package customerrors import ( "context" "fmt" "io" "net/http" "net/http/httptest" "net/http/httptrace" "net/textproto" "testing" "github.com/stretchr/testify/assert" "github.com/stretchr/testify/require" "github.com/traefik/traefik/v3/pkg/config/dynamic" "github.com/traefik/traefik/v3/pkg/testhelpers" ) func TestHandler(t *testing.T) { testCases := []struct { desc string errorPage *dynamic.ErrorPage backendCode int backendErrorHandler http.HandlerFunc validate func(t *testing.T, recorder *httptest.ResponseRecorder) }{ { desc: "no error", errorPage: &dynamic.ErrorPage{Service: "error", Query: "/test", Status: []string{"500-501", "503-599"}}, backendCode: http.StatusOK, backendErrorHandler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { _, _ = fmt.Fprintln(w, "My error page.") }), validate: func(t *testing.T, recorder *httptest.ResponseRecorder) { t.Helper() assert.Equal(t, http.StatusOK, recorder.Code, "HTTP status") assert.Contains(t, recorder.Body.String(), http.StatusText(http.StatusOK)) }, }, { desc: "no error, but not a 200", errorPage: &dynamic.ErrorPage{Service: "error", Query: "/test", Status: []string{"500-501", "503-599"}}, backendCode: http.StatusPartialContent, backendErrorHandler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { _, _ = fmt.Fprintln(w, "My error page.") }), validate: func(t *testing.T, recorder *httptest.ResponseRecorder) { t.Helper() assert.Equal(t, http.StatusPartialContent, recorder.Code, "HTTP status") assert.Contains(t, recorder.Body.String(), http.StatusText(http.StatusPartialContent)) }, }, { desc: "a 304, so no Write called", errorPage: &dynamic.ErrorPage{Service: "error", Query: "/test", Status: []string{"500-501", "503-599"}}, backendCode: http.StatusNotModified, backendErrorHandler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { _, _ = fmt.Fprintln(w, "whatever, should not be called") }), validate: func(t *testing.T, recorder *httptest.ResponseRecorder) { t.Helper() assert.Equal(t, http.StatusNotModified, recorder.Code, "HTTP status") assert.Contains(t, recorder.Body.String(), "") }, }, { desc: "in the range", errorPage: &dynamic.ErrorPage{Service: "error", Query: "/test", Status: []string{"500-501", "503-599"}}, backendCode: http.StatusInternalServerError, backendErrorHandler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { _, _ = fmt.Fprintln(w, "My error page.") }), validate: func(t *testing.T, recorder *httptest.ResponseRecorder) { t.Helper() assert.Equal(t, http.StatusInternalServerError, recorder.Code, "HTTP status") assert.Contains(t, recorder.Body.String(), "My error page.") }, }, { desc: "not in the range", errorPage: &dynamic.ErrorPage{Service: "error", Query: "/test", Status: []string{"500-501", "503-599"}}, backendCode: http.StatusBadGateway, backendErrorHandler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { _, _ = fmt.Fprintln(w, "My error page.") }), validate: func(t *testing.T, recorder *httptest.ResponseRecorder) { t.Helper() assert.Equal(t, http.StatusBadGateway, recorder.Code, "HTTP status") assert.Contains(t, recorder.Body.String(), http.StatusText(http.StatusBadGateway)) }, }, { desc: "query replacement", errorPage: &dynamic.ErrorPage{Service: "error", Query: "/{status}", Status: []string{"503-503"}}, backendCode: http.StatusServiceUnavailable, backendErrorHandler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { if r.RequestURI != "/503" { return } _, _ = fmt.Fprintln(w, "My 503 page.") }), validate: func(t *testing.T, recorder *httptest.ResponseRecorder) { t.Helper() assert.Equal(t, http.StatusServiceUnavailable, recorder.Code, "HTTP status") assert.Contains(t, recorder.Body.String(), "My 503 page.") }, }, { desc: "single code and query replacement", errorPage: &dynamic.ErrorPage{Service: "error", Query: "/{status}", Status: []string{"503"}}, backendCode: http.StatusServiceUnavailable, backendErrorHandler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { if r.RequestURI != "/503" { return } _, _ = fmt.Fprintln(w, "My 503 page.") }), validate: func(t *testing.T, recorder *httptest.ResponseRecorder) { t.Helper() assert.Equal(t, http.StatusServiceUnavailable, recorder.Code, "HTTP status") assert.Contains(t, recorder.Body.String(), "My 503 page.") }, }, { desc: "forward request host header", errorPage: &dynamic.ErrorPage{Service: "error", Query: "/test", Status: []string{"503"}}, backendCode: http.StatusServiceUnavailable, backendErrorHandler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { _, _ = fmt.Fprintln(w, r.Host) }), validate: func(t *testing.T, recorder *httptest.ResponseRecorder) { t.Helper() assert.Equal(t, http.StatusServiceUnavailable, recorder.Code, "HTTP status") assert.Contains(t, recorder.Body.String(), "localhost") }, }, { desc: "full query replacement", errorPage: &dynamic.ErrorPage{Service: "error", Query: "/?status={status}&url={url}", Status: []string{"503"}}, backendCode: http.StatusServiceUnavailable, backendErrorHandler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { if r.RequestURI != "/?status=503&url=http%3A%2F%2Flocalhost%2Ftest%3Ffoo%3Dbar%26baz%3Dbuz" { t.Log(r.RequestURI) return } _, _ = fmt.Fprintln(w, "My 503 page.") }), validate: func(t *testing.T, recorder *httptest.ResponseRecorder) { t.Helper() assert.Equal(t, http.StatusServiceUnavailable, recorder.Code, "HTTP status") assert.Contains(t, recorder.Body.String(), "My 503 page.") }, }, } for _, test := range testCases { t.Run(test.desc, func(t *testing.T) { t.Parallel() serviceBuilderMock := &mockServiceBuilder{handler: test.backendErrorHandler} handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { w.WriteHeader(test.backendCode) if test.backendCode == http.StatusNotModified { return } _, _ = fmt.Fprintln(w, http.StatusText(test.backendCode)) }) errorPageHandler, err := New(context.Background(), handler, *test.errorPage, serviceBuilderMock, "test") require.NoError(t, err) req := testhelpers.MustNewRequest(http.MethodGet, "http://localhost/test?foo=bar&baz=buz", nil) recorder := httptest.NewRecorder() errorPageHandler.ServeHTTP(recorder, req) test.validate(t, recorder) }) } } // This test is an adapted version of net/http/httputil.Test1xxResponses test. func Test1xxResponses(t *testing.T) { next := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { h := w.Header() h.Add("Link", "; rel=preload; as=style") h.Add("Link", "; rel=preload; as=script") w.WriteHeader(http.StatusEarlyHints) h.Add("Link", "; rel=preload; as=script") w.WriteHeader(http.StatusProcessing) h.Add("User-Agent", "foobar") _, _ = w.Write([]byte("Hello")) w.WriteHeader(http.StatusBadGateway) }) serviceBuilderMock := &mockServiceBuilder{handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { _, _ = fmt.Fprintln(w, "My error page.") })} config := dynamic.ErrorPage{Service: "error", Query: "/", Status: []string{"200"}} errorPageHandler, err := New(context.Background(), next, config, serviceBuilderMock, "test") require.NoError(t, err) server := httptest.NewServer(errorPageHandler) t.Cleanup(server.Close) frontendClient := server.Client() checkLinkHeaders := func(t *testing.T, expected, got []string) { t.Helper() if len(expected) != len(got) { t.Errorf("Expected %d link headers; got %d", len(expected), len(got)) } for i := range expected { if i >= len(got) { t.Errorf("Expected %q link header; got nothing", expected[i]) continue } if expected[i] != got[i] { t.Errorf("Expected %q link header; got %q", expected[i], got[i]) } } } var respCounter uint8 trace := &httptrace.ClientTrace{ Got1xxResponse: func(code int, header textproto.MIMEHeader) error { switch code { case http.StatusEarlyHints: checkLinkHeaders(t, []string{"; rel=preload; as=style", "; rel=preload; as=script"}, header["Link"]) case http.StatusProcessing: checkLinkHeaders(t, []string{"; rel=preload; as=style", "; rel=preload; as=script", "; rel=preload; as=script"}, header["Link"]) default: t.Error("Unexpected 1xx response") } respCounter++ return nil }, } req, _ := http.NewRequestWithContext(httptrace.WithClientTrace(context.Background(), trace), http.MethodGet, server.URL, nil) res, err := frontendClient.Do(req) assert.NoError(t, err) defer res.Body.Close() if respCounter != 2 { t.Errorf("Expected 2 1xx responses; got %d", respCounter) } checkLinkHeaders(t, []string{"; rel=preload; as=style", "; rel=preload; as=script", "; rel=preload; as=script"}, res.Header["Link"]) body, _ := io.ReadAll(res.Body) assert.Equal(t, "My error page.\n", string(body)) } type mockServiceBuilder struct { handler http.Handler } func (m *mockServiceBuilder) BuildHTTP(_ context.Context, _ string) (http.Handler, error) { return m.handler, nil }