Fix coordinator locking

kylecarbs · kylecarbs · commit 79991a939139 · 2022-10-17T03:18:19.000Z
diff --git a/tailnet/coordinator.go b/tailnet/coordinator.go
@@ -246,7 +246,6 @@ func (c *coordinator) ServeAgent(conn net.Conn, id uuid.UUID) error {
 	}
 
 	sockets, ok := c.agentToConnectionSockets[id]
-	c.mutex.Unlock()
 	if ok {
 		// Publish all nodes that want to connect to the
 		// desired agent ID.
@@ -258,21 +257,21 @@ func (c *coordinator) ServeAgent(conn net.Conn, id uuid.UUID) error {
 			}
 			nodes = append(nodes, node)
 		}
+		c.mutex.Unlock()
 		data, err := json.Marshal(nodes)
 		if err != nil {
-			c.mutex.Unlock()
 			return xerrors.Errorf("marshal json: %w", err)
 		}
 		_, err = conn.Write(data)
 		if err != nil {
 			return xerrors.Errorf("write nodes: %w", err)
 		}
+		c.mutex.Lock()
 	}
 
 	// If an old agent socket is connected, we close it
 	// to avoid any leaks. This shouldn't ever occur because
 	// we expect one agent to be running.
-	c.mutex.Lock()
 	oldAgentSocket, ok := c.agentSockets[id]
 	if ok {
 		_ = oldAgentSocket.Close()

Original file line number	Diff line number	Diff line change
`@@ -246,7 +246,6 @@ func (c *coordinator) ServeAgent(conn net.Conn, id uuid.UUID) error {`
`246`	`246`	`}`
`247`	`247`
`248`	`248`	`sockets, ok := c.agentToConnectionSockets[id]`
`249`		`- c.mutex.Unlock()`
`250`	`249`	`if ok {`
`251`	`250`	`// Publish all nodes that want to connect to the`
`252`	`251`	`// desired agent ID.`
`@@ -258,21 +257,21 @@ func (c *coordinator) ServeAgent(conn net.Conn, id uuid.UUID) error {`
`258`	`257`	`}`
`259`	`258`	`nodes = append(nodes, node)`
`260`	`259`	`}`
	`260`	`+ c.mutex.Unlock()`
`261`	`261`	`data, err := json.Marshal(nodes)`
`262`	`262`	`if err != nil {`
`263`		`- c.mutex.Unlock()`
`264`	`263`	`return xerrors.Errorf("marshal json: %w", err)`
`265`	`264`	`}`
`266`	`265`	`_, err = conn.Write(data)`
`267`	`266`	`if err != nil {`
`268`	`267`	`return xerrors.Errorf("write nodes: %w", err)`
`269`	`268`	`}`
	`269`	`+ c.mutex.Lock()`
`270`	`270`	`}`
`271`	`271`
`272`	`272`	`// If an old agent socket is connected, we close it`
`273`	`273`	`// to avoid any leaks. This shouldn't ever occur because`
`274`	`274`	`// we expect one agent to be running.`
`275`		`- c.mutex.Lock()`
`276`	`275`	`oldAgentSocket, ok := c.agentSockets[id]`
`277`	`276`	`if ok {`
`278`	`277`	`_ = oldAgentSocket.Close()`