Added method override middleware

Signed-off-by: Vishal Rana <vr@labstack.com>

middleware/basic_auth.go

@@ -0,0 +1,69 @@
+package middleware
+
+import (
+	"encoding/base64"
+	"net/http"
+
+	"github.com/labstack/echo"
+)
+
+type (
+	// BasicAuthConfig defines the config for HTTP basic auth middleware.
+	BasicAuthConfig struct {
+		// Validator is the function to validate basic auth credentials.
+		Validator BasicAuthValidator
+	}
+
+	// BasicAuthValidator defines a function to validate basic auth credentials.
+	BasicAuthValidator func(string, string) bool
+)
+
+const (
+	basic = "Basic"
+)
+
+var (
+	// DefaultBasicAuthConfig is the default basic auth middleware config.
+	DefaultBasicAuthConfig = BasicAuthConfig{}
+)
+
+// BasicAuth returns an HTTP basic auth middleware.
+//
+// For valid credentials it calls the next handler.
+// For invalid credentials, it sends "401 - Unauthorized" response.
+// For empty or invalid `Authorization` header, it sends "400 - Bad Request" response.
+func BasicAuth(fn BasicAuthValidator) echo.MiddlewareFunc {
+	c := DefaultBasicAuthConfig
+	c.Validator = fn
+	return BasicAuthWithConfig(c)
+}
+
+// BasicAuthWithConfig returns an HTTP basic auth middleware from config.
+// See `BasicAuth()`.
+func BasicAuthWithConfig(config BasicAuthConfig) echo.MiddlewareFunc {
+	return func(next echo.HandlerFunc) echo.HandlerFunc {
+		return func(c echo.Context) error {
+			auth := c.Request().Header().Get(echo.HeaderAuthorization)
+			l := len(basic)
+
+			if len(auth) > l+1 && auth[:l] == basic {
+				b, err := base64.StdEncoding.DecodeString(auth[l+1:])
+				if err != nil {
+					return err
+				}
+				cred := string(b)
+				for i := 0; i < len(cred); i++ {
+					if cred[i] == ':' {
+						// Verify credentials
+						if config.Validator(cred[:i], cred[i+1:]) {
+							return next(c)
+						}
+						c.Response().Header().Set(echo.HeaderWWWAuthenticate, basic+" realm=Restricted")
+						return echo.ErrUnauthorized
+					}
+				}
+			}
+			return echo.NewHTTPError(http.StatusBadRequest, "invalid basic-auth authorization header="+auth)
+		}
+	}
+}