Missing Socket APIs mega-issue

[geoffkizer]

We still have a few gaps in our Socket APIs where we are missing support for Task, Span/Memory, or CancellationToken.

This is a mega-issue to track all remaining work here for 6.0.

Async Socket APIs:

• AcceptAsync needs CancellationToken support -- implemented in add AcceptAsync cancellation overloads #53340

	public static ValueTask<Socket> AcceptAsync (this Socket socket, CancellationToken cancellationToken);
	public static ValueTask<Socket> AcceptAsync (this Socket socket, Socket acceptSocket, CancellationToken cancellationToken);

• SendToAsync, ReceiveFromAsync, and ReceiveMessageFromAsync need Memory and CancellationToken support -- see Socket API changes mega-issue #33418. (Note, this should probably wait until Sockets: Reimplement remaining Task-based async methods using SocketAsyncEventArgs  #41502 is completed.)

	public static ValueTask<int> SendToAsync(this Socket socket, ReadOnlyMemory<byte> buffer, SocketFlags socketFlags, EndPoint remoteEP, CancellationToken cancellationToken = null);
	public static ValueTask<SocketReceiveFromResult> ReceiveFromAsync(this Socket socket, Memory<byte> buffer, SocketFlags socketFlags, EndPoint remoteEP, CancellationToken cancellationToken = null);
	public static ValueTask<SocketReceiveMessageFromResult> ReceiveMessageFromAsync(this Socket socket, Memory<byte> buffer, SocketFlags socketFlags, EndPoint remoteEP, CancellationToken cancellationToken = null);

• Add Task-based SendFileAsync with Memory and CancellationToken support -- implemented in Socket.SendFileAsync based on SendPacketsAsync #52208 and implement cancellation support for SendFileAsync and DisconnectAsync #53062

 public ValueTask SendFileAsync(string? fileName, CancellationToken cancellationToken = default);
 public ValueTask SendFileAsync(string? fileName, ReadOnlyMemory<byte> preBuffer, ReadOnlyMemory<byte> postBuffer, TransmitFileOptions flags, CancellationToken cancellationToken = default);

• Add Task-based DisconnectAsync -- implemented in add Task-based DisconnectAsync and refactor APM methods on top of it #51213

 public static ValueTask DisconnectAsync(this Socket socket, bool reuseSocket, CancellationToken cancellationToken=default);

Sync Socket APIs:

• SendTo, ReceiveFrom, ReceiveMessageFrom need Span support -- implemented in Adds synchronous span APIs for datagram sockets. #51956 and adding span version of ReceiveMessageFrom #46285

	public int SendTo(ReadOnlySpan<byte> buffer, EndPoint remoteEP);
	public int SendTo(ReadOnlySpan<byte> buffer, SocketFlags socketFlags, EndPoint remoteEP);
	public int ReceiveFrom(Span<byte> buffer, ref EndPoint remoteEP);
	public int ReceiveFrom(Span<byte> buffer, SocketFlags socketFlags, ref EndPoint remoteEP);
 public int ReceiveMessageFrom(Span<byte> buffer, ref System.Net.Sockets.SocketFlags socketFlags, ref System.Net.EndPoint remoteEP, out System.Net.Sockets.IPPacketInformation ipPacketInformation);

• SendFile needs Span support -- implemented in Added Span overloads for Socket.SendFile #47230

 public void SendFile(string fileName, ReadOnlySpan<byte> preBuffer, ReadOnlySpan<byte> postBuffer, TransmitFileOptions flags);

Async TcpListener APIs:

• Accept async methods need CancellationToken support -- implemented in add AcceptAsync cancellation overloads #53340

	public ValueTask<Socket> AcceptSocketAsync (CancellationToken cancellationToken);
	public ValueTask<TcpClient> AcceptTcpClientAsync (CancellationToken cancellationToken);

Async TcpClient APIs:

• Add missing ConnectAsync overloads -- implemented in TcpClient.ConnectAsync(EndPoint) #44110

namespace System.Net.Sockets
{
 public class TcpClient : IDisposable
 {
 public Task ConnectAsync(IPEndPoint remoteEP);
 public ValueTask ConnectAsync(IPEndPoint remoteEP, CancellationToken cancellationToken);
 }
}

UdpClient APIs:

• UdpClient Span, Memory, and CancellationToken support -- see UdpClient - add Span support #864

public class UdpClient
{
 public int Send(ReadOnlySpan<byte> datagram);
 public int Send(ReadOnlySpan<byte> datagram, IPEndPoint endPoint);
 public int Send(ReadOnlySpan<byte> datagram, string hostname, int port);
 public ValueTask<int> SendAsync(ReadOnlyMemory<byte> datagram, CancellationToken cancellationToken);
 public ValueTask<int> SendAsync(ReadOnlyMemory<byte> datagram, IPEndPoint endPoint, CancellationToken cancellationToken);
 public ValueTask<UdpReceiveResult> ReceiveAsync(CancellationToken cancellationToken);
}

Related issues

• Move Task-based methods from SocketTaskExtensions to Socket -- see Move SocketTaskExtensions methods to Socket class itself #43901
• Memory support for SendPacketElements -- see Add Memory support to SendPacketElements #45267
• Consider overloads for Task-based methods that remove #SocketFlags argument -- see Consider adding Socket Send/ReceiveAsync overloads that elide SocketFlags argument #43934
• Remove Socket finalizer and ensure SafeSocketHandle finalization works correctly -- see Remove Socket finalizer and ensure SafeSocketHandle finalization works correctly #43383
• New APIs for zero-allocation connectionless sockets -- see Proposal: Zero allocation connectionless sockets #30797

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[GSPP]

Is it common policy to not provide CancellationToken support for synchronous APIs? It seems just as useful to have it for sync as it is for async.

[antonfirsov]

@GSPP for sockets, it's not possible to implement reliable cancellation of synchronous calls in a cross-platform way. From #42686 (comment):

Note that POSIX does not specify a way to abort on-going synchronous calls. The implementation is relying on OS specifics which work well on Linux, and less well on some other OSes. For best cross-platform behaviour applications should avoid using Dispose to abort on-going operations.

(#42686 is a typical issue around this problem)

[geoffkizer]

In general we don't provide CancellationToken support for sync APIs.

[karelz]

Triage: The APIs should be approved in the spin offs, not in this issue - this one is just tracking all the work.

Note: Some of the sub-issues are simple, so good for up-for-grabs.

[antonfirsov]

SendToAsync, ReceiveFromAsync, and ReceiveMessageFromAsync need Memory and CancellationToken support -- see #33148.

@geoffkizer you meant #938 I guess.