New() — fiber Function Reference

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

Function go FiberCore Adapters calls 2

Entity Profile

FiberCore→ Adapters→ New() — fiber Function Reference

Dependency Diagram

graph TD
  ff55d799_cd38_2358_2bd9_9d94fb74dfed["New()"]
  e660d89f_158e_a31e_1a40_def5af9d743a["etag.go"]
  ff55d799_cd38_2358_2bd9_9d94fb74dfed -->|defined in| e660d89f_158e_a31e_1a40_def5af9d743a
  8fcfa90d_475d_4083_86aa_d99375e797df["GenerateWeak()"]
  ff55d799_cd38_2358_2bd9_9d94fb74dfed -->|calls| 8fcfa90d_475d_4083_86aa_d99375e797df
  bf507e91_53f1_f386_5bf6_f1e81b6cd10b["Generate()"]
  ff55d799_cd38_2358_2bd9_9d94fb74dfed -->|calls| bf507e91_53f1_f386_5bf6_f1e81b6cd10b
  style ff55d799_cd38_2358_2bd9_9d94fb74dfed fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

middleware/etag/etag.go lines 44–117

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

	normalizedHeaderETag := []byte("Etag")

	// 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()
		}

		// Return err if next handler returns one
		if err := c.Next(); err != nil {
			return err
		}

		// Don't generate ETags for invalid responses
		if c.Response().StatusCode() != fiber.StatusOK {
			return nil
		}
		body := c.Response().Body()
		// Skips ETag if no response body is present
		if len(body) == 0 {
			return nil
		}
		// Skip ETag if header is already present
		if c.Response().Header.PeekBytes(normalizedHeaderETag) != nil {
			return nil
		}

		bodyLength := len(body)
		if bodyLength > math.MaxUint32 {
			return c.SendStatus(fiber.StatusRequestEntityTooLarge)
		}

		var etag []byte
		if cfg.Weak {
			etag = GenerateWeak(body)
		} else {
			etag = Generate(body)
		}

		// Get ETag header from request
		clientEtag := c.Request().Header.Peek(fiber.HeaderIfNoneMatch)

		// Check if client's ETag is weak
		if bytes.HasPrefix(clientEtag, weakPrefix) {
			// Check if server's ETag is weak
			if bytes.Equal(clientEtag[2:], etag) || bytes.Equal(clientEtag[2:], etag[2:]) {
				// W/1 == 1 || W/1 == W/1
				c.RequestCtx().ResetBody()

				return c.SendStatus(fiber.StatusNotModified)
			}
			// W/1 != W/2 || W/1 != 2
			c.Response().Header.SetCanonical(normalizedHeaderETag, etag)

			return nil
		}

		if bytes.Contains(clientEtag, etag) {
			// 1 == 1
			c.RequestCtx().ResetBody()

			return c.SendStatus(fiber.StatusNotModified)
		}
		// 1 != 2
		c.Response().Header.SetCanonical(normalizedHeaderETag, etag)

		return nil
	}
}