net/http: update bundled http2

Updates bundled x/net/http2 to git rev 8dab9293 for:

    http2: make Transport retry on server's GOAWAY graceful shutdown
    https://golang.org/cl/33971

Fixes #18083

Change-Id: I676f5eb4b490a4d86356778bb17296c451f16d90
Reviewed-on: https://go-review.googlesource.com/34011
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tom Bergan <tombergan@google.com>

src/net/http/h2_bundle.go

@@ -2188,6 +2188,14 @@ func http2shouldLogPanic(panicValue interface{}) bool {
 	return panicValue != nil && panicValue != ErrAbortHandler
 }
 
+func http2reqGetBody(req *Request) func() (io.ReadCloser, error) {
+	return req.GetBody
+}
+
+func http2reqBodyIsNoBody(body io.ReadCloser) bool {
+	return body == NoBody
+}
+
 var http2DebugGoroutines = os.Getenv("DEBUG_HTTP2_GOROUTINES") == "1"
 
 type http2goroutineLock uint64
@@ -3247,6 +3255,11 @@ func (sc *http2serverConn) maxHeaderListSize() uint32 {
 	return uint32(n + typicalHeaders*perFieldOverhead)
 }
 
+func (sc *http2serverConn) curOpenStreams() uint32 {
+	sc.serveG.check()
+	return sc.curClientStreams + sc.curPushedStreams
+}
+
 // stream represents a stream. This is the minimal metadata needed by
 // the serve goroutine. Most of the actual stream state is owned by
 // the http.Handler's goroutine in the responseWriter. Because the
@@ -3560,7 +3573,7 @@ func (sc *http2serverConn) serve() {
 			fn(loopNum)
 		}
 
-		if sc.inGoAway && sc.curClientStreams == 0 && !sc.needToSendGoAway && !sc.writingFrame {
+		if sc.inGoAway && sc.curOpenStreams() == 0 && !sc.needToSendGoAway && !sc.writingFrame {
 			return
 		}
 	}
@@ -4373,7 +4386,7 @@ func (sc *http2serverConn) newStream(id, pusherID uint32, state http2streamState
 	} else {
 		sc.curClientStreams++
 	}
-	if sc.curClientStreams+sc.curPushedStreams == 1 {
+	if sc.curOpenStreams() == 1 {
 		sc.setConnState(StateActive)
 	}
 
@@ -5114,7 +5127,7 @@ func (w *http2responseWriter) push(target string, opts http2pushOptions) error {
 	}
 	for k := range opts.Header {
 		if strings.HasPrefix(k, ":") {
-			return fmt.Errorf("promised request headers cannot include psuedo header %q", k)
+			return fmt.Errorf("promised request headers cannot include pseudo header %q", k)
 		}
 
 		switch strings.ToLower(k) {
@@ -5510,6 +5523,7 @@ type http2clientStream struct {
 	ID            uint32
 	resc          chan http2resAndError
 	bufPipe       http2pipe // buffered pipe with the flow-controlled response payload
+	startedWrite  bool      // started request body write; guarded by cc.mu
 	requestedGzip bool
 	on100         func() // optional code to run if get a 100 continue response
 
@@ -5651,9 +5665,11 @@ func (t *http2Transport) RoundTripOpt(req *Request, opt http2RoundTripOpt) (*Res
 		}
 		http2traceGotConn(req, cc)
 		res, err := cc.RoundTrip(req)
-		if http2shouldRetryRequest(req, err) {
+		if err != nil {
+			if req, err = http2shouldRetryRequest(req, err); err == nil {
 				continue
 			}
+		}
 		if err != nil {
 			t.vlogf("RoundTrip failure: %v", err)
 			return nil, err
@@ -5674,11 +5690,39 @@ func (t *http2Transport) CloseIdleConnections() {
 var (
 	http2errClientConnClosed   = errors.New("http2: client conn is closed")
 	http2errClientConnUnusable = errors.New("http2: client conn not usable")
+
+	http2errClientConnGotGoAway                 = errors.New("http2: Transport received Server's graceful shutdown GOAWAY")
+	http2errClientConnGotGoAwayAfterSomeReqBody = errors.New("http2: Transport received Server's graceful shutdown GOAWAY; some request body already written")
 )
 
-func http2shouldRetryRequest(req *Request, err error) bool {
+// shouldRetryRequest is called by RoundTrip when a request fails to get
+// response headers. It is always called with a non-nil error.
+// It returns either a request to retry (either the same request, or a
+// modified clone), or an error if the request can't be replayed.
+func http2shouldRetryRequest(req *Request, err error) (*Request, error) {
+	switch err {
+	default:
+		return nil, err
+	case http2errClientConnUnusable, http2errClientConnGotGoAway:
+		return req, nil
+	case http2errClientConnGotGoAwayAfterSomeReqBody:
+
+		if req.Body == nil || http2reqBodyIsNoBody(req.Body) {
+			return req, nil
+		}
 
-	return err == http2errClientConnUnusable
+		getBody := http2reqGetBody(req)
+		if getBody == nil {
+			return nil, errors.New("http2: Transport: peer server initiated graceful shutdown after some of Request.Body was written; define Request.GetBody to avoid this error")
+		}
+		body, err := getBody()
+		if err != nil {
+			return nil, err
+		}
+		newReq := *req
+		newReq.Body = body
+		return &newReq, nil
+	}
 }
 
 func (t *http2Transport) dialClientConn(addr string, singleUse bool) (*http2ClientConn, error) {
@@ -5826,6 +5870,15 @@ func (cc *http2ClientConn) setGoAway(f *http2GoAwayFrame) {
 	if old != nil && old.ErrCode != http2ErrCodeNo {
 		cc.goAway.ErrCode = old.ErrCode
 	}
+	last := f.LastStreamID
+	for streamID, cs := range cc.streams {
+		if streamID > last {
+			select {
+			case cs.resc <- http2resAndError{err: http2errClientConnGotGoAway}:
+			default:
+			}
+		}
+	}
 }
 
 func (cc *http2ClientConn) CanTakeNewRequest() bool {
@@ -6059,6 +6112,13 @@ func (cc *http2ClientConn) RoundTrip(req *Request) (*Response, error) {
 			cs.abortRequestBodyWrite(http2errStopReqBodyWrite)
 		}
 		if re.err != nil {
+			if re.err == http2errClientConnGotGoAway {
+				cc.mu.Lock()
+				if cs.startedWrite {
+					re.err = http2errClientConnGotGoAwayAfterSomeReqBody
+				}
+				cc.mu.Unlock()
+			}
 			cc.forgetStreamID(cs.ID)
 			return nil, re.err
 		}
@@ -7225,6 +7285,9 @@ func (t *http2Transport) getBodyWriterState(cs *http2clientStream, body io.Reade
 	resc := make(chan error, 1)
 	s.resc = resc
 	s.fn = func() {
+		cs.cc.mu.Lock()
+		cs.startedWrite = true
+		cs.cc.mu.Unlock()
 		resc <- cs.writeRequestBody(body, cs.req.Body)
 	}
 	s.delay = t.expectContinueTimeout()
@@ -7644,7 +7707,9 @@ type http2WriteScheduler interface {
 	// https://tools.ietf.org/html/rfc7540#section-5.1
 	AdjustStream(streamID uint32, priority http2PriorityParam)
 
-	// Push queues a frame in the scheduler.
+	// Push queues a frame in the scheduler. In most cases, this will not be
+	// called with wr.StreamID()!=0 unless that stream is currently open. The one
+	// exception is RST_STREAM frames, which may be sent on idle or closed streams.
 	Push(wr http2FrameWriteRequest)
 
 	// Pop dequeues the next frame to write. Returns false if no frames can
@@ -8183,7 +8248,11 @@ func (ws *http2priorityWriteScheduler) Push(wr http2FrameWriteRequest) {
 	} else {
 		n = ws.nodes[id]
 		if n == nil {
-			panic("add on non-open stream")
+
+			if wr.DataSize() > 0 {
+				panic("add DATA on non-open stream")
+			}
+			n = &ws.root
 		}
 	}
 	n.q.push(wr)