Add broadcast pinging and fix node merging by shared IP

broadcast.go

@@ -0,0 +1,69 @@
+package tendrils
+
+import (
+	"context"
+	"log"
+	"net"
+	"time"
+
+	"golang.org/x/net/icmp"
+	"golang.org/x/net/ipv4"
+)
+
+func (t *Tendrils) pingBroadcast(ctx context.Context, iface net.Interface) {
+	_, broadcast := getInterfaceIPv4(iface)
+	if broadcast == nil {
+		return
+	}
+
+	t.sendBroadcastPing(broadcast, iface.Name)
+
+	ticker := time.NewTicker(30 * time.Second)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-ticker.C:
+			t.sendBroadcastPing(broadcast, iface.Name)
+		}
+	}
+}
+
+func (t *Tendrils) sendBroadcastPing(broadcast net.IP, ifaceName string) {
+	conn, err := icmp.ListenPacket("ip4:icmp", "0.0.0.0")
+	if err != nil {
+		if t.DebugARP {
+			log.Printf("[broadcast] %s: failed to create icmp socket: %v", ifaceName, err)
+		}
+		return
+	}
+	defer conn.Close()
+
+	msg := icmp.Message{
+		Type: ipv4.ICMPTypeEcho,
+		Code: 0,
+		Body: &icmp.Echo{
+			ID:   1,
+			Seq:  1,
+			Data: []byte("tendrils"),
+		},
+	}
+	msgBytes, err := msg.Marshal(nil)
+	if err != nil {
+		return
+	}
+
+	_, err = conn.WriteTo(msgBytes, &net.IPAddr{IP: broadcast})
+	if err != nil {
+		if t.DebugARP {
+			log.Printf("[broadcast] %s: failed to send ping to %s: %v", ifaceName, broadcast, err)
+		}
+		return
+	}
+
+	if t.DebugARP {
+		log.Printf("[broadcast] %s: sent ping to %s", ifaceName, broadcast)
+	}
+}

nodes.go

@@ -189,8 +189,16 @@ func (n *Nodes) updateNodeIPs(node *Node, nodeID int, ips []net.IP) []string {
 	var added []string
 	for _, ip := range ips {
 		ipKey := ip.String()
-		if _, exists := n.ipIndex[ipKey]; exists {
+		if existingID, exists := n.ipIndex[ipKey]; exists {
-			continue
+			if existingID == nodeID {
+				continue
+			}
+			if existingNode, nodeExists := n.nodes[existingID]; nodeExists {
+				n.mergeNodes(nodeID, existingID)
+				if n.t.LogEvents {
+					log.Printf("[merge] %s into %s (shared ip %s)", existingNode, node, ipKey)
+				}
+			}
 		}
 		n.ipIndex[ipKey] = nodeID
 		iface, exists := node.Interfaces[ipKey]
@@ -287,6 +295,14 @@ func (n *Nodes) updateNodeInterface(node *Node, nodeID int, mac net.HardwareAddr
 
 	for _, ip := range ips {
 		ipKey := ip.String()
+		if existingID, exists := n.ipIndex[ipKey]; exists && existingID != nodeID {
+			if existingNode, nodeExists := n.nodes[existingID]; nodeExists {
+				n.mergeNodes(nodeID, existingID)
+				if n.t.LogEvents {
+					log.Printf("[merge] %s into %s (shared ip %s)", existingNode, node, ipKey)
+				}
+			}
+		}
 		if !iface.IPs.Has(ipKey) {
 			added = append(added, "ip="+ipKey)
 		}

tendrils.go

@@ -223,6 +223,8 @@ func (t *Tendrils) updateInterfaces(interfaces []net.Interface) {
 }
 
 func (t *Tendrils) startInterface(ctx context.Context, iface net.Interface) {
+	go t.pingBroadcast(ctx, iface)
+
 	if !t.DisableLLDP {
 		go t.listenLLDP(ctx, iface)
 	}