Client-server working. No mediator.

README.md

@@ -2,6 +2,10 @@
 
 ## Roadmap
 
+* `node` package
+  * rename `peerRepo` to `routingTable`
+  * create router type with `Get(ip) *peer` and `Mediator() *peer` methods
+  * connReader / Writer should have access to the peerRepo
 * Use default port 456
 * Remove signing key from hub
 * Peer: UDP hole-punching

cmd/vppn/main.go

@@ -2,10 +2,10 @@ package main
 
 import (
 	"log"
-	"vppn/peer"
+	"vppn/node"
 )
 
 func main() {
 	log.SetFlags(0)
-	peer.Main()
+	node.Main()
 }

node/conn.go

@@ -4,30 +4,26 @@ import (
 	"log"
 	"net"
 	"net/netip"
+	"sync"
 	"sync/atomic"
 	"vppn/fasttime"
 )
 
-// TODO:
-type connRouter interface {
-	Lookup(byte) *peer
-	Mediator() *peer
-}
-
 type connWriter struct {
 	*net.UDPConn
+	lock     sync.Mutex
 	localIP  byte
 	buf      []byte
 	counters [256]uint64
-	lookup   func(byte) *peer
+	routing  *routingTable
 }
 
-func newConnWriter(conn *net.UDPConn, localIP byte, lookup func(byte) *peer) *connWriter {
+func newConnWriter(conn *net.UDPConn, localIP byte, routing *routingTable) *connWriter {
 	w := &connWriter{
 		UDPConn: conn,
 		localIP: localIP,
 		buf:     make([]byte, bufferSize),
-		lookup:  lookup,
+		routing: routing,
 	}
 
 	for i := range w.counters {
@@ -37,24 +33,36 @@ func newConnWriter(conn *net.UDPConn, localIP byte, lookup func(byte) *peer) *co
 	return w
 }
 
-func (w *connWriter) WriteTo(remoteIP, packetType byte, data []byte) error {
+func (w *connWriter) WriteTo(remoteIP, stream byte, data []byte) error {
-	peer := w.lookup(remoteIP)
+	// TODO: Handle mediator.
+	peer := w.routing.Get(remoteIP)
 	if peer == nil || peer.Addr == nil {
 		log.Printf("No peer: %d", remoteIP)
 		return nil
 	}
 
+	if stream == streamData && !peer.Up {
+		log.Printf("Peer down: %d", remoteIP)
+	}
+	return w.WriteToPeer(peer, stream, data)
+}
+
+func (w *connWriter) WriteToPeer(peer *peer, stream byte, data []byte) error {
+	w.lock.Lock()
+
+	remoteIP := peer.IP
 	h := header{
-		Counter:    atomic.AddUint64(&w.counters[remoteIP], 1),
+		Counter:  atomic.AddUint64(&w.counters[remoteIP], 1),
-		SourceIP:   w.localIP,
+		SourceIP: w.localIP,
-		ViaIP:      0,
+		ViaIP:    0,
-		DestIP:     remoteIP,
+		DestIP:   remoteIP,
-		PacketType: packetType,
+		Stream:   stream,
 	}
 
 	buf := encryptPacket(&h, peer.SharedKey, data, w.buf)
 
 	_, err := w.WriteToUDPAddrPort(buf, *peer.Addr)
+	w.lock.Unlock()
 	return err
 }
 
@@ -64,15 +72,15 @@ type connReader struct {
 	*net.UDPConn
 	localIP   byte
 	dupChecks [256]*dupCheck
-	lookup    func(byte) *peer
+	routing   *routingTable
 	buf       []byte
 }
 
-func newConnReader(conn *net.UDPConn, localIP byte, lookup func(byte) *peer) *connReader {
+func newConnReader(conn *net.UDPConn, localIP byte, routing *routingTable) *connReader {
 	r := &connReader{
 		UDPConn: conn,
 		localIP: localIP,
-		lookup:  lookup,
+		routing: routing,
 		buf:     make([]byte, bufferSize),
 	}
 	for i := range r.dupChecks {
@@ -93,18 +101,20 @@ func (r *connReader) Read(buf []byte) (remoteAddr netip.AddrPort, h header, data
 		data = buf[:n]
 
 		if n < headerSize {
+			log.Printf("Dropping short packet: %d", n)
 			continue // Packet it soo short.
 		}
 
 		h.Parse(data)
+
 		if len(data) != headerSize+int(h.DataSize) {
-			log.Printf("Incorrect size")
+			log.Printf("Malformed packet: %d != %d", len(data), headerSize+int(h.DataSize))
-			continue // Packet is corrupt.
+			continue
 		}
 
-		peer := r.lookup(h.SourceIP)
+		peer := r.routing.Get(h.SourceIP)
 		if peer == nil {
-			log.Printf("No peer...")
+			log.Printf("No peer: %d...", h.SourceIP)
 			continue
 		}
 
@@ -117,7 +127,7 @@ func (r *connReader) Read(buf []byte) (remoteAddr netip.AddrPort, h header, data
 		out, data = data, out
 
 		if r.dupChecks[h.SourceIP].IsDup(h.Counter) {
-			log.Printf("Duplicate...")
+			log.Printf("Duplicate: %d", h.Counter)
 			continue
 		}
 

node/crypto.go

@@ -1,6 +1,11 @@
 package node
 
-import "golang.org/x/crypto/nacl/box"
+import (
+	"sync"
+	"vppn/fasttime"
+
+	"golang.org/x/crypto/nacl/box"
+)
 
 // Encrypting the packet will also set the header's DataSize field.
 func encryptPacket(h *header, sharedKey, data, out []byte) []byte {
@@ -24,3 +29,23 @@ func computeSharedKey(peerPubKey, privKey []byte) []byte {
 	box.Precompute(&shared, (*[32]byte)(peerPubKey), (*[32]byte)(privKey))
 	return shared[:]
 }
+
+var (
+	traceIDLock    sync.Mutex
+	traceIDTime    uint64
+	traceIDCounter uint64
+)
+
+func newTraceID() (id uint64) {
+	traceIDLock.Lock()
+	defer traceIDLock.Unlock()
+
+	now := uint64(fasttime.Now())
+	if traceIDTime < now {
+		traceIDTime = now
+		traceIDCounter = 0
+	}
+	traceIDCounter++
+
+	return traceIDTime<<30 + traceIDCounter
+}

node/crypto_test.go

@@ -33,11 +33,11 @@ func TestEncryptDecryptPacket(t *testing.T) {
 	rand.Read(original)
 
 	h := header{
-		Counter:    2893749238,
+		Counter:  2893749238,
-		SourceIP:   5,
+		SourceIP: 5,
-		ViaIP:      8,
+		ViaIP:    8,
-		DestIP:     12,
+		DestIP:   12,
-		PacketType: 32,
+		Stream:   1,
 	}
 
 	encrypted := make([]byte, bufferSize)
@@ -62,7 +62,6 @@ func TestEncryptDecryptPacket(t *testing.T) {
 	}
 }
 
-/*
 func BenchmarkEncryptPacket(b *testing.B) {
 	_, privKey1, err := box.GenerateKey(rand.Reader)
 	if err != nil {
@@ -77,16 +76,24 @@ func BenchmarkEncryptPacket(b *testing.B) {
 	sharedEncKey := [32]byte{}
 	box.Precompute(&sharedEncKey, pubKey2, privKey1)
 
-	original := make([]byte, MTU)
+	original := make([]byte, if_mtu)
 	rand.Read(original)
 
-	nonce := make([]byte, NONCE_SIZE)
+	nonce := make([]byte, headerSize)
 	rand.Read(nonce)
 
-	encrypted := make([]byte, BUFFER_SIZE)
+	encrypted := make([]byte, bufferSize)
+
+	h := header{
+		Counter:  2893749238,
+		SourceIP: 5,
+		ViaIP:    8,
+		DestIP:   12,
+		Stream:   1,
+	}
 
 	for i := 0; i < b.N; i++ {
-		encrypted = encryptPacket(sharedEncKey[:], nonce, original, encrypted)
+		encrypted = encryptPacket(&h, sharedEncKey[:], original, encrypted)
 	}
 }
 
@@ -107,18 +114,27 @@ func BenchmarkDecryptPacket(b *testing.B) {
 	sharedDecKey := [32]byte{}
 	box.Precompute(&sharedDecKey, pubKey1, privKey2)
 
-	original := make([]byte, MTU)
+	original := make([]byte, if_mtu)
 	rand.Read(original)
 
-	nonce := make([]byte, NONCE_SIZE)
+	nonce := make([]byte, headerSize)
 	rand.Read(nonce)
 
-	encrypted := make([]byte, BUFFER_SIZE)
+	h := header{
-	encrypted = encryptPacket(sharedEncKey[:], nonce, original, encrypted)
+		Counter:  2893749238,
+		SourceIP: 5,
+		ViaIP:    8,
+		DestIP:   12,
+		Stream:   1,
+	}
 
-	decrypted := make([]byte, MTU)
+	encrypted := encryptPacket(&h, sharedEncKey[:], original, make([]byte, bufferSize))
+	decrypted := make([]byte, bufferSize)
+	var ok bool
 	for i := 0; i < b.N; i++ {
-		decrypted, _ = decryptPacket(sharedDecKey[:], encrypted, decrypted)
+		decrypted, ok = decryptPacket(sharedDecKey[:], encrypted, decrypted)
+		if !ok {
+			panic(ok)
+		}
 	}
 }
-*/

node/dupcheck.go

@@ -1,5 +1,7 @@
 package node
 
+import "log"
+
 type dupCheck struct {
 	bitSet
 	head        int
@@ -20,6 +22,7 @@ func (dc *dupCheck) IsDup(counter uint64) bool {
 
 	// Before head => it's late, say it's a dup.
 	if counter < dc.headCounter {
+		log.Printf("Late: %d", counter)
 		return true
 	}
 
@@ -27,6 +30,7 @@ func (dc *dupCheck) IsDup(counter uint64) bool {
 	if counter < dc.tailCounter {
 		index := (int(counter-dc.headCounter) + dc.head) % bitSetSize
 		if dc.Get(index) {
+			log.Printf("Dup: %d, %d", counter, dc.tailCounter)
 			return true
 		}
 

node/files.go

@@ -0,0 +1,82 @@
+package node
+
+import (
+	"encoding/json"
+	"log"
+	"os"
+	"path/filepath"
+	"vppn/m"
+)
+
+func configDir(netName string) string {
+	d, err := os.UserHomeDir()
+	if err != nil {
+		log.Fatalf("Failed to get user home directory: %v", err)
+	}
+	return filepath.Join(d, ".vppn", netName)
+}
+
+func peerConfigPath(netName string) string {
+	return filepath.Join(configDir(netName), "peer-config.json")
+}
+
+func peerStatePath(netName string) string {
+	return filepath.Join(configDir(netName), "peer-state.json")
+}
+
+func storeJson(x any, outPath string) error {
+	outDir := filepath.Dir(outPath)
+	_ = os.MkdirAll(outDir, 0700)
+
+	tmpPath := outPath + ".tmp"
+	buf, err := json.Marshal(x)
+	if err != nil {
+		return err
+	}
+
+	f, err := os.Create(tmpPath)
+	if err != nil {
+		return err
+	}
+
+	if _, err := f.Write(buf); err != nil {
+		f.Close()
+		return err
+	}
+
+	if err := f.Sync(); err != nil {
+		f.Close()
+		return err
+	}
+
+	if err := f.Close(); err != nil {
+		return err
+	}
+
+	return os.Rename(tmpPath, outPath)
+}
+
+func storePeerConfig(netName string, pc m.PeerConfig) error {
+	return storeJson(pc, peerConfigPath(netName))
+}
+
+func storeNetworkState(netName string, ps m.NetworkState) error {
+	return storeJson(ps, peerStatePath(netName))
+}
+
+func loadJson(dataPath string, ptr any) error {
+	data, err := os.ReadFile(dataPath)
+	if err != nil {
+		return err
+	}
+
+	return json.Unmarshal(data, ptr)
+}
+
+func loadPeerConfig(netName string) (pc m.PeerConfig, err error) {
+	return pc, loadJson(peerConfigPath(netName), &pc)
+}
+
+func loadNetworkState(netName string) (ps m.NetworkState, err error) {
+	return ps, loadJson(peerStatePath(netName), &ps)
+}

node/header.go

@@ -2,15 +2,19 @@ package node
 
 import "unsafe"
 
-const headerSize = 24
+const (
+	headerSize    = 24
+	streamData    = 1
+	streamRouting = 2
+)
 
 type header struct {
-	Counter    uint64 // Init with fasttime.Now() << 30 to ensure monotonic.
+	Counter  uint64 // Init with fasttime.Now() << 30 to ensure monotonic.
-	SourceIP   byte
+	SourceIP byte
-	ViaIP      byte
+	ViaIP    byte
-	DestIP     byte
+	DestIP   byte
-	PacketType byte   // The packet type. See PACKET_* constants.
+	Stream   byte   // See stream* constants.
-	DataSize   uint16 // Data size following associated data.
+	DataSize uint16 // Data size following associated data.
 }
 
 func (hdr *header) Parse(nb []byte) {
@@ -18,7 +22,7 @@ func (hdr *header) Parse(nb []byte) {
 	hdr.SourceIP = nb[8]
 	hdr.ViaIP = nb[9]
 	hdr.DestIP = nb[10]
-	hdr.PacketType = nb[11]
+	hdr.Stream = nb[11]
 	hdr.DataSize = *(*uint16)(unsafe.Pointer(&nb[12]))
 }
 
@@ -27,6 +31,6 @@ func (hdr header) Marshal(buf []byte) {
 	buf[8] = hdr.SourceIP
 	buf[9] = hdr.ViaIP
 	buf[10] = hdr.DestIP
-	buf[11] = hdr.PacketType
+	buf[11] = hdr.Stream
 	*(*uint16)(unsafe.Pointer(&buf[12])) = hdr.DataSize
 }

node/header_test.go

@@ -4,12 +4,12 @@ import "testing"
 
 func TestHeaderMarshalParse(t *testing.T) {
 	nIn := header{
-		Counter:    3212,
+		Counter:  3212,
-		SourceIP:   34,
+		SourceIP: 34,
-		ViaIP:      20,
+		ViaIP:    20,
-		DestIP:     200,
+		DestIP:   200,
-		PacketType: 44,
+		Stream:   44,
-		DataSize:   1235,
+		DataSize: 1235,
 	}
 
 	buf := make([]byte, headerSize)

node/interface.go

@@ -3,6 +3,7 @@ package node
 import (
 	"fmt"
 	"io"
+	"log"
 	"net"
 	"os"
 	"syscall"
@@ -22,23 +23,27 @@ func readNextPacket(iface io.ReadWriteCloser, buf []byte) ([]byte, byte, error)
 			return nil, ip, err
 		}
 
-		if n < 20 {
-			continue // Packet too short.
-		}
-
 		buf = buf[:n]
 		version = buf[0] >> 4
 
 		switch version {
 		case 4:
+			if n < 20 {
+				log.Printf("Short IPv4 packet: %d", len(buf))
+				continue
+			}
 			ip = buf[19]
+
 		case 6:
 			if len(buf) < 40 {
-				continue // Packet too short.
+				log.Printf("Short IPv6 packet: %d", len(buf))
+				continue
 			}
 			ip = buf[39]
+
 		default:
-			continue // Invalid version.
+			log.Printf("Invalid IP packet version: %v", version)
+			continue
 		}
 
 		return buf, ip, nil
@@ -47,7 +52,7 @@ func readNextPacket(iface io.ReadWriteCloser, buf []byte) ([]byte, byte, error)
 
 const (
 	if_mtu       = 1200
-	if_queue_len = 1000
+	if_queue_len = 2048
 )
 
 func openInterface(network []byte, localIP byte, name string) (io.ReadWriteCloser, error) {

node/main.go

@@ -0,0 +1,190 @@
+package node
+
+import (
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"net/http"
+	"net/netip"
+	"os"
+	"runtime/debug"
+	"vppn/m"
+)
+
+func panicHandler() {
+	if r := recover(); r != nil {
+		log.Fatalf("\n %v\n\nstacktrace from panic: %s\n", r, string(debug.Stack()))
+	}
+}
+
+func Main() {
+	defer panicHandler()
+
+	var (
+		netName  string
+		initURL  string
+		listenIP string
+		port     int
+	)
+
+	flag.StringVar(&netName, "name", "", "[REQUIRED] The network name.")
+	flag.StringVar(&initURL, "init-url", "", "Initializes peer from the hub URL.")
+	flag.StringVar(&listenIP, "listen-ip", "", "IP address to listen on.")
+	flag.IntVar(&port, "port", 0, "Port to listen on.")
+	flag.Parse()
+
+	if netName == "" {
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	if initURL != "" {
+		mainInit(netName, initURL)
+		return
+	}
+
+	main(netName, listenIP, uint16(port))
+}
+
+func mainInit(netName, initURL string) {
+	if _, err := loadPeerConfig(netName); err == nil {
+		log.Fatalf("Network is already initialized.")
+	}
+
+	resp, err := http.Get(initURL)
+	if err != nil {
+		log.Fatalf("Failed to fetch data from hub: %v", err)
+	}
+	defer resp.Body.Close()
+
+	data, err := io.ReadAll(resp.Body)
+	if err != nil {
+		log.Fatalf("Failed to read response body: %v", err)
+	}
+
+	peerConfig := m.PeerConfig{}
+	if err := json.Unmarshal(data, &peerConfig); err != nil {
+		log.Fatalf("Failed to parse configuration: %v", err)
+	}
+
+	if err := storePeerConfig(netName, peerConfig); err != nil {
+		log.Fatalf("Failed to store configuration: %v", err)
+	}
+
+	log.Print("Initialization successful.")
+}
+
+// ----------------------------------------------------------------------------
+
+func main(netName, listenIP string, port uint16) {
+	conf, err := loadPeerConfig(netName)
+	if err != nil {
+		log.Fatalf("Failed to load configuration: %v", err)
+	}
+
+	port = determinePort(conf.Port, port)
+
+	iface, err := openInterface(conf.Network, conf.PeerIP, netName)
+	if err != nil {
+		log.Fatalf("Failed to open interface: %v", err)
+	}
+
+	myAddr, err := net.ResolveUDPAddr("udp", fmt.Sprintf("%s:%d", listenIP, port))
+	if err != nil {
+		log.Fatalf("Failed to resolve UDP address: %v", err)
+	}
+
+	conn, err := net.ListenUDP("udp", myAddr)
+	if err != nil {
+		log.Fatalf("Failed to open UDP port: %v", err)
+	}
+
+	routing := newRoutingTable()
+
+	w := newConnWriter(conn, conf.PeerIP, routing)
+	r := newConnReader(conn, conf.PeerIP, routing)
+
+	router := newRouter(netName, conf, routing, w)
+
+	go nodeConnReader(r, w, iface, router)
+	nodeIFaceReader(w, iface, router)
+}
+
+// ----------------------------------------------------------------------------
+
+func determinePort(confPort, portFromCommandLine uint16) uint16 {
+	if portFromCommandLine != 0 {
+		return portFromCommandLine
+	}
+	if confPort != 0 {
+		return confPort
+	}
+	return 456
+}
+
+// ----------------------------------------------------------------------------
+
+func nodeConnReader(r *connReader, w *connWriter, iface io.ReadWriteCloser, router *router) {
+	defer panicHandler()
+	var (
+		remoteAddr netip.AddrPort
+		h          header
+		buf        = make([]byte, bufferSize)
+		data       []byte
+		err        error
+	)
+
+	for {
+		remoteAddr, h, data, err = r.Read(buf)
+		if err != nil {
+			log.Fatalf("Failed to read from UDP connection: %v", err)
+		}
+
+		switch h.Stream {
+
+		case streamData:
+			if _, err = iface.Write(data); err != nil {
+				log.Printf("Malformed data from peer %d: %v", h.SourceIP, err)
+			}
+
+		case streamRouting:
+			router.HandlePacket(h.SourceIP, remoteAddr, data)
+
+		default:
+			log.Printf("Dropping unknown stream: %d", h.Stream)
+		}
+	}
+}
+
+// ----------------------------------------------------------------------------
+
+func nodeIFaceReader(w *connWriter, iface io.ReadWriteCloser, router *router) {
+
+	var (
+		buf      = make([]byte, bufferSize)
+		packet   []byte
+		remoteIP byte
+		err      error
+	)
+
+	for {
+
+		packet, remoteIP, err = readNextPacket(iface, buf)
+		if err != nil {
+			log.Fatalf("Failed to read from interface: %v", err)
+		}
+
+		if remoteIP == w.localIP {
+			//log.Printf("Incoming packet for self: %x", packet)
+			//iface.Write(packet)
+			continue
+		}
+
+		if err := w.WriteTo(remoteIP, streamData, packet); err != nil {
+			log.Fatalf("Failed to write to network: %v", err)
+		}
+	}
+}

node/node.go

@@ -0,0 +1 @@
+package node

node/peer.go

@@ -1,30 +1 @@
 package node
-
-import (
-	"net/netip"
-	"sync/atomic"
-)
-
-type peer struct {
-	IP        byte
-	Addr      *netip.AddrPort // If we have direct connection, otherwise use mediator.
-	SharedKey []byte
-}
-
-type peerRepo [256]*atomic.Pointer[peer]
-
-func newPeerRepo() peerRepo {
-	pr := peerRepo{}
-	for i := range pr {
-		pr[i] = &atomic.Pointer[peer]{}
-	}
-	return pr
-}
-
-func (pr peerRepo) Get(ip byte) *peer {
-	return pr[ip].Load()
-}
-
-func (pr *peerRepo) Set(ip byte, p *peer) {
-	pr[ip].Store(p)
-}

node/peerstate.go

@@ -0,0 +1 @@
+package node

node/router.go

@@ -0,0 +1,163 @@
+package node
+
+import (
+	"encoding/json"
+	"io"
+	"log"
+	"net/http"
+	"net/netip"
+	"net/url"
+	"sync/atomic"
+	"time"
+	"vppn/m"
+)
+
+type peer struct {
+	Up        bool // No data will be sent to peers that are down.
+	IP        byte
+	Addr      *netip.AddrPort // If we have direct connection, otherwise use mediator.
+	SharedKey []byte
+}
+
+// ----------------------------------------------------------------------------
+
+type routingTable struct {
+	table    [256]*atomic.Pointer[peer]
+	mediator *atomic.Pointer[peer]
+}
+
+func newRoutingTable() *routingTable {
+	r := routingTable{
+		mediator: &atomic.Pointer[peer]{},
+	}
+
+	for i := range r.table {
+		r.table[i] = &atomic.Pointer[peer]{}
+	}
+
+	return &r
+}
+
+func (r *routingTable) Get(ip byte) *peer {
+	return r.table[ip].Load()
+}
+
+func (r *routingTable) Set(ip byte, p *peer) {
+	r.table[ip].Store(p)
+}
+
+// ----------------------------------------------------------------------------
+
+type router struct {
+	netName string
+	*routingTable
+	peerSupers [256]*peerSupervisor
+}
+
+func newRouter(netName string, conf m.PeerConfig, routingData *routingTable, w *connWriter) *router {
+	r := &router{
+		netName:      netName,
+		routingTable: routingData,
+	}
+
+	for i := range r.peerSupers {
+		r.peerSupers[i] = newPeerSupervisor(
+			conf,
+			byte(i),
+			w,
+			r.routingTable)
+	}
+
+	// TODO: Handle Mediator
+	go r.pollHub(conf)
+
+	return r
+}
+
+// ----------------------------------------------------------------------------
+
+func (r *router) HandlePacket(sourceIP byte, remoteAddr netip.AddrPort, data []byte) {
+	p := routingPacket{}
+	if err := p.Parse(data); err != nil {
+		log.Printf("Dropping malformed routing packet: %v", err)
+		return
+	}
+
+	w := routingPacketWrapper{
+		routingPacket: p,
+		Addr:          remoteAddr,
+	}
+
+	r.peerSupers[sourceIP].HandlePacket(w)
+}
+
+// ----------------------------------------------------------------------------
+
+func (r *router) pollHub(conf m.PeerConfig) {
+	defer panicHandler()
+
+	u, err := url.Parse(conf.HubAddress)
+	if err != nil {
+		log.Fatalf("Failed to parse hub address %s: %v", conf.HubAddress, err)
+	}
+	u.Path = "/peer/fetch-state/"
+
+	client := &http.Client{Timeout: 8 * time.Second}
+
+	req := &http.Request{
+		Method: http.MethodGet,
+		URL:    u,
+		Header: http.Header{},
+	}
+	req.SetBasicAuth("", conf.APIKey)
+
+	// TODO: Before we start polling, load state from the file system.
+	state, err := loadNetworkState(r.netName)
+	if err != nil {
+		log.Printf("Failed to load network state: %v", err)
+		log.Printf("Polling hub...")
+		r._pollHub(conf, client, req)
+	} else {
+		r.applyNetworkState(conf, state)
+	}
+
+	for range time.Tick(64 * time.Second) {
+		r._pollHub(conf, client, req)
+	}
+}
+
+func (r *router) _pollHub(conf m.PeerConfig, client *http.Client, req *http.Request) {
+	var state m.NetworkState
+
+	log.Printf("Fetching peer state from %s...", conf.HubAddress)
+	resp, err := client.Do(req)
+	if err != nil {
+		log.Printf("Failed to fetch peer state: %v", err)
+		return
+	}
+	body, err := io.ReadAll(resp.Body)
+	_ = resp.Body.Close()
+	if err != nil {
+		log.Printf("Failed to read body from hub: %v", err)
+		return
+	}
+
+	if err := json.Unmarshal(body, &state); err != nil {
+		log.Printf("Failed to unmarshal response from hub: %v", err)
+		return
+	}
+
+	r.applyNetworkState(conf, state)
+
+	if err := storeNetworkState(r.netName, state); err != nil {
+		log.Printf("Failed to store network state: %v", err)
+	}
+}
+
+func (r *router) applyNetworkState(conf m.PeerConfig, state m.NetworkState) {
+	for i := range state.Peers {
+		if i != int(conf.PeerIP) {
+			r.peerSupers[i].HandlePeerUpdate(state.Peers[i])
+		}
+	}
+}

node/routingpacket.go

@@ -0,0 +1,44 @@
+package node
+
+import (
+	"errors"
+	"unsafe"
+)
+
+var errMalformedPacket = errors.New("malformed packet")
+
+const (
+	packetTypeInvalid = iota
+
+	// Used to maintain connection.
+	packetTypePing
+	packetTypePong
+)
+
+type routingPacket struct {
+	Type    byte   // One of the packetType* constants.
+	TraceID uint64 // For matching requests and responses.
+}
+
+func newRoutingPacket(reqType byte, traceID uint64) routingPacket {
+	return routingPacket{
+		Type:    reqType,
+		TraceID: traceID,
+	}
+}
+
+func (p routingPacket) Marshal(buf []byte) []byte {
+	buf = buf[:32] // Reserve 32 bytes just in case we need to add anything.
+	buf[0] = p.Type
+	*(*uint64)(unsafe.Pointer(&buf[1])) = uint64(p.TraceID)
+	return buf
+}
+
+func (p *routingPacket) Parse(buf []byte) error {
+	if len(buf) != 32 {
+		return errMalformedPacket
+	}
+	p.Type = buf[0]
+	p.TraceID = *(*uint64)(unsafe.Pointer(&buf[1]))
+	return nil
+}

node/tmp-server.go

@@ -1,14 +1,6 @@
 package node
 
-import (
+/*
-	"fmt"
-	"io"
-	"log"
-	"net"
-	"net/netip"
-	"runtime/debug"
-)
-
 var (
 	network  = []byte{10, 1, 1, 0}
 	serverIP = byte(1)
@@ -30,7 +22,7 @@ func must(err error) {
 type TmpNode struct {
 	network []byte
 	localIP byte
-	peers   peerRepo
+	router  *router
 	port    uint16
 	netName string
 	iface   io.ReadWriteCloser
@@ -46,7 +38,7 @@ func NewTmpNodeServer() *TmpNode {
 	n := &TmpNode{
 		localIP: serverIP,
 		network: network,
-		peers:   newPeerRepo(),
+		router:  &router{table: newPeerRepo()},
 		port:    port,
 		netName: netName,
 		pubKey:  pubKey1,
@@ -63,10 +55,10 @@ func NewTmpNodeServer() *TmpNode {
 	conn, err := net.ListenUDP("udp", myAddr)
 	must(err)
 
-	n.w = newConnWriter(conn, n.localIP, n.peers.Get)
+	n.w = newConnWriter(conn, n.localIP, n.router)
-	n.r = newConnReader(conn, n.localIP, n.peers.Get)
+	n.r = newConnReader(conn, n.localIP, n.router)
 
-	n.peers.Set(clientIP, &peer{
+	n.router.table.Set(clientIP, &peer{
 		IP:        clientIP,
 		SharedKey: computeSharedKey(pubKey2, n.privKey),
 	})
@@ -80,7 +72,7 @@ func NewTmpNodeClient(srvAddrStr string) *TmpNode {
 	n := &TmpNode{
 		localIP: clientIP,
 		network: network,
-		peers:   newPeerRepo(),
+		router:  &router{table: newPeerRepo()},
 		port:    port,
 		netName: netName,
 		pubKey:  pubKey2,
@@ -97,13 +89,13 @@ func NewTmpNodeClient(srvAddrStr string) *TmpNode {
 	conn, err := net.ListenUDP("udp", myAddr)
 	must(err)
 
-	n.w = newConnWriter(conn, n.localIP, n.peers.Get)
+	n.w = newConnWriter(conn, n.localIP, n.router)
-	n.r = newConnReader(conn, n.localIP, n.peers.Get)
+	n.r = newConnReader(conn, n.localIP, n.router)
 
 	serverAddr, err := netip.ParseAddrPort(fmt.Sprintf("%s:%d", srvAddrStr, port))
 	must(err)
 
-	n.peers.Set(serverIP, &peer{
+	n.router.table.Set(serverIP, &peer{
 		IP:        serverIP,
 		Addr:      &serverAddr,
 		SharedKey: computeSharedKey(pubKey1, n.privKey),
@@ -129,7 +121,7 @@ func (n *TmpNode) RunServer() {
 	log.Printf("Got remote addr: %d -> %v", h.SourceIP, remoteAddr)
 	must(err)
 
-	n.peers.Set(h.SourceIP, &peer{
+	n.router.table.Set(h.SourceIP, &peer{
 		IP:        h.SourceIP,
 		Addr:      &remoteAddr,
 		SharedKey: computeSharedKey(pubKey2, n.privKey),
@@ -144,7 +136,7 @@ func (n *TmpNode) RunServer() {
 func (n *TmpNode) RunClient() {
 	defer func() {
 		if r := recover(); r != nil {
-			fmt.Printf("%v", r)
+			fmt.Printf("%v\n", r)
 			debug.PrintStack()
 		}
 	}()
@@ -184,6 +176,10 @@ func (node *TmpNode) readFromConn() {
 		// We assume that we're only receiving packets from one source.
 
 		_, err = node.iface.Write(packet)
-		must(err)
+		if err != nil {
+			log.Printf("Got error: %v", err)
+		}
+		//must(err)
 	}
 }
+*/

node/tmp_peerstate.go

@@ -0,0 +1,312 @@
+package node
+
+import (
+	"fmt"
+	"log"
+	"net/netip"
+	"time"
+	"vppn/m"
+)
+
+const (
+	connectTimeout  = 6 * time.Second
+	pingInterval    = 6 * time.Second
+	timeoutInterval = 20 * time.Second
+)
+
+type routingPacketWrapper struct {
+	routingPacket
+	Addr netip.AddrPort // Source.
+}
+
+type peerSupervisor struct {
+	// Constants:
+	localIP     byte
+	localPublic bool
+	remoteIP    byte
+	privKey     []byte
+
+	// Shared data:
+	w     *connWriter
+	table *routingTable
+
+	packets     chan routingPacketWrapper
+	peerUpdates chan *m.Peer
+
+	// Peer-related items.
+	version        int64 // Ony accessed in HandlePeerUpdate.
+	peer           *m.Peer
+	remoteAddrPort *netip.AddrPort
+	sharedKey      []byte
+
+	// Used by our state functions.
+	pingTimer    *time.Timer
+	timeoutTimer *time.Timer
+	buf          []byte
+}
+
+// ----------------------------------------------------------------------------
+
+func newPeerSupervisor(
+	conf m.PeerConfig,
+	remoteIP byte,
+	w *connWriter,
+	table *routingTable,
+) *peerSupervisor {
+	s := &peerSupervisor{
+		localIP:      conf.PeerIP,
+		remoteIP:     remoteIP,
+		privKey:      conf.EncPrivKey,
+		w:            w,
+		table:        table,
+		packets:      make(chan routingPacketWrapper, 256),
+		peerUpdates:  make(chan *m.Peer, 1),
+		pingTimer:    time.NewTimer(pingInterval),
+		timeoutTimer: time.NewTimer(timeoutInterval),
+		buf:          make([]byte, bufferSize),
+	}
+
+	_, s.localPublic = netip.AddrFromSlice(conf.PublicIP)
+
+	go s.mainLoop()
+	return s
+}
+
+func (s *peerSupervisor) logf(msg string, args ...any) {
+	msg = fmt.Sprintf("[%03d] ", s.remoteIP) + msg
+	log.Printf(msg, args...)
+}
+
+// ----------------------------------------------------------------------------
+
+func (s *peerSupervisor) mainLoop() {
+	defer panicHandler()
+	state := s.stateInit
+	for {
+		state = state()
+	}
+}
+
+// ----------------------------------------------------------------------------
+
+func (s *peerSupervisor) HandlePeerUpdate(p *m.Peer) {
+	if p != nil {
+		if p.Version == s.version {
+			return
+		}
+		s.logf("New peer version: %d", p.Version)
+		s.version = p.Version
+	} else {
+		s.version = 0
+	}
+
+	s.peerUpdates <- p
+}
+
+func (s *peerSupervisor) HandlePacket(w routingPacketWrapper) {
+	select {
+	case s.packets <- w:
+	default:
+		// Drop
+	}
+}
+
+// ----------------------------------------------------------------------------
+
+type stateFunc func() stateFunc
+
+func (s *peerSupervisor) stateInit() stateFunc {
+	if s.peer == nil {
+		return s.stateDisconnected
+	}
+
+	addr, ok := netip.AddrFromSlice(s.peer.PublicIP)
+	if ok {
+		addrPort := netip.AddrPortFrom(addr, s.peer.Port)
+		s.remoteAddrPort = &addrPort
+	} else {
+		s.remoteAddrPort = nil
+	}
+	s.sharedKey = computeSharedKey(s.peer.EncPubKey, s.privKey)
+
+	return s.stateSelectRole()
+}
+
+// ----------------------------------------------------------------------------
+
+func (s *peerSupervisor) stateDisconnected() stateFunc {
+	s.clearRoutingTable()
+
+	for {
+		select {
+		case <-s.packets:
+			// Drop
+		case s.peer = <-s.peerUpdates:
+			return s.stateInit
+		}
+	}
+}
+
+// ----------------------------------------------------------------------------
+
+func (s *peerSupervisor) stateSelectRole() stateFunc {
+	s.logf("STATE: SelectRole")
+	s.updateRoutingTable(false)
+
+	if s.remoteAddrPort != nil {
+		// If both remote and local are public, one side acts as client, and one
+		// side as server.
+		if s.localPublic && s.localIP < s.peer.PeerIP {
+			return s.stateAccept
+		}
+		return s.stateDial
+	}
+
+	// We're public, remote is not => can only wait for connection
+	if s.localPublic {
+		return s.stateAccept
+	}
+
+	// Both non-public => need to use mediator.
+	return s.stateMediated
+}
+
+// ----------------------------------------------------------------------------
+
+func (s *peerSupervisor) stateAccept() stateFunc {
+	s.logf("STATE: Accept")
+
+	for {
+
+		select {
+		case pkt := <-s.packets:
+			switch pkt.Type {
+
+			case packetTypePing:
+				s.remoteAddrPort = &pkt.Addr
+				s.updateRoutingTable(true)
+				s.sendPong(pkt.TraceID)
+				return s.stateConnected
+
+			default:
+				// Still waiting for ping...
+			}
+
+		case s.peer = <-s.peerUpdates:
+			return s.stateInit
+		}
+	}
+}
+
+// ----------------------------------------------------------------------------
+
+func (s *peerSupervisor) stateDial() stateFunc {
+	s.logf("STATE: Dial")
+	s.updateRoutingTable(false)
+
+	s.sendPing()
+
+	for {
+		select {
+		case pkt := <-s.packets:
+
+			switch pkt.Type {
+
+			case packetTypePong:
+				s.updateRoutingTable(true)
+				return s.stateConnected
+
+			default:
+				// Ignore
+			}
+
+		case <-s.pingTimer.C:
+			s.sendPing()
+
+		case s.peer = <-s.peerUpdates:
+			return s.stateInit
+		}
+	}
+}
+
+// ----------------------------------------------------------------------------
+
+func (s *peerSupervisor) stateConnected() stateFunc {
+	s.logf("STATE: Connected")
+
+	s.timeoutTimer.Reset(timeoutInterval)
+
+	for {
+		select {
+
+		case <-s.pingTimer.C:
+			s.sendPing()
+
+		case <-s.timeoutTimer.C:
+			s.logf("Timeout")
+			return s.stateInit
+
+		case pkt := <-s.packets:
+			switch pkt.Type {
+			case packetTypePing:
+				s.sendPong(pkt.TraceID)
+
+				// Server should always follow remote port.
+				if s.localPublic {
+					if pkt.Addr != *s.remoteAddrPort {
+						s.remoteAddrPort = &pkt.Addr
+						s.updateRoutingTable(true)
+					}
+				}
+
+			case packetTypePong:
+				s.timeoutTimer.Reset(timeoutInterval)
+
+			default:
+				// Drop packet.
+			}
+
+		case s.peer = <-s.peerUpdates:
+			s.logf("New peer: %v", s.peer)
+			return s.stateInit
+		}
+	}
+}
+
+// ----------------------------------------------------------------------------
+
+func (s *peerSupervisor) stateMediated() stateFunc {
+	s.logf("STATE: Mediated")
+	// TODO
+	select {}
+}
+
+// ----------------------------------------------------------------------------
+
+func (s *peerSupervisor) clearRoutingTable() {
+	s.table.Set(s.remoteIP, nil)
+}
+
+func (s *peerSupervisor) updateRoutingTable(up bool) {
+	s.table.Set(s.remoteIP, &peer{
+		Up:        up,
+		IP:        s.remoteIP,
+		Addr:      s.remoteAddrPort,
+		SharedKey: s.sharedKey,
+	})
+}
+
+// ----------------------------------------------------------------------------
+
+func (s *peerSupervisor) sendPing() uint64 {
+	traceID := newTraceID()
+	pkt := newRoutingPacket(packetTypePing, traceID)
+	s.w.WriteTo(s.peer.PeerIP, streamRouting, pkt.Marshal(s.buf))
+	s.pingTimer.Reset(pingInterval)
+	return traceID
+}
+
+func (s *peerSupervisor) sendPong(traceID uint64) {
+	pkt := newRoutingPacket(packetTypePong, traceID)
+	s.w.WriteTo(s.peer.PeerIP, streamRouting, pkt.Marshal(s.buf))
+}