Rewrite ODBC connection string parser to mirror msodbcsql ParseAttrStr

[saurabh500]

Summary

AB#46370

Replaces the two-phase tokenize + interpret connection-string parser in mssql-odbc/src/connection/mod.rs with a single-pass, character-by-character state machine that reproduces the shipping msodbcsql driver's ParseAttrStr (Sql/Ntdbms/sqlncli/odbc/sqlcconn.cpp) — including its quirks, so apps migrating from msodbcsql18 see identical parsing semantics.

The public signature parse_connection_string(&str) -> Result<(ConnectionParams, bool), InvalidAttrValue> is unchanged, so api/driver_connect.rs (which maps has_warnings → 01S00 and Err → connect failure) needs no change.

Reproduced msodbcsql behaviors

Quirk	Behavior
Key scan reads through ;	A token without its own = merges with following text
Missing = in remainder	S_FALSE — stop parsing, keep what was parsed
No whitespace trimming	Only leading whitespace/; before a key is skipped; Server =h no longer matches; value spaces are preserved verbatim
{braced} values	End at a single }; }} escapes a literal }
Junk after }	S_FALSE — stop (value still stored)
Unterminated {	S_FALSE — swallow rest, stop
Recognized-but-unsupported keys	No warning (full x_rgLookup set)
Unknown keywords	01S00 warning, never fail
Invalid value on validated key	E_FAIL → Err (hard connect failure)

Diagnostic mapping: S_OK → Ok((_, false)); S_FALSE → Ok((_, true)) (01S00 / SQL_SUCCESS_WITH_INFO); E_FAIL → Err(InvalidAttrValue).

Notable changes

• Expanded KNOWN_IGNORED_KEYS to msodbcsql's recognized-but-not-acted-on set (driver, dsn, app, wsid, applicationintent, multisubnetfailover, columnencryption, tnir, deprecated keys, …) so recognized keys stay silent.
• Dropped the ADO.NET/OLE DB-only aliases Initial Catalog, User Id, and Password — the msodbcsql ODBC parser does not recognize them; they are now treated as unknown keys, matching the driver.
• Deliberately not mirrored: the fixed-buffer MAXPATHLEN/MAXKEYLEN length caps (artifacts, not contract).

Tests

Exhaustive unit tests covering every quirk plus value validation, first-wins duplicates, whitespace fidelity, }} escaping, and empty/separator edge cases. 112 passed for the crate; cargo fmt --check and cargo clippy -- -D warnings are clean.

Docs

Adds mssql-odbc/docs/connection_string_parser.md documenting the algorithm, the divergence table, the state diagram, and diagnostic mapping.

Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com

[github-actions]

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[Copilot]

Pull request overview

This pull request rewrites the mssql-odbc connection-string parser to a single-pass state machine intended to mirror msodbcsql’s ParseAttrStr behavior (including documented quirks), while keeping the external parse_connection_string(&str) -> Result<(ConnectionParams, bool), InvalidAttrValue> API shape intact for the rest of the ODBC driver.

Changes:

• Replaces the previous tokenizer/interpret parser with a new state-machine implementation in a dedicated connection_string_parser module.
• Refactors connection/mod.rs into a small module hub that re-exports parse_connection_string.
• Adds documentation describing the algorithm and its msodbcsql compatibility goals.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
mssql-odbc/src/connection/mod.rs	Re-scopes the connection module and re-exports the parser from the new module.
mssql-odbc/src/connection/connection_string_parser.rs	Introduces the new single-pass, msodbcsql-compatible connection-string parser plus exhaustive unit tests.
mssql-odbc/docs/connection_string_parser.md	Adds design/behavior documentation for the parser and its msodbcsql fidelity rules.

[David-Engel]

Suggestion: the new parser-parity e2e tests build their own connection strings from cfg.Server(), cfg.Uid(), and cfg.Pwd(), but the DriverConnectLiveTest fixture only checks HasConnection(). That also allows valid e2e configurations that use ODBC_TEST_CONNSTR, DSN, or integrated auth, where those individual SQL-auth fields can be empty. In those environments these tests can fail even though the suite is configured correctly.

Could we either skip the parser-parity tests unless Server, UID, and PWD are all present, or add a small helper/fixture for tests that explicitly require mutable SQL-auth field configuration?

[saurabh500]

@ttk what's your advise on @David-Engel 's comment about e2e testing ?

[saurabh500]

Two things:

Tactical fix (in this PR, commit f457cff): added ODBCTestConfig::HasSqlAuth() (Server && UID && PWD all present) and GTEST_SKIP() at the top of the two parser-parity tests (MalformedTokenReturnsSuccessWithInfo, ConnectionStringParserParityBehaviors). They now skip cleanly in ODBC_TEST_CONNSTR, DSN, and integrated-auth environments instead of failing on an empty-credential string. Verified in WSL/unixODBC: with SQL auth the full suite is 13/13; without UID/PWD the two tests report SKIPPED (0 failures).

Proper design (follow-up #117): a capability model on the test config (enum class ODBCCap { SqlAuth, MutableDatabase, IntegratedAuth, Dsn, Encrypt } + HasCapability() + a one-line ODBC_REQUIRE_CAP(...) skip helper), plus a narrow BuildConnectionStringNarrow() so auth-neutral parser cases append to the already-configured connection rather than rebuilding it. That lets "any connection that authenticates" tests run everywhere, while tests that need mutable SQL-auth fields declare it explicitly.

@ttk and @David-Engel since I have to automate the runs of these tests in the pipeline, I have created an issue to track the management of configurations needed for various tests. For this PR I have incorporated the fix that David suggested.