tree eb75159b7bd936b973f94d992638b6e1ef653831
parent 89d6d17edc0f0b79f38edf6fac9e5c8bf5f3cfd7
author QUICHE team <quiche-dev@google.com> 1785874894 -0700
committer Copybara-Service <copybara-worker@google.com> 1785874931 -0700

QBONE QUIC version retry: break on region redirect.

For legacy reasons, we try QUIC version RFCv1 many times before falling back to draft29.  This is to try to drive down the # of clients using draft29, which is supposed to be deprecated.

The current code, however, runs through all QUIC versions even when a redirect occurs, which is a bit silly because a successful redirect response actually indicates the QUIC version is good.

We should immediately fail the current connection attempt so that the host can be re-resolved to the redirected region.

Implementation changes:
- Added `REDIRECT` to `QboneTunnelInterface::State` enum.
- Updated `QboneTunnel::HandleIpRangeAssignment` to return `REDIRECT` when a region redirect response is received.
- Updated `QboneTunnel::WaitForEventsUntilState` to handle `REDIRECT` as a failure state.
- Updated `QboneTunnel::ConnectIfNeeded` to break out of the QUIC version loop if the connection failed due to `REDIRECT`.
- Added integration test `OutOfRegionClientHandlesRegionFqdnRedirectWithMultipleVersions` to verify that the version loop is broken on redirect and only one connection attempt is made to the original host.

PiperOrigin-RevId: 959194912