如何连接到TCP套接字，在接收数据之前发送数据进行授权

Question

I am using Rx to connect to a Socket and receive data. The issue I have is that after connecting to the Socket I need to send data for authorization before data can be received.

Connection

public static IObservable<Unit> WhenConnected(this Socket socket, IPAddress address, int port)
{
    return Observable.FromAsyncPattern<IPAddress, int>(
        socket.BeginConnect,
        socket.EndConnect)(address, port);
}

Receive Data

Won't post all the code but in summary it uses TakeWhile to repeatedly receive bytes from the Begin/End Receive async methods.

var receiveData = Observable.FromAsyncPattern
    <byte[], int, int, SocketFlags, int>(socket.BeginReceive, socket.EndReceive);

Question 1:

Now my issue is how do I go about constructing my subscription?

var query = from _ in socket.WhenConnected(IPAddress.Parse(_host), _port)
            //need to authorize before receiving data
            from value socket.DataReceived().Repeat()
            select value;

using (query.Subscribe(...

Question 2

Usually I would send packets of information using a NetworkStream rather than a Socket so would I need to do something completely different?

Answer 1

The Rxx library has some extension methods that are very helpful for this sort of operation. Inside the StreamExtensions.cs of version 1.3, there is

public static IObservable<byte[]> ReadObservable(this Stream stream, int count)

and

public static IObservable<Unit> WriteObservable(this Stream stream, byte[] buffer, int offset, int count)

which can be used on a network stream. I'm not sure if the following is the best way, but it could be set up as follows:

NetworkStream networkStream = null;
var setupStreamPlan = Observable
  .When(WhenConnected(...))
  .Then(_ => networkStream = new NetworkStream(socket));
var authorizePlan = Observable
  .When(setupStreamPlan)
  .Then(_ => networkStream.WriteObserable(/*message to write*/);
var listenPlan = Observable
  .When(authorizePlan)
  .Then(_ => networkStream.ReadObservable(10).Repeat());
var constantSizeMessageStream = Observable
  .When(listenPlan)
  .Switch();

EDIT: Allowed for networkStream to be set up