553 lines
13 KiB
Go
553 lines
13 KiB
Go
// Copyright 2015 The Go Authors.
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// See https://go.googlesource.com/go/+/master/CONTRIBUTORS
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// Licensed under the same terms as Go itself:
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// https://go.googlesource.com/go/+/master/LICENSE
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package http2
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import (
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"bufio"
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"bytes"
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"crypto/tls"
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"errors"
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"fmt"
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"io"
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"log"
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"net"
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"net/http"
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"strconv"
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"strings"
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"sync"
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"github.com/bradfitz/http2/hpack"
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)
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type Transport struct {
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Fallback http.RoundTripper
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// TODO: remove this and make more general with a TLS dial hook, like http
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InsecureTLSDial bool
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connMu sync.Mutex
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conns map[string][]*clientConn // key is host:port
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}
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type clientConn struct {
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t *Transport
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tconn *tls.Conn
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tlsState *tls.ConnectionState
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connKey []string // key(s) this connection is cached in, in t.conns
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readerDone chan struct{} // closed on error
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readerErr error // set before readerDone is closed
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hdec *hpack.Decoder
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nextRes *http.Response
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mu sync.Mutex
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closed bool
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goAway *GoAwayFrame // if non-nil, the GoAwayFrame we received
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streams map[uint32]*clientStream
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nextStreamID uint32
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bw *bufio.Writer
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werr error // first write error that has occurred
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br *bufio.Reader
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fr *Framer
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// Settings from peer:
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maxFrameSize uint32
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maxConcurrentStreams uint32
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initialWindowSize uint32
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hbuf bytes.Buffer // HPACK encoder writes into this
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henc *hpack.Encoder
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}
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type clientStream struct {
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ID uint32
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resc chan resAndError
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pw *io.PipeWriter
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pr *io.PipeReader
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}
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type stickyErrWriter struct {
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w io.Writer
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err *error
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}
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func (sew stickyErrWriter) Write(p []byte) (n int, err error) {
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if *sew.err != nil {
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return 0, *sew.err
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}
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n, err = sew.w.Write(p)
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*sew.err = err
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return
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}
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func (t *Transport) RoundTrip(req *http.Request) (*http.Response, error) {
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if req.URL.Scheme != "https" {
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if t.Fallback == nil {
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return nil, errors.New("http2: unsupported scheme and no Fallback")
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}
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return t.Fallback.RoundTrip(req)
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}
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host, port, err := net.SplitHostPort(req.URL.Host)
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if err != nil {
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host = req.URL.Host
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port = "443"
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}
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for {
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cc, err := t.getClientConn(host, port)
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if err != nil {
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return nil, err
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}
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res, err := cc.roundTrip(req)
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if shouldRetryRequest(err) { // TODO: or clientconn is overloaded (too many outstanding requests)?
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continue
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}
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if err != nil {
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return nil, err
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}
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return res, nil
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}
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}
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// CloseIdleConnections closes any connections which were previously
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// connected from previous requests but are now sitting idle.
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// It does not interrupt any connections currently in use.
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func (t *Transport) CloseIdleConnections() {
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t.connMu.Lock()
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defer t.connMu.Unlock()
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for _, vv := range t.conns {
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for _, cc := range vv {
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cc.closeIfIdle()
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}
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}
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}
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var errClientConnClosed = errors.New("http2: client conn is closed")
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func shouldRetryRequest(err error) bool {
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// TODO: or GOAWAY graceful shutdown stuff
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return err == errClientConnClosed
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}
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func (t *Transport) removeClientConn(cc *clientConn) {
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t.connMu.Lock()
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defer t.connMu.Unlock()
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for _, key := range cc.connKey {
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vv, ok := t.conns[key]
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if !ok {
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continue
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}
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newList := filterOutClientConn(vv, cc)
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if len(newList) > 0 {
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t.conns[key] = newList
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} else {
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delete(t.conns, key)
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}
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}
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}
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func filterOutClientConn(in []*clientConn, exclude *clientConn) []*clientConn {
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out := in[:0]
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for _, v := range in {
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if v != exclude {
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out = append(out, v)
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}
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}
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return out
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}
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func (t *Transport) getClientConn(host, port string) (*clientConn, error) {
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t.connMu.Lock()
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defer t.connMu.Unlock()
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key := net.JoinHostPort(host, port)
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for _, cc := range t.conns[key] {
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if cc.canTakeNewRequest() {
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return cc, nil
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}
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}
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if t.conns == nil {
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t.conns = make(map[string][]*clientConn)
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}
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cc, err := t.newClientConn(host, port, key)
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if err != nil {
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return nil, err
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}
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t.conns[key] = append(t.conns[key], cc)
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return cc, nil
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}
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func (t *Transport) newClientConn(host, port, key string) (*clientConn, error) {
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cfg := &tls.Config{
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ServerName: host,
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NextProtos: []string{NextProtoTLS},
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InsecureSkipVerify: t.InsecureTLSDial,
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}
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tconn, err := tls.Dial("tcp", host+":"+port, cfg)
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if err != nil {
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return nil, err
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}
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if err := tconn.Handshake(); err != nil {
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return nil, err
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}
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if !t.InsecureTLSDial {
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if err := tconn.VerifyHostname(cfg.ServerName); err != nil {
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return nil, err
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}
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}
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state := tconn.ConnectionState()
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if p := state.NegotiatedProtocol; p != NextProtoTLS {
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// TODO(bradfitz): fall back to Fallback
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return nil, fmt.Errorf("bad protocol: %v", p)
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}
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if !state.NegotiatedProtocolIsMutual {
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return nil, errors.New("could not negotiate protocol mutually")
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}
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if _, err := tconn.Write(clientPreface); err != nil {
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return nil, err
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}
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cc := &clientConn{
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t: t,
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tconn: tconn,
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connKey: []string{key}, // TODO: cert's validated hostnames too
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tlsState: &state,
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readerDone: make(chan struct{}),
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nextStreamID: 1,
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maxFrameSize: 16 << 10, // spec default
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initialWindowSize: 65535, // spec default
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maxConcurrentStreams: 1000, // "infinite", per spec. 1000 seems good enough.
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streams: make(map[uint32]*clientStream),
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}
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cc.bw = bufio.NewWriter(stickyErrWriter{tconn, &cc.werr})
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cc.br = bufio.NewReader(tconn)
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cc.fr = NewFramer(cc.bw, cc.br)
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cc.henc = hpack.NewEncoder(&cc.hbuf)
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cc.fr.WriteSettings()
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// TODO: re-send more conn-level flow control tokens when server uses all these.
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cc.fr.WriteWindowUpdate(0, 1<<30) // um, 0x7fffffff doesn't work to Google? it hangs?
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cc.bw.Flush()
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if cc.werr != nil {
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return nil, cc.werr
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}
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// Read the obligatory SETTINGS frame
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f, err := cc.fr.ReadFrame()
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if err != nil {
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return nil, err
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}
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sf, ok := f.(*SettingsFrame)
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if !ok {
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return nil, fmt.Errorf("expected settings frame, got: %T", f)
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}
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cc.fr.WriteSettingsAck()
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cc.bw.Flush()
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sf.ForeachSetting(func(s Setting) error {
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switch s.ID {
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case SettingMaxFrameSize:
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cc.maxFrameSize = s.Val
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case SettingMaxConcurrentStreams:
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cc.maxConcurrentStreams = s.Val
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case SettingInitialWindowSize:
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cc.initialWindowSize = s.Val
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default:
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// TODO(bradfitz): handle more
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log.Printf("Unhandled Setting: %v", s)
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}
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return nil
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})
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// TODO: figure out henc size
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cc.hdec = hpack.NewDecoder(initialHeaderTableSize, cc.onNewHeaderField)
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go cc.readLoop()
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return cc, nil
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}
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func (cc *clientConn) setGoAway(f *GoAwayFrame) {
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cc.mu.Lock()
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defer cc.mu.Unlock()
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cc.goAway = f
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}
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func (cc *clientConn) canTakeNewRequest() bool {
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cc.mu.Lock()
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defer cc.mu.Unlock()
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return cc.goAway == nil &&
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int64(len(cc.streams)+1) < int64(cc.maxConcurrentStreams) &&
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cc.nextStreamID < 2147483647
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}
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func (cc *clientConn) closeIfIdle() {
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cc.mu.Lock()
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if len(cc.streams) > 0 {
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cc.mu.Unlock()
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return
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}
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cc.closed = true
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// TODO: do clients send GOAWAY too? maybe? Just Close:
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cc.mu.Unlock()
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cc.tconn.Close()
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}
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func (cc *clientConn) roundTrip(req *http.Request) (*http.Response, error) {
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cc.mu.Lock()
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if cc.closed {
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cc.mu.Unlock()
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return nil, errClientConnClosed
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}
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cs := cc.newStream()
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hasBody := false // TODO
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// we send: HEADERS[+CONTINUATION] + (DATA?)
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hdrs := cc.encodeHeaders(req)
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first := true
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for len(hdrs) > 0 {
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chunk := hdrs
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if len(chunk) > int(cc.maxFrameSize) {
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chunk = chunk[:cc.maxFrameSize]
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}
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hdrs = hdrs[len(chunk):]
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endHeaders := len(hdrs) == 0
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if first {
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cc.fr.WriteHeaders(HeadersFrameParam{
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StreamID: cs.ID,
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BlockFragment: chunk,
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EndStream: !hasBody,
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EndHeaders: endHeaders,
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})
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first = false
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} else {
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cc.fr.WriteContinuation(cs.ID, endHeaders, chunk)
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}
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}
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cc.bw.Flush()
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werr := cc.werr
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cc.mu.Unlock()
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if hasBody {
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// TODO: write data. and it should probably be interleaved:
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// go ... io.Copy(dataFrameWriter{cc, cs, ...}, req.Body) ... etc
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}
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if werr != nil {
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return nil, werr
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}
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re := <-cs.resc
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if re.err != nil {
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return nil, re.err
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}
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res := re.res
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res.Request = req
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res.TLS = cc.tlsState
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return res, nil
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}
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// requires cc.mu be held.
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func (cc *clientConn) encodeHeaders(req *http.Request) []byte {
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cc.hbuf.Reset()
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// TODO(bradfitz): figure out :authority-vs-Host stuff between http2 and Go
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host := req.Host
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if host == "" {
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host = req.URL.Host
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}
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path := req.URL.Path
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if path == "" {
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path = "/"
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}
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cc.writeHeader(":authority", host) // probably not right for all sites
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cc.writeHeader(":method", req.Method)
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cc.writeHeader(":path", path)
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cc.writeHeader(":scheme", "https")
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for k, vv := range req.Header {
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lowKey := strings.ToLower(k)
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if lowKey == "host" {
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continue
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}
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for _, v := range vv {
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cc.writeHeader(lowKey, v)
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}
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}
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return cc.hbuf.Bytes()
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}
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func (cc *clientConn) writeHeader(name, value string) {
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log.Printf("sending %q = %q", name, value)
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cc.henc.WriteField(hpack.HeaderField{Name: name, Value: value})
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}
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type resAndError struct {
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res *http.Response
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err error
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}
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// requires cc.mu be held.
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func (cc *clientConn) newStream() *clientStream {
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cs := &clientStream{
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ID: cc.nextStreamID,
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resc: make(chan resAndError, 1),
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}
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cc.nextStreamID += 2
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cc.streams[cs.ID] = cs
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return cs
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}
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func (cc *clientConn) streamByID(id uint32, andRemove bool) *clientStream {
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cc.mu.Lock()
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defer cc.mu.Unlock()
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cs := cc.streams[id]
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if andRemove {
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delete(cc.streams, id)
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}
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return cs
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}
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// runs in its own goroutine.
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func (cc *clientConn) readLoop() {
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defer cc.t.removeClientConn(cc)
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defer close(cc.readerDone)
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activeRes := map[uint32]*clientStream{} // keyed by streamID
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// Close any response bodies if the server closes prematurely.
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// TODO: also do this if we've written the headers but not
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// gotten a response yet.
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defer func() {
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err := cc.readerErr
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if err == io.EOF {
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err = io.ErrUnexpectedEOF
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}
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for _, cs := range activeRes {
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cs.pw.CloseWithError(err)
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}
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}()
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// continueStreamID is the stream ID we're waiting for
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// continuation frames for.
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var continueStreamID uint32
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for {
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f, err := cc.fr.ReadFrame()
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if err != nil {
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cc.readerErr = err
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return
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}
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log.Printf("Transport received %v: %#v", f.Header(), f)
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streamID := f.Header().StreamID
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_, isContinue := f.(*ContinuationFrame)
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if isContinue {
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if streamID != continueStreamID {
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log.Printf("Protocol violation: got CONTINUATION with id %d; want %d", streamID, continueStreamID)
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cc.readerErr = ConnectionError(ErrCodeProtocol)
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return
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}
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} else if continueStreamID != 0 {
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// Continue frames need to be adjacent in the stream
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// and we were in the middle of headers.
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log.Printf("Protocol violation: got %T for stream %d, want CONTINUATION for %d", f, streamID, continueStreamID)
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cc.readerErr = ConnectionError(ErrCodeProtocol)
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return
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}
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if streamID%2 == 0 {
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// Ignore streams pushed from the server for now.
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// These always have an even stream id.
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continue
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}
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streamEnded := false
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if ff, ok := f.(streamEnder); ok {
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streamEnded = ff.StreamEnded()
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}
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cs := cc.streamByID(streamID, streamEnded)
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if cs == nil {
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log.Printf("Received frame for untracked stream ID %d", streamID)
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continue
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}
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switch f := f.(type) {
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case *HeadersFrame:
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cc.nextRes = &http.Response{
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Proto: "HTTP/2.0",
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ProtoMajor: 2,
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Header: make(http.Header),
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}
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cs.pr, cs.pw = io.Pipe()
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cc.hdec.Write(f.HeaderBlockFragment())
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case *ContinuationFrame:
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cc.hdec.Write(f.HeaderBlockFragment())
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case *DataFrame:
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log.Printf("DATA: %q", f.Data())
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cs.pw.Write(f.Data())
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case *GoAwayFrame:
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cc.t.removeClientConn(cc)
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if f.ErrCode != 0 {
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// TODO: deal with GOAWAY more. particularly the error code
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log.Printf("transport got GOAWAY with error code = %v", f.ErrCode)
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}
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cc.setGoAway(f)
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default:
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log.Printf("Transport: unhandled response frame type %T", f)
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}
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headersEnded := false
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if he, ok := f.(headersEnder); ok {
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headersEnded = he.HeadersEnded()
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if headersEnded {
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continueStreamID = 0
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} else {
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continueStreamID = streamID
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}
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}
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if streamEnded {
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cs.pw.Close()
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delete(activeRes, streamID)
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}
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if headersEnded {
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if cs == nil {
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panic("couldn't find stream") // TODO be graceful
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}
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// TODO: set the Body to one which notes the
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// Close and also sends the server a
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// RST_STREAM
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cc.nextRes.Body = cs.pr
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res := cc.nextRes
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activeRes[streamID] = cs
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cs.resc <- resAndError{res: res}
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}
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}
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}
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func (cc *clientConn) onNewHeaderField(f hpack.HeaderField) {
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// TODO: verifiy pseudo headers come before non-pseudo headers
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// TODO: verifiy the status is set
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log.Printf("Header field: %+v", f)
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if f.Name == ":status" {
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code, err := strconv.Atoi(f.Value)
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if err != nil {
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panic("TODO: be graceful")
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}
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cc.nextRes.Status = f.Value + " " + http.StatusText(code)
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cc.nextRes.StatusCode = code
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return
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}
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if strings.HasPrefix(f.Name, ":") {
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// "Endpoints MUST NOT generate pseudo-header fields other than those defined in this document."
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// TODO: treat as invalid?
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return
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}
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cc.nextRes.Header.Add(http.CanonicalHeaderKey(f.Name), f.Value)
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}
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