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fix(ipv6): an extension header parsed with extension=True cannot rebuild from its own info #1446
Description
Bug. An IPv6 extension header that was parsed with extension=True does not rebuild from its own info. The layer's .data holds the rest of the datagram, but .info holds only the header, so from_data(info) returns the header alone.
Repro on main (78991b7d5), examples/captures/ipv6.pcap frame 16:
ex = next(iter(frame[IPv6]._exthdr.values())) # IPv6_Frag
len(type(ex).from_data(ex.info).data), len(ex.data) # 8, 442A hand-built HOPOPT + UDP packet behaves the same way (8 of 20 octets), so this is not specific to Fragment. The parent IPv6 layer still rebuilds exactly.
Found by the capture-driven round-trip test in #1445 (#1202), where it is listed in LAYER_GAPS.
Activity
JarryShaw commentedon Oct 9, 2026
A worker is on it now, on branch
fix/1446-ipv6-ext-header-rebuild.test: capture-driven parse→rebuild and dumper round trips (#1202)
test: capture-driven parse→rebuild and dumper round trips (#1202) (#1445
fix(ipv6)!: an extension header parsed with extension=True cannot reb…
test(roundtrip): drop the #1446 known-failure rows now that #1449 fix…