/* Prosody IM

-- Copyright (C) 2008-2016 Matthew Wild

-- Copyright (C) 2008-2016 Waqas Hussain

-- Copyright (C) 2016 Kim Alvefur

--

-- This project is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

*/

/*

* crand.c

* C PRNG interface

*/

#include "lualib.h"

#include "lauxlib.h"

#include <string.h>

#include <errno.h>

/*

 * TODO: Decide on fixed size or dynamically allocated buffer

 */

#if 1

#include <stdlib.h>

#else

#define BUFLEN 256

#endif

#if defined(WITH_GETRANDOM)

#include <unistd.h>

#include <sys/syscall.h>

#include <linux/random.h>

#ifndef SYS_getrandom

#error getrandom() requires Linux 3.17 or later

#endif

/* Was this not supposed to be a function? */

int getrandom(char *buf, size_t len, int flags) {

	return syscall(SYS_getrandom, buf, len, flags);

}

#elif defined(WITH_ARC4RANDOM)

#include <stdlib.h>

#elif defined(WITH_OPENSSL)

#include <openssl/rand.h>

#else

#error util.crand compiled without a random source

#endif

int Lrandom(lua_State *L) {

#ifdef BUFLEN

	unsigned char buf[BUFLEN];

#else

	unsigned char *buf;

#endif

	int ret = 0;

	size_t len = (size_t)luaL_checkint(L, 1);

#ifdef BUFLEN

	len = len > BUFLEN ? BUFLEN : len;

#else

	buf = malloc(len);

	if(buf == NULL) {

		lua_pushnil(L);

		lua_pushstring(L, "out of memory");

		/* or it migth be better to

		 * return lua_error(L);

		 */

		return 2;

	}

#endif

#if defined(WITH_GETRANDOM)

	ret = getrandom(buf, len, 0);

	if(ret < 0) {

#ifndef BUFLEN

		free(buf);

#endif

		lua_pushnil(L);

		lua_pushstring(L, strerror(errno));

		lua_pushinteger(L, errno);

		return 3;

	}

#elif defined(WITH_ARC4RANDOM)

	arc4random_buf(buf, len);

	ret = len;

#elif defined(WITH_OPENSSL)

	ret = RAND_bytes(buf, len);

	if(ret == 1) {

		ret = len;

	} else {

#ifndef BUFLEN

		free(buf);

#endif

		lua_pushnil(L);

		lua_pushstring(L, "failed");

		/* lua_pushinteger(L, ERR_get_error()); */

		return 2;

	}

#endif

#ifndef BUFLEN

	free(buf);

#endif

	return 1;

}

#ifdef ENABLE_SEEDING

int Lseed(lua_State *L) {

	size_t len;

	const char *seed = lua_tolstring(L, 1, &len);

#if defined(WITH_OPENSSL)

	RAND_add(seed, len, len);

	return 0;

#else

	lua_pushnil(L);

	lua_pushliteral(L, "not-supported");

	return 2;

#endif

}

#endif

int luaopen_util_crand(lua_State *L) {

	lua_newtable(L);

	lua_pushcfunction(L, Lrandom);

	lua_setfield(L, -2, "bytes");

#ifdef ENABLE_SEEDING

	lua_pushcfunction(L, Lseed);

	lua_setfield(L, -2, "seed");

#endif

#if defined(WITH_GETRANDOM)

	lua_pushstring(L, "Linux");

#elif defined(WITH_ARC4RANDOM)

	lua_pushstring(L, "arc4random()");

#elif defined(WITH_OPENSSL)

	lua_pushstring(L, "OpenSSL");

#endif

	lua_setfield(L, -2, "_source");

#if defined(WITH_OPENSSL) && defined(_WIN32)

	/* Do we need to seed this on Windows? */

#endif

	return 1;

}