Thread Safe Dictionary Collection in VB.NET

Introduction

In Multi threaded application, it is essential to have thread safe collection. Provided below the SafeDictionary class built over Dictionary object.

Note: To iterate each item in collection, avoid "For each" loop & use "CopyTo", so that the collection values will be moved to another array & you can loop that array.

SafeDictionary.vb

Public Class SafeDictionary(Of TKey, TValue)
 Implements IDictionary(Of TKey, TValue)
 Private _rwLock As New Threading.ReaderWriterLockSlim
 Private _dict As New Generic.Dictionary(Of TKey, TValue)

 Private Class AcquireWriteLock
     Implements IDisposable
     Private _rwLock As New Threading.ReaderWriterLockSlim
     Public Sub New(ByVal rwLock As Threading.ReaderWriterLockSlim)
         _rwLock = rwLock
         _rwLock.EnterWriteLock()
     End Sub
     Private disposedValue As Boolean = False                ' To detect redundant calls

     ' IDisposable
     Protected Overridable Sub Dispose(ByVal disposing As Boolean)
         If Not Me.disposedValue Then
             If disposing Then
                 ' TODO: free other state (managed objects).
                 _rwLock.ExitWriteLock()
             End If
             ' TODO: free your own state (unmanaged objects).
             ' TODO: set large fields to null.
         End If
         Me.disposedValue = True
     End Sub
#Region " IDisposable Support "
     ' This code added by Visual Basic to correctly implement the disposable pattern.
     Public Sub Dispose() Implements IDisposable.Dispose
         ' Do not change this code.  Put cleanup code in Dispose(ByVal disposing As Boolean) above.
         Dispose(True)
         GC.SuppressFinalize(Me)
     End Sub
#End Region
 End Class
 Private Class AcquireReadLock
     Implements IDisposable
     Private _rwLock As New Threading.ReaderWriterLockSlim
     Public Sub New(ByVal rwLock As Threading.ReaderWriterLockSlim)
         _rwLock = rwLock
         _rwLock.EnterReadLock()
     End Sub
     Private disposedValue As Boolean = False                ' To detect redundant calls

     ' IDisposable
     Protected Overridable Sub Dispose(ByVal disposing As Boolean)
         If Not Me.disposedValue Then
             If disposing Then
                 ' TODO: free other state (managed objects).
                 _rwLock.ExitReadLock()
             End If
             ' TODO: free your own state (unmanaged objects).
             ' TODO: set large fields to null.
         End If
         Me.disposedValue = True
     End Sub
#Region " IDisposable Support "
     ' This code added by Visual Basic to correctly implement the disposable pattern.
     Public Sub Dispose() Implements IDisposable.Dispose
         ' Do not change this code.  Put cleanup code in Dispose(ByVal disposing As Boolean) above.
         Dispose(True)
         GC.SuppressFinalize(Me)
     End Sub
#End Region
 End Class
 Public Sub Add(ByVal item As System.Collections.Generic.KeyValuePair(Of TKey, TValue)) Implements System.Collections.Generic.ICollection(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)).Add
     Using New AcquireWriteLock(_rwLock)
         _dict(item.Key) = item.Value
     End Using
 End Sub
 Public Sub Clear() Implements System.Collections.Generic.ICollection(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)).Clear
     Using New AcquireWriteLock(_rwLock)
         _dict.Clear()
     End Using
 End Sub
 Public Function Contains(ByVal item As System.Collections.Generic.KeyValuePair(Of TKey, TValue)) As Boolean Implements System.Collections.Generic.ICollection(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)).Contains
     Using New AcquireReadLock(_rwLock)
         Return _dict.Contains(item)
     End Using
 End Function

 Public Sub CopyTo(ByVal array() As System.Collections.Generic.KeyValuePair(Of TKey, TValue), ByVal arrayIndex As Integer) Implements System.Collections.Generic.ICollection(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)).CopyTo
     Using New AcquireReadLock(_rwLock)
         _dict.ToArray.CopyTo(array, arrayIndex)
     End Using
 End Sub

 Public ReadOnly Property Count() As Integer Implements System.Collections.Generic.ICollection(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)).Count
     Get
         Using New AcquireReadLock(_rwLock)
             Return _dict.Count
         End Using
     End Get
 End Property
 Public ReadOnly Property IsReadOnly() As Boolean Implements System.Collections.Generic.ICollection(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)).IsReadOnly
     Get
         Return False
     End Get
 End Property
 Public Function Remove(ByVal item As System.Collections.Generic.KeyValuePair(Of TKey, TValue)) As Boolean Implements System.Collections.Generic.ICollection(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)).Remove
     Using New AcquireWriteLock(_rwLock)
         Return _dict.Remove(item.Key)
     End Using
 End Function

 Public Sub Add(ByVal key As TKey, ByVal value As TValue) Implements System.Collections.Generic.IDictionary(Of TKey, TValue).Add
     Using New AcquireWriteLock(_rwLock)
         _dict(key) = value
     End Using
 End Sub

 Public Function ContainsKey(ByVal key As TKey) As Boolean Implements System.Collections.Generic.IDictionary(Of TKey, TValue).ContainsKey
     Using New AcquireReadLock(_rwLock)
         Return _dict.ContainsKey(key)
     End Using
 End Function
 Default Public Property Item(ByVal key As TKey) As TValue Implements System.Collections.Generic.IDictionary(Of TKey, TValue).Item
     Get
         Using New AcquireReadLock(_rwLock)
             Return _dict(key)
         End Using
     End Get
     Set(ByVal value As TValue)
         Using New AcquireWriteLock(_rwLock)
             _dict(key) = value
         End Using
     End Set
 End Property
 Public ReadOnly Property Keys() As System.Collections.Generic.ICollection(Of TKey) Implements System.Collections.Generic.IDictionary(Of TKey, TValue).Keys
     Get
         Using New AcquireReadLock(_rwLock)
             Return _dict.Keys
         End Using
     End Get
 End Property
 Public Function Remove(ByVal key As TKey) As Boolean Implements System.Collections.Generic.IDictionary(Of TKey, TValue).Remove
     Using New AcquireWriteLock(_rwLock)
         Return _dict.Remove(key)
     End Using
 End Function

 Public Function TryGetValue(ByVal key As TKey, ByRef value As TValue) As Boolean Implements System.Collections.Generic.IDictionary(Of TKey, TValue).TryGetValue
     Using New AcquireReadLock(_rwLock)
         Return _dict.TryGetValue(key, value)
     End Using
 End Function

 Public ReadOnly Property Values() As System.Collections.Generic.ICollection(Of TValue) Implements System.Collections.Generic.IDictionary(Of TKey, TValue).Values
     Get
         Using New AcquireReadLock(_rwLock)
             Return _dict.Values
         End Using
     End Get
 End Property
 Public Function GetEnumeratorGeneric() As System.Collections.Generic.IEnumerator(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)) Implements System.Collections.Generic.IEnumerable(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)).GetEnumerator
     Using New AcquireReadLock(_rwLock)
         Return _dict.GetEnumerator
     End Using
 End Function
 Public Function GetEnumerator() As System.Collections.IEnumerator Implements System.Collections.IEnumerable.GetEnumerator
     Using New AcquireReadLock(_rwLock)
         Return _dict.GetEnumerator
     End Using
 End Function
End Class

Happy Coding!

Connecting Socks Proxy Server in VB.NET

Introduction

Using  Windows Socket we can connect to any destination via Socks Proxy. 

How it works:

Connecting without proxy:

1. Request Connection to DestinationServer:DestinationPort

2. Destination Connected 

3. Start Receiving/Sending Data to Destination

Connecting with proxy: 

1. Request Connection to ProxyServer:ProxyPort

2. If needed, provide Authentication Details for proxy server

3. ProxyServer connected

4. Passing our DestinationServer/port Details to Proxy Server

5. ProxyServer itself connects to the DestinationServer

6. Start Receiving/Sending Data to Destination

Code

Lets have 2 reusable class files for Proxy Connection

Proxy.vb

Public MustInherit Class Proxy
Private _server As String
Private _port As Integer
Private _user As String
Private _password As String
Public Property Server() As String
   Get
       Return _server
   End Get
   Set(ByVal value As String)
       _server = value
   End Set
End Property
Public Property Port() As Integer
   Get
       Return _port
   End Get
   Set(ByVal value As Integer)
       _port = value
   End Set
End Property
Public Property User() As String
   Get
       Return _user
   End Get
   Set(ByVal value As String)
       _user = User
   End Set
End Property
Public Property Password() As String
   Get
       Return _password
   End Get
   Set(ByVal value As String)
       _password = Password
   End Set
End Property
Public ReadOnly Property ProxyIPEndPoint() As IPEndPoint
   Get
       Return New IPEndPoint(Dns.GetHostEntry(_server).AddressList(0), _port)
   End Get
End Property
Public Sub New(ByVal Server As String, ByVal Port As Integer, ByVal User As String, ByVal Password As String)
   _server = Server
   _port = Port
   _user = User
   _password = Password
End Sub

End Class

SocksProxy.vb

Imports System.Net.Sockets
Imports System.Net
Imports System.Text



Public Class SocksProxy
Inherits Proxy
Private _cSocket As Socket
Private _destHost As String
Private _destPort As String
Enum ProxyState
RequestAuthenticate
Authenticate
     ConnectServer
     Done
End Enum
Private sPxy As ProxyState
Private Const BUFFER_SIZE As Integer = 512
Private transferBuffer(BUFFER_SIZE) As Byte
Public Event Completed(ByVal sender As Object, ByVal e As SocketAsyncEventArgs)
Public Sub New(ByVal Server As String, ByVal Port As Integer, ByVal User As String, ByVal Password As String)
MyBase.New(Server, Port, User, Password)
End Sub
Public Sub New(ByVal p As Proxy)
MyBase.New(p.Server, p.Port, p.User, p.Password)
End Sub

Public Sub Connect(ByVal s As Socket, ByVal destHost As String, ByVal destPort As Integer)
Dim connectEventArgs As New SocketAsyncEventArgs
_destHost = destHost
_destPort = destPort
_cSocket = s
connectEventArgs.RemoteEndPoint = ProxyIPEndPoint
AddHandler connectEventArgs.Completed, AddressOf connectEventProxyArgs_Completed
_cSocket.ConnectAsync(connectEventArgs)
End Sub
#Region "SOCKS5 Proxy Functions"
Private Sub connectEventProxyArgs_Completed(ByVal sender As Object, ByVal e As SocketAsyncEventArgs)
If e.SocketError <> SocketError.Success Then
 Throw New Exception(e.SocketError.ToString)
 Return
End If

RemoveHandler e.Completed, AddressOf connectEventProxyArgs_Completed
     AddHandler e.Completed, AddressOf receiveEventProxyArgs_Completed

     e.SetBuffer(transferBuffer, 0, transferBuffer.Length)
     _cSocket.ReceiveAsync(e)

sPxy = ProxyState.RequestAuthenticate
sendProxyData()
End Sub
Private Sub receiveEventProxyArgs_Completed(ByVal sender As Object, ByVal e As SocketAsyncEventArgs)
If e.SocketError <> SocketError.Success Then
 Throw New Exception(e.SocketError.ToString)
 Return
End If
Try
 Dim bRec(e.BytesTransferred) As Byte
 Buffer.BlockCopy(transferBuffer, e.Offset, bRec, 0, e.BytesTransferred)
 Process_Proxy_Data(bRec, e)
         If sPxy <> ProxyState.Done Then _cSocket.ReceiveAsync(e)
Catch ex As Exception
 Throw New Exception(ex.Message)
End Try

End Sub
Private Sub sendProxyData()
Dim request(257) As Byte
Dim rawBytes() As Byte
Dim nIndex As UShort = 0
Try
 Select Case sPxy
   Case ProxyState.RequestAuthenticate
     request(nIndex) = &H5 : nIndex += 1 ' Version 5.
     If User <> "" Then 'only if provided
       request(nIndex) = &H2 : nIndex += 1 '  2 Authentication methods are in packet...
       request(nIndex) = &H0 : nIndex += 1  ' NO AUTHENTICATION REQUIRED
       request(nIndex) = &H2 : nIndex += 1  ' USERNAME/PASSWORD
     Else
       request(nIndex) = &H1 : nIndex += 1 '  1 Authentication method in packet...
       request(nIndex) = &H0 : nIndex += 1  ' NO AUTHENTICATION REQUIRED
     End If
     ' Send the authentication negotiation request...
                 _cSocket.Send(request, nIndex, SocketFlags.None)
             Case ProxyState.Authenticate
                 'Username/Password Authentication protocol
                 request(nIndex) = &H1 : nIndex += 1    ' Current version of the subnegotiation.
                 ' add user name
                 request(nIndex) = CType(User.Length, Byte) : nIndex += 1
                 rawBytes = Encoding.Default.GetBytes(User)
                 rawBytes.CopyTo(request, nIndex)
                 nIndex += CType(rawBytes.Length, UShort)

                 ' add password
                 request(nIndex) = CType(Password.Length, Byte) : nIndex += 1
                 rawBytes = Encoding.Default.GetBytes(Password)
                 rawBytes.CopyTo(request, nIndex)
                 nIndex += CType(rawBytes.Length, UShort)

                 ' Send the Username/Password request
                 _cSocket.Send(request, nIndex, SocketFlags.None)
   Case ProxyState.ConnectServer
     Dim destIP As IPAddress = Nothing
     Try
       destIP = IPAddress.Parse(_destHost)
     Catch ex As Exception
     End Try
     request(nIndex) = &H5 : nIndex += 1 ' version 5.
     request(nIndex) = &H1 : nIndex += 1 ' command = connect.(connect=1; bind=2; UDP=3)
     request(nIndex) = &H0 : nIndex += 1 ' Reserve = must be 0x00

     If (Not destIP Is Nothing) Then
       ' Destination adress in an IP.
       Select Case (destIP.AddressFamily)
         Case AddressFamily.InterNetwork
           ' Address is IPV4 format(IP-V4=1; domain name=3; IP-V6=4)
           request(nIndex) = &H1 : nIndex += 1
           rawBytes = destIP.GetAddressBytes()
           rawBytes.CopyTo(request, nIndex)
           nIndex += CType(rawBytes.Length, UShort)
         Case AddressFamily.InterNetworkV6
           ' Address is IPV6 format
           request(nIndex) = &H4 : nIndex += 1
           rawBytes = destIP.GetAddressBytes()
           rawBytes.CopyTo(request, nIndex)
           nIndex += CType(rawBytes.Length, UShort)
       End Select
     Else
       ' Dest. address is domain name.
       request(nIndex) = &H3 : nIndex += 1 ' Address is full-qualified domain name.
       request(nIndex) = Convert.ToByte(_destHost.Length) : nIndex += 1 ' length of addres_cSocket.
       rawBytes = Encoding.Default.GetBytes(_destHost)
       rawBytes.CopyTo(request, nIndex)
       nIndex += CType(rawBytes.Length, Short)
     End If
     request(nIndex) = Convert.ToByte((_destPort And &HFF00) >> 8) : nIndex += 1
     request(nIndex) = Convert.ToByte(_destPort And &HFF) : nIndex += 1
     ' send connect request.
     _cSocket.Send(request, nIndex, SocketFlags.None)
 End Select
Catch ex As Exception
 Throw New Exception(ex.Message)
End Try
End Sub
Private Sub Process_Proxy_Data(ByVal pMessage() As Byte, ByVal e As SocketAsyncEventArgs)
If pMessage.Length < 2 Then Return
Dim response(257) As Byte

Dim nIndex As UShort = 0


Select Case sPxy
 Case ProxyState.RequestAuthenticate
   If pMessage(1) = &H0 Then
     'No Authentication required
     sPxy = ProxyState.ConnectServer
     sendProxyData()
   ElseIf pMessage(1) = &H2 Then
     'Authentication required
     sPxy = ProxyState.Authenticate
     sendProxyData()
   Else
     Throw New Exception("None of the authentication method was accepted by proxy server.")
   End If
 Case ProxyState.Authenticate
   If pMessage(1) = &H0 Then
     'Authentication Success
     sPxy = ProxyState.ConnectServer
     sendProxyData()
   Else
     Throw New Exception("Bad Username/Password.")
   End If
 Case ProxyState.ConnectServer
   If pMessage(1) = &H0 Then
     'Connected
                 ' Change the Handler to Regular Receive Event
                 RemoveHandler e.Completed, AddressOf receiveEventProxyArgs_Completed
                 sPxy = ProxyState.Done
     RaiseEvent Completed(_cSocket, e)
   Else
     Throw New Exception("Unable to connect Proxy Server.")
             End If
     End Select
End Sub
#End Region
End Class

After including the above 2 class files, you can connect to a destination either directly or via proxy(if defined)

 Public Class MyClass
Private _cSocket As Socket

Public Function Connect() As Boolean
Dim server As String = "[destinationServer]"
Dim port As Integer ="[destinationPort]"
Dim clientproxy As Proxy = Nothing

  clientproxy=new Proxy("[proxyServer]","[proxyPort]","[uname]","[pwd]")

  _cSocket = New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)
  Dim connectEventArgs As New SocketAsyncEventArgs

        If clientproxy Is Nothing Then
            connectEventArgs.RemoteEndPoint = New IPEndPoint(Dns.GetHostEntry(server).AddressList(0), port)
            AddHandler connectEventArgs.Completed, AddressOf connectEventArgs_Completed
            _cSocket.ConnectAsync(connectEventArgs)
        Else
            socksProxy = New SocksProxy(clientproxy)
            AddHandler socksProxy.Completed, AddressOf connectEventArgs_Completed
            socksProxy.Connect(_cSocket, server, port)
        End If
  Return True

End Function

Private Sub connectEventArgs_Completed(ByVal sender As Object, ByVal e As SocketAsyncEventArgs)
            If e.SocketError = SocketError.Success Then
                RemoveHandler e.Completed, AddressOf connectEventArgs_Completed
                ReceiveBegin()
            End If
End Sub

Private Sub ReceiveBegin()
   ..........
..........

Hope it is simple. Happy Programming!