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stream.go
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stream.go
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/*
Copyright 2015 The Kubernetes Authors All rights reserved.
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 wsstream
import (
"encoding/base64"
"io"
"net/http"
"time"
"golang.org/x/net/websocket"
"k8s.io/kubernetes/pkg/util"
)
// The WebSocket subprotocol "binary.k8s.io" will only send messages to the
// client and ignore messages sent to the server. The received messages are
// the exact bytes written to the stream. Zero byte messages are possible.
const binaryWebSocketProtocol = "binary.k8s.io"
// The WebSocket subprotocol "base64.binary.k8s.io" will only send messages to the
// client and ignore messages sent to the server. The received messages are
// a base64 version of the bytes written to the stream. Zero byte messages are
// possible.
const base64BinaryWebSocketProtocol = "base64.binary.k8s.io"
// Reader supports returning an arbitrary byte stream over a websocket channel.
// Supports the "binary.k8s.io" and "base64.binary.k8s.io" subprotocols.
type Reader struct {
err chan error
r io.Reader
ping bool
timeout time.Duration
}
// NewReader creates a WebSocket pipe that will copy the contents of r to a provided
// WebSocket connection. If ping is true, a zero length message will be sent to the client
// before the stream begins reading.
func NewReader(r io.Reader, ping bool) *Reader {
return &Reader{
r: r,
err: make(chan error),
ping: ping,
}
}
// SetIdleTimeout sets the interval for both reads and writes before timeout. If not specified,
// there is no timeout on the reader.
func (r *Reader) SetIdleTimeout(duration time.Duration) {
r.timeout = duration
}
func (r *Reader) handshake(config *websocket.Config, req *http.Request) error {
return handshake(config, req, []string{binaryWebSocketProtocol, base64BinaryWebSocketProtocol})
}
// Copy the reader to the response. The created WebSocket is closed after this
// method completes.
func (r *Reader) Copy(w http.ResponseWriter, req *http.Request) error {
go func() {
defer util.HandleCrash()
websocket.Server{Handshake: r.handshake, Handler: r.handle}.ServeHTTP(w, req)
}()
return <-r.err
}
// handle implements a WebSocket handler.
func (r *Reader) handle(ws *websocket.Conn) {
encode := len(ws.Config().Protocol) > 0 && ws.Config().Protocol[0] == base64BinaryWebSocketProtocol
defer close(r.err)
defer ws.Close()
go ignoreReceives(ws, r.timeout)
r.err <- messageCopy(ws, r.r, encode, r.ping, r.timeout)
}
func resetTimeout(ws *websocket.Conn, timeout time.Duration) {
if timeout > 0 {
ws.SetDeadline(time.Now().Add(timeout))
}
}
func messageCopy(ws *websocket.Conn, r io.Reader, base64Encode, ping bool, timeout time.Duration) error {
buf := make([]byte, 2048)
if ping {
resetTimeout(ws, timeout)
if err := websocket.Message.Send(ws, []byte{}); err != nil {
return err
}
}
for {
resetTimeout(ws, timeout)
n, err := r.Read(buf)
if err != nil {
if err == io.EOF {
return nil
}
return err
}
if n > 0 {
if base64Encode {
if err := websocket.Message.Send(ws, base64.StdEncoding.EncodeToString(buf[:n])); err != nil {
return err
}
} else {
if err := websocket.Message.Send(ws, buf[:n]); err != nil {
return err
}
}
}
}
}