cwtch/app/plugins/networkCheck.go

package plugins

import (
	"cwtch.im/cwtch/event"
	"git.openprivacy.ca/openprivacy/libricochet-go/connectivity"
	"git.openprivacy.ca/openprivacy/libricochet-go/log"
	"git.openprivacy.ca/openprivacy/libricochet-go/policies"
	"time"
)

// networkCheck is a convenience plugin for testing high level availability of onion services
type networkCheck struct {
	bus           event.Manager
	queue         event.Queue
	acn           connectivity.ACN
	onionsToCheck []string
	breakChan     chan bool
	running       bool
}

// NewNetworkCheck returns a Plugin that when started will attempt various network tests
func NewNetworkCheck(bus event.Manager, acn connectivity.ACN) Plugin {
	nc := &networkCheck{bus: bus, acn: acn, queue: event.NewQueue(), breakChan: make(chan bool, 1)}
	return nc
}

func (nc *networkCheck) Start() {
	go nc.run()
}

func (nc *networkCheck) run() {
	nc.running = true
	nc.bus.Subscribe(event.ProtocolEngineStartListen, nc.queue)
	nc.bus.Subscribe(event.NewMessageFromPeer, nc.queue)
	nc.bus.Subscribe(event.PeerAcknowledgement, nc.queue)
	nc.bus.Subscribe(event.EncryptedGroupMessage, nc.queue)
	var lastMessageReceived time.Time
	for {
		select {
		case <-nc.breakChan:
			nc.running = false
			return
		case e := <-nc.queue.OutChan():
			switch e.EventType {
			// On receipt of a Listen request for an onion service we will add the onion to our list
			// and then we will wait a minute and check the connection for the first time (the onion should be up)
			// under normal operating circumstances
			case event.ProtocolEngineStartListen:
				log.Debugf("initiating connection check for %v", e.Data[event.Onion])
				nc.onionsToCheck = append(nc.onionsToCheck, e.Data[event.Onion])
			default:
				// if we receive either an encrypted group message or a peer acknowledgement we can assume the network
				// is up and running (our onion service might still not be available, but we would aim to detect that
				// through other actions
				// we reset out timer
				lastMessageReceived = time.Now()
			}
		case <-time.After(tickTime):
			// if we haven't received an action in the last minute...kick off a set of testing
			if time.Now().Sub(lastMessageReceived) > time.Minute {
				for _, onion := range nc.onionsToCheck {
					go nc.checkConnection(onion)
				}
			}
		}
	}
}

func (nc *networkCheck) Shutdown() {
	if nc.running {
		nc.queue.Shutdown()
		log.Debugf("shutting down network status plugin")
		nc.breakChan <- true
	}
}

//
func (nc *networkCheck) checkConnection(onion string) {
	// we want to definitively time these actions out faster than tor will, because these onions should definitely be
	// online
	ClientTimeout := policies.TimeoutPolicy(time.Second * 60)
	err := ClientTimeout.ExecuteAction(func() error {
		conn, _, err := nc.acn.Open(onion)
		if err == nil {
			conn.Close()
		}
		return err
	})
	// regardless of the outcome we want to report a status to let anyone who might care know that we did do a check
	if err != nil {
		log.Debugf("publishing network error for %v", onion)
		nc.bus.Publish(event.NewEvent(event.NetworkStatus, map[event.Field]string{event.Onion: onion, event.Error: err.Error(), event.Status: "Error"}))
	} else {
		log.Debugf("publishing network success for %v", onion)
		nc.bus.Publish(event.NewEvent(event.NetworkStatus, map[event.Field]string{event.Onion: onion, event.Error: "", event.Status: "Success"}))
	}
}