From 5e9004c4076420ed3ecf706200084bbb044d4d33 Mon Sep 17 00:00:00 2001
From: Juan Font Alonso <juanfontalonso@gmail.com>
Date: Mon, 20 Jun 2022 21:40:28 +0200
Subject: [PATCH] Fix issues in the poll loop

---
 poll.go | 77 ++++++++++++++++++++++++++++++---------------------------
 1 file changed, 41 insertions(+), 36 deletions(-)

diff --git a/poll.go b/poll.go
index af7edab..195a261 100644
--- a/poll.go
+++ b/poll.go
@@ -293,17 +293,17 @@ func (h *Headscale) PollNetMapStream(
 		machine,
 	)
 
+	log.Trace().
+		Str("handler", "PollNetMapStream").
+		Str("machine", machine.Hostname).
+		Msg("Waiting for data to stream...")
+
+	log.Trace().
+		Str("handler", "PollNetMapStream").
+		Str("machine", machine.Hostname).
+		Msgf("pollData is %#v, keepAliveChan is %#v, updateChan is %#v", pollDataChan, keepAliveChan, updateChan)
+
 	for {
-		log.Trace().
-			Str("handler", "PollNetMapStream").
-			Str("machine", machine.Hostname).
-			Msg("Waiting for data to stream...")
-
-		log.Trace().
-			Str("handler", "PollNetMapStream").
-			Str("machine", machine.Hostname).
-			Msgf("pollData is %#v, keepAliveChan is %#v, updateChan is %#v", pollDataChan, keepAliveChan, updateChan)
-
 		select {
 		case data := <-pollDataChan:
 			log.Trace().
@@ -321,8 +321,9 @@ func (h *Headscale) PollNetMapStream(
 					Err(err).
 					Msg("Cannot write data")
 
-				break
+				return
 			}
+
 			log.Trace().
 				Str("handler", "PollNetMapStream").
 				Str("machine", machine.Hostname).
@@ -343,7 +344,7 @@ func (h *Headscale) PollNetMapStream(
 
 				// client has been removed from database
 				// since the stream opened, terminate connection.
-				break
+				return
 			}
 			now := time.Now().UTC()
 			machine.LastSeen = &now
@@ -360,16 +361,16 @@ func (h *Headscale) PollNetMapStream(
 					Str("channel", "pollData").
 					Err(err).
 					Msg("Cannot update machine LastSuccessfulUpdate")
-			} else {
-				log.Trace().
-					Str("handler", "PollNetMapStream").
-					Str("machine", machine.Hostname).
-					Str("channel", "pollData").
-					Int("bytes", len(data)).
-					Msg("Machine entry in database updated successfully after sending pollData")
+
+				return
 			}
 
-			break
+			log.Trace().
+				Str("handler", "PollNetMapStream").
+				Str("machine", machine.Hostname).
+				Str("channel", "pollData").
+				Int("bytes", len(data)).
+				Msg("Machine entry in database updated successfully after sending data")
 
 		case data := <-keepAliveChan:
 			log.Trace().
@@ -387,8 +388,9 @@ func (h *Headscale) PollNetMapStream(
 					Err(err).
 					Msg("Cannot write keep alive message")
 
-				break
+				return
 			}
+
 			log.Trace().
 				Str("handler", "PollNetMapStream").
 				Str("machine", machine.Hostname).
@@ -409,7 +411,7 @@ func (h *Headscale) PollNetMapStream(
 
 				// client has been removed from database
 				// since the stream opened, terminate connection.
-				break
+				return
 			}
 			now := time.Now().UTC()
 			machine.LastSeen = &now
@@ -421,16 +423,16 @@ func (h *Headscale) PollNetMapStream(
 					Str("channel", "keepAlive").
 					Err(err).
 					Msg("Cannot update machine LastSeen")
-			} else {
-				log.Trace().
-					Str("handler", "PollNetMapStream").
-					Str("machine", machine.Hostname).
-					Str("channel", "keepAlive").
-					Int("bytes", len(data)).
-					Msg("Machine updated successfully after sending keep alive")
+
+				return
 			}
 
-			break
+			log.Trace().
+				Str("handler", "PollNetMapStream").
+				Str("machine", machine.Hostname).
+				Str("channel", "keepAlive").
+				Int("bytes", len(data)).
+				Msg("Machine updated successfully after sending keep alive")
 
 		case <-updateChan:
 			log.Trace().
@@ -440,6 +442,7 @@ func (h *Headscale) PollNetMapStream(
 				Msg("Received a request for update")
 			updateRequestsReceivedOnChannel.WithLabelValues(machine.Namespace.Name, machine.Hostname).
 				Inc()
+
 			if h.isOutdated(machine) {
 				var lastUpdate time.Time
 				if machine.LastSuccessfulUpdate != nil {
@@ -459,6 +462,8 @@ func (h *Headscale) PollNetMapStream(
 						Str("channel", "update").
 						Err(err).
 						Msg("Could not get the map update")
+
+					return
 				}
 				_, err = w.Write(data)
 				if err != nil {
@@ -515,7 +520,10 @@ func (h *Headscale) PollNetMapStream(
 						Str("channel", "update").
 						Err(err).
 						Msg("Cannot update machine LastSuccessfulUpdate")
+
+					return
 				}
+
 			} else {
 				var lastUpdate time.Time
 				if machine.LastSuccessfulUpdate != nil {
@@ -529,8 +537,6 @@ func (h *Headscale) PollNetMapStream(
 					Msgf("%s is up to date", machine.Hostname)
 			}
 
-			return
-
 		case <-ctx.Done():
 			log.Info().
 				Str("handler", "PollNetMapStream").
@@ -550,7 +556,7 @@ func (h *Headscale) PollNetMapStream(
 
 				// client has been removed from database
 				// since the stream opened, terminate connection.
-				break
+				return
 			}
 			now := time.Now().UTC()
 			machine.LastSeen = &now
@@ -564,11 +570,10 @@ func (h *Headscale) PollNetMapStream(
 					Msg("Cannot update machine LastSeen")
 			}
 
-			break
+			// The connection has been closed, so we can stop polling.
+			return
 		}
 	}
-
-	log.Info().Msgf("Closing poll loop to %s", machine.Hostname)
 }
 
 func (h *Headscale) scheduledPollWorker(