Module validation

Metadata validation utilities

Metadata Validation System for .NET Assemblies

This module provides a comprehensive validation framework for ensuring metadata integrity, type safety, and ECMA-335 compliance across .NET assembly structures. The validation system operates at multiple levels, from basic structural validation to complex semantic analysis, ensuring that loaded metadata conforms to runtime requirements and specification constraints.

Architecture Overview

The validation system is designed as a modular, configurable framework:

┌─────────────────┐    ┌──────────────────┐    ┌─────────────────┐
│ ValidationConfig│───▶│   Orchestrator   │───▶│ Specific        │
│                 │    │                  │    │ Validators      │
└─────────────────┘    └──────────────────┘    └─────────────────┘
                                │                        │
                                ▼                        ▼
                       ┌─────────────────┐    ┌─────────────────┐
                       │ Error Collection│    │ Parallel        │
                       │ & Reporting     │    │ Processing      │
                       └─────────────────┘    └─────────────────┘

Validation Categories

Structural Validation

• Token Validation: Format, consistency, and reference integrity
• Table Structure: Row counts, column validation, heap references
• Signature Parsing: Type signatures, method signatures, field types
• PE Structure: Headers, section alignment, file format compliance

Semantic Validation

• Type System Consistency: Inheritance rules, interface implementation
• Method Constraints: Abstract/concrete rules, constructor validation
• Field Layout: Memory layout, overlap detection, alignment validation
• Access Control: Visibility rules, accessibility constraints

Cross-Table Validation

• Reference Consistency: Cross-table token references
• Relationship Integrity: Parent-child relationships, ownership
• Index Validation: Coded indexes, table relationships
• Constraint Satisfaction: Generic constraints, type compatibility

Validation Components

Component	Purpose	Validation Scope
ValidationConfig	Configuration and control	Validation behavior and performance
Orchestrator	Coordination and execution	Overall validation workflow
TokenValidator	Token integrity	Token format and reference validation
FieldValidator	Field layout	Memory layout and overlap detection
MethodValidator	Method constraints	Constructor and abstract method rules
LayoutValidator	Class layout	Packing and size validation
SemanticValidator	Type semantics	Inheritance and interface validation
ConstraintValidator	Generic constraints	Generic parameter validation
NestedClassValidator	Nested classes	Nesting rules and circular detection

Validation Levels

The validation system supports multiple validation levels to balance thoroughness with performance:

Disabled (ValidationConfig::disabled())

• Use case: Maximum performance, trusted input
• Validation: None (unsafe for untrusted assemblies)

Minimal (ValidationConfig::minimal())

• Use case: High performance with basic safety
• Validation: Essential structural validation only

Production (ValidationConfig::production())

• Use case: Production environments, balanced validation
• Validation: Runtime-equivalent validation rules

Comprehensive (ValidationConfig::comprehensive())

• Use case: Development, debugging, thorough analysis
• Validation: All available validation rules

Strict (ValidationConfig::strict())

• Use case: Security analysis, format compliance checking
• Validation: Strictest possible validation (may have false positives)

Error Reporting

Validation errors are collected and reported with comprehensive context:

• Error Location: Type, method, field, or table where error occurred
• Error Category: Structural, semantic, or compliance violation
• Error Details: Specific constraint violated and diagnostic information
• Corrective Guidance: Suggestions for fixing validation issues
• Token Context: Relevant metadata tokens for debugging

Runtime Compliance

The validation system implements validation rules that match .NET runtime behavior:

• CoreCLR Compatibility: Validation rules derived from .NET Core runtime
• ECMA-335 Compliance: Full specification compliance checking
• Error Parity: Similar error messages to runtime validation
• Performance Matching: Validation overhead similar to runtime loading

Completed Validation Features

• Cross-table validation: Token consistency, semantic validation, method validation
• Field layout validation: Overlap detection, boundary checking for explicit layouts
• Type system validation: Inheritance rules, sealed/abstract constraints
• Semantic validation: Interface rules, inheritance validation, type system consistency
• Method validation: Constructor rules, abstract method validation, parameter validation
• Nested class validation: Circular reference detection and depth limits
• Configuration system: Flexible validation configuration and performance tuning
• Parallel processing: Multi-core validation for large assemblies

Future Validation Enhancements

Infrastructure & Core Validation

• Coded Index Runtime Validation - Enhanced coded index validation
• UTF-8 String Validation - Comprehensive string heap validation
• Malformed Assembly Recovery - Better handling of corrupted assemblies

PE & File Structure Validation

• Comprehensive PE Header Validation - Thorough PE file validation
• Security Validation - Additional security constraint checking
• File Format Recovery - Improved corrupted file handling

IL & Method Validation

• IL Instruction Sequence Validation - CIL instruction flow validation
• Stack Depth Validation - Operand stack validation
• CIL Verification Rules - Full CIL verification implementation

Table-Specific Validation

• Parameter Type Compatibility - Enhanced parameter validation
• Signature Type Validation - Type compatibility in signatures
• Range Validation - Bounds checking for computed ranges
• Semantic Attribute Validation - Method signature compatibility

Total: ~18 remaining validation enhancements across different categories, ranging from critical infrastructure validation to table-specific edge case validation.

Thread Safety

All validation components are designed for thread safety:

• Stateless validators safe for concurrent use
• Parallel processing using Rayon for internal operations
• Thread-safe error collection and reporting
• No shared mutable state in validation logic

References

• ECMA-335: Common Language Infrastructure (CLI) Standard
• .NET Core Runtime: Validation implementation analysis
• ISO/IEC 23271: Common Language Infrastructure specification
• Microsoft .NET Documentation: Assembly loading and validation

Structs

ValidationConfig

Configuration for controlling validation behavior and performance. Configuration for metadata validation during assembly loading.