wireshark/epan/dissectors/packet-teredo.c

/* packet-teredo.c  v.1.0
 * Routines for Teredo packets disassembly
 *   draft-huitema-v6ops-teredo-02.txt
 *
 * Copyright 2003, Ragi BEJJANI - 6WIND - <ragi.bejjani@6wind.com>
 * Copyright 2003, Vincent JARDIN - 6WIND - <vincent.jardin@6wind.com>
 * Copyright 2004, Remi DENIS-COURMONT
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#include "config.h"

#include <epan/packet.h>
#include <epan/prefs.h>

#include <epan/tap.h>

#define UDP_PORT_TEREDO 3544

void proto_reg_handoff_teredo(void);
void proto_register_teredo(void);

static int teredo_tap = -1;

static int proto_teredo = -1;

static int hf_teredo_auth = -1;
static int hf_teredo_auth_idlen = -1;
static int hf_teredo_auth_aulen = -1;
static int hf_teredo_auth_id = -1;
static int hf_teredo_auth_value = -1;
static int hf_teredo_auth_nonce = -1;
static int hf_teredo_auth_conf = -1;
static int hf_teredo_orig = -1;
static int hf_teredo_orig_port = -1;
static int hf_teredo_orig_addr = -1;

static gint ett_teredo = -1;
static gint ett_teredo_auth = -1, ett_teredo_orig = -1;

typedef struct {
	guint16 th_indtyp;
	guint8 th_cidlen;
	guint8 th_authdlen;
	guint8 th_nonce[8];
	guint8 th_conf;

	guint8 th_ip_v_hl;
	guint16 th_header;
	guint16 th_orgport;
	guint32 th_iporgaddr;
} e_teredohdr;

static dissector_table_t teredo_dissector_table;
/*static heur_dissector_list_t heur_subdissector_list;*/
static dissector_handle_t teredo_handle;
static dissector_handle_t data_handle;

static int
parse_teredo_auth(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
			int offset, e_teredohdr *teredoh)
{
	guint idlen, aulen;

	col_append_sep_str (pinfo->cinfo, COL_INFO, ", ",
					"Authentication header");

	teredoh->th_indtyp = 1;
	offset += 2;

	idlen = tvb_get_guint8(tvb, offset);
	teredoh->th_cidlen = idlen;
	offset++;

	aulen = tvb_get_guint8(tvb, offset);
	teredoh->th_authdlen = aulen;
	offset++;

	if (tree) {
		proto_item *ti;

		ti = proto_tree_add_item(tree, hf_teredo_auth, tvb, offset-4,
						13 + idlen + aulen, ENC_NA);
		tree = proto_item_add_subtree(ti, ett_teredo_auth);

		proto_tree_add_item(tree, hf_teredo_auth_idlen, tvb,
					offset - 2, 1, ENC_BIG_ENDIAN);
		proto_tree_add_item(tree, hf_teredo_auth_aulen, tvb,
					offset - 1, 1, ENC_BIG_ENDIAN);

		/* idlen is usually zero */
		if (idlen) {
			proto_tree_add_item(tree, hf_teredo_auth_id, tvb,
						offset, idlen, ENC_NA);
			offset += idlen;
		}

		/* aulen is usually zero */
		if (aulen) {
			proto_tree_add_item(tree, hf_teredo_auth_value, tvb,
						offset, aulen, ENC_NA);
			offset += aulen;
		}

		proto_tree_add_item(tree, hf_teredo_auth_nonce, tvb,
					offset, 8, ENC_NA);
		offset += 8;

		proto_tree_add_item(tree, hf_teredo_auth_conf, tvb,
					offset, 1, ENC_NA);
		offset++;
	}
	else
		offset += idlen + aulen + 9;

	tvb_memcpy(tvb, teredoh->th_nonce, offset - 9, 8);
	teredoh->th_conf = tvb_get_guint8(tvb, offset - 1);

	return offset;
}


static int
parse_teredo_orig(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
			int offset, e_teredohdr *teredoh)
{
	proto_item *ti = NULL;

	col_append_sep_str (pinfo->cinfo, COL_INFO, ", ",
					"Origin indication");

	if (tree) {
		ti = proto_tree_add_item(tree, hf_teredo_orig, tvb, offset,
						8, ENC_NA);
		tree = proto_item_add_subtree(ti, ett_teredo_orig);
	}
	offset += 2;

	teredoh->th_orgport = tvb_get_ntohs(tvb, offset);
	if (tree) {
		/*
		 * The "usual arithmetic conversions" will convert
		 * "teredoh->th_orgport" to an "int" (because all
		 * "unsigned short" values will fit in an "int"),
		 * which will zero-extend it.  This means that
		 * complementing it will turn all the zeroes in
		 * the upper 16 bits into ones; we just want the
		 * lower 16 bits (containing the port number)
		 * complemented, with the result zero-extended.
		 *
		 * That's what the cast is for.
		 */
		proto_tree_add_uint(tree, hf_teredo_orig_port, tvb,
					offset, 2,
					(guint16)~teredoh->th_orgport);
	}
	offset += 2;

	teredoh->th_iporgaddr = tvb_get_ipv4(tvb, offset);
	if (tree) {
		proto_tree_add_ipv4(tree, hf_teredo_orig_addr, tvb,
					offset, 4, ~teredoh->th_iporgaddr);
	}
	offset += 4;

	return offset;
}


/* 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 void
decode_teredo_ports(tvbuff_t *tvb, int offset, packet_info *pinfo,proto_tree *tree, int th_header)
{
	tvbuff_t *next_tvb;

	next_tvb = tvb_new_subset_remaining(tvb, offset);

	if (dissector_try_uint(teredo_dissector_table, th_header, next_tvb, pinfo, tree))
		return;

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

static int
dissect_teredo(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
	proto_tree *teredo_tree;
	proto_item *ti;
	int        offset = 0;
	static e_teredohdr teredohstruct[4], *teredoh;
	static int teredoh_count = 0;

	teredoh_count++;
	if(teredoh_count>=4){
		teredoh_count=0;
	}
	teredoh = &teredohstruct[teredoh_count];

	col_set_str(pinfo->cinfo, COL_PROTOCOL, "Teredo");
	col_clear(pinfo->cinfo, COL_INFO);

	ti = proto_tree_add_item(tree, proto_teredo, tvb, 0, -1, ENC_NA);
	teredo_tree = proto_item_add_subtree(ti, ett_teredo);

	teredoh->th_header  = tvb_get_ntohs(tvb, offset);

	if (teredoh->th_header == 1) {
		offset = parse_teredo_auth(tvb, pinfo, teredo_tree,
						offset, teredoh);
		teredoh->th_header  = tvb_get_ntohs(tvb, offset);
	}
	else
		teredoh->th_indtyp  = 0;

	if ( teredoh->th_header == 0 ) {
		offset = parse_teredo_orig(tvb, pinfo, teredo_tree,
						offset, teredoh);
	}

	teredoh->th_ip_v_hl = tvb_get_guint8(tvb, offset);

	decode_teredo_ports(tvb, offset, pinfo, tree, teredoh->th_header /* , teredoh->th_orgport*/);
	tap_queue_packet(teredo_tap, pinfo, teredoh);
	return tvb_captured_length(tvb);
}


static gboolean
dissect_teredo_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
	guint16 val;
	int offset = 0;

	if (tvb_captured_length_remaining(tvb, offset) < 40)
		return FALSE;

	val = tvb_get_ntohs(tvb, offset);

	if (val == 1) /* possible auth header */
	{
		guint8 idlen, aulen;

		offset += 2;

		idlen = tvb_get_guint8(tvb, offset);
		offset++;

		aulen = tvb_get_guint8(tvb, offset);
		offset += 10;

		if (tvb_captured_length_remaining(tvb, offset) < idlen + aulen + 40)
			return FALSE;

		offset += idlen + aulen;

		val = tvb_get_ntohs(tvb, offset);
	}

	if (val == 0) /* origin indication */
	{
		offset += 8;

		if (tvb_captured_length_remaining(tvb, offset) < 40)
			return FALSE;

		val = tvb_get_ntohs(tvb, offset);
	}

	/*
	 * We have to check upper-layer packet a little bit otherwise we will
	 * match -almost- *ANY* packet.
	 * These checks are in the Teredo specification by the way.
	 * Unfortunately, that will cause false-negative if the snaplen is too
	 * short to get the packet entirely.
	 */
	if ((val >> 12) == 6) /* IPv6 header */
	{
		/* checks IPv6 payload length */
		val = tvb_get_ntohs(tvb, offset + 4);
		offset += 40;

		if (val > 65467)
			return FALSE; /* length too big for Teredo */

		if (tvb_reported_length_remaining(tvb, offset) != val)
			return FALSE; /* length mismatch */

		dissect_teredo (tvb, pinfo, tree, data);
		return TRUE;
	}

	return FALSE; /* not an IPv6 packet */
}


void
proto_register_teredo(void)
{
	static hf_register_info hf[] = {
		/* Authentication header */
		{ &hf_teredo_auth,
		{ "Teredo Authentication header", "teredo.auth",
		  FT_NONE, BASE_NONE, NULL, 0x0,
		  NULL, HFILL }},

		{ &hf_teredo_auth_idlen,
		{ "Client identifier length", "teredo.auth.idlen",
		  FT_UINT8, BASE_DEC, NULL, 0x0,
		  "Client identifier length (ID-len)", HFILL }},

		{ &hf_teredo_auth_aulen,
		{ "Authentication value length", "teredo.auth.aulen",
		  FT_UINT8, BASE_DEC, NULL, 0x0,
		  "Authentication value length (AU-len)", HFILL }},

		{ &hf_teredo_auth_id,
		{ "Client identifier", "teredo.auth.id",
		  FT_BYTES, BASE_NONE, NULL, 0x0,
		  "Client identifier (ID)", HFILL }},

		{ &hf_teredo_auth_value,
		{ "Authentication value", "teredo.auth.value",
		  FT_BYTES, BASE_NONE, NULL, 0x0,
		  "Authentication value (hash)", HFILL }},

		{ &hf_teredo_auth_nonce,
		{ "Nonce value", "teredo.auth.nonce",
		  FT_BYTES, BASE_NONE, NULL, 0x0,
		  "Nonce value prevents spoofing Teredo server.",
		  HFILL }},

		{ &hf_teredo_auth_conf,
		{ "Confirmation byte", "teredo.auth.conf",
		  FT_BYTES, BASE_NONE, NULL, 0x0,
		  "Confirmation byte is zero upon successful authentication.",
		  HFILL }},

		/* Origin indication */
		{ &hf_teredo_orig,
		{ "Teredo Origin Indication header", "teredo.orig",
		  FT_NONE, BASE_NONE, NULL, 0x0,
		  "Teredo Origin Indication", HFILL }},

		{ &hf_teredo_orig_port,
		{ "Origin UDP port", "teredo.orig.port",
		  FT_UINT16, BASE_DEC, NULL, 0x0,
		  NULL, HFILL }},

		{ &hf_teredo_orig_addr,
		{ "Origin IPv4 address", "teredo.orig.addr",
		  FT_IPv4, BASE_NONE, NULL, 0x0,
		  NULL, HFILL }},
	};

	static gint *ett[] = {
		&ett_teredo, &ett_teredo_auth, &ett_teredo_orig
	};

	module_t *teredo_module;

	proto_teredo = proto_register_protocol(
		"Teredo IPv6 over UDP tunneling", "Teredo", "teredo");
	proto_register_field_array(proto_teredo, hf, array_length(hf));
	proto_register_subtree_array(ett, array_length(ett));
	teredo_handle = register_dissector("teredo", dissect_teredo, proto_teredo);

/* subdissector code */
	teredo_dissector_table = register_dissector_table("teredo", "Teredo", proto_teredo, FT_UINT16, BASE_DEC);

	teredo_module = prefs_register_protocol(proto_teredo, NULL);

	prefs_register_obsolete_preference(teredo_module, "heuristic_teredo");

}

void
proto_reg_handoff_teredo(void)
{
	data_handle   = find_dissector("ipv6");
	teredo_tap    = register_tap("teredo");

	dissector_add_uint_with_preference("udp.port", UDP_PORT_TEREDO, teredo_handle);
	heur_dissector_add("udp", dissect_teredo_heur, "Teredo over UDP", "teredo_udp", proto_teredo, HEURISTIC_DISABLE);
}

/*
 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 8
 * tab-width: 8
 * indent-tabs-mode: t
 * End:
 *
 * vi: set shiftwidth=8 tabstop=8 noexpandtab:
 * :indentSize=8:tabSize=8:noTabs=false:
 */