Adding Custom Header from claims (#532)

* Adding claim parameter mapping to custom header
* Fixing linting issue
* Fixing Linter reported usage of magic numbers
* Fixing Linter reported usage of magic numbers

Resolves #532
Co-authored-by: Althaf <althaf@spiatech.com>

middleware.go

@@ -415,8 +415,18 @@ func (r *oauthProxy) responseHeaderMiddleware(headers map[string]string) func(ht
 // identityHeadersMiddleware is responsible for add the authentication headers for the upstream
 func (r *oauthProxy) identityHeadersMiddleware(custom []string) func(http.Handler) http.Handler {
 	customClaims := make(map[string]string)
+
+	const minSliceLength int = 1
+
 	for _, x := range custom {
-		customClaims[x] = fmt.Sprintf("X-Auth-%s", toHeader(x))
+		xslices := strings.Split(x, "|")
+		x = xslices[0]
+
+		if len(xslices) > minSliceLength {
+			customClaims[x] = toHeader(xslices[1])
+		} else {
+			customClaims[x] = fmt.Sprintf("X-Auth-%s", toHeader(x))
+		}
 	}
 
 	cookieFilter := []string{r.config.CookieAccessName, r.config.CookieRefreshName}

middleware_test.go

@@ -1308,7 +1308,7 @@ func TestCustomHeadersHandler(t *testing.T) {
 			},
 		},
 		{
-			Match: []string{"given_name", "family_name"},
+			Match: []string{"given_name", "family_name", "preferred_username|Custom-Header"},
 			Request: fakeRequest{
 				URI:      fakeAuthAllURL,
 				HasToken: true,
@@ -1322,6 +1322,7 @@ func TestCustomHeadersHandler(t *testing.T) {
 				ExpectedProxyHeaders: map[string]string{
 					"X-Auth-Given-Name":  "Rohith",
 					"X-Auth-Family-Name": "Jayawardene",
+					"Custom-Header":      "rjayawardene",
 				},
 				ExpectedProxy: true,
 				ExpectedCode:  http.StatusOK,