From e0b46a8cff40e9a6d965a18900572c4832e1d075 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C5=99emysl=20Janouch?= <p@janouch.name>
Date: Wed, 1 Aug 2018 17:49:27 +0200
Subject: [PATCH] hid: figured out how to port timeouts

---
 hid/main.go | 84 ++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 64 insertions(+), 20 deletions(-)

diff --git a/hid/main.go b/hid/main.go
index bcf7bc6..c3b2875 100644
--- a/hid/main.go
+++ b/hid/main.go
@@ -761,7 +761,7 @@ var (
 
 	config         simpleConfig            // server configuration
 	serverName     string                  // our server name
-	pingInterval   uint                    // ping interval in seconds
+	pingInterval   time.Duration           // ping interval
 	maxConnections int                     // max connections allowed or 0
 	motd           []string                // MOTD (none if empty)
 	operators      = make(map[string]bool) // TLS cert. fingerprints for IRCops
@@ -773,7 +773,7 @@ var (
 	prepared = make(chan preparedEvent)
 	reads    = make(chan readEvent)
 	writes   = make(chan writeEvent)
-	timeouts = make(chan *client)
+	timers   = make(chan func())
 
 	tlsConf   *tls.Config
 	clients   = make(map[*client]bool)
@@ -962,12 +962,7 @@ func (c *client) kill(reason string) {
 		_ = c.transport.Close()
 	}
 
-	// Clean up the goroutine, although a spurious event may still be sent.
-	// TODO: Other timers if needed.
-	if c.killTimer != nil {
-		c.killTimer.Stop()
-	}
-
+	c.cancelTimers()
 	delete(clients, c)
 }
 
@@ -994,9 +989,7 @@ func (c *client) closeLink(reason string) {
 	c.closing = true
 
 	c.unregister(reason)
-	c.killTimer = time.AfterFunc(3*time.Second, func() {
-		timeouts <- c
-	})
+	c.setKillTimer()
 }
 
 func (c *client) inMaskList(masks []string) bool {
@@ -1025,7 +1018,57 @@ func (c *client) getTLSCertFingerprint() string {
 
 // --- Timers ------------------------------------------------------------------
 
-// TODO
+// Free the resources of timers that haven't fired yet and for timers that are
+// in between firing and being collected by the event loop, mark that the event
+// should not be acted upon.
+func (c *client) cancelTimers() {
+	for _, timer := range []**time.Timer{
+		&c.killTimer, &c.timeoutTimer, &c.pingTimer,
+	} {
+		if *timer != nil {
+			(*timer).Stop()
+			*timer = nil
+		}
+	}
+}
+
+// Arrange for a function to be called later from the main goroutine.
+func (c *client) setTimer(timer **time.Timer, delay time.Duration, cb func()) {
+	c.cancelTimers()
+
+	var identityCapture *time.Timer
+	identityCapture = time.AfterFunc(delay, func() {
+		timers <- func() {
+			// The timer might have been cancelled or even replaced.
+			// When the client is killed, this will be nil.
+			if *timer == identityCapture {
+				cb()
+			}
+		}
+	})
+
+	*timer = identityCapture
+}
+
+func (c *client) setKillTimer() {
+	c.setTimer(&c.killTimer, pingInterval, func() {
+		c.kill("Timeout")
+	})
+}
+
+func (c *client) setTimeoutTimer() {
+	c.setTimer(&c.timeoutTimer, pingInterval, func() {
+		c.closeLink(fmt.Sprintf("Ping timeout: >%d seconds",
+			pingInterval/time.Second))
+	})
+}
+
+func (c *client) setPingTimer() {
+	c.setTimer(&c.pingTimer, pingInterval, func() {
+		c.sendf("PING :%s", serverName)
+		c.setTimeoutTimer()
+	})
+}
 
 // --- IRC command handling ----------------------------------------------------
 
@@ -1451,7 +1494,7 @@ func ircHandlePONG(msg *message, c *client) {
 	}
 
 	// Set a new timer to send another PING
-	// TODO
+	c.setPingTimer()
 }
 
 func ircHandleQUIT(msg *message, c *client) {
@@ -2817,6 +2860,7 @@ func (c *client) onPrepared(host string, isTLS bool) {
 	// If we tried to send any data before now, we would need to flushSendQ.
 	go read(c)
 	c.reading = true
+	c.setPingTimer()
 }
 
 // Handle the results from trying to read from the client connection.
@@ -2996,6 +3040,9 @@ func processOneEvent() {
 	case <-quitTimer:
 		forceQuit("timeout")
 
+	case callback := <-timers:
+		callback()
+
 	case conn := <-conns:
 		if maxConnections > 0 && len(clients) >= maxConnections {
 			log.Println("connection limit reached, refusing connection")
@@ -3026,6 +3073,9 @@ func processOneEvent() {
 		clients[c] = true
 		go prepare(c)
 
+		// The TLS autodetection in prepare needs to have a timeout.
+		c.setKillTimer()
+
 	case ev := <-prepared:
 		log.Println("client is ready:", ev.host)
 		if _, ok := clients[ev.client]; ok {
@@ -3043,12 +3093,6 @@ func processOneEvent() {
 		if _, ok := clients[ev.client]; ok {
 			ev.client.onWrite(ev.written, ev.err)
 		}
-
-	case c := <-timeouts:
-		if _, ok := clients[c]; ok {
-			log.Println("client timeouted")
-			c.kill("TODO")
-		}
 	}
 }
 
@@ -3147,7 +3191,7 @@ func ircParseConfig() error {
 		} else if u < 1 {
 			return "the value is out of range"
 		} else {
-			pingInterval = uint(u)
+			pingInterval = time.Second * time.Duration(u)
 		}
 		return ""
 	})