Differences between x/net/http2/transport.go tip@66aacef3dd8a676686c7ae3716979581e8b03c47 vs working version@5961165da77ad3a2abf3a77ea904c13a76b0b073 which are 66 commits apart

diff.diff

--- tr_5961165da77ad3a2abf3a77ea904c13a76b0b073.go	2017-09-19 02:59:26.000000000 -0600
+++ tr_master.go	2017-09-19 03:01:42.000000000 -0600
@@ -18,6 +18,7 @@
 	"io/ioutil"
 	"log"
 	"math"
+	mathrand "math/rand"
 	"net"
 	"net/http"
 	"sort"
@@ -86,7 +87,7 @@
 
 	// MaxHeaderListSize is the http2 SETTINGS_MAX_HEADER_LIST_SIZE to
 	// send in the initial settings frame. It is how many bytes
-	// of response headers are allow. Unlike the http2 spec, zero here
+	// of response headers are allowed. Unlike the http2 spec, zero here
 	// means to use a default limit (currently 10MB). If you actually
 	// want to advertise an ulimited value to the peer, Transport
 	// interprets the highest possible value here (0xffffffff or 1<<32-1)
@@ -164,15 +165,17 @@
 	goAwayDebug     string                   // goAway frame's debug data, retained as a string
 	streams         map[uint32]*clientStream // client-initiated
 	nextStreamID    uint32
+	pendingRequests int                       // requests blocked and waiting to be sent because len(streams) == maxConcurrentStreams
 	pings           map[[8]byte]chan struct{} // in flight ping data to notification channel
 	bw              *bufio.Writer
 	br              *bufio.Reader
 	fr              *Framer
 	lastActive      time.Time
 	// Settings from peer: (also guarded by mu)
-	maxFrameSize         uint32
-	maxConcurrentStreams uint32
-	initialWindowSize    uint32
+	maxFrameSize          uint32
+	maxConcurrentStreams  uint32
+	peerMaxHeaderListSize uint64
+	initialWindowSize     uint32
 
 	hbuf    bytes.Buffer // HPACK encoder writes into this
 	henc    *hpack.Encoder
@@ -216,35 +219,45 @@
 	resTrailer *http.Header // client's Response.Trailer
 }
 
-// awaitRequestCancel runs in its own goroutine and waits for the user
-// to cancel a RoundTrip request, its context to expire, or for the
-// request to be done (any way it might be removed from the cc.streams
-// map: peer reset, successful completion, TCP connection breakage,
-// etc)
-func (cs *clientStream) awaitRequestCancel(req *http.Request) {
+// awaitRequestCancel waits for the user to cancel a request or for the done
+// channel to be signaled. A non-nil error is returned only if the request was
+// canceled.
+func awaitRequestCancel(req *http.Request, done <-chan struct{}) error {
 	ctx := reqContext(req)
 	if req.Cancel == nil && ctx.Done() == nil {
-		return
+		return nil
 	}
 	select {
 	case <-req.Cancel:
-		cs.cancelStream()
-		cs.bufPipe.CloseWithError(errRequestCanceled)
+		return errRequestCanceled
 	case <-ctx.Done():
+		return ctx.Err()
+	case <-done:
+		return nil
+	}
+}
+
+// awaitRequestCancel waits for the user to cancel a request, its context to
+// expire, or for the request to be done (any way it might be removed from the
+// cc.streams map: peer reset, successful completion, TCP connection breakage,
+// etc). If the request is canceled, then cs will be canceled and closed.
+func (cs *clientStream) awaitRequestCancel(req *http.Request) {
+	if err := awaitRequestCancel(req, cs.done); err != nil {
 		cs.cancelStream()
-		cs.bufPipe.CloseWithError(ctx.Err())
-	case <-cs.done:
+		cs.bufPipe.CloseWithError(err)
 	}
 }
 
 func (cs *clientStream) cancelStream() {
-	cs.cc.mu.Lock()
+	cc := cs.cc
+	cc.mu.Lock()
 	didReset := cs.didReset
 	cs.didReset = true
-	cs.cc.mu.Unlock()
+	cc.mu.Unlock()
 
 	if !didReset {
-		cs.cc.writeStreamReset(cs.ID, ErrCodeCancel, nil)
+		cc.writeStreamReset(cs.ID, ErrCodeCancel, nil)
+		cc.forgetStreamID(cs.ID)
 	}
 }
 
@@ -329,7 +342,7 @@
 	}
 
 	addr := authorityAddr(req.URL.Scheme, req.URL.Host)
-	for {
+	for retry := 0; ; retry++ {
 		cc, err := t.connPool().GetClientConn(req, addr)
 		if err != nil {
 			t.vlogf("http2: Transport failed to get client conn for %s: %v", addr, err)
@@ -337,9 +350,25 @@
 		}
 		traceGotConn(req, cc)
 		res, err := cc.RoundTrip(req)
-		if err != nil {
-			if req, err = shouldRetryRequest(req, err); err == nil {
-				continue
+		if err != nil && retry <= 6 {
+			afterBodyWrite := false
+			if e, ok := err.(afterReqBodyWriteError); ok {
+				err = e
+				afterBodyWrite = true
+			}
+			if req, err = shouldRetryRequest(req, err, afterBodyWrite); err == nil {
+				// After the first retry, do exponential backoff with 10% jitter.
+				if retry == 0 {
+					continue
+				}
+				backoff := float64(uint(1) << (uint(retry) - 1))
+				backoff += backoff * (0.1 * mathrand.Float64())
+				select {
+				case <-time.After(time.Second * time.Duration(backoff)):
+					continue
+				case <-reqContext(req).Done():
+					return nil, reqContext(req).Err()
+				}
 			}
 		}
 		if err != nil {
@@ -360,43 +389,60 @@
 }
 
 var (
-	errClientConnClosed   = errors.New("http2: client conn is closed")
-	errClientConnUnusable = errors.New("http2: client conn not usable")
-
-	errClientConnGotGoAway                 = errors.New("http2: Transport received Server's graceful shutdown GOAWAY")
-	errClientConnGotGoAwayAfterSomeReqBody = errors.New("http2: Transport received Server's graceful shutdown GOAWAY; some request body already written")
+	errClientConnClosed    = errors.New("http2: client conn is closed")
+	errClientConnUnusable  = errors.New("http2: client conn not usable")
+	errClientConnGotGoAway = errors.New("http2: Transport received Server's graceful shutdown GOAWAY")
 )
 
+// afterReqBodyWriteError is a wrapper around errors returned by ClientConn.RoundTrip.
+// It is used to signal that err happened after part of Request.Body was sent to the server.
+type afterReqBodyWriteError struct {
+	err error
+}
+
+func (e afterReqBodyWriteError) Error() string {
+	return e.err.Error() + "; some request body already written"
+}
+
 // 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 shouldRetryRequest(req *http.Request, err error) (*http.Request, error) {
-	switch err {
-	default:
+func shouldRetryRequest(req *http.Request, err error, afterBodyWrite bool) (*http.Request, error) {
+	if !canRetryError(err) {
 		return nil, err
-	case errClientConnUnusable, errClientConnGotGoAway:
+	}
+	if !afterBodyWrite {
 		return req, nil
-	case errClientConnGotGoAwayAfterSomeReqBody:
-		// If the Body is nil (or http.NoBody), it's safe to reuse
-		// this request and its Body.
-		if req.Body == nil || reqBodyIsNoBody(req.Body) {
-			return req, nil
-		}
-		// Otherwise we depend on the Request having its GetBody
-		// func defined.
-		getBody := reqGetBody(req) // Go 1.8: getBody = req.GetBody
-		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
 	}
+	// If the Body is nil (or http.NoBody), it's safe to reuse
+	// this request and its Body.
+	if req.Body == nil || reqBodyIsNoBody(req.Body) {
+		return req, nil
+	}
+	// Otherwise we depend on the Request having its GetBody
+	// func defined.
+	getBody := reqGetBody(req) // Go 1.8: getBody = req.GetBody
+	if getBody == nil {
+		return nil, fmt.Errorf("http2: Transport: cannot retry err [%v] after Request.Body was written; define Request.GetBody to avoid this error", err)
+	}
+	body, err := getBody()
+	if err != nil {
+		return nil, err
+	}
+	newReq := *req
+	newReq.Body = body
+	return &newReq, nil
+}
+
+func canRetryError(err error) bool {
+	if err == errClientConnUnusable || err == errClientConnGotGoAway {
+		return true
+	}
+	if se, ok := err.(StreamError); ok {
+		return se.Code == ErrCodeRefusedStream
+	}
+	return false
 }
 
 func (t *Transport) dialClientConn(addr string, singleUse bool) (*ClientConn, error) {
@@ -474,17 +520,18 @@
 
 func (t *Transport) newClientConn(c net.Conn, singleUse bool) (*ClientConn, error) {
 	cc := &ClientConn{
-		t:                    t,
-		tconn:                c,
-		readerDone:           make(chan struct{}),
-		nextStreamID:         1,
-		maxFrameSize:         16 << 10, // spec default
-		initialWindowSize:    65535,    // spec default
-		maxConcurrentStreams: 1000,     // "infinite", per spec. 1000 seems good enough.
-		streams:              make(map[uint32]*clientStream),
-		singleUse:            singleUse,
-		wantSettingsAck:      true,
-		pings:                make(map[[8]byte]chan struct{}),
+		t:                     t,
+		tconn:                 c,
+		readerDone:            make(chan struct{}),
+		nextStreamID:          1,
+		maxFrameSize:          16 << 10,           // spec default
+		initialWindowSize:     65535,              // spec default
+		maxConcurrentStreams:  1000,               // "infinite", per spec. 1000 seems good enough.
+		peerMaxHeaderListSize: 0xffffffffffffffff, // "infinite", per spec. Use 2^64-1 instead.
+		streams:               make(map[uint32]*clientStream),
+		singleUse:             singleUse,
+		wantSettingsAck:       true,
+		pings:                 make(map[[8]byte]chan struct{}),
 	}
 	if d := t.idleConnTimeout(); d != 0 {
 		cc.idleTimeout = d
@@ -560,6 +607,8 @@
 	}
 }
 
+// CanTakeNewRequest reports whether the connection can take a new request,
+// meaning it has not been closed or received or sent a GOAWAY.
 func (cc *ClientConn) CanTakeNewRequest() bool {
 	cc.mu.Lock()
 	defer cc.mu.Unlock()
@@ -571,8 +620,7 @@
 		return false
 	}
 	return cc.goAway == nil && !cc.closed &&
-		int64(len(cc.streams)+1) < int64(cc.maxConcurrentStreams) &&
-		cc.nextStreamID < math.MaxInt32
+		int64(cc.nextStreamID)+int64(cc.pendingRequests) < math.MaxInt32
 }
 
 // onIdleTimeout is called from a time.AfterFunc goroutine. It will
@@ -694,7 +742,7 @@
 // req.ContentLength, where 0 actually means zero (not unknown) and -1
 // means unknown.
 func actualContentLength(req *http.Request) int64 {
-	if req.Body == nil {
+	if req.Body == nil || reqBodyIsNoBody(req.Body) {
 		return 0
 	}
 	if req.ContentLength != 0 {
@@ -718,15 +766,14 @@
 	hasTrailers := trailers != ""
 
 	cc.mu.Lock()
-	cc.lastActive = time.Now()
-	if cc.closed || !cc.canTakeNewRequestLocked() {
+	if err := cc.awaitOpenSlotForRequest(req); err != nil {
 		cc.mu.Unlock()
-		return nil, errClientConnUnusable
+		return nil, err
 	}
 
 	body := req.Body
-	hasBody := body != nil
 	contentLen := actualContentLength(req)
+	hasBody := contentLen != 0
 
 	// TODO(bradfitz): this is a copy of the logic in net/http. Unify somewhere?
 	var requestedGzip bool
@@ -816,14 +863,13 @@
 			cs.abortRequestBodyWrite(errStopReqBodyWrite)
 		}
 		if re.err != nil {
-			if re.err == errClientConnGotGoAway {
-				cc.mu.Lock()
-				if cs.startedWrite {
-					re.err = errClientConnGotGoAwayAfterSomeReqBody
-				}
-				cc.mu.Unlock()
-			}
+			cc.mu.Lock()
+			afterBodyWrite := cs.startedWrite
+			cc.mu.Unlock()
 			cc.forgetStreamID(cs.ID)
+			if afterBodyWrite {
+				return nil, afterReqBodyWriteError{re.err}
+			}
 			return nil, re.err
 		}
 		res.Request = req
@@ -836,31 +882,31 @@
 		case re := <-readLoopResCh:
 			return handleReadLoopResponse(re)
 		case <-respHeaderTimer:
-			cc.forgetStreamID(cs.ID)
 			if !hasBody || bodyWritten {
 				cc.writeStreamReset(cs.ID, ErrCodeCancel, nil)
 			} else {
 				bodyWriter.cancel()
 				cs.abortRequestBodyWrite(errStopReqBodyWriteAndCancel)
 			}
+			cc.forgetStreamID(cs.ID)
 			return nil, errTimeout
 		case <-ctx.Done():
-			cc.forgetStreamID(cs.ID)
 			if !hasBody || bodyWritten {
 				cc.writeStreamReset(cs.ID, ErrCodeCancel, nil)
 			} else {
 				bodyWriter.cancel()
 				cs.abortRequestBodyWrite(errStopReqBodyWriteAndCancel)
 			}
+			cc.forgetStreamID(cs.ID)
 			return nil, ctx.Err()
 		case <-req.Cancel:
-			cc.forgetStreamID(cs.ID)
 			if !hasBody || bodyWritten {
 				cc.writeStreamReset(cs.ID, ErrCodeCancel, nil)
 			} else {
 				bodyWriter.cancel()
 				cs.abortRequestBodyWrite(errStopReqBodyWriteAndCancel)
 			}
+			cc.forgetStreamID(cs.ID)
 			return nil, errRequestCanceled
 		case <-cs.peerReset:
 			// processResetStream already removed the
@@ -887,6 +933,45 @@
 	}
 }
 
+// awaitOpenSlotForRequest waits until len(streams) < maxConcurrentStreams.
+// Must hold cc.mu.
+func (cc *ClientConn) awaitOpenSlotForRequest(req *http.Request) error {
+	var waitingForConn chan struct{}
+	var waitingForConnErr error // guarded by cc.mu
+	for {
+		cc.lastActive = time.Now()
+		if cc.closed || !cc.canTakeNewRequestLocked() {
+			return errClientConnUnusable
+		}
+		if int64(len(cc.streams))+1 <= int64(cc.maxConcurrentStreams) {
+			if waitingForConn != nil {
+				close(waitingForConn)
+			}
+			return nil
+		}
+		// Unfortunately, we cannot wait on a condition variable and channel at
+		// the same time, so instead, we spin up a goroutine to check if the
+		// request is canceled while we wait for a slot to open in the connection.
+		if waitingForConn == nil {
+			waitingForConn = make(chan struct{})
+			go func() {
+				if err := awaitRequestCancel(req, waitingForConn); err != nil {
+					cc.mu.Lock()
+					waitingForConnErr = err
+					cc.cond.Broadcast()
+					cc.mu.Unlock()
+				}
+			}()
+		}
+		cc.pendingRequests++
+		cc.cond.Wait()
+		cc.pendingRequests--
+		if waitingForConnErr != nil {
+			return waitingForConnErr
+		}
+	}
+}
+
 // requires cc.wmu be held
 func (cc *ClientConn) writeHeaders(streamID uint32, endStream bool, hdrs []byte) error {
 	first := true // first frame written (HEADERS is first, then CONTINUATION)
@@ -1002,8 +1087,13 @@
 	var trls []byte
 	if hasTrailers {
 		cc.mu.Lock()
-		defer cc.mu.Unlock()
-		trls = cc.encodeTrailers(req)
+		trls, err = cc.encodeTrailers(req)
+		cc.mu.Unlock()
+		if err != nil {
+			cc.writeStreamReset(cs.ID, ErrCodeInternal, err)
+			cc.forgetStreamID(cs.ID)
+			return err
+		}
 	}
 
 	cc.wmu.Lock()
@@ -1106,62 +1196,86 @@
 		}
 	}
 
-	// 8.1.2.3 Request Pseudo-Header Fields
-	// The :path pseudo-header field includes the path and query parts of the
-	// target URI (the path-absolute production and optionally a '?' character
-	// followed by the query production (see Sections 3.3 and 3.4 of
-	// [RFC3986]).
-	cc.writeHeader(":authority", host)
-	cc.writeHeader(":method", req.Method)
-	if req.Method != "CONNECT" {
-		cc.writeHeader(":path", path)
-		cc.writeHeader(":scheme", req.URL.Scheme)
-	}
-	if trailers != "" {
-		cc.writeHeader("trailer", trailers)
-	}
-
-	var didUA bool
-	for k, vv := range req.Header {
-		lowKey := strings.ToLower(k)
-		switch lowKey {
-		case "host", "content-length":
-			// Host is :authority, already sent.
-			// Content-Length is automatic, set below.
-			continue
-		case "connection", "proxy-connection", "transfer-encoding", "upgrade", "keep-alive":
-			// Per 8.1.2.2 Connection-Specific Header
-			// Fields, don't send connection-specific
-			// fields. We have already checked if any
-			// are error-worthy so just ignore the rest.
-			continue
-		case "user-agent":
-			// Match Go's http1 behavior: at most one
-			// User-Agent. If set to nil or empty string,
-			// then omit it. Otherwise if not mentioned,
-			// include the default (below).
-			didUA = true
-			if len(vv) < 1 {
+	enumerateHeaders := func(f func(name, value string)) {
+		// 8.1.2.3 Request Pseudo-Header Fields
+		// The :path pseudo-header field includes the path and query parts of the
+		// target URI (the path-absolute production and optionally a '?' character
+		// followed by the query production (see Sections 3.3 and 3.4 of
+		// [RFC3986]).
+		f(":authority", host)
+		f(":method", req.Method)
+		if req.Method != "CONNECT" {
+			f(":path", path)
+			f(":scheme", req.URL.Scheme)
+		}
+		if trailers != "" {
+			f("trailer", trailers)
+		}
+
+		var didUA bool
+		for k, vv := range req.Header {
+			if strings.EqualFold(k, "host") || strings.EqualFold(k, "content-length") {
+				// Host is :authority, already sent.
+				// Content-Length is automatic, set below.
 				continue
-			}
-			vv = vv[:1]
-			if vv[0] == "" {
+			} else if strings.EqualFold(k, "connection") || strings.EqualFold(k, "proxy-connection") ||
+				strings.EqualFold(k, "transfer-encoding") || strings.EqualFold(k, "upgrade") ||
+				strings.EqualFold(k, "keep-alive") {
+				// Per 8.1.2.2 Connection-Specific Header
+				// Fields, don't send connection-specific
+				// fields. We have already checked if any
+				// are error-worthy so just ignore the rest.
 				continue
+			} else if strings.EqualFold(k, "user-agent") {
+				// Match Go's http1 behavior: at most one
+				// User-Agent. If set to nil or empty string,
+				// then omit it. Otherwise if not mentioned,
+				// include the default (below).
+				didUA = true
+				if len(vv) < 1 {
+					continue
+				}
+				vv = vv[:1]
+				if vv[0] == "" {
+					continue
+				}
+
+			}
+
+			for _, v := range vv {
+				f(k, v)
 			}
 		}
-		for _, v := range vv {
-			cc.writeHeader(lowKey, v)
+		if shouldSendReqContentLength(req.Method, contentLength) {
+			f("content-length", strconv.FormatInt(contentLength, 10))
+		}
+		if addGzipHeader {
+			f("accept-encoding", "gzip")
+		}
+		if !didUA {
+			f("user-agent", defaultUserAgent)
 		}
 	}
-	if shouldSendReqContentLength(req.Method, contentLength) {
-		cc.writeHeader("content-length", strconv.FormatInt(contentLength, 10))
-	}
-	if addGzipHeader {
-		cc.writeHeader("accept-encoding", "gzip")
-	}
-	if !didUA {
-		cc.writeHeader("user-agent", defaultUserAgent)
+
+	// Do a first pass over the headers counting bytes to ensure
+	// we don't exceed cc.peerMaxHeaderListSize. This is done as a
+	// separate pass before encoding the headers to prevent
+	// modifying the hpack state.
+	hlSize := uint64(0)
+	enumerateHeaders(func(name, value string) {
+		hf := hpack.HeaderField{Name: name, Value: value}
+		hlSize += uint64(hf.Size())
+	})
+
+	if hlSize > cc.peerMaxHeaderListSize {
+		return nil, errRequestHeaderListSize
 	}
+
+	// Header list size is ok. Write the headers.
+	enumerateHeaders(func(name, value string) {
+		cc.writeHeader(strings.ToLower(name), value)
+	})
+
 	return cc.hbuf.Bytes(), nil
 }
 
@@ -1188,17 +1302,29 @@
 }
 
 // requires cc.mu be held.
-func (cc *ClientConn) encodeTrailers(req *http.Request) []byte {
+func (cc *ClientConn) encodeTrailers(req *http.Request) ([]byte, error) {
 	cc.hbuf.Reset()
+
+	hlSize := uint64(0)
+	for k, vv := range req.Trailer {
+		for _, v := range vv {
+			hf := hpack.HeaderField{Name: k, Value: v}
+			hlSize += uint64(hf.Size())
+		}
+	}
+	if hlSize > cc.peerMaxHeaderListSize {
+		return nil, errRequestHeaderListSize
+	}
+
 	for k, vv := range req.Trailer {
-		// Transfer-Encoding, etc.. have already been filter at the
+		// Transfer-Encoding, etc.. have already been filtered at the
 		// start of RoundTrip
 		lowKey := strings.ToLower(k)
 		for _, v := range vv {
 			cc.writeHeader(lowKey, v)
 		}
 	}
-	return cc.hbuf.Bytes()
+	return cc.hbuf.Bytes(), nil
 }
 
 func (cc *ClientConn) writeHeader(name, value string) {
@@ -1246,7 +1372,9 @@
 			cc.idleTimer.Reset(cc.idleTimeout)
 		}
 		close(cs.done)
-		cc.cond.Broadcast() // wake up checkResetOrDone via clientStream.awaitFlowControl
+		// Wake up checkResetOrDone via clientStream.awaitFlowControl and
+		// wake up RoundTrip if there is a pending request.
+		cc.cond.Broadcast()
 	}
 	return cs
 }
@@ -1345,8 +1473,9 @@
 			cc.vlogf("http2: Transport readFrame error on conn %p: (%T) %v", cc, err, err)
 		}
 		if se, ok := err.(StreamError); ok {
-			if cs := cc.streamByID(se.StreamID, true /*ended; remove it*/); cs != nil {
+			if cs := cc.streamByID(se.StreamID, false); cs != nil {
 				cs.cc.writeStreamReset(cs.ID, se.Code, err)
+				cs.cc.forgetStreamID(cs.ID)
 				if se.Cause == nil {
 					se.Cause = cc.fr.errDetail
 				}
@@ -1655,6 +1784,7 @@
 		cc.wmu.Lock()
 		if !serverSentStreamEnd {
 			cc.fr.WriteRSTStream(cs.ID, ErrCodeCancel)
+			cs.didReset = true
 		}
 		// Return connection-level flow control.
 		if unread > 0 {
@@ -1667,6 +1797,7 @@
 	}
 
 	cs.bufPipe.BreakWithError(errClosedResponseBody)
+	cc.forgetStreamID(cs.ID)
 	return nil
 }
 
@@ -1701,13 +1832,15 @@
 		}
 		return nil
 	}
+	if !cs.firstByte {
+		cc.logf("protocol error: received DATA before a HEADERS frame")
+		rl.endStreamError(cs, StreamError{
+			StreamID: f.StreamID,
+			Code:     ErrCodeProtocol,
+		})
+		return nil
+	}
 	if f.Length > 0 {
-		if len(data) > 0 && cs.bufPipe.b == nil {
-			// Data frame after it's already closed?
-			cc.logf("http2: Transport received DATA frame for closed stream; closing connection")
-			return ConnectionError(ErrCodeProtocol)
-		}
-
 		// Check connection-level flow control.
 		cc.mu.Lock()
 		if cs.inflow.available() >= int32(f.Length) {
@@ -1718,16 +1851,27 @@
 		}
 		// Return any padded flow control now, since we won't
 		// refund it later on body reads.
-		if pad := int32(f.Length) - int32(len(data)); pad > 0 {
-			cs.inflow.add(pad)
-			cc.inflow.add(pad)
+		var refund int
+		if pad := int(f.Length) - len(data); pad > 0 {
+			refund += pad
+		}
+		// Return len(data) now if the stream is already closed,
+		// since data will never be read.
+		didReset := cs.didReset
+		if didReset {
+			refund += len(data)
+		}
+		if refund > 0 {
+			cc.inflow.add(int32(refund))
 			cc.wmu.Lock()
-			cc.fr.WriteWindowUpdate(0, uint32(pad))
-			cc.fr.WriteWindowUpdate(cs.ID, uint32(pad))
+			cc.fr.WriteWindowUpdate(0, uint32(refund))
+			if !didReset {
+				cs.inflow.add(int32(refund))
+				cc.fr.WriteWindowUpdate(cs.ID, uint32(refund))
+			}
 			cc.bw.Flush()
 			cc.wmu.Unlock()
 		}
-		didReset := cs.didReset
 		cc.mu.Unlock()
 
 		if len(data) > 0 && !didReset {
@@ -1810,6 +1954,8 @@
 			cc.maxFrameSize = s.Val
 		case SettingMaxConcurrentStreams:
 			cc.maxConcurrentStreams = s.Val
+		case SettingMaxHeaderListSize:
+			cc.peerMaxHeaderListSize = uint64(s.Val)
 		case SettingInitialWindowSize:
 			// Values above the maximum flow-control
 			// window size of 2^31-1 MUST be treated as a
@@ -1976,6 +2122,7 @@
 
 var (
 	errResponseHeaderListSize = errors.New("http2: response header list larger than advertised limit")
+	errRequestHeaderListSize  = errors.New("http2: request header list larger than peer's advertised limit")
 	errPseudoTrailers         = errors.New("http2: invalid pseudo header in trailers")
 )
 
@@ -2125,4 +2272,4 @@
 // connection for a single request and then close the connection.
 func isConnectionCloseRequest(req *http.Request) bool {
 	return req.Close || httplex.HeaderValuesContainsToken(req.Header["Connection"], "close")
-}
+}
\ No newline at end of file