filter multicast macs

arp.go

@@ -0,0 +1,114 @@
+package tendrils
+
+import (
+	"bufio"
+	"context"
+	"log"
+	"net"
+	"os/exec"
+	"runtime"
+	"strings"
+	"time"
+)
+
+func (t *Tendrils) pollARP(ctx context.Context) {
+	ticker := time.NewTicker(30 * time.Second)
+	defer ticker.Stop()
+
+	t.readARPTable()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-ticker.C:
+			t.readARPTable()
+		}
+	}
+}
+
+type arpEntry struct {
+	ip    net.IP
+	mac   net.HardwareAddr
+	iface string
+}
+
+func (t *Tendrils) readARPTable() {
+	entries := t.parseARPTable()
+
+	for _, entry := range entries {
+		if isBroadcastOrZero(entry.mac) {
+			continue
+		}
+
+		t.nodes.Update([]net.IP{entry.ip}, []net.HardwareAddr{entry.mac}, entry.iface, "", "arp")
+	}
+}
+
+func (t *Tendrils) parseARPTable() []arpEntry {
+	if runtime.GOOS == "darwin" {
+		return t.parseARPDarwin()
+	}
+	return t.parseARPLinux()
+}
+
+func (t *Tendrils) parseARPDarwin() []arpEntry {
+	cmd := exec.Command("arp", "-a")
+	output, err := cmd.Output()
+	if err != nil {
+		return nil
+	}
+
+	var entries []arpEntry
+	scanner := bufio.NewScanner(strings.NewReader(string(output)))
+	for scanner.Scan() {
+		line := scanner.Text()
+		fields := strings.Fields(line)
+		if len(fields) < 6 {
+			continue
+		}
+
+		ipStr := strings.Trim(fields[1], "()")
+		ip := net.ParseIP(ipStr)
+		if ip == nil {
+			continue
+		}
+
+		macStr := fields[3]
+		if macStr == "(incomplete)" {
+			continue
+		}
+
+		macStr = normalizeMACAddress(macStr)
+		mac, err := net.ParseMAC(macStr)
+		if err != nil {
+			log.Printf("[arp] failed to parse MAC %q for IP %s: %v", macStr, ipStr, err)
+			continue
+		}
+
+		ifaceName := fields[5]
+
+		entries = append(entries, arpEntry{
+			ip:    ip,
+			mac:   mac,
+			iface: ifaceName,
+		})
+	}
+
+	return entries
+}
+
+func (t *Tendrils) parseARPLinux() []arpEntry {
+	var entries []arpEntry
+	return entries
+}
+
+func normalizeMACAddress(mac string) string {
+	parts := strings.Split(mac, ":")
+	for i, part := range parts {
+		if len(part) == 1 {
+			parts[i] = "0" + part
+		}
+	}
+	return strings.Join(parts, ":")
+}

go.mod

@@ -2,6 +2,9 @@ module github.com/gopatchy/tendrils
 
 go 1.24.4
 
-require github.com/google/gopacket v1.1.19
+require (
+	github.com/google/gopacket v1.1.19
+	github.com/mostlygeek/arp v0.0.0-20170424181311-541a2129847a
+)
 
 require golang.org/x/sys v0.0.0-20190412213103-97732733099d // indirect

go.sum

@@ -1,5 +1,7 @@
 github.com/google/gopacket v1.1.19 h1:ves8RnFZPGiFnTS0uPQStjwru6uO6h+nlr9j6fL7kF8=
 github.com/google/gopacket v1.1.19/go.mod h1:iJ8V8n6KS+z2U1A8pUwu8bW5SyEMkXJB8Yo/Vo+TKTo=
+github.com/mostlygeek/arp v0.0.0-20170424181311-541a2129847a h1:AfneHvfmYgUIcgdUrrDFklLdEzQAvG9AKRTe1x1mx/0=
+github.com/mostlygeek/arp v0.0.0-20170424181311-541a2129847a/go.mod h1:jZxafo9CAqaKFQE4zitrg5QNlA6CXUsjwXPlIppF3tk=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/lint v0.0.0-20200302205851-738671d3881b/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=

lldp.go

@@ -77,5 +77,17 @@ func isBroadcastOrZero(mac net.HardwareAddr) bool {
 		}
 	}
 
-	return allZero || allFF
+	if allZero || allFF {
+		return true
+	}
+
+	if mac[0] == 0x01 && mac[1] == 0x00 && mac[2] == 0x5e {
+		return true
+	}
+
+	if mac[0] == 0x33 && mac[1] == 0x33 {
+		return true
+	}
+
+	return false
 }

nodes.go

@@ -197,31 +197,96 @@ func (n *Nodes) logNode(id int, prefix string, isLast bool) {
 
 	if id == 0 {
 		log.Printf("[root] %s", node)
+		n.logChildrenByInterface(id, "")
 	} else {
 		connector := "├──"
 		if isLast {
 			connector = "└──"
 		}
 
-		if node.ParentPort != "" && node.LocalPort != "" {
+		childPort := node.LocalPort
-			log.Printf("%s%s %s -> %s on %s", prefix, connector, node.ParentPort, node.LocalPort, node)
+		if childPort == "" {
-		} else {
+			childPort = "??"
-			log.Printf("%s%s %s", prefix, connector, node)
 		}
-	}
 
-	children := n.getChildren(id)
+		log.Printf("%s%s %s on %s", prefix, connector, childPort, node)
-	for i, childID := range children {
+
-		childIsLast := i == len(children)-1
+		children := n.getChildren(id)
-		childPrefix := prefix
+		for i, childID := range children {
-		if id != 0 {
+			childIsLast := i == len(children)-1
+			childPrefix := prefix
 			if isLast {
 				childPrefix += "    "
 			} else {
 				childPrefix += "│   "
 			}
+			n.logNode(childID, childPrefix, childIsLast)
+		}
+	}
+}
+
+func (n *Nodes) logChildrenByInterface(parentID int, prefix string) {
+	children := n.getChildren(parentID)
+
+	byInterface := map[string][]int{}
+	for _, childID := range children {
+		child := n.nodes[childID]
+		iface := child.ParentPort
+		if iface == "" {
+			iface = "??"
+		}
+		byInterface[iface] = append(byInterface[iface], childID)
+	}
+
+	var interfaces []string
+	for iface := range byInterface {
+		interfaces = append(interfaces, iface)
+	}
+	sort.Strings(interfaces)
+
+	for i, iface := range interfaces {
+		isLastInterface := i == len(interfaces)-1
+		connector := "├──"
+		if isLastInterface {
+			connector = "└──"
+		}
+
+		log.Printf("%s%s %s", prefix, connector, iface)
+
+		nodes := byInterface[iface]
+		for j, nodeID := range nodes {
+			isLastNode := j == len(nodes)-1
+			nodeConnector := "├──"
+			if isLastNode {
+				nodeConnector = "└──"
+			}
+
+			nodePrefix := prefix
+			if isLastInterface {
+				nodePrefix += "    "
+			} else {
+				nodePrefix += "│   "
+			}
+
+			node := n.nodes[nodeID]
+			childPort := node.LocalPort
+			if childPort == "" {
+				childPort = "??"
+			}
+
+			log.Printf("%s%s %s on %s", nodePrefix, nodeConnector, childPort, node)
+
+			grandchildren := n.getChildren(nodeID)
+			if len(grandchildren) > 0 {
+				grandchildPrefix := nodePrefix
+				if isLastNode {
+					grandchildPrefix += "    "
+				} else {
+					grandchildPrefix += "│   "
+				}
+				n.logChildrenByInterface(nodeID, grandchildPrefix)
+			}
 		}
-		n.logNode(childID, childPrefix, childIsLast)
 	}
 }
 

tendrils.go

@@ -20,6 +20,11 @@ func New() *Tendrils {
 }
 
 func (t *Tendrils) Run() {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	go t.pollARP(ctx)
+
 	ticker := time.NewTicker(1 * time.Second)
 	defer ticker.Stop()