Revert "net/http: close accepted connection"

This reverts CL 353714.

The change closes accepted connection also in graceful shutdown which
breaks the fix for #33313 (and apparent duplicate #36819).

The proper fix should close accepted connection only if server is closed
but not in graceful shutdown.

Updates #48642

Change-Id: I2f7005f3f3037e6563745731bb2693923b654004
GitHub-Last-Rev: f6d885aa37
GitHub-Pull-Request: golang/go#52823
Reviewed-on: https://go-review.googlesource.com/c/go/+/405454
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>

src/net/http/serve_test.go

@@ -6725,28 +6725,3 @@ func testMaxBytesHandler(t *testing.T, maxSize, requestSize int64) {
 		t.Errorf("expected echo of size %d; got %d", handlerN, buf.Len())
 	}
 }
-
-// Issue 48642: close accepted connection
-func TestServerCloseAccepted(t *testing.T) {
-	closed := 0
-	conn := &rwTestConn{
-		closeFunc: func() error {
-			closed++
-			return nil
-		},
-	}
-	ln := &oneConnListener{conn: conn}
-	var srv Server
-	// Use ConnContext to close server after connection is accepted but before it is tracked
-	srv.ConnContext = func(ctx context.Context, c net.Conn) context.Context {
-		srv.Close()
-		return ctx
-	}
-	got := srv.Serve(ln)
-	if got != ErrServerClosed {
-		t.Errorf("Serve err = %v; want ErrServerClosed", got)
-	}
-	if closed != 1 {
-		t.Errorf("Connection expected to be closed")
-	}
-}

src/net/http/server.go

@@ -1754,10 +1754,10 @@ const (
 func (c *conn) setState(nc net.Conn, state ConnState, runHook bool) {
 	srv := c.server
 	switch state {
+	case StateNew:
+		srv.trackConn(c, true)
 	case StateHijacked, StateClosed:
-		srv.mu.Lock()
-		delete(srv.activeConn, c)
-		srv.mu.Unlock()
+		srv.trackConn(c, false)
 	}
 	if state > 0xff || state < 0 {
 		panic("internal error")
@@ -3068,10 +3068,6 @@ func (srv *Server) Serve(l net.Listener) error {
 		}
 		tempDelay = 0
 		c := srv.newConn(rw)
-		if !srv.trackConn(c) {
-			rw.Close()
-			return ErrServerClosed
-		}
 		c.setState(c.rwc, StateNew, runHooks) // before Serve can return
 		go c.serve(connCtx)
 	}
@@ -3143,19 +3139,17 @@ func (s *Server) trackListener(ln *net.Listener, add bool) bool {
 	return true
 }
 
-// trackConn adds a connection to the set of tracked connections.
-// It reports whether the server is still up (not Shutdown or Closed).
-func (s *Server) trackConn(c *conn) bool {
+func (s *Server) trackConn(c *conn, add bool) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
-	if s.shuttingDown() {
-		return false
-	}
 	if s.activeConn == nil {
 		s.activeConn = make(map[*conn]struct{})
 	}
-	s.activeConn[c] = struct{}{}
-	return true
+	if add {
+		s.activeConn[c] = struct{}{}
+	} else {
+		delete(s.activeConn, c)
+	}
 }
 
 func (s *Server) idleTimeout() time.Duration {