pooled buffers for hmac signing and a test

Author: stevenaw

sdk/src/Core/AWSSDK.Core.NetStandard.csproj

@@ -74,5 +74,6 @@
 
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <PackageReference Include="Microsoft.Bcl.AsyncInterfaces" Version="1.1.0" />
+    <PackageReference Include="System.Buffers" Version="4.3.0" />
   </ItemGroup>
 </Project>

sdk/src/Core/Amazon.Util/CryptoUtil.cs

@@ -16,6 +16,8 @@
 using Amazon.Runtime.Internal.Util;
 using Amazon.Util.Internal;
 using AWSSDK.Runtime.Internal.Util;
+using System;
+using System.Buffers;
 using System.IO;
 using System.Security.Cryptography;
 using System.Text;
@@ -98,8 +100,21 @@ internal CryptoUtil()
             /// <returns>Computed hash code</returns>
             public string HMACSign(string data, string key, SigningAlgorithm algorithmName)
             {
-                var binaryData = Encoding.UTF8.GetBytes(data);
-                return HMACSign(binaryData, key, algorithmName);
+                Encoding encoding = Encoding.UTF8;
+                int maxSize = encoding.GetMaxByteCount(data.Length);
+                byte[] buffer = ArrayPool<byte>.Shared.Rent(maxSize);
+
+                try
+                {
+                    int size = encoding.GetBytes(data, buffer);
+                    ArraySegment<byte> segment = new ArraySegment<byte>(buffer, 0, size);
+
+                    return HMACSign(segment, key, algorithmName);
+                }
+                finally
+                {
+                    ArrayPool<byte>.Shared.Return(buffer);
+                }
             }
 
             /// <summary>

sdk/src/Core/Amazon.Util/_netstandard/CryptoUtil.netstandard.cs

@@ -30,11 +30,14 @@ public static partial class CryptoUtilFactory
         partial class CryptoUtil : ICryptoUtil
         {
             public string HMACSign(byte[] data, string key, SigningAlgorithm algorithmName)
+                => HMACSign(new ArraySegment<byte>(data, 0, data.Length), key, algorithmName);
+
+            private string HMACSign(ArraySegment<byte> data, string key, SigningAlgorithm algorithmName)
             {
                 if (String.IsNullOrEmpty(key))
                     throw new ArgumentNullException("key", "Please specify a Secret Signing Key.");
 
-                if (data == null || data.Length == 0)
+                if (data == null || data.Count == 0)
                     throw new ArgumentNullException("data", "Please specify data to sign.");
 
                 KeyedHashAlgorithm algorithm = CreateKeyedHashAlgorithm(algorithmName);
@@ -44,7 +47,7 @@ public string HMACSign(byte[] data, string key, SigningAlgorithm algorithmName)
                 try
                 {
                     algorithm.Key = Encoding.UTF8.GetBytes(key);
-                    byte[] bytes = algorithm.ComputeHash(data);
+                    byte[] bytes = algorithm.ComputeHash(data.Array, data.Offset, data.Count);
                     return Convert.ToBase64String(bytes);
                 }
                 finally

sdk/src/Core/Amazon.Util/_netstandard/Extensions.cs

@@ -1,8 +1,6 @@
 using System;
-using System.Collections.Generic;
 using System.Globalization;
-using System.Linq;
-using System.Threading.Tasks;
+using System.Text;
 
 namespace Amazon.Util
 {
@@ -14,5 +12,10 @@ internal static string ToUpper(this String str, CultureInfo culture)
                 throw new ArgumentException("The extension method ToUpper only works for invariant culture");
             return str.ToUpperInvariant();
         }
+
+#if !NETCOREAPP3_1_OR_GREATER
+        internal static int GetBytes(this Encoding encoding, string chars, byte[] bytes)
+            => encoding.GetBytes(chars, 0, chars.Length, bytes, 0);
+#endif
     }
 }

sdk/test/NetStandard/UnitTests/Core/CryptoUtilTests.cs

@@ -0,0 +1,18 @@
+using Amazon.Runtime;
+using Amazon.Util;
+using Xunit;
+
+namespace UnitTests.NetStandard.Core
+{
+    public class CryptoUtilTests
+    {
+        [Fact]
+        [Trait("Category", "Core")]
+        public void HMACSignFromString()
+        {
+            var actual = CryptoUtilFactory.CryptoInstance.HMACSign("HELLOWORLD", "HELLOKEY", SigningAlgorithm.HmacSHA256);
+
+            Assert.Equal("LH+6qR+N6WU91evFKfjq/6NqiVES5BD6z6EHYsDwOUE=", actual);
+        }
+    }
+}