From 76dcbe34291f7e53c68f10a93ec7b32bc749c24d Mon Sep 17 00:00:00 2001
From: Ludovic Fernandez <ldez@users.noreply.github.com>
Date: Mon, 23 Apr 2018 11:28:04 +0200
Subject: [PATCH] Fix error pages redirect and headers.

---
 middlewares/errorpages/error_pages.go      | 33 ++++++++++++++++++----
 middlewares/errorpages/error_pages_test.go |  6 ++--
 2 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/middlewares/errorpages/error_pages.go b/middlewares/errorpages/error_pages.go
index 49c218639..a2e9d426c 100644
--- a/middlewares/errorpages/error_pages.go
+++ b/middlewares/errorpages/error_pages.go
@@ -3,8 +3,10 @@ package errorpages
 import (
 	"bufio"
 	"bytes"
+	"fmt"
 	"net"
 	"net/http"
+	"net/url"
 	"strconv"
 	"strings"
 
@@ -75,8 +77,6 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, req *http.Request, next http.
 	recorder := newResponseRecorder(w)
 	next.ServeHTTP(recorder, req)
 
-	w.WriteHeader(recorder.GetCode())
-
 	// check the recorder code against the configured http status code ranges
 	for _, block := range h.httpCodeRanges {
 		if recorder.GetCode() >= block[0] && recorder.GetCode() <= block[1] {
@@ -88,20 +88,43 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, req *http.Request, next http.
 				query = strings.Replace(query, "{status}", strconv.Itoa(recorder.GetCode()), -1)
 			}
 
-			if newReq, err := http.NewRequest(http.MethodGet, h.backendURL+query, nil); err != nil {
+			pageReq, err := newRequest(h.backendURL + query)
+			if err != nil {
+				log.Error(err)
+				w.WriteHeader(recorder.GetCode())
 				w.Write([]byte(http.StatusText(recorder.GetCode())))
-			} else {
-				h.backendHandler.ServeHTTP(w, newReq)
+				return
 			}
+
+			utils.CopyHeaders(pageReq.Header, req.Header)
+			utils.CopyHeaders(w.Header(), recorder.Header())
+			w.WriteHeader(recorder.GetCode())
+			h.backendHandler.ServeHTTP(w, pageReq)
 			return
 		}
 	}
 
 	// did not catch a configured status code so proceed with the request
 	utils.CopyHeaders(w.Header(), recorder.Header())
+	w.WriteHeader(recorder.GetCode())
 	w.Write(recorder.GetBody().Bytes())
 }
 
+func newRequest(baseURL string) (*http.Request, error) {
+	u, err := url.Parse(baseURL)
+	if err != nil {
+		return nil, fmt.Errorf("error pages: error when parse URL: %v", err)
+	}
+
+	req, err := http.NewRequest(http.MethodGet, u.String(), nil)
+	if err != nil {
+		return nil, fmt.Errorf("error pages: error when create query: %v", err)
+	}
+
+	req.RequestURI = u.RequestURI()
+	return req, nil
+}
+
 type responseRecorder interface {
 	http.ResponseWriter
 	http.Flusher
diff --git a/middlewares/errorpages/error_pages_test.go b/middlewares/errorpages/error_pages_test.go
index 0ff70689b..2264dc336 100644
--- a/middlewares/errorpages/error_pages_test.go
+++ b/middlewares/errorpages/error_pages_test.go
@@ -65,7 +65,7 @@ func TestHandler(t *testing.T) {
 			errorPage:   &types.ErrorPage{Backend: "error", Query: "/{status}", Status: []string{"503-503"}},
 			backendCode: http.StatusServiceUnavailable,
 			backendErrorHandler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-				if r.URL.RequestURI() == "/"+strconv.Itoa(503) {
+				if r.RequestURI == "/503" {
 					fmt.Fprintln(w, "My 503 page.")
 				} else {
 					fmt.Fprintln(w, "Failed")
@@ -82,7 +82,7 @@ func TestHandler(t *testing.T) {
 			errorPage:   &types.ErrorPage{Backend: "error", Query: "/{status}", Status: []string{"503"}},
 			backendCode: http.StatusServiceUnavailable,
 			backendErrorHandler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-				if r.URL.RequestURI() == "/"+strconv.Itoa(503) {
+				if r.RequestURI == "/503" {
 					fmt.Fprintln(w, "My 503 page.")
 				} else {
 					fmt.Fprintln(w, "Failed")
@@ -318,6 +318,7 @@ func TestHandlerOldWayIntegration(t *testing.T) {
 			require.NoError(t, err)
 
 			handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				w.Header().Set("X-Foo", "bar")
 				w.WriteHeader(test.backendCode)
 				fmt.Fprintln(w, http.StatusText(test.backendCode))
 			})
@@ -330,6 +331,7 @@ func TestHandlerOldWayIntegration(t *testing.T) {
 			n.ServeHTTP(recorder, req)
 
 			test.validate(t, recorder)
+			assert.Equal(t, "bar", recorder.Header().Get("X-Foo"), "missing header")
 		})
 	}
 }