MultiClientTCPServerSocket Class

Imports System.Net.Sockets
Imports System.Net
Namespace MultiClientTCPServerSocket

    'Author:    LaPanthere
    'Date:      4th of June, 2013
    'Desc:      A simple class with event calling that will run multiple clients. Store the clients in a list of sockets if you wish to do stuff with them.
    'Credits:   None, based off my own work with async sockets.

    Public Class MultiClientTCPSeverSocket
        Public Event MessageReceived As MessageReceivedEventHandler
        Public Event ClientConnected As ClientConnectedEventHandler
        Public Event ClientDisconnected As ClientDisconnectedEventHandler
        Dim clientSocket As Socket
        Dim serverSocket As Socket
        Dim port As String
        Dim byteSize(66291456) As Byte
        Dim IpEndPoint As Net.IPEndPoint

        Public Delegate Sub MessageReceivedEventHandler(ByVal sender As Object, ByVal e As MessageReceivedEventArgs)
        Public Delegate Sub ClientConnectedEventHandler(ByVal sender As Object, ByVal e As ClientConnectedEventArgs)
        Public Delegate Sub ClientDisconnectedEventHandler(ByVal sender As Object, ByVal e As ClientDisconnectedEventArgs)

        ''' <summary>
        ''' Creates a new Multiple client server socket
        ''' </summary>
        ''' <param name="port">The port to listen for clients</param>
        ''' <param name="buffer">The buffer for messages</param>
        ''' <remarks></remarks>
        Public Sub New(ByVal port As String, Optional ByVal buffer() As Byte = Nothing)
            'General defining of existing strings/related
            Me.port = port
            If Not IsNothing(buffer) Then
                Me.byteSize = buffer
            End If
        End Sub

        ''' <summary>
        ''' Starts the server with the specified data (define a new instance to use this method)
        ''' </summary>
        ''' <returns></returns>
        ''' <remarks></remarks>
        Public Function StartServer() As Boolean
            Try
                'Define what the server socket really is
                serverSocket = New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)

                'Create a local IP endpoint
                IpEndPoint = New Net.IPEndPoint(IPAddress.Any, Me.port)

                'Create the local endpoint ip bind
                serverSocket.Bind(IpEndPoint)

                'Allow several thousand clients to be backlogged
                serverSocket.Listen(500000)

                'Start accepting clients through the socket
                serverSocket.BeginAccept(New AsyncCallback(AddressOf OnClientAccept), Nothing)
                Return True
            Catch
                Return False
            End Try
        End Function

        ''' <summary>
        ''' Attempts to close the server socket and end all connecting clients
        ''' </summary>
        ''' <param name="timeout">The time before closing the socket</param>
        ''' <returns></returns>
        ''' <remarks></remarks>
        Public Function CloseServer(Optional ByVal timeout As Integer = 1) As Boolean
            Try
                serverSocket.Close(timeout)
                Return True
            Catch
                Return False
            End Try
        End Function
        Public Function DisconnectClient(ByVal client As Socket) As Boolean
            Try
                'Begin disconnecting a client and assign its async call back to OnClientDisconnect
                client.BeginDisconnect(False, New AsyncCallback(AddressOf OnClientDisconnect), client)
                Return True
            Catch
                Return False
            End Try
        End Function


        ''' <summary>
        ''' Sends a message asynchronously to the client socket specified
        ''' </summary>
        ''' <param name="message">The message you wish to send</param>
        ''' <param name="client">The socket that you wish to send the message to, can be grabbed from most events</param>
        ''' <returns></returns>
        ''' <remarks></remarks>
        Public Function SendMessage(ByVal message As String, ByVal client As Socket) As Boolean
            Try
                'Define bytes to send by getting the bytes from the message string
                Dim sendBytes As Byte() = System.Text.ASCIIEncoding.ASCII.GetBytes(message)

                'Begin sending data and assign the async callback to OnMesssageSent
                client.BeginSend(sendBytes, 0, sendBytes.Length, SocketFlags.None, New AsyncCallback(AddressOf OnMessageSent), client)

                Return True
            Catch
                Return False
            End Try
        End Function

        Private Sub OnClientAccept(ByVal asyncres As IAsyncResult)
            Try
                'End accepting client and restart client acceptance
                clientSocket = serverSocket.EndAccept(asyncres)
                serverSocket.BeginAccept(New AsyncCallback(AddressOf OnClientAccept), Nothing)

                'Raise a new event letting the user know that a client has connected
                Dim e As New ClientConnectedEventArgs
                e.clientID = clientSocket.Handle.ToString
                e.clientSocket = clientSocket
                RaiseEvent ClientConnected(Me, e)

                'Start receiving messages from the client
                clientSocket.BeginReceive(byteSize, 0, byteSize.Length, SocketFlags.None, New AsyncCallback(AddressOf OnMessageReceive), clientSocket)

                'Begin constant check to see whether the client is still connected
            Catch ex As Exception
                'If error occurs, throw a new exception
                Throw New Exception("Failed to accept a client. See 'OnClientAccept' Sub. Details: " & ex.Message)
            End Try
        End Sub

        Private Sub OnMessageReceive(ByVal asyncres As IAsyncResult)
            Try
                'Create a socket to use with events
                Dim client As Socket = asyncres.AsyncState

                'If the client is not connected break and dispose the client
                If client.Connected = False And client.Poll(2000, SelectMode.SelectRead) Then
                    Exit Sub
                End If

                'Create a byte from the byteSize and set it to the message from the client
                Dim bytesRec As Byte() = byteSize
                Dim message As String = System.Text.ASCIIEncoding.ASCII.GetString(bytesRec).Trim()

                'Raise the MessageReceived Event with parameters specified above
                Dim e As New MessageReceivedEventArgs
                e.Sender = client.Handle.ToString
                e.Message = message
                e.clientSocket = client
                RaiseEvent MessageReceived(Me, e)
                'Start recieving data from the socket again
                clientSocket.BeginReceive(byteSize, 0, byteSize.Length, SocketFlags.None, New AsyncCallback(AddressOf OnMessageReceive), clientSocket)
            Catch
                'If error occurs, throw a new exception
                Throw New Exception("Failed to receive message from client or related")
            End Try
        End Sub

        Private Sub OnMessageSent(ByVal asyncres As IAsyncResult)
            Try
                Dim client As Socket = asyncres.AsyncState

                'Gracefully let the message sending be ended
                client.EndSend(asyncres)
            Catch
                'If error occurs, throw a new exception
                Throw New Exception("Failed to disconnect client")
            End Try
        End Sub

        Private Sub OnClientDisconnect(ByVal asyncres As IAsyncResult)
            Try
                'Define a socket and use it for the events, setting it to the asyncstate of the result
                Dim client As Socket = asyncres.AsyncState

                'Raise a new clientdisconnected event
                Dim e As New ClientDisconnectedEventArgs
                e.clientID = client.Handle.ToString
                e.clientSocket = client
                RaiseEvent ClientDisconnected(Me, e)

                'End the disconnect sequence
                client.EndDisconnect(asyncres)
            Catch
                'If error occurs, throw a new exception
                Throw New Exception("Failed to disconnect client")
            End Try
        End Sub

        ''' <summary>
        ''' Checks whether a socket is alive by polling it
        ''' </summary>
        ''' <param name="socket">The socket you wish to check</param>
        ''' <returns></returns>
        ''' <remarks></remarks>
        Public Function IsConnected(ByVal socket As Socket) As Boolean
            Try
                'Check whether socket is alive by polling it.
                Return Not (socket.Poll(1, SelectMode.SelectRead) AndAlso socket.Available = 0)
            Catch ex As SocketException
                Return False
            End Try
        End Function
    End Class

    Public Class MessageReceivedEventArgs
        Inherits EventArgs
        Public Sender As String
        Public clientSocket As Socket
        Public Message As String
    End Class

    Public Class ClientConnectedEventArgs
        Inherits EventArgs
        Public clientID As String
        Public clientSocket As Socket
    End Class

    Public Class ClientDisconnectedEventArgs
        Inherits EventArgs
        Public clientID As String
        Public clientSocket As Socket
    End Class
End Namespace