/// <summary>
/// Processes the incoming HTTP call and capture details about
/// the request, the response, the identity of the caller and the
/// call duration to persistent storage.
/// </summary>
/// <param name="context">A reference to the Owin context.</param>
/// <returns />
public override async Task Invoke(IOwinContext context)
{
var request = context.Request;
var response = context.Response;
// if it's an options call or tracing is not enabled, don't do anything
if (IsOptionsRequest(context) || !_options.Trace || !_options.UrlPrefixes.Any(context.Request.Uri.AbsolutePath.StartsWith))
{
await Next.Invoke(context);
return;
}
// start stopwatch to record call duration
var sw = new Stopwatch();
sw.Start();
// record call time
_options.HttpTrackingEntry.CallDateTime = DateTime.UtcNow;
// replace the request stream in order to intercept downstream reads
// Buffering mvc reponse
HttpResponse httpResponse = HttpContext.Current.Response;
StreamHelper outputCapture = new StreamHelper(httpResponse.Filter);
httpResponse.Filter = outputCapture;
// Buffering Owin response if any
IOwinResponse owinResponse = context.Response;
Stream owinResponseStream = owinResponse.Body;
owinResponse.Body = new MemoryStream();
string input = string.Empty;
var httpInputStream = HttpContext.Current?.Request?.InputStream;
if (httpInputStream.Length > 0) // can access http call
{
SetEventRequestHeaders(HttpContext.Current?.Request, _options.HttpTrackingEntry);
input = HttpUtility.UrlDecode(await new StreamReader(httpInputStream).ReadToEndAsync());
HttpContext.Current.Request.InputStream.Position = 0;
}
else
{
// owin
var requestBuffer = new MemoryStream();
var requestStream = new ContentStream(requestBuffer, request.Body);
request.Body = requestStream;
SetEventRequestHeaders(request, _options.HttpTrackingEntry);
input = HttpUtility.UrlDecode(await WriteContentAsync(requestStream, _options.HttpTrackingEntry.RequestHeaders, _maxRecordedRequestLength));
}
var anonymizedInput = _options.Anonymizer.Anonymize(input, request.Uri.ToString(), Direction.In);
// record request/input
_options.HttpTrackingEntry.Request = anonymizedInput;
// invoke next middleware
await Next.Invoke(context);
// in case owin contains response
if (outputCapture.CapturedData.Length == 0)
{
owinResponse.Body.Position = 0;
await owinResponse.Body.CopyToAsync(owinResponseStream);
}
else
{
// in case we have captured data from mvc response copy it into owinResponse
outputCapture.CapturedData.Position = 0;
outputCapture.CapturedData.CopyTo(owinResponse.Body);
}
// set response headers.
SetEventResponseHeaders(owinResponse, _options.HttpTrackingEntry);
// record call duration
sw.Stop();
var elapsed = HumanizeTimespan(sw.Elapsed);
_options.HttpTrackingEntry.CallDuration = elapsed;
// finally read final reponse body
owinResponse.Body.Seek(0, SeekOrigin.Begin);
var apiResponse = _options.Anonymizer.Anonymize(new StreamReader(owinResponse.Body).ReadToEnd(), request.Uri.ToString(), Direction.Out);
_options.HttpTrackingEntry.Response = apiResponse;
await SaveTraceAsync(_options.Context, _options.HttpTrackingEntry);
}
/// <summary>
/// Write content / request
/// </summary>
/// <param name="stream"></param>
/// <param name="headers"></param>
/// <param name="maxLength"></param>
/// <returns></returns>
private static async Task <string> WriteContentAsync(ContentStream stream, IDictionary <string, string[]> headers, long maxLength)
{
var contentType = headers.ContainsKey(ContentTypeHeader) ? headers[ContentTypeHeader][0] : null;
return(await stream.ReadContentAsync(contentType, maxLength));
}