From bf3678ca81204f8ea9c253cc35a96c6c7ce12b42 Mon Sep 17 00:00:00 2001
From: Peter Dettman <peter.dettman@bouncycastle.org>
Date: Sat, 8 Oct 2022 20:06:43 +0700
Subject: New Spans methods

---
 crypto/src/crypto/io/CipherStream.cs         |  2 +-
 crypto/src/crypto/modes/KCcmBlockCipher.cs   |  2 +-
 crypto/src/tls/ByteQueue.cs                  |  4 +++-
 crypto/src/tls/crypto/impl/bc/BcTlsCrypto.cs |  2 +-
 crypto/src/util/Spans.cs                     | 24 ++++++++++++++++++++++++
 5 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/crypto/src/crypto/io/CipherStream.cs b/crypto/src/crypto/io/CipherStream.cs
index 145fa7fd3..6802e81d7 100644
--- a/crypto/src/crypto/io/CipherStream.cs
+++ b/crypto/src/crypto/io/CipherStream.cs
@@ -219,7 +219,7 @@ namespace Org.BouncyCastle.Crypto.IO
             byte[] output = outputSize > 0 ? ArrayPool<byte>.Shared.Rent(outputSize) : null;
             try
             {
-                int length = m_writeCipher.ProcessBytes(buffer, Spans.FromNullable(output, 0));
+                int length = m_writeCipher.ProcessBytes(buffer, Spans.FromNullable(output));
                 if (length > 0)
                 {
                     m_stream.Write(output[..length]);
diff --git a/crypto/src/crypto/modes/KCcmBlockCipher.cs b/crypto/src/crypto/modes/KCcmBlockCipher.cs
index cc4a5060c..5fb8d77c6 100644
--- a/crypto/src/crypto/modes/KCcmBlockCipher.cs
+++ b/crypto/src/crypto/modes/KCcmBlockCipher.cs
@@ -463,7 +463,7 @@ namespace Org.BouncyCastle.Crypto.Modes
                     ? stackalloc byte[macSize]
                     : new byte[macSize];
 
-                buffer.AsSpan(0, macSize).CopyTo(calculatedMac);
+                calculatedMac.CopyFrom(buffer);
 
                 if (!Arrays.ConstantTimeAreEqual(mac.AsSpan(0, macSize), calculatedMac))
                     throw new InvalidCipherTextException("mac check failed");
diff --git a/crypto/src/tls/ByteQueue.cs b/crypto/src/tls/ByteQueue.cs
index b85106528..74a7104ba 100644
--- a/crypto/src/tls/ByteQueue.cs
+++ b/crypto/src/tls/ByteQueue.cs
@@ -1,6 +1,8 @@
 using System;
 using System.IO;
 
+using Org.BouncyCastle.Utilities;
+
 namespace Org.BouncyCastle.Tls
 {
     /// <summary>A queue for bytes. This file could be more optimized.</summary>
@@ -171,7 +173,7 @@ namespace Org.BouncyCastle.Tls
             if ((m_available - skip) < buffer.Length)
                 throw new InvalidOperationException("Not enough data to read");
 
-            m_databuf.AsSpan(m_skipped + skip, buffer.Length).CopyTo(buffer);
+            buffer.CopyFrom(m_databuf.AsSpan(m_skipped + skip));
         }
 #endif
 
diff --git a/crypto/src/tls/crypto/impl/bc/BcTlsCrypto.cs b/crypto/src/tls/crypto/impl/bc/BcTlsCrypto.cs
index 79c994fc0..a4964c4b3 100644
--- a/crypto/src/tls/crypto/impl/bc/BcTlsCrypto.cs
+++ b/crypto/src/tls/crypto/impl/bc/BcTlsCrypto.cs
@@ -149,7 +149,7 @@ namespace Org.BouncyCastle.Tls.Crypto.Impl.BC
         public override TlsNonceGenerator CreateNonceGenerator(byte[] additionalSeedMaterial)
         {
 #if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
-            return CreateNonceGenerator(Spans.FromNullable(additionalSeedMaterial, 0));
+            return CreateNonceGenerator(Spans.FromNullableReadOnly(additionalSeedMaterial));
 #else
             int cryptoHashAlgorithm = CryptoHashAlgorithm.sha256;
             IDigest digest = CreateDigest(cryptoHashAlgorithm);
diff --git a/crypto/src/util/Spans.cs b/crypto/src/util/Spans.cs
index 5e1b3737c..fa2b768d9 100644
--- a/crypto/src/util/Spans.cs
+++ b/crypto/src/util/Spans.cs
@@ -8,11 +8,35 @@ namespace Org.BouncyCastle.Utilities
 {
     internal static class Spans
     {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        internal static void CopyFrom<T>(this Span<T> output, ReadOnlySpan<T> input)
+        {
+            input[..output.Length].CopyTo(output);
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        internal static Span<T> FromNullable<T>(T[]? array)
+        {
+            return array == null ? Span<T>.Empty : array.AsSpan();
+        }
+
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         internal static Span<T> FromNullable<T>(T[]? array, int start)
         {
             return array == null ? Span<T>.Empty : array.AsSpan(start);
         }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        internal static ReadOnlySpan<T> FromNullableReadOnly<T>(T[]? array)
+        {
+            return array == null ? Span<T>.Empty : array.AsSpan();
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        internal static ReadOnlySpan<T> FromNullableReadOnly<T>(T[]? array, int start)
+        {
+            return array == null ? Span<T>.Empty : array.AsSpan(start);
+        }
     }
 }
 #endif
-- 
cgit 1.4.1