/* packet-json.c
 * Routines for JSON dissection
 * References:
 *     RFC 4627: http://tools.ietf.org/html/rfc4627
 *     Website:  http://json.org/
 *
 * Copyright 2010, Jakub Zawadzki <darkjames-ws@darkjames.pl>
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#define NEW_PROTO_TREE_API

#include "config.h"

#include <glib.h>

#include <epan/wmem/wmem.h>
#include <epan/packet.h>
#include <epan/tvbparse.h>

#include <wsutil/str_util.h>
#include <wsutil/unicode-utils.h>

void proto_register_json(void);
void proto_reg_handoff_json(void);

static dissector_handle_t json_handle;

static gint ett_json = -1;
static gint ett_json_array = -1;
static gint ett_json_object = -1;
static gint ett_json_member = -1;

static header_field_info *hfi_json = NULL;

#define JSON_HFI_INIT HFI_INIT(proto_json)

static header_field_info hfi_json_array JSON_HFI_INIT =
	{ "Array", "json.array", FT_NONE, BASE_NONE, NULL, 0x00, "JSON array", HFILL };

static header_field_info hfi_json_object JSON_HFI_INIT =
	{ "Object", "json.object", FT_NONE, BASE_NONE, NULL, 0x00, "JSON object", HFILL };

static header_field_info hfi_json_member JSON_HFI_INIT =
	{ "Member", "json.member", FT_NONE, BASE_NONE, NULL, 0x00, "JSON object member", HFILL };

#if 0
/* XXX */
static header_field_info hfi_json_member_key JSON_HFI_INIT =
	{ "Key", "json.member.key", FT_NONE, BASE_NONE, NULL, 0x00, NULL, HFILL };
#endif

static header_field_info hfi_json_value_string JSON_HFI_INIT = /* FT_STRINGZ? */
	{ "String value", "json.value.string", FT_STRING, STR_UNICODE, NULL, 0x00, "JSON string value", HFILL };

static header_field_info hfi_json_value_number JSON_HFI_INIT = /* FT_DOUBLE/ FT_INT64? */
	{ "Number value", "json.value.number", FT_STRING, BASE_NONE, NULL, 0x00, "JSON number value", HFILL };

static header_field_info hfi_json_value_false JSON_HFI_INIT =
	{ "False value", "json.value.false", FT_NONE, BASE_NONE, NULL, 0x00, "JSON false value", HFILL };

static header_field_info hfi_json_value_null JSON_HFI_INIT =
	{ "Null value", "json.value.null", FT_NONE, BASE_NONE, NULL, 0x00, "JSON null value", HFILL };

static header_field_info hfi_json_value_true JSON_HFI_INIT =
	{ "True value", "json.value.true", FT_NONE, BASE_NONE, NULL, 0x00, "JSON true value", HFILL };


static tvbparse_wanted_t* want;
static tvbparse_wanted_t* want_ignore;

static dissector_handle_t text_lines_handle;

typedef enum {
	JSON_TOKEN_INVALID = -1,
	JSON_TOKEN_NUMBER = 0,
	JSON_TOKEN_STRING,
	JSON_TOKEN_FALSE,
	JSON_TOKEN_NULL,
	JSON_TOKEN_TRUE,

	/* not really tokens ... */
	JSON_OBJECT,
	JSON_ARRAY

} json_token_type_t;

typedef struct {
	wmem_stack_t *stack;

} json_parser_data_t;

static int
dissect_json(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data)
{
	proto_tree *json_tree = NULL;
	proto_item *ti = NULL;

	json_parser_data_t parser_data;
	tvbparse_t *tt;

	const char *data_name;
	int offset;

	data_name = pinfo->match_string;
	if (! (data_name && data_name[0])) {
		/*
		 * No information from "match_string"
		 */
		data_name = (char *)data;
		if (! (data_name && data_name[0])) {
			/*
			 * No information from dissector data
			 */
			data_name = (char *)(pinfo->private_data);
			if (! (data_name && data_name[0])) {
				/*
				 * No information from "private_data"
				 */
				data_name = NULL;
			}
		}
	}

	if (tree) {
		ti = proto_tree_add_item(tree, hfi_json, tvb, 0, -1, ENC_NA);
		json_tree = proto_item_add_subtree(ti, ett_json);

		if (data_name)
			proto_item_append_text(ti, ": %s", data_name);
	}

	offset = 0;

	parser_data.stack = wmem_stack_new(wmem_packet_scope());
	wmem_stack_push(parser_data.stack, json_tree);

	tt = tvbparse_init(tvb, offset, -1, &parser_data, want_ignore);

	/* XXX, only one json in packet? */
	while ((tvbparse_get(tt, want)))
		;

	offset = tvbparse_curr_offset(tt);

	proto_item_set_len(ti, offset);

	/* if we have some unparsed data, pass to data-text-lines dissector (?) */
	if (tvb_length_remaining(tvb, offset) > 0) {
		int datalen, reported_datalen;
		tvbuff_t *next_tvb;

		datalen = tvb_length_remaining(tvb, offset);
		reported_datalen = tvb_reported_length_remaining(tvb, offset);

		next_tvb = tvb_new_subset(tvb, offset, datalen, reported_datalen);

		call_dissector(text_lines_handle, next_tvb, pinfo, tree);
	} else if (data_name) {
		col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "(%s)", data_name);
	}

	return tvb_length(tvb);
}

static void before_object(void *tvbparse_data, const void *wanted_data _U_, tvbparse_elem_t *tok) {
	json_parser_data_t *data = (json_parser_data_t *) tvbparse_data;

	proto_tree *tree = (proto_tree *)wmem_stack_peek(data->stack);
	proto_tree *subtree;
	proto_item *ti;

	ti = proto_tree_add_item(tree, &hfi_json_object, tok->tvb, tok->offset, tok->len, ENC_NA);

	subtree = proto_item_add_subtree(ti, ett_json_object);
	wmem_stack_push(data->stack, subtree);
}

static void after_object(void *tvbparse_data, const void *wanted_data _U_, tvbparse_elem_t *elem _U_) {
	json_parser_data_t *data = (json_parser_data_t *) tvbparse_data;

	wmem_stack_pop(data->stack);
}

static void before_member(void *tvbparse_data, const void *wanted_data _U_, tvbparse_elem_t *tok) {
	json_parser_data_t *data = (json_parser_data_t *) tvbparse_data;

	proto_tree *tree = (proto_tree *)wmem_stack_peek(data->stack);
	proto_tree *subtree;
	proto_item *ti;

	ti = proto_tree_add_item(tree, &hfi_json_member, tok->tvb, tok->offset, tok->len, ENC_NA);

	subtree = proto_item_add_subtree(ti, ett_json_member);
	wmem_stack_push(data->stack, subtree);
}

static void after_member(void *tvbparse_data, const void *wanted_data _U_, tvbparse_elem_t *tok) {
	json_parser_data_t *data = (json_parser_data_t *) tvbparse_data;

	proto_tree *tree = (proto_tree *)wmem_stack_pop(data->stack);

	if (tree) {
		tvbparse_elem_t *key_tok = tok->sub;

		if (key_tok && key_tok->id == JSON_TOKEN_STRING) {
			char *key = tvb_get_string(wmem_packet_scope(), key_tok->tvb, key_tok->offset, key_tok->len);

			proto_item_append_text(tree, " Key: %s", key);
		}
		/* XXX, &hfi_json_member_key */
	}
}

static void before_array(void *tvbparse_data, const void *wanted_data _U_, tvbparse_elem_t *tok) {
	json_parser_data_t *data = (json_parser_data_t *) tvbparse_data;

	proto_tree *tree = (proto_tree *)wmem_stack_peek(data->stack);
	proto_tree *subtree;
	proto_item *ti;

	ti = proto_tree_add_item(tree, &hfi_json_array, tok->tvb, tok->offset, tok->len, ENC_NA);

	subtree = proto_item_add_subtree(ti, ett_json_array);
	wmem_stack_push(data->stack, subtree);
}

static void after_array(void *tvbparse_data, const void *wanted_data _U_, tvbparse_elem_t *elem _U_) {
	json_parser_data_t *data = (json_parser_data_t *) tvbparse_data;

	wmem_stack_pop(data->stack);
}

static int
json_tvb_memcpy_utf8(char *buf, tvbuff_t *tvb, int offset, int offset_max)
{
	int len = ws_utf8_char_len((guint8) *buf);

	/* XXX, before moving to core API check if it's off-by-one safe.
	 * For JSON analyzer it's not a problem
	 * (string always terminated by ", which is not valid UTF-8 continuation character) */
	if (len == -1 || ((guint) (offset + len)) >= (guint) offset_max) {
		*buf = '?';
		return 1;
	}

	/* assume it's valid UTF-8 */
	tvb_memcpy(tvb, buf + 1, offset + 1, len - 1);

	if (!g_utf8_validate(buf, len, NULL)) {
		*buf = '?';
		return 1;
	}

	return len;
}

static char *json_string_unescape(tvbparse_elem_t *tok)
{
	char *str = (char *)wmem_alloc(wmem_packet_scope(), tok->len - 1);
	int i, j;

	j = 0;
	for (i = 1; i < tok->len - 1; i++) {
		guint8 ch = tvb_get_guint8(tok->tvb, tok->offset + i);
		int bin;

		if (ch == '\\') {
			i++;

			ch = tvb_get_guint8(tok->tvb, tok->offset + i);
			switch (ch) {
				case '\"':
				case '\\':
				case '/':
					str[j++] = ch;
					break;

				case 'b':
					str[j++] = '\b';
					break;
				case 'f':
					str[j++] = '\f';
					break;
				case 'n':
					str[j++] = '\n';
					break;
				case 'r':
					str[j++] = '\r';
					break;
				case 't':
					str[j++] = '\t';
					break;

				case 'u':
				{
					guint32 unicode_hex = 0;
					gboolean valid = TRUE;
					int k;

					for (k = 0; k < 4; k++) {
						i++;
						unicode_hex <<= 4;

						ch = tvb_get_guint8(tok->tvb, tok->offset + i);
						bin = ws_xton(ch);
						if (bin == -1) {
							valid = FALSE;
							break;
						}
						unicode_hex |= bin;
					}

					if ((IS_LEAD_SURROGATE(unicode_hex))) {
						ch = tvb_get_guint8(tok->tvb, tok->offset + i + 1);

						if (ch == '\\') {
							i++;
							ch = tvb_get_guint8(tok->tvb, tok->offset + i + 1);
							if (ch == 'u') {
								guint16 lead_surrogate = unicode_hex;
								guint16 trail_surrogate = 0;
								i++;

								for (k = 0; k < 4; k++) {
									i++;
									trail_surrogate <<= 4;

									ch = tvb_get_guint8(tok->tvb, tok->offset + i);
									bin = ws_xton(ch);
									if (bin == -1) {
										valid = FALSE;
										break;
									}
									trail_surrogate |= bin;
								}

								if ((IS_TRAIL_SURROGATE(trail_surrogate))) {
									unicode_hex = SURROGATE_VALUE(lead_surrogate,trail_surrogate);
								} else {
									valid = FALSE;
								}
							} else {
								valid = FALSE;
							}
						} else {
							valid = FALSE;
						}
					} else if ((IS_TRAIL_SURROGATE(unicode_hex))) {
						i++;
						valid = FALSE;
					}

					if (valid && g_unichar_validate(unicode_hex) && g_unichar_isprint(unicode_hex)) {
						/* \uXXXX => 6 bytes */
						int charlen = g_unichar_to_utf8(unicode_hex, &str[j]);
						j += charlen;
					} else
						str[j++] = '?';
					break;
				}

				default:
					/* not valid by JSON grammar (also tvbparse rules should not allow it) */
					DISSECTOR_ASSERT_NOT_REACHED();
					break;
			}

		} else {
			int utf_len;

			str[j] = ch;
			/* XXX if it's not valid UTF-8 character, add some expert info? (it violates JSON grammar) */
			utf_len = json_tvb_memcpy_utf8(&str[j], tok->tvb, i, tok->len);
			j += utf_len;
			i += (utf_len - 1);
		}

	}
	str[j] = '\0';

	return str;
}

static void after_value(void *tvbparse_data, const void *wanted_data _U_, tvbparse_elem_t *tok) {
	json_parser_data_t *data = (json_parser_data_t *) tvbparse_data;

	proto_tree *tree = (proto_tree *)wmem_stack_peek(data->stack);
	json_token_type_t value_id = JSON_TOKEN_INVALID;

	if (tok->sub)
		value_id = (json_token_type_t)tok->sub->id;

	switch (value_id) {
		case JSON_TOKEN_STRING:
			if (tok->len >= 2)
				proto_tree_add_string(tree, &hfi_json_value_string, tok->tvb, tok->offset, tok->len, json_string_unescape(tok));
			else
				proto_tree_add_item(tree, &hfi_json_value_string, tok->tvb, tok->offset, tok->len, ENC_ASCII|ENC_NA);
			break;

		case JSON_TOKEN_NUMBER:
			/* XXX, convert to number */
			proto_tree_add_item(tree, &hfi_json_value_number, tok->tvb, tok->offset, tok->len, ENC_ASCII|ENC_NA);
			break;

		case JSON_TOKEN_FALSE:
			proto_tree_add_item(tree, &hfi_json_value_false, tok->tvb, tok->offset, tok->len, ENC_NA);
			break;

		case JSON_TOKEN_NULL:
			proto_tree_add_item(tree, &hfi_json_value_null, tok->tvb, tok->offset, tok->len, ENC_NA);
			break;

		case JSON_TOKEN_TRUE:
			proto_tree_add_item(tree, &hfi_json_value_true, tok->tvb, tok->offset, tok->len, ENC_NA);
			break;

		case JSON_OBJECT:
		case JSON_ARRAY:
			/* already added */
			break;

		default:
			proto_tree_add_format_text(tree, tok->tvb, tok->offset, tok->len);
			break;
	}
}

static void init_json_parser(void) {
	static tvbparse_wanted_t _want_object;
	static tvbparse_wanted_t _want_array;

	tvbparse_wanted_t *want_object, *want_array;
	tvbparse_wanted_t *want_member;
	tvbparse_wanted_t *want_string;
	tvbparse_wanted_t *want_number, *want_int;
	tvbparse_wanted_t *want_value;
	tvbparse_wanted_t *want_value_separator;

#define tvbparse_optional(id, private_data, before_cb, after_cb, wanted) \
	tvbparse_some(id, 0, 1, private_data, before_cb, after_cb, wanted)

	tvbparse_wanted_t *want_quot = tvbparse_char(-1,"\"",NULL,NULL,NULL);

	want_string = tvbparse_set_seq(JSON_TOKEN_STRING, NULL, NULL, NULL,
			want_quot,
			tvbparse_some(-1, 0, G_MAXINT, NULL, NULL, NULL,
				tvbparse_set_oneof(-1, NULL, NULL, NULL,
					tvbparse_not_chars(-1, 0, 0, "\"" "\\", NULL, NULL, NULL), /* XXX, without invalid unicode characters */
					tvbparse_set_seq(-1, NULL, NULL, NULL,
						tvbparse_char(-1, "\\", NULL, NULL, NULL),
						tvbparse_set_oneof(-1, NULL, NULL, NULL,
							tvbparse_chars(-1, 0, 1, "\"" "\\" "/bfnrt", NULL, NULL, NULL),
							tvbparse_set_seq(-1, NULL, NULL, NULL,
								tvbparse_char(-1, "u", NULL, NULL, NULL),
								tvbparse_chars(-1, 4, 4, "0123456789abcdefABCDEF", NULL, NULL, NULL),
								NULL),
							NULL),
						NULL),
					NULL)
				),
			want_quot,
			NULL);

	want_value_separator = tvbparse_char(-1, ",", NULL, NULL, NULL);

	/* int = zero / ( digit1-9 *DIGIT ) */
	want_int = tvbparse_set_oneof(-1, NULL, NULL, NULL,
			tvbparse_char(-1, "0", NULL, NULL, NULL),
			tvbparse_set_seq(-1, NULL, NULL, NULL,
				tvbparse_chars(-1, 1, 1, "123456789", NULL, NULL, NULL),
				tvbparse_optional(-1, NULL, NULL, NULL, /* tvbparse_chars() don't respect 0 as min_len ;/ */
					tvbparse_chars(-1, 0, 0, "0123456789", NULL, NULL, NULL)),
				NULL),
			NULL);

	/* number = [ minus ] int [ frac ] [ exp ] */
	want_number = tvbparse_set_seq(JSON_TOKEN_NUMBER, NULL, NULL, NULL,
			tvbparse_optional(-1, NULL, NULL, NULL, /* tvbparse_chars() don't respect 0 as min_len ;/ */
				tvbparse_chars(-1, 0, 1, "-", NULL, NULL, NULL)),
			want_int,
			/* frac = decimal-point 1*DIGIT */
			tvbparse_optional(-1, NULL, NULL, NULL,
				tvbparse_set_seq(-1, NULL, NULL, NULL,
					tvbparse_char(-1, ".", NULL, NULL, NULL),
					tvbparse_chars(-1, 1, 0, "0123456789", NULL, NULL, NULL),
					NULL)),
			/* exp = e [ minus / plus ] 1*DIGIT */
			tvbparse_optional(-1, NULL, NULL, NULL,
				tvbparse_set_seq(-1, NULL, NULL, NULL,
					tvbparse_char(-1, "eE", NULL, NULL, NULL),
					tvbparse_optional(-1, NULL, NULL, NULL, /* tvbparse_chars() don't respect 0 as min_len ;/ */
						tvbparse_chars(-1, 0, 1, "-+", NULL, NULL, NULL)),
					tvbparse_chars(-1, 1, 0, "0123456789", NULL, NULL, NULL),
					NULL)),
			NULL);

	/* value = false / null / true / object / array / number / string */
	want_value = tvbparse_set_oneof(-1, NULL, NULL, after_value,
			tvbparse_string(JSON_TOKEN_FALSE, "false", NULL, NULL, NULL),
			tvbparse_string(JSON_TOKEN_NULL, "null", NULL, NULL, NULL),
			tvbparse_string(JSON_TOKEN_TRUE, "true", NULL, NULL, NULL),
			&_want_object,
			&_want_array,
			want_number,
			want_string,
			NULL);

	/* array = begin-array [ value *( value-separator value ) ] end-array */
	want_array = tvbparse_set_seq(JSON_ARRAY, NULL, before_array, after_array,
			tvbparse_char(-1, "[", NULL, NULL, NULL),
			tvbparse_optional(-1, NULL, NULL, NULL,
				tvbparse_set_seq(-1, NULL, NULL, NULL,
					want_value,
					tvbparse_some(-1, 0, G_MAXINT, NULL, NULL, NULL,
						tvbparse_set_seq(-1, NULL, NULL, NULL,
							want_value_separator,
							want_value,
							NULL)),
					NULL)
				),
			tvbparse_char(-1, "]", NULL, NULL, NULL),
			NULL);
	_want_array = *want_array;

	/* member = string name-separator value */
	want_member = tvbparse_set_seq(-1, NULL, before_member, after_member,
			want_string,
			tvbparse_char(-1, ":", NULL, NULL, NULL),
			want_value,
			NULL);

	/* object = begin-object [ member *( value-separator member ) ] end-object */
	want_object = tvbparse_set_seq(JSON_OBJECT, NULL, before_object, after_object,
			tvbparse_char(-1, "{", NULL, NULL, NULL),
			tvbparse_optional(-1, NULL, NULL, NULL,
				tvbparse_set_seq(-1, NULL, NULL, NULL,
					want_member,
					tvbparse_some(-1, 0, G_MAXINT, NULL, NULL, NULL,
						tvbparse_set_seq(-1, NULL, NULL, NULL,
							want_value_separator,
							want_member,
							NULL)),
					NULL)
				),
			tvbparse_char(-1, "}", NULL, NULL, NULL),
			NULL);
	_want_object = *want_object;

	want_ignore = tvbparse_chars(-1, 1, 0, " \t\r\n", NULL, NULL, NULL);

	/* JSON-text = object / array */
	want = tvbparse_set_oneof(-1, NULL, NULL, NULL,
		want_object,
		want_array,
		/* tvbparse_not_chars(-1, 1, 0, " \t\r\n", NULL, NULL, NULL), */
		NULL);

	/* XXX, heur? */
}

void
proto_register_json(void)
{
	static gint *ett[] = {
		&ett_json,
		&ett_json_array,
		&ett_json_object,
		&ett_json_member
	};

#ifndef HAVE_HFI_SECTION_INIT
	static header_field_info *hfi[] = {
		&hfi_json_array,
		&hfi_json_object,
		&hfi_json_member,
		/* &hfi_json_member_key, */
		&hfi_json_value_string,
		&hfi_json_value_number,
		&hfi_json_value_false,
		&hfi_json_value_null,
		&hfi_json_value_true,
	};
#endif

	int proto_json;

	proto_json = proto_register_protocol("JavaScript Object Notation", "JSON", "json");
	hfi_json = proto_registrar_get_nth(proto_json);

	proto_register_fields(proto_json, hfi, array_length(hfi));
	proto_register_subtree_array(ett, array_length(ett));

	json_handle = new_register_dissector("json", dissect_json, proto_json);

	init_json_parser();
}

void
proto_reg_handoff_json(void)
{
	dissector_add_string("media_type", "application/json", json_handle); /* RFC 4627 */
	dissector_add_string("media_type", "application/json-rpc", json_handle); /* JSON-RPC over HTTP */
	dissector_add_string("media_type", "application/jsonrequest", json_handle); /* JSON-RPC over HTTP */

	text_lines_handle = find_dissector("data-text-lines");
}

