net/http: redirect handlers from mux.Handler() shouldn't clear the query string

R=bradfitz, alberto.garcia.hierro, rsc, adg
CC=golang-dev
https://golang.org/cl/7099045

src/pkg/net/http/serve_test.go

@@ -277,6 +277,7 @@ var serveMuxRegister = []struct {
 	{"/search", serve(201)},
 	{"codesearch.google.com/search", serve(202)},
 	{"codesearch.google.com/", serve(203)},
+	{"example.com/", HandlerFunc(checkQueryStringHandler)},
 }
 
 // serve returns a handler that sends a response with the given code.
@@ -286,6 +287,21 @@ func serve(code int) HandlerFunc {
 	}
 }
 
+// checkQueryStringHandler checks if r.URL.RawQuery has the same value
+// as the URL excluding the scheme and the query string and sends 200
+// response code if it is, 500 otherwise.
+func checkQueryStringHandler(w ResponseWriter, r *Request) {
+	u := *r.URL
+	u.Scheme = "http"
+	u.Host = r.Host
+	u.RawQuery = ""
+	if "http://"+r.URL.RawQuery == u.String() {
+		w.WriteHeader(200)
+	} else {
+		w.WriteHeader(500)
+	}
+}
+
 var serveMuxTests = []struct {
 	method  string
 	host    string
@@ -344,6 +360,61 @@ func TestServeMuxHandler(t *testing.T) {
 	}
 }
 
+var serveMuxTests2 = []struct {
+	method  string
+	host    string
+	url     string
+	code    int
+	redirOk bool
+}{
+	{"GET", "google.com", "/", 404, false},
+	{"GET", "example.com", "/test/?example.com/test/", 200, false},
+	{"GET", "example.com", "test/?example.com/test/", 200, true},
+}
+
+// TestServeMuxHandlerRedirects tests that automatic redirects generated by
+// mux.Handler() shouldn't clear the request's query string.
+func TestServeMuxHandlerRedirects(t *testing.T) {
+	mux := NewServeMux()
+	for _, e := range serveMuxRegister {
+		mux.Handle(e.pattern, e.h)
+	}
+
+	for _, tt := range serveMuxTests2 {
+		tries := 1
+		turl := tt.url
+		for tries > 0 {
+			u, e := url.Parse(turl)
+			if e != nil {
+				t.Fatal(e)
+			}
+			r := &Request{
+				Method: tt.method,
+				Host:   tt.host,
+				URL:    u,
+			}
+			h, _ := mux.Handler(r)
+			rr := httptest.NewRecorder()
+			h.ServeHTTP(rr, r)
+			if rr.Code != 301 {
+				if rr.Code != tt.code {
+					t.Errorf("%s %s %s = %d, want %d", tt.method, tt.host, tt.url, rr.Code, tt.code)
+				}
+				break
+			}
+			if !tt.redirOk {
+				t.Errorf("%s %s %s, unexpected redirect", tt.method, tt.host, tt.url)
+				break
+			}
+			turl = rr.HeaderMap.Get("Location")
+			tries--
+		}
+		if tries < 0 {
+			t.Errorf("%s %s %s, too many redirects", tt.method, tt.host, tt.url)
+		}
+	}
+}
+
 // Tests for http://code.google.com/p/go/issues/detail?id=900
 func TestMuxRedirectLeadingSlashes(t *testing.T) {
 	paths := []string{"//foo.txt", "///foo.txt", "/../../foo.txt"}

src/pkg/net/http/server.go

@@ -1448,7 +1448,9 @@ func (mux *ServeMux) Handler(r *Request) (h Handler, pattern string) {
 	if r.Method != "CONNECT" {
 		if p := cleanPath(r.URL.Path); p != r.URL.Path {
 			_, pattern = mux.handler(r.Host, p)
-			return RedirectHandler(p, StatusMovedPermanently), pattern
+			url := *r.URL
+			url.Path = p
+			return RedirectHandler(url.String(), StatusMovedPermanently), pattern
 		}
 	}