Fix interrupt group holding lock while closing connections

common/interrupt/conn.go

@@ -16,8 +16,8 @@ type Conn struct {
 
 func (c *Conn) Close() error {
 	c.group.access.Lock()
-	defer c.group.access.Unlock()
 	c.group.connections.Remove(c.element)
+	c.group.access.Unlock()
 	return c.Conn.Close()
 }
 
@@ -45,8 +45,8 @@ func newPacketConn(group *Group, conn net.PacketConn, element *list.Element[*gro
 
 func (c *PacketConn) Close() error {
 	c.group.access.Lock()
-	defer c.group.access.Unlock()
 	c.group.connections.Remove(c.element)
+	c.group.access.Unlock()
 	return c.NetPacketConn.Close()
 }
 

common/interrupt/group.go

@@ -38,15 +38,17 @@ func (g *Group) NewPacketConn(conn net.PacketConn, isExternal bool) net.PacketCo
 
 func (g *Group) Interrupt(interruptExternalConnections bool) {
 	g.access.Lock()
-	defer g.access.Unlock()
-	var toDelete []*list.Element[*groupConnItem]
-	for element := g.connections.Front(); element != nil; element = element.Next() {
+	var closers []io.Closer
+	for element := g.connections.Front(); element != nil; {
+		nextElement := element.Next()
 		if !element.Value.isExternal || interruptExternalConnections {
-			element.Value.conn.Close()
-			toDelete = append(toDelete, element)
+			closers = append(closers, element.Value.conn)
+			g.connections.Remove(element)
 		}
+		element = nextElement
 	}
-	for _, element := range toDelete {
-		g.connections.Remove(element)
+	g.access.Unlock()
+	for _, closer := range closers {
+		closer.Close()
 	}
 }