From 3d04344cc9c8e94ad5502015b8c4b0b269ac78c2 Mon Sep 17 00:00:00 2001
From: Lu Wang <luwannest@users.noreply.github.com>
Date: Fri, 26 Aug 2016 14:41:40 +0800
Subject: [PATCH] Enhance otPlatRandomGet API to provide random stream (#471)

* Enhance otPlatRandomGet API to provide random stream
---
 examples/platforms/cc2538/random.c | 20 ++++++++++++++++++++
 examples/platforms/posix/random.c  | 20 ++++++++++++++++++++
 include/platform/random.h          | 15 +++++++++++++++
 3 files changed, 55 insertions(+)

diff --git a/examples/platforms/cc2538/random.c b/examples/platforms/cc2538/random.c
index 88f4df97f..30dd8223a 100644
--- a/examples/platforms/cc2538/random.c
+++ b/examples/platforms/cc2538/random.c
@@ -34,6 +34,9 @@
  *   This implementation is not a true random number generator and does @em satisfy the Thread requirements.
  */
 
+#include <openthread-types.h>
+
+#include <common/code_utils.hpp>
 #include <platform/random.h>
 #include "platform-cc2538.h"
 
@@ -66,3 +69,20 @@ uint32_t otPlatRandomGet(void)
 
     return mlcg;
 }
+
+ThreadError otPlatSecureRandomGet(uint16_t aInputLength, uint8_t *aOutput, uint16_t *aOutputLength)
+{
+    ThreadError error = kThreadError_None;
+
+    VerifyOrExit(aOutput && aOutputLength, error = kThreadError_InvalidArgs);
+
+    for (uint16_t length = 0; length < aInputLength; length++)
+    {
+        aOutput[length] = (uint8_t)otPlatRandomGet();
+    }
+
+    *aOutputLength = aInputLength;
+
+exit:
+    return error;
+}
diff --git a/examples/platforms/posix/random.c b/examples/platforms/posix/random.c
index a7eb9f0be..fd1984418 100644
--- a/examples/platforms/posix/random.c
+++ b/examples/platforms/posix/random.c
@@ -34,6 +34,9 @@
  *   This implementation is not a true random number generator and does @em satisfy the Thread requirements.
  */
 
+#include <openthread-types.h>
+
+#include <common/code_utils.hpp>
 #include <platform/random.h>
 #include "platform-posix.h"
 
@@ -65,3 +68,20 @@ uint32_t otPlatRandomGet(void)
 
     return mlcg;
 }
+
+ThreadError otPlatSecureRandomGet(uint16_t aInputLength, uint8_t *aOutput, uint16_t *aOutputLength)
+{
+    ThreadError error = kThreadError_None;
+
+    VerifyOrExit(aOutput && aOutputLength, error = kThreadError_InvalidArgs);
+
+    for (uint16_t length = 0; length < aInputLength; length++)
+    {
+        aOutput[length] = (uint8_t)otPlatRandomGet();
+    }
+
+    *aOutputLength = aInputLength;
+
+exit:
+    return error;
+}
diff --git a/include/platform/random.h b/include/platform/random.h
index 656a51335..c5e629b82 100644
--- a/include/platform/random.h
+++ b/include/platform/random.h
@@ -52,6 +52,21 @@ extern "C" {
  *
  */
 
+/**
+ * Get random stream.
+ *
+ * @param[in]   aInputLength      The expected size of random values.
+ * @param[out]  aOutput           A pointer to the buffer for the generated random stream. The pointer should never be NULL.
+ * @param[out]  aOutputLength     A pointer to the generated size of random stream.
+ *                                It is supposed to be the same as aInputLength, but maybe less than aInputLength.
+ *                                The pointer should never be NULL.
+ *
+ * @retval kThreadError_None         Generate random successfully.
+ * @retval kThreadError_Fail         Generate random fail.
+ * @retval kThreadError_InvalidArgs  Invalid args.
+ */
+ThreadError otPlatSecureRandomGet(uint16_t aInputLength, uint8_t *aOutput, uint16_t *aOutputLength);
+
 /**
  * Get a 32-bit true random value.
  *