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HttpContent.cs
569 lines (488 loc) · 21.3 KB
/
HttpContent.cs
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using System.Diagnostics.Contracts;
using System.IO;
using System.Net.Http.Headers;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
namespace System.Net.Http
{
public abstract class HttpContent : IDisposable
{
private HttpContentHeaders headers;
private MemoryStream bufferedContent;
private bool disposed;
private Stream contentReadStream;
private bool canCalculateLength;
// We want the option to support larger buffers in the future (long), but for now Int32.MaxValue
// is MemoryStream's limit.
internal const long MaxBufferSize = Int32.MaxValue;
internal static readonly Encoding DefaultStringEncoding = Encoding.UTF8;
// These encodings have Byte-Order-Markers that we will use to detect the encoding.
private static Encoding[] EncodingsWithBom =
{
Encoding.UTF8, // EF BB BF
// UTF32 Must be before Unicode because its BOM is similar but longer.
Encoding.UTF32, // FF FE 00 00
Encoding.Unicode, // FF FE
Encoding.BigEndianUnicode, // FE FF
};
public HttpContentHeaders Headers
{
get
{
if (headers == null)
{
headers = new HttpContentHeaders(GetComputedOrBufferLength);
}
return headers;
}
}
private bool IsBuffered
{
get { return bufferedContent != null; }
}
protected HttpContent()
{
// Log to get an ID for the current content. This ID is used when the content gets associated to a message.
if (Logging.On) Logging.Enter(Logging.Http, this, ".ctor", null);
// We start with the assumption that we can calculate the content length.
this.canCalculateLength = true;
if (Logging.On) Logging.Exit(Logging.Http, this, ".ctor", null);
}
public Task<string> ReadAsStringAsync()
{
CheckDisposed();
TaskCompletionSource<string> tcs = new TaskCompletionSource<string>();
LoadIntoBufferAsync().ContinueWithStandard(task =>
{
if (HttpUtilities.HandleFaultsAndCancelation(task, tcs))
{
return;
}
if (bufferedContent.Length == 0)
{
tcs.TrySetResult(string.Empty);
return;
}
// We don't validate the Content-Encoding header: If the content was encoded, it's the caller's
// responsibility to make sure to only call ReadAsString() on already decoded content. E.g. if the
// Content-Encoding is 'gzip' the user should set HttpClientHandler.AutomaticDecompression to get a
// decoded response stream.
Encoding encoding = null;
int bomLength = -1;
byte[] data = bufferedContent.GetBuffer();
int dataLength = (int)bufferedContent.Length; // Data is the raw buffer, it may not be full.
// If we do have encoding information in the 'Content-Type' header, use that information to convert
// the content to a string.
if ((Headers.ContentType != null) && (Headers.ContentType.CharSet != null))
{
try
{
encoding = Encoding.GetEncoding(Headers.ContentType.CharSet);
}
catch (ArgumentException e)
{
tcs.TrySetException(new InvalidOperationException(SR.net_http_content_invalid_charset, e));
return;
}
}
// If no content encoding is listed in the ContentType HTTP header, or no Content-Type header present,
// then check for a byte-order-mark (BOM) in the data to figure out the encoding.
if (encoding == null)
{
byte[] preamble;
foreach(Encoding testEncoding in EncodingsWithBom)
{
preamble = testEncoding.GetPreamble();
if (ByteArrayHasPrefix(data, dataLength, preamble))
{
encoding = testEncoding;
bomLength = preamble.Length;
break;
}
}
}
// Use the default encoding if we couldn't detect one.
encoding = encoding ?? DefaultStringEncoding;
// BOM characters may be present even if a charset was specified.
if (bomLength == -1)
{
byte[] preamble = encoding.GetPreamble();
if (ByteArrayHasPrefix(data, dataLength, preamble))
bomLength = preamble.Length;
else
bomLength = 0;
}
try
{
// Drop the BOM when decoding the data.
string result = encoding.GetString(data, bomLength, dataLength - bomLength);
tcs.TrySetResult(result);
}
catch (Exception ex)
{
tcs.TrySetException(ex);
}
});
return tcs.Task;
}
public Task<byte[]> ReadAsByteArrayAsync()
{
CheckDisposed();
TaskCompletionSource<byte[]> tcs = new TaskCompletionSource<byte[]>();
LoadIntoBufferAsync().ContinueWithStandard(task =>
{
if (!HttpUtilities.HandleFaultsAndCancelation(task, tcs))
{
tcs.TrySetResult(bufferedContent.ToArray());
}
});
return tcs.Task;
}
public Task<Stream> ReadAsStreamAsync()
{
CheckDisposed();
TaskCompletionSource<Stream> tcs = new TaskCompletionSource<Stream>();
if (contentReadStream == null && IsBuffered)
{
// We cast bufferedContent.Length to 'int': The framework doesn't support arrays > int.MaxValue,
// so the length will always be in the 'int' range.
contentReadStream = new MemoryStream(bufferedContent.GetBuffer(), 0,
(int)bufferedContent.Length, false, false);
}
if (contentReadStream != null)
{
tcs.TrySetResult(contentReadStream);
return tcs.Task;
}
CreateContentReadStreamAsync().ContinueWithStandard(task =>
{
if (!HttpUtilities.HandleFaultsAndCancelation(task, tcs))
{
contentReadStream = task.Result;
tcs.TrySetResult(contentReadStream);
}
});
return tcs.Task;
}
protected abstract Task SerializeToStreamAsync(Stream stream, TransportContext context);
public Task CopyToAsync(Stream stream, TransportContext context)
{
CheckDisposed();
if (stream == null)
{
throw new ArgumentNullException("stream");
}
// The try..catch is used, since both FromAsync() and SerializeToStreamAsync() may throw: E.g. if a HWR
// gets aborted after a request is complete, but before the response stream is read, trying to read from
// the response stream will throw. Abort WebExceptions will be converted to IOExceptions by
// HttpClientHandler.WebExceptionWrapperStream.
TaskCompletionSource<object> tcs = new TaskCompletionSource<object>();
try
{
Task task = null;
if (IsBuffered)
{
task = Task.Factory.FromAsync(stream.BeginWrite, stream.EndWrite, bufferedContent.GetBuffer(), 0,
(int)bufferedContent.Length, null);
}
else
{
task = SerializeToStreamAsync(stream, context);
CheckTaskNotNull(task);
}
// If the copy operation fails, wrap the exception in an HttpRequestException() if appropriate.
task.ContinueWithStandard(copyTask =>
{
if (copyTask.IsFaulted)
{
tcs.TrySetException(GetStreamCopyException(copyTask.Exception.GetBaseException()));
}
else if (copyTask.IsCanceled)
{
tcs.TrySetCanceled();
}
else
{
tcs.TrySetResult(null);
}
});
}
catch (IOException e)
{
tcs.TrySetException(GetStreamCopyException(e));
}
catch (ObjectDisposedException e)
{
tcs.TrySetException(GetStreamCopyException(e));
}
return tcs.Task;
}
public Task CopyToAsync(Stream stream)
{
return CopyToAsync(stream, null);
}
// Workaround for HttpWebRequest synchronous resubmit
internal void CopyTo(Stream stream)
{
CopyToAsync(stream).Wait();
}
public Task LoadIntoBufferAsync()
{
return LoadIntoBufferAsync(MaxBufferSize);
}
// No "CancellationToken" parameter needed since canceling the CTS will close the connection, resulting
// in an exception being thrown while we're buffering.
// If buffering is used without a connection, it is supposed to be fast, thus no cancellation required.
public Task LoadIntoBufferAsync(long maxBufferSize)
{
CheckDisposed();
if (maxBufferSize > HttpContent.MaxBufferSize)
{
// This should only be hit when called directly; HttpClient/HttpClientHandler
// will not exceed this limit.
throw new ArgumentOutOfRangeException("maxBufferSize", maxBufferSize,
string.Format(System.Globalization.CultureInfo.InvariantCulture,
SR.net_http_content_buffersize_limit, HttpContent.MaxBufferSize));
}
if (IsBuffered)
{
// If we already buffered the content, just return a completed task.
return CreateCompletedTask();
}
TaskCompletionSource<object> tcs = new TaskCompletionSource<object>();
Exception error = null;
MemoryStream tempBuffer = CreateMemoryStream(maxBufferSize, out error);
if (tempBuffer == null)
{
// We don't throw in LoadIntoBufferAsync(): set the task as faulted and return the task.
Contract.Assert(error != null);
tcs.TrySetException(error);
}
else
{
// SerializeToStreamAsync() may throw, e.g. when trying to read from a ConnectStream where the HWR was
// aborted. Make sure to catch these exceptions and let the task fail.
try
{
Task task = SerializeToStreamAsync(tempBuffer, null);
CheckTaskNotNull(task);
task.ContinueWithStandard(copyTask =>
{
try
{
if (copyTask.IsFaulted)
{
tempBuffer.Dispose(); // Cleanup partially filled stream.
tcs.TrySetException(GetStreamCopyException(copyTask.Exception.GetBaseException()));
return;
}
if (copyTask.IsCanceled)
{
tempBuffer.Dispose(); // Cleanup partially filled stream.
tcs.TrySetCanceled();
return;
}
tempBuffer.Seek(0, SeekOrigin.Begin); // Rewind after writing data.
bufferedContent = tempBuffer;
tcs.TrySetResult(null);
}
catch (Exception e)
{
// Make sure we catch any exception, otherwise the task will catch it and throw in the finalizer.
tcs.TrySetException(e);
if (Logging.On) Logging.Exception(Logging.Http, this, "LoadIntoBufferAsync", e);
}
});
}
catch (IOException e)
{
tcs.TrySetException(GetStreamCopyException(e));
}
catch (ObjectDisposedException e)
{
tcs.TrySetException(GetStreamCopyException(e));
}
}
return tcs.Task;
}
protected virtual Task<Stream> CreateContentReadStreamAsync()
{
TaskCompletionSource<Stream> tcs = new TaskCompletionSource<Stream>();
// By default just buffer the content to a memory stream. Derived classes can override this behavior
// if there is a better way to retrieve the content as stream (e.g. byte array/string use a more efficient
// way, like wrapping a read-only MemoryStream around the bytes/string)
LoadIntoBufferAsync().ContinueWithStandard(task =>
{
if (!HttpUtilities.HandleFaultsAndCancelation(task, tcs))
{
tcs.TrySetResult(bufferedContent);
}
});
return tcs.Task;
}
// Derived types return true if they're able to compute the length. It's OK if derived types return false to
// indicate that they're not able to compute the length. The transport channel needs to decide what to do in
// that case (send chunked, buffer first, etc.).
protected internal abstract bool TryComputeLength(out long length);
private long? GetComputedOrBufferLength()
{
CheckDisposed();
if (IsBuffered)
{
return bufferedContent.Length;
}
// If we already tried to calculate the length, but the derived class returned 'false', then don't try
// again; just return null.
if (canCalculateLength)
{
long length = 0;
if (TryComputeLength(out length))
{
return length;
}
// Set flag to make sure next time we don't try to compute the length, since we know that we're unable
// to do so.
canCalculateLength = false;
}
return null;
}
private MemoryStream CreateMemoryStream(long maxBufferSize, out Exception error)
{
Contract.Ensures((Contract.Result<MemoryStream>() != null) ||
(Contract.ValueAtReturn<Exception>(out error) != null));
error = null;
// If we have a Content-Length allocate the right amount of buffer up-front. Also check whether the
// content length exceeds the max. buffer size.
long? contentLength = Headers.ContentLength;
if (contentLength != null)
{
Contract.Assert(contentLength >= 0);
if (contentLength > maxBufferSize)
{
error = new HttpRequestException(string.Format(System.Globalization.CultureInfo.InvariantCulture, SR.net_http_content_buffersize_exceeded, maxBufferSize));
return null;
}
// We can safely cast contentLength to (int) since we just checked that it is <= maxBufferSize.
return new LimitMemoryStream((int)maxBufferSize, (int)contentLength);
}
// We couldn't determine the length of the buffer. Create a memory stream with an empty buffer.
return new LimitMemoryStream((int)maxBufferSize, 0);
}
#region IDisposable Members
protected virtual void Dispose(bool disposing)
{
if (disposing && !disposed)
{
disposed = true;
if (contentReadStream != null)
{
contentReadStream.Dispose();
}
if (IsBuffered)
{
bufferedContent.Dispose();
}
}
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
#endregion
#region Helpers
private void CheckDisposed()
{
if (disposed)
{
throw new ObjectDisposedException(this.GetType().FullName);
}
}
private void CheckTaskNotNull(Task task)
{
if (task == null)
{
if (Logging.On) Logging.PrintError(Logging.Http, string.Format(System.Globalization.CultureInfo.InvariantCulture, SR.net_http_log_content_no_task_returned_copytoasync, this.GetType().FullName));
throw new InvalidOperationException(SR.net_http_content_no_task_returned);
}
}
private static Task CreateCompletedTask()
{
TaskCompletionSource<object> completed = new TaskCompletionSource<object>();
bool resultSet = completed.TrySetResult(null);
Contract.Assert(resultSet, "Can't set Task as completed.");
return completed.Task;
}
private static Exception GetStreamCopyException(Exception originalException)
{
// HttpContent derived types should throw HttpRequestExceptions if there is an error. However, since the stream
// provided by CopyTo() can also throw, we wrap such exceptions in HttpRequestException. This way custom content
// types don't have to worry about it. The goal is that users of HttpContent don't have to catch multiple
// exceptions (depending on the underlying transport), but just HttpRequestExceptions (like HWR users just catch
// WebException).
// Custom stream should throw either IOException or HttpRequestException.
// We don't want to wrap other exceptions thrown by Stream (e.g. InvalidOperationException), since we
// don't want to hide such "usage error" exceptions in HttpRequestException.
// ObjectDisposedException is also wrapped, since aborting HWR after a request is complete will result in
// the response stream being closed.
Exception result = originalException;
if ((result is IOException) || (result is ObjectDisposedException))
{
result = new HttpRequestException(SR.net_http_content_stream_copy_error, result);
}
return result;
}
private static bool ByteArrayHasPrefix(byte[] byteArray, int dataLength, byte[] prefix)
{
if (prefix == null || byteArray == null || prefix.Length > dataLength || prefix.Length == 0)
return false;
for (int i = 0; i < prefix.Length; i++)
{
if (prefix[i] != byteArray[i])
return false;
}
return true;
}
#endregion Helpers
// Built on MemoryStream which has a 31bit size limit.
private class LimitMemoryStream : MemoryStream
{
private int maxSize;
public LimitMemoryStream(int maxSize, int capacity)
: base(capacity)
{
this.maxSize = maxSize;
}
public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
{
CheckSize(count);
return base.BeginWrite(buffer, offset, count, callback, state);
}
public override void Write(byte[] buffer, int offset, int count)
{
CheckSize(count);
base.Write(buffer, offset, count);
}
public override void WriteByte(byte value)
{
CheckSize(1);
base.WriteByte(value);
}
#if !NET_4
public override Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
{
CheckSize(count);
return base.WriteAsync(buffer, offset, count, cancellationToken);
}
#endif
private void CheckSize(int countToAdd)
{
if (maxSize - Length < countToAdd)
{
throw new HttpRequestException(string.Format(System.Globalization.CultureInfo.InvariantCulture, SR.net_http_content_buffersize_exceeded, maxSize));
}
}
}
}
}