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feat: verify IGMP and GRE checksums, which are parsed but never checked #2618
Description
IGMP and GRE parse their checksum field and keep it, but nothing ever checks it. Neither pcapkit/protocols/internet/igmp.py nor pcapkit/protocols/link/gre.py records a ChecksumStatus, whereas IPv4, ICMP, TCP and UDP do. Both checksums are the Internet ones' complement over the protocol's own octets, with no pseudo-header:
- IGMP: RFC 1112 and RFC 2236 cover the whole IGMP message. RFC 3376 covers the whole IGMPv3 message.
- GRE: RFC 2784, when the C bit is set, covers the GRE header and payload.
The ones' complement code that IPv4 and ICMP already use covers both, so each needs a verification hook in the same shape. pep.rst's statement that the ones' complement half is done holds only for the protocols it names. Found while #2564 re-checked pep.rst's status lines.
Activity
JarryShaw commentedon Nov 2, 2026
Blocked: the two files are already being edited by other work.
link/gre.pyis in #2614's_make_uintadoption (G2), andinternet/igmp.pyis in #2574's family-dispatch IGMP commit. This is dispatched once both land, so that the checksum hooks do not conflict with them.docs(pep): correct stale status lines and drop the redundant release …
JarryShaw commentedon Nov 2, 2026
#2629 has merged, so
link/gre.pyis free. Still blocked:internet/igmp.pyis being reworked in #2574, which also adds aversionattribute to IGMP's data model. This unblocks when #2574's PR merges.JarryShaw commentedon Nov 2, 2026
#2639 has merged as
e87eb83b1, sointernet/igmp.pyis free. Unblocked. A worker is adding the IGMP and GRE checksum checks now.JarryShaw commentedon Nov 2, 2026
The PR is #2654.
feat(protocols): verify the IGMP and GRE checksums (#2618) (#2654)