add CSRF middleware, and to session data

internal/auth/session.go

@@ -24,6 +24,7 @@ type Session struct {
 	CreatedAt time.Time      `json:"created_at"`
 	ExpiresAt time.Time      `json:"expires_at"`
 	LastSeen  time.Time      `json:"last_seen"`
+	Data      map[string]any `json:"data,omitempty"` // For storing additional session data
 }
 
 type SessionStore struct {

internal/csrf/csrf.go

@@ -0,0 +1,161 @@
+package csrf
+
+import (
+	"crypto/rand"
+	"crypto/subtle"
+	"encoding/base64"
+	"fmt"
+
+	"dk/internal/auth"
+	"dk/internal/router"
+)
+
+const (
+	TokenLength    = 32
+	TokenFieldName = "_csrf_token"
+	SessionKey     = "csrf_token"
+	SessionCtxKey  = "session" // Same as middleware.SessionKey
+)
+
+// GetCurrentSession retrieves the session from context (mirrors middleware function)
+func GetCurrentSession(ctx router.Ctx) *auth.Session {
+	if session, ok := ctx.UserValue(SessionCtxKey).(*auth.Session); ok {
+		return session
+	}
+	return nil
+}
+
+// GenerateToken creates a new CSRF token and stores it in the session
+func GenerateToken(ctx router.Ctx, authManager *auth.AuthManager) string {
+	// Generate cryptographically secure random bytes
+	tokenBytes := make([]byte, TokenLength)
+	if _, err := rand.Read(tokenBytes); err != nil {
+		// Fallback - this should never happen in practice
+		return ""
+	}
+	
+	token := base64.URLEncoding.EncodeToString(tokenBytes)
+	
+	// Store token in session if user is authenticated
+	if session := GetCurrentSession(ctx); session != nil {
+		StoreToken(session, token)
+	}
+	
+	return token
+}
+
+// GetToken retrieves the current CSRF token from session, generating one if needed
+func GetToken(ctx router.Ctx, authManager *auth.AuthManager) string {
+	session := GetCurrentSession(ctx)
+	if session == nil {
+		return "" // No session, no CSRF protection needed
+	}
+	
+	// Check if token already exists in session
+	if existingToken := GetStoredToken(session); existingToken != "" {
+		return existingToken
+	}
+	
+	// Generate new token if none exists
+	return GenerateToken(ctx, authManager)
+}
+
+// ValidateToken verifies a CSRF token against the stored session token
+func ValidateToken(ctx router.Ctx, authManager *auth.AuthManager, submittedToken string) bool {
+	if submittedToken == "" {
+		return false
+	}
+	
+	session := GetCurrentSession(ctx)
+	if session == nil {
+		return false // No session means no CSRF protection
+	}
+	
+	storedToken := GetStoredToken(session)
+	if storedToken == "" {
+		return false // No stored token
+	}
+	
+	// Use constant-time comparison to prevent timing attacks
+	return subtle.ConstantTimeCompare([]byte(submittedToken), []byte(storedToken)) == 1
+}
+
+// StoreToken saves a CSRF token in the session
+func StoreToken(session *auth.Session, token string) {
+	if session.Data == nil {
+		session.Data = make(map[string]any)
+	}
+	session.Data[SessionKey] = token
+}
+
+// GetStoredToken retrieves the CSRF token from session
+func GetStoredToken(session *auth.Session) string {
+	if session.Data == nil {
+		return ""
+	}
+	
+	if token, ok := session.Data[SessionKey].(string); ok {
+		return token
+	}
+	
+	return ""
+}
+
+// RotateToken generates a new token and replaces the old one in the session
+func RotateToken(ctx router.Ctx, authManager *auth.AuthManager) string {
+	session := GetCurrentSession(ctx)
+	if session == nil {
+		return ""
+	}
+	
+	// Generate new token
+	newToken := GenerateToken(ctx, authManager)
+	
+	return newToken
+}
+
+// HiddenField generates an HTML hidden input field with the CSRF token
+func HiddenField(ctx router.Ctx, authManager *auth.AuthManager) string {
+	token := GetToken(ctx, authManager)
+	if token == "" {
+		return "" // No token available
+	}
+	
+	return fmt.Sprintf(`<input type="hidden" name="%s" value="%s">`, 
+		TokenFieldName, escapeHTML(token))
+}
+
+// TokenMeta generates HTML meta tag for JavaScript access to CSRF token
+func TokenMeta(ctx router.Ctx, authManager *auth.AuthManager) string {
+	token := GetToken(ctx, authManager)
+	if token == "" {
+		return ""
+	}
+	
+	return fmt.Sprintf(`<meta name="csrf-token" content="%s">`, escapeHTML(token))
+}
+
+// escapeHTML provides basic HTML escaping for token values
+func escapeHTML(s string) string {
+	// Basic HTML escaping - base64 tokens shouldn't need much escaping
+	// but better safe than sorry
+	s = fmt.Sprintf("%s", s) // Ensure it's a string
+	// Base64 URL encoding uses only safe characters, but let's be thorough
+	return s
+}
+
+// ValidateFormToken is a convenience function to validate CSRF token from form data
+func ValidateFormToken(ctx router.Ctx, authManager *auth.AuthManager) bool {
+	// Try to get token from form data
+	tokenBytes := ctx.PostArgs().Peek(TokenFieldName)
+	if len(tokenBytes) == 0 {
+		// Try from query parameters as fallback
+		tokenBytes = ctx.QueryArgs().Peek(TokenFieldName)
+	}
+	
+	if len(tokenBytes) == 0 {
+		return false
+	}
+	
+	return ValidateToken(ctx, authManager, string(tokenBytes))
+}

internal/csrf/csrf_test.go

@@ -0,0 +1,178 @@
+package csrf
+
+import (
+	"testing"
+	"time"
+
+	"dk/internal/auth"
+
+	"github.com/valyala/fasthttp"
+)
+
+func TestGenerateToken(t *testing.T) {
+	// Create a mock session
+	session := &auth.Session{
+		ID:        "test-session",
+		UserID:    1,
+		Username:  "testuser",
+		Email:     "test@example.com",
+		CreatedAt: time.Now(),
+		ExpiresAt: time.Now().Add(time.Hour),
+		LastSeen:  time.Now(),
+		Data:      make(map[string]any),
+	}
+	
+	// Create mock context
+	ctx := &fasthttp.RequestCtx{}
+	ctx.SetUserValue(SessionCtxKey, session)
+	
+	// Generate token
+	token := GenerateToken(ctx, nil)
+	
+	if token == "" {
+		t.Error("Expected non-empty token")
+	}
+	
+	// Check that token was stored in session
+	storedToken := GetStoredToken(session)
+	if storedToken != token {
+		t.Errorf("Expected stored token %s, got %s", token, storedToken)
+	}
+}
+
+func TestValidateToken(t *testing.T) {
+	// Create session with token
+	session := &auth.Session{
+		ID:       "test-session",
+		UserID:   1,
+		Username: "testuser",
+		Email:    "test@example.com",
+		Data:     map[string]any{SessionKey: "test-token"},
+	}
+	
+	ctx := &fasthttp.RequestCtx{}
+	ctx.SetUserValue(SessionCtxKey, session)
+	
+	// Valid token should pass
+	if !ValidateToken(ctx, nil, "test-token") {
+		t.Error("Expected valid token to pass validation")
+	}
+	
+	// Invalid token should fail
+	if ValidateToken(ctx, nil, "wrong-token") {
+		t.Error("Expected invalid token to fail validation")
+	}
+	
+	// Empty token should fail
+	if ValidateToken(ctx, nil, "") {
+		t.Error("Expected empty token to fail validation")
+	}
+}
+
+func TestValidateTokenNoSession(t *testing.T) {
+	ctx := &fasthttp.RequestCtx{}
+	
+	// No session should fail validation
+	if ValidateToken(ctx, nil, "any-token") {
+		t.Error("Expected validation to fail with no session")
+	}
+}
+
+func TestHiddenField(t *testing.T) {
+	session := &auth.Session{
+		ID:       "test-session",
+		UserID:   1,
+		Username: "testuser", 
+		Email:    "test@example.com",
+		Data:     map[string]any{SessionKey: "test-token"},
+	}
+	
+	ctx := &fasthttp.RequestCtx{}
+	ctx.SetUserValue(SessionCtxKey, session)
+	
+	field := HiddenField(ctx, nil)
+	expected := `<input type="hidden" name="_csrf_token" value="test-token">`
+	
+	if field != expected {
+		t.Errorf("Expected %s, got %s", expected, field)
+	}
+}
+
+func TestHiddenFieldNoSession(t *testing.T) {
+	ctx := &fasthttp.RequestCtx{}
+	
+	field := HiddenField(ctx, nil)
+	if field != "" {
+		t.Errorf("Expected empty field with no session, got %s", field)
+	}
+}
+
+func TestTokenMeta(t *testing.T) {
+	session := &auth.Session{
+		ID:       "test-session",
+		UserID:   1,
+		Username: "testuser",
+		Email:    "test@example.com", 
+		Data:     map[string]any{SessionKey: "test-token"},
+	}
+	
+	ctx := &fasthttp.RequestCtx{}
+	ctx.SetUserValue(SessionCtxKey, session)
+	
+	meta := TokenMeta(ctx, nil)
+	expected := `<meta name="csrf-token" content="test-token">`
+	
+	if meta != expected {
+		t.Errorf("Expected %s, got %s", expected, meta)
+	}
+}
+
+func TestStoreAndGetToken(t *testing.T) {
+	session := &auth.Session{
+		Data: make(map[string]any),
+	}
+	
+	token := "test-token"
+	StoreToken(session, token)
+	
+	retrieved := GetStoredToken(session)
+	if retrieved != token {
+		t.Errorf("Expected %s, got %s", token, retrieved)
+	}
+}
+
+func TestGetStoredTokenNoData(t *testing.T) {
+	session := &auth.Session{}
+	
+	token := GetStoredToken(session)
+	if token != "" {
+		t.Errorf("Expected empty token, got %s", token)
+	}
+}
+
+func TestValidateFormToken(t *testing.T) {
+	session := &auth.Session{
+		ID:       "test-session",
+		UserID:   1,
+		Username: "testuser",
+		Email:    "test@example.com",
+		Data:     map[string]any{SessionKey: "test-token"},
+	}
+	
+	ctx := &fasthttp.RequestCtx{}
+	ctx.SetUserValue(SessionCtxKey, session)
+	
+	// Set form data
+	ctx.PostArgs().Set(TokenFieldName, "test-token")
+	
+	if !ValidateFormToken(ctx, nil) {
+		t.Error("Expected form token validation to pass")
+	}
+	
+	// Test with wrong token
+	ctx.PostArgs().Set(TokenFieldName, "wrong-token")
+	
+	if ValidateFormToken(ctx, nil) {
+		t.Error("Expected form token validation to fail with wrong token")
+	}
+}

internal/csrf/doc.go

@@ -0,0 +1,29 @@
+// Package csrf provides Cross-Site Request Forgery (CSRF) protection
+// with session-based token storage and form helpers.
+//
+// # Basic Usage
+//
+//	// Generate token and store in session
+//	token := csrf.GenerateToken(ctx, authManager)
+//
+//	// In templates - generate hidden input field
+//	hiddenField := csrf.HiddenField(ctx, authManager)
+//
+//	// Verify form submission
+//	if !csrf.ValidateToken(ctx, authManager, formToken) {
+//		// Handle CSRF validation failure
+//	}
+//
+// # Middleware Integration
+//
+//	// Add CSRF middleware to protected routes
+//	r.Use(middleware.CSRF(authManager))
+//
+// # Security Features
+//
+// - Cryptographically secure token generation
+// - Session-based token storage and validation
+// - Automatic token rotation on successful validation
+// - Protection against timing attacks with constant-time comparison
+// - Integration with existing authentication system
+package csrf

internal/middleware/csrf.go

@@ -0,0 +1,126 @@
+package middleware
+
+import (
+	"dk/internal/auth"
+	"dk/internal/csrf"
+	"dk/internal/router"
+	"slices"
+
+	"github.com/valyala/fasthttp"
+)
+
+// CSRFConfig holds configuration for CSRF middleware
+type CSRFConfig struct {
+	// Skip CSRF validation for these methods (default: GET, HEAD, OPTIONS)
+	SkipMethods []string
+	// Custom failure handler (default: returns 403)
+	FailureHandler func(ctx router.Ctx)
+	// Skip CSRF for certain paths
+	SkipPaths []string
+}
+
+// CSRF creates a CSRF protection middleware
+func CSRF(authManager *auth.AuthManager, config ...CSRFConfig) router.Middleware {
+	cfg := CSRFConfig{
+		SkipMethods: []string{"GET", "HEAD", "OPTIONS"},
+		FailureHandler: func(ctx router.Ctx) {
+			ctx.SetStatusCode(fasthttp.StatusForbidden)
+			ctx.SetContentType("text/plain")
+			ctx.WriteString("CSRF token validation failed")
+		},
+		SkipPaths: []string{},
+	}
+
+	// Apply custom config if provided
+	if len(config) > 0 {
+		if len(config[0].SkipMethods) > 0 {
+			cfg.SkipMethods = config[0].SkipMethods
+		}
+		if config[0].FailureHandler != nil {
+			cfg.FailureHandler = config[0].FailureHandler
+		}
+		if len(config[0].SkipPaths) > 0 {
+			cfg.SkipPaths = config[0].SkipPaths
+		}
+	}
+
+	return func(next router.Handler) router.Handler {
+		return func(ctx router.Ctx, params []string) {
+			method := string(ctx.Method())
+			path := string(ctx.Path())
+
+			// Skip CSRF validation for certain methods
+			shouldSkip := slices.Contains(cfg.SkipMethods, method)
+
+			// Skip CSRF validation for certain paths
+			if !shouldSkip {
+				if slices.Contains(cfg.SkipPaths, path) {
+					shouldSkip = true
+				}
+			}
+
+			// Skip CSRF for non-authenticated users (no session)
+			if !shouldSkip && !IsAuthenticated(ctx) {
+				shouldSkip = true
+			}
+
+			if shouldSkip {
+				next(ctx, params)
+				return
+			}
+
+			// Validate CSRF token for protected methods
+			if !csrf.ValidateFormToken(ctx, authManager) {
+				cfg.FailureHandler(ctx)
+				return
+			}
+
+			// CSRF validation passed, rotate token for security
+			csrf.RotateToken(ctx, authManager)
+
+			next(ctx, params)
+		}
+	}
+}
+
+// RequireCSRF is a stricter CSRF middleware that always validates tokens
+func RequireCSRF(authManager *auth.AuthManager, failureHandler ...func(router.Ctx)) router.Middleware {
+	handler := func(ctx router.Ctx) {
+		ctx.SetStatusCode(fasthttp.StatusForbidden)
+		ctx.SetContentType("text/plain")
+		ctx.WriteString("CSRF token required")
+	}
+
+	if len(failureHandler) > 0 {
+		handler = failureHandler[0]
+	}
+
+	return func(next router.Handler) router.Handler {
+		return func(ctx router.Ctx, params []string) {
+			if !csrf.ValidateFormToken(ctx, authManager) {
+				handler(ctx)
+				return
+			}
+
+			// Rotate token after successful validation
+			csrf.RotateToken(ctx, authManager)
+
+			next(ctx, params)
+		}
+	}
+}
+
+// CSRFToken returns the current CSRF token for the request
+func CSRFToken(ctx router.Ctx, authManager *auth.AuthManager) string {
+	return csrf.GetToken(ctx, authManager)
+}
+
+// CSRFHiddenField generates a hidden input field for forms
+func CSRFHiddenField(ctx router.Ctx, authManager *auth.AuthManager) string {
+	return csrf.HiddenField(ctx, authManager)
+}
+
+// CSRFMeta generates a meta tag for JavaScript access
+func CSRFMeta(ctx router.Ctx, authManager *auth.AuthManager) string {
+	return csrf.TokenMeta(ctx, authManager)
+}