Added implementation of Modbus TCP Server

AMWD.Protocols.Modbus.Common/InternalsVisibleTo.cs

@@ -1,3 +1,4 @@
 using System.Runtime.CompilerServices;
 
 [assembly: InternalsVisibleTo("AMWD.Protocols.Modbus.Tests")]
+[assembly: InternalsVisibleTo("DynamicProxyGenAssembly2")]

AMWD.Protocols.Modbus.Common/Protocols/TcpProtocol.cs

@@ -59,6 +59,15 @@ namespace AMWD.Protocols.Modbus.Common.Protocols
 		/// </summary>
 		public const ushort MAX_REGISTER_WRITE_COUNT = 0x007B; // 123
 
+		/// <summary>
+		/// The maximum allowed ADU length in bytes.
+		/// </summary>
+		/// <remarks>
+		/// A Modbus frame consists of a PDU (protcol data unit) and additional protocol addressing / error checks.
+		/// The whole data frame is called ADU (application data unit).
+		/// </remarks>
+		public const int MAX_ADU_LENGTH = 260; // bytes
+
 		#endregion Constants
 
 		/// <inheritdoc/>

AMWD.Protocols.Modbus.Tcp/AMWD.Protocols.Modbus.Tcp.csproj

@@ -13,6 +13,12 @@
     <PackageTags>Modbus Protocol Network TCP LAN</PackageTags>
   </PropertyGroup>
 
+  <ItemGroup>
+    <Compile Include="../AMWD.Protocols.Modbus.Common/InternalsVisibleTo.cs" Link="InternalsVisibleTo.cs" />
+    <Compile Include="../AMWD.Protocols.Modbus.Common/Extensions/ArrayExtensions.cs" Link="Extensions/ArrayExtensions.cs" />
+    <Compile Include="../AMWD.Protocols.Modbus.Common/Extensions/ReaderWriterLockSlimExtensions.cs" Link="Extensions/ReaderWriterLockSlimExtensions.cs" />
+  </ItemGroup>
+
   <ItemGroup>
     <None Include="README.md" Pack="true" PackagePath="/" />
   </ItemGroup>

AMWD.Protocols.Modbus.Tcp/Events/CoilWrittenEventArgs.cs

@@ -0,0 +1,25 @@
+using System;
+
+namespace AMWD.Protocols.Modbus.Tcp.Events
+{
+	/// <summary>
+	/// Represents the coil written event arguments.
+	/// </summary>
+	public class CoilWrittenEventArgs : EventArgs
+	{
+		/// <summary>
+		/// Gets or sets the unit id.
+		/// </summary>
+		public byte UnitId { get; internal set; }
+
+		/// <summary>
+		/// Gets or sets the coil address.
+		/// </summary>
+		public ushort Address { get; internal set; }
+
+		/// <summary>
+		/// Gets or sets the coil value.
+		/// </summary>
+		public bool Value { get; internal set; }
+	}
+}

AMWD.Protocols.Modbus.Tcp/Events/RegisterWrittenEventArgs.cs

@@ -0,0 +1,35 @@
+using System;
+
+namespace AMWD.Protocols.Modbus.Tcp.Events
+{
+	/// <summary>
+	/// Represents the register written event arguments.
+	/// </summary>
+	public class RegisterWrittenEventArgs : EventArgs
+	{
+		/// <summary>
+		/// Gets or sets the unit id.
+		/// </summary>
+		public byte UnitId { get; internal set; }
+
+		/// <summary>
+		/// Gets or sets the address of the register.
+		/// </summary>
+		public ushort Address { get; internal set; }
+
+		/// <summary>
+		/// Gets or sets the value of the register.
+		/// </summary>
+		public ushort Value { get; internal set; }
+
+		/// <summary>
+		/// Gets or sets the high byte of the register.
+		/// </summary>
+		public byte HighByte { get; internal set; }
+
+		/// <summary>
+		/// Gets or sets the low byte of the register.
+		/// </summary>
+		public byte LowByte { get; internal set; }
+	}
+}

AMWD.Protocols.Modbus.Tcp/Extensions/StreamExtensions.cs

@@ -0,0 +1,26 @@
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace System.IO
+{
+	internal static class StreamExtensions
+	{
+		public static async Task<byte[]> ReadExpectedBytesAsync(this Stream stream, int expectedBytes, CancellationToken cancellationToken = default)
+		{
+			byte[] buffer = new byte[expectedBytes];
+			int offset = 0;
+			do
+			{
+				int count = await stream.ReadAsync(buffer, offset, expectedBytes - offset, cancellationToken).ConfigureAwait(false);
+				if (count < 1)
+					throw new EndOfStreamException();
+
+				offset += count;
+			}
+			while (offset < expectedBytes && !cancellationToken.IsCancellationRequested);
+
+			cancellationToken.ThrowIfCancellationRequested();
+			return buffer;
+		}
+	}
+}

AMWD.Protocols.Modbus.Tcp/InternalsVisibleTo.cs

@@ -1,4 +0,0 @@
-using System.Runtime.CompilerServices;
-
-[assembly: InternalsVisibleTo("AMWD.Protocols.Modbus.Tests")]
-[assembly: InternalsVisibleTo("DynamicProxyGenAssembly2")]

AMWD.Protocols.Modbus.Tests/Tcp/Utils/ModbusTcpConnectionTest.cs

@@ -161,8 +161,8 @@ namespace AMWD.Protocols.Modbus.Tests.Tcp.Utils
 		public async Task ShouldThrowApplicationExceptionHostnameNotResolvable()
 		{
 			// Arrange
-			_hostname = "123.321.123.321";
 			var connection = GetConnection();
+			connection.GetType().GetField("_hostname", BindingFlags.NonPublic | BindingFlags.Instance).SetValue(connection, "");
 
 			// Act
 			await connection.ConnectAsync();