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refactor(protocols): every versioned family base dispatches on read and make (IGMP, IP, ICMP, L2TP, LinuxSLL) #2574
Description
Standing convention from the owner on #2544: on a versioned protocol family, the base class is a dispatcher on both the read and the make path. Parsing bytes through the base, or building through it (constructor or make), yields the matching member, never a base-class layer. #2544 applies it to HTTP (HTTPv1/HTTPv2) and writes it onto protocol-family-grouping.rst.
Families to bring into line, those protocol-family-grouping.rst lists with versioned members:
IGMP(IGMPv1–3). Its base is abstract today and dispatches only fromInternet._import_next_layer.IP(IPv4/IPv6).ICMP(ICMPv4/ICMPv6).L2TP(L2TPv2).LinuxSLL(LinuxSLL1/2).
For each, check what the base does now on direct construction from bytes and from fields. Make both paths yield the member, mirroring #2544's mechanism, and keep byte-exact round trips. Then test each family, and show the tests fail before the change.
Blocked: this mirrors #2544's mechanism and edits files #2542 (IGMP), #2527 (LinuxSLL) and #2544 change. It unblocks when #2544 merges; IGMP and LinuxSLL also need #2542 and #2527 merged first.
Activity
refactor(application)!: dispatch the HTTP base on read and make (#2544)
JarryShaw commentedon Nov 1, 2026
#2544 has merged. The family rollout still touches IGMP, whose names #2558 is changing, and LinuxSLL, which #2587 edits. Blocked: this unblocks when #2587 and #2558's PR merge.
JarryShaw commentedon Nov 1, 2026
Question for the rollout: does the SSL family (SSLv2, TLS, DTLS) count as a versioned family under the read-and-make dispatch rule?
TLSclass already reads every TLS version, with a fixedid()and the version in its alias, and SSLv3 is a thin subclass. SSLv2 is a separate class that TLS reaches through its fallback, andSSLdefines noread(). A dispatchingSSLbase would add a third path without fixing anything observable.SSL(...)would dispatch to SSLv2, TLS or DTLS on read and make, as the HTTP base does.fix(link): honour a stop at LinuxSLL on its ARPHRD registry path #2587 has merged. This rollout stays blocked until fix(internet): give IGMPv2 and IGMPv3 versioned names #2590 (the IGMP names) merges, so the answer can arrive any time before then.
JarryShaw commentedon Nov 2, 2026
#2587 and #2590 have merged. The final #2490 member-order reorder is now in progress, and it reorders IPv4 and IGMPv3, two of the family classes this rollout changes. Blocked: this unblocks when #2490's reorder PR merges, so that the dispatch change lands on the reordered classes rather than rebasing across them. The SSL-family question above is still open for the owner.
JarryShaw commentedon Nov 2, 2026
#2613 (the final member-order reorder) has merged, so this is unblocked. A worker is rolling read-and-make dispatch out to IGMP, IP, ICMP, L2TP and LinuxSLL, mirroring #2544's HTTP mechanism, one commit per family. It leaves SSL out, as recommended above, unless you say otherwise.
JarryShaw commentedon Nov 2, 2026
The family dispatch is done locally, one commit per family, and the Sonnet review says GOOD TO GO. Through the base, IGMP, IP and L2TP now yield their member from octets, fields and
from_data. ICMP and LinuxSLL do it from fields andfrom_data. A subclass is constructed as itself. The transport path's output and the registries matchmainexactly. It opens as a PR once the Actions queue drops below 20.Needs deciding:
ProtocolError, as HTTP refuses octets neither version takes. (b) Use the default member, which mislabels ICMPv6 and SLL2 octets. (c) Add aversion=keyword. Recommend (a), and add (c) only if a caller needs it.IP(src='::1', dst='::2')picks IPv4 and then fails. (a) Keep it names-only. (b) Also read what a shared field's value names: the address family, or the enum class oftype. Recommend (b), as a follow-up.The PR goes up implementing 1(a) and 3. If you choose otherwise, the PR changes before it merges.
4 remaining items
JarryShaw commentedon Nov 2, 2026
and I think
version=should be the source of truth and the only check to do. no need to check for version-only parameters.JarryShaw commentedon Nov 2, 2026
The owner refined answer 2, paraphrased:
version=is the source of truth and the only check made. Construction does not select a member from fields that only one member takes.version=alone picks the member, and fields withoutversion=raise.version=decides when it is given. Otherwise IGMP, IP and L2TP dispatch by the version their octets carry, and ICMP and LinuxSLL octets withoutversion=raise.from_data: unchanged.The rework in progress has been updated to match.
JarryShaw commentedon Nov 2, 2026
The rework is done locally (
wf/2574-r3, one commit per family, onfa9af520f), and a Sonnet review is running.version=alone picks it. Fields withoutversion=raise, even when a field only one member takes is passed. There is no default member.version=.version, e.g.IPv4(version=6), raises, and so does aboolversion.from_datanow goes by data-model class, as ICMP's does.from_datastill reads values, because IGMPv1 and IGMPv2 share one data model with no version field.version=that contradicts the octets fails in that member's own parser. ForIP(v6 octets, version=4)the message is a schema padding error rather than a version error.JarryShaw commentedon Nov 2, 2026
for IGMP, let's add a version attribute to their data model so to distinguish.
JarryShaw commentedon Nov 2, 2026
Owner ruling, paraphrased: IGMP's data model gains a
versionattribute that names its member.IGMP.from_datathen dispatches on that attribute, as IP and L2TP read their data's version, rather than readingtype,max_resp_timeor the length. This resolves the one exception noted above. The IGMP commit is being reworked; wire bytes and protochains stay unchanged, andinfogains aversionkey.refactor(internet): dispatch the IGMP base on read, make and from_data (
refactor(internet): dispatch the IP base on read, make and from_data (#…
refactor(internet): dispatch the ICMP base on read, make and from_data (
refactor(link): dispatch the L2TP base on read, make and from_data (#…
refactor(link): dispatch the LinuxSLL base on read, make and from_data (
docs(conventions): list each family base's dispatch in Dispatching Ba…