client: fix version display and rename client string

- Rename client to "Softether Go Client"
- Fix node info int fields to use LittleEndian32 encoding matching
  the C client's OutRpcNodeInfo (Admin.c:14693)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pkg/client/client.go

@@ -21,7 +21,7 @@ import (
 )
 
 const (
-	clientStr   = "SoftEther VPN Client"
+	clientStr   = "Softether Go Client"
 	clientVer   = 502
 	clientBuild = 5187
 
@@ -128,6 +128,14 @@ func Connect(cfg Config) (*Session, error) {
 	return sess, nil
 }
 
+// swapLE32 byte-swaps a uint32 to encode it as little-endian within a big-endian Pack int.
+// SoftEther's OutRpcNodeInfo wraps node info fields with LittleEndian32() before PackAddInt,
+// and InRpcNodeInfo reads them with LittleEndian32(PackGetInt(...)). Our Pack writes big-endian,
+// so we pre-swap to match the C client's wire format.
+func swapLE32(v uint32) uint32 {
+	return (v>>24)&0xFF | (v>>8)&0xFF00 | (v<<8)&0xFF0000 | (v<<24)&0xFF000000
+}
+
 // buildAuthPack constructs the authentication Pack sent to the server.
 // This includes credentials, client version, connection options, node info, and OS info.
 // See: https://github.com/SoftEtherVPN/SoftEtherVPN/blob/v5.02.5187/src/Cedar/Protocol.c#L7289
@@ -206,8 +214,10 @@ func buildAuthPack(cfg Config, random [sha1Size]byte) *protocol.Pack {
 	// (case-insensitive), and PackRead returns NULL on AddElement failure.
 	// p.AddStr("HubName", cfg.Hub)
 	p.AddData("UniqueId", uniqueID[:16])
-	p.AddInt("ClientProductVer", clientVer)
+	// Node info ints use LittleEndian32 encoding (see Admin.c:OutRpcNodeInfo).
-	p.AddInt("ClientProductBuild", clientBuild)
+	// The server reads them back with LittleEndian32(PackGetInt(...)).
+	p.AddInt("ClientProductVer", swapLE32(clientVer))
+	p.AddInt("ClientProductBuild", swapLE32(clientBuild))
 	p.AddInt("ServerProductVer", 0)
 	p.AddInt("ServerProductBuild", 0)
 	p.AddIP4("ClientIpAddress", 0)

pkg/netcfg/netcfg.go

@@ -30,6 +30,7 @@ func ConfigureTAP(ifname string, lease *dhcp.Lease, acceptDefaultGW, acceptStati
 	ones, _ := lease.SubnetMask.Size()
 	addr := fmt.Sprintf("%s/%d", lease.ClientIP, ones)
 
+	log.Printf("tap %s: adding address %s", ifname, addr)
 	if err := run("ip", "addr", "add", addr, "dev", ifname); err != nil {
 		return noop, fmt.Errorf("ip addr add: %w", err)
 	}
@@ -39,12 +40,16 @@ func ConfigureTAP(ifname string, lease *dhcp.Lease, acceptDefaultGW, acceptStati
 			dest := r.Dest.String()
 			if dest == "0.0.0.0/0" {
 				if acceptDefaultGW {
+					log.Printf("tap %s: adding static default route via %s", ifname, r.Gateway)
 					if err := run("ip", "route", "add", "default", "via", r.Gateway.String(), "dev", ifname, "metric", "50"); err != nil {
 						log.Printf("warning: static default route: %v", err)
 					}
+				} else {
+					log.Printf("tap %s: skipping static default route via %s (accept-default-gateway not set)", ifname, r.Gateway)
 				}
 				continue
 			}
+			log.Printf("tap %s: adding static route %s via %s", ifname, dest, r.Gateway)
 			if err := run("ip", "route", "add", dest, "via", r.Gateway.String(), "dev", ifname); err != nil {
 				log.Printf("warning: static route %s via %s: %v", dest, r.Gateway, err)
 			}
@@ -52,6 +57,7 @@ func ConfigureTAP(ifname string, lease *dhcp.Lease, acceptDefaultGW, acceptStati
 	}
 
 	if acceptDefaultGW && lease.Gateway != nil && !hasDefaultRoute(lease.Routes) {
+		log.Printf("tap %s: adding default route via %s", ifname, lease.Gateway)
 		if err := run("ip", "route", "add", "default", "via", lease.Gateway.String(), "dev", ifname, "metric", "50"); err != nil {
 			log.Printf("warning: default route: %v", err)
 		}
@@ -59,11 +65,13 @@ func ConfigureTAP(ifname string, lease *dhcp.Lease, acceptDefaultGW, acceptStati
 
 	var savedResolv []byte
 	if acceptDNS && len(lease.DNS) > 0 {
+		log.Printf("tap %s: setting DNS servers %v", ifname, lease.DNS)
 		savedResolv = backupResolv()
 		writeResolv(lease.DNS)
 	}
 
 	cleanup := func() {
+		log.Printf("tap %s: flushing addresses", ifname)
 		run("ip", "addr", "flush", "dev", ifname)
 		if savedResolv != nil {
 			restoreResolv(savedResolv)