refactor: rename remaining BIP14 subversion identifiers to user agent

l0rinc commented at 1:24 pm on January 29, 2026: contributor

Problem

BIP14 defines the sub_version_num field in version messages as a user-agent string, but there are still internal and user-facing references to “subver/subversion” (as noted in #34389 (review)).

Fix

The first commit performs the bulk of the mechanical work via a scripted-diff that (with a leading preflight check to make sure the target names don’t collide), renaming internal identifiers from *SubVersion*/subver* to *UserAgent*/user_agent. I have verified the mechanical renames via to produce the same binary (except for the test_FormatSubVersion unit test name).

The second commit follows up with the remaining non-mechanical cleanup, adjusting user-facing descriptions, comments, and local variable names to use “user agent” and explicitly referencing BIP14 as justification.

For compatibility, the RPC keys (subver, subversion) are intentionally left unchanged.

scripted-diff: rename subversion identifiers to user agent

BIP14 specifies that the `sub_version_num` field is a user agent string.
A few values can safely be renamed automatically.

-BEGIN VERIFY SCRIPT-
git grep -qE 'FormatUserAgent|formatUserAgent|strUserAgent|MAX_USER_AGENT_LENGTH|cleanUserAgent|m_user_agent_mutex|USER_AGENT_COLUMN_WIDTH|P2P_USER_AGENT' -- src test/functional && echo "Error: Target identifiers already exist in src/ or test/functional" && exit 1

git grep -lE 'FormatSubVersion|formatSubVersion|strSubVersion|MAX_SUBVERSION_LENGTH|cleanSubVer|m_subver_mutex|SUBVERSION_COLUMN_WIDTH|P2P_SUBVERSION|strSubVer|Subversion' -- src test/functional | \
  xargs sed --in-place \
    -e 's/FormatSubVersion/FormatUserAgent/g' \
    -e 's/formatSubVersion/formatUserAgent/g' \
    -e 's/strSubVersion/strUserAgent/g' \
    -e 's/MAX_SUBVERSION_LENGTH/MAX_USER_AGENT_LENGTH/g' \
    -e 's/cleanSubVer/cleanUserAgent/g' \
    -e 's/m_subver_mutex/m_user_agent_mutex/g' \
    -e 's/SUBVERSION_COLUMN_WIDTH/USER_AGENT_COLUMN_WIDTH/g' \
    -e 's/P2P_SUBVERSION/P2P_USER_AGENT/g' \
    -e 's/strSubVer/user_agent/g' \
    -e 's/Subversion/UserAgent/g'
-END VERIFY SCRIPT-

7d59e5379b

doc,rpc,test: refer to BIP14 user agent

BIP14 specifies that the `sub_version_num` field is a user agent string.
Update user-facing text, comments, and local variable names accordingly, while keeping RPC keys ("subver", "subversion") unchanged for compatibility.

5636c68453

DrahtBot commented at 1:25 pm on January 29, 2026: contributor

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Reviews

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Type	Reviewers
Concept NACK	ajtowns
Concept ACK	naiyoma

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Conflicts

Reviewers, this pull request conflicts with the following ones:

#34389 (net/log: standardize peer+addr log formatting via LogPeer by l0rinc)
#34293 (Bugfix: net_processing: Restore missing comma between peer and peeraddr in “receive version message” and “New ___ peer connected” by luke-jr)
#34181 (refactor: [p2p] Make ProcessMessage private again, Use references when non-null by maflcko)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

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Possible places where named args for integral literals may be used (e.g. func(x, /*named_arg=*/0) in C++, and func(x, named_arg=0) in Python):

check_bytesrecv(peer, msg_type, min_bytes_recv) in test/functional/test_framework/test_framework.py

2026-01-29 13:25:27

l0rinc renamed this:
~~refactor/BIP14: rename remaining subversion identifiers to user agent~~
refactor: rename remaining BIP14 subversion identifiers to user agent
on Jan 29, 2026

DrahtBot added the label Refactoring on Jan 29, 2026

naiyoma commented at 7:50 pm on February 6, 2026: contributor

Concept ACK

Changes align with proposal:-> https://github.com/bitcoin/bips/blob/master/bip-0014.mediawiki#proposal

“The currently unused sub_version_num field in "version" packets will become the new user-agent string.”

I grepped twice to check on the remaining instance git grep -i "subver" -- src test/functional git grep -i "subver" -- ':!src' ':!test/functional

Other than the RPC keys. These changes also do not touch the release notes and doc/bips.md, which should be left as-is.

ajtowns commented at 9:19 pm on February 6, 2026: contributor

Concept NACK. This touches 28 files for a purely cosmetic rename — the merge conflict cost (already 3 conflicting PRs) and git blame churn outweigh the naming consistency benefit IMO.

The internal terminology has been “subversion” for 15 years and is well-understood by anyone working on this code. BIP 14 defined how we format the string, and introduced the separation between protocol and client version, but I don’t think it obligates us to match its naming internally. (Personally, I think “subversion” is a nice string to have peppered through our codebase anyway)

If the concern is that bips.md’s description feels inaccurate, note that the entry already has a bug: it cites #669 (multisig/OP_EVAL) but the actual BIP 14 implementation was #707.

(** Using AI to edit my NACKs to make them less mean)

l0rinc commented at 9:28 pm on February 6, 2026: contributor

Thanks for the feedback.

l0rinc closed this on Feb 6, 2026

refactor: rename remaining BIP14 subversion identifiers to user agent #34444

Problem

Fix

Reviews

Conflicts

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