New() — fiber Function Reference

Architecture documentation for the New() function in cors.go from the fiber codebase.

Function go FiberCore Adapters calls 3

Entity Profile

FiberCore→ Adapters→ New() — fiber Function Reference

Dependency Diagram

graph TD
  54c44c1d_58d3_cf2b_fb3c_32185916a214["New()"]
  44855f15_c1df_ce6b_695f_24aa3cc78dd0["cors.go"]
  54c44c1d_58d3_cf2b_fb3c_32185916a214 -->|defined in| 44855f15_c1df_ce6b_695f_24aa3cc78dd0
  498669f0_8840_add2_a290_e883a503056e["isOriginSerializedOrNull()"]
  54c44c1d_58d3_cf2b_fb3c_32185916a214 -->|calls| 498669f0_8840_add2_a290_e883a503056e
  b209eb6c_c11b_418b_1c48_f62f26b25ccc["setSimpleHeaders()"]
  54c44c1d_58d3_cf2b_fb3c_32185916a214 -->|calls| b209eb6c_c11b_418b_1c48_f62f26b25ccc
  79dd7047_b0c9_9b9a_33c3_fb5b58b10888["setPreflightHeaders()"]
  54c44c1d_58d3_cf2b_fb3c_32185916a214 -->|calls| 79dd7047_b0c9_9b9a_33c3_fb5b58b10888
  style 54c44c1d_58d3_cf2b_fb3c_32185916a214 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

middleware/cors/cors.go lines 27–211

func New(config ...Config) fiber.Handler {
	// Set default config
	cfg := ConfigDefault

	// Override config if provided
	if len(config) > 0 {
		cfg = config[0]

		// Set default values
		if len(cfg.AllowMethods) == 0 {
			cfg.AllowMethods = ConfigDefault.AllowMethods
		}
	}

	redactValues := !cfg.DisableValueRedaction

	maskValue := func(value string) string {
		if redactValues {
			return redactedValue
		}
		return value
	}

	// Warning logs if both AllowOrigins and AllowOriginsFunc are set
	if len(cfg.AllowOrigins) > 0 && cfg.AllowOriginsFunc != nil {
		log.Warn("[CORS] Both 'AllowOrigins' and 'AllowOriginsFunc' have been defined.")
	}

	// allowOrigins is a slice of strings that contains the allowed origins
	// defined in the 'AllowOrigins' configuration.
	allowOrigins := []string{}
	allowSubOrigins := []subdomain{}

	// Validate and normalize static AllowOrigins
	allowAllOrigins := len(cfg.AllowOrigins) == 0 && cfg.AllowOriginsFunc == nil
	for _, origin := range cfg.AllowOrigins {
		if origin == "*" {
			allowAllOrigins = true
			break
		}

		trimmedOrigin := utils.TrimSpace(origin)
		if before, after, found := strings.Cut(trimmedOrigin, "://*."); found {
			withoutWildcard := before + "://" + after
			isValid, normalizedOrigin := normalizeOrigin(withoutWildcard)
			if !isValid {
				panic("[CORS] Invalid origin format in configuration: " + maskValue(trimmedOrigin))
			}
			scheme, host, ok := strings.Cut(normalizedOrigin, "://")
			if !ok {
				panic("[CORS] Invalid origin format after normalization:" + maskValue(trimmedOrigin))
			}
			sd := subdomain{prefix: scheme + "://", suffix: host}
			allowSubOrigins = append(allowSubOrigins, sd)
		} else {
			isValid, normalizedOrigin := normalizeOrigin(trimmedOrigin)
			if !isValid {
				panic("[CORS] Invalid origin format in configuration: " + maskValue(trimmedOrigin))
			}
			allowOrigins = append(allowOrigins, normalizedOrigin)
		}
	}

	// Validate CORS credentials configuration
	if cfg.AllowCredentials && allowAllOrigins {
		panic("[CORS] Configuration error: When 'AllowCredentials' is set to true, 'AllowOrigins' cannot contain a wildcard origin '*'. Please specify allowed origins explicitly or adjust 'AllowCredentials' setting.")
	}

	// Warn if allowAllOrigins is set to true and AllowOriginsFunc is defined
	if allowAllOrigins && cfg.AllowOriginsFunc != nil {
		log.Warn("[CORS] 'AllowOrigins' is set to allow all origins, 'AllowOriginsFunc' will not be used.")
	}

	// Convert int to string
	maxAge := strconv.Itoa(cfg.MaxAge)

	// Return new handler
	return func(c fiber.Ctx) error {
		// Don't execute middleware if Next returns true
		if cfg.Next != nil && cfg.Next(c) {
			return c.Next()