aboutsummaryrefslogtreecommitdiffstats
path: root/packet-udp.c
blob: 4bb565712116770dd1156455b240da7c8b7a1391 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
/* packet-udp.c
 * Routines for UDP packet disassembly
 *
 * $Id: packet-udp.c,v 1.99 2001/12/08 06:41:42 guy Exp $
 *
 * Ethereal - Network traffic analyzer
 * By Gerald Combs <gerald@ethereal.com>
 * Copyright 1998 Gerald Combs
 *
 * Richard Sharpe, 13-Feb-1999, added dispatch table support and 
 *                              support for tftp.
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
 
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif

#ifdef HAVE_NETINET_IN_H
# include <netinet/in.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <glib.h>
#include "packet.h"
#include "resolv.h"
#include "ipproto.h"
#include "in_cksum.h"
#include "prefs.h"

#include "packet-udp.h"

#include "packet-ip.h"
#include "conversation.h"

static int proto_udp = -1;		
static int hf_udp_srcport = -1;
static int hf_udp_dstport = -1;
static int hf_udp_port = -1;
static int hf_udp_length = -1;
static int hf_udp_checksum = -1;
static int hf_udp_checksum_bad = -1;

static gint ett_udp = -1;

/* Place UDP summary in proto tree */
static gboolean udp_summary_in_tree = TRUE;

/* UDP structs and definitions */

typedef struct _e_udphdr {
  guint16 uh_sport;
  guint16 uh_dport;
  guint16 uh_ulen;
  guint16 uh_sum;
} e_udphdr;

static dissector_table_t udp_dissector_table;
static heur_dissector_list_t heur_subdissector_list;
static dissector_handle_t data_handle;

/* Determine if there is a sub-dissector and call it.  This has been */
/* separated into a stand alone routine to other protocol dissectors */
/* can call to it, ie. socks	*/

void
decode_udp_ports(tvbuff_t *tvb, int offset, packet_info *pinfo,
	proto_tree *tree, int uh_sport, int uh_dport)
{
  tvbuff_t *next_tvb;

  next_tvb = tvb_new_subset(tvb, offset, -1, -1);

/* determine if this packet is part of a conversation and call dissector */
/* for the conversation if available */

  if (try_conversation_dissector(&pinfo->src, &pinfo->dst, PT_UDP,
		uh_sport, uh_dport, next_tvb, pinfo, tree))
    return;

  /* do lookup with the subdissector table */
  if (dissector_try_port(udp_dissector_table, uh_sport, next_tvb, pinfo, tree) ||
      dissector_try_port(udp_dissector_table, uh_dport, next_tvb, pinfo, tree))
    return;

  /* do lookup with the heuristic subdissector table */
  if (dissector_try_heuristic(heur_subdissector_list, next_tvb, pinfo, tree))
    return;

  call_dissector(data_handle,next_tvb, pinfo, tree);
}


static void
dissect_udp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
  e_udphdr  uh;
  guint16    uh_sport, uh_dport, uh_ulen, uh_sum;
  proto_tree *udp_tree;
  proto_item *ti;
  guint      len;
  guint      reported_len;
  vec_t      cksum_vec[4];
  guint32    phdr[2];
  guint16    computed_cksum;
  int        offset = 0;

  if (check_col(pinfo->fd, COL_PROTOCOL))
    col_set_str(pinfo->fd, COL_PROTOCOL, "UDP");
  if (check_col(pinfo->fd, COL_INFO))
    col_clear(pinfo->fd, COL_INFO);

  /* Avoids alignment problems on many architectures. */
  tvb_memcpy(tvb, (guint8 *)&uh, offset, sizeof(e_udphdr));
  uh_sport = ntohs(uh.uh_sport);
  uh_dport = ntohs(uh.uh_dport);
  uh_ulen  = ntohs(uh.uh_ulen);
  uh_sum   = ntohs(uh.uh_sum);
  
  if (check_col(pinfo->fd, COL_INFO))
    col_add_fstr(pinfo->fd, COL_INFO, "Source port: %s  Destination port: %s",
	    get_udp_port(uh_sport), get_udp_port(uh_dport));
    
  if (tree) {
    if (udp_summary_in_tree) {
      ti = proto_tree_add_protocol_format(tree, proto_udp, tvb, offset, 8,
      "User Datagram Protocol, Src Port: %s (%u), Dst Port: %s (%u)",
      get_udp_port(uh_sport), uh_sport, get_udp_port(uh_dport), uh_dport);
    } else {
      ti = proto_tree_add_item(tree, proto_udp, tvb, offset, 8, FALSE);
    }
    udp_tree = proto_item_add_subtree(ti, ett_udp);

    proto_tree_add_uint_format(udp_tree, hf_udp_srcport, tvb, offset, 2, uh_sport,
	"Source port: %s (%u)", get_udp_port(uh_sport), uh_sport);
    proto_tree_add_uint_format(udp_tree, hf_udp_dstport, tvb, offset + 2, 2, uh_dport,
	"Destination port: %s (%u)", get_udp_port(uh_dport), uh_dport);

    proto_tree_add_uint_hidden(udp_tree, hf_udp_port, tvb, offset, 2, uh_sport);
    proto_tree_add_uint_hidden(udp_tree, hf_udp_port, tvb, offset+2, 2, uh_dport);

    proto_tree_add_uint(udp_tree, hf_udp_length, tvb, offset + 4, 2,  uh_ulen);
    reported_len = tvb_reported_length(tvb);
    len = tvb_length(tvb);
    if (uh_sum == 0) {
      /* No checksum supplied in the packet. */
      proto_tree_add_uint_format(udp_tree, hf_udp_checksum, tvb,
        offset + 6, 2, uh_sum, "Checksum: 0x%04x (none)", uh_sum);
    } else if (!pinfo->fragmented && len >= reported_len && len >= uh_ulen) {
      /* The packet isn't part of a fragmented datagram and isn't
         truncated, so we can checksum it.
	 XXX - make a bigger scatter-gather list once we do fragment
	 reassembly? */

      /* Set up the fields of the pseudo-header. */
      cksum_vec[0].ptr = pinfo->src.data;
      cksum_vec[0].len = pinfo->src.len;
      cksum_vec[1].ptr = pinfo->dst.data;
      cksum_vec[1].len = pinfo->dst.len;
      cksum_vec[2].ptr = (const guint8 *)&phdr;
      switch (pinfo->src.type) {

      case AT_IPv4:
	phdr[0] = htonl((IP_PROTO_UDP<<16) + reported_len);
	cksum_vec[2].len = 4;
	break;

      case AT_IPv6:
        phdr[0] = htonl(reported_len);
        phdr[1] = htonl(IP_PROTO_UDP);
        cksum_vec[2].len = 8;
        break;

      default:
        /* TCP runs only atop IPv4 and IPv6.... */
        g_assert_not_reached();
        break;
      }
      cksum_vec[3].ptr = tvb_get_ptr(tvb, offset, len);
      cksum_vec[3].len = reported_len;
      computed_cksum = in_cksum(&cksum_vec[0], 4);
      if (computed_cksum == 0) {
        proto_tree_add_uint_format(udp_tree, hf_udp_checksum, tvb,
          offset + 6, 2, uh_sum, "Checksum: 0x%04x (correct)", uh_sum);
      } else {
	proto_tree_add_boolean_hidden(udp_tree, hf_udp_checksum_bad, tvb,
	   offset + 6, 2, TRUE);
        proto_tree_add_uint_format(udp_tree, hf_udp_checksum, tvb,
          offset + 6, 2, uh_sum,
	  "Checksum: 0x%04x (incorrect, should be 0x%04x)", uh_sum,
	   in_cksum_shouldbe(uh_sum, computed_cksum));
      }
    } else {
      proto_tree_add_uint_format(udp_tree, hf_udp_checksum, tvb,
        offset + 6, 2, uh_sum, "Checksum: 0x%04x", uh_sum);
    }
  }

  /* Skip over header */
  offset += 8;

  pinfo->ptype = PT_UDP;
  pinfo->srcport = uh_sport;
  pinfo->destport = uh_dport;

/* call sub-dissectors */
  decode_udp_ports( tvb, offset, pinfo, tree, uh_sport, uh_dport);

}

void
proto_register_udp(void)
{
	module_t *udp_module;
	static hf_register_info hf[] = {
		{ &hf_udp_srcport,
		{ "Source Port",	"udp.srcport", FT_UINT16, BASE_DEC, NULL, 0x0,
			"", HFILL }},

		{ &hf_udp_dstport,
		{ "Destination Port",	"udp.dstport", FT_UINT16, BASE_DEC, NULL, 0x0,
			"", HFILL }},

		{ &hf_udp_port,
		{ "Source or Destination Port",	"udp.port", FT_UINT16, BASE_DEC,  NULL, 0x0,
			"", HFILL }},

		{ &hf_udp_length,
		{ "Length",		"udp.length", FT_UINT16, BASE_DEC, NULL, 0x0,
			"", HFILL }},

		{ &hf_udp_checksum_bad,
		{ "Bad Checksum",	"udp.checksum_bad", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
			"", HFILL }},

		{ &hf_udp_checksum,
		{ "Checksum",		"udp.checksum", FT_UINT16, BASE_HEX, NULL, 0x0,
			"", HFILL }},
	};
	static gint *ett[] = {
		&ett_udp,
	};

	proto_udp = proto_register_protocol("User Datagram Protocol",
	    "UDP", "udp");
	proto_register_field_array(proto_udp, hf, array_length(hf));
	proto_register_subtree_array(ett, array_length(ett));

/* subdissector code */
	udp_dissector_table = register_dissector_table("udp.port",
	    "UDP port", FT_UINT16, BASE_DEC);
	register_heur_dissector_list("udp", &heur_subdissector_list);
	
	/* Register configuration preferences */
	udp_module = prefs_register_protocol(proto_udp, NULL);
	prefs_register_bool_preference(udp_module, "udp_summary_in_tree",
	"Show UDP summary in protocol treee", 
	"Whether the UDP summary line should be shown in the protocol tree",
	&udp_summary_in_tree);
}

void
proto_reg_handoff_udp(void)
{
	dissector_handle_t udp_handle;

	udp_handle = create_dissector_handle(dissect_udp, proto_udp);
	dissector_add("ip.proto", IP_PROTO_UDP, udp_handle);
	data_handle = find_dissector("data");
}