net/http: fix response Connection: close, close client connections

Fixes #3663
Updates #3540 (fixes it more)
Updates #1967 (fixes it more, re-enables a test)

R=golang-dev, n13m3y3r
CC=golang-dev
https://golang.org/cl/6213064

src/pkg/net/http/serve_test.go

@@ -386,17 +386,18 @@ func testTCPConnectionCloses(t *testing.T, req string, h Handler) {
 	}
 
 	r := bufio.NewReader(conn)
-	_, err = ReadResponse(r, &Request{Method: "GET"})
+	res, err := ReadResponse(r, &Request{Method: "GET"})
 	if err != nil {
 		t.Fatal("ReadResponse error:", err)
 	}
 
-	success := make(chan bool)
+	didReadAll := make(chan bool, 1)
 	go func() {
 		select {
 		case <-time.After(5 * time.Second):
-			t.Fatal("body not closed after 5s")
+			t.Error("body not closed after 5s")
-		case <-success:
+			return
+		case <-didReadAll:
 		}
 	}()
 
@@ -404,8 +405,11 @@ func testTCPConnectionCloses(t *testing.T, req string, h Handler) {
 	if err != nil {
 		t.Fatal("read error:", err)
 	}
+	didReadAll <- true
 
-	success <- true
+	if !res.Close {
+		t.Errorf("Response.Close = false; want true")
+	}
 }
 
 // TestServeHTTP10Close verifies that HTTP/1.0 requests won't be kept alive.

src/pkg/net/http/server.go

@@ -389,6 +389,11 @@ func (w *response) WriteHeader(code int) {
 	if !w.req.ProtoAtLeast(1, 0) {
 		return
 	}
+
+	if w.closeAfterReply && !hasToken(w.header.Get("Connection"), "close") {
+		w.header.Set("Connection", "close")
+	}
+
 	proto := "HTTP/1.0"
 	if w.req.ProtoAtLeast(1, 1) {
 		proto = "HTTP/1.1"

src/pkg/net/http/transport.go

@@ -480,6 +480,7 @@ type persistConn struct {
 	t        *Transport
 	cacheKey string // its connectMethod.String()
 	conn     net.Conn
+	closed   bool                // whether conn has been closed
 	br       *bufio.Reader       // from conn
 	bw       *bufio.Writer       // to conn
 	reqch    chan requestAndChan // written by roundTrip(); read by readLoop()
@@ -574,6 +575,9 @@ func (pc *persistConn) readLoop() {
 				if alive && !pc.t.putIdleConn(pc) {
 					alive = false
 				}
+				if !alive {
+					pc.close()
+				}
 				waitForBodyRead <- true
 			}
 		}
@@ -669,7 +673,10 @@ func (pc *persistConn) close() {
 
 func (pc *persistConn) closeLocked() {
 	pc.broken = true
-	pc.conn.Close()
+	if !pc.closed {
+		pc.conn.Close()
+		pc.closed = true
+	}
 	pc.mutateHeaderFunc = nil
 }
 

src/pkg/net/http/transport_test.go

@@ -37,17 +37,21 @@ var hostPortHandler = HandlerFunc(func(w ResponseWriter, r *Request) {
 	w.Write([]byte(r.RemoteAddr))
 })
 
+// testCloseConn is a net.Conn tracked by a testConnSet.
 type testCloseConn struct {
 	net.Conn
 	set *testConnSet
 }
 
-func (conn *testCloseConn) Close() error {
+func (c *testCloseConn) Close() error {
-	conn.set.remove(conn)
+	c.set.remove(c)
-	return conn.Conn.Close()
+	return c.Conn.Close()
 }
 
+// testConnSet tracks a set of TCP connections and whether they've
+// been closed.
 type testConnSet struct {
+	t      *testing.T
 	closed map[net.Conn]bool
 	list   []net.Conn // in order created
 	mutex  sync.Mutex
@@ -67,8 +71,9 @@ func (tcs *testConnSet) remove(c net.Conn) {
 }
 
 // some tests use this to manage raw tcp connections for later inspection
-func makeTestDial() (*testConnSet, func(n, addr string) (net.Conn, error)) {
+func makeTestDial(t *testing.T) (*testConnSet, func(n, addr string) (net.Conn, error)) {
 	connSet := &testConnSet{
+		t:      t,
 		closed: make(map[net.Conn]bool),
 	}
 	dial := func(n, addr string) (net.Conn, error) {
@@ -89,10 +94,7 @@ func (tcs *testConnSet) check(t *testing.T) {
 
 	for i, c := range tcs.list {
 		if !tcs.closed[c] {
-			// TODO(bradfitz,gustavo): make the following
+			t.Errorf("TCP connection #%d, %p (of %d total) was not closed", i+1, c, len(tcs.list))
-			// line an Errorf, not Logf, once issue 3540
-			// is fixed again.
-			t.Logf("TCP connection #%d (of %d total) was not closed", i+1, len(tcs.list))
 		}
 	}
 }
@@ -134,7 +136,7 @@ func TestTransportConnectionCloseOnResponse(t *testing.T) {
 	ts := httptest.NewServer(hostPortHandler)
 	defer ts.Close()
 
-	connSet, testDial := makeTestDial()
+	connSet, testDial := makeTestDial(t)
 
 	for _, connectionClose := range []bool{false, true} {
 		tr := &Transport{
@@ -184,7 +186,7 @@ func TestTransportConnectionCloseOnRequest(t *testing.T) {
 	ts := httptest.NewServer(hostPortHandler)
 	defer ts.Close()
 
-	connSet, testDial := makeTestDial()
+	connSet, testDial := makeTestDial(t)
 
 	for _, connectionClose := range []bool{false, true} {
 		tr := &Transport{