public static AppFunc Middleware(AppFunc app)
{
return env =>
{
Action<Exception, Action<byte[], int, int>> showErrorMessage =
(ex, write) =>
ErrorPage(env, ex, text =>
{
var data = Encoding.ASCII.GetBytes(text);
write(data, 0, data.Length);
});
Func<Exception, Task> showErrorPage = ex =>
{
var response = new Response(env) { Status = "500 Internal Server Error", ContentType = "text/html" };
showErrorMessage(ex, response.Write);
return TaskHelpers.Completed();
};
// Don't try to modify the headers after the first write has occurred.
TriggerStream triggerStream = new TriggerStream(env.Get<Stream>(OwinConstants.ResponseBody));
env[OwinConstants.ResponseBody] = triggerStream;
bool bodyHasStarted = false;
triggerStream.OnFirstWrite = () =>
{
bodyHasStarted = true;
};
try
{
return app(env)
.Catch(errorInfo =>
{
if (!bodyHasStarted)
{
showErrorPage(errorInfo.Exception).Wait();
}
else
{
showErrorMessage(errorInfo.Exception, triggerStream.Write);
}
return errorInfo.Handled();
});
}
catch (Exception exception)
{
if (!bodyHasStarted)
{
return showErrorPage(exception);
}
else
{
showErrorMessage(exception, triggerStream.Write);
return TaskHelpers.Completed();
}
}
};
}
public Task Invoke(IDictionary<string, object> env)
{
IList<string> warnings = new List<string>();
if (!TryValidateCall(env, warnings))
{
return TaskHelpers.Completed();
}
var req = new Request(env);
Stream originalStream = req.Body;
TriggerStream triggerStream = new TriggerStream(originalStream);
req.Body = triggerStream;
// Validate response headers and values on first write.
bool responseValidated = false;
Action responseValidation = () =>
{
if (responseValidated)
{
return;
}
responseValidated = true;
if (!TryValidateResult(env, warnings))
{
return;
}
if (warnings.Count > 0)
{
req.Headers["X-OwinValidatorWarning"] = warnings.ToArray();
}
};
triggerStream.OnFirstWrite = responseValidation;
try
{
return nextApp(env)
// Run response validation explicitly in case there was no response data written.
.Then(responseValidation)
.Catch(errorInfo =>
{
SetFatalResult(env, "6.1", "An asynchronous exception was thrown from the AppFunc: <br>"
+ errorInfo.Exception.ToString().Replace(Environment.NewLine, "<br>"));
return errorInfo.Handled();
});
}
catch (Exception ex)
{
SetFatalResult(env, "6.1", "A synchronous exception was thrown from the AppFunc: <br>"
+ ex.ToString().Replace(Environment.NewLine, "<br>"));
return TaskHelpers.Completed();
}
}
public Task Invoke(IDictionary<string, object> env)
{
Request request = new Request(env);
Response response = new Response(env);
Stream orriginalStream = response.OutputStream;
TriggerStream triggerStream = new TriggerStream(orriginalStream);
response.OutputStream = triggerStream;
MemoryStream buffer = null;
triggerStream.OnFirstWrite = () =>
{
if (IsStatusWithNoNoEntityBody(response.StatusCode)
|| response.Headers.ContainsKey("Content-Length")
|| response.Headers.ContainsKey("Transfer-Encoding"))
{
return;
}
// Buffer
buffer = new MemoryStream();
triggerStream.InnerStream = buffer;
};
env[OwinConstants.ResponseBody] = triggerStream;
return nextApp(env).Then(() =>
{
if (buffer != null)
{
if (buffer.Length == 0)
{
response.Headers.SetHeader("Content-Length", "0");
}
else
{
response.Headers.SetHeader("Content-Length", buffer.Length.ToString(CultureInfo.InvariantCulture));
// Suppress the body for HEAD requests.
if (!"HEAD".Equals(request.Method, StringComparison.OrdinalIgnoreCase))
{
buffer.Seek(0, SeekOrigin.Begin);
return buffer.CopyToAsync(orriginalStream);
}
}
}
else if (!IsStatusWithNoNoEntityBody(response.StatusCode)
&& !response.Headers.ContainsKey("Content-Length")
&& !response.Headers.ContainsKey("Transfer-Encoding"))
{
// There were no Writes.
response.Headers.SetHeader("Content-Length", "0");
}
return TaskHelpers.Completed();
});
}
public Task Invoke(IDictionary<string, object> env)
{
var resp = new Response(env);
Stream orriginalStream = resp.Body;
TriggerStream triggerStream = new TriggerStream(orriginalStream);
resp.Body = triggerStream;
triggerStream.OnFirstWrite = () =>
{
var responseHeaders = resp.Headers;
if (!responseHeaders.HasHeader("Content-Type"))
{
responseHeaders.SetHeader("Content-Type", contentType);
}
};
return nextApp(env).Then(() =>
{
// Make sure this gets run even if there were no writes.
triggerStream.OnFirstWrite();
});
}
public Task Invoke(IDictionary<string, object> env)
{
Request request = new Request(env);
Response response = new Response(env);
Stream orriginalStream = response.OutputStream;
TriggerStream triggerStream = new TriggerStream(orriginalStream);
response.OutputStream = triggerStream;
FilterStream filterStream = null;
bool finalizeHeadersExecuted = false;
Action finalizeHeaders = () =>
{
finalizeHeadersExecuted = true;
if (IsStatusWithNoNoEntityBody(response.StatusCode)
|| response.Headers.ContainsKey("Content-Length")
|| response.Headers.ContainsKey("Transfer-Encoding"))
{
return;
}
// Buffer
response.Headers.SetHeader("Transfer-Encoding", "chunked");
if ("HEAD".Equals(request.Method, StringComparison.OrdinalIgnoreCase))
{
// Someone tried to write a body for a HEAD request. Suppress it.
triggerStream.InnerStream = Stream.Null;
}
else
{
filterStream = new FilterStream(orriginalStream, OnWriteFilter);
triggerStream.InnerStream = filterStream;
}
};
// Hook first write
triggerStream.OnFirstWrite = finalizeHeaders;
response.Body = triggerStream;
// Hook SendFileFunc
var sendFile = response.SendFileAsync;
if (sendFile != null)
{
response.SendFileAsync = (name, offset, count, cancel) =>
{
if (!finalizeHeadersExecuted)
{
finalizeHeaders();
}
if (filterStream == null)
{
// Due to headers we are not doing chunked, just pass through.
return sendFile(name, offset, count, cancel);
}
count = count ?? new FileInfo(name).Length - offset;
// Insert chunking around the file body
ArraySegment<byte> prefix = ChunkPrefix((uint)count);
return orriginalStream.WriteAsync(prefix.Array, prefix.Offset, prefix.Count)
.Then(() => orriginalStream.FlushAsync()) // Flush to ensure the data hits the wire before sendFile.
.Then(() => sendFile(name, offset, count, cancel))
.Then(() => orriginalStream.WriteAsync(EndOfChunk.Array, EndOfChunk.Offset, EndOfChunk.Count));
};
}
return nextApp(env).Then(() =>
{
if (!finalizeHeadersExecuted)
{
finalizeHeaders();
}
if (filterStream != null)
{
// Write the chunked terminator
return orriginalStream.WriteAsync(FinalChunk.Array, FinalChunk.Offset, FinalChunk.Count);
}
return TaskHelpers.Completed();
});
}
public Task Invoke(IDictionary<string, object> env)
{
// the first non-404 result will the the one to take effect
// any subsequent apps are not called
var iter = apps.GetEnumerator();
TaskCompletionSource<object> tcs = new TaskCompletionSource<object>();
var resp = new Response(env);
Stream outputStream = resp.Body;
Action fallback = () => { };
fallback = () =>
{
fallbackApp(env)
.Then(() => tcs.TrySetResult(null))
.Catch(errorInfo =>
{
tcs.TrySetException(errorInfo.Exception);
return errorInfo.Handled();
});
};
// Empty list
if (!iter.MoveNext())
{
fallback();
return tcs.Task;
}
Action loop = () => { };
loop = () =>
{
var threadId = Thread.CurrentThread.ManagedThreadId;
for (var tryAgainOnSameThread = true; tryAgainOnSameThread; )
{
TriggerStream triggerStream = new TriggerStream(outputStream);
triggerStream.OnFirstWrite = () =>
{
if (resp.StatusCode == 404)
{
triggerStream.InnerStream = Stream.Null;
}
};
env[OwinConstants.ResponseBody] = triggerStream;
tryAgainOnSameThread = false;
iter.Current.Invoke(env)
.Then(() =>
{
if (resp.StatusCode != 404)
{
tcs.TrySetResult(null);
return;
}
// Cleanup and try the next one.
resp.Headers.Clear();
resp.Body = outputStream;
if (iter.MoveNext())
{
// ReSharper disable AccessToModifiedClosure
if (threadId == Thread.CurrentThread.ManagedThreadId)
{
tryAgainOnSameThread = true;
}
else
{
loop();
}
// ReSharper restore AccessToModifiedClosure
}
else
{
fallback();
}
})
.Catch(errorInfo =>
{
tcs.TrySetException(errorInfo.Exception);
return errorInfo.Handled();
});
}
threadId = 0;
};
loop();
return tcs.Task;
}
