From 1739b7fb875eb773f89e9f2c376d05ef87e5355f Mon Sep 17 00:00:00 2001
From: Ian Gulliver <github@flamingcow.io>
Date: Fri, 28 Nov 2025 15:18:22 -0800
Subject: [PATCH] Add network interface discovery and monitoring

---
 cmd/tendrils/main.go | 10 +++++
 go.mod               |  3 ++
 tendrils.go          | 93 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 106 insertions(+)
 create mode 100644 cmd/tendrils/main.go
 create mode 100644 go.mod
 create mode 100644 tendrils.go

diff --git a/cmd/tendrils/main.go b/cmd/tendrils/main.go
new file mode 100644
index 0000000..8d13302
--- /dev/null
+++ b/cmd/tendrils/main.go
@@ -0,0 +1,10 @@
+package main
+
+import (
+	"github.com/gopatchy/tendrils"
+)
+
+func main() {
+	t := tendrils.New()
+	t.Run()
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..13b8237
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module github.com/gopatchy/tendrils
+
+go 1.24.4
diff --git a/tendrils.go b/tendrils.go
new file mode 100644
index 0000000..545051e
--- /dev/null
+++ b/tendrils.go
@@ -0,0 +1,93 @@
+package tendrils
+
+import (
+	"context"
+	"log"
+	"net"
+	"time"
+)
+
+type Tendrils struct {
+	goroutines map[string]context.CancelFunc
+}
+
+func New() *Tendrils {
+	return &Tendrils{
+		goroutines: map[string]context.CancelFunc{},
+	}
+}
+
+func (t *Tendrils) Run() {
+	ticker := time.NewTicker(1 * time.Second)
+	defer ticker.Stop()
+
+	for {
+		interfaces := t.listInterfaces()
+		t.updateGoroutines(interfaces)
+		<-ticker.C
+	}
+}
+
+func (t *Tendrils) listInterfaces() []net.Interface {
+	interfaces, err := net.Interfaces()
+	if err != nil {
+		log.Printf("[ERROR] error getting interfaces: %v", err)
+		return nil
+	}
+
+	var validInterfaces []net.Interface
+	for _, iface := range interfaces {
+		if iface.Flags&net.FlagUp == 0 {
+			continue
+		}
+		if iface.Flags&net.FlagLoopback != 0 {
+			continue
+		}
+		if iface.Flags&net.FlagPointToPoint != 0 {
+			continue
+		}
+		if iface.Flags&net.FlagBroadcast == 0 {
+			continue
+		}
+		if len(iface.HardwareAddr) == 0 {
+			continue
+		}
+
+		addrs, err := iface.Addrs()
+		if err != nil || len(addrs) == 0 {
+			continue
+		}
+
+		validInterfaces = append(validInterfaces, iface)
+	}
+
+	return validInterfaces
+}
+
+func (t *Tendrils) updateGoroutines(interfaces []net.Interface) {
+	current := map[string]bool{}
+	for _, iface := range interfaces {
+		current[iface.Name] = true
+	}
+
+	for name, cancel := range t.goroutines {
+		if !current[name] {
+			log.Printf("interface removed: %s", name)
+			cancel()
+			delete(t.goroutines, name)
+		}
+	}
+
+	for _, iface := range interfaces {
+		if _, exists := t.goroutines[iface.Name]; !exists {
+			log.Printf("interface added: %s", iface.Name)
+			ctx, cancel := context.WithCancel(context.Background())
+			t.goroutines[iface.Name] = cancel
+			go t.handleInterface(ctx, iface)
+		}
+	}
+}
+
+func (t *Tendrils) handleInterface(ctx context.Context, iface net.Interface) {
+	<-ctx.Done()
+}