Fix for Issue 72

Sending "Expect: 100 Continue" HTTP headers to some HTTP servers generates a 417 error response.  This handles that response and tries again without sending that header.

1 files changed, 21 insertions, 0 deletions

diff --git a/src/DotNetOpenId/RelyingParty/Fetcher.cs b/src/DotNetOpenId/RelyingParty/Fetcher.cs
index 1191cb2..73d47a8 100644
--- a/src/DotNetOpenId/RelyingParty/Fetcher.cs
+++ b/src/DotNetOpenId/RelyingParty/Fetcher.cs
@@ -73,6 +73,11 @@ namespace DotNetOpenId.RelyingParty {
 		}

 

 		public static FetchResponse Request(Uri uri, byte[] body, string[] acceptTypes) {

+			return Request(uri, body, acceptTypes, false);

+		}

+

+		static FetchResponse Request(Uri uri, byte[] body, string[] acceptTypes,

+			bool avoidSendingExpect100Continue) {

 			if (uri == null) throw new ArgumentNullException("uri");

 

 			HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);

@@ -86,6 +91,17 @@ namespace DotNetOpenId.RelyingParty {
 				request.ContentType = "application/x-www-form-urlencoded";

 				request.ContentLength = body.Length;

 				request.Method = "POST";

+				if (avoidSendingExpect100Continue) {

+					// Some OpenID servers doesn't understand Expect header and send 417 error back.

+					// If this server just failed from that, we're trying again without sending the

+					// "Expect: 100-Continue" HTTP header. (see Google Code Issue 72)

+					// We don't just set Expect100Continue = !avoidSendingExpect100Continue

+					// so that future requests don't reset this and have to try twice as well.

+					// We don't want to blindly set all ServicePoints to not use the Expect header

+					// as that would be a security hole allowing any visitor to a web site change

+					// the web site's global behavior when calling that host.

+					request.ServicePoint.Expect100Continue = false;

+				}

 			}

 

 			try {

@@ -101,6 +117,11 @@ namespace DotNetOpenId.RelyingParty {
 			} catch (WebException e) {

 				using (HttpWebResponse response = (HttpWebResponse)e.Response) {

 					if (response != null) {

+						if (response.StatusCode == HttpStatusCode.ExpectationFailed) {

+							if (!avoidSendingExpect100Continue) { // must only try this once more

+								return Request(uri, body, acceptTypes, true);

+							}

+						}

 						return getResponse(uri, response);

 					} else {

 						throw;