net/http: strip port from host in mux Handler

This change strips the port in mux.Handler before attempting to
match handlers and adds a test for a request with port.

CONNECT requests continue to use the original path and port.

Fixes #10463

Change-Id: Iff3a2ca2b7f1d884eca05a7262ad6b7dffbcc30f
Reviewed-on: https://go-review.googlesource.com/38194
Reviewed-by: Brad Fitzpatrick <[email protected]>
Run-TryBot: Brad Fitzpatrick <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>

Author: kennygrant

src/net/http/serve_test.go

@@ -337,6 +337,7 @@ var serveMuxTests = []struct {
 	{"GET", "codesearch.google.com", "/search/", 203, "codesearch.google.com/"},
 	{"GET", "codesearch.google.com", "/search/foo", 203, "codesearch.google.com/"},
 	{"GET", "codesearch.google.com", "/", 203, "codesearch.google.com/"},
+	{"GET", "codesearch.google.com:443", "/", 203, "codesearch.google.com/"},
 	{"GET", "images.google.com", "/search", 201, "/search"},
 	{"GET", "images.google.com", "/search/", 404, ""},
 	{"GET", "images.google.com", "/search/foo", 404, ""},

src/net/http/server.go

@@ -2167,6 +2167,19 @@ func cleanPath(p string) string {
 	return np
 }
 
+// stripHostPort returns h without any trailing ":<port>".
+func stripHostPort(h string) string {
+	// If no port on host, return unchanged
+	if strings.IndexByte(h, ':') == -1 {
+		return h
+	}
+	host, _, err := net.SplitHostPort(h)
+	if err != nil {
+		return h // on error, return unchanged
+	}
+	return host
+}
+
 // Find a handler on a handler map given a path string.
 // Most-specific (longest) pattern wins.
 func (mux *ServeMux) match(path string) (h Handler, pattern string) {
@@ -2195,7 +2208,10 @@ func (mux *ServeMux) match(path string) (h Handler, pattern string) {
 // consulting r.Method, r.Host, and r.URL.Path. It always returns
 // a non-nil handler. If the path is not in its canonical form, the
 // handler will be an internally-generated handler that redirects
-// to the canonical path.
+// to the canonical path. If the host contains a port, it is ignored
+// when matching handlers.
+//
+// The path and host are used unchanged for CONNECT requests.
 //
 // Handler also returns the registered pattern that matches the
 // request or, in the case of internally-generated redirects,
@@ -2204,16 +2220,24 @@ func (mux *ServeMux) match(path string) (h Handler, pattern string) {
 // If there is no registered handler that applies to the request,
 // Handler returns a ``page not found'' handler and an empty pattern.
 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)
-			url := *r.URL
-			url.Path = p
-			return RedirectHandler(url.String(), StatusMovedPermanently), pattern
-		}
+
+	// CONNECT requests are not canonicalized.
+	if r.Method == "CONNECT" {
+		return mux.handler(r.Host, r.URL.Path)
+	}
+
+	// All other requests have any port stripped and path cleaned
+	// before passing to mux.handler.
+	host := stripHostPort(r.Host)
+	path := cleanPath(r.URL.Path)
+	if path != r.URL.Path {
+		_, pattern = mux.handler(host, path)
+		url := *r.URL
+		url.Path = path
+		return RedirectHandler(url.String(), StatusMovedPermanently), pattern
 	}
 
-	return mux.handler(r.Host, r.URL.Path)
+	return mux.handler(host, r.URL.Path)
 }
 
 // handler is the main implementation of Handler.