hlua_fcn.c

/*
 * Lua safe functions
 *
 * Copyright 2015-2016 Thierry Fournier <tfournier@arpalert.org>
 *
 * 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.
 *
 *
 * All the functions in this file runs with a Lua stack, and can
 * return with a longjmp. All of these function must be launched
 * in an environment able to catch a longjmp, otherwise a
 * critical error can be raised.
 */

#define _GNU_SOURCE

#include <lauxlib.h>
#include <lua.h>
#include <lualib.h>

#include <import/ebmbtree.h>

#include <haproxy/cli-t.h>
#include <haproxy/errors.h>
#include <haproxy/hlua.h>
#include <haproxy/hlua_fcn.h>
#include <haproxy/http.h>
#include <haproxy/net_helper.h>
#include <haproxy/pattern.h>
#include <haproxy/protocol.h>
#include <haproxy/proxy.h>
#include <haproxy/regex.h>
#include <haproxy/server.h>
#include <haproxy/stats.h>
#include <haproxy/stick_table.h>
#include <haproxy/event_hdl.h>
#include <haproxy/stream-t.h>
#include <haproxy/time.h>
#include <haproxy/tools.h>
#include <haproxy/mailers.h>

/* Contains the class reference of the concat object. */
static int class_concat_ref;
static int class_queue_ref;
static int class_proxy_ref;
static int class_server_ref;
static int class_listener_ref;
static int class_event_sub_ref;
static int class_patref_ref;
static int class_regex_ref;
static int class_stktable_ref;
static int class_proxy_list_ref;
static int class_server_list_ref;

#define STATS_LEN (MAX((int)ST_I_PX_MAX, (int)ST_I_INF_MAX))

static THREAD_LOCAL struct field stats[STATS_LEN];

int hlua_checkboolean(lua_State *L, int index)
{
	if (!lua_isboolean(L, index))
		luaL_argerror(L, index, "boolean expected");
	return lua_toboolean(L, index);
}

/* Helper to push unsigned integers to Lua stack, respecting Lua limitations  */
static int hlua_fcn_pushunsigned(lua_State *L, unsigned int val)
{
#if (LUA_MAXINTEGER == LLONG_MAX || ((LUA_MAXINTEGER == LONG_MAX) && (__WORDSIZE == 64)))
	lua_pushinteger(L, val);
#else
	if (val > INT_MAX)
		lua_pushnumber(L, (lua_Number)val);
	else
		lua_pushinteger(L, (int)val);
#endif
	return 1;
}

/* Helper to push unsigned long long to Lua stack, respecting Lua limitations  */
static int hlua_fcn_pushunsigned_ll(lua_State *L, unsigned long long val) {
#if (LUA_MAXINTEGER == LLONG_MAX || ((LUA_MAXINTEGER == LONG_MAX) && (__WORDSIZE == 64)))
	/* 64 bits case, U64 is supported until LLONG_MAX */
	if (val > LLONG_MAX)
		lua_pushnumber(L, (lua_Number)val);
	else
		lua_pushinteger(L, val);
#else
	/* 32 bits case, U64 is supported until INT_MAX */
	if (val > INT_MAX)
		lua_pushnumber(L, (lua_Number)val);
	else
		lua_pushinteger(L, (int)val);
#endif
	return 1;
}

/* This function gets a struct field and converts it in Lua
 * variable. The variable is pushed at the top of the stack.
 */
int hlua_fcn_pushfield(lua_State *L, struct field *field)
{
	/* The lua_Integer is always signed. Its length depends on
	 * compilation options, so the following code is conditioned
	 * by some macros. Windows maros are not supported.
	 * If the number cannot be represented as integer, we try to
	 * convert to float.
	 */
	switch (field_format(field, 0)) {

	case FF_EMPTY:
		lua_pushnil(L);
		return 1;

	case FF_S32:
		/* S32 is always supported. */
		lua_pushinteger(L, field->u.s32);
		return 1;

	case FF_U32:
#if (LUA_MAXINTEGER == LLONG_MAX || ((LUA_MAXINTEGER == LONG_MAX) && (__WORDSIZE == 64)))
		/* 64 bits case, U32 is always supported */
		lua_pushinteger(L, field->u.u32);
#else
		/* 32 bits case, U32 is supported until INT_MAX. */
		if (field->u.u32 > INT_MAX)
			lua_pushnumber(L, (lua_Number)field->u.u32);
		else
			lua_pushinteger(L, field->u.u32);
#endif
		return 1;

	case FF_S64:
#if (LUA_MAXINTEGER == LLONG_MAX || ((LUA_MAXINTEGER == LONG_MAX) && (__WORDSIZE == 64)))
		/* 64 bits case, S64 is always supported */
		lua_pushinteger(L, field->u.s64);
#else
		/* 64 bits case, S64 is supported between INT_MIN and INT_MAX */
		if (field->u.s64 < INT_MIN || field->u.s64 > INT_MAX)
			lua_pushnumber(L, (lua_Number)field->u.s64);
		else
			lua_pushinteger(L, (int)field->u.s64);
#endif
		return 1;

	case FF_U64:
#if (LUA_MAXINTEGER == LLONG_MAX || ((LUA_MAXINTEGER == LONG_MAX) && (__WORDSIZE == 64)))
		/* 64 bits case, U64 is supported until LLONG_MAX */
		if (field->u.u64 > LLONG_MAX)
			lua_pushnumber(L, (lua_Number)field->u.u64);
		else
			lua_pushinteger(L, field->u.u64);
#else
		/* 64 bits case, U64 is supported until INT_MAX */
		if (field->u.u64 > INT_MAX)
			lua_pushnumber(L, (lua_Number)field->u.u64);
		else
			lua_pushinteger(L, (int)field->u.u64);
#endif
		return 1;

	case FF_STR:
		lua_pushstring(L, field->u.str);
		return 1;

	default:
		break;
	}

	/* Default case, never reached. */
	lua_pushnil(L);
	return 1;
}

/* Some string are started or terminated by blank chars,
 * this function removes the spaces, tabs, \r and
 * \n at the begin and at the end of the string "str", and
 * push the result in the lua stack.
 * Returns a pointer to the Lua internal copy of the string.
 */
const char *hlua_pushstrippedstring(lua_State *L, const char *str)
{
	const char *p;
	int l;

	for (p = str; HTTP_IS_LWS(*p); p++);

	for (l = strlen(p); l && HTTP_IS_LWS(p[l-1]); l--);

	return lua_pushlstring(L, p, l);
}

/* The three following functions are useful for adding entries
 * in a table. These functions takes a string and respectively an
 * integer, a string or a function and add it to the table in the
 * top of the stack.
 *
 * These functions throws an error if no more stack size is
 * available.
 */
void hlua_class_const_int(lua_State *L, const char *name, int value)
{
	lua_pushstring(L, name);
	lua_pushinteger(L, value);
	lua_rawset(L, -3);
}
void hlua_class_const_str(lua_State *L, const char *name, const char *value)
{
	lua_pushstring(L, name);
	lua_pushstring(L, value);
	lua_rawset(L, -3);
}
void hlua_class_function(lua_State *L, const char *name, int (*function)(lua_State *L))
{
	lua_pushstring(L, name);
	lua_pushcclosure(L, function, 0);
	lua_rawset(L, -3);
}

/* This function returns a string containing the HAProxy object name. */
int hlua_dump_object(struct lua_State *L)
{
	const char *name = (const char *)lua_tostring(L, lua_upvalueindex(1));
	lua_pushfstring(L, "HAProxy class %s", name);
	return 1;
}

/* This function register a table as metatable and. It names
 * the metatable, and returns the associated reference.
 * The original table is popped from the top of the stack.
 * "name" is the referenced class name.
 */
int hlua_register_metatable(struct lua_State *L, char *name)
{
	/* Check the type of the top element. it must be
	 * a table.
	 */
	if (lua_type(L, -1) != LUA_TTABLE)
		luaL_error(L, "hlua_register_metatable() requires a type Table "
		              "in the top of the stack");

	/* Add the __tostring function which identify the
	 * created object.
	 */
	lua_pushstring(L, "__tostring");
	lua_pushstring(L, name);
	lua_pushcclosure(L, hlua_dump_object, 1);
	lua_rawset(L, -3);

	/* Register a named entry for the table. The table
	 * reference is copied first because the function
	 * lua_setfield() pop the entry.
	 */
	lua_pushvalue(L, -1);
	lua_setfield(L, LUA_REGISTRYINDEX, name);

	/* Creates the reference of the object. The
	 * function luaL_ref pop the top of the stack.
	 */
	return luaL_ref(L, LUA_REGISTRYINDEX);
}

/* Return an object of the expected type, or throws an error. */
void *hlua_checkudata(lua_State *L, int ud, int class_ref)
{
	void *p;
	int ret;

	/* Check if the stack entry is an array. */
	if (!lua_istable(L, ud))
		luaL_argerror(L, ud, NULL);

	/* pop the metatable of the referencecd object. */
	if (!lua_getmetatable(L, ud))
		luaL_argerror(L, ud, NULL);

	/* pop the expected metatable. */
	lua_rawgeti(L, LUA_REGISTRYINDEX, class_ref);

	/* Check if the metadata have the expected type. */
	ret = lua_rawequal(L, -1, -2);
	lua_pop(L, 2);
	if (!ret)
		luaL_argerror(L, ud, NULL);

	/* Push on the stack at the entry [0] of the table. */
	lua_rawgeti(L, ud, 0);

	/* Check if this entry is userdata. */
	p = lua_touserdata(L, -1);
	if (!p)
		luaL_argerror(L, ud, NULL);

	/* Remove the entry returned by lua_rawgeti(). */
	lua_pop(L, 1);

	/* Return the associated struct. */
	return p;
}

/* This function return the current date at epoch format in milliseconds. */
int hlua_now(lua_State *L)
{
	/* WT: the doc says "returns the current time" and later says that it's
	 * monotonic. So the best fit is to use start_date+(now-start_time).
	 */
	struct timeval tv;

	tv = NS_TO_TV(now_ns - start_time_ns);
	tv_add(&tv, &tv, &start_date);

	lua_newtable(L);
	lua_pushstring(L, "sec");
	lua_pushinteger(L, tv.tv_sec);
	lua_rawset(L, -3);
	lua_pushstring(L, "usec");
	lua_pushinteger(L, tv.tv_usec);
	lua_rawset(L, -3);
	return 1;
}

/* This functions expects a Lua string as HTTP date, parse it and
 * returns an integer containing the epoch format of the date, or
 * nil if the parsing fails.
 */
static int hlua_parse_date(lua_State *L, int (*fcn)(const char *, int, struct tm*))
{
	const char *str;
	size_t len;
	struct tm tm;
	time_t time;

	str = luaL_checklstring(L, 1, &len);

	if (!fcn(str, len, &tm)) {
		lua_pushnil(L);
		return 1;
	}

	/* This function considers the content of the broken-down time
	 * is exprimed in the UTC timezone. timegm don't care about
	 * the gnu variable tm_gmtoff. If gmtoff is set, or if you know
	 * the timezone from the broken-down time, it must be fixed
	 * after the conversion.
	 */
	time = my_timegm(&tm);
	if (time == -1) {
		lua_pushnil(L);
		return 1;
	}

	lua_pushinteger(L, (int)time);
	return 1;
}
static int hlua_http_date(lua_State *L)
{
	return hlua_parse_date(L, parse_http_date);
}
static int hlua_imf_date(lua_State *L)
{
	return hlua_parse_date(L, parse_imf_date);
}
static int hlua_rfc850_date(lua_State *L)
{
	return hlua_parse_date(L, parse_rfc850_date);
}
static int hlua_asctime_date(lua_State *L)
{
	return hlua_parse_date(L, parse_asctime_date);
}

static int hlua_get_info(lua_State *L)
{
	int i;

	stats_fill_info(stats, STATS_LEN, 0);

	lua_newtable(L);
	for (i=0; i<ST_I_INF_MAX; i++) {
		lua_pushstring(L, stat_cols_info[i].name);
		hlua_fcn_pushfield(L, &stats[i]);
		lua_settable(L, -3);
	}
	return 1;
}

static struct hlua_concat *hlua_check_concat(lua_State *L, int ud)
{
	return (hlua_checkudata(L, ud, class_concat_ref));
}

static int hlua_concat_add(lua_State *L)
{
	struct hlua_concat *b;
	char *buffer;
	char *new;
	const char *str;
	size_t l;

	/* First arg must be a concat object. */
	b = hlua_check_concat(L, 1);

	/* Second arg must be a string. */
	str = luaL_checklstring(L, 2, &l);

	/* Get the buffer. */
	lua_rawgeti(L, 1, 1);
	buffer = lua_touserdata(L, -1);
	lua_pop(L, 1);

	/* Update the buffer size if it s required. The old buffer
	 * is crushed by the new in the object array, so it will
	 * be deleted by the GC.
	 * Note that in the first loop, the "new" variable is only
	 * used as a flag.
	 */
	new = NULL;
	while (b->size - b->len < l) {
		b->size += HLUA_CONCAT_BLOCSZ;
		new = buffer;
	}
	if (new) {
		new = lua_newuserdata(L, b->size);
		memcpy(new, buffer, b->len);
		lua_rawseti(L, 1, 1);
		buffer = new;
	}

	/* Copy string, and update metadata. */
	memcpy(buffer + b->len, str, l);
	b->len += l;
	return 0;
}

static int hlua_concat_dump(lua_State *L)
{
	struct hlua_concat *b;
	char *buffer;

	/* First arg must be a concat object. */
	b = hlua_check_concat(L, 1);

	/* Get the buffer. */
	lua_rawgeti(L, 1, 1);
	buffer = lua_touserdata(L, -1);
	lua_pop(L, 1);

	/* Push the soncatenated string in the stack. */
	lua_pushlstring(L, buffer, b->len);
	return 1;
}

int hlua_concat_new(lua_State *L)
{
	struct hlua_concat *b;

	lua_newtable(L);
	b = lua_newuserdata(L, sizeof(*b));
	b->size = HLUA_CONCAT_BLOCSZ;
	b->len = 0;
	lua_rawseti(L, -2, 0);
	lua_newuserdata(L, HLUA_CONCAT_BLOCSZ);
	lua_rawseti(L, -2, 1);

	lua_rawgeti(L, LUA_REGISTRYINDEX, class_concat_ref);
	lua_setmetatable(L, -2);

	return 1;
}

static int concat_tostring(lua_State *L)
{
	const void *ptr = lua_topointer(L, 1);
	lua_pushfstring(L, "Concat object: %p", ptr);
	return 1;
}

static void hlua_concat_init(lua_State *L)
{
	/* Creates the buffered concat object. */
	lua_newtable(L);

	lua_pushstring(L, "__tostring");
	lua_pushcclosure(L, concat_tostring, 0);
	lua_settable(L, -3);

	lua_pushstring(L, "__index"); /* Creates the index entry. */
	lua_newtable(L); /* The "__index" content. */

	lua_pushstring(L, "add");
	lua_pushcclosure(L, hlua_concat_add, 0);
	lua_settable(L, -3);

	lua_pushstring(L, "dump");
	lua_pushcclosure(L, hlua_concat_dump, 0);
	lua_settable(L, -3);

	lua_settable(L, -3); /* Sets the __index entry. */
	class_concat_ref = luaL_ref(L, LUA_REGISTRYINDEX);
}

/* C backing storage for lua Queue class */
struct hlua_queue {
	uint32_t size;
	struct mt_list list;
	struct mt_list wait_tasks;
};

/* used to store lua objects in queue->list */
struct hlua_queue_item {
	int ref; /* lua object reference id */
	struct mt_list list;
};

/* This is the memory pool containing struct hlua_queue_item (queue items)
 */
DECLARE_STATIC_TYPED_POOL(pool_head_hlua_queue, "hlua_queue", struct hlua_queue_item);

static struct hlua_queue *hlua_check_queue(lua_State *L, int ud)
{
	return hlua_checkudata(L, ud, class_queue_ref);
}

/* queue:size(): returns an integer containing the current number of queued
 * items.
 */
static int hlua_queue_size(lua_State *L)
{
	struct hlua_queue *queue = hlua_check_queue(L, 1);

	BUG_ON(!queue);
	lua_pushinteger(L, HA_ATOMIC_LOAD(&queue->size));

	return 1;
}

/* queue:alarm(): (re)arms queue waiting alarm so that the current
 * Lua task is woken up on new queue events
 */
static int hlua_queue_alarm(lua_State *L)
{
	struct hlua_queue *queue = hlua_check_queue(L, 1);

	struct hlua *hlua;

	BUG_ON(!queue);

	/* Get hlua struct, or NULL if we execute from main lua state */
	hlua = hlua_gethlua(L);

	if (!hlua || HLUA_CANT_YIELD(hlua)) {
		luaL_error(L, "alarm() may only be used within task context "
			      "(requires yielding)");
		return 0; /* not reached */
	}

	if (!notification_new(&hlua->com, &queue->wait_tasks, hlua->task))
		luaL_error(L, "out of memory");

	return 0;
}

/* queue:push(): push an item (any type, except nil) at the end of the queue
 *
 * Returns boolean:true for success and boolean:false on error
 */
static int hlua_queue_push(lua_State *L)
{
	struct hlua_queue *queue = hlua_check_queue(L, 1);
	struct hlua_queue_item *item;

	if (lua_gettop(L) != 2 || lua_isnoneornil(L, 2)) {
		luaL_error(L, "unexpected argument");
		/* not reached */
		return 0;
	}
	BUG_ON(!queue);

	item = pool_alloc(pool_head_hlua_queue);
	if (!item) {
		/* memory error */
		lua_pushboolean(L, 0);
		return 1;
	}

	/* get a reference from lua object at the top of the stack */
	item->ref = hlua_ref(L);

	/* push new entry to the queue */
	MT_LIST_INIT(&item->list);
	HA_ATOMIC_INC(&queue->size);
	MT_LIST_APPEND(&queue->list, &item->list);

	/* notify tasks waiting on queue:pop_wait() (if any) */
	notification_wake(&queue->wait_tasks);

	lua_pushboolean(L, 1);
	return 1;
}

/* internal queue pop helper, returns 1 if it successfully popped an item
 * from the queue and pushed it on lua stack.
 *
 * Else it returns 0 (nothing is pushed on the stack)
 */
static int _hlua_queue_pop(lua_State *L, struct hlua_queue *queue)
{
	struct hlua_queue_item *item;

	item = MT_LIST_POP(&queue->list, typeof(item), list);
	if (!item)
		return 0; /* nothing in queue */

	HA_ATOMIC_DEC(&queue->size);
	/* push lua obj on the stack */
	hlua_pushref(L, item->ref);

	/* obj ref should be released right away since it was pushed
	 * on the stack and will not be used anymore
	 */
	hlua_unref(L, item->ref);

	/* free the queue item */
	pool_free(pool_head_hlua_queue, item);

	return 1;
}

/* queue:pop(): returns the first item at the top of que queue or nil if
 * the queue is empty.
 */
static int hlua_queue_pop(lua_State *L)
{
	struct hlua_queue *queue = hlua_check_queue(L, 1);

	BUG_ON(!queue);
	if (!_hlua_queue_pop(L, queue)) {
		/* nothing in queue, push nil */
		lua_pushnil(L);
	}
	return 1; /* either item or nil is at the top of the stack */
}

/* queue:pop_wait(): same as queue:pop() but doesn't return on empty queue.
 *
 * Aborts if used incorrectly and returns nil in case of memory error.
 */
static int _hlua_queue_pop_wait(lua_State *L, int status, lua_KContext ctx)
{
	struct hlua_queue *queue = hlua_check_queue(L, 1);

	/* new pop attempt */
	if (!_hlua_queue_pop(L, queue)) {
		struct hlua *hlua;

		hlua = hlua_gethlua(L);
		if (!notification_new(&hlua->com, &queue->wait_tasks, hlua->task)) {
			lua_pushnil(L);
			return 1; /* memory error, return nil */
		}
		hlua_yieldk(L, 0, 0, _hlua_queue_pop_wait, TICK_ETERNITY, 0); // wait retry
		return 0; // never reached, yieldk won't return
	}

	return 1; // success
}
static int hlua_queue_pop_wait(lua_State *L)
{
	struct hlua_queue *queue = hlua_check_queue(L, 1);
	struct hlua *hlua;

	BUG_ON(!queue);

	/* Get hlua struct, or NULL if we execute from main lua state */
	hlua = hlua_gethlua(L);

	if (!hlua || HLUA_CANT_YIELD(hlua)) {
		luaL_error(L, "pop_wait() may only be used within task context "
			      "(requires yielding)");
		return 0; /* not reached */
	}

	/* try opportunistic pop (there could already be pending items) */
	if (_hlua_queue_pop(L, queue))
		return 1; // success

	/* no pending items, waiting required */

	/* Go to waiting loop which immediately performs a new attempt to make
	 * sure we didn't miss a push during the wait entry initialization.
	 *
	 * _hlua_queue_pop_wait() won't return to us if it has to yield, which
	 * is the most likely scenario. What happens in this case is that yieldk
	 * call never returns, and instead Lua will call the continuation
	 * function after a successful resume, so the calling function will
	 * no longer be us, but Lua instead. And when the continuation function
	 * eventually returns (because it successfully popped an item), Lua will
	 * directly give the hand back to the Lua function that called us.
	 *
	 * More info here: https://www.lua.org/manual/5.4/manual.html#4.7
	 */
	return _hlua_queue_pop_wait(L, LUA_OK, 0);
}

static int hlua_queue_new(lua_State *L)
{
	struct hlua_queue *q;

	lua_newtable(L);

	/* set class metatable */
	lua_rawgeti(L, LUA_REGISTRYINDEX, class_queue_ref);
	lua_setmetatable(L, -2);

	/* index:0 is queue userdata (c data) */
	q = lua_newuserdata(L, sizeof(*q));
	MT_LIST_INIT(&q->list);
	MT_LIST_INIT(&q->wait_tasks);
	q->size = 0;
	lua_rawseti(L, -2, 0);

	/* class methods */
	hlua_class_function(L, "size", hlua_queue_size);
	hlua_class_function(L, "pop", hlua_queue_pop);
	hlua_class_function(L, "pop_wait", hlua_queue_pop_wait);
	hlua_class_function(L, "push", hlua_queue_push);
	hlua_class_function(L, "alarm", hlua_queue_alarm);

	return 1;
}

static int hlua_queue_gc(struct lua_State *L)
{
	struct hlua_queue *queue = hlua_check_queue(L, 1);
	struct hlua_queue_item *item;

	/* purge remaining (unconsumed) items in the queue */
	while ((item = MT_LIST_POP(&queue->list, typeof(item), list))) {
		/* free the queue item */
		pool_free(pool_head_hlua_queue, item);
	}

	/* queue (userdata) will automatically be freed by lua gc */

	return 0;
}

static void hlua_queue_init(lua_State *L)
{
	/* Creates the queue object. */
	lua_newtable(L);

	hlua_class_function(L, "__gc", hlua_queue_gc);

	class_queue_ref = hlua_register_metatable(L, CLASS_QUEUE);
}

int hlua_fcn_new_stktable(lua_State *L, struct stktable *tbl)
{
	lua_newtable(L);

	/* Pop a class stktbl metatable and affect it to the userdata. */
	lua_rawgeti(L, LUA_REGISTRYINDEX, class_stktable_ref);
	lua_setmetatable(L, -2);

	lua_pushlightuserdata(L, tbl);
	lua_rawseti(L, -2, 0);
	return 1;
}

static struct stktable *hlua_check_stktable(lua_State *L, int ud)
{
	return hlua_checkudata(L, ud, class_stktable_ref);
}

/* Extract stick table attributes into Lua table */
int hlua_stktable_info(lua_State *L)
{
	struct stktable *tbl;
	int dt;

	tbl = hlua_check_stktable(L, 1);

	if (!tbl->id) {
		lua_pushnil(L);
		return 1;
	}

	lua_newtable(L);

	lua_pushstring(L, "type");
	lua_pushstring(L, stktable_types[tbl->type].kw);
	lua_settable(L, -3);

	lua_pushstring(L, "length");
	lua_pushinteger(L, tbl->key_size);
	lua_settable(L, -3);

	lua_pushstring(L, "size");
	hlua_fcn_pushunsigned(L, tbl->size);
	lua_settable(L, -3);

	lua_pushstring(L, "used");
	hlua_fcn_pushunsigned(L, tbl->current);
	lua_settable(L, -3);

	lua_pushstring(L, "nopurge");
	lua_pushboolean(L, (tbl->flags & STK_FL_NOPURGE));
	lua_settable(L, -3);

	lua_pushstring(L, "expire");
	lua_pushinteger(L, tbl->expire);
	lua_settable(L, -3);

	/* Save data types periods (if applicable) in 'data' table */
	lua_pushstring(L, "data");
	lua_newtable(L);

	for (dt = 0; dt < STKTABLE_DATA_TYPES; dt++) {
		if (tbl->data_ofs[dt] == 0)
			continue;

		lua_pushstring(L, stktable_data_types[dt].name);

		if (stktable_data_types[dt].arg_type == ARG_T_DELAY)
			lua_pushinteger(L, tbl->data_arg[dt].u);
		else
			lua_pushinteger(L, -1);

		lua_settable(L, -3);
	}

	lua_settable(L, -3);

	return 1;
}

/* Helper to get extract stick table entry into Lua table */
static void hlua_stktable_entry(lua_State *L, struct stktable *t, struct stksess *ts)
{
	int dt;
	void *ptr;

	for (dt = 0; dt < STKTABLE_DATA_TYPES; dt++) {

		ptr = stktable_data_ptr(t, ts, dt);
		if (!ptr)
			continue;

		lua_pushstring(L, stktable_data_types[dt].name);

		switch (stktable_data_types[dt].std_type) {
		case STD_T_SINT:
			lua_pushinteger(L, stktable_data_cast(ptr, std_t_sint));
			break;
		case STD_T_UINT:
			hlua_fcn_pushunsigned(L, stktable_data_cast(ptr, std_t_uint));
			break;
		case STD_T_ULL:
			hlua_fcn_pushunsigned_ll(L, stktable_data_cast(ptr, std_t_ull));
			break;
		case STD_T_FRQP:
			lua_pushinteger(L, read_freq_ctr_period(&stktable_data_cast(ptr, std_t_frqp),
			                t->data_arg[dt].u));
			break;
		case STD_T_DICT: {
			struct dict_entry *de;
			de = stktable_data_cast(ptr, std_t_dict);
			lua_pushstring(L, de ? (char *)de->value.key : "-");
			break;
		}
		}

		lua_settable(L, -3);
	}
}

/* Looks in table <t> for a sticky session matching key <key>
 * Returns table with session data or nil
 *
 * The returned table always contains 'use' and 'expire' (integer) fields.
 * For frequency/rate counters, each data entry is returned as table with
 * 'value' and 'period' fields.
 */
int hlua_stktable_lookup(lua_State *L)
{
	struct stktable *t;
	struct sample smp;
	struct stktable_key *skey;
	struct stksess *ts;

	t = hlua_check_stktable(L, 1);
	smp.data.type = SMP_T_STR;
	smp.flags = SMP_F_CONST;
	smp.data.u.str.area = (char *)lua_tolstring(L, 2, &smp.data.u.str.data);

	skey = smp_to_stkey(&smp, t);
	if (!skey) {
		lua_pushnil(L);
		return 1;
	}

	ts = stktable_lookup_key(t, skey);
	if (!ts) {
		lua_pushnil(L);
		return 1;
	}

	lua_newtable(L);
	lua_pushstring(L, "use");
	lua_pushinteger(L, HA_ATOMIC_LOAD(&ts->ref_cnt) - 1);
	lua_settable(L, -3);

	lua_pushstring(L, "expire");
	lua_pushinteger(L, tick_remain(now_ms, ts->expire));
	lua_settable(L, -3);

	hlua_stktable_entry(L, t, ts);
	HA_ATOMIC_DEC(&ts->ref_cnt);

	return 1;
}

struct stk_filter {
	long long val;
	int type;
	int op;
};


/* Helper for returning errors to callers using Lua convention (nil, err) */
static int hlua_error(lua_State *L, const char *fmt, ...)  {
	char buf[256];
	int len;
	va_list args;
	va_start(args, fmt);
        len = vsnprintf(buf, sizeof(buf), fmt, args);
	va_end(args);

	if (len < 0) {
		ha_alert("hlua_error(): Could not write error message.\n");
		lua_pushnil(L);
		return 1;
	} else if (len >= sizeof(buf))
		ha_alert("hlua_error(): Error message was truncated.\n");

	lua_pushnil(L);
	lua_pushstring(L, buf);

	return 2;
}

/* Dump the contents of stick table <t>*/
int hlua_stktable_dump(lua_State *L)
{
	struct stktable *t;
	struct ebmb_node *eb;
	struct ebmb_node *n;
	struct stksess *ts;
	int type;
	int op;
	int dt;
	long long val;
	struct stk_filter filter[STKTABLE_FILTER_LEN];
	int filter_count = 0;
	int i;
	int skip_entry;
	void *ptr;
	int bucket = 0; // FIXME: this should be stored in the context and iterate to scan the table

	t = hlua_check_stktable(L, 1);
	type = lua_type(L, 2);

	switch (type) {
	case LUA_TNONE:
	case LUA_TNIL:
		break;
	case LUA_TTABLE:
		lua_pushnil(L);
		while (lua_next(L, 2) != 0) {
			int entry_idx = 0;

			if (filter_count >= STKTABLE_FILTER_LEN)
				return hlua_error(L, "Filter table too large (len > %d)", STKTABLE_FILTER_LEN);

			if (lua_type(L, -1) != LUA_TTABLE  || lua_rawlen(L, -1) != 3)
				return hlua_error(L, "Filter table entry must be a triplet: {\"data_col\", \"op\", val} (entry #%d)", filter_count + 1);

			lua_pushnil(L);
			while (lua_next(L, -2) != 0) {
				switch (entry_idx) {
				case 0:
					if (lua_type(L, -1) != LUA_TSTRING)
						return hlua_error(L, "Filter table data column must be string (entry #%d)", filter_count + 1);

					dt = stktable_get_data_type((char *)lua_tostring(L, -1));
					if (dt < 0 || t->data_ofs[dt] == 0)