wireshark/epan/dfilter/syntax-tree.c

/*
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 2001 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#include "config.h"

#define WS_LOG_DOMAIN LOG_DOMAIN_DFILTER

#include "syntax-tree.h"
#include <wsutil/wmem/wmem.h>
#include <wsutil/str_util.h>
#include <wsutil/glib-compat.h>
#include "sttype-op.h"
#include "sttype-function.h"
#include "dfilter-int.h"

/* Keep track of sttype_t's via their sttype_id_t number */
static sttype_t* type_list[STTYPE_NUM_TYPES];


#define STNODE_MAGIC	0xe9b00b9e


void
sttype_init(void)
{
	sttype_register_field();
	sttype_register_function();
	sttype_register_pointer();
	sttype_register_set();
	sttype_register_slice();
	sttype_register_string();
	sttype_register_opers();
}

void
sttype_cleanup(void)
{
	/* nothing to do */
}


void
sttype_register(sttype_t *type)
{
	sttype_id_t	type_id;

	type_id = type->id;

	/* Check input */
	ws_assert(type_id < STTYPE_NUM_TYPES);

	/* Don't re-register. */
	ws_assert(type_list[type_id] == NULL);

	type_list[type_id] = type;
}

static sttype_t*
sttype_lookup(sttype_id_t type_id)
{
	sttype_t	*result;

	/* Check input */
	ws_assert(type_id < STTYPE_NUM_TYPES);

	result = type_list[type_id];

	/* Check output. */
	ws_assert(result != NULL);

	return result;
}

void
stnode_clear(stnode_t *node)
{
	ws_assert_magic(node, STNODE_MAGIC);
	if (node->type) {
		if (node->type->func_free && node->data) {
			node->type->func_free(node->data);
		}
	}
	else {
		ws_assert(!node->data);
	}

	node->type = NULL;
	node->data = NULL;
	g_free(node->repr_display);
	node->repr_display = NULL;
	g_free(node->repr_debug);
	node->repr_debug = NULL;
	g_free(node->repr_token);
	node->repr_token = NULL;
	node->location.col_start = -1;
	node->location.col_len = 0;
}

void
stnode_init(stnode_t *node, sttype_id_t type_id, gpointer data, char *token, const stloc_t *loc)
{
	sttype_t	*type;

	ws_assert_magic(node, STNODE_MAGIC);
	ws_assert(!node->type);
	ws_assert(!node->data);
	node->repr_display = NULL;
	node->repr_debug = NULL;
	node->repr_token = token;
	if (loc) {
		node->location = *loc;
	}
	else {
		node->location.col_start = -1;
		node->location.col_len = 0;
	}

	if (type_id == STTYPE_UNINITIALIZED) {
		node->type = NULL;
		node->data = NULL;
	}
	else {
		/* Creating an initialized node with a NULL pointer is
		 * allowed and needs to be safe. The parser relies on that. */
		type = sttype_lookup(type_id);
		ws_assert(type);
		node->type = type;
		if (type->func_new) {
			node->data = type->func_new(data);
		}
		else {
			node->data = data;
		}
	}
}

void
stnode_replace(stnode_t *node, sttype_id_t type_id, gpointer data)
{
	char *token = g_strdup(node->repr_token);
	stloc_t loc = node->location;
	stnode_clear(node);
	stnode_init(node, type_id, data, token, &loc);
}

stnode_t*
stnode_new(sttype_id_t type_id, gpointer data, char *token, const stloc_t *loc)
{
	stnode_t	*node;

	node = g_new0(stnode_t, 1);
	node->magic = STNODE_MAGIC;

	stnode_init(node, type_id, data, token, loc);

	return node;
}

stnode_t*
stnode_dup(const stnode_t *node)
{
	stnode_t *new;

	ws_assert_magic(node, STNODE_MAGIC);
	new = g_new(stnode_t, 1);
	new->magic = STNODE_MAGIC;
	new->repr_display = NULL;
	new->repr_debug = NULL;
	new->repr_token = g_strdup(node->repr_token);
	new->location = node->location;

	new->type = node->type;
	if (node->type == NULL)
		new->data = NULL;
	else if (node->type->func_dup)
		new->data = node->type->func_dup(node->data);
	else
		new->data = node->data;

	return new;
}

void
stnode_free(stnode_t *node)
{
	ws_assert_magic(node, STNODE_MAGIC);
	stnode_clear(node);
	g_free(node);
}

const char*
stnode_type_name(stnode_t *node)
{
	ws_assert_magic(node, STNODE_MAGIC);
	if (node->type)
		return node->type->name;
	else
		return "UNINITIALIZED";
}

sttype_id_t
stnode_type_id(stnode_t *node)
{
	ws_assert_magic(node, STNODE_MAGIC);
	if (node->type)
		return node->type->id;
	else
		return STTYPE_UNINITIALIZED;
}

gpointer
stnode_data(stnode_t *node)
{
	ws_assert_magic(node, STNODE_MAGIC);
	return node->data;
}

GString *
stnode_string(stnode_t *node)
{
	ws_assert(stnode_type_id(node) == STTYPE_STRING);
	return stnode_data(node);
}

gpointer
stnode_steal_data(stnode_t *node)
{
	ws_assert_magic(node, STNODE_MAGIC);
	gpointer data = node->data;
	ws_assert(data);
	node->data = NULL;
	return data;
}

const char *
stnode_token(stnode_t *node)
{
	return node->repr_token;
}

stloc_t *
stnode_location(stnode_t *node)
{
	return &node->location;
}

#define IS_OPERATOR(node) \
	(stnode_type_id(node) == STTYPE_TEST || \
		stnode_type_id(node) == STTYPE_ARITHMETIC)

static char *
_node_tostr(stnode_t *node, gboolean pretty)
{
	char *s, *repr;

	if (node->type->func_tostr == NULL)
		s = g_strdup("FIXME");
	else
		s = node->type->func_tostr(node->data, pretty);

	if (pretty)
		return s;

	if (IS_OPERATOR(node)) {
		repr = s;
	}
	else {
		repr = ws_strdup_printf("%s(%s)", stnode_type_name(node), s);
		g_free(s);
	}

	return repr;
}

const char *
stnode_tostr(stnode_t *node, gboolean pretty)
{
	ws_assert_magic(node, STNODE_MAGIC);

	if (pretty && IS_OPERATOR(node) && node->repr_token != NULL) {
		/* Some operators can have synonyms, like "or" and "||".
		 * Show the user the same representation as he typed. */
		g_free(node->repr_display);
		node->repr_display = g_strdup(node->repr_token);
		return node->repr_display;
	}

	char *str = _node_tostr(node, pretty);

	if (pretty) {
		g_free(node->repr_display);
		node->repr_display = str;
	}
	else {
		g_free(node->repr_debug);
		node->repr_debug = str;
	}

	return str;
}

static char *
sprint_node(stnode_t *node)
{
	wmem_strbuf_t *buf = wmem_strbuf_new(NULL, NULL);

	wmem_strbuf_append_printf(buf, "stnode{ ");
	wmem_strbuf_append_printf(buf, "magic=0x%"PRIx32", ", node->magic);
	wmem_strbuf_append_printf(buf, "type=%s, ", stnode_type_name(node));
	wmem_strbuf_append_printf(buf, "data=<%s>, ", stnode_todebug(node));
	wmem_strbuf_append_printf(buf, "location=%ld:%zu",
			node->location.col_start, node->location.col_len);
	return wmem_strbuf_finalize(buf);
}

void
log_node_full(enum ws_log_level level,
			const char *file, int line, const char *func,
			stnode_t *node, const char *msg)
{
	if (!ws_log_msg_is_active(WS_LOG_DOMAIN, level))
		return;

	if (node == NULL) {
		ws_log_write_always_full(WS_LOG_DOMAIN, level,
					file, line, func, "%s is NULL", msg);
		return;
	}

	char *str = sprint_node(node);

	ws_log_write_always_full(WS_LOG_DOMAIN, level, file, line, func,
				"%s = %s", msg, str);

	g_free(str);
}

void
log_test_full(enum ws_log_level level,
			const char *file, int line, const char *func,
			stnode_t *node, const char *msg)
{
	if (!ws_log_msg_is_active(WS_LOG_DOMAIN, level))
		return;

	if (node == NULL) {
		ws_log_write_always_full(WS_LOG_DOMAIN, level,
					file, line, func, "%s is NULL", msg);
		return;
	}

	stnode_op_t st_op;
	stnode_t *st_lhs = NULL, *st_rhs = NULL;
	char *lhs = NULL, *rhs = NULL;

	sttype_oper_get(node, &st_op, &st_lhs, &st_rhs);

	if (st_lhs)
		lhs = sprint_node(st_lhs);
	if (st_rhs)
		rhs = sprint_node(st_rhs);

	ws_log_write_always_full(WS_LOG_DOMAIN, level, file, line, func,
				"%s: LHS = %s; RHS = %s",
				stnode_todebug(node),
				lhs ? lhs : "NULL",
				rhs ? rhs : "NULL");

	g_free(lhs);
	g_free(rhs);
}

static void
indent(wmem_strbuf_t *buf, int level)
{
	for (int i = 0; i < level * 2; i++) {
		wmem_strbuf_append_c(buf, ' ');
	}
	wmem_strbuf_append_printf(buf, "% 2d ", level);
}

static void
visit_tree(wmem_strbuf_t *buf, stnode_t *node, int level)
{
	stnode_t *left, *right;
	stnode_t *lower, *upper;
	GSList *params;
	GSList *nodelist;

	if (stnode_type_id(node) == STTYPE_TEST ||
			stnode_type_id(node) == STTYPE_ARITHMETIC) {
		wmem_strbuf_append_printf(buf, "%s:\n", stnode_todebug(node));
		sttype_oper_get(node, NULL, &left, &right);
		if (left && right) {
			indent(buf, level + 1);
			visit_tree(buf, left, level + 1);
			wmem_strbuf_append_c(buf, '\n');
			indent(buf, level + 1);
			visit_tree(buf, right, level + 1);
		}
		else if (left) {
			indent(buf, level + 1);
			visit_tree(buf, left, level + 1);
		}
		else if (right) {
			ws_assert_not_reached();
		}
	}
	else if (stnode_type_id(node) == STTYPE_SET) {
		nodelist = stnode_data(node);
		wmem_strbuf_append_printf(buf, "SET(#%u):\n", g_slist_length(nodelist) / 2);
		while (nodelist) {
			indent(buf, level + 1);
			lower = nodelist->data;
			wmem_strbuf_append(buf, stnode_tostr(lower, FALSE));
			/* Set elements are always in pairs; upper may be null. */
			nodelist = g_slist_next(nodelist);
			ws_assert(nodelist);
			upper = nodelist->data;
			if (upper != NULL) {
				wmem_strbuf_append(buf, " .. ");
				wmem_strbuf_append(buf, stnode_tostr(upper, FALSE));
			}
			nodelist = g_slist_next(nodelist);
			if (nodelist != NULL) {
				wmem_strbuf_append_c(buf, '\n');
			}
		}
	}
	else if (stnode_type_id(node) == STTYPE_FUNCTION) {
		wmem_strbuf_append_printf(buf, "%s:\n", stnode_todebug(node));
		params = sttype_function_params(node);
		while (params) {
			indent(buf, level + 1);
			visit_tree(buf, params->data, level + 1);
			if (params->next != NULL) {
				wmem_strbuf_append_c(buf, '\n');
			}
			params = params->next;
		}
	}
	else {
		wmem_strbuf_append(buf, stnode_todebug(node));
	}
}

char *
dump_syntax_tree_str(stnode_t *root)
{
	wmem_strbuf_t *buf = wmem_strbuf_new(NULL, NULL);
	indent(buf, 0);
	visit_tree(buf, root, 0);
	return wmem_strbuf_finalize(buf);
}

void
log_syntax_tree(enum ws_log_level level, stnode_t *root, const char *msg, char **cache_ptr)
{
	if (!ws_log_msg_is_active(LOG_DOMAIN_DFILTER, level))
		return;

	char *str = dump_syntax_tree_str(root);

	ws_log_write_always_full(LOG_DOMAIN_DFILTER, level, NULL, -1, NULL,
				"%s:\n%s", msg, str);

	if (cache_ptr) {
		*cache_ptr = str;
	}
	else {
		g_free(str);
	}
}

/*
 * 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:
 */