From 64f491fcba9276b382932a2efe602f4d48038f43 Mon Sep 17 00:00:00 2001
From: Josh Deprez <josh.deprez@gmail.com>
Date: Sat, 30 Mar 2024 14:24:16 +1100
Subject: [PATCH] Handle SIGINT, send RD

---
 aurp/transport.go | 11 +++++++++++
 main.go           | 13 ++++++++-----
 peer.go           |  6 ++++++
 3 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/aurp/transport.go b/aurp/transport.go
index 70a57e2..221d6d4 100644
--- a/aurp/transport.go
+++ b/aurp/transport.go
@@ -111,6 +111,17 @@ func (tr *Transport) NewOpenRspPacket(envFlags RoutingFlag, rateOrErr int16, opt
 	}
 }
 
+func (tr *Transport) NewRDPacket(errCode ErrorCode) *RDPacket {
+	return &RDPacket{
+		Header: Header{
+			TrHeader:    tr.transaction(tr.LocalConnID),
+			CommandCode: CmdCodeRD,
+			Flags:       0,
+		},
+		ErrorCode: errCode,
+	}
+}
+
 func (tr *Transport) NewTicklePacket() *TicklePacket {
 	return &TicklePacket{
 		Header: Header{
diff --git a/main.go b/main.go
index 6e7f3fe..89db23c 100644
--- a/main.go
+++ b/main.go
@@ -5,6 +5,8 @@ import (
 	"flag"
 	"log"
 	"net"
+	"os"
+	"os/signal"
 	"regexp"
 
 	"gitea.drjosh.dev/josh/jrouter/aurp"
@@ -18,8 +20,6 @@ func main() {
 	flag.Parse()
 	log.Println("jrouter")
 
-	ctx := context.Background()
-
 	cfg, err := loadConfig(*configFilePath)
 	if err != nil {
 		log.Fatalf("Couldn't load configuration file: %v", err)
@@ -62,6 +62,9 @@ func main() {
 	defer ln.Close()
 	log.Printf("Listening on %v", ln.LocalAddr())
 
+	log.Println("Press ^C or send SIGINT to stop the router gracefully")
+	ctx, _ := signal.NotifyContext(context.Background(), os.Interrupt)
+
 	for _, peerStr := range cfg.Peers {
 		if !hasPortRE.MatchString(peerStr) {
 			peerStr += ":387"
@@ -92,15 +95,15 @@ func main() {
 	}
 
 	// Incoming packet loop
-	pb := make([]byte, 65536)
 	for {
-		pktlen, raddr, readErr := ln.ReadFromUDP(pb)
+		pktbuf := make([]byte, 65536)
+		pktlen, raddr, readErr := ln.ReadFromUDP(pktbuf)
 		// net.PacketConn.ReadFrom: "Callers should always process
 		// the n > 0 bytes returned before considering the error err."
 
 		log.Printf("Received packet of length %d from %v", pktlen, raddr)
 
-		dh, pkt, parseErr := aurp.ParsePacket(pb[:pktlen])
+		dh, pkt, parseErr := aurp.ParsePacket(pktbuf[:pktlen])
 		if parseErr != nil {
 			log.Printf("Failed to parse packet: %v", parseErr)
 			continue
diff --git a/peer.go b/peer.go
index 51aafe5..538cba9 100644
--- a/peer.go
+++ b/peer.go
@@ -32,6 +32,8 @@ func (p *peer) handle(ctx context.Context) error {
 	ticker := time.NewTicker(1 * time.Second)
 	defer ticker.Stop()
 
+	p.lastHeardFrom = time.Now()
+
 	// Write an Open-Req packet
 	n, err := p.send(p.tr.NewOpenReqPacket(nil))
 	if err != nil {
@@ -43,6 +45,10 @@ func (p *peer) handle(ctx context.Context) error {
 	for {
 		select {
 		case <-ctx.Done():
+			// Send a best-effort Router Down before returning
+			if _, err := p.send(p.tr.NewRDPacket(aurp.ErrCodeNormalClose)); err != nil {
+				log.Printf("Couldn't send RD packet: %v", err)
+			}
 			return ctx.Err()
 
 		case <-ticker.C: