Heavy security and file splitting

internal/config/config.go

@@ -22,6 +22,7 @@ const (
 	defaultReadTimeout               = "30s"
 	defaultWriteTimeout              = "30s"
 	defaultIdleTimeout               = "120s"
+	defaultShutdownTimeout           = "10s"
 	defaultMaxHeaderBytes            = 1 << 20
 	defaultAccessLogEnabled          = true
 	defaultAccessLogMaxSize          = "100MiB"
@@ -42,6 +43,7 @@ const (
 	defaultAPIReadRateLimitBurst     = 100
 	defaultAPIWriteRequestsPerMinute = 30
 	defaultAPIWriteRateLimitBurst    = 10
+	defaultHSTSEnabled               = true
 	maxDefaultTTLLimit               = 24 * time.Hour
 	minCleanupInterval               = 10 * time.Second
 	envPrefix                        = "SCRATCHBOX_"
@@ -51,7 +53,7 @@ type Config struct {
 	Server   ServerConfig   `yaml:"server" comment:"HTTP listener settings."`
 	Limits   LimitsConfig   `yaml:"limits" comment:"Upload, expiration, and raw cache defaults."`
 	Storage  StorageConfig  `yaml:"storage" comment:"Filesystem storage location and cleanup cadence."`
-	Security SecurityConfig `yaml:"security" comment:"Write-route IP restrictions and rate limiting."`
+	Security SecurityConfig `yaml:"security" comment:"Write-route IP restrictions, rate limiting, and HSTS."`
 }
 
 type ServerConfig struct {
@@ -60,12 +62,14 @@ type ServerConfig struct {
 	ReadTimeout          string          `yaml:"read_timeout" comment:"Maximum duration for reading the full request, including body. Must be > 0."`
 	WriteTimeout         string          `yaml:"write_timeout" comment:"Maximum duration before timing out writes of a response. Must be > 0."`
 	IdleTimeout          string          `yaml:"idle_timeout" comment:"Maximum amount of time to wait for the next request when keep-alives are enabled. Must be > 0."`
+	ShutdownTimeout      string          `yaml:"shutdown_timeout" comment:"Graceful shutdown timeout for the HTTP server. Must be > 0."`
 	MaxHeaderBytes       int             `yaml:"max_header_bytes" comment:"Maximum size of request headers in bytes. Must be > 0."`
 	AccessLog            AccessLogConfig `yaml:"access_log" comment:"Access log settings for all HTTP requests."`
 	ReadHeaderTimeoutDur time.Duration   `yaml:"-"`
 	ReadTimeoutDur       time.Duration   `yaml:"-"`
 	WriteTimeoutDur      time.Duration   `yaml:"-"`
 	IdleTimeoutDur       time.Duration   `yaml:"-"`
+	ShutdownTimeoutDur   time.Duration   `yaml:"-"`
 }
 
 type AccessLogConfig struct {
@@ -96,10 +100,11 @@ type StorageConfig struct {
 type SecurityConfig struct {
 	AllowedIPs           []string        `yaml:"allowed_ips" comment:"Allowlist for POST /api/scratch as IPs or CIDRs (examples: 127.0.0.1, 192.168.1.0/24). Keep 127.0.0.1 for local access; add trusted ranges as needed. Empty means unrestricted."`
 	TrustProxyHeaders    bool            `yaml:"trust_proxy_headers" comment:"Honor X-Forwarded-For / X-Real-IP only when request source IP matches security.trusted_proxy_ips."`
-	TrustedProxyIPs      []string        `yaml:"trusted_proxy_ips" comment:"IPs/CIDRs of reverse proxies allowed to supply forwarded client IP headers. Required when trust_proxy_headers is true."`
+	TrustedProxyIPs      []string        `yaml:"trusted_proxy_ips" comment:"IPs/CIDRs of reverse proxies allowed to supply forwarded client IP headers. Required when trust_proxy_headers is true. Must be the *immediate* proxies only (never 0/0 or untrusted ranges)."`
 	RateLimitUI          RateLimitConfig `yaml:"rate_limit_ui" comment:"Per-client token bucket on UI routes (/, /u, /s/{id})."`
 	RateLimitAPIRead     RateLimitConfig `yaml:"rate_limit_api_read" comment:"Per-client token bucket on API read routes (GET /api/config, GET /api/scratch/{id}, GET /api/raw/{id})."`
 	RateLimitAPIWrite    RateLimitConfig `yaml:"rate_limit_api_write" comment:"Per-client token bucket on API write route (POST /api/scratch)."`
+	HSTSEnabled          bool            `yaml:"hsts_enabled" comment:"Enable Strict-Transport-Security (HSTS) header. Recommended when behind a TLS-terminating reverse proxy for public deployments (default: true). Set to false for local-only HTTP use without proxies."`
 	AllowedPrefixes      []netip.Prefix  `yaml:"-"`
 	TrustedProxyPrefixes []netip.Prefix  `yaml:"-"`
 }
@@ -150,6 +155,7 @@ func defaults() Config {
 			ReadTimeout:       defaultReadTimeout,
 			WriteTimeout:      defaultWriteTimeout,
 			IdleTimeout:       defaultIdleTimeout,
+			ShutdownTimeout:   defaultShutdownTimeout,
 			MaxHeaderBytes:    defaultMaxHeaderBytes,
 			AccessLog: AccessLogConfig{
 				Enabled:    defaultAccessLogEnabled,
@@ -186,6 +192,7 @@ func defaults() Config {
 				RequestsPerMinute: defaultAPIWriteRequestsPerMinute,
 				Burst:             defaultAPIWriteRateLimitBurst,
 			},
+			HSTSEnabled: defaultHSTSEnabled,
 		},
 	}
 }
@@ -230,6 +237,15 @@ func (c *Config) Validate() error {
 	}
 	c.Server.IdleTimeoutDur = idleTimeout
 
+	shutdownTimeout, err := time.ParseDuration(strings.TrimSpace(c.Server.ShutdownTimeout))
+	if err != nil {
+		return fmt.Errorf("server.shutdown_timeout invalid: %w", err)
+	}
+	if shutdownTimeout <= 0 {
+		return errors.New("server.shutdown_timeout must be > 0")
+	}
+	c.Server.ShutdownTimeoutDur = shutdownTimeout
+
 	if c.Server.MaxHeaderBytes <= 0 {
 		return errors.New("server.max_header_bytes must be > 0")
 	}
@@ -278,18 +294,10 @@ func (c *Config) Validate() error {
 	if strings.TrimSpace(c.Storage.DataDir) == "" {
 		return errors.New("storage.data_dir is required")
 	}
-	if err := ensureWritableDir(c.Storage.DataDir); err != nil {
-		return fmt.Errorf("storage.data_dir not writable: %w", err)
-	}
-	encKey, err := ensureEncryptionKeyInDataDir(c.Storage.DataDir)
-	if err != nil {
-		return fmt.Errorf("storage encryption key setup failed: %w", err)
-	}
-	if len(encKey) != 32 {
-		return fmt.Errorf("storage encryption key must decode to 32 bytes, got %d", len(encKey))
-	}
-	c.Storage.EncryptionKeyBytes = encKey
-
+	// NOTE: directory creation + encryption key provisioning (with auto-gen on empty dir)
+	// moved to PrepareDataDir() to keep Validate() free of filesystem side effects.
+	// Callers (server startup, tests) must invoke PrepareDataDir after successful Validate/Load
+	// if they need EncryptionKeyBytes populated and data dir ensured.
 	prefixes, err := parseAllowedPrefixes(c.Security.AllowedIPs)
 	if err != nil {
 		return fmt.Errorf("security.allowed_ips invalid: %w", err)
@@ -326,6 +334,31 @@ func (c *Config) Validate() error {
 	return nil
 }
 
+// PrepareDataDir performs the filesystem side effects that were previously inside Validate:
+// ensures the data dir is creatable/writable (via probe), and ensures the encryption key
+// file exists at data_dir/metadata.key (auto-generating a fresh one only for a truly empty dir).
+// It populates Storage.EncryptionKeyBytes. This keeps Validate pure (checks + duration/size
+// parsing only). Must be called after Load/Validate (or on a manually built Config) before
+// constructing a FilesystemStore that needs the key. Idempotent for subsequent calls if key
+// already present.
+func (c *Config) PrepareDataDir() error {
+	if strings.TrimSpace(c.Storage.DataDir) == "" {
+		return errors.New("storage.data_dir is required")
+	}
+	if err := ensureWritableDir(c.Storage.DataDir); err != nil {
+		return fmt.Errorf("storage.data_dir not writable: %w", err)
+	}
+	encKey, err := ensureEncryptionKeyInDataDir(c.Storage.DataDir)
+	if err != nil {
+		return fmt.Errorf("storage encryption key setup failed: %w", err)
+	}
+	if len(encKey) != 32 {
+		return fmt.Errorf("storage encryption key must decode to 32 bytes, got %d", len(encKey))
+	}
+	c.Storage.EncryptionKeyBytes = encKey
+	return nil
+}
+
 func ensureWritableDir(dir string) error {
 	if err := os.MkdirAll(dir, 0o755); err != nil {
 		return err
@@ -413,6 +446,11 @@ func parseHumanSize(raw string) (int64, error) {
 
 	size := int64(number * multiplier)
 	if size <= 0 {
+		if number > 0 {
+			// overflow or truncation from huge float (e.g. 1e20 * GiB); guard before
+			// passing surprising/negative limit downstream.
+			return 0, errors.New("size too large")
+		}
 		return 0, errors.New("calculated size must be > 0")
 	}
 	return size, nil
@@ -508,6 +546,9 @@ func (c *Config) applyEnvOverrides(prefix string) error {
 	if err := applyStringEnv(prefix+"SERVER_IDLE_TIMEOUT", &c.Server.IdleTimeout); err != nil {
 		return err
 	}
+	if err := applyStringEnv(prefix+"SERVER_SHUTDOWN_TIMEOUT", &c.Server.ShutdownTimeout); err != nil {
+		return err
+	}
 	if err := applyIntEnv(prefix+"SERVER_MAX_HEADER_BYTES", &c.Server.MaxHeaderBytes); err != nil {
 		return err
 	}
@@ -580,6 +621,10 @@ func (c *Config) applyEnvOverrides(prefix string) error {
 		return err
 	}
 
+	if err := applyBoolEnv(prefix+"SECURITY_HSTS_ENABLED", &c.Security.HSTSEnabled); err != nil {
+		return err
+	}
+
 	return nil
 }