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websocket_handler.go
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websocket_handler.go
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package proxy
import (
"log"
"net/http"
"time"
"code.cloudfoundry.org/loggregator-release/src/metricemitter"
"github.com/gorilla/websocket"
)
type websocketHandler struct {
messages <-chan []byte
keepAlive time.Duration
egressMetric *metricemitter.Counter
}
func NewWebsocketHandler(
m <-chan []byte,
keepAlive time.Duration,
egressMetric *metricemitter.Counter,
) *websocketHandler {
return &websocketHandler{
messages: m,
keepAlive: keepAlive,
egressMetric: egressMetric,
}
}
func (h *websocketHandler) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
upgrader := websocket.Upgrader{
CheckOrigin: func(*http.Request) bool { return true },
}
ws, err := upgrader.Upgrade(rw, r, nil)
if err != nil {
log.Printf("websocket handler: Not a websocket handshake: %s", err)
return
}
defer ws.Close()
closeCode, closeMessage := h.runWebsocketUntilClosed(ws)
_ = ws.WriteControl(websocket.CloseMessage, websocket.FormatCloseMessage(closeCode, closeMessage), time.Time{})
}
func (h *websocketHandler) runWebsocketUntilClosed(ws *websocket.Conn) (closeCode int, closeMessage string) {
keepAliveExpired := make(chan struct{})
clientWentAway := make(chan struct{})
go func() {
for {
_, _, err := ws.ReadMessage()
if err != nil {
close(clientWentAway)
return
}
}
}()
go func() {
NewKeepAlive(ws, h.keepAlive).Run()
close(keepAliveExpired)
}()
closeCode = websocket.CloseNormalClosure
closeMessage = ""
for {
select {
case <-clientWentAway:
return
case <-keepAliveExpired:
closeCode = websocket.ClosePolicyViolation
closeMessage = "Client did not respond to ping before keep-alive timeout expired."
return
case message, ok := <-h.messages:
if !ok {
return
}
_ = ws.SetWriteDeadline(time.Now().Add(6 * time.Second))
err := ws.WriteMessage(websocket.BinaryMessage, message)
if err != nil {
return
}
h.egressMetric.Increment(1)
}
}
}