From 63918fca7667a03b310c5f8486636a896be7ac72 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?J=C3=A9r=C3=A9my=20Lal?= Date: Sun, 18 Apr 2010 00:29:26 +0200 Subject: [PATCH] added ares_parse_mx_reply --- Makefile.inc | 4 + ares.h | 10 +++ ares_data.c | 14 ++++ ares_data.h | 2 + ares_free_data.3 | 7 ++ ares_parse_mx_reply.3 | 79 ++++++++++++++++++++ ares_parse_mx_reply.c | 170 ++++++++++++++++++++++++++++++++++++++++++ 7 files changed, 286 insertions(+) create mode 100644 ares_parse_mx_reply.3 create mode 100644 ares_parse_mx_reply.c diff --git a/Makefile.inc b/Makefile.inc index cef828a..bc211f8 100644 --- a/Makefile.inc +++ b/Makefile.inc @@ -23,6 +23,7 @@ CSOURCES = ares__close_sockets.c \ ares_options.c \ ares_parse_a_reply.c \ ares_parse_aaaa_reply.c \ + ares_parse_mx_reply.c \ ares_parse_ns_reply.c \ ares_parse_ptr_reply.c \ ares_parse_srv_reply.c \ @@ -86,6 +87,7 @@ MANPAGES = ares_cancel.3 \ ares_mkquery.3 \ ares_parse_a_reply.3 \ ares_parse_aaaa_reply.3 \ + ares_parse_mx_reply.3 \ ares_parse_ns_reply.3 \ ares_parse_ptr_reply.3 \ ares_parse_srv_reply.3 \ @@ -124,6 +126,7 @@ HTMLPAGES = ares_cancel.html \ ares_mkquery.html \ ares_parse_a_reply.html \ ares_parse_aaaa_reply.html \ + ares_parse_mx_reply.html \ ares_parse_ns_reply.html \ ares_parse_ptr_reply.html \ ares_parse_srv_reply.html \ @@ -162,6 +165,7 @@ PDFPAGES = ares_cancel.pdf \ ares_mkquery.pdf \ ares_parse_a_reply.pdf \ ares_parse_aaaa_reply.pdf \ + ares_parse_mx_reply.pdf \ ares_parse_ns_reply.pdf \ ares_parse_ptr_reply.pdf \ ares_parse_srv_reply.pdf \ diff --git a/ares.h b/ares.h index 31c862a..368c73a 100644 --- a/ares.h +++ b/ares.h @@ -433,6 +433,12 @@ struct ares_srv_reply { unsigned short port; }; +struct ares_mx_reply { + struct ares_mx_reply *next; + char *host; + unsigned short priority; +}; + struct ares_txt_reply { struct ares_txt_reply *next; unsigned char *txt; @@ -474,6 +480,10 @@ CARES_EXTERN int ares_parse_srv_reply(const unsigned char* abuf, int alen, struct ares_srv_reply** srv_out); +CARES_EXTERN int ares_parse_mx_reply(const unsigned char* abuf, + int alen, + struct ares_mx_reply** mx_out); + CARES_EXTERN int ares_parse_txt_reply(const unsigned char* abuf, int alen, struct ares_txt_reply** txt_out); diff --git a/ares_data.c b/ares_data.c index 59fe449..6b6fae8 100644 --- a/ares_data.c +++ b/ares_data.c @@ -62,6 +62,14 @@ void ares_free_data(void *dataptr) switch (ptr->type) { + case ARES_DATATYPE_MX_REPLY: + + if (ptr->data.mx_reply.next) + ares_free_data(ptr->data.mx_reply.next); + if (ptr->data.mx_reply.host) + free(ptr->data.mx_reply.host); + break; + case ARES_DATATYPE_SRV_REPLY: if (ptr->data.srv_reply.next) @@ -113,6 +121,12 @@ void *ares_malloc_data(ares_datatype type) switch (type) { + case ARES_DATATYPE_MX_REPLY: + ptr->data.mx_reply.next = NULL; + ptr->data.mx_reply.host = NULL; + ptr->data.mx_reply.priority = 0; + break; + case ARES_DATATYPE_SRV_REPLY: ptr->data.srv_reply.next = NULL; ptr->data.srv_reply.host = NULL; diff --git a/ares_data.h b/ares_data.h index 193c179..de1608b 100644 --- a/ares_data.h +++ b/ares_data.h @@ -19,6 +19,7 @@ typedef enum { ARES_DATATYPE_SRV_REPLY, /* struct ares_srv_reply - introduced in 1.7.0 */ ARES_DATATYPE_TXT_REPLY, /* struct ares_txt_reply - introduced in 1.7.0 */ ARES_DATATYPE_ADDR_NODE, /* struct ares_addr_node - introduced in 1.7.1 */ + ARES_DATATYPE_MX_REPLY, /* struct ares_mx_reply - introduced in 1.7.2 */ #if 0 ARES_DATATYPE_ADDR6TTL, /* struct ares_addrttl */ ARES_DATATYPE_ADDRTTL, /* struct ares_addr6ttl */ @@ -55,6 +56,7 @@ struct ares_data { struct ares_txt_reply txt_reply; struct ares_srv_reply srv_reply; struct ares_addr_node addr_node; + struct ares_mx_reply mx_reply; } data; }; diff --git a/ares_free_data.3 b/ares_free_data.3 index b783fd0..c6cadd5 100644 --- a/ares_free_data.3 +++ b/ares_free_data.3 @@ -44,6 +44,12 @@ will free the whole linked list of ares_srv_reply structures returned by ares_parse_srv_reply(3), along with any additional storage associated with those structures. .TP +.B ares_parse_mx_reply(3) +When used to free the data returned by ares_parse_mx_reply(3) this +will free the whole linked list of ares_mx_reply structures returned +by ares_parse_mx_reply(3), along with any additional storage +associated with those structures. +.TP .B ares_parse_txt_reply(3) When used to free the data returned by ares_parse_txt_reply(3) this will free the whole linked list of ares_txt_reply structures returned @@ -56,6 +62,7 @@ This function was first introduced in c-ares version 1.7.0. .SH SEE ALSO .BR ares_get_servers(3), .BR ares_parse_srv_reply(3), +.BR ares_parse_mx_reply(3), .BR ares_parse_txt_reply(3) .SH AUTHOR Yang Tse diff --git a/ares_parse_mx_reply.3 b/ares_parse_mx_reply.3 new file mode 100644 index 0000000..87df459 --- /dev/null +++ b/ares_parse_mx_reply.3 @@ -0,0 +1,79 @@ +.\" +.\" 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_MX_REPLY 3 "4 August 2009" +.SH NAME +ares_parse_mx_reply \- Parse a reply to a DNS query of type MX +.SH SYNOPSIS +.nf +.B #include +.PP +.B int ares_parse_mx_reply(const unsigned char* \fIabuf\fP, int \fIalen\fP, +.B struct ares_mx_reply** \fImx_out\fP); +.fi +.SH DESCRIPTION +The +.B ares_parse_mx_reply +function parses the response to a query of type MX into a +linked list of +.I struct ares_mx_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 mx_out . +It is the caller's responsibility to free the resulting +.IR mx_out +structure when it is no longer needed using the function +.B ares_free_data +.PP +The structure +.I ares_mx_reply +contains the following fields: +.sp +.in +4n +.nf +struct ares_mx_reply { + struct ares_mx_reply *next; + char *host; + unsigned short priority; +}; +.fi +.in +.PP +.SH RETURN VALUES +.B ares_parse_mx_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 AVAILABILITY +This function was first introduced in c-ares version 1.7.2. +.SH SEE ALSO +.BR ares_query (3) +.BR ares_free_data (3) +.SH AUTHOR +Written by Jeremy Lal diff --git a/ares_parse_mx_reply.c b/ares_parse_mx_reply.c new file mode 100644 index 0000000..186ddd3 --- /dev/null +++ b/ares_parse_mx_reply.c @@ -0,0 +1,170 @@ + +/* Copyright 1998 by the Massachusetts Institute of Technology. + * Copyright (C) 2010 Jeremy Lal + * + * 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 +#endif +#ifdef HAVE_NETINET_IN_H +# include +#endif +#ifdef HAVE_NETDB_H +# include +#endif +#ifdef HAVE_ARPA_INET_H +# include +#endif +#ifdef HAVE_ARPA_NAMESER_H +# include +#else +# include "nameser.h" +#endif +#ifdef HAVE_ARPA_NAMESER_COMPAT_H +# include +#endif + +#include +#include +#include "ares.h" +#include "ares_dns.h" +#include "ares_data.h" +#include "ares_private.h" + +int +ares_parse_mx_reply (const unsigned char *abuf, int alen, + struct ares_mx_reply **mx_out) +{ + unsigned int qdcount, ancount, i; + const unsigned char *aptr, *vptr; + int status, rr_type, rr_class, rr_len; + long len; + char *hostname = NULL, *rr_name = NULL; + struct ares_mx_reply *mx_head = NULL; + struct ares_mx_reply *mx_last = NULL; + struct ares_mx_reply *mx_curr; + + /* Set *mx_out to NULL for all failure cases. */ + *mx_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; + + /* 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 MX record */ + if (rr_class == C_IN && rr_type == T_MX) + { + /* parse the MX record itself */ + if (rr_len < 2) + { + status = ARES_EBADRESP; + break; + } + + /* Allocate storage for this MX answer appending it to the list */ + mx_curr = ares_malloc_data(ARES_DATATYPE_MX_REPLY); + if (!mx_curr) + { + status = ARES_ENOMEM; + break; + } + if (mx_last) + { + mx_last->next = mx_curr; + } + else + { + mx_head = mx_curr; + } + mx_last = mx_curr; + + vptr = aptr; + mx_curr->priority = ntohs (*((unsigned short *)vptr)); + vptr += sizeof(unsigned short); + + status = ares_expand_name (vptr, abuf, alen, &mx_curr->host, &len); + if (status != ARES_SUCCESS) + break; + } + + /* Don't lose memory in the next iteration */ + free (rr_name); + rr_name = NULL; + + /* Move on to the next record */ + aptr += rr_len; + } + + if (hostname) + free (hostname); + if (rr_name) + free (rr_name); + + /* clean up on error */ + if (status != ARES_SUCCESS) + { + if (mx_head) + ares_free_data (mx_head); + return status; + } + + /* everything looks fine, return the data */ + *mx_out = mx_head; + + return ARES_SUCCESS; +}