TCP/IP 消息成帧

Question

我制作了一个 TCP/IP 服务器/客户端，它是异步的，但它连接了消息。如何正确地在开头添加标头，然后在结尾使用字符串生成器来取消连接完整的消息。

服务器读取消息：

  Private Sub ReadCallback(ByVal result As IAsyncResult)
    Try
        allDone.Set()
        Dim success As Boolean = result.AsyncWaitHandle.WaitOne(500, True)
        If success Then
            Dim client As ServerClient = TryCast(result.AsyncState, ServerClient)
            If client Is Nothing Then
                Return
            End If
            Dim networkStream As NetworkStream = client.NetworkStream
            Dim read As Integer = networkStream.EndRead(result)
            If read = 0 Then
                SyncLock Me.Clients
                    Me.Clients.Remove(client.ClientID)
                    Return
                End SyncLock
            End If
            If client.NetworkStream.CanRead Then

                dataString.Append(Me.Encoding.GetString(client.buffer, 0, read))

                networkStream.BeginRead(client.buffer, 0, client.buffer.Length, AddressOf ReadCallback, client)
                allDone.WaitOne(500, True)
            End If
        End If
    Catch ex As IO.IOException
        Dim client As ServerClient = TryCast(result.AsyncState, ServerClient)
        SyncLock Me.Clients
            Me.Clients.Remove(client.ClientID)
            Return
        End SyncLock
    Catch ex As Exception
        If Not Me.tcpListener.Server.Connected Then
            Return
        End If
    End Try
End Sub

客户端写消息：

    Public Function Write(value As String, encoding As Encoding) As Guid
    Dim buffer As Byte() = encoding.GetBytes(value)
    Return Me.Write(buffer)
End Function

Public Function Write(buffer As Byte()) As Guid
    Dim guid__1 As Guid = Guid.NewGuid()
    Dim networkStream As NetworkStream = Me.client.GetStream()
    Dim result As IAsyncResult = networkStream.BeginWrite(buffer, 0, buffer.Length, Nothing, guid__1)


    result.AsyncWaitHandle.WaitOne()
    networkStream.EndWrite(result)
    Return guid__1
End Function

Answer 1

您需要在 TCP/IP 之上定义一个（可能很简单）协议，以便让您知道一条消息在哪里开始和结束。 TCP/IP 可以并且将会对您发送的消息进行分段，以便接收者可以获得消息的一部分、整个消息或多条消息。一个简单的方法是写一个消息长度，然后是消息。然后接收者读入一个字节缓冲区，一旦接收到适当数量的字节（基于发送的长度），就可以提取消息并将其编码成一个字符串。