Restore the previously merged macOS VPN DNS post-settle refresh,
unchanged-exemption suppression, forced pf state flush, and self-upgrade
test after they were removed by the firewall-mode merge.
Also keep Windows NRPT pointed at loopback when the listener is configured
on a wildcard address.
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.
When WFP loopback protect is active, the upstream.os healthcheck will
always fail because an external WFP block filter is interfering with
plain DNS. This demotes those expected failures to debug level and
returns errOsHealthcheckSuppressed so the recovery loop treats them
as non-fatal, eliminating the log spam described in #526.
When port 53 is taken (e.g. by mDNSResponder), ctrld failed with
'could not find available listen ip and port' instead of falling back
to port 5354. Root cause: tryUpdateListenerConfig() checked the
dnsIntercept bool, which is derived in prog.run() AFTER listener
config is resolved.
Fix: check interceptMode string directly (CLI flag + config fallback)
in a new tryUpdateListenerConfigIntercept() that tries 127.0.0.1:53
then 127.0.0.1:5354.
Also updates buildPFAnchorRules() to use the actual listener IP/port
from config instead of hardcoded 127.0.0.1:53, so pf rules redirect
to wherever ctrld is actually listening.
- Update comment in ensurePFAnchorReference: pfctl -sn returns
rdr-anchor only (nat-anchor not used by ctrld)
- Update nat-anchor table entry in pf-dns-intercept.md
- Add pf nuances 10-16 from investigation: cross-AF redirect,
block return, sendmsg EINVAL, nat-on-lo0, raw sockets, DIOCNATLOOK,
and the pragmatic IPv6 block solution
Dev Scribe