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|
package channel
import (
"fmt"
"net/http"
"time"
"github.com/gorilla/websocket"
"gitlab.com/gitlab-org/labkit/log"
"gitlab.com/gitlab-org/gitlab-workhorse/internal/api"
"gitlab.com/gitlab-org/gitlab-workhorse/internal/helper"
)
var (
// See doc/channel.md for documentation of this subprotocol
subprotocols = []string{"terminal.gitlab.com", "base64.terminal.gitlab.com"}
upgrader = &websocket.Upgrader{Subprotocols: subprotocols}
ReauthenticationInterval = 5 * time.Minute
BrowserPingInterval = 30 * time.Second
)
func Handler(myAPI *api.API) http.Handler {
return myAPI.PreAuthorizeHandler(func(w http.ResponseWriter, r *http.Request, a *api.Response) {
if err := a.Channel.Validate(); err != nil {
helper.Fail500(w, r, err)
return
}
proxy := NewProxy(2) // two stoppers: auth checker, max time
checker := NewAuthChecker(
authCheckFunc(myAPI, r, "authorize"),
a.Channel,
proxy.StopCh,
)
defer checker.Close()
go checker.Loop(ReauthenticationInterval)
go closeAfterMaxTime(proxy, a.Channel.MaxSessionTime)
ProxyChannel(w, r, a.Channel, proxy)
}, "authorize")
}
func ProxyChannel(w http.ResponseWriter, r *http.Request, settings *api.ChannelSettings, proxy *Proxy) {
server, err := connectToServer(settings, r)
if err != nil {
helper.Fail500(w, r, err)
log.ContextLogger(r.Context()).WithError(err).Print("Channel: connecting to server failed")
return
}
defer server.UnderlyingConn().Close()
serverAddr := server.UnderlyingConn().RemoteAddr().String()
client, err := upgradeClient(w, r)
if err != nil {
log.ContextLogger(r.Context()).WithError(err).Print("Channel: upgrading client to websocket failed")
return
}
// Regularly send ping messages to the browser to keep the websocket from
// being timed out by intervening proxies.
go pingLoop(client)
defer client.UnderlyingConn().Close()
clientAddr := getClientAddr(r) // We can't know the port with confidence
logEntry := log.WithContextFields(r.Context(), log.Fields{
"clientAddr": clientAddr,
"serverAddr": serverAddr,
})
logEntry.Print("Channel: started proxying")
defer logEntry.Print("Channel: finished proxying")
if err := proxy.Serve(server, client, serverAddr, clientAddr); err != nil {
logEntry.WithError(err).Print("Channel: error proxying")
}
}
// In the future, we might want to look at X-Client-Ip or X-Forwarded-For
func getClientAddr(r *http.Request) string {
return r.RemoteAddr
}
func upgradeClient(w http.ResponseWriter, r *http.Request) (Connection, error) {
conn, err := upgrader.Upgrade(w, r, nil)
if err != nil {
return nil, err
}
return Wrap(conn, conn.Subprotocol()), nil
}
func pingLoop(conn Connection) {
for {
time.Sleep(BrowserPingInterval)
deadline := time.Now().Add(5 * time.Second)
if err := conn.WriteControl(websocket.PingMessage, nil, deadline); err != nil {
// Either the connection was already closed so no further pings are
// needed, or this connection is now dead and no further pings can
// be sent.
break
}
}
}
func connectToServer(settings *api.ChannelSettings, r *http.Request) (Connection, error) {
settings = settings.Clone()
helper.SetForwardedFor(&settings.Header, r)
conn, _, err := settings.Dial()
if err != nil {
return nil, err
}
return Wrap(conn, conn.Subprotocol()), nil
}
func closeAfterMaxTime(proxy *Proxy, maxSessionTime int) {
if maxSessionTime == 0 {
return
}
<-time.After(time.Duration(maxSessionTime) * time.Second)
proxy.StopCh <- fmt.Errorf(
"connection closed: session time greater than maximum time allowed - %v seconds",
maxSessionTime,
)
}
|
