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Author SHA1 Message Date
google-labs-jules[bot]
09c3317bcf test: add unit test for setup_dir in netsleuth.reputation
Added a test case `test_refresh_netsets_setup_dir` to `tests/test_reputation.py` to ensure that the `setup_dir` nested function in `refresh_netsets` creates the required cache directory.

The test utilizes `unittest.mock.patch` to spy on `pathlib.Path.mkdir`, verifying that the function is called with `parents=True, exist_ok=True`. By setting the mock's `side_effect` to the original `mkdir` function, we ensure side-effects still execute securely, without causing issues if the test suite is run concurrently. All tests pass successfully and test coverage is extended.

Co-authored-by: Horizontal42 <75383519+Horizontal42@users.noreply.github.com>
2026-08-19 11:32:31 +00:00
Andrew Pimenov
bc8482cc99 detect PMTUD blackholes via a DF-flag binary search (--pmtud)
Stayed unprivileged on both platforms deliberately. Windows: echo_once()
gained a df: bool param setting IP_FLAG_DF on the IP_OPTION_INFORMATION
struct's Flags field (present but unused until now), and classify_status()
learned IP_PACKET_TOO_BIG (11009) - the same unprivileged IcmpSendEcho2
API the rest of the ICMP tier already uses, no new capability needed.

Unix deliberately does not hand-roll raw ICMP echo requests - unprivileged
SOCK_DGRAM/IPPROTO_ICMP checksum and identifier handling varies enough
across kernel versions that shipping it without a Linux/macOS box to
verify on felt like the wrong risk to take. Shells out to system
ping -M do -s <size> (Linux) / ping -D -s <size> (macOS/BSD) instead,
the same subprocess-and-parse pattern traceroute.py's system tiers
already use. Matches "frag"/"too long" loosely in the output rather than
an exact phrase, since a locally-cached-PMTU failure and a genuine
on-path ICMP response word themselves differently across ping
implementations - same "parse by shape" principle traceparse.py already
established.

classify_pmtu() distinguishes a path that's just narrower (a frag-needed
signal was seen - PMTUD is working, normal behind a VPN) from an actual
blackhole (large packets vanish with no ICMP reply at all - the "SSH
connects then hangs" symptom). path.pmtu_below_iface_mtu flags separately
when the path MTU is narrower than the local NIC's own MTU, which is
exactly what makes this class of problem invisible locally.

Opt-in --pmtud, excluded from --full. Live-verified on Windows against
real cloudflare.com/google.com - found the full 1500-byte MTU in 11
probes each, matching the expected binary-search depth, correct probe
history in the JSON output.

Part of plans/zesty-zooming-wilkinson.md (gitignored).
2026-08-12 23:15:59 +03:00