238 lines
12 KiB
C#
238 lines
12 KiB
C#
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//------------------------------------------------------------------------------
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// <copyright file="WebSocketPipe.cs" company="Microsoft">
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// Copyright (c) Microsoft Corporation. All rights reserved.
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// </copyright>
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//------------------------------------------------------------------------------
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namespace System.Web.WebSockets {
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using System;
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using System.Diagnostics.CodeAnalysis;
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using System.Net.WebSockets;
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using System.Runtime.InteropServices;
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using System.Security.Permissions;
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using System.Threading.Tasks;
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using System.Web.Util;
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// Used to send and receive messages over a WebSocket connection
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[SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode = true)]
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internal sealed class WebSocketPipe : IWebSocketPipe {
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// Managed representation (bindable as an anonymous delegate) of work that can be called by the thunk
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private delegate void CompletionCallback(int hrError, int cbIO, bool fUtf8Encoded, bool fFinalFragment, bool fClose);
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// Corresponds to the unmanaged PFN_WEBSOCKET_COMPLETION delegate
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private delegate void CompletionCallbackThunk(int hrError, IntPtr pvCompletionContext, int cbIO, bool fUtf8Encoded, bool fFinalFragment, bool fClose);
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private static readonly CompletionCallbackThunk _asyncThunk = AsyncCallbackThunk; // need to root the delegate itself so not collected while unmanaged code executing
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[SuppressMessage("Microsoft.Reliability", "CA2006:UseSafeHandleToEncapsulateNativeResources", Justification = @"This is a function pointer whose lifetime lasts for the entire duration of this AppDomain. We never need to release it.")]
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private static readonly IntPtr _asyncThunkAddress = Marshal.GetFunctionPointerForDelegate(_asyncThunk);
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private readonly IUnmanagedWebSocketContext _context;
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private readonly IPerfCounters _perfCounters;
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internal WebSocketPipe(IUnmanagedWebSocketContext context, IPerfCounters perfCounters) {
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_context = context;
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_perfCounters = perfCounters;
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}
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public Task WriteFragmentAsync(ArraySegment<byte> buffer, bool isUtf8Encoded, bool isFinalFragment) {
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TaskCompletionSource<object> tcs = new TaskCompletionSource<object>();
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// The buffer will be read from asynchronously by unmanaged code, so we require that it remain pinned
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PinnedArraySegment<byte> pinnedBuffer = new PinnedArraySegment<byte>(buffer);
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// Callback will always be called (since it is responsible for cleanup), even if completed synchronously
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CompletionCallback callback = (hrError, cbIO, fUtf8Encoded, fFinalFragment, fClose) => {
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try {
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ThrowExceptionForHR(hrError);
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tcs.TrySetResult(null); // regular completion
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}
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catch (Exception ex) {
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tcs.TrySetException(ex); // exceptional completion
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}
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finally {
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// Always free the buffer to prevent a memory leak
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pinnedBuffer.Dispose();
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}
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};
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IntPtr completionContext = GCUtil.RootObject(callback);
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// update perf counter with count of data written to wire
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_perfCounters.IncrementCounter(AppPerfCounter.REQUEST_BYTES_OUT_WEBSOCKETS, pinnedBuffer.Count);
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// Call the underlying implementation; WriteFragment should never throw an exception
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int bytesSent = pinnedBuffer.Count;
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bool completionExpected;
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int hr = _context.WriteFragment(
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pData: pinnedBuffer.Pointer,
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pcbSent: ref bytesSent,
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fAsync: true,
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fUtf8Encoded: isUtf8Encoded,
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fFinalFragment: isFinalFragment,
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pfnCompletion: _asyncThunkAddress,
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pvCompletionContext: completionContext,
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pfCompletionExpected: out completionExpected);
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if (!completionExpected) {
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// Completed synchronously or error; the thunk and callback together handle cleanup
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AsyncCallbackThunk(hr, completionContext, bytesSent, isUtf8Encoded, isFinalFragment, fClose: false);
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}
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return tcs.Task;
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}
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public Task WriteCloseFragmentAsync(WebSocketCloseStatus closeStatus, string statusDescription) {
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TaskCompletionSource<object> tcs = new TaskCompletionSource<object>();
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// Callback will always be called (since it is responsible for cleanup), even if completed synchronously
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CompletionCallback callback = (hrError, cbIO, fUtf8Encoded, fFinalFragment, fClose) => {
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try {
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ThrowExceptionForHR(hrError);
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tcs.TrySetResult(null); // regular completion
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}
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catch (Exception ex) {
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tcs.TrySetException(ex); // exceptional completion
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}
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};
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IntPtr completionContext = GCUtil.RootObject(callback);
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// Call the underlying implementation; SendConnectionClose should never throw an exception
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bool completionExpected;
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int hr = _context.SendConnectionClose(
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fAsync: true,
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uStatusCode: (ushort)closeStatus,
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szReason: statusDescription, // don't need to pin string: CLR marshaler handles managed to unmanaged conversion, and IIS makes local copy for duration of async operation
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pfnCompletion: _asyncThunkAddress,
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pvCompletionContext: completionContext,
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pfCompletionExpected: out completionExpected);
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if (!completionExpected) {
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// Completed synchronously or error; the thunk and callback together handle cleanup
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AsyncCallbackThunk(hr, completionContext, cbIO: 0, fUtf8Encoded: true, fFinalFragment: true, fClose: false);
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}
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return tcs.Task;
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}
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public Task<WebSocketReceiveResult> ReadFragmentAsync(ArraySegment<byte> buffer) {
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TaskCompletionSource<WebSocketReceiveResult> tcs = new TaskCompletionSource<WebSocketReceiveResult>();
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// The buffer will be written to asynchronously by unmanaged code, so we require that it remain pinned
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PinnedArraySegment<byte> pinnedBuffer = new PinnedArraySegment<byte>(buffer);
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// Callback will always be called (since it is responsible for cleanup), even if completed synchronously
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CompletionCallback callback = (hrError, cbIO, fUtf8Encoded, fFinalFragment, fClose) => {
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try {
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ThrowExceptionForHR(hrError);
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WebSocketCloseStatus? closeStatus = null;
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string closeStatusDescription = null;
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WebSocketMessageType messageType = (fUtf8Encoded) ? WebSocketMessageType.Text : WebSocketMessageType.Binary;
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if (fClose) {
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// this is a CLOSE frame
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messageType = WebSocketMessageType.Close;
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WebSocketCloseStatus statusCode;
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GetCloseStatus(out statusCode, out closeStatusDescription);
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closeStatus = statusCode;
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}
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else {
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// this is a data frame, so update perf counter with count of data read from wire
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_perfCounters.IncrementCounter(AppPerfCounter.REQUEST_BYTES_IN_WEBSOCKETS, cbIO);
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}
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tcs.TrySetResult(new WebSocketReceiveResult(
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count: cbIO,
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messageType: messageType,
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endOfMessage: fFinalFragment,
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closeStatus: closeStatus,
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closeStatusDescription: closeStatusDescription));
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}
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catch (Exception ex) {
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tcs.TrySetException(ex); // exceptional completion
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}
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finally {
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// Always free the buffer to prevent a memory leak
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pinnedBuffer.Dispose();
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}
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};
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IntPtr completionContext = GCUtil.RootObject(callback);
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// Call the underlying implementation; ReadFragment should never throw an exception
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int bytesRead = pinnedBuffer.Count;
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bool isUtf8Encoded;
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bool isFinalFragment;
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bool isConnectionClose;
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bool completionExpected;
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int hr = _context.ReadFragment(
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pData: pinnedBuffer.Pointer,
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pcbData: ref bytesRead,
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fAsync: true,
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pfUtf8Encoded: out isUtf8Encoded,
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pfFinalFragment: out isFinalFragment,
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pfConnectionClose: out isConnectionClose,
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pfnCompletion: _asyncThunkAddress,
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pvCompletionContext: completionContext,
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pfCompletionExpected: out completionExpected);
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if (!completionExpected) {
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// Completed synchronously or error; the thunk and callback together handle cleanup
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AsyncCallbackThunk(hr, completionContext, bytesRead, isUtf8Encoded, isFinalFragment, isConnectionClose);
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}
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return tcs.Task;
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}
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// Gets the reason (numeric + textual) the client sent a CLOSE frame to the server.
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// Returns false if no reason was given.
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private void GetCloseStatus(out WebSocketCloseStatus closeStatus, out string closeStatusDescription) {
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ushort statusCode;
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IntPtr reasonPtr;
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ushort reasonLength;
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int hr = _context.GetCloseStatus(out statusCode, out reasonPtr, out reasonLength);
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if (hr == HResults.E_NOT_SET) {
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// This HRESULT is special-cased to mean that a status code has not been provided.
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statusCode = 0;
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reasonPtr = IntPtr.Zero;
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}
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else {
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// Any other HRESULTs must be treated as exceptional.
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ThrowExceptionForHR(hr);
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}
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// convert the status code and description string
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closeStatus = (WebSocketCloseStatus)statusCode;
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if (reasonPtr != IntPtr.Zero) {
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unsafe {
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// return a managed copy of the string (IIS will free the original memory)
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closeStatusDescription = new String((char*)reasonPtr, 0, reasonLength);
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}
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}
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else {
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closeStatusDescription = null;
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}
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}
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public void CloseTcpConnection() {
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_context.CloseTcpConnection();
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}
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// This thunk dispatches to the appropriate instance continuation when an asynchronous event completes
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private static void AsyncCallbackThunk(int hrError, IntPtr pvCompletionContext, int cbIO, bool fUtf8Encoded, bool fFinalFragment, bool fClose) {
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// Calling UnrootObject also makes the callback and everything it references eligible for garbage collection
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CompletionCallback callback = (CompletionCallback)GCUtil.UnrootObject(pvCompletionContext);
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callback(hrError, cbIO, fUtf8Encoded, fFinalFragment, fClose);
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}
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private static void ThrowExceptionForHR(int hrError) {
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// We should homogenize errors coming from the native layer into a WebSocketException.
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if (hrError < 0) {
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throw new WebSocketException(hrError);
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}
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}
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}
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}
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