add a custom error handler to key-auth middleware

middleware/key_auth.go

@@ -30,12 +30,19 @@ type (
 		// Validator is a function to validate key.
 		// Required.
 		Validator KeyAuthValidator
+
+		// ErrorHandler defines a function which is executed for an invalid key.
+		// It may be used to define a custom error.
+		ErrorHandler KeyAuthErrorHandler
 	}
 
 	// KeyAuthValidator defines a function to validate KeyAuth credentials.
 	KeyAuthValidator func(string, echo.Context) (bool, error)
 
 	keyExtractor func(echo.Context) (string, error)
+
+	// KeyAuthErrorHandler defines a function which is executed for an invalid key.
+	KeyAuthErrorHandler func(error, echo.Context) error
 )
 
 var (
@@ -95,10 +102,16 @@ func KeyAuthWithConfig(config KeyAuthConfig) echo.MiddlewareFunc {
 			// Extract and verify key
 			key, err := extractor(c)
 			if err != nil {
+				if config.ErrorHandler != nil {
+					return config.ErrorHandler(err, c)
+				}
 				return echo.NewHTTPError(http.StatusBadRequest, err.Error())
 			}
 			valid, err := config.Validator(key, c)
 			if err != nil {
+				if config.ErrorHandler != nil {
+					return config.ErrorHandler(err, c)
+				}
 				return &echo.HTTPError{
 					Code:     http.StatusUnauthorized,
 					Message:  "invalid key",

middleware/key_auth_test.go

@@ -1,75 +1,235 @@
 package middleware
 
 import (
+	"errors"
 	"net/http"
 	"net/http/httptest"
-	"net/url"
 	"strings"
 	"testing"
 
 	"github.com/labstack/echo/v4"
 	"github.com/stretchr/testify/assert"
 )
 
+func testKeyValidator(key string, c echo.Context) (bool, error) {
+	switch key {
+	case "valid-key":
+		return true, nil
+	case "error-key":
+		return false, errors.New("some user defined error")
+	default:
+		return false, nil
+	}
+}
+
 func TestKeyAuth(t *testing.T) {
+	handlerCalled := false
+	handler := func(c echo.Context) error {
+		handlerCalled = true
+		return c.String(http.StatusOK, "test")
+	}
+	middlewareChain := KeyAuth(testKeyValidator)(handler)
+
 	e := echo.New()
 	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	req.Header.Set(echo.HeaderAuthorization, "Bearer valid-key")
 	rec := httptest.NewRecorder()
 	c := e.NewContext(req, rec)
-	config := KeyAuthConfig{
-		Validator: func(key string, c echo.Context) (bool, error) {
-			return key == "valid-key", nil
-		},
-	}
-	h := KeyAuthWithConfig(config)(func(c echo.Context) error {
-		return c.String(http.StatusOK, "test")
-	})
 
-	assert := assert.New(t)
+	err := middlewareChain(c)
 
-	// Valid key
-	auth := DefaultKeyAuthConfig.AuthScheme + " " + "valid-key"
-	req.Header.Set(echo.HeaderAuthorization, auth)
-	assert.NoError(h(c))
+	assert.NoError(t, err)
+	assert.True(t, handlerCalled)
+}
 
-	// Invalid key
-	auth = DefaultKeyAuthConfig.AuthScheme + " " + "invalid-key"
-	req.Header.Set(echo.HeaderAuthorization, auth)
-	he := h(c).(*echo.HTTPError)
-	assert.Equal(http.StatusUnauthorized, he.Code)
+func TestKeyAuthWithConfig(t *testing.T) {
+	var testCases = []struct {
+		name                string
+		givenRequestFunc    func() *http.Request
+		givenRequest        func(req *http.Request)
+		whenConfig          func(conf *KeyAuthConfig)
+		expectHandlerCalled bool
+		expectError         string
+	}{
+		{
+			name: "ok, defaults, key from header",
+			givenRequest: func(req *http.Request) {
+				req.Header.Set(echo.HeaderAuthorization, "Bearer valid-key")
+			},
+			expectHandlerCalled: true,
+		},
+		{
+			name: "ok, custom skipper",
+			givenRequest: func(req *http.Request) {
+				req.Header.Set(echo.HeaderAuthorization, "Bearer error-key")
+			},
+			whenConfig: func(conf *KeyAuthConfig) {
+				conf.Skipper = func(context echo.Context) bool {
+					return true
+				}
+			},
+			expectHandlerCalled: true,
+		},
+		{
+			name: "nok, defaults, invalid key from header, Authorization: Bearer",
+			givenRequest: func(req *http.Request) {
+				req.Header.Set(echo.HeaderAuthorization, "Bearer invalid-key")
+			},
+			expectHandlerCalled: false,
+			expectError:         "code=401, message=Unauthorized",
+		},
+		{
+			name: "nok, defaults, invalid scheme in header",
+			givenRequest: func(req *http.Request) {
+				req.Header.Set(echo.HeaderAuthorization, "Bear valid-key")
+			},
+			expectHandlerCalled: false,
+			expectError:         "code=400, message=invalid key in the request header",
+		},
+		{
+			name:                "nok, defaults, missing header",
+			givenRequest:        func(req *http.Request) {},
+			expectHandlerCalled: false,
+			expectError:         "code=400, message=missing key in request header",
+		},
+		{
+			name: "ok, custom key lookup, header",
+			givenRequest: func(req *http.Request) {
+				req.Header.Set("API-Key", "valid-key")
+			},
+			whenConfig: func(conf *KeyAuthConfig) {
+				conf.KeyLookup = "header:API-Key"
+			},
+			expectHandlerCalled: true,
+		},
+		{
+			name: "nok, custom key lookup, missing header",
+			givenRequest: func(req *http.Request) {
+			},
+			whenConfig: func(conf *KeyAuthConfig) {
+				conf.KeyLookup = "header:API-Key"
+			},
+			expectHandlerCalled: false,
+			expectError:         "code=400, message=missing key in request header",
+		},
+		{
+			name: "ok, custom key lookup, query",
+			givenRequest: func(req *http.Request) {
+				q := req.URL.Query()
+				q.Add("key", "valid-key")
+				req.URL.RawQuery = q.Encode()
+			},
+			whenConfig: func(conf *KeyAuthConfig) {
+				conf.KeyLookup = "query:key"
+			},
+			expectHandlerCalled: true,
+		},
+		{
+			name: "nok, custom key lookup, missing query param",
+			whenConfig: func(conf *KeyAuthConfig) {
+				conf.KeyLookup = "query:key"
+			},
+			expectHandlerCalled: false,
+			expectError:         "code=400, message=missing key in the query string",
+		},
+		{
+			name: "ok, custom key lookup, form",
+			givenRequestFunc: func() *http.Request {
+				req := httptest.NewRequest(http.MethodPost, "/", strings.NewReader("key=valid-key"))
+				req.Header.Set(echo.HeaderContentType, echo.MIMEApplicationForm)
+				return req
+			},
+			whenConfig: func(conf *KeyAuthConfig) {
+				conf.KeyLookup = "form:key"
+			},
+			expectHandlerCalled: true,
+		},
+		{
+			name: "nok, custom key lookup, missing key in form",
+			givenRequestFunc: func() *http.Request {
+				req := httptest.NewRequest(http.MethodPost, "/", strings.NewReader("xxx=valid-key"))
+				req.Header.Set(echo.HeaderContentType, echo.MIMEApplicationForm)
+				return req
+			},
+			whenConfig: func(conf *KeyAuthConfig) {
+				conf.KeyLookup = "form:key"
+			},
+			expectHandlerCalled: false,
+			expectError:         "code=400, message=missing key in the form",
+		},
+		{
+			name: "nok, custom errorHandler, error from extractor",
+			whenConfig: func(conf *KeyAuthConfig) {
+				conf.KeyLookup = "header:token"
+				conf.ErrorHandler = func(err error, context echo.Context) error {
+					httpError := echo.NewHTTPError(http.StatusTeapot, "custom")
+					httpError.Internal = err
+					return httpError
+				}
+			},
+			expectHandlerCalled: false,
+			expectError:         "code=418, message=custom, internal=missing key in request header",
+		},
+		{
+			name: "nok, custom errorHandler, error from validator",
+			givenRequest: func(req *http.Request) {
+				req.Header.Set(echo.HeaderAuthorization, "Bearer error-key")
+			},
+			whenConfig: func(conf *KeyAuthConfig) {
+				conf.ErrorHandler = func(err error, context echo.Context) error {
+					httpError := echo.NewHTTPError(http.StatusTeapot, "custom")
+					httpError.Internal = err
+					return httpError
+				}
+			},
+			expectHandlerCalled: false,
+			expectError:         "code=418, message=custom, internal=some user defined error",
+		},
+		{
+			name: "nok, defaults, error from validator",
+			givenRequest: func(req *http.Request) {
+				req.Header.Set(echo.HeaderAuthorization, "Bearer error-key")
+			},
+			whenConfig:          func(conf *KeyAuthConfig) {},
+			expectHandlerCalled: false,
+			expectError:         "code=401, message=invalid key, internal=some user defined error",
+		},
+	}
 
-	// Missing Authorization header
-	req.Header.Del(echo.HeaderAuthorization)
-	he = h(c).(*echo.HTTPError)
-	assert.Equal(http.StatusBadRequest, he.Code)
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			handlerCalled := false
+			handler := func(c echo.Context) error {
+				handlerCalled = true
+				return c.String(http.StatusOK, "test")
+			}
+			config := KeyAuthConfig{
+				Validator: testKeyValidator,
+			}
+			if tc.whenConfig != nil {
+				tc.whenConfig(&config)
+			}
+			middlewareChain := KeyAuthWithConfig(config)(handler)
 
-	// Key from custom header
-	config.KeyLookup = "header:API-Key"
-	h = KeyAuthWithConfig(config)(func(c echo.Context) error {
-		return c.String(http.StatusOK, "test")
-	})
-	req.Header.Set("API-Key", "valid-key")
-	assert.NoError(h(c))
+			e := echo.New()
+			req := httptest.NewRequest(http.MethodGet, "/", nil)
+			if tc.givenRequestFunc != nil {
+				req = tc.givenRequestFunc()
+			}
+			if tc.givenRequest != nil {
+				tc.givenRequest(req)
+			}
+			rec := httptest.NewRecorder()
+			c := e.NewContext(req, rec)
 
-	// Key from query string
-	config.KeyLookup = "query:key"
-	h = KeyAuthWithConfig(config)(func(c echo.Context) error {
-		return c.String(http.StatusOK, "test")
-	})
-	q := req.URL.Query()
-	q.Add("key", "valid-key")
-	req.URL.RawQuery = q.Encode()
-	assert.NoError(h(c))
+			err := middlewareChain(c)
 
-	// Key from form
-	config.KeyLookup = "form:key"
-	h = KeyAuthWithConfig(config)(func(c echo.Context) error {
-		return c.String(http.StatusOK, "test")
-	})
-	f := make(url.Values)
-	f.Set("key", "valid-key")
-	req = httptest.NewRequest(http.MethodPost, "/", strings.NewReader(f.Encode()))
-	req.Header.Set(echo.HeaderContentType, echo.MIMEApplicationForm)
-	c = e.NewContext(req, rec)
-	assert.NoError(h(c))
+			assert.Equal(t, tc.expectHandlerCalled, handlerCalled)
+			if tc.expectError != "" {
+				assert.EqualError(t, err, tc.expectError)
+			} else {
+				assert.NoError(t, err)
+			}
+		})
+	}
 }