Refactor increments, rando connID

aurp/aurp.go

@@ -101,6 +101,14 @@ type Packet interface {
 	io.WriterTo
 }
 
+// Inc increments a uint16. It avoids 0 (65535 + 1 = 1).
+func Inc(p *uint16) {
+	*p++
+	if *p == 0 {
+		*p++
+	}
+}
+
 // ParsePacket parses the body of a UDP packet for a domain header, and then
 // based on the packet type, an AURP-Tr header, an AURP routing header, and
 // then a particular packet type.

aurp/transport.go

@@ -69,20 +69,6 @@ type Transport struct {
 	LocalSeq, RemoteSeq uint16
 }
 
-func (tr *Transport) IncLocalSeq() {
-	tr.LocalSeq++
-	if tr.LocalSeq == 0 {
-		tr.LocalSeq = 1
-	}
-}
-
-func (tr *Transport) IncRemoteSeq() {
-	tr.RemoteSeq++
-	if tr.RemoteSeq == 0 {
-		tr.RemoteSeq = 1
-	}
-}
-
 // domainHeader returns a new domain header suitable for sending a packet.
 func (tr *Transport) domainHeader(pt PacketType) DomainHeader {
 	return DomainHeader{

main.go

@@ -21,6 +21,7 @@ import (
 	"errors"
 	"flag"
 	"log"
+	"math/rand/v2"
 	"net"
 	"os"
 	"os/signal"
@@ -74,7 +75,10 @@ func main() {
 	log.Printf("EtherTalk configuration: %+v", cfg.EtherTalk)
 
 	peers := make(map[udpAddr]*peer)
-	nextConnID := uint16(1)
+	var nextConnID uint16
+	for nextConnID == 0 {
+		nextConnID = uint16(rand.IntN(0x10000))
+	}
 
 	ln, err := net.ListenUDP("udp4", &net.UDPAddr{Port: int(cfg.ListenPort)})
 	if err != nil {
@@ -124,9 +128,9 @@ func main() {
 			raddr: raddr,
 			recv:  make(chan aurp.Packet, 1024),
 		}
-		nextConnID++
+		aurp.Inc(&nextConnID)
-		goHandler(peer)
 		peers[udpAddrFromNet(raddr)] = peer
+		goHandler(peer)
 	}
 
 	// Incoming packet loop
@@ -176,7 +180,6 @@ func main() {
 		pr := peers[ra]
 		if pr == nil {
 			// New peer!
-			nextConnID++
 			pr = &peer{
 				cfg: cfg,
 				tr: &aurp.Transport{
@@ -188,6 +191,7 @@ func main() {
 				raddr: raddr,
 				recv:  make(chan aurp.Packet, 1024),
 			}
+			aurp.Inc(&nextConnID)
 			peers[ra] = pr
 			goHandler(pr)
 		}