Fixes #476: Correctly handle URI which contains hostname

[jeroenvervaeke]

See detailed explanation in issue #476.

Description

This code fixes #476.

The code is now correctly handling URLs like http://example.com/favicon.ico.

Previously, because Uri::builder() .path_and_query(p) was used uri.host() would be none and path_and_query would be /http://example.com/favicon.ico.

This PR fixes that issue.
After my fix the host is now example.com and the path_and_query are /favicon.ico.

I've added the \\ normalization to fix the test_single_header and test_multiple_header unit tests.

[drcaramelsyrup]

Sorry for the delay, and thanks! It has been a known issue that the HTTP/1.1 absolute-form is not well-supported, and pingora generally assumes that we're working with the far more common origin-form.

The main issue that I see is that we really want to preserve the original form of the input uri as much as possible (the raw_path() exists as well in case the URI is not valid utf-8, but regardless aside from that we don't expect additional transformations). Is the backslash normalization required as part of using Uri::from_maybe_shared?

My other concern is that there are places in the pingora_proxy code that make the origin-form assumption, such as the way we update the h2 authority for proxying. While the origin-form doesn't seem to be breaking since the existing integration tests are passing, I wonder if the absolute-form is proxied correctly, and so it would be ideal if we could add basic proxying integration tests to h1/h2 upstreams for a client using absolute-form.

[jeroenvervaeke]

Thanks for the feedback, I'll take a look when I have some more time.

Yes, the backslash normalization is a requirement as part of using Uri::from_maybe_shared.
I've added the backslash normalization because of this test:

pingora/pingora-http/src/lib.rs

Line 686 in 758eb78

let mut req = RequestHeader::build("GET", b"\\", None).unwrap();

I'm not sure if \ should pass to be honest, I can't find it anywhere in the spec.
Is this a typo in the unit test? Or am I missing something.

In case this is a typo in the unit test we can safely get rid of the backslash normalization