From 75bbf4b0a4953b49bef45c0ddcc04a6271e83117 Mon Sep 17 00:00:00 2001
From: Ian Gulliver <github@flamingcow.io>
Date: Sat, 29 Nov 2025 22:13:25 -0800
Subject: [PATCH] fix local address population and snmp reverse port discovery
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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populate root node with local macs/ips at startup, excluding loopback addresses and permanent arp entries. detect when snmp finds parent node mac in child forwarding table and set child localport.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
---
 arp.go      |  5 +++++
 nodes.go    | 16 +++++++++-------
 snmp.go     | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 tendrils.go | 37 +++++++++++++++++++++++++++++++++++++
 4 files changed, 99 insertions(+), 7 deletions(-)

diff --git a/arp.go b/arp.go
index f1a5d0c..9736c09 100644
--- a/arp.go
+++ b/arp.go
@@ -63,6 +63,11 @@ func (t *Tendrils) parseARPDarwin() []arpEntry {
 	scanner := bufio.NewScanner(strings.NewReader(string(output)))
 	for scanner.Scan() {
 		line := scanner.Text()
+
+		if strings.Contains(line, "permanent") {
+			continue
+		}
+
 		fields := strings.Fields(line)
 		if len(fields) < 6 {
 			continue
diff --git a/nodes.go b/nodes.go
index 7aaeed7..3c10a95 100644
--- a/nodes.go
+++ b/nodes.go
@@ -122,14 +122,16 @@ func (n *Nodes) UpdateWithParent(parentIP net.IP, ips []net.IP, macs []net.Hardw
 	node := n.nodes[targetID]
 	var added []string
 
-	if node.LocalPort == "" && childPort != "" {
-		node.LocalPort = childPort
-		added = append(added, "localPort="+childPort)
-	}
+	if targetID != 0 {
+		if node.LocalPort == "" && childPort != "" {
+			node.LocalPort = childPort
+			added = append(added, "localPort="+childPort)
+		}
 
-	if node.ParentPort == "" && parentPort != "" {
-		node.ParentPort = parentPort
-		added = append(added, "parentPort="+parentPort)
+		if node.ParentPort == "" && parentPort != "" {
+			node.ParentPort = parentPort
+			added = append(added, "parentPort="+parentPort)
+		}
 	}
 
 	for _, ip := range ips {
diff --git a/snmp.go b/snmp.go
index d098cc1..6d5321a 100644
--- a/snmp.go
+++ b/snmp.go
@@ -207,6 +207,30 @@ func (t *Tendrils) queryBridgeMIB(snmp *gosnmp.GoSNMP, deviceIP net.IP) {
 		if addToParent {
 			t.nodes.Update([]net.IP{deviceIP}, []net.HardwareAddr{mac}, "", "", "snmp")
 		} else {
+			t.nodes.mu.RLock()
+			deviceNodeID := -1
+			if id, exists := t.nodes.ipIndex[deviceIP.String()]; exists {
+				deviceNodeID = id
+			}
+			macNodeID := -1
+			if id, exists := t.nodes.macIndex[mac.String()]; exists {
+				macNodeID = id
+			}
+
+			if deviceNodeID != -1 && macNodeID != -1 {
+				deviceNode := t.nodes.nodes[deviceNodeID]
+				if deviceNode.ParentID == macNodeID {
+					t.nodes.mu.RUnlock()
+					t.nodes.mu.Lock()
+					if deviceNode.LocalPort == "" {
+						deviceNode.LocalPort = ifName
+					}
+					t.nodes.mu.Unlock()
+					continue
+				}
+			}
+			t.nodes.mu.RUnlock()
+
 			t.nodes.UpdateWithParent(deviceIP, nil, []net.HardwareAddr{mac}, ifName, "", "snmp")
 		}
 	}
@@ -280,6 +304,30 @@ func (t *Tendrils) queryARPTable(snmp *gosnmp.GoSNMP, deviceIP net.IP) {
 				ifName = "??"
 			}
 
+			t.nodes.mu.RLock()
+			deviceNodeID := -1
+			if id, exists := t.nodes.ipIndex[deviceIP.String()]; exists {
+				deviceNodeID = id
+			}
+			macNodeID := -1
+			if id, exists := t.nodes.macIndex[mac.String()]; exists {
+				macNodeID = id
+			}
+
+			if deviceNodeID != -1 && macNodeID != -1 {
+				deviceNode := t.nodes.nodes[deviceNodeID]
+				if deviceNode.ParentID == macNodeID {
+					t.nodes.mu.RUnlock()
+					t.nodes.mu.Lock()
+					if deviceNode.LocalPort == "" {
+						deviceNode.LocalPort = ifName
+					}
+					t.nodes.mu.Unlock()
+					continue
+				}
+			}
+			t.nodes.mu.RUnlock()
+
 			t.nodes.UpdateWithParent(deviceIP, ips, []net.HardwareAddr{mac}, ifName, "", "snmp")
 		}
 	}
diff --git a/tendrils.go b/tendrils.go
index 4b40529..2c8fdfe 100644
--- a/tendrils.go
+++ b/tendrils.go
@@ -23,6 +23,8 @@ func (t *Tendrils) Run() {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
+	t.populateLocalAddresses()
+
 	go t.pollARP(ctx)
 	go t.pollSNMP(ctx)
 
@@ -36,6 +38,41 @@ func (t *Tendrils) Run() {
 	}
 }
 
+func (t *Tendrils) populateLocalAddresses() {
+	interfaces, err := net.Interfaces()
+	if err != nil {
+		return
+	}
+
+	t.nodes.mu.Lock()
+	defer t.nodes.mu.Unlock()
+
+	root := t.nodes.nodes[0]
+
+	for _, iface := range interfaces {
+		if len(iface.HardwareAddr) > 0 {
+			macKey := iface.HardwareAddr.String()
+			root.MACs[macKey] = iface.HardwareAddr
+			t.nodes.macIndex[macKey] = 0
+		}
+
+		addrs, err := iface.Addrs()
+		if err != nil {
+			continue
+		}
+
+		for _, addr := range addrs {
+			if ipnet, ok := addr.(*net.IPNet); ok {
+				if ipnet.IP.To4() != nil && !ipnet.IP.IsLoopback() {
+					ipKey := ipnet.IP.String()
+					root.IPs[ipKey] = ipnet.IP
+					t.nodes.ipIndex[ipKey] = 0
+				}
+			}
+		}
+	}
+}
+
 func (t *Tendrils) listInterfaces() []net.Interface {
 	interfaces, err := net.Interfaces()
 	if err != nil {