path: root/epan/dissectors/file-file.c

/* file-file.c
 *
 * Top-most file dissector. Decides dissector based on Filetap Encapsulation Type.
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 2000 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#include "config.h"

#ifdef _MSC_VER
#include <windows.h>
#endif

#include <epan/packet.h>
#include <epan/epan.h>
#include <epan/exceptions.h>
#include <epan/show_exception.h>
#include <epan/timestamp.h>
#include <epan/prefs.h>
#include <epan/to_str.h>
#include <epan/tap.h>
#include <epan/expert.h>
#include <epan/proto_data.h>
#include <epan/color_filters.h>
#include <wiretap/wtap.h>
#include <wsutil/str_util.h>

#include "file-file.h"

void proto_register_file(void);

static int proto_file = -1;
static int hf_file_record_number = -1;
static int hf_file_record_len = -1;
static int hf_file_ftap_encap = -1;
static int hf_file_marked = -1;
static int hf_file_ignored = -1;
static int hf_file_protocols = -1;
static int hf_file_num_p_prot_data = -1;
static int hf_file_proto_name_and_key = -1;
static int hf_file_color_filter_name = -1;
static int hf_file_color_filter_text = -1;

static gint ett_file = -1;

static int file_tap = -1;

dissector_table_t file_encap_dissector_table;

/*
 * Routine used to register record end routine.  The routine should only
 * be registered when the dissector is used in the record, not in the
 * proto_register_XXX function.
 */
void
register_file_record_end_routine(packet_info *pinfo, void (*func)(void))
{
	pinfo->frame_end_routines = g_slist_append(pinfo->frame_end_routines, (gpointer)func);
}

typedef void (*void_func_t)(void);

static void
call_file_record_end_routine(gpointer routine, gpointer dummy _U_)
{
	void_func_t func = (void_func_t)routine;
	(*func)();
}

/* XXX - "packet comment" is passed into dissector as data, but currently doesn't have a use */
static int
dissect_file_record(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void* data)
{
	proto_item  *volatile ti = NULL;
	proto_tree  *volatile fh_tree = NULL;
	proto_tree  *volatile tree;
	proto_item  *item;
	const gchar *cap_plurality, *frame_plurality;
	const color_filter_t *color_filter;
	file_data_t *file_data = (file_data_t*)data;

	tree=parent_tree;

	pinfo->current_proto = "File";

	/* if FILE is not referenced from any filters we don't need to worry about
	   generating any tree items.  */
	if(!proto_field_is_referenced(tree, proto_file)) {
		tree=NULL;
	} else {
		guint	     cap_len, frame_len;

		/* Put in frame header information. */
		cap_len = tvb_captured_length(tvb);
		frame_len = tvb_reported_length(tvb);

		cap_plurality = plurality(cap_len, "", "s");
		frame_plurality = plurality(frame_len, "", "s");

		ti = proto_tree_add_protocol_format(tree, proto_file, tvb, 0, -1,
		    "File record %u: %u byte%s",
		    pinfo->num, frame_len, frame_plurality);
		proto_item_append_text(ti, ", %u byte%s",
		    cap_len, cap_plurality);

		fh_tree = proto_item_add_subtree(ti, ett_file);

		if (pinfo->rec->rec_type == REC_TYPE_PACKET)
			proto_tree_add_int(fh_tree, hf_file_ftap_encap, tvb, 0, 0, pinfo->rec->rec_header.packet_header.pkt_encap);

		proto_tree_add_uint(fh_tree, hf_file_record_number, tvb, 0, 0, pinfo->num);

		proto_tree_add_uint_format(fh_tree, hf_file_record_len, tvb,
					   0, 0, frame_len, "Record Length: %u byte%s (%u bits)",
					   frame_len, frame_plurality, frame_len * 8);

		ti = proto_tree_add_boolean(fh_tree, hf_file_marked, tvb, 0, 0,pinfo->fd->marked);
		proto_item_set_generated(ti);

		ti = proto_tree_add_boolean(fh_tree, hf_file_ignored, tvb, 0, 0,pinfo->fd->ignored);
		proto_item_set_generated(ti);

		if(pinfo->fd->pfd != 0){
			proto_item *ppd_item;
			guint num_entries = g_slist_length(pinfo->fd->pfd);
			guint i;
			ppd_item = proto_tree_add_uint(fh_tree, hf_file_num_p_prot_data, tvb, 0, 0, num_entries);
			proto_item_set_generated(ppd_item);
			for(i=0; i<num_entries; i++){
				gchar* str = p_get_proto_name_and_key(wmem_file_scope(), pinfo, i);
				proto_tree_add_string_format(fh_tree, hf_file_proto_name_and_key, tvb, 0, 0, str, "%s", str);
			}
		}

#if 0
		if (show_file_off) {
			proto_tree_add_int64_format_value(fh_tree, hf_frame_file_off, tvb,
						    0, 0, pinfo->fd->file_off,
						    "%" PRId64 " (0x%" PRIx64 ")",
						    pinfo->fd->file_off, pinfo->fd->file_off);
		}
#endif
	}

	if (pinfo->fd->ignored) {
		/* Ignored package, stop handling here */
		col_set_str(pinfo->cinfo, COL_INFO, "<Ignored>");
		proto_tree_add_boolean_format(tree, hf_file_ignored, tvb, 0, -1, TRUE, "This record is marked as ignored");
		return tvb_captured_length(tvb);
	}

	/* Portable Exception Handling to trap Wireshark specific exceptions like BoundsError exceptions */
	TRY {
#ifdef _MSC_VER
		/* Win32: Visual-C Structured Exception Handling (SEH) to trap hardware exceptions
		   like memory access violations.
		   (a running debugger will be called before the except part below) */
		/* Note: A Windows "exceptional exception" may leave the kazlib's (Portable Exception Handling)
		   stack in an inconsistent state thus causing a crash at some point in the
		   handling of the exception.
		   See: https://www.wireshark.org/lists/wireshark-dev/200704/msg00243.html
		*/
		__try {
#endif
			if (pinfo->rec->rec_type != REC_TYPE_PACKET ||
			    !dissector_try_uint(file_encap_dissector_table, pinfo->rec->rec_header.packet_header.pkt_encap,
						tvb, pinfo, parent_tree)) {

				col_set_str(pinfo->cinfo, COL_PROTOCOL, "UNKNOWN");
				col_add_fstr(pinfo->cinfo, COL_INFO, "FTAP_ENCAP = %d",
					     pinfo->rec->rec_header.packet_header.pkt_encap);
				call_data_dissector(tvb, pinfo, parent_tree);
			}
#ifdef _MSC_VER
		} __except(EXCEPTION_EXECUTE_HANDLER /* handle all exceptions */) {
			switch(GetExceptionCode()) {
			case(STATUS_ACCESS_VIOLATION):
				show_exception(tvb, pinfo, parent_tree, DissectorError,
					       "STATUS_ACCESS_VIOLATION: dissector accessed an invalid memory address");
				break;
			case(STATUS_INTEGER_DIVIDE_BY_ZERO):
				show_exception(tvb, pinfo, parent_tree, DissectorError,
					       "STATUS_INTEGER_DIVIDE_BY_ZERO: dissector tried an integer division by zero");
				break;
			case(STATUS_STACK_OVERFLOW):
				show_exception(tvb, pinfo, parent_tree, DissectorError,
					       "STATUS_STACK_OVERFLOW: dissector overflowed the stack (e.g. endless loop)");
				/* XXX - this will have probably corrupted the stack,
				   which makes problems later in the exception code */
				break;
				/* XXX - add other hardware exception codes as required */
			default:
				show_exception(tvb, pinfo, parent_tree, DissectorError,
					       ws_strdup_printf("dissector caused an unknown exception: 0x%x", GetExceptionCode()));
			}
		}
#endif
	}
	CATCH_BOUNDS_AND_DISSECTOR_ERRORS {
		show_exception(tvb, pinfo, parent_tree, EXCEPT_CODE, GET_MESSAGE);
	}
	ENDTRY;

	if(proto_field_is_referenced(tree, hf_file_protocols)) {
		wmem_strbuf_t *val = wmem_strbuf_new(pinfo->pool, "");
		wmem_list_frame_t *frame;
		/* skip the first entry, it's always the "frame" protocol */
		frame = wmem_list_frame_next(wmem_list_head(pinfo->layers));
		if (frame) {
			wmem_strbuf_append(val, proto_get_protocol_filter_name(GPOINTER_TO_UINT(wmem_list_frame_data(frame))));
			frame = wmem_list_frame_next(frame);
		}
		while (frame) {
			wmem_strbuf_append_c(val, ':');
			wmem_strbuf_append(val, proto_get_protocol_filter_name(GPOINTER_TO_UINT(wmem_list_frame_data(frame))));
			frame = wmem_list_frame_next(frame);
		}
		ti = proto_tree_add_string(fh_tree, hf_file_protocols, tvb, 0, 0, wmem_strbuf_get_str(val));
		proto_item_set_generated(ti);
	}

	/*  Call postdissectors if we have any (while trying to avoid another
	 *  TRY/CATCH)
	 */
	if (have_postdissector()) {
		TRY {
#ifdef _MSC_VER
			/* Win32: Visual-C Structured Exception Handling (SEH)
			   to trap hardware exceptions like memory access violations */
			/* (a running debugger will be called before the except part below) */
			/* Note: A Windows "exceptional exception" may leave the kazlib's (Portable Exception Handling)
			   stack in an inconsistent state thus causing a crash at some point in the
			   handling of the exception.
			   See: https://www.wireshark.org/lists/wireshark-dev/200704/msg00243.html
			*/
			__try {
#endif
				call_all_postdissectors(tvb, pinfo, parent_tree);
#ifdef _MSC_VER
			} __except(EXCEPTION_EXECUTE_HANDLER /* handle all exceptions */) {
				switch(GetExceptionCode()) {
				case(STATUS_ACCESS_VIOLATION):
					show_exception(tvb, pinfo, parent_tree, DissectorError,
						       "STATUS_ACCESS_VIOLATION: dissector accessed an invalid memory address");
					break;
				case(STATUS_INTEGER_DIVIDE_BY_ZERO):
					show_exception(tvb, pinfo, parent_tree, DissectorError,
						       "STATUS_INTEGER_DIVIDE_BY_ZERO: dissector tried an integer division by zero");
					break;
				case(STATUS_STACK_OVERFLOW):
					show_exception(tvb, pinfo, parent_tree, DissectorError,
						       "STATUS_STACK_OVERFLOW: dissector overflowed the stack (e.g. endless loop)");
					/* XXX - this will have probably corrupted the stack,
					   which makes problems later in the exception code */
					break;
					/* XXX - add other hardware exception codes as required */
				default:
					show_exception(tvb, pinfo, parent_tree, DissectorError,
						       ws_strdup_printf("dissector caused an unknown exception: 0x%x", GetExceptionCode()));
				}
			}
#endif
		}
		CATCH_BOUNDS_AND_DISSECTOR_ERRORS {
			show_exception(tvb, pinfo, parent_tree, EXCEPT_CODE, GET_MESSAGE);
		}
		ENDTRY;
	}

	/* Attempt to (re-)calculate color filters (if any). */
	if (pinfo->fd->need_colorize) {
		color_filter = color_filters_colorize_packet(file_data->color_edt);
		pinfo->fd->color_filter = color_filter;
		pinfo->fd->need_colorize = 0;
	} else {
		color_filter = pinfo->fd->color_filter;
	}
	if (color_filter) {
		pinfo->fd->color_filter = color_filter;
		item = proto_tree_add_string(fh_tree, hf_file_color_filter_name, tvb,
					     0, 0, color_filter->filter_name);
		proto_item_set_generated(item);
		item = proto_tree_add_string(fh_tree, hf_file_color_filter_text, tvb,
					     0, 0, color_filter->filter_text);
		proto_item_set_generated(item);
	}

	tap_queue_packet(file_tap, pinfo, NULL);


	if (pinfo->frame_end_routines) {
		g_slist_foreach(pinfo->frame_end_routines, &call_file_record_end_routine, NULL);
		g_slist_free(pinfo->frame_end_routines);
		pinfo->frame_end_routines = NULL;
	}

	return tvb_captured_length(tvb);
}

void
proto_register_file(void)
{
	static hf_register_info hf[] = {
		{ &hf_file_record_number,
		  { "Record Number", "file.record_number",
		    FT_UINT32, BASE_DEC, NULL, 0x0,
		    NULL, HFILL }},

		{ &hf_file_record_len,
		  { "Record length", "file.record_len",
		    FT_UINT32, BASE_DEC, NULL, 0x0,
		    NULL, HFILL }},
#if 0
		{ &hf_frame_file_off,
		  { "File Offset", "file.offset",
		    FT_INT64, BASE_DEC, NULL, 0x0,
		    NULL, HFILL }},
#endif
		{ &hf_file_marked,
		  { "File record is marked", "file.marked",
		    FT_BOOLEAN, BASE_NONE, NULL, 0x0,
		    "File record is marked in the GUI", HFILL }},

		{ &hf_file_ignored,
		  { "File record is ignored", "file.ignored",
		    FT_BOOLEAN, BASE_NONE, NULL, 0x0,
		    "File record is ignored by the dissectors", HFILL }},

		{ &hf_file_protocols,
		  { "File record types in frame", "file.record_types",
		    FT_STRING, BASE_NONE, NULL, 0x0,
		    "File record types carried by this frame", HFILL }},

		{ &hf_file_color_filter_name,
		  { "Coloring Rule Name", "file.coloring_rule.name",
		    FT_STRING, BASE_NONE, NULL, 0x0,
		    "The file record matched the coloring rule with this name", HFILL }},

		{ &hf_file_color_filter_text,
		  { "Coloring Rule String", "file.coloring_rule.string",
		    FT_STRING, BASE_NONE, NULL, 0x0,
		    "The file record matched this coloring rule string", HFILL }},

		{ &hf_file_num_p_prot_data,
		  { "Number of per-record-data", "file.p_record_data",
		    FT_UINT32, BASE_DEC, NULL, 0x0,
		    NULL, HFILL }},

		{ &hf_file_proto_name_and_key,
		  { "Protocol Name and Key", "file.proto_name_and_key",
		    FT_STRING, BASE_NONE, NULL, 0x0,
		    NULL, HFILL }},

		{ &hf_file_ftap_encap,
		  { "Encapsulation type", "file.encap_type",
		    FT_INT16, BASE_DEC, NULL, 0x0,
		    NULL, HFILL }},
	};

 	static gint *ett[] = {
		&ett_file
	};

#if 0
	module_t *file_module;
#endif

	proto_file = proto_register_protocol("File", "File", "file");
	proto_register_field_array(proto_file, hf, array_length(hf));
	proto_register_subtree_array(ett, array_length(ett));
	register_dissector("file",dissect_file_record,proto_file);

	file_encap_dissector_table = register_dissector_table("ftap_encap",
	    "Filetap encapsulation type", proto_file, FT_UINT32, BASE_DEC);

	/* You can't disable dissection of "Frame", as that would be
	   tantamount to not doing any dissection whatsoever. */
	proto_set_cant_toggle(proto_file);

	/* Our preferences */
#if 0
	frame_module = prefs_register_protocol(proto_frame, NULL);
	prefs_register_bool_preference(frame_module, "show_file_off",
	    "Show File Offset", "Show offset of frame in capture file", &show_file_off);
#endif

	file_tap=register_tap("file");
}

/*
 * 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:
 */