Progress on tutorial, gap tweaking (water flows faster from room to room), UPnP error messages, input keys in array, underwater aiming tweaking, tons of misc stuff commit more often ffs

Lidgren.Network/Encryption/NetBlockEncryptionBase.cs

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+using System;
+using System.Collections.Generic;
+
+namespace Lidgren.Network
+{
+	/// <summary>
+	/// Base for a non-threadsafe encryption class
+	/// </summary>
+	public abstract class NetBlockEncryptionBase : INetEncryption
+	{
+		// temporary space for one block to avoid reallocating every time
+		private byte[] m_tmp;
+
+		/// <summary>
+		/// Block size in bytes for this cipher
+		/// </summary>
+		public abstract int BlockSize { get; }
+
+		/// <summary>
+		/// NetBlockEncryptionBase constructor
+		/// </summary>
+		public NetBlockEncryptionBase()
+		{
+			m_tmp = new byte[BlockSize];
+		}
+
+		/// <summary>
+		/// Encrypt am outgoing message with this algorithm; no writing can be done to the message after encryption, or message will be corrupted
+		/// </summary>
+		public bool Encrypt(NetOutgoingMessage msg)
+		{
+			int payloadBitLength = msg.LengthBits;
+			int numBytes = msg.LengthBytes;
+			int blockSize = BlockSize;
+			int numBlocks = (int)Math.Ceiling((double)numBytes / (double)blockSize);
+			int dstSize = numBlocks * blockSize;
+
+			msg.EnsureBufferSize(dstSize * 8 + (4 * 8)); // add 4 bytes for payload length at end
+			msg.LengthBits = dstSize * 8; // length will automatically adjust +4 bytes when payload length is written
+
+			for(int i=0;i<numBlocks;i++)
+			{
+				EncryptBlock(msg.m_data, (i * blockSize), m_tmp);
+				Buffer.BlockCopy(m_tmp, 0, msg.m_data, (i * blockSize), m_tmp.Length);
+			}
+
+			// add true payload length last
+			msg.Write((UInt32)payloadBitLength);
+
+			return true;
+		}
+
+		/// <summary>
+		/// Decrypt an incoming message encrypted with corresponding Encrypt
+		/// </summary>
+		/// <param name="msg">message to decrypt</param>
+		/// <returns>true if successful; false if failed</returns>
+		public bool Decrypt(NetIncomingMessage msg)
+		{
+			int numEncryptedBytes = msg.LengthBytes - 4; // last 4 bytes is true bit length
+			int blockSize = BlockSize;
+			int numBlocks = numEncryptedBytes / blockSize;
+			if (numBlocks * blockSize != numEncryptedBytes)
+				return false;
+
+			for (int i = 0; i < numBlocks; i++)
+			{
+				DecryptBlock(msg.m_data, (i * blockSize), m_tmp);
+				Buffer.BlockCopy(m_tmp, 0, msg.m_data, (i * blockSize), m_tmp.Length);
+			}
+
+			// read 32 bits of true payload length
+			uint realSize = NetBitWriter.ReadUInt32(msg.m_data, 32, (numEncryptedBytes * 8));
+			msg.m_bitLength = (int)realSize;
+			return true;
+		}
+
+		/// <summary>
+		/// Encrypt a block of bytes
+		/// </summary>
+		protected abstract void EncryptBlock(byte[] source, int sourceOffset, byte[] destination);
+
+		/// <summary>
+		/// Decrypt a block of bytes
+		/// </summary>
+		protected abstract void DecryptBlock(byte[] source, int sourceOffset, byte[] destination);
+	}
+}