1 files changed, 118 insertions, 0 deletions
diff --git a/util-src/crand.c b/util-src/crand.c
new file mode 100644
index 00000000..ef9da4d2
--- /dev/null
+++ b/util-src/crand.c
@@ -0,0 +1,118 @@
+/* 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 "lualib.h"
+#include "lauxlib.h"
+
+#include <string.h>
+#include <errno.h>
+
+#if defined(WITH_GETRANDOM)
+
+#if ! __GLIBC_PREREQ(2,25)
+#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_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) {
+	int ret = 0;
+	size_t len = (size_t)luaL_checkinteger(L, 1);
+	void *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.
+	 */
+	ret = getrandom(buf, len, 0);
+
+	if(ret < 0) {
+		lua_pushstring(L, strerror(errno));
+		return lua_error(L);
+	}
+
+#elif defined(WITH_ARC4RANDOM)
+	arc4random_buf(buf, len);
+	ret = len;
+#elif defined(WITH_OPENSSL)
+	if(!RAND_status()) {
+		lua_pushliteral(L, "OpenSSL PRNG not seeded");
+		return lua_error(L);
+	}
+
+	ret = RAND_bytes(buf, len);
+
+	if(ret == 1) {
+		ret = len;
+	} else {
+		/* TODO ERR_get_error() */
+		lua_pushstring(L, "RAND_bytes() failed");
+		return lua_error(L);
+	}
+
+#endif
+
+	lua_pushlstring(L, buf, ret);
+	return 1;
+}
+
+int luaopen_util_crand(lua_State *L) {
+#if (LUA_VERSION_NUM > 501)
+	luaL_checkversion(L);
+#endif
+
+	lua_newtable(L);
+	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;
+}
+