GopherProxy

/*
* testcode/pktview.c - debug program to disassemble a DNS packet.
*
* Copyright (c) 2007, NLnet Labs. All rights reserved.
*
* This software is open source.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 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.
*
* Neither the name of the NLNET LABS nor the names of its contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
* HOLDER 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 SUCH DAMAGE.
*/

/**
* \file
*
* This program shows a dns packet wire format.
*/

#include "config.h"
#include "util/log.h"
#include "util/data/dname.h"
#include "util/data/msgparse.h"
#include "testcode/unitmain.h"
#include "testcode/readhex.h"
#include "sldns/sbuffer.h"
#include "sldns/parseutil.h"

/** usage information for pktview */
static void usage(char* argv[])
{
printf("usage: %s\n", argv[0]);
printf("present hex packet on stdin.\n");
exit(1);
}

/** read hex input */
static void read_input(sldns_buffer* pkt, FILE* in)
{
char buf[102400];
char* np = buf;
while(fgets(np, (int)sizeof(buf) - (np-buf), in)) {
if(buf[0] == ';') /* comment */
continue;
np = &np[strlen(np)];
}
hex_to_buf(pkt, buf);
}

/** analyze domain name in packet, possibly compressed */
static void analyze_dname(sldns_buffer* pkt)
{
size_t oldpos = sldns_buffer_position(pkt);
size_t len;
printf("[pos %d] dname: ", (int)oldpos);
dname_print(stdout, pkt, sldns_buffer_current(pkt));
len = pkt_dname_len(pkt);
printf(" len=%d", (int)len);
if(sldns_buffer_position(pkt)-oldpos != len)
printf(" comprlen=%d\n",
(int)(sldns_buffer_position(pkt)-oldpos));
else printf("\n");
}

/** analyze rdata in packet */
static void analyze_rdata(sldns_buffer*pkt, const sldns_rr_descriptor* desc,
uint16_t rdlen)
{
int rdf = 0;
int count = (int)desc->_dname_count;
size_t len, oldpos;
while(rdlen > 0 && count) {
switch(desc->_wireformat[rdf]) {
case LDNS_RDF_TYPE_DNAME:
oldpos = sldns_buffer_position(pkt);
analyze_dname(pkt);
rdlen -= sldns_buffer_position(pkt)-oldpos;
count --;
len = 0;
break;
case LDNS_RDF_TYPE_STR:
len = sldns_buffer_current(pkt)[0] + 1;
break;
default:
len = get_rdf_size(desc->_wireformat[rdf]);
}
if(len) {
printf(" wf[%d]", (int)len);
sldns_buffer_skip(pkt, (ssize_t)len);
rdlen -= len;
}
rdf++;
}
if(rdlen) {
size_t i;
printf(" remain[%d]\n", (int)rdlen);
for(i=0; i<rdlen; i++)
printf(" %2.2X", (unsigned)sldns_buffer_current(pkt)[i]);
printf("\n");
}
else printf("\n");
sldns_buffer_skip(pkt, (ssize_t)rdlen);
}

/** analyze rr in packet */
static void analyze_rr(sldns_buffer* pkt, int q)
{
uint16_t type, dclass, len;
uint32_t ttl;
analyze_dname(pkt);
type = sldns_buffer_read_u16(pkt);
dclass = sldns_buffer_read_u16(pkt);
printf("type %s(%d)", sldns_rr_descript(type)?
sldns_rr_descript(type)->_name: "??" , (int)type);
printf(" class %s(%d) ", sldns_lookup_by_id(sldns_rr_classes,
(int)dclass)?sldns_lookup_by_id(sldns_rr_classes,
(int)dclass)->name:"??", (int)dclass);
if(q) {
printf("\n");
} else {
ttl = sldns_buffer_read_u32(pkt);
printf(" ttl %d (0x%x)", (int)ttl, (unsigned)ttl);
len = sldns_buffer_read_u16(pkt);
printf(" rdata len %d:\n", (int)len);
if(sldns_rr_descript(type))
analyze_rdata(pkt, sldns_rr_descript(type), len);
else sldns_buffer_skip(pkt, (ssize_t)len);
}
}

/** analyse pkt */
static void analyze(sldns_buffer* pkt)
{
uint16_t i, f, qd, an, ns, ar;
int rrnum = 0;
printf("packet length %d\n", (int)sldns_buffer_limit(pkt));
if(sldns_buffer_limit(pkt) < 12) return;

i = sldns_buffer_read_u16(pkt);
printf("id (hostorder): %d (0x%x)\n", (int)i, (unsigned)i);
f = sldns_buffer_read_u16(pkt);
printf("flags: 0x%x\n", (unsigned)f);
qd = sldns_buffer_read_u16(pkt);
printf("qdcount: %d\n", (int)qd);
an = sldns_buffer_read_u16(pkt);
printf("ancount: %d\n", (int)an);
ns = sldns_buffer_read_u16(pkt);
printf("nscount: %d\n", (int)ns);
ar = sldns_buffer_read_u16(pkt);
printf("arcount: %d\n", (int)ar);

printf(";-- query section\n");
while(sldns_buffer_remaining(pkt) > 0) {
if(rrnum == (int)qd)
printf(";-- answer section\n");
if(rrnum == (int)qd+(int)an)
printf(";-- authority section\n");
if(rrnum == (int)qd+(int)an+(int)ns)
printf(";-- additional section\n");
printf("rr %d ", rrnum);
analyze_rr(pkt, rrnum < (int)qd);
rrnum++;
}
}

/** main program for pktview */
int main(int argc, char* argv[])
{
sldns_buffer* pkt = sldns_buffer_new(65553);
if(argc != 1) {
usage(argv);
}
if(!pkt) fatal_exit("out of memory");

read_input(pkt, stdin);
analyze(pkt);

sldns_buffer_free(pkt);
return 0;
}