[Webkit-unassigned] [Bug 219939] New: Unhandled"421 Misdirected Request" Response

bugzilla-daemon at webkit.org bugzilla-daemon at webkit.org
Wed Dec 16 01:53:51 PST 2020


https://bugs.webkit.org/show_bug.cgi?id=219939

            Bug ID: 219939
           Summary: Unhandled"421 Misdirected Request" Response
           Product: WebKit
           Version: Safari 14
          Hardware: Mac (Intel)
                OS: macOS 10.15
            Status: NEW
          Severity: Critical
          Priority: P2
         Component: Page Loading
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: joel.gaehwiler at gmail.com
                CC: beidson at apple.com

Safari 14 on macOS and iOS 14 is not handling the HTTP response code "421 Misdirected Response" for HTTP2 connections. Earlier versions, Safari 13 on macOS or iOS 13 (tested with Browserstack), do not have this issue.

If a HTTP2 connection is reused, but the host does not have the content and responds with a 421, the request will simply fail without being retried. Chrome and Firefox correctly use a fresh HTTP2 connection for that host and reach the correct server. The spec (https://tools.ietf.org/html/rfc7540#section-9.1.1) unfortunately states that this is optional, but I'm sure others depend on this as well.

Apple is actually impacted by this as well as discovered here: https://bugs.webkit.org/show_bug.cgi?id=212606. If you open https://www.icloud.com in a fresh Safari and open the Dev Console a request to https://setup.icloud.com fails due to an unhandled 421, but the page somehow recovers.

In our scenario we use a L4 SNI based proxy that routes traffic to the correct host. The whole domain space (*.cloud.shiftr.io) uses the same wildcard certificated and host address for the proxy. Now if you navigate to https://public.cloud.shiftr.io and then https://garage.cloud.shiftr.io in the *same tab* the second attempt will result in a blank page due to our backend sending a 421 with a blank page.

We will look into being less reliant on this on our end but hope to see that is fixed in Safari soon!

Enjoy the holidays!

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