VB.NET SocketPermission类代码示例

' Creates a SocketPermission restricting access to and from all URIs.
   Dim mySocketPermission1 As New SocketPermission(PermissionState.None)
   
   ' The socket to which this permission will apply will allow connections from www.contoso.com.
   mySocketPermission1.AddPermission(NetworkAccess.Accept, TransportType.Tcp, "www.contoso.com", 11000)
   
   ' Creates a SocketPermission which will allow the target Socket to connect with www.southridgevideo.com.
   Dim mySocketPermission2 As New SocketPermission(NetworkAccess.Connect, TransportType.Tcp, "www.southridgevideo.com", 11002)
   
   ' Creates a SocketPermission from the union of two SocketPermissions.
   Dim mySocketPermissionUnion As SocketPermission = CType(mySocketPermission1.Union(mySocketPermission2), SocketPermission)
   
   ' Checks to see if the union was successfully created by using the IsSubsetOf method.
   If mySocketPermission1.IsSubsetOf(mySocketPermissionUnion) And mySocketPermission2.IsSubsetOf(mySocketPermissionUnion) Then
      Console.WriteLine("This union contains permissions from both mySocketPermission1 and mySocketPermission2")
      
      ' Prints the allowable accept URIs to the console.
      Console.WriteLine("This union accepts connections on :")
      
      Dim myEnumerator As IEnumerator = mySocketPermissionUnion.AcceptList
      While myEnumerator.MoveNext()
         Console.WriteLine(CType(myEnumerator.Current, EndpointPermission).ToString())
      End While
      
      Console.WriteLine("This union establishes connections on : ")
      
      ' Prints the allowable connect URIs to the console.
      Console.WriteLine("This union permits connections to :")
      
      myEnumerator = mySocketPermissionUnion.ConnectList
      While myEnumerator.MoveNext()
         Console.WriteLine(CType(myEnumerator.Current, EndpointPermission).ToString())
      End While
   End If 
   ' Creates a SocketPermission from the intersect of two SocketPermissions.
   Dim mySocketPermissionIntersect As SocketPermission = CType(mySocketPermission1.Intersect(mySocketPermissionUnion), SocketPermission)
   
   ' mySocketPermissionIntersect should now contain the permissions of mySocketPermission1.
   If mySocketPermission1.IsSubsetOf(mySocketPermissionIntersect) Then
      Console.WriteLine("This is expected")
   End If
   ' mySocketPermissionIntersect should not contain the permissios of mySocketPermission2.
   If mySocketPermission2.IsSubsetOf(mySocketPermissionIntersect) Then
      Console.WriteLine("This should not print")
   End If
   
   ' Creates a copy of the intersect SocketPermission.
   Dim mySocketPermissionIntersectCopy As SocketPermission = CType(mySocketPermissionIntersect.Copy(), SocketPermission)
   
   If mySocketPermissionIntersectCopy.Equals(mySocketPermissionIntersect) Then
      Console.WriteLine("Copy successfull")
   End If
   ' Converts a SocketPermission to XML format and then immediately converts it back to a SocketPermission.
   mySocketPermission1.FromXml(mySocketPermission1.ToXml())
   
   
   ' Checks to see if permission for this socket resource is unrestricted.  If it is, then there is no need to
   ' demand that permissions be enforced.
   If mySocketPermissionUnion.IsUnrestricted() Then
   
   'Do nothing.  There are no restrictions.
   Else
      ' Enforces the permissions found in mySocketPermissionUnion on any Socket Resources used below this statement. 
      mySocketPermissionUnion.Demand()
   End If
   
   Dim myIpHostEntry As IPHostEntry = Dns.Resolve("www.contoso.com")
   Dim myLocalEndPoint As New IPEndPoint(myIpHostEntry.AddressList(0), 11000)
   
   Dim s As New Socket(myLocalEndPoint.Address.AddressFamily, SocketType.Stream, ProtocolType.Tcp)
   Try
      s.Connect(myLocalEndPoint)
   Catch e As Exception
      Console.WriteLine(("Exception Thrown: " + e.ToString()))
   End Try
   
   ' Perform all socket operations in here.
   s.Close()
End Sub