testcode/pktview.c

   1 /*
   2  * testcode/pktview.c - debug program to disassemble a DNS packet.
   3  *
   4  * Copyright (c) 2007, NLnet Labs. All rights reserved.
   5  *
   6  * This software is open source.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * Redistributions of source code must retain the above copyright notice,
  13  * this list of conditions and the following disclaimer.
  14  *
  15  * Redistributions in binary form must reproduce the above copyright notice,
  16  * this list of conditions and the following disclaimer in the documentation
  17  * and/or other materials provided with the distribution.
  18  *
  19  * Neither the name of the NLNET LABS nor the names of its contributors may
  20  * be used to endorse or promote products derived from this software without
  21  * specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  24  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  25  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  26  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  27  * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  28  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
  29  * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  30  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  31  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  32  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  33  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34  */
  35
  36 /**
  37  * \file
  38  *
  39  * This program shows a dns packet wire format.
  40  */
  41
  42 #include "config.h"
  43 #include "util/log.h"
  44 #include "util/data/dname.h"
  45 #include "util/data/msgparse.h"
  46 #include "testcode/unitmain.h"
  47 #include "testcode/readhex.h"
  48 #include "sldns/sbuffer.h"
  49 #include "sldns/parseutil.h"
  50
  51 /** usage information for pktview */
  52 static void usage(char* argv[])
  53 {
  54         printf("usage: %s\n", argv[0]);
  55         printf("present hex packet on stdin.\n");
  56         exit(1);
  57 }
  58
  59 /** read hex input */
  60 static void read_input(sldns_buffer* pkt, FILE* in)
  61 {
  62         char buf[102400];
  63         char* np = buf;
  64         while(fgets(np, (int)sizeof(buf) - (np-buf), in)) {
  65                 if(buf[0] == ';') /* comment */
  66                         continue;
  67                 np = &np[strlen(np)];
  68         }
  69         hex_to_buf(pkt, buf);
  70 }
  71
  72 /** analyze domain name in packet, possibly compressed */
  73 static void analyze_dname(sldns_buffer* pkt)
  74 {
  75         size_t oldpos = sldns_buffer_position(pkt);
  76         size_t len;
  77         printf("[pos %d] dname: ", (int)oldpos);
  78         dname_print(stdout, pkt, sldns_buffer_current(pkt));
  79         len = pkt_dname_len(pkt);
  80         printf(" len=%d", (int)len);
  81         if(sldns_buffer_position(pkt)-oldpos != len)
  82                 printf(" comprlen=%d\n",
  83                         (int)(sldns_buffer_position(pkt)-oldpos));
  84         else    printf("\n");
  85 }
  86
  87 /** analyze rdata in packet */
  88 static void analyze_rdata(sldns_buffer*pkt, const sldns_rr_descriptor* desc,
  89         uint16_t rdlen)
  90 {
  91         int rdf = 0;
  92         int count = (int)desc->_dname_count;
  93         size_t len, oldpos;
  94         while(rdlen > 0 && count) {
  95                 switch(desc->_wireformat[rdf]) {
  96                 case LDNS_RDF_TYPE_DNAME:
  97                         oldpos = sldns_buffer_position(pkt);
  98                         analyze_dname(pkt);
  99                         rdlen -= sldns_buffer_position(pkt)-oldpos;
 100                         count --;
 101                         len = 0;
 102                         break;
 103                 case LDNS_RDF_TYPE_STR:
 104                         len = sldns_buffer_current(pkt)[0] + 1;
 105                         break;
 106                 default:
 107                         len = get_rdf_size(desc->_wireformat[rdf]);
 108                 }
 109                 if(len) {
 110                         printf(" wf[%d]", (int)len);
 111                         sldns_buffer_skip(pkt, (ssize_t)len);
 112                         rdlen -= len;
 113                 }
 114                 rdf++;
 115         }
 116         if(rdlen) {
 117                 size_t i;
 118                 printf(" remain[%d]\n", (int)rdlen);
 119                 for(i=0; i<rdlen; i++)
 120                         printf(" %2.2X", (unsigned)sldns_buffer_current(pkt)[i]);
 121                 printf("\n");
 122         }
 123         else    printf("\n");
 124         sldns_buffer_skip(pkt, (ssize_t)rdlen);
 125 }
 126
 127 /** analyze rr in packet */
 128 static void analyze_rr(sldns_buffer* pkt, int q)
 129 {
 130         uint16_t type, dclass, len;
 131         uint32_t ttl;
 132         analyze_dname(pkt);
 133         type = sldns_buffer_read_u16(pkt);
 134         dclass = sldns_buffer_read_u16(pkt);
 135         printf("type %s(%d)", sldns_rr_descript(type)?
 136                 sldns_rr_descript(type)->_name: "??" , (int)type);
 137         printf(" class %s(%d) ", sldns_lookup_by_id(sldns_rr_classes,
 138                 (int)dclass)?sldns_lookup_by_id(sldns_rr_classes,
 139                 (int)dclass)->name:"??", (int)dclass);
 140         if(q) {
 141                 printf("\n");
 142         } else {
 143                 ttl = sldns_buffer_read_u32(pkt);
 144                 printf(" ttl %d (0x%x)", (int)ttl, (unsigned)ttl);
 145                 len = sldns_buffer_read_u16(pkt);
 146                 printf(" rdata len %d:\n", (int)len);
 147                 if(sldns_rr_descript(type))
 148                         analyze_rdata(pkt, sldns_rr_descript(type), len);
 149                 else sldns_buffer_skip(pkt, (ssize_t)len);
 150         }
 151 }
 152
 153 /** analyse pkt */
 154 static void analyze(sldns_buffer* pkt)
 155 {
 156         uint16_t i, f, qd, an, ns, ar;
 157         int rrnum = 0;
 158         printf("packet length %d\n", (int)sldns_buffer_limit(pkt));
 159         if(sldns_buffer_limit(pkt) < 12) return;
 160
 161         i = sldns_buffer_read_u16(pkt);
 162         printf("id (hostorder): %d (0x%x)\n", (int)i, (unsigned)i);
 163         f = sldns_buffer_read_u16(pkt);
 164         printf("flags: 0x%x\n", (unsigned)f);
 165         qd = sldns_buffer_read_u16(pkt);
 166         printf("qdcount: %d\n", (int)qd);
 167         an = sldns_buffer_read_u16(pkt);
 168         printf("ancount: %d\n", (int)an);
 169         ns = sldns_buffer_read_u16(pkt);
 170         printf("nscount: %d\n", (int)ns);
 171         ar = sldns_buffer_read_u16(pkt);
 172         printf("arcount: %d\n", (int)ar);
 173
 174         printf(";-- query section\n");
 175         while(sldns_buffer_remaining(pkt) > 0) {
 176                 if(rrnum == (int)qd)
 177                         printf(";-- answer section\n");
 178                 if(rrnum == (int)qd+(int)an)
 179                         printf(";-- authority section\n");
 180                 if(rrnum == (int)qd+(int)an+(int)ns)
 181                         printf(";-- additional section\n");
 182                 printf("rr %d ", rrnum);
 183                 analyze_rr(pkt, rrnum < (int)qd);
 184                 rrnum++;
 185         }
 186 }
 187
 188 /** main program for pktview */
 189 int main(int argc, char* argv[])
 190 {
 191         sldns_buffer* pkt = sldns_buffer_new(65553);
 192         if(argc != 1) {
 193                 usage(argv);
 194         }
 195         if(!pkt) fatal_exit("out of memory");
 196
 197         read_input(pkt, stdin);
 198         analyze(pkt);
 199
 200         sldns_buffer_free(pkt);
 201         return 0;
 202 }