Incorrect protocol with HTTP/3

[malthert]

wp-includes/load.php

function wp_get_server_protocol:

<?php
if ( ! in_array( $protocol, array( 'HTTP/1.1', 'HTTP/2', 'HTTP/2.0' ), true ) ) {
        $protocol = 'HTTP/1.0';

Chrome Carnary already supports HTTP/3 (since a long time), so this should be fixed as it returns the incorrect protocol.

Trac ticket: https://core.trac.wordpress.org/ticket/54404#ticket

[malthert]

@johnbillion added the pull request, please merge.

[SergeyBiryukov]

Per the ​Wikipedia article on HTTP/3:

As of November 2021, the HTTP/3 protocol is still officially an Internet Draft, but is already supported by 74% of running web browsers and, according to W3Techs, 23% of the top 10 million websites. It has been supported by Google Chrome (including Chrome for Android, and Microsoft Edge, which is based on it) since April 2020 and by Mozilla Firefox since May 2021. Safari 14 (on macOS Big Sur and iOS 14) has also implemented the protocol but support is hidden behind a feature flag.

Seems like a good fit for 5.9.

[mukesh27]

PR looks good to me.

Mark as commit

[davidbaumwald]

In 52087:

Bootstrap/Load: Add HTTP/3 as a valid HTTP protocol.

As of November 2021, the HTTP/3 protocol is still officially an Internet Draft, but is already supported by 74% of running web browsers and, according to W3Techs, 23% of the top 10 million websites. It has been supported by Google Chrome (including Chrome for Android, and Microsoft Edge, which is based on it) since April 2020 and by Mozilla Firefox since May 2021. Safari 14 (on macOS Big Sur and iOS 14) has also implemented the protocol but support is hidden behind a feature flag.

Based on the wide support, this change adds HTTP/3 as a valid HTTP protocol.

Props malthert.
Fixes #54404.

Committed to core via changeset https://core.trac.wordpress.org/changeset/52087