CNPeer/Service refactor

- each CNPeer is given a unique chan *protocol.Event to pass events to
the service.handleEvents() loop. this is now passed to CNPeer.Handler()
as opposed to NewCNPeer().
- service has basically been rewritten. handleEvents() main loop uses
reflect.SelectCase() now to handle all of the eRecv channels for each
peer
- new protocol Event type: EVENT_CLIENT_CONNECT
- Added service_test.go; blackbox-styled testing like the others.
TestService() starts a service and spins up  a bunch of dummy peers
and verifies that each packet sent causes the corresponding packet
handler to be called.

internal/protocol/cnpeer.go

@@ -18,7 +18,6 @@ const (
 // CNPeer is a simple wrapper for net.Conn connections to send/recv packets over the Fusionfall packet protocol.
 type CNPeer struct {
 	conn     net.Conn
-	eRecv    chan *Event
 	whichKey int
 	alive    *atomic.Bool
 
@@ -33,10 +32,9 @@ func GetTime() uint64 {
 	return uint64(time.Now().UnixMilli())
 }
 
-func NewCNPeer(eRecv chan *Event, conn net.Conn) *CNPeer {
+func NewCNPeer(conn net.Conn) *CNPeer {
 	p := &CNPeer{
 		conn:     conn,
-		eRecv:    eRecv,
 		whichKey: USE_E,
 		alive:    &atomic.Bool{},
 
@@ -96,40 +94,41 @@ func (peer *CNPeer) SetActiveKey(whichKey int) {
 }
 
 func (peer *CNPeer) Kill() {
-	log.Printf("Killing peer %p", peer)
-
+	// de-bounce: only kill if alive
 	if !peer.alive.CompareAndSwap(true, false) {
 		return
 	}
 
+	log.Printf("Killing peer %p", peer)
 	peer.conn.Close()
-	peer.eRecv <- &Event{Type: EVENT_CLIENT_DISCONNECT, Peer: peer}
 }
 
 // meant to be invoked as a goroutine
-func (peer *CNPeer) Handler() {
-	defer peer.Kill()
+func (peer *CNPeer) Handler(eRecv chan<- *Event) error {
+	defer func() {
+		eRecv <- &Event{Type: EVENT_CLIENT_DISCONNECT, Peer: peer}
+		close(eRecv)
+		peer.Kill()
+	}()
 
 	peer.alive.Store(true)
+	eRecv <- &Event{Type: EVENT_CLIENT_CONNECT, Peer: peer}
 	for {
 		// read packet size, the goroutine spends most of it's time parked here
 		var sz uint32
 		if err := binary.Read(peer.conn, binary.LittleEndian, &sz); err != nil {
-			log.Printf("[FATAL] failed to read packet size! %v\n", err)
-			return
+			return err
 		}
 
 		// client should never send a packet size outside of this range
 		if sz > CN_PACKET_BUFFER_SIZE || sz < 4 {
-			log.Printf("[FATAL] malicious packet size received! %d", sz)
-			return
+			return fmt.Errorf("invalid packet size: %d", sz)
 		}
 
 		// grab buffer && read packet body
-		if err := func() error {
 		buf := GetBuffer()
 		if _, err := buf.ReadFrom(io.LimitReader(peer.conn, int64(sz))); err != nil {
-				return fmt.Errorf("failed to read packet body! %v", err)
+			return fmt.Errorf("failed to read packet body: %v", err)
 		}
 
 		// decrypt
@@ -143,12 +142,7 @@ func (peer *CNPeer) Handler() {
 		}
 
 		// dispatch packet
-			log.Printf("Got packet ID: %x, with a sizeof: %d\n", pktID, sz)
-			peer.eRecv <- &Event{Type: EVENT_CLIENT_PACKET, Peer: peer, Pkt: buf, PktID: pktID}
-			return nil
-		}(); err != nil {
-			log.Printf("[FATAL] %v", err)
-			return
-		}
+		// log.Printf("Got packet ID: %x, with a sizeof: %d\n", pktID, sz)
+		eRecv <- &Event{Type: EVENT_CLIENT_PACKET, Peer: peer, Pkt: buf, PktID: pktID}
 	}
 }

internal/protocol/event.go

@@ -4,6 +4,7 @@ import "bytes"
 
 const (
 	EVENT_CLIENT_DISCONNECT = iota
+	EVENT_CLIENT_CONNECT
 	EVENT_CLIENT_PACKET
 )
 

internal/service/service.go

@@ -1,9 +1,12 @@
 package service
 
 import (
+	"errors"
 	"fmt"
 	"log"
 	"net"
+	"reflect"
+	"strconv"
 	"sync"
 
 	"github.com/CPunch/gopenfusion/config"
@@ -20,9 +23,12 @@ type Service struct {
 	listener       net.Listener
 	port           int
 	Name           string
-	eRecv          chan *protocol.Event
+	stop           chan struct{} // tell active handleEvents() to stop
+	stopped        chan struct{}
+	started        chan struct{}
 	packetHandlers map[uint32]PacketHandler
-	peers          *sync.Map
+	peers          map[*protocol.CNPeer]interface{}
+	stateLock      sync.Mutex
 
 	// OnDisconnect is called when a peer disconnects from the service.
 	// uData is the stored value of the key/value pair in the peer map.
@@ -35,22 +41,34 @@ type Service struct {
 	OnConnect func(peer *protocol.CNPeer) (uData interface{})
 }
 
-func NewService(name string, port int) (*Service, error) {
-	listener, err := net.Listen("tcp", fmt.Sprintf(":%d", port))
+func RandomPort() (int, error) {
+	l, err := net.Listen("tcp", "127.0.0.1:0")
 	if err != nil {
-		return nil, err
+		return 0, err
 	}
+	defer l.Close()
 
-	service := &Service{
-		listener:       listener,
+	_, port, err := net.SplitHostPort(l.Addr().String())
+	if err != nil {
+		return 0, err
+	}
+	return strconv.Atoi(port)
+}
+
+func NewService(name string, port int) *Service {
+	srvc := &Service{
 		port: port,
 		Name: name,
-		eRecv:          make(chan *protocol.Event),
-		packetHandlers: make(map[uint32]PacketHandler),
-		peers:          &sync.Map{},
 	}
 
-	return service, nil
+	srvc.Reset()
+	return srvc
+}
+
+func (service *Service) Reset() {
+	service.packetHandlers = make(map[uint32]PacketHandler)
+	service.peers = make(map[*protocol.CNPeer]interface{})
+	service.started = make(chan struct{})
 }
 
 // may not be called while the service is running (eg. srvc.Start() has been called)
@@ -58,27 +76,151 @@ func (service *Service) AddPacketHandler(pktID uint32, handler PacketHandler) {
 	service.packetHandlers[pktID] = handler
 }
 
-func (service *Service) Start() {
-	log.Printf("%s service hosted on %s:%d\n", service.Name, config.GetAnnounceIP(), service.port)
+func (service *Service) Start() error {
+	service.stop = make(chan struct{})
+	service.stopped = make(chan struct{})
+	peerConnections := make(chan chan *protocol.Event)
+	go service.handleEvents(peerConnections)
 
-	go service.handleEvents()
+	// open listener socket
+	var err error
+	service.listener, err = net.Listen("tcp", fmt.Sprintf(":%d", service.port))
+	if err != nil {
+		return err
+	}
+
+	close(service.started) // signal that the service has started
+	log.Printf("%s service hosted on %s:%d\n", service.Name, config.GetAnnounceIP(), service.port)
 	for {
 		conn, err := service.listener.Accept()
 		if err != nil {
-			log.Println("Connection error: ", err)
-			return
+			fmt.Println(err)
+			// we expect this to happen when the service is stopped
+			if errors.Is(err, net.ErrClosed) {
+				return nil
+			}
+			return err
 		}
 
-		peer := protocol.NewCNPeer(service.eRecv, conn)
-		service.connect(peer)
+		// create a new peer and pass it to the event loop
+		eRecv := make(chan *protocol.Event)
+		peer := protocol.NewCNPeer(conn)
+		log.Printf("New peer %p connected to %s\n", peer, service.Name)
+		peerConnections <- eRecv
+		go peer.Handler(eRecv)
 	}
 }
 
-func (service *Service) handleEvents() {
-	for event := range service.eRecv {
+// returns a channel that is closed when the service has started.
+// this is useful if you need to do something after the service has started.
+func (service *Service) Started() <-chan struct{} {
+	return service.started
+}
+
+// returns a channel that is closed when the service has stopped.
+// this is useful if you need to wait until the service has completely stopped.
+func (service *Service) Stopped() <-chan struct{} {
+	return service.stopped
+}
+
+// stops the service and disconnects all peers. OnDisconnect will be called
+// for each peer.
+func (service *Service) Stop() {
+	close(service.stop)
+
+	service.listener.Close()
+}
+
+// returns the stored uData for the peer.
+// if the peer does not exist, nil is returned.
+// NOTE: the peer map is not locked while accessing, if you're calling this
+// outside of the service's event loop, you'll need to lock the peer map yourself.
+func (service *Service) GetPeerData(peer *protocol.CNPeer) interface{} {
+	return service.peers[peer]
+}
+
+// sets the stored uData for the peer.
+// NOTE: the peer map is not locked while accessing, if you're calling this
+// outside of the service's event loop, you'll need to lock the peer map yourself.
+func (service *Service) SetPeerData(peer *protocol.CNPeer, uData interface{}) {
+	service.peers[peer] = uData
+}
+
+// calls f for each peer in the service passing the peer and the stored uData.
+// if f returns false, the iteration is stopped.
+// NOTE: the peer map is not locked while iterating, if you're calling this
+// outside of the service's event loop, you'll need to lock the peer map yourself.
+func (service *Service) RangePeers(f func(peer *protocol.CNPeer, uData interface{}) bool) {
+	for peer, uData := range service.peers {
+		if !f(peer, uData) {
+			break
+		}
+	}
+}
+
+// locks the peer map.
+func (service *Service) Lock() {
+	service.stateLock.Lock()
+}
+
+// unlocks the peer map.
+func (service *Service) Unlock() {
+	service.stateLock.Unlock()
+}
+
+// handleEvents is the main event loop for the service.
+// it handles all events from the peers and calls the appropriate handlers.
+func (service *Service) handleEvents(eRecv <-chan chan *protocol.Event) {
+	poll := make([]reflect.SelectCase, 0, 4)
+
+	// add the stop channel and the peer connection channel to our poll queue
+	poll = append(poll, reflect.SelectCase{
+		Dir:  reflect.SelectRecv,
+		Chan: reflect.ValueOf(service.stop),
+	})
+	poll = append(poll, reflect.SelectCase{
+		Dir:  reflect.SelectRecv,
+		Chan: reflect.ValueOf(eRecv),
+	})
+
+	for {
+		chosen, value, _ := reflect.Select(poll)
+		if chosen == 0 {
+			// stop
+
+			// OnDisconnect handler might need to do something important
+			service.Lock()
+			service.RangePeers(func(peer *protocol.CNPeer, uData interface{}) bool {
+				peer.Kill()
+				service.disconnect(peer)
+				return true
+			})
+			service.Unlock()
+
+			// signal we have stopped
+			close(service.stopped)
+			return
+		} else if chosen == 1 {
+			// new peer, add it to our poll queue
+			poll = append(poll, reflect.SelectCase{
+				Dir:  reflect.SelectRecv,
+				Chan: reflect.ValueOf(value.Interface()),
+			})
+		} else {
+			// peer event
+			event, ok := value.Interface().(*protocol.Event)
+			if !ok {
+				panic("invalid event type")
+			}
+
+			service.Lock()
 			switch event.Type {
 			case protocol.EVENT_CLIENT_DISCONNECT:
-			service.disconnect(event.Peer)
+				// strip the peer from our poll queue
+				poll = append(poll[:chosen], poll[chosen+1:]...)
+				service.disconnect(value.Interface().(*protocol.Event).Peer)
+			case protocol.EVENT_CLIENT_CONNECT:
+				service.connect(event.Peer)
 			case protocol.EVENT_CLIENT_PACKET:
 				if err := service.handlePacket(event.Peer, event.PktID, protocol.NewPacket(event.Pkt)); err != nil {
 					log.Printf("Error handling packet: %v", err)
@@ -88,12 +230,15 @@ func (service *Service) handleEvents() {
 				// the packet buffer is given to us by the event, so we'll need to make sure to return it to the pool
 				protocol.PutBuffer(event.Pkt)
 			}
+			service.Unlock()
+		}
 	}
 }
 
 func (service *Service) handlePacket(peer *protocol.CNPeer, typeID uint32, pkt protocol.Packet) error {
-	uData, _ := service.peers.Load(peer)
+	uData := service.peers[peer]
 	if hndlr, ok := service.packetHandlers[typeID]; ok {
+		// fmt.Printf("Handling packet %x\n", typeID)
 		if err := hndlr(peer, uData, pkt); err != nil {
 			return err
 		}
@@ -106,12 +251,12 @@ func (service *Service) handlePacket(peer *protocol.CNPeer, typeID uint32, pkt p
 
 func (service *Service) disconnect(peer *protocol.CNPeer) {
 	if service.OnDisconnect != nil {
-		uData, _ := service.peers.Load(peer)
+		uData := service.peers[peer]
 		service.OnDisconnect(peer, uData)
 	}
 
 	log.Printf("Peer %p disconnected from %s\n", peer, service.Name)
-	service.peers.Delete(peer)
+	delete(service.peers, peer)
 }
 
 func (service *Service) connect(peer *protocol.CNPeer) {
@@ -123,16 +268,5 @@ func (service *Service) connect(peer *protocol.CNPeer) {
 	}
 
 	log.Printf("New peer %p connected to %s\n", peer, service.Name)
-	service.peers.Store(peer, uData)
-	go peer.Handler()
-}
-
-func (service *Service) SetPeerData(peer *protocol.CNPeer, uData interface{}) {
-	service.peers.Store(peer, uData)
-}
-
-func (service *Service) RangePeers(f func(peer *protocol.CNPeer, uData interface{}) bool) {
-	service.peers.Range(func(key, value any) bool {
-		return f(key.(*protocol.CNPeer), value)
-	})
+	service.SetPeerData(peer, uData)
 }

internal/service/service_test.go

@@ -0,0 +1,91 @@
+package service_test
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/CPunch/gopenfusion/internal/protocol"
+	"github.com/CPunch/gopenfusion/internal/service"
+)
+
+var (
+	srvc     *service.Service
+	srvcPort int
+)
+
+const (
+	timeout       = 5
+	maxDummyPeers = 5
+)
+
+func waitWithTimeout(wg *sync.WaitGroup, seconds int) bool {
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		wg.Wait()
+	}()
+
+	select {
+	case <-done:
+		return true
+	case <-time.After(time.Duration(seconds) * time.Second):
+		return false
+	}
+}
+
+func TestMain(m *testing.M) {
+	var err error
+	srvcPort, err = service.RandomPort()
+	if err != nil {
+		panic(err)
+	}
+
+	srvc = service.NewService("TEST", srvcPort)
+	os.Exit(m.Run())
+}
+
+func TestService(t *testing.T) {
+	// waitgroup to wait for test packet handler to be called
+	wg := sync.WaitGroup{}
+
+	srvc.AddPacketHandler(0x1234, func(peer *protocol.CNPeer, uData interface{}, pkt protocol.Packet) error {
+		wg.Done()
+		return nil
+	})
+
+	go func() {
+		if err := srvc.Start(); err != nil {
+			t.Error(err)
+		}
+	}()
+
+	// wait for service to start
+	<-srvc.Started()
+	wg.Add(maxDummyPeers)
+	for i := 0; i < maxDummyPeers; i++ {
+		go func() {
+			// make dummy client
+			conn, err := net.Dial("tcp", fmt.Sprintf("127.0.0.1:%d", srvcPort))
+			if err != nil {
+				t.Error(err)
+			}
+
+			peer := protocol.NewCNPeer(conn)
+			defer peer.Kill()
+			// send dummy packet
+			if err := peer.Send(0x1234); err != nil {
+				t.Error(err)
+			}
+		}()
+	}
+
+	if !waitWithTimeout(&wg, timeout) {
+		t.Error("timeout waiting for packet handler to be called")
+	}
+	srvc.Stop()
+	<-srvc.Stopped()
+}

login/loginserver.go

@@ -14,10 +14,7 @@ type LoginServer struct {
 }
 
 func NewLoginServer(dbHndlr *db.DBHandler, redisHndlr *redis.RedisHandler, port int) (*LoginServer, error) {
-	srvc, err := service.NewService("LOGIN", port)
-	if err != nil {
-		return nil, err
-	}
+	srvc := service.NewService("LOGIN", port)
 
 	server := &LoginServer{
 		service:    srvc,
@@ -47,6 +44,10 @@ func NewLoginServer(dbHndlr *db.DBHandler, redisHndlr *redis.RedisHandler, port
 	return server, nil
 }
 
-func (server *LoginServer) Start() {
-	server.service.Start()
+func (server *LoginServer) Start() error {
+	return server.service.Start()
+}
+
+func (server *LoginServer) Stop() {
+	server.service.Stop()
 }

shard/shardserver.go

@@ -19,10 +19,7 @@ type ShardServer struct {
 }
 
 func NewShardServer(dbHndlr *db.DBHandler, redisHndlr *redis.RedisHandler, port int) (*ShardServer, error) {
-	srvc, err := service.NewService("SHARD", port)
-	if err != nil {
-		return nil, err
-	}
+	srvc := service.NewService("SHARD", port)
 
 	server := &ShardServer{
 		service:    srvc,