Vlad Dinulescu added ares_parse_ns_reply()

  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

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      \

 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

                       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);

.\"

.\" 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

/* 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;

}