Security and modernization improvements

[renechoi]

Overview

This pull request addresses two critical issues identified during a comprehensive security and modernization audit of the QueryDSL codebase:

1. Hardcoded Database Credentials: Test connection classes contained hardcoded usernames and passwords.
2. Deprecated Reflection API: The codebase used Class.newInstance(), which has been deprecated since Java 9.

These changes significantly enhance the security posture and maintainability of the code while ensuring full backward compatibility.

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🔒 Security Enhancement: Externalize Credentials

The Problem

Hardcoded database credentials within test classes posed several risks:

• Exposure Risk: Potential for accidental exposure of default credentials and database structure.
• Insecure Patterns: Developers might copy these insecure test patterns into production code.
• Inflexibility: Inability to run tests against different database configurations without modifying the source code.

The Solution

All hardcoded credentials have been replaced with a system property-based configuration, falling back to the original default values if no properties are set.

Before:

return DriverManager.getConnection(url, "querydsl", "querydsl");

After:

var username = System.getProperty("mysql.username", "querydsl");
var password = System.getProperty("mysql.password", "querydsl");
return DriverManager.getConnection(url, username, password);

Benefits

• Backward Compatibility: Maintains default values, ensuring existing tests run without changes.
• Enhanced Security: Enables secure injection of credentials via environment variables or command-line arguments, following best practices.
• CI/CD Integration: Allows continuous integration pipelines to easily test against various database configurations.

Configuration Examples

Credentials can now be supplied via JVM system properties:

• MySQL: -Dmysql.username=testuser -Dmysql.password=testpass
• PostgreSQL: -Dpostgresql.username=pguser -Dpostgresql.password=pgpass
• SQL Server: -Dsqlserver.username=sa -Dsqlserver.password=SecurePassword123

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☕ Code Modernization: Update Reflection API

The Problem

The use of Class.newInstance() is outdated and has several drawbacks:

• Poor Exception Handling: It only throws InstantiationException and IllegalAccessException, hiding the underlying cause of failure.
• Security Concerns: It can bypass constructor access checks under certain security manager configurations.
• Inconsistent Behavior: Its behavior can vary across different JVM implementations.

The Solution

All calls have been updated to the modern reflection API, getDeclaredConstructor().newInstance(), which resolves these issues.

Before:

instance = (QueryHandler) Class.forName("com.querydsl.jpa.HibernateHandler").newInstance();

After:

instance = (QueryHandler) Class.forName("com.querydsl.jpa.HibernateHandler")
        .getDeclaredConstructor().newInstance();

Improvements

• Robust Error Handling: Provides more specific exceptions like NoSuchMethodException and InvocationTargetException.
• Improved Security: Explicitly accesses the constructor, making the intent clear and behavior more predictable.
• Future-Proofing: Ensures compatibility with Java 17 and newer versions.
• Clarity and Tooling: The modern API offers clearer intent and better support in modern IDEs.

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📂 Files Modified

Test Connection Classes

• querydsl-sql/src/test/java/com/querydsl/sql/Connections.java
  • Updated 7 database connection methods (DB2, Firebird, MySQL, Oracle, PostgreSQL, SQL Server, Teradata).
• querydsl-r2dbc/src/test/java/com/querydsl/r2dbc/Connections.java
  • Updated 3 R2DBC connection providers (MySQL, PostgreSQL, SQL Server).

Core Reflection Usage

• querydsl-core/src/main/java/com/querydsl/core/types/QBean.java
  • Enhanced create() method with proper exception handling and mapping.
• querydsl-jpa/src/main/java/com/querydsl/jpa/HQLTemplates.java
  • Updated Hibernate handler instantiation in the static initializer.
• querydsl-jpa/src/main/java/com/querydsl/jpa/EclipseLinkTemplates.java
  • Updated EclipseLink handler instantiation.
• querydsl-r2dbc/src/main/java/com/querydsl/r2dbc/JavaTypeMapping.java
  • Updated 7 JSR-310 type registrations for the modern Date/Time API.

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✅ Verification & Compatibility

Testing

• All modified files compile successfully.
• The core module builds without errors or new compiler warnings.
• Code formatting passes all project style checks.
• Public APIs are unchanged.

Backward Compatibility

This change is 100% backward compatible:

• Existing tests continue to function using the default credentials.
• No public method signatures have been altered.
• Behavior remains identical when system properties are not provided.

Migration Path

To use secure, externalized credentials:

1. Local Development (Maven):

   mvn test -Dmysql.username=dev_user -Dmysql.password=dev_pass

2. CI/CD Systems (e.g., GitHub Actions):

   env:
     MAVEN_OPTS: "-Dmysql.username=${{ secrets.DB_USER }} -Dmysql.password=${{ secrets.DB_PASS }}"

3. IDE Configuration:
   • Add the -D flags to the VM options of your test runner configuration.