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fix(pcapng): epb_flags / pack_flags bits are numbered MSB-first, against the spec's LSB numbering #1273
Description
Describe the bug
BitField numbers bits MSB-first over the raw octets and ignores byte order (pcapkit/corekit/fields/strings.py:241-258), but the flags namespaces (pcapkit/protocols/schema/misc/pcapng.py:1264-1275, and the pack_flags twin) use the spec's LSB-0 numbering (direction = bits 0-1, FCS length = bits 5-8). Verified against the spec text: "bits are numbered with 0 being the least-significant bit".
To Reproduce
make(direction=INBOUND) -> 02000400 40000000 (want 01000000)
make(fcs_len=4) -> 02000400 02000000 (want 80000000)
wire flags 0x00000001 (LE) parses as direction=UNKNOWN, fcs_len=2
wire flags e5010000 -> ValueError: 3 is not a valid PacketDirection
Expected behavior
Wire 0x1 decodes as inbound; make(direction=INBOUND) writes 0x1.
Found by the misc round-trip audit (#1202). The repro was re-checked by an independent verifier, and I re-ran it on main at 11ae68ebf.
Activity
JarryShaw commentedon Oct 7, 2026
Blocked until the PCAP-NG K1-K5 PR (#1267-#1271) merges.
JarryShaw commentedon Oct 7, 2026
Unblocked: #1339 merged at 20:42Z. Back to
pending.fix(pcapng): blocks and options rebuild as parsed (#1272, #1273, #1277,
fix(pcapng): blocks and options rebuild as parsed (#1272, #1273, #1277,