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The handshake carries a one-byte collation ID, so the collations map only holds IDs below 256. With charset set, the collation is applied after auth by SET NAMES <charset> COLLATE <collation>, so newer collations work there (see #1665). Since #1604, the handshake returns unknown collation only when a charset is set, the opposite of the comment on that branch. So the #1603 DSN charset=utf8mb4&collation=utf8mb4_0900_as_ci and Charset("utf8mb4", "utf8mb4_0900_bin") still fail with unknown collation, while collation=utf8mb4_0900_as_ci alone connects and silently uses utf8mb4_general_ci.
This flips the condition. With a charset, an unknown collation now sends the default ID and SET NAMES sets the real one. Without a charset, an unknown collation fails at connect again, as in v1.8.1. For example, collation=utf8mb4_uca1400_ai_ci without charset on MariaDB 11 will now fail; adding charset=utf8mb4 fixes it. If you'd rather keep collation-only lenient, I can drop the error branch instead so only #1603 is fixed.
Ran:
go test -count=1 -run TestHandshakeCollation -v .: on master, unknown with charset and unknown fail; with this change all 5 cases pass.
go test -count=1 ./...: ok (server-dependent tests skip without a MySQL server).
go vet ./..., gofmt -l, staticcheck v0.7.0: no findings.
Checklist
Code compiles correctly
Created tests which fail without the change (if possible)
All tests passing
Extended the README / documentation, if necessary
Added myself / the copyright holder to the AUTHORS file
The handshake only carries a one-byte collation ID. A collation that is
not in the collations map can still be used when a charset is set,
because it is applied afterwards with SET NAMES <charset> COLLATE
<collation>. The check was inverted: it rejected exactly that case and
silently ignored unknown collations when no charset was set.
The handshake response now checks unknown collations when no charsets are configured. Tests cover default and known collation IDs, plus unknown collation behavior. The AUTHORS list adds Ngo Quoc Viet and an email address.
Changes
Handshake Collation Handling
Layer / File(s)
Summary
Collation handling and tests packets.go, packets_test.go
The handshake response checks unknown collations when no charsets are configured. Tests cover known collation IDs and the unknown-collation error or fallback behavior.
Author Entry
Layer / File(s)
Summary
Add author entry AUTHORS
The AUTHORS list adds Ngo Quoc Viet and an email address.
Validate collation names before merging to prevent SQL syntax in connection configuration from becoming an additional database statement. The risk is limited to applications that allow such configuration input and enable multiple statements.
Pre-merge checks: 5
Check name
Status
Explanation
Title check
The title clearly and concisely identifies the main change: correcting the inverted unknown-collation check in packets handling.
Description check
The description directly explains the collation-handling change, its intended behavior with and without a charset, test coverage, and validation results.
Docstring Coverage
Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 2 files. (1 skipped: 1 …
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Full details: Docstring Coverage
Explanation
Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 2 files. (1 skipped: 1 unsupported.)
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Actionable comments posted: 1
🪄 Fix comments: Fix CodeRabbit comments on this PR
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Inline comments:
Review comments at @packets.go:
- Around line 345-347: In the collation handling branch that checks
mc.cfg.charsets and uses cname, validate unmapped collation names before they
can reach SET NAMES; reject names containing characters outside the allowed
alphanumeric and underscore set. Preserve the existing handling for mapped
collations and for configurations without a charset.
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AUTHORS
packets.go
packets_test.go
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Description
The handshake carries a one-byte collation ID, so the
collationsmap only holds IDs below 256. Withcharsetset, the collation is applied after auth bySET NAMES <charset> COLLATE <collation>, so newer collations work there (see #1665). Since #1604, the handshake returnsunknown collationonly when a charset is set, the opposite of the comment on that branch. So the #1603 DSNcharset=utf8mb4&collation=utf8mb4_0900_as_ciandCharset("utf8mb4", "utf8mb4_0900_bin")still fail withunknown collation, whilecollation=utf8mb4_0900_as_cialone connects and silently uses utf8mb4_general_ci.This flips the condition. With a charset, an unknown collation now sends the default ID and
SET NAMESsets the real one. Without a charset, an unknown collation fails at connect again, as in v1.8.1. For example,collation=utf8mb4_uca1400_ai_ciwithoutcharseton MariaDB 11 will now fail; addingcharset=utf8mb4fixes it. If you'd rather keep collation-only lenient, I can drop the error branch instead so only #1603 is fixed.Ran:
go test -count=1 -run TestHandshakeCollation -v .: on master,unknown with charsetandunknownfail; with this change all 5 cases pass.go test -count=1 ./...: ok (server-dependent tests skip without a MySQL server).go vet ./...,gofmt -l, staticcheck v0.7.0: no findings.Checklist