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 */
usage(char * argv[])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 */
read_input(sldns_buffer * pkt,FILE * in)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 */
analyze_dname(sldns_buffer * pkt)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 */
analyze_rdata(sldns_buffer * pkt,const sldns_rr_descriptor * desc,uint16_t rdlen)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 */
analyze_rr(sldns_buffer * pkt,int q)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 */
analyze(sldns_buffer * 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 */
main(int argc,char * argv[])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 }
203