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/* 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)
#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 size_t len = luaL_checkinteger(L, 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;
}
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