From 1202631fa64aa5c85f9250cceb2515ea3870ac84 Mon Sep 17 00:00:00 2001
From: joe-conigliaro <joe-conigliaro@users.noreply.github.com>
Date: Wed, 31 Jul 2019 11:24:12 +1000
Subject: [PATCH] crypto.rand module

---
 vlib/crypto/rand/rand.v      | 21 +++++++++++++++
 vlib/crypto/rand/rand_lin.v  | 51 ++++++++++++++++++++++++++++++++++++
 vlib/crypto/rand/rand_mac.v  | 26 ++++++++++++++++++
 vlib/crypto/rand/rand_test.v | 13 +++++++++
 vlib/crypto/rand/rand_win.v  | 23 ++++++++++++++++
 5 files changed, 134 insertions(+)
 create mode 100644 vlib/crypto/rand/rand.v
 create mode 100644 vlib/crypto/rand/rand_lin.v
 create mode 100644 vlib/crypto/rand/rand_mac.v
 create mode 100644 vlib/crypto/rand/rand_test.v
 create mode 100644 vlib/crypto/rand/rand_win.v

diff --git a/vlib/crypto/rand/rand.v b/vlib/crypto/rand/rand.v
new file mode 100644
index 0000000000..8b412d2f60
--- /dev/null
+++ b/vlib/crypto/rand/rand.v
@@ -0,0 +1,21 @@
+// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+
+module rand
+
+const (
+	ReadError = error('crypro.rand.read() error reading random bytes.')
+)
+
+// NOTE: temp until we have []bytes(buff)
+fn c_array_to_bytes_tmp(len, buffer voidptr) []byte {
+	mut arr := []byte
+	arr = array {
+		len: len
+		cap: 1
+		element_size: 1
+		data: buffer
+	}
+	return arr
+}
diff --git a/vlib/crypto/rand/rand_lin.v b/vlib/crypto/rand/rand_lin.v
new file mode 100644
index 0000000000..c5d3df6c2f
--- /dev/null
+++ b/vlib/crypto/rand/rand_lin.v
@@ -0,0 +1,51 @@
+// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+
+module rand
+
+import math
+
+#include <sys/syscall.h>
+
+import const(
+	SYS_getrandom
+)
+
+// const (
+// 	SYS_getrandom = 278 // AArch65
+// 	SYS_getrandom = 384 // ARM
+// 	SYS_getrandom = 355 // x86
+// 	SYS_getrandom = 318 // x86_64
+// )
+
+const (
+	ReadBatchSize = 256
+)
+
+pub fn read(bytes_needed int) ?[]byte {	
+	mut buffer := malloc(bytes_needed)
+	mut bytes_read := 0
+	// getrandom syscall wont block if requesting <= 256 bytes
+	if bytes_needed > ReadBatchSize {
+		no_batches := int(math.floor(f64(bytes_needed/ReadBatchSize)))
+		for i:=0; i<no_batches; i++ {
+			if _getrandom(ReadBatchSize, buffer+bytes_read) == -1 {
+				return ReadError
+			}
+			bytes_read += ReadBatchSize
+		}
+	}
+	if _getrandom(bytes_needed-bytes_read, buffer+bytes_read) == -1 {
+		return ReadError
+	}
+	
+	return c_array_to_bytes_tmp(bytes_needed, buffer)
+}
+
+fn _getrandom(bytes_needed int, buffer voidptr) int {
+	if bytes_needed > ReadBatchSize {
+		panic('_getrandom() dont request more thane $ReadBatchSize bytes at once.')
+	}
+	return C.syscall(SYS_getrandom, buffer, bytes_needed, 0)
+}
diff --git a/vlib/crypto/rand/rand_mac.v b/vlib/crypto/rand/rand_mac.v
new file mode 100644
index 0000000000..085de05345
--- /dev/null
+++ b/vlib/crypto/rand/rand_mac.v
@@ -0,0 +1,26 @@
+// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+
+module rand
+
+#flag darwin -framework Security
+
+// import const (
+// 	kSecRandomDefault
+// 	errSecSuccess
+// )
+
+const (
+	kSecRandomDefault = 0
+	errSecSuccess     = 0
+)
+
+pub fn read(bytes_needed int) ?[]byte {
+	mut buffer := malloc(bytes_needed)
+	status := C.SecRandomCopyBytes(kSecRandomDefault, bytes_needed, buffer)
+	if status != errSecSuccess {
+		return ReadError
+	}
+	return c_array_to_bytes_tmp(bytes_needed, buffer)
+}
diff --git a/vlib/crypto/rand/rand_test.v b/vlib/crypto/rand/rand_test.v
new file mode 100644
index 0000000000..7d0bc0c97b
--- /dev/null
+++ b/vlib/crypto/rand/rand_test.v
@@ -0,0 +1,13 @@
+// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+
+import crypto.rand
+
+fn test_crypto_rand() {
+	r := rand.read(100) or {
+		assert false
+		return
+	}
+	assert r.len == 100
+}
diff --git a/vlib/crypto/rand/rand_win.v b/vlib/crypto/rand/rand_win.v
new file mode 100644
index 0000000000..200b98ffb7
--- /dev/null
+++ b/vlib/crypto/rand/rand_win.v
@@ -0,0 +1,23 @@
+// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+
+module rand
+
+#flag windows -Llibraries/bcrypt -lbcrypt
+#include <bcrypt.h>
+
+const (
+	STATUS_SUCCESS                  = 0x00000000
+	BCRYPT_USE_SYSTEM_PREFERRED_RNG = 0x00000002
+)
+
+pub fn read(bytes_needed int) ?[]byte {	
+	mut buffer := malloc(bytes_needed)
+	// use BCRYPT_USE_SYSTEM_PREFERRED_RNG because we passed null as algo
+	status := C.BCryptGenRandom(0, buffer, bytes_needed, BCRYPT_USE_SYSTEM_PREFERRED_RNG)
+	if status != STATUS_SUCCESS {
+		return ReadError
+	}
+	return c_array_to_bytes_tmp(bytes_needed, buffer)
+}