cloudflared-mirror/stream/stream.go

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package stream
import (
"encoding/hex"
"fmt"
"io"
"runtime/debug"
"sync/atomic"
"time"
"github.com/getsentry/raven-go"
"github.com/pkg/errors"
"github.com/rs/zerolog"
"github.com/cloudflare/cloudflared/cfio"
)
type bidirectionalStreamStatus struct {
doneChan chan struct{}
anyDone uint32
}
func newBiStreamStatus() *bidirectionalStreamStatus {
return &bidirectionalStreamStatus{
doneChan: make(chan struct{}, 2),
anyDone: 0,
}
}
func (s *bidirectionalStreamStatus) markUniStreamDone() {
atomic.StoreUint32(&s.anyDone, 1)
s.doneChan <- struct{}{}
}
func (s *bidirectionalStreamStatus) waitAnyDone() {
<-s.doneChan
}
func (s *bidirectionalStreamStatus) isAnyDone() bool {
return atomic.LoadUint32(&s.anyDone) > 0
}
// Pipe copies copy data to & from provided io.ReadWriters.
func Pipe(tunnelConn, originConn io.ReadWriter, log *zerolog.Logger) {
status := newBiStreamStatus()
go unidirectionalStream(tunnelConn, originConn, "origin->tunnel", status, log)
go unidirectionalStream(originConn, tunnelConn, "tunnel->origin", status, log)
// If one side is done, we are done.
status.waitAnyDone()
}
func unidirectionalStream(dst io.Writer, src io.Reader, dir string, status *bidirectionalStreamStatus, log *zerolog.Logger) {
defer func() {
// The bidirectional streaming spawns 2 goroutines to stream each direction.
// If any ends, the callstack returns, meaning the Tunnel request/stream (depending on http2 vs quic) will
// close. In such case, if the other direction did not stop (due to application level stopping, e.g., if a
// server/origin listens forever until closure), it may read/write from the underlying ReadWriter (backed by
// the Edge<->cloudflared transport) in an unexpected state.
// Because of this, we set this recover() logic.
if r := recover(); r != nil {
if status.isAnyDone() {
// We handle such unexpected errors only when we detect that one side of the streaming is done.
log.Debug().Msgf("Gracefully handled error %v in Streaming for %s, error %s", r, dir, debug.Stack())
} else {
// Otherwise, this is unexpected, but we prevent the program from crashing anyway.
log.Warn().Msgf("Gracefully handled unexpected error %v in Streaming for %s, error %s", r, dir, debug.Stack())
tags := make(map[string]string)
tags["root"] = "websocket.stream"
tags["dir"] = dir
switch rval := r.(type) {
case error:
raven.CaptureError(rval, tags)
default:
rvalStr := fmt.Sprint(rval)
raven.CaptureMessage(rvalStr, tags)
}
}
}
}()
_, err := copyData(dst, src, dir)
if err != nil {
log.Debug().Msgf("%s copy: %v", dir, err)
}
status.markUniStreamDone()
}
// when set to true, enables logging of content copied to/from origin and tunnel
const debugCopy = false
func copyData(dst io.Writer, src io.Reader, dir string) (written int64, err error) {
if debugCopy {
// copyBuffer is based on stdio Copy implementation but shows copied data
copyBuffer := func(dst io.Writer, src io.Reader, dir string) (written int64, err error) {
var buf []byte
size := 32 * 1024
buf = make([]byte, size)
for {
t := time.Now()
nr, er := src.Read(buf)
if nr > 0 {
fmt.Println(dir, t.UnixNano(), "\n"+hex.Dump(buf[0:nr]))
nw, ew := dst.Write(buf[0:nr])
if nw < 0 || nr < nw {
nw = 0
if ew == nil {
ew = errors.New("invalid write")
}
}
written += int64(nw)
if ew != nil {
err = ew
break
}
if nr != nw {
err = io.ErrShortWrite
break
}
}
if er != nil {
if er != io.EOF {
err = er
}
break
}
}
return written, err
}
return copyBuffer(dst, src, dir)
} else {
return cfio.Copy(dst, src)
}
}