Real-device testing showed the previous retry-based fix (ad30f93) was
insufficient: a bare ioctl(TUNSETIFF)-created tap device (no IFF_PERSIST)
could work for one command and then vanish for the next on that kernel,
not just be slow to appear. Both tap devices are now created ahead of
time via an external `ip tuntap add dev <name> mode tap` before being
attached to via open_tap(), making them genuine persistent netdevices
with no tie to any fd/process lifetime -- the same technique QEMU/libvirt
use. stop_tap_relay() now explicitly `ip link del`s the host-side device
since it no longer disappears on its own; the crash-orphan sweep records
each relay's network kind/name too so it can do the same for orphans.
All retry logic (network_join.cpp's run_with_retry(), self_test.cpp's
wait_for_container_device_visible()) is removed as no longer needed.
self_test.cpp's post-teardown assertions updated to match: the host-side
device is now expected gone after stop_tap_relay(), while the
container-side device is expected to persist (it only goes away once its
own namespace is torn down, not merely because the relay stopped).
Verified end-to-end on the dev machine with --no-veth forcing the
fallback: eth0 stayed visible and usable across repeated commands with
no disappearance, and both gateway and outside (8.8.8.8) ping succeeded
at 0% loss.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Gv3s5jckJKzh6JkMoi2Akz
ceamac
bebf559039