased problem relative to a duplicate ARES_ECANCELLED error code value and missing error code description. diff --git a/Makefile.inc b/Makefile.inc index 13e6214..1fe1129 100644 --- a/Makefile.inc +++ b/Makefile.inc @@ -23,6 +23,8 @@ CSOURCES = ares__close_sockets.c \ ares_parse_ns_reply.c \ ares_parse_ptr_reply.c \ ares_parse_srv_reply.c \ + ares_parse_txt_reply.c \ + ares_free_txt_reply.c \ ares_process.c \ ares_query.c \ ares_search.c \ diff --git a/RELEASE-NOTES b/RELEASE-NOTES index 52c6c29..68a5d3b 100644 --- a/RELEASE-NOTES +++ b/RELEASE-NOTES @@ -1,4 +1,4 @@ -This is what's new and changed in the c-ares 1.6.1 release: +This is what's new and changed in the c-ares 1.7.0 release: Changed: @@ -11,6 +11,7 @@ Changed: o new --enable-curldebug configure option o ARES_ECANCELLED is now sent as reason for ares_cancel() o added ares_parse_srv_reply() + o added ares_parse_txt_reply() Fixed: @@ -436,6 +436,11 @@ struct ares_srv_reply { char *host; }; +struct ares_txt_reply { + unsigned int length; + unsigned char *txt; +}; + /* ** Parse the buffer, starting at *abuf and of length alen bytes, previously ** obtained from an ares_search call. Put the results in *host, if nonnull. @@ -472,6 +477,11 @@ CARES_EXTERN int ares_parse_srv_reply(const unsigned char* abuf, struct ares_srv_reply** srv_out, int *nsrvreply); +CARES_EXTERN int ares_parse_txt_reply(const unsigned char* abuf, + int alen, + struct ares_txt_reply** txt_out, + int *nsrvreply); + CARES_EXTERN void ares_free_string(void *str); CARES_EXTERN void ares_free_hostent(struct hostent *host); diff --git a/ares_parse_txt_reply.3 b/ares_parse_txt_reply.3 new file mode 100644 index 0000000..2d65edb --- /dev/null +++ b/ares_parse_txt_reply.3 @@ -0,0 +1,77 @@ +.\" +.\" Copyright 1998 by the Massachusetts Institute of Technology. +.\" +.\" 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. +.\" +.TH ARES_PARSE_TXT_REPLY 3 "27 October 2009" +.SH NAME +ares_parse_txt_reply \- Parse a reply to a DNS query of type TXT into a +struct ares_txt_reply +.SH SYNOPSIS +.nf +.B #include <ares.h> +.PP +.B int ares_parse_txt_reply(const unsigned char* \fIabuf\fP, int \fIalen\fP, +.B struct ares_txt_reply **\fItxt_out\fP, int *\fIntxtreply\fP); +.fi +.SH DESCRIPTION +The +.B ares_parse_txt_reply +function parses the response to a query of type TXT into a +.I struct ares_txt_reply +The parameters +.I abuf +and +.I alen +give the contents of the response. The result is stored in allocated +memory and a pointer to it stored into the variable pointed to by +.IR txt_out . +The number of responses is stored into the variable pointed to by +.IR ntxtreply . +It is the caller's responsibility to free the resulting +.IR txt_out +structure when it is no longer needed. +.PP +The structure +.I ares_txt_reply +contains the following fields: +.sp +.in +4n +.nf +struct ares_txt_reply { + unsigned int length; + unsigned char *txt; +}; +.fi +.in +.PP +.SH RETURN VALUES +.B ares_parse_txt_reply +can return any of the following values: +.TP 15 +.B ARES_SUCCESS +The response was successfully parsed. +.TP 15 +.B ARES_EBADRESP +The response was malformatted. +.TP 15 +.B ARES_ENODATA +The response did not contain an answer to the query. +.TP 15 +.B ARES_ENOMEM +Memory was exhausted. +.SH SEE ALSO +.BR ares_query (3) +.SH AUTHOR +Written by Jakub Hrozek <jhrozek@redhat.com>, on behalf of Red Hat, Inc http://www.redhat.com + diff --git a/ares_parse_txt_reply.c b/ares_parse_txt_reply.c new file mode 100644 index 0000000..c99ee72 --- /dev/null +++ b/ares_parse_txt_reply.c @@ -0,0 +1,176 @@ +/* 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; +} |