Add generated file

This PR adds generated files under pkg/client and vendor folder.

vendor/google.golang.org/grpc/transport/bdp_estimator.go

@@ -0,0 +1,140 @@
+/*
+ *
+ * Copyright 2017 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 (
+	"sync"
+	"time"
+)
+
+const (
+	// bdpLimit is the maximum value the flow control windows
+	// will be increased to.
+	bdpLimit = (1 << 20) * 4
+	// alpha is a constant factor used to keep a moving average
+	// of RTTs.
+	alpha = 0.9
+	// If the current bdp sample is greater than or equal to
+	// our beta * our estimated bdp and the current bandwidth
+	// sample is the maximum bandwidth observed so far, we
+	// increase our bbp estimate by a factor of gamma.
+	beta = 0.66
+	// To put our bdp to be smaller than or equal to twice the real BDP,
+	// we should multiply our current sample with 4/3, however to round things out
+	// we use 2 as the multiplication factor.
+	gamma = 2
+)
+
+// Adding arbitrary data to ping so that its ack can be identified.
+// Easter-egg: what does the ping message say?
+var bdpPing = &ping{data: [8]byte{2, 4, 16, 16, 9, 14, 7, 7}}
+
+type bdpEstimator struct {
+	// sentAt is the time when the ping was sent.
+	sentAt time.Time
+
+	mu sync.Mutex
+	// bdp is the current bdp estimate.
+	bdp uint32
+	// sample is the number of bytes received in one measurement cycle.
+	sample uint32
+	// bwMax is the maximum bandwidth noted so far (bytes/sec).
+	bwMax float64
+	// bool to keep track of the beginning of a new measurement cycle.
+	isSent bool
+	// Callback to update the window sizes.
+	updateFlowControl func(n uint32)
+	// sampleCount is the number of samples taken so far.
+	sampleCount uint64
+	// round trip time (seconds)
+	rtt float64
+}
+
+// timesnap registers the time bdp ping was sent out so that
+// network rtt can be calculated when its ack is received.
+// It is called (by controller) when the bdpPing is
+// being written on the wire.
+func (b *bdpEstimator) timesnap(d [8]byte) {
+	if bdpPing.data != d {
+		return
+	}
+	b.sentAt = time.Now()
+}
+
+// add adds bytes to the current sample for calculating bdp.
+// It returns true only if a ping must be sent. This can be used
+// by the caller (handleData) to make decision about batching
+// a window update with it.
+func (b *bdpEstimator) add(n uint32) bool {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	if b.bdp == bdpLimit {
+		return false
+	}
+	if !b.isSent {
+		b.isSent = true
+		b.sample = n
+		b.sentAt = time.Time{}
+		b.sampleCount++
+		return true
+	}
+	b.sample += n
+	return false
+}
+
+// calculate is called when an ack for a bdp ping is received.
+// Here we calculate the current bdp and bandwidth sample and
+// decide if the flow control windows should go up.
+func (b *bdpEstimator) calculate(d [8]byte) {
+	// Check if the ping acked for was the bdp ping.
+	if bdpPing.data != d {
+		return
+	}
+	b.mu.Lock()
+	rttSample := time.Since(b.sentAt).Seconds()
+	if b.sampleCount < 10 {
+		// Bootstrap rtt with an average of first 10 rtt samples.
+		b.rtt += (rttSample - b.rtt) / float64(b.sampleCount)
+	} else {
+		// Heed to the recent past more.
+		b.rtt += (rttSample - b.rtt) * float64(alpha)
+	}
+	b.isSent = false
+	// The number of bytes accumulated so far in the sample is smaller
+	// than or equal to 1.5 times the real BDP on a saturated connection.
+	bwCurrent := float64(b.sample) / (b.rtt * float64(1.5))
+	if bwCurrent > b.bwMax {
+		b.bwMax = bwCurrent
+	}
+	// If the current sample (which is smaller than or equal to the 1.5 times the real BDP) is
+	// greater than or equal to 2/3rd our perceived bdp AND this is the maximum bandwidth seen so far, we
+	// should update our perception of the network BDP.
+	if float64(b.sample) >= beta*float64(b.bdp) && bwCurrent == b.bwMax && b.bdp != bdpLimit {
+		sampleFloat := float64(b.sample)
+		b.bdp = uint32(gamma * sampleFloat)
+		if b.bdp > bdpLimit {
+			b.bdp = bdpLimit
+		}
+		bdp := b.bdp
+		b.mu.Unlock()
+		b.updateFlowControl(bdp)
+		return
+	}
+	b.mu.Unlock()
+}

vendor/google.golang.org/grpc/transport/control.go

@@ -0,0 +1,334 @@
+/*
+ *
+ * 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 (
+	"fmt"
+	"io"
+	"math"
+	"sync"
+	"time"
+
+	"golang.org/x/net/http2"
+	"golang.org/x/net/http2/hpack"
+)
+
+const (
+	// The default value of flow control window size in HTTP2 spec.
+	defaultWindowSize = 65535
+	// The initial window size for flow control.
+	initialWindowSize             = defaultWindowSize // for an RPC
+	infinity                      = time.Duration(math.MaxInt64)
+	defaultClientKeepaliveTime    = infinity
+	defaultClientKeepaliveTimeout = time.Duration(20 * time.Second)
+	defaultMaxStreamsClient       = 100
+	defaultMaxConnectionIdle      = infinity
+	defaultMaxConnectionAge       = infinity
+	defaultMaxConnectionAgeGrace  = infinity
+	defaultServerKeepaliveTime    = time.Duration(2 * time.Hour)
+	defaultServerKeepaliveTimeout = time.Duration(20 * time.Second)
+	defaultKeepalivePolicyMinTime = time.Duration(5 * time.Minute)
+	// max window limit set by HTTP2 Specs.
+	maxWindowSize = math.MaxInt32
+	// defaultLocalSendQuota sets is default value for number of data
+	// bytes that each stream can schedule before some of it being
+	// flushed out.
+	defaultLocalSendQuota = 128 * 1024
+)
+
+// The following defines various control items which could flow through
+// the control buffer of transport. They represent different aspects of
+// control tasks, e.g., flow control, settings, streaming resetting, etc.
+
+type headerFrame struct {
+	streamID  uint32
+	hf        []hpack.HeaderField
+	endStream bool
+}
+
+func (*headerFrame) item() {}
+
+type continuationFrame struct {
+	streamID            uint32
+	endHeaders          bool
+	headerBlockFragment []byte
+}
+
+type dataFrame struct {
+	streamID  uint32
+	endStream bool
+	d         []byte
+	f         func()
+}
+
+func (*dataFrame) item() {}
+
+func (*continuationFrame) item() {}
+
+type windowUpdate struct {
+	streamID  uint32
+	increment uint32
+}
+
+func (*windowUpdate) item() {}
+
+type settings struct {
+	ss []http2.Setting
+}
+
+func (*settings) item() {}
+
+type settingsAck struct {
+}
+
+func (*settingsAck) item() {}
+
+type resetStream struct {
+	streamID uint32
+	code     http2.ErrCode
+}
+
+func (*resetStream) item() {}
+
+type goAway struct {
+	code      http2.ErrCode
+	debugData []byte
+	headsUp   bool
+	closeConn bool
+}
+
+func (*goAway) item() {}
+
+type flushIO struct {
+	closeTr bool
+}
+
+func (*flushIO) item() {}
+
+type ping struct {
+	ack  bool
+	data [8]byte
+}
+
+func (*ping) item() {}
+
+// quotaPool is a pool which accumulates the quota and sends it to acquire()
+// when it is available.
+type quotaPool struct {
+	mu      sync.Mutex
+	c       chan struct{}
+	version uint32
+	quota   int
+}
+
+// newQuotaPool creates a quotaPool which has quota q available to consume.
+func newQuotaPool(q int) *quotaPool {
+	qb := &quotaPool{
+		quota: q,
+		c:     make(chan struct{}, 1),
+	}
+	return qb
+}
+
+// add cancels the pending quota sent on acquired, incremented by v and sends
+// it back on acquire.
+func (qb *quotaPool) add(v int) {
+	qb.mu.Lock()
+	defer qb.mu.Unlock()
+	qb.lockedAdd(v)
+}
+
+func (qb *quotaPool) lockedAdd(v int) {
+	var wakeUp bool
+	if qb.quota <= 0 {
+		wakeUp = true // Wake up potential waiters.
+	}
+	qb.quota += v
+	if wakeUp && qb.quota > 0 {
+		select {
+		case qb.c <- struct{}{}:
+		default:
+		}
+	}
+}
+
+func (qb *quotaPool) addAndUpdate(v int) {
+	qb.mu.Lock()
+	qb.lockedAdd(v)
+	qb.version++
+	qb.mu.Unlock()
+}
+
+func (qb *quotaPool) get(v int, wc waiters) (int, uint32, error) {
+	qb.mu.Lock()
+	if qb.quota > 0 {
+		if v > qb.quota {
+			v = qb.quota
+		}
+		qb.quota -= v
+		ver := qb.version
+		qb.mu.Unlock()
+		return v, ver, nil
+	}
+	qb.mu.Unlock()
+	for {
+		select {
+		case <-wc.ctx.Done():
+			return 0, 0, ContextErr(wc.ctx.Err())
+		case <-wc.tctx.Done():
+			return 0, 0, ErrConnClosing
+		case <-wc.done:
+			return 0, 0, io.EOF
+		case <-wc.goAway:
+			return 0, 0, errStreamDrain
+		case <-qb.c:
+			qb.mu.Lock()
+			if qb.quota > 0 {
+				if v > qb.quota {
+					v = qb.quota
+				}
+				qb.quota -= v
+				ver := qb.version
+				if qb.quota > 0 {
+					select {
+					case qb.c <- struct{}{}:
+					default:
+					}
+				}
+				qb.mu.Unlock()
+				return v, ver, nil
+
+			}
+			qb.mu.Unlock()
+		}
+	}
+}
+
+func (qb *quotaPool) compareAndExecute(version uint32, success, failure func()) bool {
+	qb.mu.Lock()
+	if version == qb.version {
+		success()
+		qb.mu.Unlock()
+		return true
+	}
+	failure()
+	qb.mu.Unlock()
+	return false
+}
+
+// inFlow deals with inbound flow control
+type inFlow struct {
+	mu sync.Mutex
+	// The inbound flow control limit for pending data.
+	limit uint32
+	// pendingData is the overall data which have been received but not been
+	// consumed by applications.
+	pendingData uint32
+	// The amount of data the application has consumed but grpc has not sent
+	// window update for them. Used to reduce window update frequency.
+	pendingUpdate uint32
+	// delta is the extra window update given by receiver when an application
+	// is reading data bigger in size than the inFlow limit.
+	delta uint32
+}
+
+// newLimit updates the inflow window to a new value n.
+// It assumes that n is always greater than the old limit.
+func (f *inFlow) newLimit(n uint32) uint32 {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	d := n - f.limit
+	f.limit = n
+	return d
+}
+
+func (f *inFlow) maybeAdjust(n uint32) uint32 {
+	if n > uint32(math.MaxInt32) {
+		n = uint32(math.MaxInt32)
+	}
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	// estSenderQuota is the receiver's view of the maximum number of bytes the sender
+	// can send without a window update.
+	estSenderQuota := int32(f.limit - (f.pendingData + f.pendingUpdate))
+	// estUntransmittedData is the maximum number of bytes the sends might not have put
+	// on the wire yet. A value of 0 or less means that we have already received all or
+	// more bytes than the application is requesting to read.
+	estUntransmittedData := int32(n - f.pendingData) // Casting into int32 since it could be negative.
+	// This implies that unless we send a window update, the sender won't be able to send all the bytes
+	// for this message. Therefore we must send an update over the limit since there's an active read
+	// request from the application.
+	if estUntransmittedData > estSenderQuota {
+		// Sender's window shouldn't go more than 2^31 - 1 as speecified in the HTTP spec.
+		if f.limit+n > maxWindowSize {
+			f.delta = maxWindowSize - f.limit
+		} else {
+			// Send a window update for the whole message and not just the difference between
+			// estUntransmittedData and estSenderQuota. This will be helpful in case the message
+			// is padded; We will fallback on the current available window(at least a 1/4th of the limit).
+			f.delta = n
+		}
+		return f.delta
+	}
+	return 0
+}
+
+// onData is invoked when some data frame is received. It updates pendingData.
+func (f *inFlow) onData(n uint32) error {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	f.pendingData += n
+	if f.pendingData+f.pendingUpdate > f.limit+f.delta {
+		return fmt.Errorf("received %d-bytes data exceeding the limit %d bytes", f.pendingData+f.pendingUpdate, f.limit)
+	}
+	return nil
+}
+
+// onRead is invoked when the application reads the data. It returns the window size
+// to be sent to the peer.
+func (f *inFlow) onRead(n uint32) uint32 {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	if f.pendingData == 0 {
+		return 0
+	}
+	f.pendingData -= n
+	if n > f.delta {
+		n -= f.delta
+		f.delta = 0
+	} else {
+		f.delta -= n
+		n = 0
+	}
+	f.pendingUpdate += n
+	if f.pendingUpdate >= f.limit/4 {
+		wu := f.pendingUpdate
+		f.pendingUpdate = 0
+		return wu
+	}
+	return 0
+}
+
+func (f *inFlow) resetPendingUpdate() uint32 {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	n := f.pendingUpdate
+	f.pendingUpdate = 0
+	return n
+}

vendor/google.golang.org/grpc/transport/go16.go

@@ -0,0 +1,51 @@
+// +build go1.6,!go1.7
+
+/*
+ *
+ * Copyright 2016 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 (
+	"net"
+	"net/http"
+
+	"google.golang.org/grpc/codes"
+
+	"golang.org/x/net/context"
+)
+
+// dialContext connects to the address on the named network.
+func dialContext(ctx context.Context, network, address string) (net.Conn, error) {
+	return (&net.Dialer{Cancel: ctx.Done()}).Dial(network, address)
+}
+
+// ContextErr converts the error from context package into a StreamError.
+func ContextErr(err error) StreamError {
+	switch err {
+	case context.DeadlineExceeded:
+		return streamErrorf(codes.DeadlineExceeded, "%v", err)
+	case context.Canceled:
+		return streamErrorf(codes.Canceled, "%v", err)
+	}
+	return streamErrorf(codes.Internal, "Unexpected error from context packet: %v", err)
+}
+
+// contextFromRequest returns a background context.
+func contextFromRequest(r *http.Request) context.Context {
+	return context.Background()
+}

vendor/google.golang.org/grpc/transport/go17.go

@@ -0,0 +1,52 @@
+// +build go1.7
+
+/*
+ *
+ * Copyright 2016 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 (
+	"context"
+	"net"
+	"net/http"
+
+	"google.golang.org/grpc/codes"
+
+	netctx "golang.org/x/net/context"
+)
+
+// dialContext connects to the address on the named network.
+func dialContext(ctx context.Context, network, address string) (net.Conn, error) {
+	return (&net.Dialer{}).DialContext(ctx, network, address)
+}
+
+// ContextErr converts the error from context package into a StreamError.
+func ContextErr(err error) StreamError {
+	switch err {
+	case context.DeadlineExceeded, netctx.DeadlineExceeded:
+		return streamErrorf(codes.DeadlineExceeded, "%v", err)
+	case context.Canceled, netctx.Canceled:
+		return streamErrorf(codes.Canceled, "%v", err)
+	}
+	return streamErrorf(codes.Internal, "Unexpected error from context packet: %v", err)
+}
+
+// contextFromRequest returns a context from the HTTP Request.
+func contextFromRequest(r *http.Request) context.Context {
+	return r.Context()
+}

vendor/google.golang.org/grpc/transport/handler_server.go

@@ -0,0 +1,448 @@
+/*
+ *
+ * Copyright 2016 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.
+ *
+ */
+
+// This file is the implementation of a gRPC server using HTTP/2 which
+// uses the standard Go http2 Server implementation (via the
+// http.Handler interface), rather than speaking low-level HTTP/2
+// frames itself. It is the implementation of *grpc.Server.ServeHTTP.
+
+package transport
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/golang/protobuf/proto"
+	"golang.org/x/net/context"
+	"golang.org/x/net/http2"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/peer"
+	"google.golang.org/grpc/stats"
+	"google.golang.org/grpc/status"
+)
+
+// NewServerHandlerTransport returns a ServerTransport handling gRPC
+// from inside an http.Handler. It requires that the http Server
+// supports HTTP/2.
+func NewServerHandlerTransport(w http.ResponseWriter, r *http.Request, stats stats.Handler) (ServerTransport, error) {
+	if r.ProtoMajor != 2 {
+		return nil, errors.New("gRPC requires HTTP/2")
+	}
+	if r.Method != "POST" {
+		return nil, errors.New("invalid gRPC request method")
+	}
+	contentType := r.Header.Get("Content-Type")
+	// TODO: do we assume contentType is lowercase? we did before
+	contentSubtype, validContentType := contentSubtype(contentType)
+	if !validContentType {
+		return nil, errors.New("invalid gRPC request content-type")
+	}
+	if _, ok := w.(http.Flusher); !ok {
+		return nil, errors.New("gRPC requires a ResponseWriter supporting http.Flusher")
+	}
+	if _, ok := w.(http.CloseNotifier); !ok {
+		return nil, errors.New("gRPC requires a ResponseWriter supporting http.CloseNotifier")
+	}
+
+	st := &serverHandlerTransport{
+		rw:             w,
+		req:            r,
+		closedCh:       make(chan struct{}),
+		writes:         make(chan func()),
+		contentType:    contentType,
+		contentSubtype: contentSubtype,
+		stats:          stats,
+	}
+
+	if v := r.Header.Get("grpc-timeout"); v != "" {
+		to, err := decodeTimeout(v)
+		if err != nil {
+			return nil, streamErrorf(codes.Internal, "malformed time-out: %v", err)
+		}
+		st.timeoutSet = true
+		st.timeout = to
+	}
+
+	metakv := []string{"content-type", contentType}
+	if r.Host != "" {
+		metakv = append(metakv, ":authority", r.Host)
+	}
+	for k, vv := range r.Header {
+		k = strings.ToLower(k)
+		if isReservedHeader(k) && !isWhitelistedPseudoHeader(k) {
+			continue
+		}
+		for _, v := range vv {
+			v, err := decodeMetadataHeader(k, v)
+			if err != nil {
+				return nil, streamErrorf(codes.InvalidArgument, "malformed binary metadata: %v", err)
+			}
+			metakv = append(metakv, k, v)
+		}
+	}
+	st.headerMD = metadata.Pairs(metakv...)
+
+	return st, nil
+}
+
+// serverHandlerTransport is an implementation of ServerTransport
+// which replies to exactly one gRPC request (exactly one HTTP request),
+// using the net/http.Handler interface. This http.Handler is guaranteed
+// at this point to be speaking over HTTP/2, so it's able to speak valid
+// gRPC.
+type serverHandlerTransport struct {
+	rw               http.ResponseWriter
+	req              *http.Request
+	timeoutSet       bool
+	timeout          time.Duration
+	didCommonHeaders bool
+
+	headerMD metadata.MD
+
+	closeOnce sync.Once
+	closedCh  chan struct{} // closed on Close
+
+	// writes is a channel of code to run serialized in the
+	// ServeHTTP (HandleStreams) goroutine. The channel is closed
+	// when WriteStatus is called.
+	writes chan func()
+
+	// block concurrent WriteStatus calls
+	// e.g. grpc/(*serverStream).SendMsg/RecvMsg
+	writeStatusMu sync.Mutex
+
+	// we just mirror the request content-type
+	contentType string
+	// we store both contentType and contentSubtype so we don't keep recreating them
+	// TODO make sure this is consistent across handler_server and http2_server
+	contentSubtype string
+
+	stats stats.Handler
+}
+
+func (ht *serverHandlerTransport) Close() error {
+	ht.closeOnce.Do(ht.closeCloseChanOnce)
+	return nil
+}
+
+func (ht *serverHandlerTransport) closeCloseChanOnce() { close(ht.closedCh) }
+
+func (ht *serverHandlerTransport) RemoteAddr() net.Addr { return strAddr(ht.req.RemoteAddr) }
+
+// strAddr is a net.Addr backed by either a TCP "ip:port" string, or
+// the empty string if unknown.
+type strAddr string
+
+func (a strAddr) Network() string {
+	if a != "" {
+		// Per the documentation on net/http.Request.RemoteAddr, if this is
+		// set, it's set to the IP:port of the peer (hence, TCP):
+		// https://golang.org/pkg/net/http/#Request
+		//
+		// If we want to support Unix sockets later, we can
+		// add our own grpc-specific convention within the
+		// grpc codebase to set RemoteAddr to a different
+		// format, or probably better: we can attach it to the
+		// context and use that from serverHandlerTransport.RemoteAddr.
+		return "tcp"
+	}
+	return ""
+}
+
+func (a strAddr) String() string { return string(a) }
+
+// do runs fn in the ServeHTTP goroutine.
+func (ht *serverHandlerTransport) do(fn func()) error {
+	// Avoid a panic writing to closed channel. Imperfect but maybe good enough.
+	select {
+	case <-ht.closedCh:
+		return ErrConnClosing
+	default:
+		select {
+		case ht.writes <- fn:
+			return nil
+		case <-ht.closedCh:
+			return ErrConnClosing
+		}
+	}
+}
+
+func (ht *serverHandlerTransport) WriteStatus(s *Stream, st *status.Status) error {
+	ht.writeStatusMu.Lock()
+	defer ht.writeStatusMu.Unlock()
+
+	err := ht.do(func() {
+		ht.writeCommonHeaders(s)
+
+		// And flush, in case no header or body has been sent yet.
+		// This forces a separation of headers and trailers if this is the
+		// first call (for example, in end2end tests's TestNoService).
+		ht.rw.(http.Flusher).Flush()
+
+		h := ht.rw.Header()
+		h.Set("Grpc-Status", fmt.Sprintf("%d", st.Code()))
+		if m := st.Message(); m != "" {
+			h.Set("Grpc-Message", encodeGrpcMessage(m))
+		}
+
+		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.
+				panic(err)
+			}
+
+			h.Set("Grpc-Status-Details-Bin", encodeBinHeader(stBytes))
+		}
+
+		if md := s.Trailer(); len(md) > 0 {
+			for k, vv := range md {
+				// Clients don't tolerate reading restricted headers after some non restricted ones were sent.
+				if isReservedHeader(k) {
+					continue
+				}
+				for _, v := range vv {
+					// http2 ResponseWriter mechanism to send undeclared Trailers after
+					// the headers have possibly been written.
+					h.Add(http2.TrailerPrefix+k, encodeMetadataHeader(k, v))
+				}
+			}
+		}
+	})
+
+	if err == nil { // transport has not been closed
+		if ht.stats != nil {
+			ht.stats.HandleRPC(s.Context(), &stats.OutTrailer{})
+		}
+		ht.Close()
+		close(ht.writes)
+	}
+	return err
+}
+
+// writeCommonHeaders sets common headers on the first write
+// call (Write, WriteHeader, or WriteStatus).
+func (ht *serverHandlerTransport) writeCommonHeaders(s *Stream) {
+	if ht.didCommonHeaders {
+		return
+	}
+	ht.didCommonHeaders = true
+
+	h := ht.rw.Header()
+	h["Date"] = nil // suppress Date to make tests happy; TODO: restore
+	h.Set("Content-Type", ht.contentType)
+
+	// Predeclare trailers we'll set later in WriteStatus (after the body).
+	// This is a SHOULD in the HTTP RFC, and the way you add (known)
+	// Trailers per the net/http.ResponseWriter contract.
+	// See https://golang.org/pkg/net/http/#ResponseWriter
+	// and https://golang.org/pkg/net/http/#example_ResponseWriter_trailers
+	h.Add("Trailer", "Grpc-Status")
+	h.Add("Trailer", "Grpc-Message")
+	h.Add("Trailer", "Grpc-Status-Details-Bin")
+
+	if s.sendCompress != "" {
+		h.Set("Grpc-Encoding", s.sendCompress)
+	}
+}
+
+func (ht *serverHandlerTransport) Write(s *Stream, hdr []byte, data []byte, opts *Options) error {
+	return ht.do(func() {
+		ht.writeCommonHeaders(s)
+		ht.rw.Write(hdr)
+		ht.rw.Write(data)
+		if !opts.Delay {
+			ht.rw.(http.Flusher).Flush()
+		}
+	})
+}
+
+func (ht *serverHandlerTransport) WriteHeader(s *Stream, md metadata.MD) error {
+	err := ht.do(func() {
+		ht.writeCommonHeaders(s)
+		h := ht.rw.Header()
+		for k, vv := range md {
+			// Clients don't tolerate reading restricted headers after some non restricted ones were sent.
+			if isReservedHeader(k) {
+				continue
+			}
+			for _, v := range vv {
+				v = encodeMetadataHeader(k, v)
+				h.Add(k, v)
+			}
+		}
+		ht.rw.WriteHeader(200)
+		ht.rw.(http.Flusher).Flush()
+	})
+
+	if err == nil {
+		if ht.stats != nil {
+			ht.stats.HandleRPC(s.Context(), &stats.OutHeader{})
+		}
+	}
+	return err
+}
+
+func (ht *serverHandlerTransport) HandleStreams(startStream func(*Stream), traceCtx func(context.Context, string) context.Context) {
+	// With this transport type there will be exactly 1 stream: this HTTP request.
+
+	ctx := contextFromRequest(ht.req)
+	var cancel context.CancelFunc
+	if ht.timeoutSet {
+		ctx, cancel = context.WithTimeout(ctx, ht.timeout)
+	} else {
+		ctx, cancel = context.WithCancel(ctx)
+	}
+
+	// requestOver is closed when either the request's context is done
+	// or the status has been written via WriteStatus.
+	requestOver := make(chan struct{})
+
+	// clientGone receives a single value if peer is gone, either
+	// because the underlying connection is dead or because the
+	// peer sends an http2 RST_STREAM.
+	clientGone := ht.rw.(http.CloseNotifier).CloseNotify()
+	go func() {
+		select {
+		case <-requestOver:
+			return
+		case <-ht.closedCh:
+		case <-clientGone:
+		}
+		cancel()
+	}()
+
+	req := ht.req
+
+	s := &Stream{
+		id:             0, // irrelevant
+		requestRead:    func(int) {},
+		cancel:         cancel,
+		buf:            newRecvBuffer(),
+		st:             ht,
+		method:         req.URL.Path,
+		recvCompress:   req.Header.Get("grpc-encoding"),
+		contentSubtype: ht.contentSubtype,
+	}
+	pr := &peer.Peer{
+		Addr: ht.RemoteAddr(),
+	}
+	if req.TLS != nil {
+		pr.AuthInfo = credentials.TLSInfo{State: *req.TLS}
+	}
+	ctx = metadata.NewIncomingContext(ctx, ht.headerMD)
+	ctx = peer.NewContext(ctx, pr)
+	s.ctx = newContextWithStream(ctx, s)
+	if ht.stats != nil {
+		s.ctx = ht.stats.TagRPC(s.ctx, &stats.RPCTagInfo{FullMethodName: s.method})
+		inHeader := &stats.InHeader{
+			FullMethod:  s.method,
+			RemoteAddr:  ht.RemoteAddr(),
+			Compression: s.recvCompress,
+		}
+		ht.stats.HandleRPC(s.ctx, inHeader)
+	}
+	s.trReader = &transportReader{
+		reader:        &recvBufferReader{ctx: s.ctx, recv: s.buf},
+		windowHandler: func(int) {},
+	}
+
+	// readerDone is closed when the Body.Read-ing goroutine exits.
+	readerDone := make(chan struct{})
+	go func() {
+		defer close(readerDone)
+
+		// TODO: minimize garbage, optimize recvBuffer code/ownership
+		const readSize = 8196
+		for buf := make([]byte, readSize); ; {
+			n, err := req.Body.Read(buf)
+			if n > 0 {
+				s.buf.put(recvMsg{data: buf[:n:n]})
+				buf = buf[n:]
+			}
+			if err != nil {
+				s.buf.put(recvMsg{err: mapRecvMsgError(err)})
+				return
+			}
+			if len(buf) == 0 {
+				buf = make([]byte, readSize)
+			}
+		}
+	}()
+
+	// startStream is provided by the *grpc.Server's serveStreams.
+	// It starts a goroutine serving s and exits immediately.
+	// The goroutine that is started is the one that then calls
+	// into ht, calling WriteHeader, Write, WriteStatus, Close, etc.
+	startStream(s)
+
+	ht.runStream()
+	close(requestOver)
+
+	// Wait for reading goroutine to finish.
+	req.Body.Close()
+	<-readerDone
+}
+
+func (ht *serverHandlerTransport) runStream() {
+	for {
+		select {
+		case fn, ok := <-ht.writes:
+			if !ok {
+				return
+			}
+			fn()
+		case <-ht.closedCh:
+			return
+		}
+	}
+}
+
+func (ht *serverHandlerTransport) Drain() {
+	panic("Drain() is not implemented")
+}
+
+// mapRecvMsgError returns the non-nil err into the appropriate
+// error value as expected by callers of *grpc.parser.recvMsg.
+// In particular, in can only be:
+//   * io.EOF
+//   * io.ErrUnexpectedEOF
+//   * of type transport.ConnectionError
+//   * of type transport.StreamError
+func mapRecvMsgError(err error) error {
+	if err == io.EOF || err == io.ErrUnexpectedEOF {
+		return err
+	}
+	if se, ok := err.(http2.StreamError); ok {
+		if code, ok := http2ErrConvTab[se.Code]; ok {
+			return StreamError{
+				Code: code,
+				Desc: se.Error(),
+			}
+		}
+	}
+	return connectionErrorf(true, err, err.Error())
+}

vendor/google.golang.org/grpc/transport/handler_server_test.go

@@ -0,0 +1,482 @@
+/*
+ *
+ * Copyright 2016 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 (
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"reflect"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/golang/protobuf/proto"
+	dpb "github.com/golang/protobuf/ptypes/duration"
+	"golang.org/x/net/context"
+	epb "google.golang.org/genproto/googleapis/rpc/errdetails"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/status"
+)
+
+func TestHandlerTransport_NewServerHandlerTransport(t *testing.T) {
+	type testCase struct {
+		name    string
+		req     *http.Request
+		wantErr string
+		modrw   func(http.ResponseWriter) http.ResponseWriter
+		check   func(*serverHandlerTransport, *testCase) error
+	}
+	tests := []testCase{
+		{
+			name: "http/1.1",
+			req: &http.Request{
+				ProtoMajor: 1,
+				ProtoMinor: 1,
+			},
+			wantErr: "gRPC requires HTTP/2",
+		},
+		{
+			name: "bad method",
+			req: &http.Request{
+				ProtoMajor: 2,
+				Method:     "GET",
+				Header:     http.Header{},
+				RequestURI: "/",
+			},
+			wantErr: "invalid gRPC request method",
+		},
+		{
+			name: "bad content type",
+			req: &http.Request{
+				ProtoMajor: 2,
+				Method:     "POST",
+				Header: http.Header{
+					"Content-Type": {"application/foo"},
+				},
+				RequestURI: "/service/foo.bar",
+			},
+			wantErr: "invalid gRPC request content-type",
+		},
+		{
+			name: "not flusher",
+			req: &http.Request{
+				ProtoMajor: 2,
+				Method:     "POST",
+				Header: http.Header{
+					"Content-Type": {"application/grpc"},
+				},
+				RequestURI: "/service/foo.bar",
+			},
+			modrw: func(w http.ResponseWriter) http.ResponseWriter {
+				// Return w without its Flush method
+				type onlyCloseNotifier interface {
+					http.ResponseWriter
+					http.CloseNotifier
+				}
+				return struct{ onlyCloseNotifier }{w.(onlyCloseNotifier)}
+			},
+			wantErr: "gRPC requires a ResponseWriter supporting http.Flusher",
+		},
+		{
+			name: "not closenotifier",
+			req: &http.Request{
+				ProtoMajor: 2,
+				Method:     "POST",
+				Header: http.Header{
+					"Content-Type": {"application/grpc"},
+				},
+				RequestURI: "/service/foo.bar",
+			},
+			modrw: func(w http.ResponseWriter) http.ResponseWriter {
+				// Return w without its CloseNotify method
+				type onlyFlusher interface {
+					http.ResponseWriter
+					http.Flusher
+				}
+				return struct{ onlyFlusher }{w.(onlyFlusher)}
+			},
+			wantErr: "gRPC requires a ResponseWriter supporting http.CloseNotifier",
+		},
+		{
+			name: "valid",
+			req: &http.Request{
+				ProtoMajor: 2,
+				Method:     "POST",
+				Header: http.Header{
+					"Content-Type": {"application/grpc"},
+				},
+				URL: &url.URL{
+					Path: "/service/foo.bar",
+				},
+				RequestURI: "/service/foo.bar",
+			},
+			check: func(t *serverHandlerTransport, tt *testCase) error {
+				if t.req != tt.req {
+					return fmt.Errorf("t.req = %p; want %p", t.req, tt.req)
+				}
+				if t.rw == nil {
+					return errors.New("t.rw = nil; want non-nil")
+				}
+				return nil
+			},
+		},
+		{
+			name: "with timeout",
+			req: &http.Request{
+				ProtoMajor: 2,
+				Method:     "POST",
+				Header: http.Header{
+					"Content-Type": []string{"application/grpc"},
+					"Grpc-Timeout": {"200m"},
+				},
+				URL: &url.URL{
+					Path: "/service/foo.bar",
+				},
+				RequestURI: "/service/foo.bar",
+			},
+			check: func(t *serverHandlerTransport, tt *testCase) error {
+				if !t.timeoutSet {
+					return errors.New("timeout not set")
+				}
+				if want := 200 * time.Millisecond; t.timeout != want {
+					return fmt.Errorf("timeout = %v; want %v", t.timeout, want)
+				}
+				return nil
+			},
+		},
+		{
+			name: "with bad timeout",
+			req: &http.Request{
+				ProtoMajor: 2,
+				Method:     "POST",
+				Header: http.Header{
+					"Content-Type": []string{"application/grpc"},
+					"Grpc-Timeout": {"tomorrow"},
+				},
+				URL: &url.URL{
+					Path: "/service/foo.bar",
+				},
+				RequestURI: "/service/foo.bar",
+			},
+			wantErr: `stream error: code = Internal desc = "malformed time-out: transport: timeout unit is not recognized: \"tomorrow\""`,
+		},
+		{
+			name: "with metadata",
+			req: &http.Request{
+				ProtoMajor: 2,
+				Method:     "POST",
+				Header: http.Header{
+					"Content-Type": []string{"application/grpc"},
+					"meta-foo":     {"foo-val"},
+					"meta-bar":     {"bar-val1", "bar-val2"},
+					"user-agent":   {"x/y a/b"},
+				},
+				URL: &url.URL{
+					Path: "/service/foo.bar",
+				},
+				RequestURI: "/service/foo.bar",
+			},
+			check: func(ht *serverHandlerTransport, tt *testCase) error {
+				want := metadata.MD{
+					"meta-bar":     {"bar-val1", "bar-val2"},
+					"user-agent":   {"x/y a/b"},
+					"meta-foo":     {"foo-val"},
+					"content-type": {"application/grpc"},
+				}
+
+				if !reflect.DeepEqual(ht.headerMD, want) {
+					return fmt.Errorf("metdata = %#v; want %#v", ht.headerMD, want)
+				}
+				return nil
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		rw := newTestHandlerResponseWriter()
+		if tt.modrw != nil {
+			rw = tt.modrw(rw)
+		}
+		got, gotErr := NewServerHandlerTransport(rw, tt.req, nil)
+		if (gotErr != nil) != (tt.wantErr != "") || (gotErr != nil && gotErr.Error() != tt.wantErr) {
+			t.Errorf("%s: error = %v; want %q", tt.name, gotErr, tt.wantErr)
+			continue
+		}
+		if gotErr != nil {
+			continue
+		}
+		if tt.check != nil {
+			if err := tt.check(got.(*serverHandlerTransport), &tt); err != nil {
+				t.Errorf("%s: %v", tt.name, err)
+			}
+		}
+	}
+}
+
+type testHandlerResponseWriter struct {
+	*httptest.ResponseRecorder
+	closeNotify chan bool
+}
+
+func (w testHandlerResponseWriter) CloseNotify() <-chan bool { return w.closeNotify }
+func (w testHandlerResponseWriter) Flush()                   {}
+
+func newTestHandlerResponseWriter() http.ResponseWriter {
+	return testHandlerResponseWriter{
+		ResponseRecorder: httptest.NewRecorder(),
+		closeNotify:      make(chan bool, 1),
+	}
+}
+
+type handleStreamTest struct {
+	t     *testing.T
+	bodyw *io.PipeWriter
+	req   *http.Request
+	rw    testHandlerResponseWriter
+	ht    *serverHandlerTransport
+}
+
+func newHandleStreamTest(t *testing.T) *handleStreamTest {
+	bodyr, bodyw := io.Pipe()
+	req := &http.Request{
+		ProtoMajor: 2,
+		Method:     "POST",
+		Header: http.Header{
+			"Content-Type": {"application/grpc"},
+		},
+		URL: &url.URL{
+			Path: "/service/foo.bar",
+		},
+		RequestURI: "/service/foo.bar",
+		Body:       bodyr,
+	}
+	rw := newTestHandlerResponseWriter().(testHandlerResponseWriter)
+	ht, err := NewServerHandlerTransport(rw, req, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return &handleStreamTest{
+		t:     t,
+		bodyw: bodyw,
+		ht:    ht.(*serverHandlerTransport),
+		rw:    rw,
+	}
+}
+
+func TestHandlerTransport_HandleStreams(t *testing.T) {
+	st := newHandleStreamTest(t)
+	handleStream := func(s *Stream) {
+		if want := "/service/foo.bar"; s.method != want {
+			t.Errorf("stream method = %q; want %q", s.method, want)
+		}
+		st.bodyw.Close() // no body
+		st.ht.WriteStatus(s, status.New(codes.OK, ""))
+	}
+	st.ht.HandleStreams(
+		func(s *Stream) { go handleStream(s) },
+		func(ctx context.Context, method string) context.Context { return ctx },
+	)
+	wantHeader := http.Header{
+		"Date":         nil,
+		"Content-Type": {"application/grpc"},
+		"Trailer":      {"Grpc-Status", "Grpc-Message", "Grpc-Status-Details-Bin"},
+		"Grpc-Status":  {"0"},
+	}
+	if !reflect.DeepEqual(st.rw.HeaderMap, wantHeader) {
+		t.Errorf("Header+Trailer Map: %#v; want %#v", st.rw.HeaderMap, wantHeader)
+	}
+}
+
+// Tests that codes.Unimplemented will close the body, per comment in handler_server.go.
+func TestHandlerTransport_HandleStreams_Unimplemented(t *testing.T) {
+	handleStreamCloseBodyTest(t, codes.Unimplemented, "thingy is unimplemented")
+}
+
+// Tests that codes.InvalidArgument will close the body, per comment in handler_server.go.
+func TestHandlerTransport_HandleStreams_InvalidArgument(t *testing.T) {
+	handleStreamCloseBodyTest(t, codes.InvalidArgument, "bad arg")
+}
+
+func handleStreamCloseBodyTest(t *testing.T, statusCode codes.Code, msg string) {
+	st := newHandleStreamTest(t)
+
+	handleStream := func(s *Stream) {
+		st.ht.WriteStatus(s, status.New(statusCode, msg))
+	}
+	st.ht.HandleStreams(
+		func(s *Stream) { go handleStream(s) },
+		func(ctx context.Context, method string) context.Context { return ctx },
+	)
+	wantHeader := http.Header{
+		"Date":         nil,
+		"Content-Type": {"application/grpc"},
+		"Trailer":      {"Grpc-Status", "Grpc-Message", "Grpc-Status-Details-Bin"},
+		"Grpc-Status":  {fmt.Sprint(uint32(statusCode))},
+		"Grpc-Message": {encodeGrpcMessage(msg)},
+	}
+
+	if !reflect.DeepEqual(st.rw.HeaderMap, wantHeader) {
+		t.Errorf("Header+Trailer mismatch.\n got: %#v\nwant: %#v", st.rw.HeaderMap, wantHeader)
+	}
+}
+
+func TestHandlerTransport_HandleStreams_Timeout(t *testing.T) {
+	bodyr, bodyw := io.Pipe()
+	req := &http.Request{
+		ProtoMajor: 2,
+		Method:     "POST",
+		Header: http.Header{
+			"Content-Type": {"application/grpc"},
+			"Grpc-Timeout": {"200m"},
+		},
+		URL: &url.URL{
+			Path: "/service/foo.bar",
+		},
+		RequestURI: "/service/foo.bar",
+		Body:       bodyr,
+	}
+	rw := newTestHandlerResponseWriter().(testHandlerResponseWriter)
+	ht, err := NewServerHandlerTransport(rw, req, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	runStream := func(s *Stream) {
+		defer bodyw.Close()
+		select {
+		case <-s.ctx.Done():
+		case <-time.After(5 * time.Second):
+			t.Errorf("timeout waiting for ctx.Done")
+			return
+		}
+		err := s.ctx.Err()
+		if err != context.DeadlineExceeded {
+			t.Errorf("ctx.Err = %v; want %v", err, context.DeadlineExceeded)
+			return
+		}
+		ht.WriteStatus(s, status.New(codes.DeadlineExceeded, "too slow"))
+	}
+	ht.HandleStreams(
+		func(s *Stream) { go runStream(s) },
+		func(ctx context.Context, method string) context.Context { return ctx },
+	)
+	wantHeader := http.Header{
+		"Date":         nil,
+		"Content-Type": {"application/grpc"},
+		"Trailer":      {"Grpc-Status", "Grpc-Message", "Grpc-Status-Details-Bin"},
+		"Grpc-Status":  {"4"},
+		"Grpc-Message": {encodeGrpcMessage("too slow")},
+	}
+	if !reflect.DeepEqual(rw.HeaderMap, wantHeader) {
+		t.Errorf("Header+Trailer Map mismatch.\n got: %#v\nwant: %#v", rw.HeaderMap, wantHeader)
+	}
+}
+
+// TestHandlerTransport_HandleStreams_MultiWriteStatus ensures that
+// concurrent "WriteStatus"s do not panic writing to closed "writes" channel.
+func TestHandlerTransport_HandleStreams_MultiWriteStatus(t *testing.T) {
+	testHandlerTransportHandleStreams(t, func(st *handleStreamTest, s *Stream) {
+		if want := "/service/foo.bar"; s.method != want {
+			t.Errorf("stream method = %q; want %q", s.method, want)
+		}
+		st.bodyw.Close() // no body
+
+		var wg sync.WaitGroup
+		wg.Add(5)
+		for i := 0; i < 5; i++ {
+			go func() {
+				defer wg.Done()
+				st.ht.WriteStatus(s, status.New(codes.OK, ""))
+			}()
+		}
+		wg.Wait()
+	})
+}
+
+// TestHandlerTransport_HandleStreams_WriteStatusWrite ensures that "Write"
+// following "WriteStatus" does not panic writing to closed "writes" channel.
+func TestHandlerTransport_HandleStreams_WriteStatusWrite(t *testing.T) {
+	testHandlerTransportHandleStreams(t, func(st *handleStreamTest, s *Stream) {
+		if want := "/service/foo.bar"; s.method != want {
+			t.Errorf("stream method = %q; want %q", s.method, want)
+		}
+		st.bodyw.Close() // no body
+
+		st.ht.WriteStatus(s, status.New(codes.OK, ""))
+		st.ht.Write(s, []byte("hdr"), []byte("data"), &Options{})
+	})
+}
+
+func testHandlerTransportHandleStreams(t *testing.T, handleStream func(st *handleStreamTest, s *Stream)) {
+	st := newHandleStreamTest(t)
+	st.ht.HandleStreams(
+		func(s *Stream) { go handleStream(st, s) },
+		func(ctx context.Context, method string) context.Context { return ctx },
+	)
+}
+
+func TestHandlerTransport_HandleStreams_ErrDetails(t *testing.T) {
+	errDetails := []proto.Message{
+		&epb.RetryInfo{
+			RetryDelay: &dpb.Duration{Seconds: 60},
+		},
+		&epb.ResourceInfo{
+			ResourceType: "foo bar",
+			ResourceName: "service.foo.bar",
+			Owner:        "User",
+		},
+	}
+
+	statusCode := codes.ResourceExhausted
+	msg := "you are being throttled"
+	st, err := status.New(statusCode, msg).WithDetails(errDetails...)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	stBytes, err := proto.Marshal(st.Proto())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	hst := newHandleStreamTest(t)
+	handleStream := func(s *Stream) {
+		hst.ht.WriteStatus(s, st)
+	}
+	hst.ht.HandleStreams(
+		func(s *Stream) { go handleStream(s) },
+		func(ctx context.Context, method string) context.Context { return ctx },
+	)
+	wantHeader := http.Header{
+		"Date":                    nil,
+		"Content-Type":            {"application/grpc"},
+		"Trailer":                 {"Grpc-Status", "Grpc-Message", "Grpc-Status-Details-Bin"},
+		"Grpc-Status":             {fmt.Sprint(uint32(statusCode))},
+		"Grpc-Message":            {encodeGrpcMessage(msg)},
+		"Grpc-Status-Details-Bin": {encodeBinHeader(stBytes)},
+	}
+
+	if !reflect.DeepEqual(hst.rw.HeaderMap, wantHeader) {
+		t.Errorf("Header+Trailer mismatch.\n got: %#v\nwant: %#v", hst.rw.HeaderMap, wantHeader)
+	}
+}

vendor/google.golang.org/grpc/transport/http_util.go

@@ -0,0 +1,530 @@
+/*
+ *
+ * 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 (
+	"bufio"
+	"bytes"
+	"encoding/base64"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/golang/protobuf/proto"
+	"golang.org/x/net/http2"
+	"golang.org/x/net/http2/hpack"
+	spb "google.golang.org/genproto/googleapis/rpc/status"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+const (
+	// http2MaxFrameLen specifies the max length of a HTTP2 frame.
+	http2MaxFrameLen = 16384 // 16KB frame
+	// http://http2.github.io/http2-spec/#SettingValues
+	http2InitHeaderTableSize = 4096
+	// http2IOBufSize specifies the buffer size for sending frames.
+	defaultWriteBufSize = 32 * 1024
+	defaultReadBufSize  = 32 * 1024
+	// baseContentType is the base content-type for gRPC.  This is a valid
+	// content-type on it's own, but can also include a content-subtype such as
+	// "proto" as a suffix after "+" or ";".  See
+	// https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md#requests
+	// for more details.
+	baseContentType = "application/grpc"
+)
+
+var (
+	clientPreface   = []byte(http2.ClientPreface)
+	http2ErrConvTab = map[http2.ErrCode]codes.Code{
+		http2.ErrCodeNo:                 codes.Internal,
+		http2.ErrCodeProtocol:           codes.Internal,
+		http2.ErrCodeInternal:           codes.Internal,
+		http2.ErrCodeFlowControl:        codes.ResourceExhausted,
+		http2.ErrCodeSettingsTimeout:    codes.Internal,
+		http2.ErrCodeStreamClosed:       codes.Internal,
+		http2.ErrCodeFrameSize:          codes.Internal,
+		http2.ErrCodeRefusedStream:      codes.Unavailable,
+		http2.ErrCodeCancel:             codes.Canceled,
+		http2.ErrCodeCompression:        codes.Internal,
+		http2.ErrCodeConnect:            codes.Internal,
+		http2.ErrCodeEnhanceYourCalm:    codes.ResourceExhausted,
+		http2.ErrCodeInadequateSecurity: codes.PermissionDenied,
+		http2.ErrCodeHTTP11Required:     codes.FailedPrecondition,
+	}
+	statusCodeConvTab = map[codes.Code]http2.ErrCode{
+		codes.Internal:          http2.ErrCodeInternal,
+		codes.Canceled:          http2.ErrCodeCancel,
+		codes.Unavailable:       http2.ErrCodeRefusedStream,
+		codes.ResourceExhausted: http2.ErrCodeEnhanceYourCalm,
+		codes.PermissionDenied:  http2.ErrCodeInadequateSecurity,
+	}
+	httpStatusConvTab = map[int]codes.Code{
+		// 400 Bad Request - INTERNAL.
+		http.StatusBadRequest: codes.Internal,
+		// 401 Unauthorized  - UNAUTHENTICATED.
+		http.StatusUnauthorized: codes.Unauthenticated,
+		// 403 Forbidden - PERMISSION_DENIED.
+		http.StatusForbidden: codes.PermissionDenied,
+		// 404 Not Found - UNIMPLEMENTED.
+		http.StatusNotFound: codes.Unimplemented,
+		// 429 Too Many Requests - UNAVAILABLE.
+		http.StatusTooManyRequests: codes.Unavailable,
+		// 502 Bad Gateway - UNAVAILABLE.
+		http.StatusBadGateway: codes.Unavailable,
+		// 503 Service Unavailable - UNAVAILABLE.
+		http.StatusServiceUnavailable: codes.Unavailable,
+		// 504 Gateway timeout - UNAVAILABLE.
+		http.StatusGatewayTimeout: codes.Unavailable,
+	}
+)
+
+// Records the states during HPACK decoding. Must be reset once the
+// decoding of the entire headers are finished.
+type decodeState struct {
+	encoding string
+	// statusGen caches the stream status received from the trailer the server
+	// sent.  Client side only.  Do not access directly.  After all trailers are
+	// parsed, use the status method to retrieve the status.
+	statusGen *status.Status
+	// rawStatusCode and rawStatusMsg are set from the raw trailer fields and are not
+	// intended for direct access outside of parsing.
+	rawStatusCode *int
+	rawStatusMsg  string
+	httpStatus    *int
+	// Server side only fields.
+	timeoutSet bool
+	timeout    time.Duration
+	method     string
+	// key-value metadata map from the peer.
+	mdata          map[string][]string
+	statsTags      []byte
+	statsTrace     []byte
+	contentSubtype string
+}
+
+// isReservedHeader checks whether hdr belongs to HTTP2 headers
+// reserved by gRPC protocol. Any other headers are classified as the
+// user-specified metadata.
+func isReservedHeader(hdr string) bool {
+	if hdr != "" && hdr[0] == ':' {
+		return true
+	}
+	switch hdr {
+	case "content-type",
+		"grpc-message-type",
+		"grpc-encoding",
+		"grpc-message",
+		"grpc-status",
+		"grpc-timeout",
+		"grpc-status-details-bin",
+		"te":
+		return true
+	default:
+		return false
+	}
+}
+
+// isWhitelistedPseudoHeader checks whether hdr belongs to HTTP2 pseudoheaders
+// that should be propagated into metadata visible to users.
+func isWhitelistedPseudoHeader(hdr string) bool {
+	switch hdr {
+	case ":authority":
+		return true
+	default:
+		return false
+	}
+}
+
+// contentSubtype returns the content-subtype for the given content-type.  The
+// given content-type must be a valid content-type that starts with
+// "application/grpc". A content-subtype will follow "application/grpc" after a
+// "+" or ";". See
+// https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md#requests for
+// more details.
+//
+// If contentType is not a valid content-type for gRPC, the boolean
+// will be false, otherwise true. If content-type == "application/grpc",
+// "application/grpc+", or "application/grpc;", the boolean will be true,
+// but no content-subtype will be returned.
+//
+// contentType is assumed to be lowercase already.
+func contentSubtype(contentType string) (string, bool) {
+	if contentType == baseContentType {
+		return "", true
+	}
+	if !strings.HasPrefix(contentType, baseContentType) {
+		return "", false
+	}
+	// guaranteed since != baseContentType and has baseContentType prefix
+	switch contentType[len(baseContentType)] {
+	case '+', ';':
+		// this will return true for "application/grpc+" or "application/grpc;"
+		// which the previous validContentType function tested to be valid, so we
+		// just say that no content-subtype is specified in this case
+		return contentType[len(baseContentType)+1:], true
+	default:
+		return "", false
+	}
+}
+
+// contentSubtype is assumed to be lowercase
+func contentType(contentSubtype string) string {
+	if contentSubtype == "" {
+		return baseContentType
+	}
+	return baseContentType + "+" + contentSubtype
+}
+
+func (d *decodeState) status() *status.Status {
+	if d.statusGen == nil {
+		// No status-details were provided; generate status using code/msg.
+		d.statusGen = status.New(codes.Code(int32(*(d.rawStatusCode))), d.rawStatusMsg)
+	}
+	return d.statusGen
+}
+
+const binHdrSuffix = "-bin"
+
+func encodeBinHeader(v []byte) string {
+	return base64.RawStdEncoding.EncodeToString(v)
+}
+
+func decodeBinHeader(v string) ([]byte, error) {
+	if len(v)%4 == 0 {
+		// Input was padded, or padding was not necessary.
+		return base64.StdEncoding.DecodeString(v)
+	}
+	return base64.RawStdEncoding.DecodeString(v)
+}
+
+func encodeMetadataHeader(k, v string) string {
+	if strings.HasSuffix(k, binHdrSuffix) {
+		return encodeBinHeader(([]byte)(v))
+	}
+	return v
+}
+
+func decodeMetadataHeader(k, v string) (string, error) {
+	if strings.HasSuffix(k, binHdrSuffix) {
+		b, err := decodeBinHeader(v)
+		return string(b), err
+	}
+	return v, nil
+}
+
+func (d *decodeState) decodeResponseHeader(frame *http2.MetaHeadersFrame) error {
+	for _, hf := range frame.Fields {
+		if err := d.processHeaderField(hf); err != nil {
+			return err
+		}
+	}
+
+	// If grpc status exists, no need to check further.
+	if d.rawStatusCode != nil || d.statusGen != nil {
+		return nil
+	}
+
+	// If grpc status doesn't exist and http status doesn't exist,
+	// then it's a malformed header.
+	if d.httpStatus == nil {
+		return streamErrorf(codes.Internal, "malformed header: doesn't contain status(gRPC or HTTP)")
+	}
+
+	if *(d.httpStatus) != http.StatusOK {
+		code, ok := httpStatusConvTab[*(d.httpStatus)]
+		if !ok {
+			code = codes.Unknown
+		}
+		return streamErrorf(code, http.StatusText(*(d.httpStatus)))
+	}
+
+	// gRPC status doesn't exist and http status is OK.
+	// Set rawStatusCode to be unknown and return nil error.
+	// So that, if the stream has ended this Unknown status
+	// will be propogated to the user.
+	// Otherwise, it will be ignored. In which case, status from
+	// a later trailer, that has StreamEnded flag set, is propogated.
+	code := int(codes.Unknown)
+	d.rawStatusCode = &code
+	return nil
+
+}
+
+func (d *decodeState) addMetadata(k, v string) {
+	if d.mdata == nil {
+		d.mdata = make(map[string][]string)
+	}
+	d.mdata[k] = append(d.mdata[k], v)
+}
+
+func (d *decodeState) processHeaderField(f hpack.HeaderField) error {
+	switch f.Name {
+	case "content-type":
+		contentSubtype, validContentType := contentSubtype(f.Value)
+		if !validContentType {
+			return streamErrorf(codes.FailedPrecondition, "transport: received the unexpected content-type %q", f.Value)
+		}
+		d.contentSubtype = contentSubtype
+		// TODO: do we want to propagate the whole content-type in the metadata,
+		// or come up with a way to just propagate the content-subtype if it was set?
+		// ie {"content-type": "application/grpc+proto"} or {"content-subtype": "proto"}
+		// in the metadata?
+		d.addMetadata(f.Name, f.Value)
+	case "grpc-encoding":
+		d.encoding = f.Value
+	case "grpc-status":
+		code, err := strconv.Atoi(f.Value)
+		if err != nil {
+			return streamErrorf(codes.Internal, "transport: malformed grpc-status: %v", err)
+		}
+		d.rawStatusCode = &code
+	case "grpc-message":
+		d.rawStatusMsg = decodeGrpcMessage(f.Value)
+	case "grpc-status-details-bin":
+		v, err := decodeBinHeader(f.Value)
+		if err != nil {
+			return streamErrorf(codes.Internal, "transport: malformed grpc-status-details-bin: %v", err)
+		}
+		s := &spb.Status{}
+		if err := proto.Unmarshal(v, s); err != nil {
+			return streamErrorf(codes.Internal, "transport: malformed grpc-status-details-bin: %v", err)
+		}
+		d.statusGen = status.FromProto(s)
+	case "grpc-timeout":
+		d.timeoutSet = true
+		var err error
+		if d.timeout, err = decodeTimeout(f.Value); err != nil {
+			return streamErrorf(codes.Internal, "transport: malformed time-out: %v", err)
+		}
+	case ":path":
+		d.method = f.Value
+	case ":status":
+		code, err := strconv.Atoi(f.Value)
+		if err != nil {
+			return streamErrorf(codes.Internal, "transport: malformed http-status: %v", err)
+		}
+		d.httpStatus = &code
+	case "grpc-tags-bin":
+		v, err := decodeBinHeader(f.Value)
+		if err != nil {
+			return streamErrorf(codes.Internal, "transport: malformed grpc-tags-bin: %v", err)
+		}
+		d.statsTags = v
+		d.addMetadata(f.Name, string(v))
+	case "grpc-trace-bin":
+		v, err := decodeBinHeader(f.Value)
+		if err != nil {
+			return streamErrorf(codes.Internal, "transport: malformed grpc-trace-bin: %v", err)
+		}
+		d.statsTrace = v
+		d.addMetadata(f.Name, string(v))
+	default:
+		if isReservedHeader(f.Name) && !isWhitelistedPseudoHeader(f.Name) {
+			break
+		}
+		v, err := decodeMetadataHeader(f.Name, f.Value)
+		if err != nil {
+			errorf("Failed to decode metadata header (%q, %q): %v", f.Name, f.Value, err)
+			return nil
+		}
+		d.addMetadata(f.Name, string(v))
+	}
+	return nil
+}
+
+type timeoutUnit uint8
+
+const (
+	hour        timeoutUnit = 'H'
+	minute      timeoutUnit = 'M'
+	second      timeoutUnit = 'S'
+	millisecond timeoutUnit = 'm'
+	microsecond timeoutUnit = 'u'
+	nanosecond  timeoutUnit = 'n'
+)
+
+func timeoutUnitToDuration(u timeoutUnit) (d time.Duration, ok bool) {
+	switch u {
+	case hour:
+		return time.Hour, true
+	case minute:
+		return time.Minute, true
+	case second:
+		return time.Second, true
+	case millisecond:
+		return time.Millisecond, true
+	case microsecond:
+		return time.Microsecond, true
+	case nanosecond:
+		return time.Nanosecond, true
+	default:
+	}
+	return
+}
+
+const maxTimeoutValue int64 = 100000000 - 1
+
+// div does integer division and round-up the result. Note that this is
+// equivalent to (d+r-1)/r but has less chance to overflow.
+func div(d, r time.Duration) int64 {
+	if m := d % r; m > 0 {
+		return int64(d/r + 1)
+	}
+	return int64(d / r)
+}
+
+// TODO(zhaoq): It is the simplistic and not bandwidth efficient. Improve it.
+func encodeTimeout(t time.Duration) string {
+	if t <= 0 {
+		return "0n"
+	}
+	if d := div(t, time.Nanosecond); d <= maxTimeoutValue {
+		return strconv.FormatInt(d, 10) + "n"
+	}
+	if d := div(t, time.Microsecond); d <= maxTimeoutValue {
+		return strconv.FormatInt(d, 10) + "u"
+	}
+	if d := div(t, time.Millisecond); d <= maxTimeoutValue {
+		return strconv.FormatInt(d, 10) + "m"
+	}
+	if d := div(t, time.Second); d <= maxTimeoutValue {
+		return strconv.FormatInt(d, 10) + "S"
+	}
+	if d := div(t, time.Minute); d <= maxTimeoutValue {
+		return strconv.FormatInt(d, 10) + "M"
+	}
+	// Note that maxTimeoutValue * time.Hour > MaxInt64.
+	return strconv.FormatInt(div(t, time.Hour), 10) + "H"
+}
+
+func decodeTimeout(s string) (time.Duration, error) {
+	size := len(s)
+	if size < 2 {
+		return 0, fmt.Errorf("transport: timeout string is too short: %q", s)
+	}
+	unit := timeoutUnit(s[size-1])
+	d, ok := timeoutUnitToDuration(unit)
+	if !ok {
+		return 0, fmt.Errorf("transport: timeout unit is not recognized: %q", s)
+	}
+	t, err := strconv.ParseInt(s[:size-1], 10, 64)
+	if err != nil {
+		return 0, err
+	}
+	return d * time.Duration(t), nil
+}
+
+const (
+	spaceByte   = ' '
+	tildaByte   = '~'
+	percentByte = '%'
+)
+
+// encodeGrpcMessage is used to encode status code in header field
+// "grpc-message".
+// It checks to see if each individual byte in msg is an
+// allowable byte, and then either percent encoding or passing it through.
+// When percent encoding, the byte is converted into hexadecimal notation
+// with a '%' prepended.
+func encodeGrpcMessage(msg string) string {
+	if msg == "" {
+		return ""
+	}
+	lenMsg := len(msg)
+	for i := 0; i < lenMsg; i++ {
+		c := msg[i]
+		if !(c >= spaceByte && c < tildaByte && c != percentByte) {
+			return encodeGrpcMessageUnchecked(msg)
+		}
+	}
+	return msg
+}
+
+func encodeGrpcMessageUnchecked(msg string) string {
+	var buf bytes.Buffer
+	lenMsg := len(msg)
+	for i := 0; i < lenMsg; i++ {
+		c := msg[i]
+		if c >= spaceByte && c < tildaByte && c != percentByte {
+			buf.WriteByte(c)
+		} else {
+			buf.WriteString(fmt.Sprintf("%%%02X", c))
+		}
+	}
+	return buf.String()
+}
+
+// decodeGrpcMessage decodes the msg encoded by encodeGrpcMessage.
+func decodeGrpcMessage(msg string) string {
+	if msg == "" {
+		return ""
+	}
+	lenMsg := len(msg)
+	for i := 0; i < lenMsg; i++ {
+		if msg[i] == percentByte && i+2 < lenMsg {
+			return decodeGrpcMessageUnchecked(msg)
+		}
+	}
+	return msg
+}
+
+func decodeGrpcMessageUnchecked(msg string) string {
+	var buf bytes.Buffer
+	lenMsg := len(msg)
+	for i := 0; i < lenMsg; i++ {
+		c := msg[i]
+		if c == percentByte && i+2 < lenMsg {
+			parsed, err := strconv.ParseUint(msg[i+1:i+3], 16, 8)
+			if err != nil {
+				buf.WriteByte(c)
+			} else {
+				buf.WriteByte(byte(parsed))
+				i += 2
+			}
+		} else {
+			buf.WriteByte(c)
+		}
+	}
+	return buf.String()
+}
+
+type framer struct {
+	numWriters int32
+	reader     io.Reader
+	writer     *bufio.Writer
+	fr         *http2.Framer
+}
+
+func newFramer(conn net.Conn, writeBufferSize, readBufferSize int) *framer {
+	f := &framer{
+		reader: bufio.NewReaderSize(conn, readBufferSize),
+		writer: bufio.NewWriterSize(conn, writeBufferSize),
+	}
+	f.fr = http2.NewFramer(f.writer, f.reader)
+	// Opt-in to Frame reuse API on framer to reduce garbage.
+	// Frames aren't safe to read from after a subsequent call to ReadFrame.
+	f.fr.SetReuseFrames()
+	f.fr.ReadMetaHeaders = hpack.NewDecoder(http2InitHeaderTableSize, nil)
+	return f
+}

vendor/google.golang.org/grpc/transport/http_util_test.go

@@ -0,0 +1,176 @@
+/*
+ *
+ * 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 (
+	"fmt"
+	"reflect"
+	"testing"
+	"time"
+)
+
+func TestTimeoutEncode(t *testing.T) {
+	for _, test := range []struct {
+		in  string
+		out string
+	}{
+		{"12345678ns", "12345678n"},
+		{"123456789ns", "123457u"},
+		{"12345678us", "12345678u"},
+		{"123456789us", "123457m"},
+		{"12345678ms", "12345678m"},
+		{"123456789ms", "123457S"},
+		{"12345678s", "12345678S"},
+		{"123456789s", "2057614M"},
+		{"12345678m", "12345678M"},
+		{"123456789m", "2057614H"},
+	} {
+		d, err := time.ParseDuration(test.in)
+		if err != nil {
+			t.Fatalf("failed to parse duration string %s: %v", test.in, err)
+		}
+		out := encodeTimeout(d)
+		if out != test.out {
+			t.Fatalf("timeoutEncode(%s) = %s, want %s", test.in, out, test.out)
+		}
+	}
+}
+
+func TestTimeoutDecode(t *testing.T) {
+	for _, test := range []struct {
+		// input
+		s string
+		// output
+		d   time.Duration
+		err error
+	}{
+		{"1234S", time.Second * 1234, nil},
+		{"1234x", 0, fmt.Errorf("transport: timeout unit is not recognized: %q", "1234x")},
+		{"1", 0, fmt.Errorf("transport: timeout string is too short: %q", "1")},
+		{"", 0, fmt.Errorf("transport: timeout string is too short: %q", "")},
+	} {
+		d, err := decodeTimeout(test.s)
+		if d != test.d || fmt.Sprint(err) != fmt.Sprint(test.err) {
+			t.Fatalf("timeoutDecode(%q) = %d, %v, want %d, %v", test.s, int64(d), err, int64(test.d), test.err)
+		}
+	}
+}
+
+func TestContentSubtype(t *testing.T) {
+	tests := []struct {
+		contentType string
+		want        string
+		wantValid   bool
+	}{
+		{"application/grpc", "", true},
+		{"application/grpc+", "", true},
+		{"application/grpc+blah", "blah", true},
+		{"application/grpc;", "", true},
+		{"application/grpc;blah", "blah", true},
+		{"application/grpcd", "", false},
+		{"application/grpd", "", false},
+		{"application/grp", "", false},
+	}
+	for _, tt := range tests {
+		got, gotValid := contentSubtype(tt.contentType)
+		if got != tt.want || gotValid != tt.wantValid {
+			t.Errorf("contentSubtype(%q) = (%v, %v); want (%v, %v)", tt.contentType, got, gotValid, tt.want, tt.wantValid)
+		}
+	}
+}
+
+func TestEncodeGrpcMessage(t *testing.T) {
+	for _, tt := range []struct {
+		input    string
+		expected string
+	}{
+		{"", ""},
+		{"Hello", "Hello"},
+		{"my favorite character is \u0000", "my favorite character is %00"},
+		{"my favorite character is %", "my favorite character is %25"},
+	} {
+		actual := encodeGrpcMessage(tt.input)
+		if tt.expected != actual {
+			t.Errorf("encodeGrpcMessage(%v) = %v, want %v", tt.input, actual, tt.expected)
+		}
+	}
+}
+
+func TestDecodeGrpcMessage(t *testing.T) {
+	for _, tt := range []struct {
+		input    string
+		expected string
+	}{
+		{"", ""},
+		{"Hello", "Hello"},
+		{"H%61o", "Hao"},
+		{"H%6", "H%6"},
+		{"%G0", "%G0"},
+		{"%E7%B3%BB%E7%BB%9F", "系统"},
+	} {
+		actual := decodeGrpcMessage(tt.input)
+		if tt.expected != actual {
+			t.Errorf("dncodeGrpcMessage(%v) = %v, want %v", tt.input, actual, tt.expected)
+		}
+	}
+}
+
+const binaryValue = string(128)
+
+func TestEncodeMetadataHeader(t *testing.T) {
+	for _, test := range []struct {
+		// input
+		kin string
+		vin string
+		// output
+		vout string
+	}{
+		{"key", "abc", "abc"},
+		{"KEY", "abc", "abc"},
+		{"key-bin", "abc", "YWJj"},
+		{"key-bin", binaryValue, "woA"},
+	} {
+		v := encodeMetadataHeader(test.kin, test.vin)
+		if !reflect.DeepEqual(v, test.vout) {
+			t.Fatalf("encodeMetadataHeader(%q, %q) = %q, want %q", test.kin, test.vin, v, test.vout)
+		}
+	}
+}
+
+func TestDecodeMetadataHeader(t *testing.T) {
+	for _, test := range []struct {
+		// input
+		kin string
+		vin string
+		// output
+		vout string
+		err  error
+	}{
+		{"a", "abc", "abc", nil},
+		{"key-bin", "Zm9vAGJhcg==", "foo\x00bar", nil},
+		{"key-bin", "Zm9vAGJhcg", "foo\x00bar", nil},
+		{"key-bin", "woA=", binaryValue, nil},
+		{"a", "abc,efg", "abc,efg", nil},
+	} {
+		v, err := decodeMetadataHeader(test.kin, test.vin)
+		if !reflect.DeepEqual(v, test.vout) || !reflect.DeepEqual(err, test.err) {
+			t.Fatalf("decodeMetadataHeader(%q, %q) = %q, %v, want %q, %v", test.kin, test.vin, v, err, test.vout, test.err)
+		}
+	}
+}

vendor/google.golang.org/grpc/transport/log.go

@@ -0,0 +1,50 @@
+/*
+ *
+ * Copyright 2017 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.
+ *
+ */
+
+// This file contains wrappers for grpclog functions.
+// The transport package only logs to verbose level 2 by default.
+
+package transport
+
+import "google.golang.org/grpc/grpclog"
+
+const logLevel = 2
+
+func infof(format string, args ...interface{}) {
+	if grpclog.V(logLevel) {
+		grpclog.Infof(format, args...)
+	}
+}
+
+func warningf(format string, args ...interface{}) {
+	if grpclog.V(logLevel) {
+		grpclog.Warningf(format, args...)
+	}
+}
+
+func errorf(format string, args ...interface{}) {
+	if grpclog.V(logLevel) {
+		grpclog.Errorf(format, args...)
+	}
+}
+
+func fatalf(format string, args ...interface{}) {
+	if grpclog.V(logLevel) {
+		grpclog.Fatalf(format, args...)
+	}
+}

vendor/google.golang.org/grpc/transport/transport.go

@@ -0,0 +1,778 @@
+/*
+ *
+ * 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 defines and implements message oriented communication
+// channel to complete various transactions (e.g., an RPC).  It is meant for
+// grpc-internal usage and is not intended to be imported directly by users.
+package transport // import "google.golang.org/grpc/transport"
+
+import (
+	"fmt"
+	"io"
+	"net"
+	"sync"
+
+	"golang.org/x/net/context"
+	"golang.org/x/net/http2"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/keepalive"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/stats"
+	"google.golang.org/grpc/status"
+	"google.golang.org/grpc/tap"
+)
+
+// recvMsg represents the received msg from the transport. All transport
+// protocol specific info has been removed.
+type recvMsg struct {
+	data []byte
+	// nil: received some data
+	// io.EOF: stream is completed. data is nil.
+	// other non-nil error: transport failure. data is nil.
+	err error
+}
+
+// recvBuffer is an unbounded channel of recvMsg structs.
+// Note recvBuffer differs from controlBuffer only in that recvBuffer
+// holds a channel of only recvMsg structs instead of objects implementing "item" interface.
+// recvBuffer is written to much more often than
+// controlBuffer and using strict recvMsg structs helps avoid allocation in "recvBuffer.put"
+type recvBuffer struct {
+	c       chan recvMsg
+	mu      sync.Mutex
+	backlog []recvMsg
+}
+
+func newRecvBuffer() *recvBuffer {
+	b := &recvBuffer{
+		c: make(chan recvMsg, 1),
+	}
+	return b
+}
+
+func (b *recvBuffer) put(r recvMsg) {
+	b.mu.Lock()
+	if len(b.backlog) == 0 {
+		select {
+		case b.c <- r:
+			b.mu.Unlock()
+			return
+		default:
+		}
+	}
+	b.backlog = append(b.backlog, r)
+	b.mu.Unlock()
+}
+
+func (b *recvBuffer) load() {
+	b.mu.Lock()
+	if len(b.backlog) > 0 {
+		select {
+		case b.c <- b.backlog[0]:
+			b.backlog[0] = recvMsg{}
+			b.backlog = b.backlog[1:]
+		default:
+		}
+	}
+	b.mu.Unlock()
+}
+
+// get returns the channel that receives a recvMsg in the buffer.
+//
+// Upon receipt of a recvMsg, the caller should call load to send another
+// recvMsg onto the channel if there is any.
+func (b *recvBuffer) get() <-chan recvMsg {
+	return b.c
+}
+
+// recvBufferReader implements io.Reader interface to read the data from
+// recvBuffer.
+type recvBufferReader struct {
+	ctx    context.Context
+	goAway chan struct{}
+	recv   *recvBuffer
+	last   []byte // Stores the remaining data in the previous calls.
+	err    error
+}
+
+// Read reads the next len(p) bytes from last. If last is drained, it tries to
+// read additional data from recv. It blocks if there no additional data available
+// in recv. If Read returns any non-nil error, it will continue to return that error.
+func (r *recvBufferReader) Read(p []byte) (n int, err error) {
+	if r.err != nil {
+		return 0, r.err
+	}
+	n, r.err = r.read(p)
+	return n, r.err
+}
+
+func (r *recvBufferReader) read(p []byte) (n int, err error) {
+	if r.last != nil && len(r.last) > 0 {
+		// Read remaining data left in last call.
+		copied := copy(p, r.last)
+		r.last = r.last[copied:]
+		return copied, nil
+	}
+	select {
+	case <-r.ctx.Done():
+		return 0, ContextErr(r.ctx.Err())
+	case <-r.goAway:
+		return 0, errStreamDrain
+	case m := <-r.recv.get():
+		r.recv.load()
+		if m.err != nil {
+			return 0, m.err
+		}
+		copied := copy(p, m.data)
+		r.last = m.data[copied:]
+		return copied, nil
+	}
+}
+
+// All items in an out of a controlBuffer should be the same type.
+type item interface {
+	item()
+}
+
+// controlBuffer is an unbounded channel of item.
+type controlBuffer struct {
+	c       chan item
+	mu      sync.Mutex
+	backlog []item
+}
+
+func newControlBuffer() *controlBuffer {
+	b := &controlBuffer{
+		c: make(chan item, 1),
+	}
+	return b
+}
+
+func (b *controlBuffer) put(r item) {
+	b.mu.Lock()
+	if len(b.backlog) == 0 {
+		select {
+		case b.c <- r:
+			b.mu.Unlock()
+			return
+		default:
+		}
+	}
+	b.backlog = append(b.backlog, r)
+	b.mu.Unlock()
+}
+
+func (b *controlBuffer) load() {
+	b.mu.Lock()
+	if len(b.backlog) > 0 {
+		select {
+		case b.c <- b.backlog[0]:
+			b.backlog[0] = nil
+			b.backlog = b.backlog[1:]
+		default:
+		}
+	}
+	b.mu.Unlock()
+}
+
+// get returns the channel that receives an item in the buffer.
+//
+// Upon receipt of an item, the caller should call load to send another
+// item onto the channel if there is any.
+func (b *controlBuffer) get() <-chan item {
+	return b.c
+}
+
+type streamState uint8
+
+const (
+	streamActive    streamState = iota
+	streamWriteDone             // EndStream sent
+	streamReadDone              // EndStream received
+	streamDone                  // the entire stream is finished.
+)
+
+// Stream represents an RPC in the transport layer.
+type Stream struct {
+	id           uint32
+	st           ServerTransport    // nil for client side Stream
+	ctx          context.Context    // the associated context of the stream
+	cancel       context.CancelFunc // always nil for client side Stream
+	done         chan struct{}      // closed when the final status arrives
+	goAway       chan struct{}      // closed when a GOAWAY control message is received
+	method       string             // the associated RPC method of the stream
+	recvCompress string
+	sendCompress string
+	buf          *recvBuffer
+	trReader     io.Reader
+	fc           *inFlow
+	recvQuota    uint32
+	waiters      waiters
+
+	// Callback to state application's intentions to read data. This
+	// is used to adjust flow control, if needed.
+	requestRead func(int)
+
+	sendQuotaPool *quotaPool
+	headerChan    chan struct{} // closed to indicate the end of header metadata.
+	headerDone    bool          // set when headerChan is closed. Used to avoid closing headerChan multiple times.
+	header        metadata.MD   // the received header metadata.
+	trailer       metadata.MD   // the key-value map of trailer metadata.
+
+	mu       sync.RWMutex // guard the following
+	headerOk bool         // becomes true from the first header is about to send
+	state    streamState
+
+	status *status.Status // the status error received from the server
+
+	rstStream bool          // indicates whether a RST_STREAM frame needs to be sent
+	rstError  http2.ErrCode // the error that needs to be sent along with the RST_STREAM frame
+
+	bytesReceived bool // indicates whether any bytes have been received on this stream
+	unprocessed   bool // set if the server sends a refused stream or GOAWAY including this stream
+
+	// contentSubtype is the content-subtype for requests.
+	// this must be lowercase or the behavior is undefined.
+	contentSubtype string
+}
+
+func (s *Stream) waitOnHeader() error {
+	if s.headerChan == nil {
+		// On the server headerChan is always nil since a stream originates
+		// only after having received headers.
+		return nil
+	}
+	wc := s.waiters
+	select {
+	case <-wc.ctx.Done():
+		return ContextErr(wc.ctx.Err())
+	case <-wc.goAway:
+		return errStreamDrain
+	case <-s.headerChan:
+		return nil
+	}
+}
+
+// RecvCompress returns the compression algorithm applied to the inbound
+// message. It is empty string if there is no compression applied.
+func (s *Stream) RecvCompress() string {
+	if err := s.waitOnHeader(); err != nil {
+		return ""
+	}
+	return s.recvCompress
+}
+
+// SetSendCompress sets the compression algorithm to the stream.
+func (s *Stream) SetSendCompress(str string) {
+	s.sendCompress = str
+}
+
+// Done returns a chanel which is closed when it receives the final status
+// from the server.
+func (s *Stream) Done() <-chan struct{} {
+	return s.done
+}
+
+// GoAway returns a channel which is closed when the server sent GoAways signal
+// before this stream was initiated.
+func (s *Stream) GoAway() <-chan struct{} {
+	return s.goAway
+}
+
+// Header acquires the key-value pairs of header metadata once it
+// is available. It blocks until i) the metadata is ready or ii) there is no
+// header metadata or iii) the stream is canceled/expired.
+func (s *Stream) Header() (metadata.MD, error) {
+	err := s.waitOnHeader()
+	// Even if the stream is closed, header is returned if available.
+	select {
+	case <-s.headerChan:
+		return s.header.Copy(), nil
+	default:
+	}
+	return nil, err
+}
+
+// Trailer returns the cached trailer metedata. Note that if it is not called
+// after the entire stream is done, it could return an empty MD. Client
+// side only.
+func (s *Stream) Trailer() metadata.MD {
+	s.mu.RLock()
+	c := s.trailer.Copy()
+	s.mu.RUnlock()
+	return c
+}
+
+// ServerTransport returns the underlying ServerTransport for the stream.
+// The client side stream always returns nil.
+func (s *Stream) ServerTransport() ServerTransport {
+	return s.st
+}
+
+// ContentSubtype returns the content-subtype for a request. For example, a
+// content-subtype of "proto" will result in a content-type of
+// "application/grpc+proto". This will always be lowercase.  See
+// https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md#requests for
+// more details.
+func (s *Stream) ContentSubtype() string {
+	return s.contentSubtype
+}
+
+// Context returns the context of the stream.
+func (s *Stream) Context() context.Context {
+	return s.ctx
+}
+
+// Method returns the method for the stream.
+func (s *Stream) Method() string {
+	return s.method
+}
+
+// Status returns the status received from the server.
+func (s *Stream) Status() *status.Status {
+	return s.status
+}
+
+// SetHeader sets the header metadata. This can be called multiple times.
+// Server side only.
+func (s *Stream) SetHeader(md metadata.MD) error {
+	s.mu.Lock()
+	if s.headerOk || s.state == streamDone {
+		s.mu.Unlock()
+		return ErrIllegalHeaderWrite
+	}
+	if md.Len() == 0 {
+		s.mu.Unlock()
+		return nil
+	}
+	s.header = metadata.Join(s.header, md)
+	s.mu.Unlock()
+	return nil
+}
+
+// SetTrailer sets the trailer metadata which will be sent with the RPC status
+// by the server. This can be called multiple times. Server side only.
+func (s *Stream) SetTrailer(md metadata.MD) error {
+	if md.Len() == 0 {
+		return nil
+	}
+	s.mu.Lock()
+	s.trailer = metadata.Join(s.trailer, md)
+	s.mu.Unlock()
+	return nil
+}
+
+func (s *Stream) write(m recvMsg) {
+	s.buf.put(m)
+}
+
+// Read reads all p bytes from the wire for this stream.
+func (s *Stream) Read(p []byte) (n int, err error) {
+	// Don't request a read if there was an error earlier
+	if er := s.trReader.(*transportReader).er; er != nil {
+		return 0, er
+	}
+	s.requestRead(len(p))
+	return io.ReadFull(s.trReader, p)
+}
+
+// tranportReader reads all the data available for this Stream from the transport and
+// passes them into the decoder, which converts them into a gRPC message stream.
+// The error is io.EOF when the stream is done or another non-nil error if
+// the stream broke.
+type transportReader struct {
+	reader io.Reader
+	// The handler to control the window update procedure for both this
+	// particular stream and the associated transport.
+	windowHandler func(int)
+	er            error
+}
+
+func (t *transportReader) Read(p []byte) (n int, err error) {
+	n, err = t.reader.Read(p)
+	if err != nil {
+		t.er = err
+		return
+	}
+	t.windowHandler(n)
+	return
+}
+
+// finish sets the stream's state and status, and closes the done channel.
+// s.mu must be held by the caller.  st must always be non-nil.
+func (s *Stream) finish(st *status.Status) {
+	s.status = st
+	s.state = streamDone
+	close(s.done)
+}
+
+// BytesReceived indicates whether any bytes have been received on this stream.
+func (s *Stream) BytesReceived() bool {
+	s.mu.Lock()
+	br := s.bytesReceived
+	s.mu.Unlock()
+	return br
+}
+
+// Unprocessed indicates whether the server did not process this stream --
+// i.e. it sent a refused stream or GOAWAY including this stream ID.
+func (s *Stream) Unprocessed() bool {
+	s.mu.Lock()
+	br := s.unprocessed
+	s.mu.Unlock()
+	return br
+}
+
+// GoString is implemented by Stream so context.String() won't
+// race when printing %#v.
+func (s *Stream) GoString() string {
+	return fmt.Sprintf("<stream: %p, %v>", s, s.method)
+}
+
+// The key to save transport.Stream in the context.
+type streamKey struct{}
+
+// newContextWithStream creates a new context from ctx and attaches stream
+// to it.
+func newContextWithStream(ctx context.Context, stream *Stream) context.Context {
+	return context.WithValue(ctx, streamKey{}, stream)
+}
+
+// StreamFromContext returns the stream saved in ctx.
+func StreamFromContext(ctx context.Context) (s *Stream, ok bool) {
+	s, ok = ctx.Value(streamKey{}).(*Stream)
+	return
+}
+
+// state of transport
+type transportState int
+
+const (
+	reachable transportState = iota
+	closing
+	draining
+)
+
+// ServerConfig consists of all the configurations to establish a server transport.
+type ServerConfig struct {
+	MaxStreams            uint32
+	AuthInfo              credentials.AuthInfo
+	InTapHandle           tap.ServerInHandle
+	StatsHandler          stats.Handler
+	KeepaliveParams       keepalive.ServerParameters
+	KeepalivePolicy       keepalive.EnforcementPolicy
+	InitialWindowSize     int32
+	InitialConnWindowSize int32
+	WriteBufferSize       int
+	ReadBufferSize        int
+}
+
+// NewServerTransport creates a ServerTransport with conn or non-nil error
+// if it fails.
+func NewServerTransport(protocol string, conn net.Conn, config *ServerConfig) (ServerTransport, error) {
+	return newHTTP2Server(conn, config)
+}
+
+// ConnectOptions covers all relevant options for communicating with the server.
+type ConnectOptions struct {
+	// UserAgent is the application user agent.
+	UserAgent string
+	// Authority is the :authority pseudo-header to use. This field has no effect if
+	// TransportCredentials is set.
+	Authority string
+	// Dialer specifies how to dial a network address.
+	Dialer func(context.Context, string) (net.Conn, error)
+	// FailOnNonTempDialError specifies if gRPC fails on non-temporary dial errors.
+	FailOnNonTempDialError bool
+	// PerRPCCredentials stores the PerRPCCredentials required to issue RPCs.
+	PerRPCCredentials []credentials.PerRPCCredentials
+	// TransportCredentials stores the Authenticator required to setup a client connection.
+	TransportCredentials credentials.TransportCredentials
+	// KeepaliveParams stores the keepalive parameters.
+	KeepaliveParams keepalive.ClientParameters
+	// StatsHandler stores the handler for stats.
+	StatsHandler stats.Handler
+	// InitialWindowSize sets the initial window size for a stream.
+	InitialWindowSize int32
+	// InitialConnWindowSize sets the initial window size for a connection.
+	InitialConnWindowSize int32
+	// WriteBufferSize sets the size of write buffer which in turn determines how much data can be batched before it's written on the wire.
+	WriteBufferSize int
+	// ReadBufferSize sets the size of read buffer, which in turn determines how much data can be read at most for one read syscall.
+	ReadBufferSize int
+}
+
+// TargetInfo contains the information of the target such as network address and metadata.
+type TargetInfo struct {
+	Addr      string
+	Metadata  interface{}
+	Authority string
+}
+
+// NewClientTransport establishes the transport with the required ConnectOptions
+// and returns it to the caller.
+func NewClientTransport(connectCtx, ctx context.Context, target TargetInfo, opts ConnectOptions, onSuccess func()) (ClientTransport, error) {
+	return newHTTP2Client(connectCtx, ctx, target, opts, onSuccess)
+}
+
+// Options provides additional hints and information for message
+// transmission.
+type Options struct {
+	// Last indicates whether this write is the last piece for
+	// this stream.
+	Last bool
+
+	// Delay is a hint to the transport implementation for whether
+	// the data could be buffered for a batching write. The
+	// transport implementation may ignore the hint.
+	Delay bool
+}
+
+// CallHdr carries the information of a particular RPC.
+type CallHdr struct {
+	// Host specifies the peer's host.
+	Host string
+
+	// Method specifies the operation to perform.
+	Method string
+
+	// SendCompress specifies the compression algorithm applied on
+	// outbound message.
+	SendCompress string
+
+	// Creds specifies credentials.PerRPCCredentials for a call.
+	Creds credentials.PerRPCCredentials
+
+	// Flush indicates whether a new stream command should be sent
+	// to the peer without waiting for the first data. This is
+	// only a hint.
+	// If it's true, the transport may modify the flush decision
+	// for performance purposes.
+	// If it's false, new stream will never be flushed.
+	Flush bool
+
+	// ContentSubtype specifies the content-subtype for a request. For example, a
+	// content-subtype of "proto" will result in a content-type of
+	// "application/grpc+proto". The value of ContentSubtype must be all
+	// lowercase, otherwise the behavior is undefined. See
+	// https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md#requests
+	// for more details.
+	ContentSubtype string
+}
+
+// ClientTransport is the common interface for all gRPC client-side transport
+// implementations.
+type ClientTransport interface {
+	// Close tears down this transport. Once it returns, the transport
+	// should not be accessed any more. The caller must make sure this
+	// is called only once.
+	Close() error
+
+	// GracefulClose starts to tear down the transport. It stops accepting
+	// new RPCs and wait the completion of the pending RPCs.
+	GracefulClose() error
+
+	// Write sends the data for the given stream. A nil stream indicates
+	// the write is to be performed on the transport as a whole.
+	Write(s *Stream, hdr []byte, data []byte, opts *Options) error
+
+	// NewStream creates a Stream for an RPC.
+	NewStream(ctx context.Context, callHdr *CallHdr) (*Stream, error)
+
+	// CloseStream clears the footprint of a stream when the stream is
+	// not needed any more. The err indicates the error incurred when
+	// CloseStream is called. Must be called when a stream is finished
+	// unless the associated transport is closing.
+	CloseStream(stream *Stream, err error)
+
+	// Error returns a channel that is closed when some I/O error
+	// happens. Typically the caller should have a goroutine to monitor
+	// this in order to take action (e.g., close the current transport
+	// and create a new one) in error case. It should not return nil
+	// once the transport is initiated.
+	Error() <-chan struct{}
+
+	// GoAway returns a channel that is closed when ClientTransport
+	// receives the draining signal from the server (e.g., GOAWAY frame in
+	// HTTP/2).
+	GoAway() <-chan struct{}
+
+	// GetGoAwayReason returns the reason why GoAway frame was received.
+	GetGoAwayReason() GoAwayReason
+}
+
+// ServerTransport is the common interface for all gRPC server-side transport
+// implementations.
+//
+// Methods may be called concurrently from multiple goroutines, but
+// Write methods for a given Stream will be called serially.
+type ServerTransport interface {
+	// HandleStreams receives incoming streams using the given handler.
+	HandleStreams(func(*Stream), func(context.Context, string) context.Context)
+
+	// WriteHeader sends the header metadata for the given stream.
+	// WriteHeader may not be called on all streams.
+	WriteHeader(s *Stream, md metadata.MD) error
+
+	// Write sends the data for the given stream.
+	// Write may not be called on all streams.
+	Write(s *Stream, hdr []byte, data []byte, opts *Options) error
+
+	// WriteStatus sends the status of a stream to the client.  WriteStatus is
+	// the final call made on a stream and always occurs.
+	WriteStatus(s *Stream, st *status.Status) error
+
+	// Close tears down the transport. Once it is called, the transport
+	// should not be accessed any more. All the pending streams and their
+	// handlers will be terminated asynchronously.
+	Close() error
+
+	// RemoteAddr returns the remote network address.
+	RemoteAddr() net.Addr
+
+	// Drain notifies the client this ServerTransport stops accepting new RPCs.
+	Drain()
+}
+
+// streamErrorf creates an StreamError with the specified error code and description.
+func streamErrorf(c codes.Code, format string, a ...interface{}) StreamError {
+	return StreamError{
+		Code: c,
+		Desc: fmt.Sprintf(format, a...),
+	}
+}
+
+// connectionErrorf creates an ConnectionError with the specified error description.
+func connectionErrorf(temp bool, e error, format string, a ...interface{}) ConnectionError {
+	return ConnectionError{
+		Desc: fmt.Sprintf(format, a...),
+		temp: temp,
+		err:  e,
+	}
+}
+
+// ConnectionError is an error that results in the termination of the
+// entire connection and the retry of all the active streams.
+type ConnectionError struct {
+	Desc string
+	temp bool
+	err  error
+}
+
+func (e ConnectionError) Error() string {
+	return fmt.Sprintf("connection error: desc = %q", e.Desc)
+}
+
+// Temporary indicates if this connection error is temporary or fatal.
+func (e ConnectionError) Temporary() bool {
+	return e.temp
+}
+
+// Origin returns the original error of this connection error.
+func (e ConnectionError) Origin() error {
+	// Never return nil error here.
+	// If the original error is nil, return itself.
+	if e.err == nil {
+		return e
+	}
+	return e.err
+}
+
+var (
+	// ErrConnClosing indicates that the transport is closing.
+	ErrConnClosing = connectionErrorf(true, nil, "transport is closing")
+	// errStreamDrain indicates that the stream is rejected because the
+	// connection is draining. This could be caused by goaway or balancer
+	// removing the address.
+	errStreamDrain = streamErrorf(codes.Unavailable, "the connection is draining")
+	// StatusGoAway indicates that the server sent a GOAWAY that included this
+	// stream's ID in unprocessed RPCs.
+	statusGoAway = status.New(codes.Unavailable, "the stream is rejected because server is draining the connection")
+)
+
+// TODO: See if we can replace StreamError with status package errors.
+
+// StreamError is an error that only affects one stream within a connection.
+type StreamError struct {
+	Code codes.Code
+	Desc string
+}
+
+func (e StreamError) Error() string {
+	return fmt.Sprintf("stream error: code = %s desc = %q", e.Code, e.Desc)
+}
+
+// waiters are passed to quotaPool get methods to
+// wait on in addition to waiting on quota.
+type waiters struct {
+	ctx    context.Context
+	tctx   context.Context
+	done   chan struct{}
+	goAway chan struct{}
+}
+
+// GoAwayReason contains the reason for the GoAway frame received.
+type GoAwayReason uint8
+
+const (
+	// GoAwayInvalid indicates that no GoAway frame is received.
+	GoAwayInvalid GoAwayReason = 0
+	// GoAwayNoReason is the default value when GoAway frame is received.
+	GoAwayNoReason GoAwayReason = 1
+	// GoAwayTooManyPings indicates that a GoAway frame with
+	// ErrCodeEnhanceYourCalm was received and that the debug data said
+	// "too_many_pings".
+	GoAwayTooManyPings GoAwayReason = 2
+)
+
+// loopyWriter is run in a separate go routine. It is the single code path that will
+// write data on wire.
+func loopyWriter(ctx context.Context, cbuf *controlBuffer, handler func(item) error) {
+	for {
+		select {
+		case i := <-cbuf.get():
+			cbuf.load()
+			if err := handler(i); err != nil {
+				errorf("transport: Error while handling item. Err: %v", err)
+				return
+			}
+		case <-ctx.Done():
+			return
+		}
+	hasData:
+		for {
+			select {
+			case i := <-cbuf.get():
+				cbuf.load()
+				if err := handler(i); err != nil {
+					errorf("transport: Error while handling item. Err: %v", err)
+					return
+				}
+			case <-ctx.Done():
+				return
+			default:
+				if err := handler(&flushIO{}); err != nil {
+					errorf("transport: Error while flushing. Err: %v", err)
+					return
+				}
+				break hasData
+			}
+		}
+	}
+}