Fix panic when path is empty (TykTechnologies#3243)

Fixes TykTechnologies#3242

gateway/mw_request_signing.go

@@ -83,10 +83,9 @@ func (s *RequestSigning) getRequestPath(r *http.Request) string {
 	} else {
 		if s.Spec.Proxy.StripListenPath {
 			path = s.Spec.StripListenPath(r, path)
-			if path[:1] != "/" {
+			if !strings.HasPrefix(path, "/") {
 				path = "/" + path
 			}
-
 		}
 	}
 

gateway/mw_request_signing_test.go

@@ -552,6 +552,12 @@ func TestRequestSigning_getRequestPath(t *testing.T) {
 	t.Run("StripListenPath=true", func(t *testing.T) {
 		api.Proxy.StripListenPath = true
 		assert.Equal(t, "/get?param1=value1", rs.getRequestPath(req))
+
+		t.Run("path is empty", func(t *testing.T) {
+			reqWithEmptyPath, _ := http.NewRequest(http.MethodGet, "http://example.com/test/", nil)
+			assert.Equal(t, "/", rs.getRequestPath(reqWithEmptyPath))
+		})
+
 		api.Proxy.StripListenPath = false
 	})