forked from osmocom/wireshark
3a583aeb59
include of <resolv.h> in any system header file gets the system <resolv.h> (needed for builds on Tru64 with GTK+ 1.2[.x]). svn path=/trunk/; revision=11615
357 lines
12 KiB
C
357 lines
12 KiB
C
/* packet-udp.c
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* Routines for UDP packet disassembly
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*
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* $Id$
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@ethereal.com>
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* Copyright 1998 Gerald Combs
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*
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* Richard Sharpe, 13-Feb-1999, added dispatch table support and
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* support for tftp.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <glib.h>
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#include <epan/packet.h>
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#include <epan/addr_resolv.h>
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#include "ipproto.h"
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#include "in_cksum.h"
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#include "prefs.h"
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#include "packet-udp.h"
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#include "packet-ip.h"
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#include <epan/conversation.h>
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#include "tap.h"
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static int udp_tap = -1;
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static int proto_udp = -1;
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static int hf_udp_srcport = -1;
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static int hf_udp_dstport = -1;
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static int hf_udp_port = -1;
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static int hf_udp_length = -1;
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static int hf_udp_checksum = -1;
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static int hf_udp_checksum_bad = -1;
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static gint ett_udp = -1;
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/* Place UDP summary in proto tree */
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static gboolean udp_summary_in_tree = TRUE;
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static dissector_table_t udp_dissector_table;
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static heur_dissector_list_t heur_subdissector_list;
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static dissector_handle_t data_handle;
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/* Determine if there is a sub-dissector and call it. This has been */
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/* separated into a stand alone routine to other protocol dissectors */
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/* can call to it, ie. socks */
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static gboolean try_heuristic_first = FALSE;
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void
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decode_udp_ports(tvbuff_t *tvb, int offset, packet_info *pinfo,
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proto_tree *tree, int uh_sport, int uh_dport, int uh_ulen)
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{
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tvbuff_t *next_tvb;
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int low_port, high_port;
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gint len, reported_len;
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len = tvb_length_remaining(tvb, offset);
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reported_len = tvb_reported_length_remaining(tvb, offset);
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if (uh_ulen != -1) {
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/* This is the length from the UDP header; the payload should be cut
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off at that length.
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XXX - what if it's *greater* than the reported length? */
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if (uh_ulen < len)
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len = uh_ulen;
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if (uh_ulen < reported_len)
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reported_len = uh_ulen;
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}
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next_tvb = tvb_new_subset(tvb, offset, len, reported_len);
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/* determine if this packet is part of a conversation and call dissector */
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/* for the conversation if available */
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if (try_conversation_dissector(&pinfo->src, &pinfo->dst, PT_UDP,
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uh_sport, uh_dport, next_tvb, pinfo, tree))
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return;
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if (try_heuristic_first) {
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/* do lookup with the heuristic subdissector table */
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if (dissector_try_heuristic(heur_subdissector_list, next_tvb, pinfo, tree))
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return;
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}
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/* Do lookups with the subdissector table.
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We try the port number with the lower value first, followed by the
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port number with the higher value. This means that, for packets
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where a dissector is registered for *both* port numbers:
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1) we pick the same dissector for traffic going in both directions;
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2) we prefer the port number that's more likely to be the right
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one (as that prefers well-known ports to reserved ports);
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although there is, of course, no guarantee that any such strategy
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will always pick the right port number.
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XXX - we ignore port numbers of 0, as some dissectors use a port
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number of 0 to disable the port, and as RFC 768 says that the source
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port in UDP datagrams is optional and is 0 if not used. */
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if (uh_sport > uh_dport) {
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low_port = uh_dport;
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high_port = uh_sport;
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} else {
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low_port = uh_sport;
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high_port = uh_dport;
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}
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if (low_port != 0 &&
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dissector_try_port(udp_dissector_table, low_port, next_tvb, pinfo, tree))
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return;
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if (high_port != 0 &&
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dissector_try_port(udp_dissector_table, high_port, next_tvb, pinfo, tree))
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return;
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if (!try_heuristic_first) {
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/* do lookup with the heuristic subdissector table */
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if (dissector_try_heuristic(heur_subdissector_list, next_tvb, pinfo, tree))
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return;
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}
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call_dissector(data_handle,next_tvb, pinfo, tree);
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}
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static void
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dissect_udp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
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{
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proto_tree *udp_tree;
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proto_item *ti;
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guint len;
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guint reported_len;
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vec_t cksum_vec[4];
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guint32 phdr[2];
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guint16 computed_cksum;
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int offset = 0;
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static e_udphdr udphstruct[4], *udph;
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static int udph_count=0;
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udph_count++;
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if(udph_count>=4){
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udph_count=0;
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}
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udph=&udphstruct[udph_count];
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SET_ADDRESS(&udph->ip_src, pinfo->src.type, pinfo->src.len, pinfo->src.data);
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SET_ADDRESS(&udph->ip_dst, pinfo->dst.type, pinfo->dst.len, pinfo->dst.data);
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if (check_col(pinfo->cinfo, COL_PROTOCOL))
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "UDP");
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if (check_col(pinfo->cinfo, COL_INFO))
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col_clear(pinfo->cinfo, COL_INFO);
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udph->uh_sport=tvb_get_ntohs(tvb, offset);
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udph->uh_dport=tvb_get_ntohs(tvb, offset+2);
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udph->uh_ulen=tvb_get_ntohs(tvb, offset+4);
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udph->uh_sum=tvb_get_ntohs(tvb, offset+6);
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if (check_col(pinfo->cinfo, COL_INFO))
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col_add_fstr(pinfo->cinfo, COL_INFO, "Source port: %s Destination port: %s",
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get_udp_port(udph->uh_sport), get_udp_port(udph->uh_dport));
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if (tree) {
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if (udp_summary_in_tree) {
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ti = proto_tree_add_protocol_format(tree, proto_udp, tvb, offset, 8,
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"User Datagram Protocol, Src Port: %s (%u), Dst Port: %s (%u)",
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get_udp_port(udph->uh_sport), udph->uh_sport, get_udp_port(udph->uh_dport), udph->uh_dport);
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} else {
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ti = proto_tree_add_item(tree, proto_udp, tvb, offset, 8, FALSE);
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}
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udp_tree = proto_item_add_subtree(ti, ett_udp);
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proto_tree_add_uint_format(udp_tree, hf_udp_srcport, tvb, offset, 2, udph->uh_sport,
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"Source port: %s (%u)", get_udp_port(udph->uh_sport), udph->uh_sport);
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proto_tree_add_uint_format(udp_tree, hf_udp_dstport, tvb, offset + 2, 2, udph->uh_dport,
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"Destination port: %s (%u)", get_udp_port(udph->uh_dport), udph->uh_dport);
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proto_tree_add_uint_hidden(udp_tree, hf_udp_port, tvb, offset, 2, udph->uh_sport);
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proto_tree_add_uint_hidden(udp_tree, hf_udp_port, tvb, offset+2, 2, udph->uh_dport);
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if (udph->uh_ulen < 8) {
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/* Bogus length - it includes the header, so it must be >= 8. */
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proto_tree_add_uint_format(udp_tree, hf_udp_length, tvb, offset + 4, 2,
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udph->uh_ulen, "Length: %u (bogus, must be >= 8)", udph->uh_ulen);
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return;
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}
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proto_tree_add_uint(udp_tree, hf_udp_length, tvb, offset + 4, 2, udph->uh_ulen);
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reported_len = tvb_reported_length(tvb);
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len = tvb_length(tvb);
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if (udph->uh_sum == 0) {
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/* No checksum supplied in the packet. */
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proto_tree_add_uint_format(udp_tree, hf_udp_checksum, tvb,
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offset + 6, 2, udph->uh_sum, "Checksum: 0x%04x (none)", udph->uh_sum);
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} else if (!pinfo->fragmented && len >= reported_len &&
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len >= udph->uh_ulen && reported_len >= udph->uh_ulen) {
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/* The packet isn't part of a fragmented datagram and isn't
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truncated, so we can checksum it.
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XXX - make a bigger scatter-gather list once we do fragment
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reassembly? */
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/* Set up the fields of the pseudo-header. */
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cksum_vec[0].ptr = pinfo->src.data;
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cksum_vec[0].len = pinfo->src.len;
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cksum_vec[1].ptr = pinfo->dst.data;
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cksum_vec[1].len = pinfo->dst.len;
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cksum_vec[2].ptr = (const guint8 *)&phdr;
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switch (pinfo->src.type) {
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case AT_IPv4:
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phdr[0] = g_htonl((IP_PROTO_UDP<<16) + udph->uh_ulen);
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cksum_vec[2].len = 4;
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break;
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case AT_IPv6:
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phdr[0] = g_htonl(udph->uh_ulen);
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phdr[1] = g_htonl(IP_PROTO_UDP);
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cksum_vec[2].len = 8;
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break;
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default:
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/* TCP runs only atop IPv4 and IPv6.... */
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g_assert_not_reached();
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break;
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}
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cksum_vec[3].ptr = tvb_get_ptr(tvb, offset, udph->uh_ulen);
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cksum_vec[3].len = udph->uh_ulen;
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computed_cksum = in_cksum(&cksum_vec[0], 4);
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if (computed_cksum == 0) {
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proto_tree_add_uint_format(udp_tree, hf_udp_checksum, tvb,
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offset + 6, 2, udph->uh_sum, "Checksum: 0x%04x (correct)", udph->uh_sum);
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} else {
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proto_tree_add_boolean_hidden(udp_tree, hf_udp_checksum_bad, tvb,
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offset + 6, 2, TRUE);
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proto_tree_add_uint_format(udp_tree, hf_udp_checksum, tvb,
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offset + 6, 2, udph->uh_sum,
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"Checksum: 0x%04x (incorrect, should be 0x%04x)", udph->uh_sum,
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in_cksum_shouldbe(udph->uh_sum, computed_cksum));
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}
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} else {
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proto_tree_add_uint_format(udp_tree, hf_udp_checksum, tvb,
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offset + 6, 2, udph->uh_sum, "Checksum: 0x%04x", udph->uh_sum);
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}
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}
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/* Skip over header */
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offset += 8;
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pinfo->ptype = PT_UDP;
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pinfo->srcport = udph->uh_sport;
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pinfo->destport = udph->uh_dport;
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tap_queue_packet(udp_tap, pinfo, udph);
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/*
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* Call sub-dissectors.
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*
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* XXX - should we do this if this is included in an error packet?
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* It might be nice to see the details of the packet that caused the
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* ICMP error, but it might not be nice to have the dissector update
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* state based on it.
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* Also, we probably don't want to run UDP taps on those packets.
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*
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* We definitely don't want to do it for an error packet if there's
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* nothing left in the packet.
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*/
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if (!pinfo->in_error_pkt || tvb_length_remaining(tvb, offset) > 0)
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decode_udp_ports(tvb, offset, pinfo, tree, udph->uh_sport, udph->uh_dport,
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udph->uh_ulen);
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}
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void
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proto_register_udp(void)
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{
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module_t *udp_module;
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static hf_register_info hf[] = {
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{ &hf_udp_srcport,
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{ "Source Port", "udp.srcport", FT_UINT16, BASE_DEC, NULL, 0x0,
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"", HFILL }},
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{ &hf_udp_dstport,
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{ "Destination Port", "udp.dstport", FT_UINT16, BASE_DEC, NULL, 0x0,
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"", HFILL }},
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{ &hf_udp_port,
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{ "Source or Destination Port", "udp.port", FT_UINT16, BASE_DEC, NULL, 0x0,
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"", HFILL }},
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{ &hf_udp_length,
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{ "Length", "udp.length", FT_UINT16, BASE_DEC, NULL, 0x0,
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"", HFILL }},
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{ &hf_udp_checksum_bad,
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{ "Bad Checksum", "udp.checksum_bad", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
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"", HFILL }},
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{ &hf_udp_checksum,
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{ "Checksum", "udp.checksum", FT_UINT16, BASE_HEX, NULL, 0x0,
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"", HFILL }},
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};
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static gint *ett[] = {
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&ett_udp,
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};
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proto_udp = proto_register_protocol("User Datagram Protocol",
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"UDP", "udp");
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proto_register_field_array(proto_udp, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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/* subdissector code */
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udp_dissector_table = register_dissector_table("udp.port",
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"UDP port", FT_UINT16, BASE_DEC);
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register_heur_dissector_list("udp", &heur_subdissector_list);
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/* Register configuration preferences */
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udp_module = prefs_register_protocol(proto_udp, NULL);
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prefs_register_bool_preference(udp_module, "summary_in_tree",
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"Show UDP summary in protocol tree",
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"Whether the UDP summary line should be shown in the protocol tree",
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&udp_summary_in_tree);
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prefs_register_bool_preference(udp_module, "try_heuristic_first",
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"Try heuristic sub-dissectors first",
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"Try to decode a packet using an heuristic sub-dissector before using a sub-dissector registered to a specific port",
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&try_heuristic_first);
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}
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void
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proto_reg_handoff_udp(void)
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{
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dissector_handle_t udp_handle;
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udp_handle = create_dissector_handle(dissect_udp, proto_udp);
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dissector_add("ip.proto", IP_PROTO_UDP, udp_handle);
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data_handle = find_dissector("data");
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udp_tap = register_tap("udp");
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}
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