OCPP 1.6 Messages for Go

A type-safe, OCPP 1.6-compliant Go library providing message structures and validation for Electric Vehicle charging station communication.

Overview

This library implements OCPP (Open Charge Point Protocol) 1.6 message types with strict validation, following Go best practices and the official OCPP 1.6 specification. It is designed as a foundation for building OCPP-compliant charging station management systems and charge point implementations.

Status: 🚧 Active Development (Pre-1.0)

Key Features

• ✅ Type Safety - Constructor pattern with validation (New*() functions)
• ✅ OCPP 1.6 Compliance - Strict adherence to protocol specification
• ✅ Immutable Types - Thread-safe by design with value receivers
• ✅ Comprehensive Testing - Unit, integration, race, and fuzz tests
• ✅ Zero Panics - All errors returned, never panicked
• ✅ Well Documented - Full godoc coverage and examples

Installation

go get github.com/aasanchez/ocpp16messages

Requirements: Go 1.24 or later

Project Structure

.
├── shared/types/          # Core OCPP data types
│   ├── cistring.go       # CiString20/25/50/255/500 types
│   ├── datetime.go       # RFC3339 DateTime with UTC normalization
│   ├── integer.go        # Validated uint16 Integer type
│   ├── errors.go         # Reusable error constructors
│   └── tests/            # Unit and integration tests
├── messages/
│   └── authorize/        # Authorize message implementation
│       ├── request.go    # Authorize request message
│       └── types/        # Authorize-specific types
│           ├── idtoken.go      # IdToken type
│           ├── request.go      # Request payload
│           └── tests/          # Message-specific tests
└── SECURITY.md           # Security policy and vulnerability reporting

Usage

Core Types

The library provides validated OCPP 1.6 data types:

import "github.com/aasanchez/ocpp16messages/shared/types"

// CiString types (case-insensitive, ASCII printable, length-validated)
idTag, err := types.NewCiString20Type("RFID-ABC123")
if err != nil {
    // Handle validation error (length > 20 or non-ASCII chars)
}

// DateTime (RFC3339, auto-normalized to UTC)
timestamp, err := types.NewDateTime("2025-01-02T15:04:05Z")
if err != nil {
    // Handle parsing error
}

// Integer (validated uint16)
retryCount, err := types.NewInteger("3")
if err != nil {
    // Handle conversion/range error
}

Message Types

import (
    "github.com/aasanchez/ocpp16messages/messages/authorize"
    mat "github.com/aasanchez/ocpp16messages/messages/authorize/types"
)

// Create request payload
payload := mat.Request{
    IdTag: "RFID-ABC123",
}

// Validate payload
if err := payload.Validate(); err != nil {
    // Handle validation error
}

// Create message
request, err := authorize.NewRequest(payload)
if err != nil {
    // Handle construction error
}

Development

Prerequisites

• Go 1.24+
• golangci-lint
• staticcheck
• gci, gofumpt, golines (formatters)

Common Commands

# Install dependencies
go mod tidy

# Run tests
make test                   # Unit and example tests
make test-coverage          # Generate HTML coverage report
make test-race              # Race detector (concurrency safety)
make test-fuzz              # Fuzz tests (10s per function, configurable with FUZZTIME)
make test-all               # All test types

# Code quality
make lint                   # Run all linters (golangci-lint, go vet, staticcheck)
make format                 # Format code (gci, gofumpt, golines, gofmt)

# Documentation
make pkgsite                # Start local documentation server at http://localhost:8080

Test Coverage

Reports are generated in the reports/ directory:

• reports/coverage.out - Coverage data
• reports/golangci-lint.txt - Lint results

OCPP 1.6 Compliance

Type System

OCPP Type	Go Type	Validation
CiString20Type	types.CiString20Type	Length ≤ 20, ASCII printable (32–126)
CiString25Type	types.CiString25Type	Length ≤ 25, ASCII printable (32–126)
CiString50Type	types.CiString50Type	Length ≤ 50, ASCII printable (32–126)
CiString255Type	types.CiString255Type	Length ≤ 255, ASCII printable (32–126)
CiString500Type	types.CiString500Type	Length ≤ 500, ASCII printable (32–126)
dateTime	types.DateTime	RFC3339, normalized to UTC
integer	types.Integer	uint16 (0–65535)

Message Implementation Status

• ✅ Authorize - Request/Response
• 🚧 Additional messages in development

Design Principles

1. Constructor Validation - All types require New*() constructors that validate input
2. Immutability - Types use private fields and value receivers
3. Error Wrapping - Context preserved via fmt.Errorf with %w
4. No Panics - Library never panics; all errors returned
5. Thread Safety - All types proven safe via race tests
6. Go Conventions - Follows Effective Go guidelines

Security

Security is critical for EV charging infrastructure. This library:

• Validates all input at construction time
• Prevents injection attacks via strict type constraints
• Provides clear error messages without exposing internals
• Uses immutable types to prevent tampering
• Is designed for safe concurrent use

Reporting vulnerabilities: See SECURITY.md for our security policy and responsible disclosure process.

Contributing

We welcome contributions! Please:

1. Follow Go best practices and Effective Go
2. Add tests for all new functionality
3. Ensure make test-all passes
4. Run make lint and make format before committing
5. Document all exported types and functions
6. Follow the existing code style

See CLAUDE.md for detailed development guidelines.

License

See LICENSE

Resources

• OCPP 1.6 Specification
• Go Package Documentation
• Security Policy
• Development Guide