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/*
*
* 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())
}