Support WebSocket connections

cmd/bgammon-server/client_websocket.go

@@ -0,0 +1,134 @@
+package main
+
+import (
+	"log"
+	"net"
+	"net/http"
+	"sync"
+	"time"
+
+	"code.rocket9labs.com/tslocum/bgammon"
+	"github.com/gobwas/ws"
+	"github.com/gobwas/ws/wsutil"
+)
+
+var _ bgammon.Client = &webSocketClient{}
+
+type webSocketClient struct {
+	conn       net.Conn
+	events     chan []byte
+	commands   chan<- []byte
+	terminated bool
+	wgEvents   sync.WaitGroup
+}
+
+func newWebSocketClient(r *http.Request, w http.ResponseWriter, commands chan<- []byte, events chan []byte) *webSocketClient {
+	conn, _, _, err := ws.UpgradeHTTP(r, w)
+	if err != nil {
+		return nil
+	}
+
+	c := &webSocketClient{
+		conn:     conn,
+		events:   events,
+		commands: commands,
+	}
+	return c
+}
+
+func (c *webSocketClient) HandleReadWrite() {
+	if c.terminated {
+		return
+	}
+
+	go c.writeEvents()
+	c.readCommands()
+}
+
+func (c *webSocketClient) Write(message []byte) {
+	if c.terminated {
+		return
+	}
+
+	c.wgEvents.Add(1)
+	c.events <- message
+}
+
+func (c *webSocketClient) readCommands() {
+	setTimeout := func() {
+		err := c.conn.SetReadDeadline(time.Now().Add(clientTimeout))
+		if err != nil {
+			c.Terminate(err.Error())
+			return
+		}
+	}
+
+	setTimeout()
+	for {
+		if c.terminated {
+			continue // TODO wait group
+		}
+
+		msg, op, err := wsutil.ReadClientData(c.conn)
+		if err != nil {
+			c.Terminate(err.Error())
+			return
+		} else if op != ws.OpText {
+			continue
+		}
+
+		buf := make([]byte, len(msg))
+		copy(buf, msg)
+		c.commands <- buf
+
+		log.Printf("<- %s", msg)
+		setTimeout()
+	}
+}
+
+func (c *webSocketClient) writeEvents() {
+	setTimeout := func() {
+		err := c.conn.SetWriteDeadline(time.Now().Add(clientTimeout))
+		if err != nil {
+			c.Terminate(err.Error())
+			return
+		}
+	}
+
+	var event []byte
+	for event = range c.events {
+		if c.terminated {
+			c.wgEvents.Done()
+			continue
+		}
+		setTimeout()
+
+		err := wsutil.WriteServerMessage(c.conn, ws.OpText, event)
+		if err != nil {
+			c.Terminate(err.Error())
+			c.wgEvents.Done()
+			continue
+		}
+
+		log.Printf("-> %s", event)
+		c.wgEvents.Done()
+	}
+}
+
+func (c *webSocketClient) Terminate(reason string) {
+	if c.terminated {
+		return
+	}
+	c.terminated = true
+	c.conn.Close()
+	go func() {
+		time.Sleep(5 * time.Second)
+		c.wgEvents.Wait()
+		close(c.events)
+		close(c.commands)
+	}()
+}
+
+func (c *webSocketClient) Terminated() bool {
+	return c.terminated
+}

cmd/bgammon-server/main.go

@@ -9,12 +9,20 @@ import (
 )
 
 func main() {
-	var tcpAddress string
-	var debug int
+	var (
+		tcpAddress string
+		wsAddress  string
+		debug      int
+	)
 	flag.StringVar(&tcpAddress, "tcp", "localhost:1337", "TCP listen address")
+	flag.StringVar(&wsAddress, "ws", "localhost:1338", "WebSocket listen address")
 	flag.IntVar(&debug, "debug", 0, "print debug information and serve pprof on specified port")
 	flag.Parse()
 
+	if tcpAddress == "" && wsAddress == "" {
+		log.Fatal("Error: A TCP and/or WebSocket listen address must be specified.")
+	}
+
 	if debug > 0 {
 		go func() {
 			log.Fatal(http.ListenAndServe(fmt.Sprintf("localhost:%d", debug), nil))
@@ -22,6 +30,11 @@ func main() {
 	}
 
 	s := newServer()
-	s.listen("tcp", tcpAddress)
+	if tcpAddress != "" {
+		s.listen("tcp", tcpAddress)
+	}
+	if wsAddress != "" {
+		s.listen("ws", wsAddress)
+	}
 	select {}
 }

cmd/bgammon-server/server.go

@@ -6,6 +6,7 @@ import (
 	"log"
 	"math/rand"
 	"net"
+	"net/http"
 	"regexp"
 	"strconv"
 	"strings"
@@ -50,7 +51,41 @@ func newServer() *server {
 	return s
 }
 
+func (s *server) handleWebSocket(w http.ResponseWriter, r *http.Request) {
+	const bufferSize = 8
+	commands := make(chan []byte, bufferSize)
+	events := make(chan []byte, bufferSize)
+
+	wsClient := newWebSocketClient(r, w, commands, events)
+	if wsClient == nil {
+		return
+	}
+
+	now := time.Now().Unix()
+
+	c := &serverClient{
+		id:         <-s.newClientIDs,
+		account:    -1,
+		connected:  now,
+		lastActive: now,
+		commands:   commands,
+		Client:     wsClient,
+	}
+	s.handleClient(c)
+}
+
+func (s *server) listenWebSocket(address string) {
+	log.Printf("Listening for WebSocket connections on %s...", address)
+	err := http.ListenAndServe(address, http.HandlerFunc(s.handleWebSocket))
+	log.Fatalf("failed to listen on %s: %s", address, err)
+}
+
 func (s *server) listen(network string, address string) {
+	if strings.ToLower(network) == "ws" {
+		go s.listenWebSocket(address)
+		return
+	}
+
 	log.Printf("Listening for %s connections on %s...", strings.ToUpper(network), address)
 	listener, err := net.Listen(network, address)
 	if err != nil {
@@ -128,6 +163,22 @@ func (s *server) handleTerminatedGames() {
 	}
 }
 
+func (s *server) handleClient(c *serverClient) {
+	s.addClient(c)
+
+	log.Printf("Client %s connected", c.label())
+
+	go s.handlePingClient(c)
+	go s.handleClientCommands(c)
+
+	c.HandleReadWrite()
+
+	// Remove client.
+	s.removeClient(c)
+
+	log.Printf("Client %s disconnected", c.label())
+}
+
 func (s *server) handleConnection(conn net.Conn) {
 	const bufferSize = 8
 	commands := make(chan []byte, bufferSize)
@@ -144,19 +195,7 @@ func (s *server) handleConnection(conn net.Conn) {
 		Client:     newSocketClient(conn, commands, events),
 	}
 	s.sendHello(c)
-	s.addClient(c)
-
-	log.Printf("Client %s connected", c.label())
-
-	go s.handlePingClient(c)
-	go s.handleClientCommands(c)
-
-	c.HandleReadWrite()
-
-	// Remove client.
-	s.removeClient(c)
-
-	log.Printf("Client %s disconnected", c.label())
+	s.handleClient(c)
 }
 
 func (s *server) handlePingClient(c *serverClient) {

go.mod

@@ -1,3 +1,11 @@
 module code.rocket9labs.com/tslocum/bgammon
 
 go 1.20
+
+require github.com/gobwas/ws v1.3.0
+
+require (
+	github.com/gobwas/httphead v0.1.0 // indirect
+	github.com/gobwas/pool v0.2.1 // indirect
+	golang.org/x/sys v0.12.0 // indirect
+)

go.sum

@@ -0,0 +1,9 @@
+github.com/gobwas/httphead v0.1.0 h1:exrUm0f4YX0L7EBwZHuCF4GDp8aJfVeBrlLQrs6NqWU=
+github.com/gobwas/httphead v0.1.0/go.mod h1:O/RXo79gxV8G+RqlR/otEwx4Q36zl9rqC5u12GKvMCM=
+github.com/gobwas/pool v0.2.1 h1:xfeeEhW7pwmX8nuLVlqbzVc7udMDrwetjEv+TZIz1og=
+github.com/gobwas/pool v0.2.1/go.mod h1:q8bcK0KcYlCgd9e7WYLm9LpyS+YeLd8JVDW6WezmKEw=
+github.com/gobwas/ws v1.3.0 h1:sbeU3Y4Qzlb+MOzIe6mQGf7QR4Hkv6ZD0qhGkBFL2O0=
+github.com/gobwas/ws v1.3.0/go.mod h1:hRKAFb8wOxFROYNsT1bqfWnhX+b5MFeJM9r2ZSwg/KY=
+golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.12.0 h1:CM0HF96J0hcLAwsHPJZjfdNzs0gftsLfgKt57wWHJ0o=
+golang.org/x/sys v0.12.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=