added ares_parse_mx_reply

7 files changed, 286 insertions, 0 deletions

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 <ares.h>
+.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 <kapouer@melix.org>
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 <kapouer@melix.org>
+ *
+ * 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
+
+#include <stdlib.h>
+#include <string.h>
+#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;
+}