auth

Authentication Module

The Authentication module provides comprehensive authentication capabilities for the Modular framework, including JWT tokens, session management, password hashing, and OAuth2/OIDC integration.

Features

• JWT Token Management: Generate, validate, and refresh JWT tokens with custom claims
• Password Security: Secure password hashing using bcrypt with configurable strength requirements
• Session Management: Create, manage, and track user sessions with configurable storage backends
• OAuth2/OIDC Support: Integration with OAuth2 providers like Google, GitHub, etc.
• Flexible Storage: Pluggable user and session storage interfaces with in-memory implementations included
• Security: Built-in protection against common authentication vulnerabilities

Installation

go get github.com/GoCodeAlone/modular/modules/auth

Configuration

Basic Configuration

auth:
  jwt:
    secret: "your-jwt-secret-key"
    expiration: "24h"
    refresh_expiration: "168h"
    issuer: "your-app-name"
  
  password:
    min_length: 8
    require_upper: true
    require_lower: true
    require_digit: true
    require_special: false
    bcrypt_cost: 12
  
  session:
    store: "memory"
    cookie_name: "session_id"
    max_age: "24h"
    secure: true
    http_only: true

OAuth2 Configuration

auth:
  oauth2:
    providers:
      google:
        client_id: "your-google-client-id"
        client_secret: "your-google-client-secret"
        redirect_url: "http://localhost:8080/auth/google/callback"
        scopes: ["openid", "email", "profile"]
        auth_url: "https://accounts.google.com/o/oauth2/auth"
        token_url: "https://oauth2.googleapis.com/token"
        user_info_url: "https://www.googleapis.com/oauth2/v2/userinfo"

Usage

Basic Setup

package main

import (
    "github.com/GoCodeAlone/modular"
    "github.com/GoCodeAlone/modular/modules/auth"
)

func main() {
    app := modular.NewApplication()
    
    // Register the auth module
    app.RegisterModule(auth.NewModule())
    
    // Start the application
    app.Start()
}

Using the Auth Service

// Get the auth service from the application
var authService auth.AuthService
err := app.GetService(auth.ServiceName, &authService)
if err != nil {
    log.Fatal(err)
}

// Hash a password
hashedPassword, err := authService.HashPassword("userpassword123")
if err != nil {
    log.Fatal(err)
}

// Verify a password
err = authService.VerifyPassword(hashedPassword, "userpassword123")
if err != nil {
    log.Println("Invalid password")
}

// Generate JWT tokens
customClaims := map[string]interface{}{
    "email": "user@example.com",
    "roles": []string{"user", "admin"},
    "permissions": []string{"read", "write"},
}

tokenPair, err := authService.GenerateToken("user-123", customClaims)
if err != nil {
    log.Fatal(err)
}

// Validate a token
claims, err := authService.ValidateToken(tokenPair.AccessToken)
if err != nil {
    log.Println("Invalid token:", err)
    return
}

log.Printf("User ID: %s, Email: %s", claims.UserID, claims.Email)

Session Management

// Create a session
metadata := map[string]interface{}{
    "ip_address": "127.0.0.1",
    "user_agent": "Mozilla/5.0...",
}

session, err := authService.CreateSession("user-123", metadata)
if err != nil {
    log.Fatal(err)
}

// Get a session
retrievedSession, err := authService.GetSession(session.ID)
if err != nil {
    log.Println("Session not found:", err)
    return
}

// Refresh a session (extend expiration)
refreshedSession, err := authService.RefreshSession(session.ID)
if err != nil {
    log.Fatal(err)
}

// Delete a session
err = authService.DeleteSession(session.ID)
if err != nil {
    log.Fatal(err)
}

OAuth2 Integration

// Get OAuth2 authorization URL
state := "random-state-string"
authURL, err := authService.GetOAuth2AuthURL("google", state)
if err != nil {
    log.Fatal(err)
}

// Redirect user to authURL...

// Exchange authorization code for user info
code := "authorization-code-from-callback"
result, err := authService.ExchangeOAuth2Code("google", code, state)
if err != nil {
    log.Fatal(err)
}

log.Printf("OAuth2 Result: %+v", result)

Custom User and Session Stores

You can implement custom storage backends by implementing the UserStore and SessionStore interfaces:

type DatabaseUserStore struct {
    db *sql.DB
}

func (s *DatabaseUserStore) GetUser(ctx context.Context, userID string) (*auth.User, error) {
    // Implement database query
}

func (s *DatabaseUserStore) CreateUser(ctx context.Context, user *auth.User) error {
    // Implement database insert
}

// Implement other UserStore methods...

// Register custom stores
app.RegisterService("user_store", &DatabaseUserStore{db: db})
app.RegisterService("session_store", &RedisSessionStore{client: redisClient})

API Reference

AuthService Interface

The main authentication service interface provides the following methods:

JWT Operations

• GenerateToken(userID string, claims map[string]interface{}) (*TokenPair, error)
• ValidateToken(token string) (*Claims, error)
• RefreshToken(refreshToken string) (*TokenPair, error)

Password Operations

• HashPassword(password string) (string, error)
• VerifyPassword(hashedPassword, password string) error
• ValidatePasswordStrength(password string) error

Session Operations

• CreateSession(userID string, metadata map[string]interface{}) (*Session, error)
• GetSession(sessionID string) (*Session, error)
• DeleteSession(sessionID string) error
• RefreshSession(sessionID string) (*Session, error)

OAuth2 Operations

• GetOAuth2AuthURL(provider, state string) (string, error)
• ExchangeOAuth2Code(provider, code, state string) (*OAuth2Result, error)

Data Structures

User

type User struct {
    ID           string                 `json:"id"`
    Email        string                 `json:"email"`
    PasswordHash string                 `json:"-"`
    Roles        []string               `json:"roles"`
    Permissions  []string               `json:"permissions"`
    Active       bool                   `json:"active"`
    CreatedAt    time.Time              `json:"created_at"`
    UpdatedAt    time.Time              `json:"updated_at"`
    LastLoginAt  *time.Time             `json:"last_login_at,omitempty"`
    Metadata     map[string]interface{} `json:"metadata,omitempty"`
}

Session

type Session struct {
    ID        string                 `json:"id"`
    UserID    string                 `json:"user_id"`
    CreatedAt time.Time              `json:"created_at"`
    ExpiresAt time.Time              `json:"expires_at"`
    IPAddress string                 `json:"ip_address"`
    UserAgent string                 `json:"user_agent"`
    Active    bool                   `json:"active"`
    Metadata  map[string]interface{} `json:"metadata,omitempty"`
}

TokenPair

type TokenPair struct {
    AccessToken  string    `json:"access_token"`
    RefreshToken string    `json:"refresh_token"`
    TokenType    string    `json:"token_type"`
    ExpiresIn    int64     `json:"expires_in"`
    ExpiresAt    time.Time `json:"expires_at"`
}

Testing

The module includes comprehensive tests covering all functionality:

cd modules/auth
go test -v

Test Coverage

• Configuration validation
• JWT token generation and validation
• Password hashing and verification
• Session management
• OAuth2 integration
• Memory store implementations
• Module lifecycle and dependency injection

Security Considerations

1. JWT Secret: Use a strong, randomly generated secret for JWT signing
2. Password Hashing: bcrypt cost should be at least 12 for production
3. Session Security: Enable secure and httpOnly flags for session cookies
4. OAuth2: Validate state parameters to prevent CSRF attacks
5. Token Expiration: Set appropriate expiration times for access and refresh tokens

Examples

See the examples/ directory for complete usage examples including:

• Basic authentication setup
• OAuth2 integration
• Custom middleware implementation
• Database integration patterns

Dependencies

• github.com/golang-jwt/jwt/v5 - JWT token handling
• golang.org/x/crypto - Password hashing
• golang.org/x/oauth2 - OAuth2 client implementation

License

This module is part of the Modular framework and is licensed under the same terms.