feat: add API token authentication (closes #87)

- Add api_tokens table migration (007)
- Add APIToken model with CRUD operations
- Generate tokens with upaas_ prefix + 32 hex chars
- Store SHA-256 hash of tokens (not plaintext)
- Update APISessionAuth middleware to check Bearer tokens
- Add POST/GET/DELETE /api/v1/tokens endpoints
- Token creation returns plaintext once; list never exposes it
- Expired and revoked tokens are rejected
- Tests for creation, listing, deletion, bearer auth, revocation

internal/middleware/middleware.go

@@ -19,8 +19,10 @@ import (
 	"golang.org/x/time/rate"
 
 	"git.eeqj.de/sneak/upaas/internal/config"
+	"git.eeqj.de/sneak/upaas/internal/database"
 	"git.eeqj.de/sneak/upaas/internal/globals"
 	"git.eeqj.de/sneak/upaas/internal/logger"
+	"git.eeqj.de/sneak/upaas/internal/models"
 	"git.eeqj.de/sneak/upaas/internal/service/auth"
 )
 
@@ -31,10 +33,11 @@ const corsMaxAge = 300
 type Params struct {
 	fx.In
 
-	Logger  *logger.Logger
-	Globals *globals.Globals
-	Config  *config.Config
-	Auth    *auth.Service
+	Logger   *logger.Logger
+	Globals  *globals.Globals
+	Config   *config.Config
+	Auth     *auth.Service
+	Database *database.Database
 }
 
 // Middleware provides HTTP middleware.
@@ -235,9 +238,9 @@ func (m *Middleware) CSRF() func(http.Handler) http.Handler {
 // loginRateLimit configures the login rate limiter.
 const (
 	loginRateLimit      = rate.Limit(5.0 / 60.0) // 5 requests per 60 seconds
-	loginBurst          = 5                       // allow burst of 5
-	limiterExpiry       = 10 * time.Minute        // evict entries not seen in 10 minutes
-	limiterCleanupEvery = 1 * time.Minute         // sweep interval
+	loginBurst          = 5                      // allow burst of 5
+	limiterExpiry       = 10 * time.Minute       // evict entries not seen in 10 minutes
+	limiterCleanupEvery = 1 * time.Minute        // sweep interval
 )
 
 // ipLimiterEntry stores a rate limiter with its last-seen timestamp.
@@ -249,8 +252,8 @@ type ipLimiterEntry struct {
 // ipLimiter tracks per-IP rate limiters for login attempts with automatic
 // eviction of stale entries to prevent unbounded memory growth.
 type ipLimiter struct {
-	mu       sync.Mutex
-	limiters map[string]*ipLimiterEntry
+	mu        sync.Mutex
+	limiters  map[string]*ipLimiterEntry
 	lastSweep time.Time
 }
 
@@ -339,18 +342,36 @@ func (m *Middleware) LoginRateLimit() func(http.Handler) http.Handler {
 	}
 }
 
-// APISessionAuth returns middleware that requires session authentication for API routes.
-// Unlike SessionAuth, it returns JSON 401 responses instead of redirecting to /login.
+// bearerPrefix is the expected prefix for Authorization headers.
+const bearerPrefix = "Bearer "
+
+// APISessionAuth returns middleware that requires authentication
+// for API routes. It checks Bearer token first, then falls back
+// to session cookie. Returns JSON 401 on failure.
 func (m *Middleware) APISessionAuth() func(http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(
 			writer http.ResponseWriter,
 			request *http.Request,
 		) {
-			user, err := m.params.Auth.GetCurrentUser(request.Context(), request)
+			// Try Bearer token first.
+			if m.tryBearerAuth(request) {
+				next.ServeHTTP(writer, request)
+
+				return
+			}
+
+			// Fall back to session cookie.
+			user, err := m.params.Auth.GetCurrentUser(
+				request.Context(), request,
+			)
 			if err != nil || user == nil {
 				writer.Header().Set("Content-Type", "application/json")
-				http.Error(writer, `{"error":"unauthorized"}`, http.StatusUnauthorized)
+				http.Error(
+					writer,
+					`{"error":"unauthorized"}`,
+					http.StatusUnauthorized,
+				)
 
 				return
 			}
@@ -403,3 +424,35 @@ func (m *Middleware) SetupRequired() func(http.Handler) http.Handler {
 		})
 	}
 }
+
+// tryBearerAuth checks for a valid Bearer token in the
+// Authorization header.
+func (m *Middleware) tryBearerAuth(request *http.Request) bool {
+	authHeader := request.Header.Get("Authorization")
+	if !strings.HasPrefix(authHeader, bearerPrefix) {
+		return false
+	}
+
+	rawToken := strings.TrimPrefix(authHeader, bearerPrefix)
+	if rawToken == "" {
+		return false
+	}
+
+	tokenHash := database.HashAPIToken(rawToken)
+
+	apiToken, err := models.FindAPITokenByHash(
+		request.Context(), m.params.Database, tokenHash,
+	)
+	if err != nil || apiToken == nil {
+		return false
+	}
+
+	if apiToken.IsExpired() {
+		return false
+	}
+
+	// Update last_used_at (best effort).
+	_ = apiToken.TouchLastUsed(request.Context())
+
+	return true
+}