Fix malformed Bind packets when client provides a single parameter format by rahim-kanji · Pull Request #5282 · sysown/proxysql

rahim-kanji · 2026-01-08T09:56:03Z

Background

In the PostgreSQL extended query protocol, the Bind message supports the
following semantics for parameter formats:

num_param_formats = 0: all parameters use the default text format
num_param_formats = 1: a single format applies to all parameters
num_param_formats = num_params: each parameter has an explicit format

Any other combination is invalid.

While PostgreSQL correctly applies the single provided format to all parameters,
ProxySQL previously did not replicate this behavior.

Issue

When a client sent a Bind message with:

num_param_formats = 1
num_params > 1

ProxySQL forwarded uninitialized (garbage) values for the remaining parameter
formats (libpq has a limitation where it expects a parameter format entry for each
parameter). This resulted in malformed Bind packets and protocol errors.

Fix

This PR updates ProxySQL’s Bind handling to match PostgreSQL behavior:

When exactly one parameter format is provided, ProxySQL now applies that
format to all parameters.

This prevents malformed packets and ensures compatibility with libpq and compliance with the PostgreSQL specification.

Impact

Aligns ProxySQL with PostgreSQL extended query protocol semantics
Prevents malformed Bind packets

No behavior change occurs for valid cases where all parameter formats are
explicitly provided.

Closes #5273

Summary by CodeRabbit

Bug Fixes
- Enhanced parameter format handling for PostgreSQL prepared statements, now supporting default text, single-format, and per-parameter format specifications.
Tests
- Added comprehensive regression test suite for PostgreSQL parameter format binding, covering text/binary formats, mixed formats, and NULL parameter scenarios.

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…ovided PostgreSQL allows a Bind message to specify a single parameter format (num_param_formats = 1), which applies to all parameters. libpq, however, always expects a format entry per parameter and previously sent uninitialized values for the remaining parameters when only one format was specified. This caused ProxySQL to forward malformed Bind packets to backend. ProxySQL now detects this case and propagates the single provided parameter format to all parameters, matching PostgreSQL semantics.

gemini-code-assist · 2026-01-08T09:56:21Z

Summary of Changes

Hello @rahim-kanji, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves a critical bug in ProxySQL's PostgreSQL extended query protocol implementation. It specifically addresses an issue where Bind messages specifying a single format for multiple parameters were mishandled, resulting in malformed packets and protocol errors. The changes bring ProxySQL's behavior in line with the PostgreSQL specification and improve compatibility with libpq clients, ensuring robust and correct parameter format processing.

Highlights

PostgreSQL Bind Message Protocol Alignment: ProxySQL's handling of the PostgreSQL extended query protocol's Bind message has been updated to correctly interpret cases where a single parameter format is provided for multiple parameters. Previously, this led to malformed packets and protocol errors.
Parameter Format Expansion Logic: The core fix involves modifying the PgSQL_Connection::stmt_execute_start method to expand a single provided parameter format across all parameters when num_param_formats = 1 and num_params > 1, ensuring compliance with PostgreSQL's specification.
libpq Compatibility Improvement: The PQsendQueryPrepared call now correctly passes nullptr for parameter formats when num_param_formats = 0, aligning with libpq's expectation for all-text parameters and preventing potential issues.
Comprehensive Test Coverage: New test cases have been added, including a dedicated test file pgsql-reg_test_5273_bind_parameter_format-t.cpp, to thoroughly validate the fix across various scenarios such as zero, single, and mixed parameter formats, as well as INSERT statements and NULL parameter handling.

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gemini-code-assist

Code Review

This pull request effectively addresses a bug in handling PostgreSQL Bind packets where a single parameter format was not being correctly applied to all parameters. The core logic change in PgSQL_Connection.cpp is sound and correctly implements the protocol specification by expanding the format list. The accompanying new regression test is comprehensive and covers the fix well. I have a few minor suggestions to improve code style and maintainability in both the application and test code.

lib/PgSQL_Connection.cpp

test/tap/tests/pg_lite_client.cpp

gemini-code-assist · 2026-01-08T09:58:03Z

test/tap/tests/pgsql-reg_test_5273_bind_parameter_format-t.cpp

+    test_null_parameter_handling();
+
+    return exit_status();
+}


The file does not end with a newline character. It's a common convention and good practice for text files to end with a newline to ensure compatibility with various tools and to follow POSIX standards.

Copilot

Pull request overview

This PR fixes a protocol compliance issue in ProxySQL's handling of PostgreSQL BIND messages. When a client provides a single parameter format (num_param_formats=1) for multiple parameters, ProxySQL previously forwarded uninitialized values, resulting in malformed packets. The fix ensures ProxySQL correctly expands the single format to all parameters before forwarding to libpq, which expects an explicit format for each parameter.

Adds format normalization logic in PgSQL_Connection.cpp to expand single format to all parameters
Introduces comprehensive test suite with 7 test cases covering all protocol scenarios
Adds test client helpers (bindStatementEx and bindStatementSingleFormat) for explicit format control

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
lib/PgSQL_Connection.cpp	Implements the core fix: expands single parameter format to all parameters and validates format counts
test/tap/tests/pg_lite_client.h	Adds new bind method signatures for explicit format control in tests
test/tap/tests/pg_lite_client.cpp	Implements new bind methods and updates existing bindStatement to optimize format encoding
test/tap/tests/pgsql-reg_test_5273_bind_parameter_format-t.cpp	New comprehensive test suite covering all protocol scenarios
test/tap/tests/pgsql-extended_query_protocol_test-t.cpp	Moves plan() call before cl.getEnv() for proper test structure
test/tap/tests/Makefile	Adds build target for new test

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test/tap/tests/pgsql-reg_test_5273_bind_parameter_format-t.cpp

test/tap/tests/pg_lite_client.h

test/tap/tests/pg_lite_client.cpp

test/tap/tests/pgsql-reg_test_5273_bind_parameter_format-t.cpp

sonarqubecloud · 2026-01-09T20:32:21Z

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

renecannao · 2026-01-11T21:01:11Z

@coderabbitai full review

coderabbitai · 2026-01-11T21:01:17Z

✅ Actions performed

Full review triggered.

coderabbitai · 2026-01-11T21:01:26Z

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📥 Commits

Reviewing files that changed from the base of the PR and between 4f675ed and b0ce03c.

📒 Files selected for processing (7)

lib/PgSQL_Connection.cpp
test/tap/groups/groups.json
test/tap/tests/Makefile
test/tap/tests/pg_lite_client.cpp
test/tap/tests/pg_lite_client.h
test/tap/tests/pgsql-extended_query_protocol_test-t.cpp
test/tap/tests/pgsql-reg_test_5273_bind_parameter_format-t.cpp

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rahim-kanji added 2 commits January 8, 2026 14:24

Updated pg_lite_client and Added TAP test

3f46d4a

rahim-kanji requested a review from Copilot January 8, 2026 09:56

Copilot started reviewing on behalf of rahim-kanji January 8, 2026 09:56 View session

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Copilot AI reviewed Jan 8, 2026

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rahim-kanji mentioned this pull request Jan 8, 2026

PostgreSQL extended query protocol returns "unsupported format code" #5273

Closed

Add test to groups.json

b0ce03c

renecannao added this to the Release 3.0.5 milestone Jan 11, 2026

renecannao merged commit c6ed5b9 into v3.0 Jan 12, 2026
150 of 154 checks passed

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Fix malformed Bind packets when client provides a single parameter format#5282

Fix malformed Bind packets when client provides a single parameter format#5282
renecannao merged 3 commits intov3.0from
v3.0_bind-format-issue-5273-fix

rahim-kanji commented Jan 8, 2026 •

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