If the server received the new code point, while it doesn't support, the ALPS extension will ignore. This also mean client might not know the server's client hints preferences before the first request. Currently, only few sites using the ALPS extension. As TLS extension is negotiated, the server need to support both code points during the transition period, after some time, the server can drop the old one.
On Wednesday, January 17, 2024 at 11:00:13 AM UTC-5 Yoav Weiss wrote: > On Saturday, January 13, 2024 at 12:08:33 AM UTC+1 Victor Tan wrote: > > Contact emails > > victor...@chromium.org, miketa...@chromium.org, david...@chromium.org > > Explainer > > https://github.com/WICG/client-hints-infrastructure/ > blob/main/reliability.md > > Specification > > https://tools.ietf.org/html/draft-davidben-http-client-hint-reliability > > https://tools.ietf.org/html/draft-vvv-httpbis-alps > > https://tools.ietf.org/html/draft-vvv-tls-alps > > > Summary > > Shipping a new code point (17613) for TLS ALPS extension to allow adding > more data in the ACCEPT_CH HTTP/2 and HTTP/3 frame. The ACCEPT_CH HTTP/2 > frame with the existing TLS ALPS extension code point (17513) had an > arithmetic overflow bug <https://crbug.com/1292069> in the Chrome ALPS > decoder. It limits the capability to add more than 128 bytes data (in > theory, the problem range is 128 bytes to 255 bytes) to the ACCEPT_CH > frame. With the new ALPS code point, we can fully mitigate the issue. > > Blink component > > Blink>Network>ClientHints > <https://bugs.chromium.org/p/chromium/issues/list?q=component%3ABlink%3ENetwork%3EClientHints%2C&can=2> > > TAG review > > https://github.com/w3ctag/design-reviews/issues/549 > > TAG review status > > Closed > > Risks > Interoperability and Compatibility > > This is switching to a new code point for the TLS ALPS extension. It won’t > change the design of ALPS and ACCEPT_CH mechanism implementation. The main > source of compatibility risk is that it causes conflicts with ALPS > negotiation since some clients could still use the old code point while > others are switching to use the new code point. The ALPS extension could > be ignored if the code point doesn’t match during negotiation, which means > the server's client hints preferences won’t be delivered in the ACCEPT_CH > HTTP/2 and HTTP/3 frame. We mitigate this by enabling servers to support > both code points, monitoring both code points usage and removing the old > ALPS code point support in a future intent once the usage is low enough. We > also split the rollout into two phases: we first start to enable the new > ALPS code point for ACCEPT_CH with HTTP/3 frame in a slow rollout, and > then eventually enable the new code point with HTTP/2 frame. > > > Does the server have an indication if the client in question supports the > newer code point? > If not, what would we expect servers that support the newer code point to > do? > > > > > Edge: No signals > > Firefox: Pending https://github.com/mozilla/standards-positions/issues/510 > Safari: Pending https://lists.webkit.org/pipermail/webkit-dev/2021- > April/031768.html > > Web/Framework developers: https://twitter.com/Sawtaytoes/status/ > 1369031447940526080 https://twitter.com/_jayphelps/status/ > 1369023028735148032 > > Activation > > The site’s TLS and HTTP serving application would need to be updated to > support this new code point. We aren’t aware of many sites using this > feature yet, however. > > Debuggability > > No special DevTools support needed. The effects of the code point change > of ACCEPT_CH frame will be visible in the DevTools’ network tab. Also, the > NetLog will record the ACCEPT_CH frame value if TLS ALPS extension is > negotiated successfully. > > Will this feature be supported on all six Blink platforms (Windows, Mac, > Linux, Chrome OS, Android, and Android WebView)? > > Yes > > Is this feature fully tested by web-platform-tests > <https://chromium.googlesource.com/chromium/src/+/master/docs/testing/web_platform_tests.md> > ? > > No, this feature is tested with browser-side tests. We can’t test > TLS-adjacent features currently through web-platform-tests. See this issue: > https://github.com/web-platform-tests/wpt/issues/20159 > > Flag name > > UseNewAlpsCodepointHttp2 > > UseNewAlpsCodepointQUIC > > Tracking bug > > b/289087287 > > Launch bug > > https://launch.corp.google.com/launch/4299022 > > Link to entry on the Chrome Platform Status > https://chromestatus.com/feature/5149147365900288 > > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to blink-dev+unsubscr...@chromium.org. To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/1d4cd923-5487-4cdf-a167-4da7b6a0a84cn%40chromium.org.
