File

util-src/crand.c @ 11707:61759372be26

mod_s2s: Clone 'extra' data to let resolvers add more to it This way 'extra' is unique for each connect() instance, making it safer to mutate it, while inheriting the global settings. See 926d53af9a7a for some more context.
author Kim Alvefur <zash@zash.se>
date Sun, 18 Jul 2021 21:53:26 +0200
parent 8451:770f79a9635c
child 12470:80f3123053e2
line wrap: on
line source

/* Prosody IM
-- Copyright (C) 2008-2017 Matthew Wild
-- Copyright (C) 2008-2017 Waqas Hussain
-- Copyright (C) 2016-2017 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
*
* The purpose of this module is to provide access to a PRNG in
* environments without /dev/urandom
*
* Caution! This has not been extensively tested.
*
*/

#define _DEFAULT_SOURCE

#include <stdlib.h>
#include <string.h>
#include <errno.h>

#include "lualib.h"
#include "lauxlib.h"

#if defined(WITH_GETRANDOM)

#ifndef __GLIBC_PREREQ
/* Not compiled with glibc at all */
#define __GLIBC_PREREQ(a,b) 0
#endif

#if ! __GLIBC_PREREQ(2,25)
/* Not compiled with a glibc that provides getrandom() */
#include <unistd.h>
#include <sys/syscall.h>

#ifndef SYS_getrandom
#error getrandom() requires Linux 3.17 or later
#endif

/* This wasn't present before glibc 2.25 */
int getrandom(void *buf, size_t buflen, unsigned int flags) {
	return syscall(SYS_getrandom, buf, buflen, flags);
}
#else
#include <sys/random.h>
#endif

#elif defined(WITH_OPENSSL)
#include <openssl/rand.h>
#elif defined(WITH_ARC4RANDOM)
#ifdef __linux__
#include <bsd/stdlib.h>
#endif
#else
#error util.crand compiled without a random source
#endif

#ifndef SMALLBUFSIZ
#define SMALLBUFSIZ 32
#endif

int Lrandom(lua_State *L) {
	char smallbuf[SMALLBUFSIZ];
	char *buf = &smallbuf[0];
	const lua_Integer l = luaL_checkinteger(L, 1);
	const size_t len = l;
	luaL_argcheck(L, l >= 0, 1, "must be > 0");

	if(len == 0) {
		lua_pushliteral(L, "");
		return 1;
	}

	if(len > SMALLBUFSIZ) {
		buf = lua_newuserdata(L, len);
	}

#if defined(WITH_GETRANDOM)
	/*
	 * This acts like a read from /dev/urandom with the exception that it
	 * *does* block if the entropy pool is not yet initialized.
	 */
	int left = len;
	char *p = buf;

	do {
		int ret = getrandom(p, left, 0);

		if(ret < 0) {
			lua_pushstring(L, strerror(errno));
			return lua_error(L);
		}

		p += ret;
		left -= ret;
	} while(left > 0);

#elif defined(WITH_ARC4RANDOM)
	arc4random_buf(buf, len);
#elif defined(WITH_OPENSSL)

	if(!RAND_status()) {
		lua_pushliteral(L, "OpenSSL PRNG not seeded");
		return lua_error(L);
	}

	if(RAND_bytes((unsigned char *)buf, len) != 1) {
		/* TODO ERR_get_error() */
		lua_pushstring(L, "RAND_bytes() failed");
		return lua_error(L);
	}

#endif

	lua_pushlstring(L, buf, len);
	return 1;
}

int luaopen_util_crand(lua_State *L) {
#if (LUA_VERSION_NUM > 501)
	luaL_checkversion(L);
#endif

	lua_createtable(L, 0, 2);
	lua_pushcfunction(L, Lrandom);
	lua_setfield(L, -2, "bytes");

#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");

	return 1;
}