Improving Mac discovery

internal/clientinfo/merlin.go

@@ -0,0 +1,67 @@
+package clientinfo
+
+import (
+	"strings"
+	"sync"
+
+	"github.com/Control-D-Inc/ctrld/internal/router"
+	"github.com/Control-D-Inc/ctrld/internal/router/merlin"
+
+	"github.com/Control-D-Inc/ctrld"
+	"github.com/Control-D-Inc/ctrld/internal/router/nvram"
+)
+
+const merlinNvramCustomClientListKey = "custom_clientlist"
+
+type merlinDiscover struct {
+	hostname sync.Map // mac => hostname
+}
+
+func (m *merlinDiscover) refresh() error {
+	if router.Name() != merlin.Name {
+		return nil
+	}
+	out, err := nvram.Run("get", merlinNvramCustomClientListKey)
+	if err != nil {
+		return err
+	}
+	ctrld.ProxyLog.Debug().Msg("reading Merlin custom client list")
+	m.parseMerlinCustomClientList(out)
+	return nil
+}
+
+func (m *merlinDiscover) LookupHostnameByIP(ip string) string {
+	return ""
+}
+
+func (m *merlinDiscover) LookupHostnameByMac(mac string) string {
+	val, ok := m.hostname.Load(mac)
+	if !ok {
+		return ""
+	}
+	return val.(string)
+}
+
+// "nvram get custom_clientlist" output:
+//
+// <client 1>00:00:00:00:00:01>0>4>><client 2>00:00:00:00:00:02>0>24>>...
+//
+// So to parse it, do the following steps:
+//
+//   - Split by "<"                 => entries
+//   - For each entry, split by ">" => parts
+//   - Empty parts                  => skip
+//   - Empty parts[0]               => skip empty hostname
+//   - Empty parts[1]               => skip empty MAC
+func (m *merlinDiscover) parseMerlinCustomClientList(data string) {
+	entries := strings.Split(data, "<")
+	for _, entry := range entries {
+		parts := strings.SplitN(string(entry), ">", 3)
+		if len(parts) < 2 || len(parts[0]) == 0 || len(parts[1]) == 0 {
+			continue
+		}
+		hostname := normalizeHostname(parts[0])
+		mac := strings.ToLower(parts[1])
+		m.hostname.Store(mac, hostname)
+	}
+}