When IPv6 is available locally but the selected IPv6 DoH endpoint is
unroutable (e.g. dialing [2606:1a40::22]:443 returns "no route to host"
while IPv4 stays usable), ctrld re-bootstrapped and re-dialed the endpoint
every ~2s. A weekend soak produced ~46.7k "no route to host" lines, with
the dial/health-check loop dominating the log during bad windows.
Add bounded backoff/suppression for network-unreachable endpoints at two
levels:
- ParallelDialer (internal/net): track dial addresses that fail with
ENETUNREACH/EHOSTUNREACH and skip them for an exponentially growing,
bounded window (5s -> 60s). A successful dial clears the entry
immediately, so recovery is preserved when the route returns. When every
candidate is suppressed the dial fails fast and quietly instead of
hammering known-unroutable addresses.
- Upstream recovery loop (cmd/cli): demote unreachable check failures to
debug and back off the retry cadence (2s -> 60s) for an unreachable
streak; any other failure resets to the base cadence.
The new IsUnreachable classifier lives in internal/net and is reused by
cmd/cli's errNetworkError, so the unreachable-errno matching has a single
definition. Note the explicit winsock constants (10051/10065) are required
on Windows: syscall.ENETUNREACH/EHOSTUNREACH are Go's portable "invented"
values and never equal the raw WSA codes a failing connect surfaces.
Suppression and backoff are always bounded, so IPv6 is never disabled until
restart and recovers on its own once the route is back. Split-stack
selection and the #549 macOS intercept recovery work are untouched.
Adds unit tests for the classifier, the dialer's suppression tracker, and
the recovery backoff schedule.
The test:windows CI job intermittently failed to clean up .testbin with
"Access to the path '...cmd_cli.test.exe' is denied". This was previously
attributed to Windows Defender scanning the large unsigned test binaries,
and mitigated with Defender exclusions and cleanup retries. That was
treating a symptom.
Root cause: performUpgrade() self-upgrades by running
exec.Command(os.Executable(), "upgrade", "prod", "-vv") as a detached,
windowless child. In the real ctrld binary this re-execs ctrld and is
correct. Under `go test`, os.Executable() is the test binary itself, and
`go test` stops flag parsing at the first positional arg ("upgrade") and
ignores the rest -- so the child silently re-runs the entire test suite.
That child hits the upgrade tests again and spawns more detached children,
recursively: a fork bomb of hidden processes that pins the runner's
CPU/memory and keeps the test binary's image file locked. Windows refuses
to delete the image of a running process, hence the "Access is denied"
during after_script. Whether any children are still alive when cleanup
runs is a timing race, which is why the failure was flaky.
Two tests reached this path: Test_performUpgrade (directly) and
Test_selfUpgradeCheck (via selfUpgradeCheck -> performUpgrade on the
"upgrade allowed" case).
Fix:
- prog.go: extract the command construction into a package-level
newUpgradeCmd var. Production behavior is unchanged.
- main_test.go: stub newUpgradeCmd once in TestMain so the whole test
binary self-execs with `-test.run=^$` (matches no tests, exits
immediately) instead of re-running the suite. This covers every test
that reaches performUpgrade, present and future, while still exercising
the cmd.Start() success path.
- Move version checking logic to shouldUpgrade for testability
- Move upgrade command execution to performUpgrade
- selfUpgradeCheck now composes these two for clarity
- Update and expand tests: focus on logic, not side effects
- Improves maintainability, testability, and separation of concerns
Cuong Manh Le