From 5d386c0613024993566fb3bef13a1e33fa93e91c Mon Sep 17 00:00:00 2001
From: Alin Serdean <aserdean at cloudbasesolutions.com>
Date: Thu, 19 Dec 2013 09:20:17 -0800
Subject: [PATCH] entropy: Add Windows support.

Signed-off-by: Alin Serdean <aserdean at cloudbasesolutions.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
---
 lib/entropy.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/lib/entropy.c b/lib/entropy.c
index 02f56e0f4..fd7356652 100644
--- a/lib/entropy.c
+++ b/lib/entropy.c
@@ -20,6 +20,9 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <unistd.h>
+#ifdef _WIN32
+#include <Wincrypt.h>
+#endif
 
 #include "socket-util.h"
 #include "vlog.h"
@@ -33,6 +36,7 @@ static const char urandom[] = "/dev/urandom";
 int
 get_entropy(void *buffer, size_t n)
 {
+#ifndef _WIN32
     size_t bytes_read;
     int error;
     int fd;
@@ -49,6 +53,31 @@ get_entropy(void *buffer, size_t n)
     if (error) {
         VLOG_ERR("%s: read error (%s)", urandom, ovs_retval_to_string(error));
     }
+#else
+    int error = 0;
+    HCRYPTPROV   crypt_prov = 0;
+    LPVOID msg_buf;
+
+    CryptAcquireContext(&crypt_prov, NULL, NULL,
+                        PROV_RSA_FULL, CRYPT_VERIFYCONTEXT);
+    if (!CryptGenRandom(crypt_prov, n, buffer)) {
+        error = EINVAL;
+        FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER
+                      | FORMAT_MESSAGE_FROM_SYSTEM
+                      | FORMAT_MESSAGE_IGNORE_INSERTS,
+                      NULL,
+                      GetLastError(),
+                      0,
+                      (LPTSTR)&msg_buf,
+                      0,
+                      NULL
+            );
+        VLOG_ERR("CryptGenRandom: read error (%s)", msg_buf);
+        LocalFree(msg_buf);
+    }
+
+    CryptReleaseContext(crypt_prov, 0);
+#endif
     return error;
 }
 
-- 
2.20.1