Vlad Dinulescu added ares_parse_ns_reply()

CHANGES

@@ -1,5 +1,9 @@
   Changelog for the c-ares project
 
+* February 19
+
+- Vlad Dinulescu added ares_parse_ns_reply().
+
 * February 13
 
 - Yang Tse: Fix failure to get the search sequence of /etc/hosts and

Makefile.inc

@@ -5,17 +5,18 @@ ares_gethostbyname.c ares_strerror.c ares_cancel.c ares_init.c		\
 ares_timeout.c ares_destroy.c ares_mkquery.c ares_version.c		\
 ares_expand_name.c ares_parse_a_reply.c windows_port.c			\
 ares_expand_string.c ares_parse_ptr_reply.c ares_parse_aaaa_reply.c	\
-ares_getnameinfo.c inet_net_pton.c bitncmp.c inet_ntop.c
+ares_getnameinfo.c inet_net_pton.c bitncmp.c inet_ntop.c		\
+ares_parse_ns_reply.c
 
 HHEADERS = ares.h ares_private.h setup.h ares_dns.h ares_version.h          \
            nameser.h inet_net_pton.h inet_ntop.h ares_ipv6.h bitncmp.h      \
            setup_once.h 
 
 MANPAGES= ares_destroy.3 ares_expand_name.3 ares_expand_string.3 ares_fds.3 \
- ares_free_hostent.3 ares_free_string.3 ares_gethostbyaddr.3                \
- ares_gethostbyname.3 ares_init.3 ares_init_options.3 ares_mkquery.3        \
- ares_parse_a_reply.3 ares_parse_ptr_reply.3 ares_process.3                 \
- ares_query.3 ares_search.3 ares_send.3 ares_strerror.3 ares_timeout.3      \
+ ares_free_hostent.3 ares_free_string.3 ares_gethostbyaddr.3		    \
+ ares_gethostbyname.3 ares_init.3 ares_init_options.3 ares_mkquery.3	    \
+ ares_parse_a_reply.3 ares_parse_ptr_reply.3 ares_process.3		    \
+ ares_query.3 ares_search.3 ares_send.3 ares_strerror.3 ares_timeout.3	    \
  ares_version.3 ares_cancel.3 ares_parse_aaaa_reply.3 ares_getnameinfo.3    \
- ares_getsock.3
+ ares_getsock.3 ares_parse_ns_reply.3
 

ares.h

@@ -213,6 +213,8 @@ int ares_parse_aaaa_reply(const unsigned char *abuf, int alen,
                        struct hostent **host);
 int ares_parse_ptr_reply(const unsigned char *abuf, int alen, const void *addr,
                          int addrlen, int family, struct hostent **host);
+int ares_parse_ns_reply(const unsigned char *abuf, int alen,
+                       struct hostent **host);
 void ares_free_string(void *str);
 void ares_free_hostent(struct hostent *host);
 const char *ares_strerror(int code);

ares_parse_ns_reply.3

@@ -0,0 +1,66 @@
+.\"
+.\" 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_NS_REPLY 3 "10 February 2007"
+.SH NAME
+ares_parse_ns_reply \- Parse a reply to a DNS query of type NS into a hostent
+.SH SYNOPSIS
+.nf
+.B #include <ares.h>
+.PP
+.B int ares_parse_ns_reply(const unsigned char *\fIabuf\fP, int \fIalen\fP,
+.B 	struct hostent **\fIhost\fP);
+.fi
+.SH DESCRIPTION
+The
+.B ares_parse_ns_reply
+function parses the response to a query of type NS into a
+.BR "struct hostent" .
+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 host . 
+The nameservers are stored into the 
+.BR aliases 
+field of the 
+.IR host 
+structure. 
+It is the caller's responsibility to free the resulting host structure
+using
+.BR ares_free_hostent (3)
+when it is no longer needed.
+.SH RETURN VALUES
+.B ares_parse_ns_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),
+.BR ares_free_hostent (3)
+.SH AUTHOR
+Written by Vlad Dinulescu <vlad.dinulescu@avira.com>, on behalf of AVIRA Gmbh http://www.avira.com

ares_parse_ns_reply.c

@@ -0,0 +1,172 @@
+/* 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.
+ */
+
+/*
+ * ares_parse_ns_reply created by Vlad Dinulescu <vlad.dinulescu@avira.com>
+ *      on behalf of AVIRA Gmbh - http://www.avira.com
+ */
+
+#include "setup.h"
+#include <sys/types.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_ns_reply( const unsigned char* abuf, int alen,
+                         struct hostent** host )
+{
+  unsigned int qdcount, ancount;
+  int status, i, rr_type, rr_class, rr_len;
+  int nameservers_num;
+  long len;
+  const unsigned char *aptr;
+  char* hostname, *rr_name, *rr_data, **nameservers;
+  struct hostent *hostent;
+
+  /* Set *host to NULL for all failure cases. */
+  *host = 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;
+
+  /* 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 nameservers array; ancount gives an upper bound */
+  nameservers = malloc( ( ancount + 1 ) * sizeof( char * ) );
+  if ( !nameservers )
+  {
+    free( hostname );
+    return ARES_ENOMEM;
+  }
+  nameservers_num = 0;
+
+  /* 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;
+
+    if ( rr_class == C_IN && rr_type == T_NS )
+    {
+      /* Decode the RR data and add it to the nameservers list */
+      status = ares_expand_name( aptr, abuf, alen, &rr_data, &len );
+      if ( status != ARES_SUCCESS )
+      {
+        break;
+      }
+
+      nameservers[nameservers_num] = malloc(strlen(rr_data)+1);
+
+      if (nameservers[nameservers_num]==NULL)
+      {
+        free(rr_name);
+        free(rr_data);
+        status=ARES_ENOMEM;
+        break;
+      }
+      strcpy(nameservers[nameservers_num],rr_data);
+      free(rr_data);
+
+      nameservers_num++;
+    }
+
+    free( rr_name );
+
+    aptr += rr_len;
+    if ( aptr > abuf + alen )
+    {
+      status = ARES_EBADRESP;
+      break;
+    }
+  }
+
+  if ( status == ARES_SUCCESS && nameservers_num == 0 )
+  {
+    status = ARES_ENODATA;
+  }
+  if ( status == ARES_SUCCESS )
+  {
+    /* We got our answer.  Allocate memory to build the host entry. */
+    nameservers[nameservers_num] = NULL;
+    hostent = malloc( sizeof( struct hostent ) );
+    if ( hostent )
+    {
+      hostent->h_addr_list = malloc( 1 * sizeof( char * ) );
+      if ( hostent->h_addr_list )
+      {
+        /* Fill in the hostent and return successfully. */
+        hostent->h_name = hostname;
+        hostent->h_aliases = nameservers;
+        hostent->h_addrtype = AF_INET;
+        hostent->h_length = sizeof( struct in_addr );
+        hostent->h_addr_list[0] = NULL;
+        *host = hostent;
+        return ARES_SUCCESS;
+      }
+      free( hostent );
+    }
+    status = ARES_ENOMEM;
+  }
+  for ( i = 0; i < nameservers_num; i++ )
+    free( nameservers[i] );
+  free( nameservers );
+  free( hostname );
+  return status;
+}