Update mattermost library (#2152)

* Update mattermost library

* Fix linting

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

@@ -0,0 +1,141 @@
+/*
+ *
+ * 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.  TCP typically limits this to 4MB, but some systems go up to 16MB.
+	// Since this is only a limit, it is safe to make it optimistic.
+	bdpLimit = (1 << 20) * 16
+	// 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/internal/transport/defaults.go

@@ -0,0 +1,55 @@
+/*
+ *
+ * Copyright 2018 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 (
+	"math"
+	"time"
+)
+
+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 = 20 * time.Second
+	defaultMaxStreamsClient       = 100
+	defaultMaxConnectionIdle      = infinity
+	defaultMaxConnectionAge       = infinity
+	defaultMaxConnectionAgeGrace  = infinity
+	defaultServerKeepaliveTime    = 2 * time.Hour
+	defaultServerKeepaliveTimeout = 20 * time.Second
+	defaultKeepalivePolicyMinTime = 5 * time.Minute
+	// max window limit set by HTTP2 Specs.
+	maxWindowSize = math.MaxInt32
+	// defaultWriteQuota is the default value for number of data
+	// bytes that each stream can schedule before some of it being
+	// flushed out.
+	defaultWriteQuota              = 64 * 1024
+	defaultClientMaxHeaderListSize = uint32(16 << 20)
+	defaultServerMaxHeaderListSize = uint32(16 << 20)
+)
+
+// MaxStreamID is the upper bound for the stream ID before the current
+// transport gracefully closes and new transport is created for subsequent RPCs.
+// This is set to 75% of 2^31-1. Streams are identified with an unsigned 31-bit
+// integer. It's exported so that tests can override it.
+var MaxStreamID = uint32(math.MaxInt32 * 3 / 4)

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

@@ -0,0 +1,215 @@
+/*
+ *
+ * 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"
+	"math"
+	"sync"
+	"sync/atomic"
+)
+
+// writeQuota is a soft limit on the amount of data a stream can
+// schedule before some of it is written out.
+type writeQuota struct {
+	quota int32
+	// get waits on read from when quota goes less than or equal to zero.
+	// replenish writes on it when quota goes positive again.
+	ch chan struct{}
+	// done is triggered in error case.
+	done <-chan struct{}
+	// replenish is called by loopyWriter to give quota back to.
+	// It is implemented as a field so that it can be updated
+	// by tests.
+	replenish func(n int)
+}
+
+func newWriteQuota(sz int32, done <-chan struct{}) *writeQuota {
+	w := &writeQuota{
+		quota: sz,
+		ch:    make(chan struct{}, 1),
+		done:  done,
+	}
+	w.replenish = w.realReplenish
+	return w
+}
+
+func (w *writeQuota) get(sz int32) error {
+	for {
+		if atomic.LoadInt32(&w.quota) > 0 {
+			atomic.AddInt32(&w.quota, -sz)
+			return nil
+		}
+		select {
+		case <-w.ch:
+			continue
+		case <-w.done:
+			return errStreamDone
+		}
+	}
+}
+
+func (w *writeQuota) realReplenish(n int) {
+	sz := int32(n)
+	a := atomic.AddInt32(&w.quota, sz)
+	b := a - sz
+	if b <= 0 && a > 0 {
+		select {
+		case w.ch <- struct{}{}:
+		default:
+		}
+	}
+}
+
+type trInFlow struct {
+	limit               uint32
+	unacked             uint32
+	effectiveWindowSize uint32
+}
+
+func (f *trInFlow) newLimit(n uint32) uint32 {
+	d := n - f.limit
+	f.limit = n
+	f.updateEffectiveWindowSize()
+	return d
+}
+
+func (f *trInFlow) onData(n uint32) uint32 {
+	f.unacked += n
+	if f.unacked >= f.limit/4 {
+		w := f.unacked
+		f.unacked = 0
+		f.updateEffectiveWindowSize()
+		return w
+	}
+	f.updateEffectiveWindowSize()
+	return 0
+}
+
+func (f *trInFlow) reset() uint32 {
+	w := f.unacked
+	f.unacked = 0
+	f.updateEffectiveWindowSize()
+	return w
+}
+
+func (f *trInFlow) updateEffectiveWindowSize() {
+	atomic.StoreUint32(&f.effectiveWindowSize, f.limit-f.unacked)
+}
+
+func (f *trInFlow) getSize() uint32 {
+	return atomic.LoadUint32(&f.effectiveWindowSize)
+}
+
+// TODO(mmukhi): Simplify this code.
+// 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) {
+	f.mu.Lock()
+	f.limit = n
+	f.mu.Unlock()
+}
+
+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 specified 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()
+	f.pendingData += n
+	if f.pendingData+f.pendingUpdate > f.limit+f.delta {
+		limit := f.limit
+		rcvd := f.pendingData + f.pendingUpdate
+		f.mu.Unlock()
+		return fmt.Errorf("received %d-bytes data exceeding the limit %d bytes", rcvd, limit)
+	}
+	f.mu.Unlock()
+	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()
+	if f.pendingData == 0 {
+		f.mu.Unlock()
+		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
+		f.mu.Unlock()
+		return wu
+	}
+	f.mu.Unlock()
+	return 0
+}

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

@@ -0,0 +1,488 @@
+/*
+ *
+ * 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 (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"strings"
+	"sync"
+	"time"
+
+	"golang.org/x/net/http2"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/internal/grpclog"
+	"google.golang.org/grpc/internal/grpcutil"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/peer"
+	"google.golang.org/grpc/stats"
+	"google.golang.org/grpc/status"
+	"google.golang.org/protobuf/proto"
+)
+
+// NewServerHandlerTransport returns a ServerTransport handling gRPC from
+// inside an http.Handler, or writes an HTTP error to w and returns an error.
+// 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 {
+		msg := "gRPC requires HTTP/2"
+		http.Error(w, msg, http.StatusBadRequest)
+		return nil, errors.New(msg)
+	}
+	if r.Method != "POST" {
+		msg := fmt.Sprintf("invalid gRPC request method %q", r.Method)
+		http.Error(w, msg, http.StatusBadRequest)
+		return nil, errors.New(msg)
+	}
+	contentType := r.Header.Get("Content-Type")
+	// TODO: do we assume contentType is lowercase? we did before
+	contentSubtype, validContentType := grpcutil.ContentSubtype(contentType)
+	if !validContentType {
+		msg := fmt.Sprintf("invalid gRPC request content-type %q", contentType)
+		http.Error(w, msg, http.StatusUnsupportedMediaType)
+		return nil, errors.New(msg)
+	}
+	if _, ok := w.(http.Flusher); !ok {
+		msg := "gRPC requires a ResponseWriter supporting http.Flusher"
+		http.Error(w, msg, http.StatusInternalServerError)
+		return nil, errors.New(msg)
+	}
+
+	var localAddr net.Addr
+	if la := r.Context().Value(http.LocalAddrContextKey); la != nil {
+		localAddr, _ = la.(net.Addr)
+	}
+	var authInfo credentials.AuthInfo
+	if r.TLS != nil {
+		authInfo = credentials.TLSInfo{State: *r.TLS, CommonAuthInfo: credentials.CommonAuthInfo{SecurityLevel: credentials.PrivacyAndIntegrity}}
+	}
+	p := peer.Peer{
+		Addr:      strAddr(r.RemoteAddr),
+		LocalAddr: localAddr,
+		AuthInfo:  authInfo,
+	}
+	st := &serverHandlerTransport{
+		rw:             w,
+		req:            r,
+		closedCh:       make(chan struct{}),
+		writes:         make(chan func()),
+		peer:           p,
+		contentType:    contentType,
+		contentSubtype: contentSubtype,
+		stats:          stats,
+	}
+	st.logger = prefixLoggerForServerHandlerTransport(st)
+
+	if v := r.Header.Get("grpc-timeout"); v != "" {
+		to, err := decodeTimeout(v)
+		if err != nil {
+			msg := fmt.Sprintf("malformed grpc-timeout: %v", err)
+			http.Error(w, msg, http.StatusBadRequest)
+			return nil, status.Error(codes.Internal, msg)
+		}
+		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) && !isWhitelistedHeader(k) {
+			continue
+		}
+		for _, v := range vv {
+			v, err := decodeMetadataHeader(k, v)
+			if err != nil {
+				msg := fmt.Sprintf("malformed binary metadata %q in header %q: %v", v, k, err)
+				http.Error(w, msg, http.StatusBadRequest)
+				return nil, status.Error(codes.Internal, msg)
+			}
+			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
+
+	headerMD metadata.MD
+
+	peer peer.Peer
+
+	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
+	logger *grpclog.PrefixLogger
+}
+
+func (ht *serverHandlerTransport) Close(err error) {
+	ht.closeOnce.Do(func() {
+		if ht.logger.V(logLevel) {
+			ht.logger.Infof("Closing: %v", err)
+		}
+		close(ht.closedCh)
+	})
+}
+
+func (ht *serverHandlerTransport) Peer() *peer.Peer {
+	return &peer.Peer{
+		Addr:      ht.peer.Addr,
+		LocalAddr: ht.peer.LocalAddr,
+		AuthInfo:  ht.peer.AuthInfo,
+	}
+}
+
+// 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 {
+	select {
+	case <-ht.closedCh:
+		return ErrConnClosing
+	case ht.writes <- fn:
+		return nil
+	}
+}
+
+func (ht *serverHandlerTransport) WriteStatus(s *Stream, st *status.Status) error {
+	ht.writeStatusMu.Lock()
+	defer ht.writeStatusMu.Unlock()
+
+	headersWritten := s.updateHeaderSent()
+	err := ht.do(func() {
+		if !headersWritten {
+			ht.writePendingHeaders(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))
+		}
+
+		s.hdrMu.Lock()
+		if p := st.Proto(); p != nil && len(p.Details) > 0 {
+			delete(s.trailer, grpcStatusDetailsBinHeader)
+			stBytes, err := proto.Marshal(p)
+			if err != nil {
+				// TODO: return error instead, when callers are able to handle it.
+				panic(err)
+			}
+
+			h.Set(grpcStatusDetailsBinHeader, encodeBinHeader(stBytes))
+		}
+
+		if len(s.trailer) > 0 {
+			for k, vv := range s.trailer {
+				// 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))
+				}
+			}
+		}
+		s.hdrMu.Unlock()
+	})
+
+	if err == nil { // transport has not been closed
+		// Note: The trailer fields are compressed with hpack after this call returns.
+		// No WireLength field is set here.
+		for _, sh := range ht.stats {
+			sh.HandleRPC(s.Context(), &stats.OutTrailer{
+				Trailer: s.trailer.Copy(),
+			})
+		}
+	}
+	ht.Close(errors.New("finished writing status"))
+	return err
+}
+
+// writePendingHeaders sets common and custom headers on the first
+// write call (Write, WriteHeader, or WriteStatus)
+func (ht *serverHandlerTransport) writePendingHeaders(s *Stream) {
+	ht.writeCommonHeaders(s)
+	ht.writeCustomHeaders(s)
+}
+
+// writeCommonHeaders sets common headers on the first write
+// call (Write, WriteHeader, or WriteStatus).
+func (ht *serverHandlerTransport) writeCommonHeaders(s *Stream) {
+	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)
+	}
+}
+
+// writeCustomHeaders sets custom headers set on the stream via SetHeader
+// on the first write call (Write, WriteHeader, or WriteStatus)
+func (ht *serverHandlerTransport) writeCustomHeaders(s *Stream) {
+	h := ht.rw.Header()
+
+	s.hdrMu.Lock()
+	for k, vv := range s.header {
+		if isReservedHeader(k) {
+			continue
+		}
+		for _, v := range vv {
+			h.Add(k, encodeMetadataHeader(k, v))
+		}
+	}
+
+	s.hdrMu.Unlock()
+}
+
+func (ht *serverHandlerTransport) Write(s *Stream, hdr []byte, data []byte, opts *Options) error {
+	headersWritten := s.updateHeaderSent()
+	return ht.do(func() {
+		if !headersWritten {
+			ht.writePendingHeaders(s)
+		}
+		ht.rw.Write(hdr)
+		ht.rw.Write(data)
+		ht.rw.(http.Flusher).Flush()
+	})
+}
+
+func (ht *serverHandlerTransport) WriteHeader(s *Stream, md metadata.MD) error {
+	if err := s.SetHeader(md); err != nil {
+		return err
+	}
+
+	headersWritten := s.updateHeaderSent()
+	err := ht.do(func() {
+		if !headersWritten {
+			ht.writePendingHeaders(s)
+		}
+
+		ht.rw.WriteHeader(200)
+		ht.rw.(http.Flusher).Flush()
+	})
+
+	if err == nil {
+		for _, sh := range ht.stats {
+			// Note: The header fields are compressed with hpack after this call returns.
+			// No WireLength field is set here.
+			sh.HandleRPC(s.Context(), &stats.OutHeader{
+				Header:      md.Copy(),
+				Compression: s.sendCompress,
+			})
+		}
+	}
+	return err
+}
+
+func (ht *serverHandlerTransport) HandleStreams(ctx context.Context, startStream func(*Stream)) {
+	// With this transport type there will be exactly 1 stream: this HTTP request.
+	var cancel context.CancelFunc
+	if ht.timeoutSet {
+		ctx, cancel = context.WithTimeout(ctx, ht.timeout)
+	} else {
+		ctx, cancel = context.WithCancel(ctx)
+	}
+
+	// requestOver is closed when the status has been written via WriteStatus.
+	requestOver := make(chan struct{})
+	go func() {
+		select {
+		case <-requestOver:
+		case <-ht.closedCh:
+		case <-ht.req.Context().Done():
+		}
+		cancel()
+		ht.Close(errors.New("request is done processing"))
+	}()
+
+	ctx = metadata.NewIncomingContext(ctx, ht.headerMD)
+	req := ht.req
+	s := &Stream{
+		id:               0, // irrelevant
+		ctx:              ctx,
+		requestRead:      func(int) {},
+		cancel:           cancel,
+		buf:              newRecvBuffer(),
+		st:               ht,
+		method:           req.URL.Path,
+		recvCompress:     req.Header.Get("grpc-encoding"),
+		contentSubtype:   ht.contentSubtype,
+		headerWireLength: 0, // won't have access to header wire length until golang/go#18997.
+	}
+	s.trReader = &transportReader{
+		reader:        &recvBufferReader{ctx: s.ctx, ctxDone: s.ctx.Done(), recv: s.buf, freeBuffer: func(*bytes.Buffer) {}},
+		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{buffer: bytes.NewBuffer(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 := <-ht.writes:
+			fn()
+		case <-ht.closedCh:
+			return
+		}
+	}
+}
+
+func (ht *serverHandlerTransport) IncrMsgSent() {}
+
+func (ht *serverHandlerTransport) IncrMsgRecv() {}
+
+func (ht *serverHandlerTransport) Drain(debugData string) {
+	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
+//   - an error from the status package
+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 status.Error(code, se.Error())
+		}
+	}
+	if strings.Contains(err.Error(), "body closed by handler") {
+		return status.Error(codes.Canceled, err.Error())
+	}
+	return connectionErrorf(true, err, err.Error())
+}

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

@@ -0,0 +1,465 @@
+/*
+ *
+ * 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"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"io"
+	"math"
+	"net"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+	"unicode/utf8"
+
+	"golang.org/x/net/http2"
+	"golang.org/x/net/http2/hpack"
+	"google.golang.org/grpc/codes"
+)
+
+const (
+	// http2MaxFrameLen specifies the max length of a HTTP2 frame.
+	http2MaxFrameLen = 16384 // 16KB frame
+	// https://httpwg.org/specs/rfc7540.html#SettingValues
+	http2InitHeaderTableSize = 4096
+)
+
+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.Internal,
+	}
+	// HTTPStatusConvTab is the HTTP status code to gRPC error code conversion table.
+	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,
+	}
+)
+
+var grpcStatusDetailsBinHeader = "grpc-status-details-bin"
+
+// 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",
+		"user-agent",
+		"grpc-message-type",
+		"grpc-encoding",
+		"grpc-message",
+		"grpc-status",
+		"grpc-timeout",
+		// Intentionally exclude grpc-previous-rpc-attempts and
+		// grpc-retry-pushback-ms, which are "reserved", but their API
+		// intentionally works via metadata.
+		"te":
+		return true
+	default:
+		return false
+	}
+}
+
+// isWhitelistedHeader checks whether hdr should be propagated into metadata
+// visible to users, even though it is classified as "reserved", above.
+func isWhitelistedHeader(hdr string) bool {
+	switch hdr {
+	case ":authority", "user-agent":
+		return true
+	default:
+		return false
+	}
+}
+
+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
+}
+
+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
+}
+
+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)
+	}
+	if size > 9 {
+		// Spec allows for 8 digits plus the unit.
+		return 0, fmt.Errorf("transport: timeout string is too long: %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
+	}
+	const maxHours = math.MaxInt64 / int64(time.Hour)
+	if d == time.Hour && t > maxHours {
+		// This timeout would overflow math.MaxInt64; clamp it.
+		return time.Duration(math.MaxInt64), nil
+	}
+	return d * time.Duration(t), nil
+}
+
+const (
+	spaceByte   = ' '
+	tildeByte   = '~'
+	percentByte = '%'
+)
+
+// encodeGrpcMessage is used to encode status code in header field
+// "grpc-message". It does percent encoding and also replaces invalid utf-8
+// characters with Unicode replacement character.
+//
+// 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 <= tildeByte && c != percentByte) {
+			return encodeGrpcMessageUnchecked(msg)
+		}
+	}
+	return msg
+}
+
+func encodeGrpcMessageUnchecked(msg string) string {
+	var sb strings.Builder
+	for len(msg) > 0 {
+		r, size := utf8.DecodeRuneInString(msg)
+		for _, b := range []byte(string(r)) {
+			if size > 1 {
+				// If size > 1, r is not ascii. Always do percent encoding.
+				fmt.Fprintf(&sb, "%%%02X", b)
+				continue
+			}
+
+			// The for loop is necessary even if size == 1. r could be
+			// utf8.RuneError.
+			//
+			// fmt.Sprintf("%%%02X", utf8.RuneError) gives "%FFFD".
+			if b >= spaceByte && b <= tildeByte && b != percentByte {
+				sb.WriteByte(b)
+			} else {
+				fmt.Fprintf(&sb, "%%%02X", b)
+			}
+		}
+		msg = msg[size:]
+	}
+	return sb.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 sb strings.Builder
+	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 {
+				sb.WriteByte(c)
+			} else {
+				sb.WriteByte(byte(parsed))
+				i += 2
+			}
+		} else {
+			sb.WriteByte(c)
+		}
+	}
+	return sb.String()
+}
+
+type bufWriter struct {
+	pool      *sync.Pool
+	buf       []byte
+	offset    int
+	batchSize int
+	conn      net.Conn
+	err       error
+}
+
+func newBufWriter(conn net.Conn, batchSize int, pool *sync.Pool) *bufWriter {
+	w := &bufWriter{
+		batchSize: batchSize,
+		conn:      conn,
+		pool:      pool,
+	}
+	// this indicates that we should use non shared buf
+	if pool == nil {
+		w.buf = make([]byte, batchSize)
+	}
+	return w
+}
+
+func (w *bufWriter) Write(b []byte) (n int, err error) {
+	if w.err != nil {
+		return 0, w.err
+	}
+	if w.batchSize == 0 { // Buffer has been disabled.
+		n, err = w.conn.Write(b)
+		return n, toIOError(err)
+	}
+	if w.buf == nil {
+		b := w.pool.Get().(*[]byte)
+		w.buf = *b
+	}
+	for len(b) > 0 {
+		nn := copy(w.buf[w.offset:], b)
+		b = b[nn:]
+		w.offset += nn
+		n += nn
+		if w.offset >= w.batchSize {
+			err = w.flushKeepBuffer()
+		}
+	}
+	return n, err
+}
+
+func (w *bufWriter) Flush() error {
+	err := w.flushKeepBuffer()
+	// Only release the buffer if we are in a "shared" mode
+	if w.buf != nil && w.pool != nil {
+		b := w.buf
+		w.pool.Put(&b)
+		w.buf = nil
+	}
+	return err
+}
+
+func (w *bufWriter) flushKeepBuffer() error {
+	if w.err != nil {
+		return w.err
+	}
+	if w.offset == 0 {
+		return nil
+	}
+	_, w.err = w.conn.Write(w.buf[:w.offset])
+	w.err = toIOError(w.err)
+	w.offset = 0
+	return w.err
+}
+
+type ioError struct {
+	error
+}
+
+func (i ioError) Unwrap() error {
+	return i.error
+}
+
+func isIOError(err error) bool {
+	return errors.As(err, &ioError{})
+}
+
+func toIOError(err error) error {
+	if err == nil {
+		return nil
+	}
+	return ioError{error: err}
+}
+
+type framer struct {
+	writer *bufWriter
+	fr     *http2.Framer
+}
+
+var writeBufferPoolMap map[int]*sync.Pool = make(map[int]*sync.Pool)
+var writeBufferMutex sync.Mutex
+
+func newFramer(conn net.Conn, writeBufferSize, readBufferSize int, sharedWriteBuffer bool, maxHeaderListSize uint32) *framer {
+	if writeBufferSize < 0 {
+		writeBufferSize = 0
+	}
+	var r io.Reader = conn
+	if readBufferSize > 0 {
+		r = bufio.NewReaderSize(r, readBufferSize)
+	}
+	var pool *sync.Pool
+	if sharedWriteBuffer {
+		pool = getWriteBufferPool(writeBufferSize)
+	}
+	w := newBufWriter(conn, writeBufferSize, pool)
+	f := &framer{
+		writer: w,
+		fr:     http2.NewFramer(w, r),
+	}
+	f.fr.SetMaxReadFrameSize(http2MaxFrameLen)
+	// 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.MaxHeaderListSize = maxHeaderListSize
+	f.fr.ReadMetaHeaders = hpack.NewDecoder(http2InitHeaderTableSize, nil)
+	return f
+}
+
+func getWriteBufferPool(writeBufferSize int) *sync.Pool {
+	writeBufferMutex.Lock()
+	defer writeBufferMutex.Unlock()
+	size := writeBufferSize * 2
+	pool, ok := writeBufferPoolMap[size]
+	if ok {
+		return pool
+	}
+	pool = &sync.Pool{
+		New: func() any {
+			b := make([]byte, size)
+			return &b
+		},
+	}
+	writeBufferPoolMap[size] = pool
+	return pool
+}
+
+// parseDialTarget returns the network and address to pass to dialer.
+func parseDialTarget(target string) (string, string) {
+	net := "tcp"
+	m1 := strings.Index(target, ":")
+	m2 := strings.Index(target, ":/")
+	// handle unix:addr which will fail with url.Parse
+	if m1 >= 0 && m2 < 0 {
+		if n := target[0:m1]; n == "unix" {
+			return n, target[m1+1:]
+		}
+	}
+	if m2 >= 0 {
+		t, err := url.Parse(target)
+		if err != nil {
+			return net, target
+		}
+		scheme := t.Scheme
+		addr := t.Path
+		if scheme == "unix" {
+			if addr == "" {
+				addr = t.Host
+			}
+			return scheme, addr
+		}
+	}
+	return net, target
+}

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

@@ -0,0 +1,40 @@
+/*
+ *
+ * Copyright 2023 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"
+
+	"google.golang.org/grpc/grpclog"
+	internalgrpclog "google.golang.org/grpc/internal/grpclog"
+)
+
+var logger = grpclog.Component("transport")
+
+func prefixLoggerForServerTransport(p *http2Server) *internalgrpclog.PrefixLogger {
+	return internalgrpclog.NewPrefixLogger(logger, fmt.Sprintf("[server-transport %p] ", p))
+}
+
+func prefixLoggerForServerHandlerTransport(p *serverHandlerTransport) *internalgrpclog.PrefixLogger {
+	return internalgrpclog.NewPrefixLogger(logger, fmt.Sprintf("[server-handler-transport %p] ", p))
+}
+
+func prefixLoggerForClientTransport(p *http2Client) *internalgrpclog.PrefixLogger {
+	return internalgrpclog.NewPrefixLogger(logger, fmt.Sprintf("[client-transport %p] ", p))
+}

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

@@ -0,0 +1,46 @@
+/*
+ *
+ * Copyright 2020 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 networktype declares the network type to be used in the default
+// dialer. Attribute of a resolver.Address.
+package networktype
+
+import (
+	"google.golang.org/grpc/resolver"
+)
+
+// keyType is the key to use for storing State in Attributes.
+type keyType string
+
+const key = keyType("grpc.internal.transport.networktype")
+
+// Set returns a copy of the provided address with attributes containing networkType.
+func Set(address resolver.Address, networkType string) resolver.Address {
+	address.Attributes = address.Attributes.WithValue(key, networkType)
+	return address
+}
+
+// Get returns the network type in the resolver.Address and true, or "", false
+// if not present.
+func Get(address resolver.Address) (string, bool) {
+	v := address.Attributes.Value(key)
+	if v == nil {
+		return "", false
+	}
+	return v.(string), true
+}

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

@@ -0,0 +1,144 @@
+/*
+ *
+ * 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 (
+	"bufio"
+	"context"
+	"encoding/base64"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+
+	"google.golang.org/grpc/internal"
+)
+
+const proxyAuthHeaderKey = "Proxy-Authorization"
+
+var (
+	// The following variable will be overwritten in the tests.
+	httpProxyFromEnvironment = http.ProxyFromEnvironment
+)
+
+func mapAddress(address string) (*url.URL, error) {
+	req := &http.Request{
+		URL: &url.URL{
+			Scheme: "https",
+			Host:   address,
+		},
+	}
+	url, err := httpProxyFromEnvironment(req)
+	if err != nil {
+		return nil, err
+	}
+	return url, nil
+}
+
+// To read a response from a net.Conn, http.ReadResponse() takes a bufio.Reader.
+// It's possible that this reader reads more than what's need for the response and stores
+// those bytes in the buffer.
+// bufConn wraps the original net.Conn and the bufio.Reader to make sure we don't lose the
+// bytes in the buffer.
+type bufConn struct {
+	net.Conn
+	r io.Reader
+}
+
+func (c *bufConn) Read(b []byte) (int, error) {
+	return c.r.Read(b)
+}
+
+func basicAuth(username, password string) string {
+	auth := username + ":" + password
+	return base64.StdEncoding.EncodeToString([]byte(auth))
+}
+
+func doHTTPConnectHandshake(ctx context.Context, conn net.Conn, backendAddr string, proxyURL *url.URL, grpcUA string) (_ net.Conn, err error) {
+	defer func() {
+		if err != nil {
+			conn.Close()
+		}
+	}()
+
+	req := &http.Request{
+		Method: http.MethodConnect,
+		URL:    &url.URL{Host: backendAddr},
+		Header: map[string][]string{"User-Agent": {grpcUA}},
+	}
+	if t := proxyURL.User; t != nil {
+		u := t.Username()
+		p, _ := t.Password()
+		req.Header.Add(proxyAuthHeaderKey, "Basic "+basicAuth(u, p))
+	}
+
+	if err := sendHTTPRequest(ctx, req, conn); err != nil {
+		return nil, fmt.Errorf("failed to write the HTTP request: %v", err)
+	}
+
+	r := bufio.NewReader(conn)
+	resp, err := http.ReadResponse(r, req)
+	if err != nil {
+		return nil, fmt.Errorf("reading server HTTP response: %v", err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		dump, err := httputil.DumpResponse(resp, true)
+		if err != nil {
+			return nil, fmt.Errorf("failed to do connect handshake, status code: %s", resp.Status)
+		}
+		return nil, fmt.Errorf("failed to do connect handshake, response: %q", dump)
+	}
+
+	return &bufConn{Conn: conn, r: r}, nil
+}
+
+// proxyDial dials, connecting to a proxy first if necessary. Checks if a proxy
+// is necessary, dials, does the HTTP CONNECT handshake, and returns the
+// connection.
+func proxyDial(ctx context.Context, addr string, grpcUA string) (net.Conn, error) {
+	newAddr := addr
+	proxyURL, err := mapAddress(addr)
+	if err != nil {
+		return nil, err
+	}
+	if proxyURL != nil {
+		newAddr = proxyURL.Host
+	}
+
+	conn, err := internal.NetDialerWithTCPKeepalive().DialContext(ctx, "tcp", newAddr)
+	if err != nil {
+		return nil, err
+	}
+	if proxyURL == nil {
+		// proxy is disabled if proxyURL is nil.
+		return conn, err
+	}
+	return doHTTPConnectHandshake(ctx, conn, addr, proxyURL, grpcUA)
+}
+
+func sendHTTPRequest(ctx context.Context, req *http.Request, conn net.Conn) error {
+	req = req.WithContext(ctx)
+	if err := req.Write(conn); err != nil {
+		return fmt.Errorf("failed to write the HTTP request: %v", err)
+	}
+	return nil
+}

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

@@ -0,0 +1,851 @@
+/*
+ *
+ * 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 (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/internal/channelz"
+	"google.golang.org/grpc/keepalive"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/peer"
+	"google.golang.org/grpc/resolver"
+	"google.golang.org/grpc/stats"
+	"google.golang.org/grpc/status"
+	"google.golang.org/grpc/tap"
+)
+
+const logLevel = 2
+
+type bufferPool struct {
+	pool sync.Pool
+}
+
+func newBufferPool() *bufferPool {
+	return &bufferPool{
+		pool: sync.Pool{
+			New: func() any {
+				return new(bytes.Buffer)
+			},
+		},
+	}
+}
+
+func (p *bufferPool) get() *bytes.Buffer {
+	return p.pool.Get().(*bytes.Buffer)
+}
+
+func (p *bufferPool) put(b *bytes.Buffer) {
+	p.pool.Put(b)
+}
+
+// recvMsg represents the received msg from the transport. All transport
+// protocol specific info has been removed.
+type recvMsg struct {
+	buffer *bytes.Buffer
+	// 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 buffer.Unbounded only in the fact that it
+// holds a channel of recvMsg structs instead of objects implementing "item"
+// interface. recvBuffer is written to much more often and using strict recvMsg
+// structs helps avoid allocation in "recvBuffer.put"
+type recvBuffer struct {
+	c       chan recvMsg
+	mu      sync.Mutex
+	backlog []recvMsg
+	err     error
+}
+
+func newRecvBuffer() *recvBuffer {
+	b := &recvBuffer{
+		c: make(chan recvMsg, 1),
+	}
+	return b
+}
+
+func (b *recvBuffer) put(r recvMsg) {
+	b.mu.Lock()
+	if b.err != nil {
+		b.mu.Unlock()
+		// An error had occurred earlier, don't accept more
+		// data or errors.
+		return
+	}
+	b.err = r.err
+	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 {
+	closeStream func(error) // Closes the client transport stream with the given error and nil trailer metadata.
+	ctx         context.Context
+	ctxDone     <-chan struct{} // cache of ctx.Done() (for performance).
+	recv        *recvBuffer
+	last        *bytes.Buffer // Stores the remaining data in the previous calls.
+	err         error
+	freeBuffer  func(*bytes.Buffer)
+}
+
+// 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
+	}
+	if r.last != nil {
+		// Read remaining data left in last call.
+		copied, _ := r.last.Read(p)
+		if r.last.Len() == 0 {
+			r.freeBuffer(r.last)
+			r.last = nil
+		}
+		return copied, nil
+	}
+	if r.closeStream != nil {
+		n, r.err = r.readClient(p)
+	} else {
+		n, r.err = r.read(p)
+	}
+	return n, r.err
+}
+
+func (r *recvBufferReader) read(p []byte) (n int, err error) {
+	select {
+	case <-r.ctxDone:
+		return 0, ContextErr(r.ctx.Err())
+	case m := <-r.recv.get():
+		return r.readAdditional(m, p)
+	}
+}
+
+func (r *recvBufferReader) readClient(p []byte) (n int, err error) {
+	// If the context is canceled, then closes the stream with nil metadata.
+	// closeStream writes its error parameter to r.recv as a recvMsg.
+	// r.readAdditional acts on that message and returns the necessary error.
+	select {
+	case <-r.ctxDone:
+		// Note that this adds the ctx error to the end of recv buffer, and
+		// reads from the head. This will delay the error until recv buffer is
+		// empty, thus will delay ctx cancellation in Recv().
+		//
+		// It's done this way to fix a race between ctx cancel and trailer. The
+		// race was, stream.Recv() may return ctx error if ctxDone wins the
+		// race, but stream.Trailer() may return a non-nil md because the stream
+		// was not marked as done when trailer is received. This closeStream
+		// call will mark stream as done, thus fix the race.
+		//
+		// TODO: delaying ctx error seems like a unnecessary side effect. What
+		// we really want is to mark the stream as done, and return ctx error
+		// faster.
+		r.closeStream(ContextErr(r.ctx.Err()))
+		m := <-r.recv.get()
+		return r.readAdditional(m, p)
+	case m := <-r.recv.get():
+		return r.readAdditional(m, p)
+	}
+}
+
+func (r *recvBufferReader) readAdditional(m recvMsg, p []byte) (n int, err error) {
+	r.recv.load()
+	if m.err != nil {
+		return 0, m.err
+	}
+	copied, _ := m.buffer.Read(p)
+	if m.buffer.Len() == 0 {
+		r.freeBuffer(m.buffer)
+		r.last = nil
+	} else {
+		r.last = m.buffer
+	}
+	return copied, nil
+}
+
+type streamState uint32
+
+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
+	ct           *http2Client       // nil for server side Stream
+	ctx          context.Context    // the associated context of the stream
+	cancel       context.CancelFunc // always nil for client side Stream
+	done         chan struct{}      // closed at the end of stream to unblock writers. On the client side.
+	doneFunc     func()             // invoked at the end of stream on client side.
+	ctxDone      <-chan struct{}    // same as done chan but for server side. Cache of ctx.Done() (for performance)
+	method       string             // the associated RPC method of the stream
+	recvCompress string
+	sendCompress string
+	buf          *recvBuffer
+	trReader     io.Reader
+	fc           *inFlow
+	wq           *writeQuota
+
+	// Holds compressor names passed in grpc-accept-encoding metadata from the
+	// client. This is empty for the client side stream.
+	clientAdvertisedCompressors string
+	// Callback to state application's intentions to read data. This
+	// is used to adjust flow control, if needed.
+	requestRead func(int)
+
+	headerChan       chan struct{} // closed to indicate the end of header metadata.
+	headerChanClosed uint32        // set when headerChan is closed. Used to avoid closing headerChan multiple times.
+	// headerValid indicates whether a valid header was received.  Only
+	// meaningful after headerChan is closed (always call waitOnHeader() before
+	// reading its value).  Not valid on server side.
+	headerValid      bool
+	headerWireLength int // Only set on server side.
+
+	// hdrMu protects header and trailer metadata on the server-side.
+	hdrMu sync.Mutex
+	// On client side, header keeps the received header metadata.
+	//
+	// On server side, header keeps the header set by SetHeader(). The complete
+	// header will merged into this after t.WriteHeader() is called.
+	header  metadata.MD
+	trailer metadata.MD // the key-value map of trailer metadata.
+
+	noHeaders bool // set if the client never received headers (set only after the stream is done).
+
+	// On the server-side, headerSent is atomically set to 1 when the headers are sent out.
+	headerSent uint32
+
+	state streamState
+
+	// On client-side it is the status error received from the server.
+	// On server-side it is unused.
+	status *status.Status
+
+	bytesReceived uint32 // indicates whether any bytes have been received on this stream
+	unprocessed   uint32 // 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
+}
+
+// isHeaderSent is only valid on the server-side.
+func (s *Stream) isHeaderSent() bool {
+	return atomic.LoadUint32(&s.headerSent) == 1
+}
+
+// updateHeaderSent updates headerSent and returns true
+// if it was alreay set. It is valid only on server-side.
+func (s *Stream) updateHeaderSent() bool {
+	return atomic.SwapUint32(&s.headerSent, 1) == 1
+}
+
+func (s *Stream) swapState(st streamState) streamState {
+	return streamState(atomic.SwapUint32((*uint32)(&s.state), uint32(st)))
+}
+
+func (s *Stream) compareAndSwapState(oldState, newState streamState) bool {
+	return atomic.CompareAndSwapUint32((*uint32)(&s.state), uint32(oldState), uint32(newState))
+}
+
+func (s *Stream) getState() streamState {
+	return streamState(atomic.LoadUint32((*uint32)(&s.state)))
+}
+
+func (s *Stream) waitOnHeader() {
+	if s.headerChan == nil {
+		// On the server headerChan is always nil since a stream originates
+		// only after having received headers.
+		return
+	}
+	select {
+	case <-s.ctx.Done():
+		// Close the stream to prevent headers/trailers from changing after
+		// this function returns.
+		s.ct.CloseStream(s, ContextErr(s.ctx.Err()))
+		// headerChan could possibly not be closed yet if closeStream raced
+		// with operateHeaders; wait until it is closed explicitly here.
+		<-s.headerChan
+	case <-s.headerChan:
+	}
+}
+
+// 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 {
+	s.waitOnHeader()
+	return s.recvCompress
+}
+
+// SetSendCompress sets the compression algorithm to the stream.
+func (s *Stream) SetSendCompress(name string) error {
+	if s.isHeaderSent() || s.getState() == streamDone {
+		return errors.New("transport: set send compressor called after headers sent or stream done")
+	}
+
+	s.sendCompress = name
+	return nil
+}
+
+// SendCompress returns the send compressor name.
+func (s *Stream) SendCompress() string {
+	return s.sendCompress
+}
+
+// ClientAdvertisedCompressors returns the compressor names advertised by the
+// client via grpc-accept-encoding header.
+func (s *Stream) ClientAdvertisedCompressors() string {
+	return s.clientAdvertisedCompressors
+}
+
+// Done returns a channel which is closed when it receives the final status
+// from the server.
+func (s *Stream) Done() <-chan struct{} {
+	return s.done
+}
+
+// Header returns the header metadata of the stream.
+//
+// On client side, it 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.
+//
+// On server side, it returns the out header after t.WriteHeader is called.  It
+// does not block and must not be called until after WriteHeader.
+func (s *Stream) Header() (metadata.MD, error) {
+	if s.headerChan == nil {
+		// On server side, return the header in stream. It will be the out
+		// header after t.WriteHeader is called.
+		return s.header.Copy(), nil
+	}
+	s.waitOnHeader()
+
+	if !s.headerValid || s.noHeaders {
+		return nil, s.status.Err()
+	}
+
+	return s.header.Copy(), nil
+}
+
+// TrailersOnly blocks until a header or trailers-only frame is received and
+// then returns true if the stream was trailers-only.  If the stream ends
+// before headers are received, returns true, nil.  Client-side only.
+func (s *Stream) TrailersOnly() bool {
+	s.waitOnHeader()
+	return s.noHeaders
+}
+
+// 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.
+// It can be safely read only after stream has ended that is either read
+// or write have returned io.EOF.
+func (s *Stream) Trailer() metadata.MD {
+	c := s.trailer.Copy()
+	return c
+}
+
+// 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
+}
+
+// SetContext sets the context of the stream. This will be deleted once the
+// stats handler callouts all move to gRPC layer.
+func (s *Stream) SetContext(ctx context.Context) {
+	s.ctx = ctx
+}
+
+// Method returns the method for the stream.
+func (s *Stream) Method() string {
+	return s.method
+}
+
+// Status returns the status received from the server.
+// Status can be read safely only after the stream has ended,
+// that is, after Done() is closed.
+func (s *Stream) Status() *status.Status {
+	return s.status
+}
+
+// HeaderWireLength returns the size of the headers of the stream as received
+// from the wire. Valid only on the server.
+func (s *Stream) HeaderWireLength() int {
+	return s.headerWireLength
+}
+
+// SetHeader sets the header metadata. This can be called multiple times.
+// Server side only.
+// This should not be called in parallel to other data writes.
+func (s *Stream) SetHeader(md metadata.MD) error {
+	if md.Len() == 0 {
+		return nil
+	}
+	if s.isHeaderSent() || s.getState() == streamDone {
+		return ErrIllegalHeaderWrite
+	}
+	s.hdrMu.Lock()
+	s.header = metadata.Join(s.header, md)
+	s.hdrMu.Unlock()
+	return nil
+}
+
+// SendHeader sends the given header metadata. The given metadata is
+// combined with any metadata set by previous calls to SetHeader and
+// then written to the transport stream.
+func (s *Stream) SendHeader(md metadata.MD) error {
+	return s.st.WriteHeader(s, md)
+}
+
+// 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.
+// This should not be called parallel to other data writes.
+func (s *Stream) SetTrailer(md metadata.MD) error {
+	if md.Len() == 0 {
+		return nil
+	}
+	if s.getState() == streamDone {
+		return ErrIllegalHeaderWrite
+	}
+	s.hdrMu.Lock()
+	s.trailer = metadata.Join(s.trailer, md)
+	s.hdrMu.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
+}
+
+// BytesReceived indicates whether any bytes have been received on this stream.
+func (s *Stream) BytesReceived() bool {
+	return atomic.LoadUint32(&s.bytesReceived) == 1
+}
+
+// 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 {
+	return atomic.LoadUint32(&s.unprocessed) == 1
+}
+
+// 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)
+}
+
+// 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
+	ConnectionTimeout     time.Duration
+	Credentials           credentials.TransportCredentials
+	InTapHandle           tap.ServerInHandle
+	StatsHandlers         []stats.Handler
+	KeepaliveParams       keepalive.ServerParameters
+	KeepalivePolicy       keepalive.EnforcementPolicy
+	InitialWindowSize     int32
+	InitialConnWindowSize int32
+	WriteBufferSize       int
+	ReadBufferSize        int
+	SharedWriteBuffer     bool
+	ChannelzParentID      *channelz.Identifier
+	MaxHeaderListSize     *uint32
+	HeaderTableSize       *uint32
+}
+
+// ConnectOptions covers all relevant options for communicating with the server.
+type ConnectOptions struct {
+	// UserAgent is the application user agent.
+	UserAgent 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. Only one of TransportCredentials and CredsBundle is non-nil.
+	TransportCredentials credentials.TransportCredentials
+	// CredsBundle is the credentials bundle to be used. Only one of
+	// TransportCredentials and CredsBundle is non-nil.
+	CredsBundle credentials.Bundle
+	// KeepaliveParams stores the keepalive parameters.
+	KeepaliveParams keepalive.ClientParameters
+	// StatsHandlers stores the handler for stats.
+	StatsHandlers []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
+	// SharedWriteBuffer indicates whether connections should reuse write buffer
+	SharedWriteBuffer bool
+	// ChannelzParentID sets the addrConn id which initiate the creation of this client transport.
+	ChannelzParentID *channelz.Identifier
+	// MaxHeaderListSize sets the max (uncompressed) size of header list that is prepared to be received.
+	MaxHeaderListSize *uint32
+	// UseProxy specifies if a proxy should be used.
+	UseProxy bool
+}
+
+// NewClientTransport establishes the transport with the required ConnectOptions
+// and returns it to the caller.
+func NewClientTransport(connectCtx, ctx context.Context, addr resolver.Address, opts ConnectOptions, onClose func(GoAwayReason)) (ClientTransport, error) {
+	return newHTTP2Client(connectCtx, ctx, addr, opts, onClose)
+}
+
+// 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
+}
+
+// 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
+
+	// 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
+
+	PreviousAttempts int // value of grpc-previous-rpc-attempts header to set
+
+	DoneFunc func() // called when the stream is finished
+}
+
+// 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(err error)
+
+	// GracefulClose starts to tear down the transport: the transport will stop
+	// accepting new RPCs and NewStream will return error. Once all streams are
+	// finished, the transport will close.
+	//
+	// It does not block.
+	GracefulClose()
+
+	// 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, along
+	// with a human readable string with debug info.
+	GetGoAwayReason() (GoAwayReason, string)
+
+	// RemoteAddr returns the remote network address.
+	RemoteAddr() net.Addr
+
+	// IncrMsgSent increments the number of message sent through this transport.
+	IncrMsgSent()
+
+	// IncrMsgRecv increments the number of message received through this transport.
+	IncrMsgRecv()
+}
+
+// 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(context.Context, func(*Stream))
+
+	// 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(err error)
+
+	// Peer returns the peer of the server transport.
+	Peer() *peer.Peer
+
+	// Drain notifies the client this ServerTransport stops accepting new RPCs.
+	Drain(debugData string)
+
+	// IncrMsgSent increments the number of message sent through this transport.
+	IncrMsgSent()
+
+	// IncrMsgRecv increments the number of message received through this transport.
+	IncrMsgRecv()
+}
+
+// connectionErrorf creates an ConnectionError with the specified error description.
+func connectionErrorf(temp bool, e error, format string, a ...any) 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
+}
+
+// Unwrap returns the original error of this connection error or nil when the
+// origin is nil.
+func (e ConnectionError) Unwrap() error {
+	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 = status.Error(codes.Unavailable, "the connection is draining")
+	// errStreamDone is returned from write at the client side to indiacte application
+	// layer of an error.
+	errStreamDone = errors.New("the stream is done")
+	// 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")
+)
+
+// 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
+)
+
+// channelzData is used to store channelz related data for http2Client and http2Server.
+// These fields cannot be embedded in the original structs (e.g. http2Client), since to do atomic
+// operation on int64 variable on 32-bit machine, user is responsible to enforce memory alignment.
+// Here, by grouping those int64 fields inside a struct, we are enforcing the alignment.
+type channelzData struct {
+	kpCount int64
+	// The number of streams that have started, including already finished ones.
+	streamsStarted int64
+	// Client side: The number of streams that have ended successfully by receiving
+	// EoS bit set frame from server.
+	// Server side: The number of streams that have ended successfully by sending
+	// frame with EoS bit set.
+	streamsSucceeded int64
+	streamsFailed    int64
+	// lastStreamCreatedTime stores the timestamp that the last stream gets created. It is of int64 type
+	// instead of time.Time since it's more costly to atomically update time.Time variable than int64
+	// variable. The same goes for lastMsgSentTime and lastMsgRecvTime.
+	lastStreamCreatedTime int64
+	msgSent               int64
+	msgRecv               int64
+	lastMsgSentTime       int64
+	lastMsgRecvTime       int64
+}
+
+// ContextErr converts the error from context package into a status error.
+func ContextErr(err error) error {
+	switch err {
+	case context.DeadlineExceeded:
+		return status.Error(codes.DeadlineExceeded, err.Error())
+	case context.Canceled:
+		return status.Error(codes.Canceled, err.Error())
+	}
+	return status.Errorf(codes.Internal, "Unexpected error from context packet: %v", err)
+}