add flags for disabling discovery and controlling logging

arp.go

@@ -37,7 +37,7 @@ func (t *Tendrils) readARPTable() {
 	entries := t.parseARPTable()
 
 	for _, entry := range entries {
-		if t.iface != "" && entry.iface != t.iface {
+		if t.Interface != "" && entry.iface != t.Interface {
 			continue
 		}
 		if isBroadcastOrZero(entry.mac) {

cmd/tendrils/main.go

@@ -7,9 +7,20 @@ import (
 )
 
 func main() {
-	iface := flag.String("i", "", "interface to use (default: all interfaces)")
+	iface := flag.String("i", "", "interface to use")
+	noARP := flag.Bool("no-arp", false, "disable ARP discovery")
+	noLLDP := flag.Bool("no-lldp", false, "disable LLDP discovery")
+	noSNMP := flag.Bool("no-snmp", false, "disable SNMP discovery")
+	logTree := flag.Bool("log-tree", false, "log full tree on changes")
+	logReasons := flag.Bool("log-reasons", false, "log addition reasons")
 	flag.Parse()
 
-	t := tendrils.New(*iface)
+	t := tendrils.New()
+	t.Interface = *iface
+	t.DisableARP = *noARP
+	t.DisableLLDP = *noLLDP
+	t.DisableSNMP = *noSNMP
+	t.LogTree = *logTree
+	t.LogReasons = *logReasons
 	t.Run()
 }

nodes.go

@@ -44,14 +44,16 @@ type Nodes struct {
 	ipIndex  map[string]int
 	macIndex map[string]int
 	nextID   int
+	t        *Tendrils
 }
 
-func NewNodes() *Nodes {
+func NewNodes(t *Tendrils) *Nodes {
 	n := &Nodes{
 		nodes:    map[int]*Node{},
 		ipIndex:  map[string]int{},
 		macIndex: map[string]int{},
 		nextID:   1,
+		t:        t,
 	}
 
 	n.nodes[0] = &Node{
@@ -122,11 +124,15 @@ func (n *Nodes) UpdateWithParent(parentIP net.IP, ips []net.IP, macs []net.Hardw
 			merging = append(merging, n.nodes[ids[i]].String())
 			n.mergeNodes(targetID, ids[i])
 		}
+		if n.t.LogReasons {
 			log.Printf("merged nodes %v into %s (via %s)", merging, n.nodes[targetID], source)
+		}
+		if n.t.LogTree {
 			n.mu.Unlock()
 			n.LogTree()
 			n.mu.Lock()
 		}
+	}
 
 	node := n.nodes[targetID]
 	var added []string
@@ -162,12 +168,16 @@ func (n *Nodes) UpdateWithParent(parentIP net.IP, ips []net.IP, macs []net.Hardw
 	}
 
 	if len(added) > 0 {
+		if n.t.LogReasons {
 			log.Printf("updated %s +%v (via %s)", node, added, source)
+		}
+		if n.t.LogTree {
 			n.mu.Unlock()
 			n.LogTree()
 			n.mu.Lock()
 		}
 	}
+}
 
 func (n *Nodes) mergeNodes(keepID, mergeID int) {
 	keep := n.nodes[keepID]

tendrils.go

@@ -11,15 +11,21 @@ import (
 type Tendrils struct {
 	activeInterfaces map[string]context.CancelFunc
 	nodes            *Nodes
-	iface            string
+
+	Interface   string
+	DisableARP  bool
+	DisableLLDP bool
+	DisableSNMP bool
+	LogTree     bool
+	LogReasons  bool
 }
 
-func New(iface string) *Tendrils {
+func New() *Tendrils {
-	return &Tendrils{
+	t := &Tendrils{
 		activeInterfaces: map[string]context.CancelFunc{},
-		nodes:            NewNodes(),
-		iface:            iface,
 	}
+	t.nodes = NewNodes(t)
+	return t
 }
 
 func (t *Tendrils) Run() {
@@ -28,8 +34,12 @@ func (t *Tendrils) Run() {
 
 	t.populateLocalAddresses()
 
+	if !t.DisableARP {
 		go t.pollARP(ctx)
+	}
+	if !t.DisableSNMP {
 		go t.pollSNMP(ctx)
+	}
 
 	ticker := time.NewTicker(1 * time.Second)
 	defer ticker.Stop()
@@ -90,7 +100,7 @@ func (t *Tendrils) listInterfaces() []net.Interface {
 
 	var validInterfaces []net.Interface
 	for _, iface := range interfaces {
-		if t.iface != "" && iface.Name != t.iface {
+		if t.Interface != "" && iface.Name != t.Interface {
 			continue
 		}
 		if iface.Flags&net.FlagUp == 0 {
@@ -145,5 +155,7 @@ func (t *Tendrils) updateInterfaces(interfaces []net.Interface) {
 }
 
 func (t *Tendrils) startInterface(ctx context.Context, iface net.Interface) {
+	if !t.DisableLLDP {
 		go t.listenLLDP(ctx, iface)
 	}
+}