Rollback SendToAsync changes

It appears that for connectionless protocols, BeginSendTo modifies the Socket to include the endpoint targeted, whereas SendAsync does not... then if a subsequent BeginReceiveFrom was expecting the endpoint to be set, it'll fail.

Author: stephentoub

src/System.Net.Sockets/src/System/Net/Sockets/Socket.Tasks.cs

@@ -352,56 +352,14 @@ internal Task<int> SendAsync(IList<ArraySegment<byte>> buffers, SocketFlags sock
 
  internal Task<int> SendToAsync(ArraySegment<byte> buffer, SocketFlags socketFlags, EndPoint remoteEP)
  {
- // Validate the arguments.
- ValidateBuffer(buffer);
- if (remoteEP == null)
- {
- throw new ArgumentNullException(nameof(remoteEP));
- }
-
- // Get the SocketAsyncEventArgs instance to use for the operation.
- Int32TaskSocketAsyncEventArgs saea = RentSocketAsyncEventArgs(isReceive: false);
- if (saea == null)
+ var tcs = new TaskCompletionSource<int>(this);
+ BeginSendTo(buffer.Array, buffer.Offset, buffer.Count, socketFlags, remoteEP, iar =>
  {
- // We couldn't get a cached instance, which means there's already a receive operation
- // happening on this socket. Fall back to wrapping APM.
- var tcs = new TaskCompletionSource<int>(this);
- BeginSendTo(buffer.Array, buffer.Offset, buffer.Count, socketFlags, remoteEP, iar =>
- {
- var innerTcs = (TaskCompletionSource<int>)iar.AsyncState;
- try { innerTcs.TrySetResult(((Socket)innerTcs.Task.AsyncState).EndSendTo(iar)); }
- catch (Exception e) { innerTcs.TrySetException(e); }
- }, tcs);
- return tcs.Task;
- }
-
- // Configure the buffer. We don't clear the buffers when returning the SAEA to the pool,
- // so as to minimize overhead if the same buffer is used for subsequent operations (which is likely).
- // But SAEA doesn't support having both a buffer and a buffer list configured, so clear out a buffer list
- // if there is one before we set the desired buffer.
- if (saea.BufferList != null) saea.BufferList = null;
- saea.SetBuffer(buffer.Array, buffer.Offset, buffer.Count);
- saea.SocketFlags = socketFlags;
- saea.RemoteEndPoint = remoteEP;
-
- // Initiate the send
- Task<int> t;
- if (!SendToAsync(saea))
- {
- // The operation completed synchronously. Get a task for it and return the SAEA for future use.
- t = saea.SocketError == SocketError.Success ?
- GetSuccessTask(saea) :
- Task.FromException<int>(new SocketException((int)saea.SocketError));
- ReturnSocketAsyncEventArgs(saea, isReceive: false);
- }
- else
- {
- // The operation completed asynchronously. Get the task for the operation,
- // with appropriate synchronization to coordinate with the async callback
- // that'll be completing the task.
- t = saea.GetTaskSafe();
- }
- return t;
+ var innerTcs = (TaskCompletionSource<int>)iar.AsyncState;
+ try { innerTcs.TrySetResult(((Socket)innerTcs.Task.AsyncState).EndSendTo(iar)); }
+ catch (Exception e) { innerTcs.TrySetException(e); }
+ }, tcs);
+ return tcs.Task;
  }
 
  /// <summary>Validates the supplied array segment, throwing if its array or indices are null or out-of-bounds, respectively.</summary>
@@ -532,8 +490,6 @@ private void ReturnSocketAsyncEventArgs(Int32TaskSocketAsyncEventArgs saea, bool
  }
  else
  {
- saea.RemoteEndPoint = null; // will have been set for SendToAsync methods
-
  Debug.Assert(_cachedSendEventArgs == s_rentedSentinel);
  Volatile.Write(ref _cachedSendEventArgs, saea);
  }