From 5e32450ccf9186e86a7596a7d774621cf81c62ff Mon Sep 17 00:00:00 2001
From: vnugent <public@vaughnnugent.com>
Date: Mon, 10 Jun 2024 22:08:52 -0400
Subject: feat: Begin migrating noscrypt c# library

---
 .../src/UnmanagedRandomSource.cs                   | 104 +++++++++++++++++++++
 1 file changed, 104 insertions(+)
 create mode 100644 wrappers/dotnet/VNLib.Utils.Cryptography.Noscrypt/src/UnmanagedRandomSource.cs

(limited to 'wrappers/dotnet/VNLib.Utils.Cryptography.Noscrypt/src/UnmanagedRandomSource.cs')

diff --git a/wrappers/dotnet/VNLib.Utils.Cryptography.Noscrypt/src/UnmanagedRandomSource.cs b/wrappers/dotnet/VNLib.Utils.Cryptography.Noscrypt/src/UnmanagedRandomSource.cs
new file mode 100644
index 0000000..91ff64b
--- /dev/null
+++ b/wrappers/dotnet/VNLib.Utils.Cryptography.Noscrypt/src/UnmanagedRandomSource.cs
@@ -0,0 +1,104 @@
+// Copyright (C) 2024 Vaughn Nugent
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+using System;
+using System.Runtime.InteropServices;
+
+using VNLib.Utils;
+using VNLib.Utils.Native;
+using VNLib.Utils.Extensions;
+
+namespace VNLib.Utils.Cryptography.Noscrypt
+{
+
+    /// <summary>
+    /// A wrapper class for an unmanaged random source that conforms to the <see cref="IRandomSource"/> interface
+    /// </summary>
+    public class UnmanagedRandomSource : VnDisposeable, IRandomSource
+    {
+        /// <summary>
+        /// The explicit name of the unmanaged random function to get random bytes
+        /// </summary>
+        public const string RngFunctionName = "GetRandomBytes";
+
+        unsafe delegate void UnmanagedRandomSourceDelegate(byte* buffer, int size);
+
+        private readonly bool OwnsHandle;
+        private readonly SafeLibraryHandle _library;
+        private readonly UnmanagedRandomSourceDelegate _getRandomBytes;
+
+        /// <summary>
+        /// Loads the unmanaged random source from the given library 
+        /// and attempts to get the random bytes method <see cref="RngFunctionName"/>
+        /// </summary>
+        /// <param name="path"></param>
+        /// <param name="search"></param>
+        /// <returns>The wrapped library that conforms to the <see cref="IRandomSource"/></returns>
+        public static UnmanagedRandomSource LoadLibrary(string path, DllImportSearchPath search)
+        {
+            //Try to load the library
+            SafeLibraryHandle lib = SafeLibraryHandle.LoadLibrary(path, search);
+            try
+            {
+                return new UnmanagedRandomSource(lib, true);
+            }
+            catch
+            {
+                //release lib
+                lib.Dispose();
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// Creates the unmanaged random source from the given library
+        /// </summary>
+        /// <param name="lib">The library handle to wrap</param>
+        /// <exception cref="ObjectDisposedException"></exception>
+        /// <exception cref="EntryPointNotFoundException"></exception>
+        public UnmanagedRandomSource(SafeLibraryHandle lib, bool ownsHandle)
+        {
+            lib.ThrowIfClosed();
+
+            _library = lib;
+
+            //get the method delegate
+            _getRandomBytes = lib.DangerousGetFunction<UnmanagedRandomSourceDelegate>(RngFunctionName);
+
+            OwnsHandle = ownsHandle;
+        }
+
+        ///<inheritdoc/>
+        public unsafe void GetRandomBytes(Span<byte> buffer)
+        {
+            _library.ThrowIfClosed();
+
+            //Fix buffer and call unmanaged method
+            fixed (byte* ptr = &MemoryMarshal.GetReference(buffer))
+            {
+                _getRandomBytes(ptr, buffer.Length);
+            }
+        }
+
+        ///<inheritdoc/>
+        protected override void Free()
+        {
+            if (OwnsHandle)
+            {
+                _library.Dispose();
+            }
+        }
+    }
+}
\ No newline at end of file
-- 
cgit