feat: use fiber/middleware/keyauth as starting point (#4)

authmeter.go

@@ -0,0 +1,119 @@
+package authmeter
+
+import (
+	"errors"
+	"net/url"
+	"strings"
+
+	"github.com/gofiber/fiber/v2"
+)
+
+// When there is no request of the key thrown ErrMissingOrMalformedAPIKey
+var ErrMissingOrMalformedAPIKey = errors.New("missing or malformed API Key")
+
+const (
+	query  = "query"
+	form   = "form"
+	param  = "param"
+	cookie = "cookie"
+)
+
+func New(config ...Config) fiber.Handler {
+	// Init config
+	cfg := configDefault(config...)
+
+	// Initialize
+	parts := strings.Split(cfg.KeyLookup, ":")
+	extractor := keyFromHeader(parts[1], cfg.AuthScheme)
+	switch parts[0] {
+	case query:
+		extractor = keyFromQuery(parts[1])
+	case form:
+		extractor = keyFromForm(parts[1])
+	case param:
+		extractor = keyFromParam(parts[1])
+	case cookie:
+		extractor = keyFromCookie(parts[1])
+	}
+
+	// Return middleware handler
+	return func(c *fiber.Ctx) error {
+		// Filter request to skip middleware
+		if cfg.Next != nil && cfg.Next(c) {
+			return c.Next()
+		}
+
+		// Extract and verify key
+		key, err := extractor(c)
+		if err != nil {
+			return cfg.ErrorHandler(c, err)
+		}
+
+		valid, err := cfg.Validator(c, key)
+
+		if err == nil && valid {
+			c.Locals(cfg.ContextKey, key)
+			return cfg.SuccessHandler(c)
+		}
+		return cfg.ErrorHandler(c, err)
+	}
+}
+
+// keyFromHeader returns a function that extracts api key from the request header.
+func keyFromHeader(header, authScheme string) func(c *fiber.Ctx) (string, error) {
+	return func(c *fiber.Ctx) (string, error) {
+		auth := c.Get(header)
+		l := len(authScheme)
+		if len(auth) > 0 && l == 0 {
+			return auth, nil
+		}
+		if len(auth) > l+1 && auth[:l] == authScheme {
+			return auth[l+1:], nil
+		}
+		return "", ErrMissingOrMalformedAPIKey
+	}
+}
+
+// keyFromQuery returns a function that extracts api key from the query string.
+func keyFromQuery(param string) func(c *fiber.Ctx) (string, error) {
+	return func(c *fiber.Ctx) (string, error) {
+		key := c.Query(param)
+		if key == "" {
+			return "", ErrMissingOrMalformedAPIKey
+		}
+		return key, nil
+	}
+}
+
+// keyFromForm returns a function that extracts api key from the form.
+func keyFromForm(param string) func(c *fiber.Ctx) (string, error) {
+	return func(c *fiber.Ctx) (string, error) {
+		key := c.FormValue(param)
+		if key == "" {
+			return "", ErrMissingOrMalformedAPIKey
+		}
+		return key, nil
+	}
+}
+
+// keyFromParam returns a function that extracts api key from the url param string.
+func keyFromParam(param string) func(c *fiber.Ctx) (string, error) {
+	return func(c *fiber.Ctx) (string, error) {
+		key, err := url.PathUnescape(c.Params(param))
+		if err != nil {
+			return "", ErrMissingOrMalformedAPIKey
+		}
+		return key, nil
+	}
+}
+
+// keyFromCookie returns a function that extracts api key from the named cookie.
+func keyFromCookie(name string) func(c *fiber.Ctx) (string, error) {
+	return func(c *fiber.Ctx) (string, error) {
+		key := c.Cookies(name)
+		if key == "" {
+			return "", ErrMissingOrMalformedAPIKey
+		}
+		return key, nil
+	}
+}