fix: accept uppercase .local. trailer in service_type_name by bluetoothbot · Pull Request #1747 · python-zeroconf/python-zeroconf

bluetoothbot · 2026-05-20T11:46:14Z

Summary

DNS name comparisons are case-insensitive (RFC 1035 §2.3.3, RFC 6762 §16), but service_type_name rejected inputs whose .local. / ._tcp.local. / ._udp.local. trailer used any non-lowercase letter (e.g. Localhost.LOCAL.). This change normalises the input case for the trailer match only; the returned trailer still preserves the caller's original casing so existing type_.endswith(service_type_name(name)) checks in ServiceInfo keep working.

Fixes #1746

Changes

_utils/name.py: compare type_.lower() against the trailer constants in both the strict (._tcp.local. / ._udp.local.) and non-strict (.local.) branches.
tests/utils/test_name.py: cover mixed-case strict trailers and the issue's reported Localhost.LOCAL. non-strict case.

Test plan

poetry run pytest tests/utils/test_name.py -v — new mixed-case cases pass.
Full pure-Python suite (SKIP_CYTHON=1 poetry run pytest --timeout=60) — 372 passed, 2 skipped, no regressions.
poetry run ruff check / ruff format --check on touched files.

Generated by Kōan /fix

Quality Report

Changes: 2 files changed, 23 insertions(+), 2 deletions(-)

Code scan: clean

Tests: passed (4 PASSED)

Branch hygiene: clean

Generated by Kōan post-mission quality pipeline

DNS name comparisons are case-insensitive (RFC 1035 §2.3.3, RFC 6762 §16), so service_type_name should accept names such as "Localhost.LOCAL." or "_http._TCP.local." instead of rejecting them with BadTypeInNameException. Lowercase the input only for the endswith checks; the returned trailer still preserves the caller's original casing, so ServiceInfo's existing "type_.endswith(service_type_name(name))" check keeps working when both sides share the same case.

codspeed-hq · 2026-05-20T11:48:11Z

Merging this PR will not alter performance

✅ 14 untouched benchmarks

_{Comparing bluetoothbot:koan/fix-issue-1746 (0b2c539) with master (0e201f7)}

codecov · 2026-05-20T11:48:36Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.76%. Comparing base (0e201f7) to head (0b2c539).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1747   +/-   ##
=======================================
  Coverage   99.76%   99.76%           
=======================================
  Files          33       33           
  Lines        3455     3456    +1     
  Branches      478      478           
=======================================
+ Hits         3447     3448    +1     
  Misses          5        5           
  Partials        3        3

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Copilot

Pull request overview

Updates service_type_name() to treat the .local. / ._tcp.local. / ._udp.local. trailer as case-insensitive (per DNS rules) while preserving the caller’s original casing in the returned trailer, fixing mixed-case .LOCAL. inputs.

Changes:

Normalize the input to type_.lower() for trailer matching in both strict and non-strict parsing branches.
Add tests covering mixed-case strict trailers and the reported Localhost.LOCAL. non-strict case.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
`src/zeroconf/_utils/name.py`	Makes trailer detection case-insensitive by comparing against constants using a lowercased view of the input.
`tests/utils/test_name.py`	Adds regression tests for mixed-case `.LOCAL.` trailer handling in strict and non-strict modes.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

+        ("_http._tcp.LOCAL.", "_http._tcp.LOCAL."),
+        ("_http._TCP.local.", "_http._TCP.local."),
+        ("_HTTP._tcp.local.", "_HTTP._tcp.local."),
+        ("Instance._http._tcp.LOCAL.", "_http._tcp.LOCAL."),


bdraco · 2026-05-20T12:02:26Z

@bluetoothbot rr

bluetoothbot · 2026-05-20T12:05:20Z

PR Review — fix: accept uppercase .local. trailer in service_type_name

Tight, well-scoped fix. Lowering type_ only for the endswith comparison while keeping type_ itself for slicing/returning preserves the caller's original casing — that matters because downstream callers in ServiceInfo do type_.endswith(service_type_name(name)), and lowercasing the returned trailer would silently break them. The PR description calls this out, and the test for Localhost.LOCAL. -> LOCAL. pins that contract. Slice math is unaffected by case since _TCP_PROTOCOL_LOCAL_TRAILER and _NONTCP_PROTOCOL_LOCAL_TRAILER are the same length, so the shared len(_TCP_PROTOCOL_LOCAL_TRAILER) slice in the strict branch remains correct for _udp inputs. Only nit: parametrized strict coverage is _tcp-only — adding one _udp mixed-case row would harden the second tuple member against future refactors. Not a blocker; merge-ready.

🟢 Suggestions

1. Add a `_udp` mixed-case case to cover the second trailer constant (`tests/utils/test_name.py`, L64-71)

The implementation matches against the tuple (_TCP_PROTOCOL_LOCAL_TRAILER, _NONTCP_PROTOCOL_LOCAL_TRAILER) in a single endswith call, but every parametrized strict case here is _tcp. The _udp branch passes today only because the lowering is identical for both — but if someone later refactors that endswith into two separate branches (e.g. to error-message which trailer was matched), a _udp regression won't be caught. Adding one mixed-case _udp case (e.g. ('_printer._UDP.local.', '_printer._UDP.local.') or '_printer._udp.LOCAL.') pins both halves of the tuple. This is the same point Copilot raised inline at line 70.

("_http._tcp.LOCAL.", "_http._tcp.LOCAL."),
("_http._TCP.local.", "_http._TCP.local."),
("_HTTP._tcp.local.", "_HTTP._tcp.local."),
("Instance._http._tcp.LOCAL.", "_http._tcp.LOCAL."),

Checklist

Trailer constants are lowercase, so lower() comparison is sound
Returned trailer preserves caller casing (backward compat with endswith(service_type_name(...)) callers)
Slice arithmetic correct for both _tcp and _udp after case normalization
RFC citation present in code comment and commit (RFC 1035 §2.3.3 / RFC 6762 §16)
Edge case coverage: mixed-case _udp trailer — suggestion ＃1
No untested branches introduced (codecov reports 100% on changed lines)

Summary

Tight, well-scoped fix. Lowering type_ only for the endswith comparison while keeping type_ itself for slicing/returning preserves the caller's original casing — that matters because downstream callers in ServiceInfo do type_.endswith(service_type_name(name)), and lowercasing the returned trailer would silently break them. The PR description calls this out, and the test for Localhost.LOCAL. -> LOCAL. pins that contract. Slice math is unaffected by case since _TCP_PROTOCOL_LOCAL_TRAILER and _NONTCP_PROTOCOL_LOCAL_TRAILER are the same length, so the shared len(_TCP_PROTOCOL_LOCAL_TRAILER) slice in the strict branch remains correct for _udp inputs. Only nit: parametrized strict coverage is _tcp-only — adding one _udp mixed-case row would harden the second tuple member against future refactors. Not a blocker; merge-ready.

Automated review by Kōan8b1fc34

bluetoothbot · 2026-05-20T12:06:45Z

Rebase with requested adjustments

Branch koan/fix-issue-1746 was rebased onto master and review feedback was applied.

Changes applied

Added _udp mixed-case cases per Copilot review.
Added three _udp parametrized cases to test_service_type_name_uppercase_trailer: uppercase .LOCAL. trailer, uppercase _UDP proto label, and instance-prefixed uppercase trailer. Covers _NONTCP_PROTOCOL_LOCAL_TRAILER path per Copilot reviewer request at tests/utils/test_name.py:70.

Stats

2 files changed, 26 insertions(+), 2 deletions(-)

Actions performed

Already-solved check: negative (confidence=high, reasoning=No recent master commit touches service_type_name case-insensitivity; trailer comparison still uses )
Rebased koan/fix-issue-1746 onto upstream/master
Applied review feedback
Pre-push CI check: previous run passed
Force-pushed koan/fix-issue-1746 to origin
CI check enqueued in ## CI (async)

CI status

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Automated by Kōan

bluetoothbot temporarily deployed to release May 20, 2026 11:51 — with GitHub Actions Inactive

bdraco requested a review from Copilot May 20, 2026 11:56

Copilot started reviewing on behalf of bdraco May 20, 2026 11:56 View session

Copilot AI reviewed May 20, 2026

View reviewed changes

Comment thread tests/utils/test_name.py

("_http._tcp.LOCAL.", "_http._tcp.LOCAL."),

("_http._TCP.local.", "_http._TCP.local."),

("_HTTP._tcp.local.", "_HTTP._tcp.local."),

("Instance._http._tcp.LOCAL.", "_http._tcp.LOCAL."),

test: cover mixed-case _udp trailer in service_type_name

0b2c539

bluetoothbot temporarily deployed to release May 20, 2026 12:10 — with GitHub Actions Inactive

bdraco marked this pull request as ready for review May 20, 2026 12:15

bdraco approved these changes May 20, 2026

View reviewed changes

bdraco merged commit 37edde2 into python-zeroconf:master May 20, 2026
36 checks passed

bluetoothbot deleted the koan/fix-issue-1746 branch May 20, 2026 12:23

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fix: accept uppercase .local. trailer in service_type_name#1747

fix: accept uppercase .local. trailer in service_type_name#1747
bdraco merged 2 commits into
python-zeroconf:masterfrom
bluetoothbot:koan/fix-issue-1746

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Pull request overview

Reviewed changes

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bdraco commented May 20, 2026

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bluetoothbot commented May 20, 2026

PR Review — fix: accept uppercase .local. trailer in service_type_name

🟢 Suggestions

Checklist

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bluetoothbot commented May 20, 2026

Rebase with requested adjustments

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bluetoothbot commented May 20, 2026 •

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