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-rw-r--r--epan/dissectors/packet-udp.c356
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diff --git a/epan/dissectors/packet-udp.c b/epan/dissectors/packet-udp.c
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+/* packet-udp.c
+ * Routines for UDP packet disassembly
+ *
+ * $Id$
+ *
+ * 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
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <glib.h>
+#include <epan/packet.h>
+#include <epan/resolv.h>
+#include "ipproto.h"
+#include "in_cksum.h"
+#include "prefs.h"
+
+#include "packet-udp.h"
+
+#include "packet-ip.h"
+#include <epan/conversation.h>
+#include "tap.h"
+
+static int udp_tap = -1;
+
+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;
+
+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 */
+
+static gboolean try_heuristic_first = FALSE;
+
+void
+decode_udp_ports(tvbuff_t *tvb, int offset, packet_info *pinfo,
+ proto_tree *tree, int uh_sport, int uh_dport, int uh_ulen)
+{
+ tvbuff_t *next_tvb;
+ int low_port, high_port;
+ gint len, reported_len;
+
+ len = tvb_length_remaining(tvb, offset);
+ reported_len = tvb_reported_length_remaining(tvb, offset);
+ if (uh_ulen != -1) {
+ /* This is the length from the UDP header; the payload should be cut
+ off at that length.
+ XXX - what if it's *greater* than the reported length? */
+ if (uh_ulen < len)
+ len = uh_ulen;
+ if (uh_ulen < reported_len)
+ reported_len = uh_ulen;
+ }
+ next_tvb = tvb_new_subset(tvb, offset, len, reported_len);
+
+/* 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;
+
+ if (try_heuristic_first) {
+ /* do lookup with the heuristic subdissector table */
+ if (dissector_try_heuristic(heur_subdissector_list, next_tvb, pinfo, tree))
+ return;
+ }
+
+ /* Do lookups with the subdissector table.
+ We try the port number with the lower value first, followed by the
+ port number with the higher value. This means that, for packets
+ where a dissector is registered for *both* port numbers:
+
+ 1) we pick the same dissector for traffic going in both directions;
+
+ 2) we prefer the port number that's more likely to be the right
+ one (as that prefers well-known ports to reserved ports);
+
+ although there is, of course, no guarantee that any such strategy
+ will always pick the right port number.
+
+ XXX - we ignore port numbers of 0, as some dissectors use a port
+ number of 0 to disable the port, and as RFC 768 says that the source
+ port in UDP datagrams is optional and is 0 if not used. */
+ if (uh_sport > uh_dport) {
+ low_port = uh_dport;
+ high_port = uh_sport;
+ } else {
+ low_port = uh_sport;
+ high_port = uh_dport;
+ }
+ if (low_port != 0 &&
+ dissector_try_port(udp_dissector_table, low_port, next_tvb, pinfo, tree))
+ return;
+ if (high_port != 0 &&
+ dissector_try_port(udp_dissector_table, high_port, next_tvb, pinfo, tree))
+ return;
+
+ if (!try_heuristic_first) {
+ /* 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)
+{
+ 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;
+ static e_udphdr udphstruct[4], *udph;
+ static int udph_count=0;
+
+ udph_count++;
+ if(udph_count>=4){
+ udph_count=0;
+ }
+ udph=&udphstruct[udph_count];
+ SET_ADDRESS(&udph->ip_src, pinfo->src.type, pinfo->src.len, pinfo->src.data);
+ SET_ADDRESS(&udph->ip_dst, pinfo->dst.type, pinfo->dst.len, pinfo->dst.data);
+
+ if (check_col(pinfo->cinfo, COL_PROTOCOL))
+ col_set_str(pinfo->cinfo, COL_PROTOCOL, "UDP");
+ if (check_col(pinfo->cinfo, COL_INFO))
+ col_clear(pinfo->cinfo, COL_INFO);
+
+ udph->uh_sport=tvb_get_ntohs(tvb, offset);
+ udph->uh_dport=tvb_get_ntohs(tvb, offset+2);
+ udph->uh_ulen=tvb_get_ntohs(tvb, offset+4);
+ udph->uh_sum=tvb_get_ntohs(tvb, offset+6);
+
+
+ if (check_col(pinfo->cinfo, COL_INFO))
+ col_add_fstr(pinfo->cinfo, COL_INFO, "Source port: %s Destination port: %s",
+ get_udp_port(udph->uh_sport), get_udp_port(udph->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(udph->uh_sport), udph->uh_sport, get_udp_port(udph->uh_dport), udph->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, udph->uh_sport,
+ "Source port: %s (%u)", get_udp_port(udph->uh_sport), udph->uh_sport);
+ proto_tree_add_uint_format(udp_tree, hf_udp_dstport, tvb, offset + 2, 2, udph->uh_dport,
+ "Destination port: %s (%u)", get_udp_port(udph->uh_dport), udph->uh_dport);
+
+ proto_tree_add_uint_hidden(udp_tree, hf_udp_port, tvb, offset, 2, udph->uh_sport);
+ proto_tree_add_uint_hidden(udp_tree, hf_udp_port, tvb, offset+2, 2, udph->uh_dport);
+
+ if (udph->uh_ulen < 8) {
+ /* Bogus length - it includes the header, so it must be >= 8. */
+ proto_tree_add_uint_format(udp_tree, hf_udp_length, tvb, offset + 4, 2,
+ udph->uh_ulen, "Length: %u (bogus, must be >= 8)", udph->uh_ulen);
+ return;
+ }
+ proto_tree_add_uint(udp_tree, hf_udp_length, tvb, offset + 4, 2, udph->uh_ulen);
+ reported_len = tvb_reported_length(tvb);
+ len = tvb_length(tvb);
+ if (udph->uh_sum == 0) {
+ /* No checksum supplied in the packet. */
+ proto_tree_add_uint_format(udp_tree, hf_udp_checksum, tvb,
+ offset + 6, 2, udph->uh_sum, "Checksum: 0x%04x (none)", udph->uh_sum);
+ } else if (!pinfo->fragmented && len >= reported_len &&
+ len >= udph->uh_ulen && reported_len >= udph->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] = g_htonl((IP_PROTO_UDP<<16) + udph->uh_ulen);
+ cksum_vec[2].len = 4;
+ break;
+
+ case AT_IPv6:
+ phdr[0] = g_htonl(udph->uh_ulen);
+ phdr[1] = g_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, udph->uh_ulen);
+ cksum_vec[3].len = udph->uh_ulen;
+ 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, udph->uh_sum, "Checksum: 0x%04x (correct)", udph->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, udph->uh_sum,
+ "Checksum: 0x%04x (incorrect, should be 0x%04x)", udph->uh_sum,
+ in_cksum_shouldbe(udph->uh_sum, computed_cksum));
+ }
+ } else {
+ proto_tree_add_uint_format(udp_tree, hf_udp_checksum, tvb,
+ offset + 6, 2, udph->uh_sum, "Checksum: 0x%04x", udph->uh_sum);
+ }
+ }
+
+ /* Skip over header */
+ offset += 8;
+
+ pinfo->ptype = PT_UDP;
+ pinfo->srcport = udph->uh_sport;
+ pinfo->destport = udph->uh_dport;
+
+ tap_queue_packet(udp_tap, pinfo, udph);
+ /*
+ * Call sub-dissectors.
+ *
+ * XXX - should we do this if this is included in an error packet?
+ * It might be nice to see the details of the packet that caused the
+ * ICMP error, but it might not be nice to have the dissector update
+ * state based on it.
+ * Also, we probably don't want to run UDP taps on those packets.
+ *
+ * We definitely don't want to do it for an error packet if there's
+ * nothing left in the packet.
+ */
+ if (!pinfo->in_error_pkt || tvb_length_remaining(tvb, offset) > 0)
+ decode_udp_ports(tvb, offset, pinfo, tree, udph->uh_sport, udph->uh_dport,
+ udph->uh_ulen);
+}
+
+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, "summary_in_tree",
+ "Show UDP summary in protocol tree",
+ "Whether the UDP summary line should be shown in the protocol tree",
+ &udp_summary_in_tree);
+ prefs_register_bool_preference(udp_module, "try_heuristic_first",
+ "Try heuristic sub-dissectors first",
+ "Try to decode a packet using an heuristic sub-dissector before using a sub-dissector registered to a specific port",
+ &try_heuristic_first);
+}
+
+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");
+ udp_tap = register_tap("udp");
+}
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