Fix for #659.

middleware/rewrite/rewrite.go

@@ -5,6 +5,7 @@ package rewrite
 import (
 	"fmt"
 	"net/http"
+	"net/url"
 	"path"
 	"path/filepath"
 	"regexp"
@@ -165,7 +166,17 @@ func (r *ComplexRule) Rewrite(fs http.FileSystem, req *http.Request) (re Result)
 			return
 		default:
 			// set regexp match variables {1}, {2} ...
+
+			// url escaped values of ? and #.
+			q, f := url.QueryEscape("?"), url.QueryEscape("#")
+
 			for i := 1; i < len(matches); i++ {
+				// Special case of unescaped # and ? by stdlib regexp.
+				// Reverse the unescape.
+				if strings.ContainsAny(matches[i], "?#") {
+					matches[i] = strings.NewReplacer("?", q, "#", f).Replace(matches[i])
+				}
+
 				replacer.Set(fmt.Sprint(i), matches[i])
 			}
 		}

middleware/rewrite/rewrite_test.go

@@ -34,6 +34,7 @@ func TestRewrite(t *testing.T) {
 		{"/reggrp", `/ad/([0-9]+)([a-z]*)`, "/a{1}/{2}", ""},
 		{"/reg2grp", `(.*)`, "/{1}", ""},
 		{"/reg3grp", `(.*)/(.*)/(.*)`, "/{1}{2}{3}", ""},
+		{"/hashtest", "(.*)", "/{1}", ""},
 	}
 
 	for _, regexpRule := range regexps {
@@ -90,6 +91,9 @@ func TestRewrite(t *testing.T) {
 		{"/reg2grp/ad/124abc", "/ad/124abc"},
 		{"/reg3grp/ad/aa/66", "/adaa66"},
 		{"/reg3grp/ad612/n1n/ab", "/ad612n1nab"},
+		{"/hashtest/a%20%23%20test", "/a%20%23%20test"},
+		{"/hashtest/a%20%3F%20test", "/a%20%3F%20test"},
+		{"/hashtest/a%20%3F%23test", "/a%20%3F%23test"},
 	}
 
 	for i, test := range tests {
@@ -154,6 +158,6 @@ func TestRewrite(t *testing.T) {
 }
 
 func urlPrinter(w http.ResponseWriter, r *http.Request) (int, error) {
-	fmt.Fprintf(w, r.URL.String())
+	fmt.Fprint(w, r.URL.String())
 	return 0, nil
 }