begin implementing dns frontend

node/lux_dns.go

@@ -0,0 +1,63 @@
+package node
+
+import "net"
+
+type LuxDnsServer struct {
+	node     *LuxNode
+	stopChan chan bool
+}
+
+func NewLuxDnsServer(node *LuxNode) LuxDnsServer {
+	return LuxDnsServer{
+		node:     node,
+		stopChan: make(chan bool),
+	}
+}
+
+func (sv *LuxDnsServer) HandleRequest(req []byte) []byte {
+	return nil
+}
+
+func (sv *LuxDnsServer) CreateFrontend(udpListen string) error {
+	listenAddr, err := net.ResolveUDPAddr("udp", udpListen)
+	if err != nil {
+		return err
+	}
+
+	conn, err := net.ListenUDP("udp", listenAddr)
+	if err != nil {
+		return err
+	}
+
+	go func(sv *LuxDnsServer) {
+		defer conn.Close()
+
+		buf := make([]byte, 512)
+
+		for {
+			select {
+			case <-sv.stopChan:
+				return
+			default:
+				n, addr, err := conn.ReadFromUDP(buf)
+				if err != nil {
+					log.Debugf("failed to recv dns udp: %v\n", err)
+				}
+
+				res := sv.HandleRequest(buf[:n])
+				if len(res) > 0 {
+					_, err := conn.WriteToUDP(res, addr)
+					if err != nil {
+						log.Debugf("failed to send dns reply: %v\n", err)
+					}
+				}
+			}
+		}
+	}(sv)
+
+	return nil
+}
+
+func (sv *LuxDnsServer) Stop() {
+	sv.stopChan <- true
+}

node/lux_node.go

@@ -89,6 +89,20 @@ func (node *LuxNode) GetStateLock() *sync.RWMutex {
 	return &node.stateLock
 }
 
+func (node *LuxNode) GetHostByName(name string) (LuxHostState, bool) {
+	node.stateLock.RLock()
+	defer node.stateLock.RUnlock()
+
+	for _, host := range node.state.hosts {
+		if host.State.Hostname == name {
+			// explicitly make a copy to avoid concurrency problems
+			return *host, true
+		}
+	}
+
+	return LuxHostState{}, false
+}
+
 func (node *LuxNode) GetHostStateChannel() <-chan LuxHostState {
 	return node.state.GetStateChannel()
 }