* $Id: libnet_build_dns.c,v 1.20 2005/11/29 22:29:57 carlosc Exp $
* libnet_build_dns.c - DNS packet assembler
* Copyright (c) 1998 - 2004 Mike D. Schiffman <mike@infonexus.com>
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
#include "../include/config.h"
#if (!(_WIN32) || (__CYGWIN__))
#include "../include/libnet.h"
#include "../include/win32/libnet.h"
libnet_build_dnsv4(u_int16_t h_len
, u_int16_t id
, u_int16_t flags
,
u_int16_t num_q
, u_int16_t num_anws_rr
, u_int16_t num_auth_rr
,
u_int16_t num_addi_rr
, u_int8_t
*payload
, u_int32_t payload_s
,
libnet_t
*l
, libnet_ptag_t ptag
)
struct libnet_dnsv4_hdr dns_hdr
;
if (h_len
!= LIBNET_UDP_DNSV4_H
&& h_len
!= LIBNET_TCP_DNSV4_H
)
snprintf(l
->err_buf
, LIBNET_ERRBUF_SIZE
,
"%s(): invalid header length: %d", __func__
, h_len
);
offset
= (h_len
== LIBNET_UDP_DNSV4_H
? sizeof(dns_hdr
.h_len
) : 0);
* Find the existing protocol block if a ptag is specified, or create
p
= libnet_pblock_probe(l
, ptag
, n
, LIBNET_PBLOCK_DNSV4_H
);
* The sizeof(dns_hdr.h_len) is not counted is the packet size
* And since this will be ignored for udp packets, let's compute it
memset(&dns_hdr
, 0, sizeof(dns_hdr
));
dns_hdr
.h_len
= htons(n
- sizeof (dns_hdr
.h_len
));
dns_hdr
.flags
= htons(flags
);
dns_hdr
.num_q
= htons(num_q
);
dns_hdr
.num_answ_rr
= htons(num_anws_rr
);
dns_hdr
.num_auth_rr
= htons(num_auth_rr
);
dns_hdr
.num_addi_rr
= htons(num_addi_rr
);
* A dirty trick: DNS can be either TCP or UDP based, and depending on
* that, the header changes. A 'length' field is present in TCP packets,
* but not in UDP packets. As they are the first 2 bytes of the header,
* they are skipped if the packet is UDP...
n
= libnet_pblock_append(l
, p
, ((u_int8_t
*)&dns_hdr
)+ offset
, h_len
);
if ((payload
&& !payload_s
) || (!payload
&& payload_s
))
snprintf(l
->err_buf
, LIBNET_ERRBUF_SIZE
,
"%s(): payload inconsistency\n", __func__
);
if (payload
&& payload_s
)
n
= libnet_pblock_append(l
, p
, payload
, payload_s
);
return (ptag
? ptag
: libnet_pblock_update(l
, p
, h
, LIBNET_PBLOCK_DNSV4_H
));
libnet_pblock_delete(l
, p
);