[VOL-4289]  Proto changes for gRPC migration

Change-Id: I317a0a865ccf78d0c37aa229c50d293a3f66c8bb
diff --git a/vendor/google.golang.org/grpc/internal/transport/http2_server.go b/vendor/google.golang.org/grpc/internal/transport/http2_server.go
new file mode 100644
index 0000000..19c13e0
--- /dev/null
+++ b/vendor/google.golang.org/grpc/internal/transport/http2_server.go
@@ -0,0 +1,1379 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package transport
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"math"
+	"net"
+	"net/http"
+	"strconv"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/golang/protobuf/proto"
+	"golang.org/x/net/http2"
+	"golang.org/x/net/http2/hpack"
+	"google.golang.org/grpc/internal/grpcutil"
+
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/internal/channelz"
+	"google.golang.org/grpc/internal/grpcrand"
+	"google.golang.org/grpc/keepalive"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/peer"
+	"google.golang.org/grpc/stats"
+	"google.golang.org/grpc/status"
+	"google.golang.org/grpc/tap"
+)
+
+var (
+	// ErrIllegalHeaderWrite indicates that setting header is illegal because of
+	// the stream's state.
+	ErrIllegalHeaderWrite = errors.New("transport: the stream is done or WriteHeader was already called")
+	// ErrHeaderListSizeLimitViolation indicates that the header list size is larger
+	// than the limit set by peer.
+	ErrHeaderListSizeLimitViolation = errors.New("transport: trying to send header list size larger than the limit set by peer")
+)
+
+// serverConnectionCounter counts the number of connections a server has seen
+// (equal to the number of http2Servers created). Must be accessed atomically.
+var serverConnectionCounter uint64
+
+// http2Server implements the ServerTransport interface with HTTP2.
+type http2Server struct {
+	lastRead    int64 // Keep this field 64-bit aligned. Accessed atomically.
+	ctx         context.Context
+	done        chan struct{}
+	conn        net.Conn
+	loopy       *loopyWriter
+	readerDone  chan struct{} // sync point to enable testing.
+	writerDone  chan struct{} // sync point to enable testing.
+	remoteAddr  net.Addr
+	localAddr   net.Addr
+	maxStreamID uint32               // max stream ID ever seen
+	authInfo    credentials.AuthInfo // auth info about the connection
+	inTapHandle tap.ServerInHandle
+	framer      *framer
+	// The max number of concurrent streams.
+	maxStreams uint32
+	// controlBuf delivers all the control related tasks (e.g., window
+	// updates, reset streams, and various settings) to the controller.
+	controlBuf *controlBuffer
+	fc         *trInFlow
+	stats      stats.Handler
+	// Keepalive and max-age parameters for the server.
+	kp keepalive.ServerParameters
+	// Keepalive enforcement policy.
+	kep keepalive.EnforcementPolicy
+	// The time instance last ping was received.
+	lastPingAt time.Time
+	// Number of times the client has violated keepalive ping policy so far.
+	pingStrikes uint8
+	// Flag to signify that number of ping strikes should be reset to 0.
+	// This is set whenever data or header frames are sent.
+	// 1 means yes.
+	resetPingStrikes      uint32 // Accessed atomically.
+	initialWindowSize     int32
+	bdpEst                *bdpEstimator
+	maxSendHeaderListSize *uint32
+
+	mu sync.Mutex // guard the following
+
+	// drainChan is initialized when Drain() is called the first time.
+	// After which the server writes out the first GoAway(with ID 2^31-1) frame.
+	// Then an independent goroutine will be launched to later send the second GoAway.
+	// During this time we don't want to write another first GoAway(with ID 2^31 -1) frame.
+	// Thus call to Drain() will be a no-op if drainChan is already initialized since draining is
+	// already underway.
+	drainChan     chan struct{}
+	state         transportState
+	activeStreams map[uint32]*Stream
+	// idle is the time instant when the connection went idle.
+	// This is either the beginning of the connection or when the number of
+	// RPCs go down to 0.
+	// When the connection is busy, this value is set to 0.
+	idle time.Time
+
+	// Fields below are for channelz metric collection.
+	channelzID int64 // channelz unique identification number
+	czData     *channelzData
+	bufferPool *bufferPool
+
+	connectionID uint64
+}
+
+// NewServerTransport creates a http2 transport with conn and configuration
+// options from config.
+//
+// It returns a non-nil transport and a nil error on success. On failure, it
+// returns a non-nil transport and a nil-error. For a special case where the
+// underlying conn gets closed before the client preface could be read, it
+// returns a nil transport and a nil error.
+func NewServerTransport(conn net.Conn, config *ServerConfig) (_ ServerTransport, err error) {
+	var authInfo credentials.AuthInfo
+	rawConn := conn
+	if config.Credentials != nil {
+		var err error
+		conn, authInfo, err = config.Credentials.ServerHandshake(rawConn)
+		if err != nil {
+			// ErrConnDispatched means that the connection was dispatched away
+			// from gRPC; those connections should be left open. io.EOF means
+			// the connection was closed before handshaking completed, which can
+			// happen naturally from probers. Return these errors directly.
+			if err == credentials.ErrConnDispatched || err == io.EOF {
+				return nil, err
+			}
+			return nil, connectionErrorf(false, err, "ServerHandshake(%q) failed: %v", rawConn.RemoteAddr(), err)
+		}
+	}
+	writeBufSize := config.WriteBufferSize
+	readBufSize := config.ReadBufferSize
+	maxHeaderListSize := defaultServerMaxHeaderListSize
+	if config.MaxHeaderListSize != nil {
+		maxHeaderListSize = *config.MaxHeaderListSize
+	}
+	framer := newFramer(conn, writeBufSize, readBufSize, maxHeaderListSize)
+	// Send initial settings as connection preface to client.
+	isettings := []http2.Setting{{
+		ID:  http2.SettingMaxFrameSize,
+		Val: http2MaxFrameLen,
+	}}
+	// TODO(zhaoq): Have a better way to signal "no limit" because 0 is
+	// permitted in the HTTP2 spec.
+	maxStreams := config.MaxStreams
+	if maxStreams == 0 {
+		maxStreams = math.MaxUint32
+	} else {
+		isettings = append(isettings, http2.Setting{
+			ID:  http2.SettingMaxConcurrentStreams,
+			Val: maxStreams,
+		})
+	}
+	dynamicWindow := true
+	iwz := int32(initialWindowSize)
+	if config.InitialWindowSize >= defaultWindowSize {
+		iwz = config.InitialWindowSize
+		dynamicWindow = false
+	}
+	icwz := int32(initialWindowSize)
+	if config.InitialConnWindowSize >= defaultWindowSize {
+		icwz = config.InitialConnWindowSize
+		dynamicWindow = false
+	}
+	if iwz != defaultWindowSize {
+		isettings = append(isettings, http2.Setting{
+			ID:  http2.SettingInitialWindowSize,
+			Val: uint32(iwz)})
+	}
+	if config.MaxHeaderListSize != nil {
+		isettings = append(isettings, http2.Setting{
+			ID:  http2.SettingMaxHeaderListSize,
+			Val: *config.MaxHeaderListSize,
+		})
+	}
+	if config.HeaderTableSize != nil {
+		isettings = append(isettings, http2.Setting{
+			ID:  http2.SettingHeaderTableSize,
+			Val: *config.HeaderTableSize,
+		})
+	}
+	if err := framer.fr.WriteSettings(isettings...); err != nil {
+		return nil, connectionErrorf(false, err, "transport: %v", err)
+	}
+	// Adjust the connection flow control window if needed.
+	if delta := uint32(icwz - defaultWindowSize); delta > 0 {
+		if err := framer.fr.WriteWindowUpdate(0, delta); err != nil {
+			return nil, connectionErrorf(false, err, "transport: %v", err)
+		}
+	}
+	kp := config.KeepaliveParams
+	if kp.MaxConnectionIdle == 0 {
+		kp.MaxConnectionIdle = defaultMaxConnectionIdle
+	}
+	if kp.MaxConnectionAge == 0 {
+		kp.MaxConnectionAge = defaultMaxConnectionAge
+	}
+	// Add a jitter to MaxConnectionAge.
+	kp.MaxConnectionAge += getJitter(kp.MaxConnectionAge)
+	if kp.MaxConnectionAgeGrace == 0 {
+		kp.MaxConnectionAgeGrace = defaultMaxConnectionAgeGrace
+	}
+	if kp.Time == 0 {
+		kp.Time = defaultServerKeepaliveTime
+	}
+	if kp.Timeout == 0 {
+		kp.Timeout = defaultServerKeepaliveTimeout
+	}
+	kep := config.KeepalivePolicy
+	if kep.MinTime == 0 {
+		kep.MinTime = defaultKeepalivePolicyMinTime
+	}
+
+	done := make(chan struct{})
+	t := &http2Server{
+		ctx:               setConnection(context.Background(), rawConn),
+		done:              done,
+		conn:              conn,
+		remoteAddr:        conn.RemoteAddr(),
+		localAddr:         conn.LocalAddr(),
+		authInfo:          authInfo,
+		framer:            framer,
+		readerDone:        make(chan struct{}),
+		writerDone:        make(chan struct{}),
+		maxStreams:        maxStreams,
+		inTapHandle:       config.InTapHandle,
+		fc:                &trInFlow{limit: uint32(icwz)},
+		state:             reachable,
+		activeStreams:     make(map[uint32]*Stream),
+		stats:             config.StatsHandler,
+		kp:                kp,
+		idle:              time.Now(),
+		kep:               kep,
+		initialWindowSize: iwz,
+		czData:            new(channelzData),
+		bufferPool:        newBufferPool(),
+	}
+	t.controlBuf = newControlBuffer(t.done)
+	if dynamicWindow {
+		t.bdpEst = &bdpEstimator{
+			bdp:               initialWindowSize,
+			updateFlowControl: t.updateFlowControl,
+		}
+	}
+	if t.stats != nil {
+		t.ctx = t.stats.TagConn(t.ctx, &stats.ConnTagInfo{
+			RemoteAddr: t.remoteAddr,
+			LocalAddr:  t.localAddr,
+		})
+		connBegin := &stats.ConnBegin{}
+		t.stats.HandleConn(t.ctx, connBegin)
+	}
+	if channelz.IsOn() {
+		t.channelzID = channelz.RegisterNormalSocket(t, config.ChannelzParentID, fmt.Sprintf("%s -> %s", t.remoteAddr, t.localAddr))
+	}
+
+	t.connectionID = atomic.AddUint64(&serverConnectionCounter, 1)
+
+	t.framer.writer.Flush()
+
+	defer func() {
+		if err != nil {
+			t.Close()
+		}
+	}()
+
+	// Check the validity of client preface.
+	preface := make([]byte, len(clientPreface))
+	if _, err := io.ReadFull(t.conn, preface); err != nil {
+		// In deployments where a gRPC server runs behind a cloud load balancer
+		// which performs regular TCP level health checks, the connection is
+		// closed immediately by the latter. Skipping the error here will help
+		// reduce log clutter.
+		if err == io.EOF {
+			return nil, nil
+		}
+		return nil, connectionErrorf(false, err, "transport: http2Server.HandleStreams failed to receive the preface from client: %v", err)
+	}
+	if !bytes.Equal(preface, clientPreface) {
+		return nil, connectionErrorf(false, nil, "transport: http2Server.HandleStreams received bogus greeting from client: %q", preface)
+	}
+
+	frame, err := t.framer.fr.ReadFrame()
+	if err == io.EOF || err == io.ErrUnexpectedEOF {
+		return nil, err
+	}
+	if err != nil {
+		return nil, connectionErrorf(false, err, "transport: http2Server.HandleStreams failed to read initial settings frame: %v", err)
+	}
+	atomic.StoreInt64(&t.lastRead, time.Now().UnixNano())
+	sf, ok := frame.(*http2.SettingsFrame)
+	if !ok {
+		return nil, connectionErrorf(false, nil, "transport: http2Server.HandleStreams saw invalid preface type %T from client", frame)
+	}
+	t.handleSettings(sf)
+
+	go func() {
+		t.loopy = newLoopyWriter(serverSide, t.framer, t.controlBuf, t.bdpEst)
+		t.loopy.ssGoAwayHandler = t.outgoingGoAwayHandler
+		if err := t.loopy.run(); err != nil {
+			if logger.V(logLevel) {
+				logger.Errorf("transport: loopyWriter.run returning. Err: %v", err)
+			}
+		}
+		t.conn.Close()
+		t.controlBuf.finish()
+		close(t.writerDone)
+	}()
+	go t.keepalive()
+	return t, nil
+}
+
+// operateHeader takes action on the decoded headers.
+func (t *http2Server) operateHeaders(frame *http2.MetaHeadersFrame, handle func(*Stream), traceCtx func(context.Context, string) context.Context) (fatal bool) {
+	streamID := frame.Header().StreamID
+
+	// frame.Truncated is set to true when framer detects that the current header
+	// list size hits MaxHeaderListSize limit.
+	if frame.Truncated {
+		t.controlBuf.put(&cleanupStream{
+			streamID: streamID,
+			rst:      true,
+			rstCode:  http2.ErrCodeFrameSize,
+			onWrite:  func() {},
+		})
+		return false
+	}
+
+	buf := newRecvBuffer()
+	s := &Stream{
+		id:  streamID,
+		st:  t,
+		buf: buf,
+		fc:  &inFlow{limit: uint32(t.initialWindowSize)},
+	}
+
+	var (
+		// If a gRPC Response-Headers has already been received, then it means
+		// that the peer is speaking gRPC and we are in gRPC mode.
+		isGRPC     = false
+		mdata      = make(map[string][]string)
+		httpMethod string
+		// headerError is set if an error is encountered while parsing the headers
+		headerError bool
+
+		timeoutSet bool
+		timeout    time.Duration
+	)
+
+	for _, hf := range frame.Fields {
+		switch hf.Name {
+		case "content-type":
+			contentSubtype, validContentType := grpcutil.ContentSubtype(hf.Value)
+			if !validContentType {
+				break
+			}
+			mdata[hf.Name] = append(mdata[hf.Name], hf.Value)
+			s.contentSubtype = contentSubtype
+			isGRPC = true
+		case "grpc-encoding":
+			s.recvCompress = hf.Value
+		case ":method":
+			httpMethod = hf.Value
+		case ":path":
+			s.method = hf.Value
+		case "grpc-timeout":
+			timeoutSet = true
+			var err error
+			if timeout, err = decodeTimeout(hf.Value); err != nil {
+				headerError = true
+			}
+		default:
+			if isReservedHeader(hf.Name) && !isWhitelistedHeader(hf.Name) {
+				break
+			}
+			v, err := decodeMetadataHeader(hf.Name, hf.Value)
+			if err != nil {
+				headerError = true
+				logger.Warningf("Failed to decode metadata header (%q, %q): %v", hf.Name, hf.Value, err)
+				break
+			}
+			mdata[hf.Name] = append(mdata[hf.Name], v)
+		}
+	}
+
+	if !isGRPC || headerError {
+		t.controlBuf.put(&cleanupStream{
+			streamID: streamID,
+			rst:      true,
+			rstCode:  http2.ErrCodeProtocol,
+			onWrite:  func() {},
+		})
+		return false
+	}
+
+	if frame.StreamEnded() {
+		// s is just created by the caller. No lock needed.
+		s.state = streamReadDone
+	}
+	if timeoutSet {
+		s.ctx, s.cancel = context.WithTimeout(t.ctx, timeout)
+	} else {
+		s.ctx, s.cancel = context.WithCancel(t.ctx)
+	}
+	pr := &peer.Peer{
+		Addr: t.remoteAddr,
+	}
+	// Attach Auth info if there is any.
+	if t.authInfo != nil {
+		pr.AuthInfo = t.authInfo
+	}
+	s.ctx = peer.NewContext(s.ctx, pr)
+	// Attach the received metadata to the context.
+	if len(mdata) > 0 {
+		s.ctx = metadata.NewIncomingContext(s.ctx, mdata)
+		if statsTags := mdata["grpc-tags-bin"]; len(statsTags) > 0 {
+			s.ctx = stats.SetIncomingTags(s.ctx, []byte(statsTags[len(statsTags)-1]))
+		}
+		if statsTrace := mdata["grpc-trace-bin"]; len(statsTrace) > 0 {
+			s.ctx = stats.SetIncomingTrace(s.ctx, []byte(statsTrace[len(statsTrace)-1]))
+		}
+	}
+	t.mu.Lock()
+	if t.state != reachable {
+		t.mu.Unlock()
+		s.cancel()
+		return false
+	}
+	if uint32(len(t.activeStreams)) >= t.maxStreams {
+		t.mu.Unlock()
+		t.controlBuf.put(&cleanupStream{
+			streamID: streamID,
+			rst:      true,
+			rstCode:  http2.ErrCodeRefusedStream,
+			onWrite:  func() {},
+		})
+		s.cancel()
+		return false
+	}
+	if streamID%2 != 1 || streamID <= t.maxStreamID {
+		t.mu.Unlock()
+		// illegal gRPC stream id.
+		if logger.V(logLevel) {
+			logger.Errorf("transport: http2Server.HandleStreams received an illegal stream id: %v", streamID)
+		}
+		s.cancel()
+		return true
+	}
+	t.maxStreamID = streamID
+	if httpMethod != http.MethodPost {
+		t.mu.Unlock()
+		if logger.V(logLevel) {
+			logger.Infof("transport: http2Server.operateHeaders parsed a :method field: %v which should be POST", httpMethod)
+		}
+		t.controlBuf.put(&cleanupStream{
+			streamID: streamID,
+			rst:      true,
+			rstCode:  http2.ErrCodeProtocol,
+			onWrite:  func() {},
+		})
+		s.cancel()
+		return false
+	}
+	if t.inTapHandle != nil {
+		var err error
+		if s.ctx, err = t.inTapHandle(s.ctx, &tap.Info{FullMethodName: s.method}); err != nil {
+			t.mu.Unlock()
+			if logger.V(logLevel) {
+				logger.Infof("transport: http2Server.operateHeaders got an error from InTapHandle: %v", err)
+			}
+			stat, ok := status.FromError(err)
+			if !ok {
+				stat = status.New(codes.PermissionDenied, err.Error())
+			}
+			t.controlBuf.put(&earlyAbortStream{
+				streamID:       s.id,
+				contentSubtype: s.contentSubtype,
+				status:         stat,
+			})
+			return false
+		}
+	}
+	t.activeStreams[streamID] = s
+	if len(t.activeStreams) == 1 {
+		t.idle = time.Time{}
+	}
+	t.mu.Unlock()
+	if channelz.IsOn() {
+		atomic.AddInt64(&t.czData.streamsStarted, 1)
+		atomic.StoreInt64(&t.czData.lastStreamCreatedTime, time.Now().UnixNano())
+	}
+	s.requestRead = func(n int) {
+		t.adjustWindow(s, uint32(n))
+	}
+	s.ctx = traceCtx(s.ctx, s.method)
+	if t.stats != nil {
+		s.ctx = t.stats.TagRPC(s.ctx, &stats.RPCTagInfo{FullMethodName: s.method})
+		inHeader := &stats.InHeader{
+			FullMethod:  s.method,
+			RemoteAddr:  t.remoteAddr,
+			LocalAddr:   t.localAddr,
+			Compression: s.recvCompress,
+			WireLength:  int(frame.Header().Length),
+			Header:      metadata.MD(mdata).Copy(),
+		}
+		t.stats.HandleRPC(s.ctx, inHeader)
+	}
+	s.ctxDone = s.ctx.Done()
+	s.wq = newWriteQuota(defaultWriteQuota, s.ctxDone)
+	s.trReader = &transportReader{
+		reader: &recvBufferReader{
+			ctx:        s.ctx,
+			ctxDone:    s.ctxDone,
+			recv:       s.buf,
+			freeBuffer: t.bufferPool.put,
+		},
+		windowHandler: func(n int) {
+			t.updateWindow(s, uint32(n))
+		},
+	}
+	// Register the stream with loopy.
+	t.controlBuf.put(&registerStream{
+		streamID: s.id,
+		wq:       s.wq,
+	})
+	handle(s)
+	return false
+}
+
+// HandleStreams receives incoming streams using the given handler. This is
+// typically run in a separate goroutine.
+// traceCtx attaches trace to ctx and returns the new context.
+func (t *http2Server) HandleStreams(handle func(*Stream), traceCtx func(context.Context, string) context.Context) {
+	defer close(t.readerDone)
+	for {
+		t.controlBuf.throttle()
+		frame, err := t.framer.fr.ReadFrame()
+		atomic.StoreInt64(&t.lastRead, time.Now().UnixNano())
+		if err != nil {
+			if se, ok := err.(http2.StreamError); ok {
+				if logger.V(logLevel) {
+					logger.Warningf("transport: http2Server.HandleStreams encountered http2.StreamError: %v", se)
+				}
+				t.mu.Lock()
+				s := t.activeStreams[se.StreamID]
+				t.mu.Unlock()
+				if s != nil {
+					t.closeStream(s, true, se.Code, false)
+				} else {
+					t.controlBuf.put(&cleanupStream{
+						streamID: se.StreamID,
+						rst:      true,
+						rstCode:  se.Code,
+						onWrite:  func() {},
+					})
+				}
+				continue
+			}
+			if err == io.EOF || err == io.ErrUnexpectedEOF {
+				t.Close()
+				return
+			}
+			if logger.V(logLevel) {
+				logger.Warningf("transport: http2Server.HandleStreams failed to read frame: %v", err)
+			}
+			t.Close()
+			return
+		}
+		switch frame := frame.(type) {
+		case *http2.MetaHeadersFrame:
+			if t.operateHeaders(frame, handle, traceCtx) {
+				t.Close()
+				break
+			}
+		case *http2.DataFrame:
+			t.handleData(frame)
+		case *http2.RSTStreamFrame:
+			t.handleRSTStream(frame)
+		case *http2.SettingsFrame:
+			t.handleSettings(frame)
+		case *http2.PingFrame:
+			t.handlePing(frame)
+		case *http2.WindowUpdateFrame:
+			t.handleWindowUpdate(frame)
+		case *http2.GoAwayFrame:
+			// TODO: Handle GoAway from the client appropriately.
+		default:
+			if logger.V(logLevel) {
+				logger.Errorf("transport: http2Server.HandleStreams found unhandled frame type %v.", frame)
+			}
+		}
+	}
+}
+
+func (t *http2Server) getStream(f http2.Frame) (*Stream, bool) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if t.activeStreams == nil {
+		// The transport is closing.
+		return nil, false
+	}
+	s, ok := t.activeStreams[f.Header().StreamID]
+	if !ok {
+		// The stream is already done.
+		return nil, false
+	}
+	return s, true
+}
+
+// adjustWindow sends out extra window update over the initial window size
+// of stream if the application is requesting data larger in size than
+// the window.
+func (t *http2Server) adjustWindow(s *Stream, n uint32) {
+	if w := s.fc.maybeAdjust(n); w > 0 {
+		t.controlBuf.put(&outgoingWindowUpdate{streamID: s.id, increment: w})
+	}
+
+}
+
+// updateWindow adjusts the inbound quota for the stream and the transport.
+// Window updates will deliver to the controller for sending when
+// the cumulative quota exceeds the corresponding threshold.
+func (t *http2Server) updateWindow(s *Stream, n uint32) {
+	if w := s.fc.onRead(n); w > 0 {
+		t.controlBuf.put(&outgoingWindowUpdate{streamID: s.id,
+			increment: w,
+		})
+	}
+}
+
+// updateFlowControl updates the incoming flow control windows
+// for the transport and the stream based on the current bdp
+// estimation.
+func (t *http2Server) updateFlowControl(n uint32) {
+	t.mu.Lock()
+	for _, s := range t.activeStreams {
+		s.fc.newLimit(n)
+	}
+	t.initialWindowSize = int32(n)
+	t.mu.Unlock()
+	t.controlBuf.put(&outgoingWindowUpdate{
+		streamID:  0,
+		increment: t.fc.newLimit(n),
+	})
+	t.controlBuf.put(&outgoingSettings{
+		ss: []http2.Setting{
+			{
+				ID:  http2.SettingInitialWindowSize,
+				Val: n,
+			},
+		},
+	})
+
+}
+
+func (t *http2Server) handleData(f *http2.DataFrame) {
+	size := f.Header().Length
+	var sendBDPPing bool
+	if t.bdpEst != nil {
+		sendBDPPing = t.bdpEst.add(size)
+	}
+	// Decouple connection's flow control from application's read.
+	// An update on connection's flow control should not depend on
+	// whether user application has read the data or not. Such a
+	// restriction is already imposed on the stream's flow control,
+	// and therefore the sender will be blocked anyways.
+	// Decoupling the connection flow control will prevent other
+	// active(fast) streams from starving in presence of slow or
+	// inactive streams.
+	if w := t.fc.onData(size); w > 0 {
+		t.controlBuf.put(&outgoingWindowUpdate{
+			streamID:  0,
+			increment: w,
+		})
+	}
+	if sendBDPPing {
+		// Avoid excessive ping detection (e.g. in an L7 proxy)
+		// by sending a window update prior to the BDP ping.
+		if w := t.fc.reset(); w > 0 {
+			t.controlBuf.put(&outgoingWindowUpdate{
+				streamID:  0,
+				increment: w,
+			})
+		}
+		t.controlBuf.put(bdpPing)
+	}
+	// Select the right stream to dispatch.
+	s, ok := t.getStream(f)
+	if !ok {
+		return
+	}
+	if s.getState() == streamReadDone {
+		t.closeStream(s, true, http2.ErrCodeStreamClosed, false)
+		return
+	}
+	if size > 0 {
+		if err := s.fc.onData(size); err != nil {
+			t.closeStream(s, true, http2.ErrCodeFlowControl, false)
+			return
+		}
+		if f.Header().Flags.Has(http2.FlagDataPadded) {
+			if w := s.fc.onRead(size - uint32(len(f.Data()))); w > 0 {
+				t.controlBuf.put(&outgoingWindowUpdate{s.id, w})
+			}
+		}
+		// TODO(bradfitz, zhaoq): A copy is required here because there is no
+		// guarantee f.Data() is consumed before the arrival of next frame.
+		// Can this copy be eliminated?
+		if len(f.Data()) > 0 {
+			buffer := t.bufferPool.get()
+			buffer.Reset()
+			buffer.Write(f.Data())
+			s.write(recvMsg{buffer: buffer})
+		}
+	}
+	if f.Header().Flags.Has(http2.FlagDataEndStream) {
+		// Received the end of stream from the client.
+		s.compareAndSwapState(streamActive, streamReadDone)
+		s.write(recvMsg{err: io.EOF})
+	}
+}
+
+func (t *http2Server) handleRSTStream(f *http2.RSTStreamFrame) {
+	// If the stream is not deleted from the transport's active streams map, then do a regular close stream.
+	if s, ok := t.getStream(f); ok {
+		t.closeStream(s, false, 0, false)
+		return
+	}
+	// If the stream is already deleted from the active streams map, then put a cleanupStream item into controlbuf to delete the stream from loopy writer's established streams map.
+	t.controlBuf.put(&cleanupStream{
+		streamID: f.Header().StreamID,
+		rst:      false,
+		rstCode:  0,
+		onWrite:  func() {},
+	})
+}
+
+func (t *http2Server) handleSettings(f *http2.SettingsFrame) {
+	if f.IsAck() {
+		return
+	}
+	var ss []http2.Setting
+	var updateFuncs []func()
+	f.ForeachSetting(func(s http2.Setting) error {
+		switch s.ID {
+		case http2.SettingMaxHeaderListSize:
+			updateFuncs = append(updateFuncs, func() {
+				t.maxSendHeaderListSize = new(uint32)
+				*t.maxSendHeaderListSize = s.Val
+			})
+		default:
+			ss = append(ss, s)
+		}
+		return nil
+	})
+	t.controlBuf.executeAndPut(func(interface{}) bool {
+		for _, f := range updateFuncs {
+			f()
+		}
+		return true
+	}, &incomingSettings{
+		ss: ss,
+	})
+}
+
+const (
+	maxPingStrikes     = 2
+	defaultPingTimeout = 2 * time.Hour
+)
+
+func (t *http2Server) handlePing(f *http2.PingFrame) {
+	if f.IsAck() {
+		if f.Data == goAwayPing.data && t.drainChan != nil {
+			close(t.drainChan)
+			return
+		}
+		// Maybe it's a BDP ping.
+		if t.bdpEst != nil {
+			t.bdpEst.calculate(f.Data)
+		}
+		return
+	}
+	pingAck := &ping{ack: true}
+	copy(pingAck.data[:], f.Data[:])
+	t.controlBuf.put(pingAck)
+
+	now := time.Now()
+	defer func() {
+		t.lastPingAt = now
+	}()
+	// A reset ping strikes means that we don't need to check for policy
+	// violation for this ping and the pingStrikes counter should be set
+	// to 0.
+	if atomic.CompareAndSwapUint32(&t.resetPingStrikes, 1, 0) {
+		t.pingStrikes = 0
+		return
+	}
+	t.mu.Lock()
+	ns := len(t.activeStreams)
+	t.mu.Unlock()
+	if ns < 1 && !t.kep.PermitWithoutStream {
+		// Keepalive shouldn't be active thus, this new ping should
+		// have come after at least defaultPingTimeout.
+		if t.lastPingAt.Add(defaultPingTimeout).After(now) {
+			t.pingStrikes++
+		}
+	} else {
+		// Check if keepalive policy is respected.
+		if t.lastPingAt.Add(t.kep.MinTime).After(now) {
+			t.pingStrikes++
+		}
+	}
+
+	if t.pingStrikes > maxPingStrikes {
+		// Send goaway and close the connection.
+		if logger.V(logLevel) {
+			logger.Errorf("transport: Got too many pings from the client, closing the connection.")
+		}
+		t.controlBuf.put(&goAway{code: http2.ErrCodeEnhanceYourCalm, debugData: []byte("too_many_pings"), closeConn: true})
+	}
+}
+
+func (t *http2Server) handleWindowUpdate(f *http2.WindowUpdateFrame) {
+	t.controlBuf.put(&incomingWindowUpdate{
+		streamID:  f.Header().StreamID,
+		increment: f.Increment,
+	})
+}
+
+func appendHeaderFieldsFromMD(headerFields []hpack.HeaderField, md metadata.MD) []hpack.HeaderField {
+	for k, vv := range md {
+		if isReservedHeader(k) {
+			// Clients don't tolerate reading restricted headers after some non restricted ones were sent.
+			continue
+		}
+		for _, v := range vv {
+			headerFields = append(headerFields, hpack.HeaderField{Name: k, Value: encodeMetadataHeader(k, v)})
+		}
+	}
+	return headerFields
+}
+
+func (t *http2Server) checkForHeaderListSize(it interface{}) bool {
+	if t.maxSendHeaderListSize == nil {
+		return true
+	}
+	hdrFrame := it.(*headerFrame)
+	var sz int64
+	for _, f := range hdrFrame.hf {
+		if sz += int64(f.Size()); sz > int64(*t.maxSendHeaderListSize) {
+			if logger.V(logLevel) {
+				logger.Errorf("header list size to send violates the maximum size (%d bytes) set by client", *t.maxSendHeaderListSize)
+			}
+			return false
+		}
+	}
+	return true
+}
+
+// WriteHeader sends the header metadata md back to the client.
+func (t *http2Server) WriteHeader(s *Stream, md metadata.MD) error {
+	if s.updateHeaderSent() || s.getState() == streamDone {
+		return ErrIllegalHeaderWrite
+	}
+	s.hdrMu.Lock()
+	if md.Len() > 0 {
+		if s.header.Len() > 0 {
+			s.header = metadata.Join(s.header, md)
+		} else {
+			s.header = md
+		}
+	}
+	if err := t.writeHeaderLocked(s); err != nil {
+		s.hdrMu.Unlock()
+		return err
+	}
+	s.hdrMu.Unlock()
+	return nil
+}
+
+func (t *http2Server) setResetPingStrikes() {
+	atomic.StoreUint32(&t.resetPingStrikes, 1)
+}
+
+func (t *http2Server) writeHeaderLocked(s *Stream) error {
+	// TODO(mmukhi): Benchmark if the performance gets better if count the metadata and other header fields
+	// first and create a slice of that exact size.
+	headerFields := make([]hpack.HeaderField, 0, 2) // at least :status, content-type will be there if none else.
+	headerFields = append(headerFields, hpack.HeaderField{Name: ":status", Value: "200"})
+	headerFields = append(headerFields, hpack.HeaderField{Name: "content-type", Value: grpcutil.ContentType(s.contentSubtype)})
+	if s.sendCompress != "" {
+		headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-encoding", Value: s.sendCompress})
+	}
+	headerFields = appendHeaderFieldsFromMD(headerFields, s.header)
+	success, err := t.controlBuf.executeAndPut(t.checkForHeaderListSize, &headerFrame{
+		streamID:  s.id,
+		hf:        headerFields,
+		endStream: false,
+		onWrite:   t.setResetPingStrikes,
+	})
+	if !success {
+		if err != nil {
+			return err
+		}
+		t.closeStream(s, true, http2.ErrCodeInternal, false)
+		return ErrHeaderListSizeLimitViolation
+	}
+	if t.stats != nil {
+		// Note: Headers are compressed with hpack after this call returns.
+		// No WireLength field is set here.
+		outHeader := &stats.OutHeader{
+			Header:      s.header.Copy(),
+			Compression: s.sendCompress,
+		}
+		t.stats.HandleRPC(s.Context(), outHeader)
+	}
+	return nil
+}
+
+// WriteStatus sends stream status to the client and terminates the stream.
+// There is no further I/O operations being able to perform on this stream.
+// TODO(zhaoq): Now it indicates the end of entire stream. Revisit if early
+// OK is adopted.
+func (t *http2Server) WriteStatus(s *Stream, st *status.Status) error {
+	if s.getState() == streamDone {
+		return nil
+	}
+	s.hdrMu.Lock()
+	// TODO(mmukhi): Benchmark if the performance gets better if count the metadata and other header fields
+	// first and create a slice of that exact size.
+	headerFields := make([]hpack.HeaderField, 0, 2) // grpc-status and grpc-message will be there if none else.
+	if !s.updateHeaderSent() {                      // No headers have been sent.
+		if len(s.header) > 0 { // Send a separate header frame.
+			if err := t.writeHeaderLocked(s); err != nil {
+				s.hdrMu.Unlock()
+				return err
+			}
+		} else { // Send a trailer only response.
+			headerFields = append(headerFields, hpack.HeaderField{Name: ":status", Value: "200"})
+			headerFields = append(headerFields, hpack.HeaderField{Name: "content-type", Value: grpcutil.ContentType(s.contentSubtype)})
+		}
+	}
+	headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-status", Value: strconv.Itoa(int(st.Code()))})
+	headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-message", Value: encodeGrpcMessage(st.Message())})
+
+	if p := st.Proto(); p != nil && len(p.Details) > 0 {
+		stBytes, err := proto.Marshal(p)
+		if err != nil {
+			// TODO: return error instead, when callers are able to handle it.
+			logger.Errorf("transport: failed to marshal rpc status: %v, error: %v", p, err)
+		} else {
+			headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-status-details-bin", Value: encodeBinHeader(stBytes)})
+		}
+	}
+
+	// Attach the trailer metadata.
+	headerFields = appendHeaderFieldsFromMD(headerFields, s.trailer)
+	trailingHeader := &headerFrame{
+		streamID:  s.id,
+		hf:        headerFields,
+		endStream: true,
+		onWrite:   t.setResetPingStrikes,
+	}
+	s.hdrMu.Unlock()
+	success, err := t.controlBuf.execute(t.checkForHeaderListSize, trailingHeader)
+	if !success {
+		if err != nil {
+			return err
+		}
+		t.closeStream(s, true, http2.ErrCodeInternal, false)
+		return ErrHeaderListSizeLimitViolation
+	}
+	// Send a RST_STREAM after the trailers if the client has not already half-closed.
+	rst := s.getState() == streamActive
+	t.finishStream(s, rst, http2.ErrCodeNo, trailingHeader, true)
+	if t.stats != nil {
+		// Note: The trailer fields are compressed with hpack after this call returns.
+		// No WireLength field is set here.
+		t.stats.HandleRPC(s.Context(), &stats.OutTrailer{
+			Trailer: s.trailer.Copy(),
+		})
+	}
+	return nil
+}
+
+// Write converts the data into HTTP2 data frame and sends it out. Non-nil error
+// is returns if it fails (e.g., framing error, transport error).
+func (t *http2Server) Write(s *Stream, hdr []byte, data []byte, opts *Options) error {
+	if !s.isHeaderSent() { // Headers haven't been written yet.
+		if err := t.WriteHeader(s, nil); err != nil {
+			if _, ok := err.(ConnectionError); ok {
+				return err
+			}
+			// TODO(mmukhi, dfawley): Make sure this is the right code to return.
+			return status.Errorf(codes.Internal, "transport: %v", err)
+		}
+	} else {
+		// Writing headers checks for this condition.
+		if s.getState() == streamDone {
+			// TODO(mmukhi, dfawley): Should the server write also return io.EOF?
+			s.cancel()
+			select {
+			case <-t.done:
+				return ErrConnClosing
+			default:
+			}
+			return ContextErr(s.ctx.Err())
+		}
+	}
+	df := &dataFrame{
+		streamID:    s.id,
+		h:           hdr,
+		d:           data,
+		onEachWrite: t.setResetPingStrikes,
+	}
+	if err := s.wq.get(int32(len(hdr) + len(data))); err != nil {
+		select {
+		case <-t.done:
+			return ErrConnClosing
+		default:
+		}
+		return ContextErr(s.ctx.Err())
+	}
+	return t.controlBuf.put(df)
+}
+
+// keepalive running in a separate goroutine does the following:
+// 1. Gracefully closes an idle connection after a duration of keepalive.MaxConnectionIdle.
+// 2. Gracefully closes any connection after a duration of keepalive.MaxConnectionAge.
+// 3. Forcibly closes a connection after an additive period of keepalive.MaxConnectionAgeGrace over keepalive.MaxConnectionAge.
+// 4. Makes sure a connection is alive by sending pings with a frequency of keepalive.Time and closes a non-responsive connection
+// after an additional duration of keepalive.Timeout.
+func (t *http2Server) keepalive() {
+	p := &ping{}
+	// True iff a ping has been sent, and no data has been received since then.
+	outstandingPing := false
+	// Amount of time remaining before which we should receive an ACK for the
+	// last sent ping.
+	kpTimeoutLeft := time.Duration(0)
+	// Records the last value of t.lastRead before we go block on the timer.
+	// This is required to check for read activity since then.
+	prevNano := time.Now().UnixNano()
+	// Initialize the different timers to their default values.
+	idleTimer := time.NewTimer(t.kp.MaxConnectionIdle)
+	ageTimer := time.NewTimer(t.kp.MaxConnectionAge)
+	kpTimer := time.NewTimer(t.kp.Time)
+	defer func() {
+		// We need to drain the underlying channel in these timers after a call
+		// to Stop(), only if we are interested in resetting them. Clearly we
+		// are not interested in resetting them here.
+		idleTimer.Stop()
+		ageTimer.Stop()
+		kpTimer.Stop()
+	}()
+
+	for {
+		select {
+		case <-idleTimer.C:
+			t.mu.Lock()
+			idle := t.idle
+			if idle.IsZero() { // The connection is non-idle.
+				t.mu.Unlock()
+				idleTimer.Reset(t.kp.MaxConnectionIdle)
+				continue
+			}
+			val := t.kp.MaxConnectionIdle - time.Since(idle)
+			t.mu.Unlock()
+			if val <= 0 {
+				// The connection has been idle for a duration of keepalive.MaxConnectionIdle or more.
+				// Gracefully close the connection.
+				t.Drain()
+				return
+			}
+			idleTimer.Reset(val)
+		case <-ageTimer.C:
+			t.Drain()
+			ageTimer.Reset(t.kp.MaxConnectionAgeGrace)
+			select {
+			case <-ageTimer.C:
+				// Close the connection after grace period.
+				if logger.V(logLevel) {
+					logger.Infof("transport: closing server transport due to maximum connection age.")
+				}
+				t.Close()
+			case <-t.done:
+			}
+			return
+		case <-kpTimer.C:
+			lastRead := atomic.LoadInt64(&t.lastRead)
+			if lastRead > prevNano {
+				// There has been read activity since the last time we were
+				// here. Setup the timer to fire at kp.Time seconds from
+				// lastRead time and continue.
+				outstandingPing = false
+				kpTimer.Reset(time.Duration(lastRead) + t.kp.Time - time.Duration(time.Now().UnixNano()))
+				prevNano = lastRead
+				continue
+			}
+			if outstandingPing && kpTimeoutLeft <= 0 {
+				if logger.V(logLevel) {
+					logger.Infof("transport: closing server transport due to idleness.")
+				}
+				t.Close()
+				return
+			}
+			if !outstandingPing {
+				if channelz.IsOn() {
+					atomic.AddInt64(&t.czData.kpCount, 1)
+				}
+				t.controlBuf.put(p)
+				kpTimeoutLeft = t.kp.Timeout
+				outstandingPing = true
+			}
+			// The amount of time to sleep here is the minimum of kp.Time and
+			// timeoutLeft. This will ensure that we wait only for kp.Time
+			// before sending out the next ping (for cases where the ping is
+			// acked).
+			sleepDuration := minTime(t.kp.Time, kpTimeoutLeft)
+			kpTimeoutLeft -= sleepDuration
+			kpTimer.Reset(sleepDuration)
+		case <-t.done:
+			return
+		}
+	}
+}
+
+// Close starts shutting down the http2Server transport.
+// TODO(zhaoq): Now the destruction is not blocked on any pending streams. This
+// could cause some resource issue. Revisit this later.
+func (t *http2Server) Close() {
+	t.mu.Lock()
+	if t.state == closing {
+		t.mu.Unlock()
+		return
+	}
+	t.state = closing
+	streams := t.activeStreams
+	t.activeStreams = nil
+	t.mu.Unlock()
+	t.controlBuf.finish()
+	close(t.done)
+	if err := t.conn.Close(); err != nil && logger.V(logLevel) {
+		logger.Infof("transport: error closing conn during Close: %v", err)
+	}
+	if channelz.IsOn() {
+		channelz.RemoveEntry(t.channelzID)
+	}
+	// Cancel all active streams.
+	for _, s := range streams {
+		s.cancel()
+	}
+	if t.stats != nil {
+		connEnd := &stats.ConnEnd{}
+		t.stats.HandleConn(t.ctx, connEnd)
+	}
+}
+
+// deleteStream deletes the stream s from transport's active streams.
+func (t *http2Server) deleteStream(s *Stream, eosReceived bool) {
+	// In case stream sending and receiving are invoked in separate
+	// goroutines (e.g., bi-directional streaming), cancel needs to be
+	// called to interrupt the potential blocking on other goroutines.
+	s.cancel()
+
+	t.mu.Lock()
+	if _, ok := t.activeStreams[s.id]; ok {
+		delete(t.activeStreams, s.id)
+		if len(t.activeStreams) == 0 {
+			t.idle = time.Now()
+		}
+	}
+	t.mu.Unlock()
+
+	if channelz.IsOn() {
+		if eosReceived {
+			atomic.AddInt64(&t.czData.streamsSucceeded, 1)
+		} else {
+			atomic.AddInt64(&t.czData.streamsFailed, 1)
+		}
+	}
+}
+
+// finishStream closes the stream and puts the trailing headerFrame into controlbuf.
+func (t *http2Server) finishStream(s *Stream, rst bool, rstCode http2.ErrCode, hdr *headerFrame, eosReceived bool) {
+	oldState := s.swapState(streamDone)
+	if oldState == streamDone {
+		// If the stream was already done, return.
+		return
+	}
+
+	hdr.cleanup = &cleanupStream{
+		streamID: s.id,
+		rst:      rst,
+		rstCode:  rstCode,
+		onWrite: func() {
+			t.deleteStream(s, eosReceived)
+		},
+	}
+	t.controlBuf.put(hdr)
+}
+
+// closeStream clears the footprint of a stream when the stream is not needed any more.
+func (t *http2Server) closeStream(s *Stream, rst bool, rstCode http2.ErrCode, eosReceived bool) {
+	s.swapState(streamDone)
+	t.deleteStream(s, eosReceived)
+
+	t.controlBuf.put(&cleanupStream{
+		streamID: s.id,
+		rst:      rst,
+		rstCode:  rstCode,
+		onWrite:  func() {},
+	})
+}
+
+func (t *http2Server) RemoteAddr() net.Addr {
+	return t.remoteAddr
+}
+
+func (t *http2Server) Drain() {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if t.drainChan != nil {
+		return
+	}
+	t.drainChan = make(chan struct{})
+	t.controlBuf.put(&goAway{code: http2.ErrCodeNo, debugData: []byte{}, headsUp: true})
+}
+
+var goAwayPing = &ping{data: [8]byte{1, 6, 1, 8, 0, 3, 3, 9}}
+
+// Handles outgoing GoAway and returns true if loopy needs to put itself
+// in draining mode.
+func (t *http2Server) outgoingGoAwayHandler(g *goAway) (bool, error) {
+	t.mu.Lock()
+	if t.state == closing { // TODO(mmukhi): This seems unnecessary.
+		t.mu.Unlock()
+		// The transport is closing.
+		return false, ErrConnClosing
+	}
+	sid := t.maxStreamID
+	if !g.headsUp {
+		// Stop accepting more streams now.
+		t.state = draining
+		if len(t.activeStreams) == 0 {
+			g.closeConn = true
+		}
+		t.mu.Unlock()
+		if err := t.framer.fr.WriteGoAway(sid, g.code, g.debugData); err != nil {
+			return false, err
+		}
+		if g.closeConn {
+			// Abruptly close the connection following the GoAway (via
+			// loopywriter).  But flush out what's inside the buffer first.
+			t.framer.writer.Flush()
+			return false, fmt.Errorf("transport: Connection closing")
+		}
+		return true, nil
+	}
+	t.mu.Unlock()
+	// For a graceful close, send out a GoAway with stream ID of MaxUInt32,
+	// Follow that with a ping and wait for the ack to come back or a timer
+	// to expire. During this time accept new streams since they might have
+	// originated before the GoAway reaches the client.
+	// After getting the ack or timer expiration send out another GoAway this
+	// time with an ID of the max stream server intends to process.
+	if err := t.framer.fr.WriteGoAway(math.MaxUint32, http2.ErrCodeNo, []byte{}); err != nil {
+		return false, err
+	}
+	if err := t.framer.fr.WritePing(false, goAwayPing.data); err != nil {
+		return false, err
+	}
+	go func() {
+		timer := time.NewTimer(time.Minute)
+		defer timer.Stop()
+		select {
+		case <-t.drainChan:
+		case <-timer.C:
+		case <-t.done:
+			return
+		}
+		t.controlBuf.put(&goAway{code: g.code, debugData: g.debugData})
+	}()
+	return false, nil
+}
+
+func (t *http2Server) ChannelzMetric() *channelz.SocketInternalMetric {
+	s := channelz.SocketInternalMetric{
+		StreamsStarted:                   atomic.LoadInt64(&t.czData.streamsStarted),
+		StreamsSucceeded:                 atomic.LoadInt64(&t.czData.streamsSucceeded),
+		StreamsFailed:                    atomic.LoadInt64(&t.czData.streamsFailed),
+		MessagesSent:                     atomic.LoadInt64(&t.czData.msgSent),
+		MessagesReceived:                 atomic.LoadInt64(&t.czData.msgRecv),
+		KeepAlivesSent:                   atomic.LoadInt64(&t.czData.kpCount),
+		LastRemoteStreamCreatedTimestamp: time.Unix(0, atomic.LoadInt64(&t.czData.lastStreamCreatedTime)),
+		LastMessageSentTimestamp:         time.Unix(0, atomic.LoadInt64(&t.czData.lastMsgSentTime)),
+		LastMessageReceivedTimestamp:     time.Unix(0, atomic.LoadInt64(&t.czData.lastMsgRecvTime)),
+		LocalFlowControlWindow:           int64(t.fc.getSize()),
+		SocketOptions:                    channelz.GetSocketOption(t.conn),
+		LocalAddr:                        t.localAddr,
+		RemoteAddr:                       t.remoteAddr,
+		// RemoteName :
+	}
+	if au, ok := t.authInfo.(credentials.ChannelzSecurityInfo); ok {
+		s.Security = au.GetSecurityValue()
+	}
+	s.RemoteFlowControlWindow = t.getOutFlowWindow()
+	return &s
+}
+
+func (t *http2Server) IncrMsgSent() {
+	atomic.AddInt64(&t.czData.msgSent, 1)
+	atomic.StoreInt64(&t.czData.lastMsgSentTime, time.Now().UnixNano())
+}
+
+func (t *http2Server) IncrMsgRecv() {
+	atomic.AddInt64(&t.czData.msgRecv, 1)
+	atomic.StoreInt64(&t.czData.lastMsgRecvTime, time.Now().UnixNano())
+}
+
+func (t *http2Server) getOutFlowWindow() int64 {
+	resp := make(chan uint32, 1)
+	timer := time.NewTimer(time.Second)
+	defer timer.Stop()
+	t.controlBuf.put(&outFlowControlSizeRequest{resp})
+	select {
+	case sz := <-resp:
+		return int64(sz)
+	case <-t.done:
+		return -1
+	case <-timer.C:
+		return -2
+	}
+}
+
+func getJitter(v time.Duration) time.Duration {
+	if v == infinity {
+		return 0
+	}
+	// Generate a jitter between +/- 10% of the value.
+	r := int64(v / 10)
+	j := grpcrand.Int63n(2*r) - r
+	return time.Duration(j)
+}
+
+type connectionKey struct{}
+
+// GetConnection gets the connection from the context.
+func GetConnection(ctx context.Context) net.Conn {
+	conn, _ := ctx.Value(connectionKey{}).(net.Conn)
+	return conn
+}
+
+// SetConnection adds the connection to the context to be able to get
+// information about the destination ip and port for an incoming RPC. This also
+// allows any unary or streaming interceptors to see the connection.
+func setConnection(ctx context.Context, conn net.Conn) context.Context {
+	return context.WithValue(ctx, connectionKey{}, conn)
+}