hooks.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#ifdef WITH_LUA
# include <stdarg.h>
# include <stdint.h>
# include "util.h"
# include "udata.h"
# include "hooks.h"
# include <lua.h>
# include <lualib.h>
# include <lauxlib.h>
# include "gcache.h"
# include "json.h"
# include "version.h"

static int otr_log(lua_State *lua);
static int otr_strftime(lua_State *lua);
static int otr_putdb(lua_State *lua);
static int otr_getdb(lua_State *lua);

static struct gcache *LuaDB = NULL;

/*
 * Invoke the function `name' in the Lua script, which _may_ return
 * an integer that we, in turn, return to caller.
 */

static int l_function(lua_State *L, char *name)
{
	int rc = 0;

	lua_getglobal(L, name);
	if (lua_type(L, -1) != LUA_TFUNCTION) {
		olog(LOG_ERR, "Cannot invoke Lua function %s: %s\n", name, lua_tostring(L, -1));
		rc = 1;
	} else {
		lua_call(L, 0, 1);
		rc = (int)lua_tonumber(L, -1);
		lua_pop(L, 1);
	}
	lua_settop(L, 0);
	return (rc);
}

struct luadata *hooks_init(struct udata *ud, char *script)
{
	struct luadata *ld;
	int rc;

	if ((ld = malloc(sizeof(struct luadata))) == NULL)
		return (NULL);

	ld->script = strdup(script);
	// ld->L = lua_open();
	ld->L = luaL_newstate();
	luaL_openlibs(ld->L);

	/*
	 * Set up a global with some values.
	 */

	lua_newtable(ld->L);
		lua_pushstring(ld->L, VERSION);
		lua_setfield(ld->L, -2, "version");

		// lua_pushstring(ld->L, "/Users/jpm/Auto/projects/on-github/owntracks/recorder/lua");
		// lua_setfield(ld->L, -2, "luapath");

		lua_pushcfunction(ld->L, otr_log);
		lua_setfield(ld->L, -2, "log");

		lua_pushcfunction(ld->L, otr_strftime);
		lua_setfield(ld->L, -2, "strftime");

		lua_pushcfunction(ld->L, otr_putdb);
		lua_setfield(ld->L, -2, "putdb");

		lua_pushcfunction(ld->L, otr_getdb);
		lua_setfield(ld->L, -2, "getdb");

	lua_setglobal(ld->L, "otr");

#ifdef WITH_LMDB
	LuaDB = ud->luadb;
#endif

	olog(LOG_DEBUG, "initializing Lua hooks from `%s'", script);

	/* Load the Lua script */
	if (luaL_dofile(ld->L, ld->script)) {
		olog(LOG_ERR, "Cannot load Lua from %s: %s", ld->script, lua_tostring(ld->L, -1));
		hooks_exit(ld, "failed to load script");
		return (NULL);
	}

	rc = l_function(ld->L, "otr_init");
	if (rc != 0) {

		/*
		 * After all this work (sigh), the Script has decided we shouldn't use
		 * hooks, so unload the whole Lua stuff and NULL back.
		 */

		hooks_exit(ld, "otr_init() returned non-zero");
		ld = NULL;
	}

	return (ld);
}

void hooks_exit(struct luadata *ld, char *reason)
{
	if (ld) {
		l_function(ld->L, "otr_exit");
		olog(LOG_DEBUG, "unloading Lua: %s", reason);
		free(ld->script);
		lua_close(ld->L);
		free(ld);
	}
}

static void do_hook(char *hookname, struct udata *ud, char *topic, JsonNode *fullo)
{
	struct luadata *ld = ud->luadata;
	char *_type = "unknown";
	JsonNode *j;

	lua_settop(ld->L, 0);
	lua_getglobal(ld->L, hookname);
	if (lua_type(ld->L, -1) != LUA_TFUNCTION) {
		olog(LOG_NOTICE, "cannot invoke %s in Lua script", hookname);
		return;
	}

	lua_pushstring(ld->L, topic);			/* arg1: topic */

	if ((j = json_find_member(fullo, "_type")) != NULL) {
		if (j->tag == JSON_STRING)
			_type = j->string_;
	}

	lua_pushstring(ld->L, _type);			/* arg2: record type */

	lua_newtable(ld->L);				/* arg3: table */
	json_foreach(j, fullo) {
		lua_pushstring(ld->L, j->key);		/* table key */
		if (j->tag == JSON_STRING) {
			lua_pushstring(ld->L, j->string_);
		} else if (j->tag == JSON_NUMBER) {
			lua_pushnumber(ld->L, j->number_);
		} else if (j->tag == JSON_NULL) {
			lua_pushnil(ld->L);
		} else if (j->tag == JSON_BOOL) {
			lua_pushboolean(ld->L, j->bool_);
		}
		lua_rawset(ld->L, -3);

	}

	/* Invoke `hook' function in Lua with our args */
	if (lua_pcall(ld->L, 3, 1, 0)) {
		olog(LOG_ERR, "Failed to run script: %s", lua_tostring(ld->L, -1));
		exit(1);
	}

	// rc = (int)lua_tonumber(ld->L, -1);
	// printf("C: FILTER returns %d\n", rc);
}

static void hooks_hooklet(struct udata *ud, char *topic, JsonNode *fullo)
{
	JsonNode *j;
	struct luadata *ld = ud->luadata;
	char hookname[BUFSIZ];

	json_foreach(j, fullo) {
		snprintf(hookname, sizeof(hookname), "hooklet_%s", j->key);
		lua_getglobal(ld->L, hookname);
		if (lua_type(ld->L, -1) == LUA_TFUNCTION) {
			do_hook(hookname, ud, topic, fullo);
		}
	}
}

/*
 * Invoked from putrec() in storage. If the Lua putrec function is available
 * and it returns non-zero, do not putrec.
 */

int hooks_norec(struct udata *ud, char *user, char *device, char *payload)
{
	struct luadata *ld = ud->luadata;
	int rc;

	if (ld == NULL)
		return (0);

	lua_settop(ld->L, 0);
	lua_getglobal(ld->L, "otr_putrec");
	if (lua_type(ld->L, -1) != LUA_TFUNCTION) {
		return (0);
	}

	lua_pushstring(ld->L, user);
	lua_pushstring(ld->L, device);
	lua_pushstring(ld->L, payload);

	/* Invoke Lua function with our args */
	if (lua_pcall(ld->L, 3, 1, 0)) {
		olog(LOG_ERR, "Failed to run putrec in Lua: %s", lua_tostring(ld->L, -1));
		exit(1);
	}

	rc = (int)lua_tonumber(ld->L, -1);
	return (rc);
}

void hooks_hook(struct udata *ud, char *topic, JsonNode *fullo)
{
	do_hook("otr_hook", ud, topic, fullo);
	hooks_hooklet(ud, topic, fullo);
}

/*
 * --- Here come the functions we provide to Lua scripts.
 */

static int otr_log(lua_State *lua)
{
	const char *str;

	if (lua_gettop(lua) >= 1) {
		str =  lua_tostring(lua, 1);
		olog(LOG_INFO, "%s", str);
		lua_pop(lua, 1);
	}
	return 0;
}

/*
 * otr.strftime(format, seconds)
 * Perform a strtime(3) for Lua with the specified format and
 * seconds, and return the string result to Lua. As a special
 * case, if `seconds' is negative, use current time.
 */

static int otr_strftime(lua_State *lua)
{
	const char *fmt;
	long secs;
	struct tm *tm;
	char buf[BUFSIZ];

	if (lua_gettop(lua) >= 1) {
		fmt =  lua_tostring(lua, 1);
		if ((secs =  lua_tonumber(lua, 2)) < 1)
			secs = time(0);

		if ((tm = gmtime(&secs)) != NULL) {
			strftime(buf, sizeof(buf), fmt, tm);

			lua_pushstring(lua, buf);
			return (1);
		}
	}
	return (0);
}

/*
 * Requires two string arguments: key, value
 * These are written into the named LMDB database
 * called `luadb'.
 */

static int otr_putdb(lua_State *lua)
{
	const char *key, *value;
	int rc = 0;

	if (lua_gettop(lua) >= 1) {
		key =  lua_tostring(lua, 1);
		value =  lua_tostring(lua, 2);

		rc = gcache_put(LuaDB, (char *)key, (char *)value);
		// olog(LOG_DEBUG, "LUA_PUT (%s, %s) == %d\n", key, value, rc);
	}
	return (rc);
}

static int otr_getdb(lua_State *lua)
{
	char buf[BUFSIZ];
	const char *key;
	int rc = 0, blen;

	if (lua_gettop(lua) >= 1) {
		key =  lua_tostring(lua, 1);

		blen = gcache_get(LuaDB, (char *)key, buf, sizeof(buf));
		if (blen < 0)
			memset(buf, 0, sizeof(buf));
		// printf("K=[%s], blen=%d\n", key, blen);
		lua_pushstring(lua, buf);
		rc = 1;
	}
	return (rc);
}
#endif /* WITH_LUA */