From cc2ce39170fd8c5e7dbd5bd011a75282387824d2 Mon Sep 17 00:00:00 2001
From: Wasabules <39313803+Wasabules@users.noreply.github.com>
Date: Sun, 12 Jul 2026 23:50:46 +0200
Subject: [PATCH] fix(server): avoid nil-channel deadlock and data race in Stop
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The worker goroutines ran `for fn := range s.workCh`, reading the shared
field on start-up. Stop() sets s.workCh to nil (before closing the locally
captured channel), so a worker that evaluated the range after that write
would range over a nil channel and block forever — wg.Wait() in Stop then
never returned, hanging shutdown. The same unsynchronised read also raced
with Stop's write, which `go test -race` flagged.

Capture the channel under the lock in Start and range over that local in
each worker, so the workers never touch s.workCh. submitWork already reads
s.workCh under RLock with a nil guard, so message posting is unaffected.

Pre-existing issue surfaced by the Start+Stop test added in #4. Verified
with `go test -race ./...` (all packages pass).
---
 internal/syslog/server.go | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/internal/syslog/server.go b/internal/syslog/server.go
index 99f629f..18b3fc8 100644
--- a/internal/syslog/server.go
+++ b/internal/syslog/server.go
@@ -129,6 +129,13 @@ func (s *SyslogServer) Start(config models.ServerConfig) error {
 	s.cancel = cancel
 	s.running = true
 	s.workCh = make(chan func(), maxWorkers*4)
+	// Capture the worker channel under the lock. The workers must range over
+	// this local, never s.workCh directly: Stop() sets s.workCh to nil, and a
+	// worker that evaluated `range s.workCh` after that write would range over
+	// a nil channel and block forever, deadlocking shutdown (wg.Wait never
+	// returns). Reading the shared field from the workers would also race with
+	// Stop's write.
+	workCh := s.workCh
 	s.connSem = make(chan struct{}, maxTCPConnections)
 	s.conns = make(map[net.Conn]struct{})
 
@@ -147,7 +154,7 @@ func (s *SyslogServer) Start(config models.ServerConfig) error {
 		s.wg.Add(1)
 		go func() {
 			defer s.wg.Done()
-			for fn := range s.workCh {
+			for fn := range workCh {
 				fn()
 			}
 		}()