2 Commits

Include renames

Author	SHA1	Message	Date
Ashin Walpola	73d4477f1e	Move the capture tooling into the repo ... live_capture.py and dump_pcap.py were untracked files inside the third-party its-g5-receiver-firmware checkout, so the tools every on-air measurement depends on were versioned nowhere and would vanish with a fresh clone of that project. They are ours rather than that project's, so they now live in capture/, with the setup notes rewritten as its README: which port the sniffer speaks on and why, how to capture, how to check a capture, and how to flash the sniffer board. live_capture.py carries the fix made on 2026-09-14. The sniffer's console converts LF to CRLF on its way out, and that applies to every 0x0a byte of the binary pcap stream, not only to log text, so every inserted CR shifts the rest of the stream. A 787 KB capture parsed cleanly for only 82 of about 2000 records, and DENMs turned up on nonsense BTP ports because their payloads carry 0x0a often. undo_crlf() reverses it on the raw stream before any framing, which is exact; afterwards a capture parsed to EOF and DENMs read as port 2002. Captures taken before that date are truncated at their first corrupted record, so anything measured from them is worth re-checking. capture/recordings/ is gitignored, since captures are data rather than source. The host tests now read both that directory and the older one in the receiver checkout, so no capture has to be moved while it is being written. dump_pcap.py reads the same console and still needs the same treatment; that is recorded in TODO.md.	2026-09-14 13:38:38 +02:00
Ashin Walpola	75d6d3b85c	Receive signed ITS messages and forward each at its declared length ... Signed packets. A GeoNetworking Basic Header NextHeader of 2 means a TS 103 097 (IEEE 1609.2) envelope follows, with the Common Header inside it. gn_unwrap_its rejected all of these, and most real traffic is signed: the 2026-08-17 capture holds 157 signed frames from 15 source MACs against 2 unsecured stations. It now opens a COER-encoded signedData, or a bare unsecuredData, and parses the inner packet as before. The inner packet comes first inside tbsData, so the certificate and signature are never parsed, and the signature is not verified - the firmware has no trust store. Such messages reach the phone with the new V2X_RX flags bit1, signed but not verified. The app reads only bit0 and is unaffected until it learns the flag. Encrypted payloads, nested signing and the legacy v1.2.1 envelope are still rejected. All 157 recorded signed frames have the layout this reads, in all three COER length forms, and asn1tools decodes every envelope to the same inner packet. Payload bounds. Every frame recorded through the ESP32-C5's promiscuous RX, about 15 000 of them, ends in 8 bytes that are not part of the 802.11 frame and not a valid FCS. obu-firmware reads frames through the same API and took the rest of the frame as the message, so it forwarded those 8 bytes to the phone after every message. UPER decoders stop where the message ends, so nothing visibly broke, but the bytes cost serial bandwidth and 8 bytes of the DENM's headroom, and they stayed attached wherever raw payloads were stored or passed on. The payload is now exactly what the Common Header's payload-length field declares, which is also what separates a signed message from its signature. A frame longer than main.c's 800-byte capture buffer is now reported as truncated instead of being forwarded cut off, and counted as an oversize drop through the new serial_link_note_oversize_drop, as it was when the cut-off frame failed serial_link's size check. Host tests in obu-firmware/test/host build the firmware sources unmodified with MSYS2 gcc; `make` runs all three. - test_chain: frames from the firmware's TX code checked byte by byte against EN 302 636-4-1 and parsed back, including hand-built signed frames, the payload-length rule, the RX trailer, and every truncation length against a no-access guard page. 1731 checks, 0 failures. - test_replay and check_replay.py: all 15 145 recorded frames through gn_unwrap_its, cut to 800 bytes as on the board, and re-derived independently in Python with the envelope decoded by asn1tools. They agree on every record; 15 131 accepted, 157 of them signed. 11 043 of the 11 106 distinct messages re-encode byte-identically. The other 63 fail the same way with the old 8 bytes put back, so the boundary is not the cause: 5 are our own CAMs from before the 2026-08-20 yawRateConfidence fix, and the rest, from other stations, are a follow-up in TODO.md. - fuzz_gn_unwrap: random edits of every recorded frame, each run against the guard page. 50 000 000 iterations, no crash. obu-firmware/test/pcap_gn_tally.py tallies GeoNetworking header fields per station over captures; it is how the other stations' lifetimes were measured. TODO.md collects what is still open, including the on-air check for this change: it builds on IDF 6.1 but has not been flashed.	2026-09-11 20:19:40 +02:00