Added go-binding for mobile port

Signed-off-by: Roberto Urbano <rurbano@users.noreply.github.com>

mobile/mobile.go

@@ -0,0 +1,489 @@
+// Package mobile provides a gomobile-compatible facade for running a Hyprspace
+// node on Android. It bridges Android's VpnService TUN file descriptor with the
+// Hyprspace libp2p networking layer.
+//
+// Build with:
+//
+//	gomobile bind -javapkg hyprspace -target=android -androidapi 26 -o hyprspace.aar ./mobile
+package mobile
+
+import (
+	"context"
+	"encoding/binary"
+	"errors"
+	"io/fs"
+	"net"
+	"os"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/hyprspace/hyprspace/config"
+	"github.com/hyprspace/hyprspace/p2p"
+	"github.com/ipfs/go-log/v2"
+	"github.com/libp2p/go-cidranger"
+	dht "github.com/libp2p/go-libp2p-kad-dht"
+	"github.com/libp2p/go-libp2p/core/connmgr"
+	"github.com/libp2p/go-libp2p/core/control"
+	"github.com/libp2p/go-libp2p/core/crypto"
+	"github.com/libp2p/go-libp2p/core/host"
+	"github.com/libp2p/go-libp2p/core/network"
+	"github.com/libp2p/go-libp2p/core/peer"
+	ma "github.com/multiformats/go-multiaddr"
+	"github.com/multiformats/go-multibase"
+	"go.uber.org/zap"
+)
+
+var logger = log.Logger("hyprspace/mobile")
+
+// Identity is this node's stable cryptographic identity, returned by
+// GenerateIdentity for first-launch config creation.
+type Identity struct {
+	// PrivateKey is the multibase (Base58BTC) encoded libp2p private key.
+	// Persist it verbatim in the config's "privateKey" field.
+	PrivateKey string
+	// PeerID is the libp2p peer ID derived from the key, for display.
+	PeerID string
+}
+
+// GenerateIdentity creates a fresh Ed25519 libp2p identity. Call it once on
+// first launch when no config file exists; persist PrivateKey in the config's
+// "privateKey" field. The peer ID and tunnel addresses are all derived from
+// this key (use GetVPNConfig for the addresses after the file is written).
+func GenerateIdentity() (*Identity, error) {
+	privKey, _, err := crypto.GenerateKeyPair(crypto.Ed25519, 256)
+	if err != nil {
+		return nil, err
+	}
+	keyBytes, err := crypto.MarshalPrivateKey(privKey)
+	if err != nil {
+		return nil, err
+	}
+	peerID, err := peer.IDFromPrivateKey(privKey)
+	if err != nil {
+		return nil, err
+	}
+	return &Identity{
+		PrivateKey: multibase.MustNewEncoder(multibase.Base58BTC).Encode(keyBytes),
+		PeerID:     peerID.String(),
+	}, nil
+}
+
+// VPNConfig contains the network parameters that Android's VpnService.Builder
+// needs before calling establish() to create the TUN device.
+type VPNConfig struct {
+	// Address4 is the IPv4 address with prefix, e.g. "100.64.1.2/32".
+	Address4 string
+	// Address6 is the IPv6 address with prefix, e.g. "fd00:...:abcd/128".
+	Address6 string
+	// MTU for the tunnel interface.
+	MTU int
+	// Routes is a newline-separated list of CIDRs to route through the VPN.
+	Routes string
+}
+
+// GetVPNConfig reads the hyprspace configuration and returns the network
+// parameters needed to configure Android's VpnService.Builder.
+// Call this before StartNode to know what addresses/routes to set up.
+func GetVPNConfig(configPath string) (*VPNConfig, error) {
+	cfg, err := config.Read(configPath)
+	if err != nil {
+		return nil, err
+	}
+
+	allRoutes4, err := cfg.PeerLookup.ByRoute.CoveredNetworks(*cidranger.AllIPv4)
+	if err != nil {
+		return nil, err
+	}
+	allRoutes6, err := cfg.PeerLookup.ByRoute.CoveredNetworks(*cidranger.AllIPv6)
+	if err != nil {
+		return nil, err
+	}
+
+	var routes []string
+	for _, r := range allRoutes4 {
+		n := r.Network()
+		routes = append(routes, n.String())
+	}
+	for _, r := range allRoutes6 {
+		n := r.Network()
+		routes = append(routes, n.String())
+	}
+
+	return &VPNConfig{
+		Address4: cfg.BuiltinAddr4.String() + "/32",
+		Address6: cfg.BuiltinAddr6.String() + "/128",
+		MTU:      1420,
+		Routes:   strings.Join(routes, "\n"),
+	}, nil
+}
+
+// Node is a running Hyprspace instance on Android.
+type Node struct {
+	cfg           *config.Config
+	host          host.Host
+	dht           *dht.IpfsDHT
+	tunFile       *os.File
+	activeStreams map[peer.ID]*sharedStream
+	streamsMu     sync.Mutex
+	healthNotify  *network.NotifyBundle
+	ctx           context.Context
+	cancel        context.CancelFunc
+	wg            sync.WaitGroup
+
+	events        Events
+	stateMu       sync.Mutex
+	lastState     string
+	lastConnected int
+}
+
+// Events receives node lifecycle and health notifications. It is implemented on
+// the Android side and passed to StartNode.
+//
+// Methods may be called from arbitrary goroutines (libp2p network
+// notifications, the TUN read loop, etc.), so the implementation must be
+// thread-safe and MUST NOT block — post to a Handler or update a thread-safe
+// holder such as a StateFlow. Do not call back into Go synchronously from these
+// callbacks.
+type Events interface {
+	// OnStateChange reports a lifecycle transition. state is one of:
+	//   "running"   – node started; no configured peer connected yet
+	//   "connected" – at least one configured peer is reachable
+	//   "stopped"   – clean shutdown
+	//   "error"     – fatal; detail holds the message; the node is down
+	OnStateChange(state string, detail string)
+
+	// OnPeerCountChange reports how many configured peers are currently
+	// connected, out of the total configured.
+	OnPeerCountChange(connected int, total int)
+}
+
+// emit reports a lifecycle state change, deduplicating repeated states so the
+// Android side is not spammed. The Events callback is invoked without holding
+// stateMu to avoid deadlocks if the implementation re-enters.
+func (n *Node) emit(state, detail string) {
+	if n.events == nil {
+		return
+	}
+	n.stateMu.Lock()
+	if state == n.lastState {
+		n.stateMu.Unlock()
+		return
+	}
+	n.lastState = state
+	n.stateMu.Unlock()
+	n.events.OnStateChange(state, detail)
+}
+
+// emitPeers reports a change in the number of connected configured peers,
+// deduplicating identical counts.
+func (n *Node) emitPeers(connected, total int) {
+	if n.events == nil {
+		return
+	}
+	n.stateMu.Lock()
+	if connected == n.lastConnected {
+		n.stateMu.Unlock()
+		return
+	}
+	n.lastConnected = connected
+	n.stateMu.Unlock()
+	n.events.OnPeerCountChange(connected, total)
+}
+
+// registerHealth subscribes to libp2p connection events and reports how many
+// configured peers are currently reachable, transitioning between the
+// "running" (no peers) and "connected" (>=1 peer) states.
+func (n *Node) registerHealth() {
+	// Notify callbacks can be invoked while libp2p is mutating/closing network
+	// state. Bounce health calculation to a separate goroutine so the callback
+	// does not synchronously re-enter n.host.Network().
+	n.healthNotify = &network.NotifyBundle{
+		ConnectedF:    func(network.Network, network.Conn) { go n.updateHealth() },
+		DisconnectedF: func(network.Network, network.Conn) { go n.updateHealth() },
+	}
+	n.host.Network().Notify(n.healthNotify)
+}
+
+func (n *Node) updateHealth() {
+	if n.ctx.Err() != nil {
+		return
+	}
+
+	connected := 0
+	for _, p := range n.cfg.Peers {
+		if n.host.Network().Connectedness(p.ID) == network.Connected {
+			connected++
+		}
+	}
+	n.emitPeers(connected, len(n.cfg.Peers))
+	if connected > 0 {
+		n.emit("connected", "")
+	} else {
+		n.emit("running", "")
+	}
+}
+
+type sharedStream struct {
+	stream network.Stream
+	mu     sync.Mutex
+}
+
+// StartNode starts a Hyprspace node using a TUN file descriptor from Android's
+// VpnService. The fd must be obtained via ParcelFileDescriptor.detachFd() after
+// VpnService.Builder.establish(). configPath is the path to the hyprspace JSON
+// config file on the Android filesystem. events receives lifecycle and health
+// notifications and may be nil.
+// For Android: Call `pfd.detachFd()` and pass that int; never close the `ParcelFileDescriptor`
+// yourself. (it would double-close)
+func StartNode(fd int, configPath string, events Events) (*Node, error) {
+	log.SetLogLevel("hyprspace", "info")
+	log.SetLogLevelRegex("^hyprspace/", "info")
+
+	cfg, err := config.Read(configPath)
+	if err != nil {
+		return nil, err
+	}
+	cfg.Interface = "hyprspace"
+
+	tunFile := os.NewFile(uintptr(fd), "vpn-tun")
+	if tunFile == nil {
+		return nil, errors.New("invalid file descriptor")
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+
+	n := &Node{
+		cfg:           cfg,
+		tunFile:       tunFile,
+		activeStreams: make(map[peer.ID]*sharedStream),
+		ctx:           ctx,
+		cancel:        cancel,
+		events:        events,
+	}
+
+	// Use passthrough gater since Android VpnService handles routing protection
+	// and netlink is unavailable.
+	var gater connmgr.ConnectionGater = passthroughGater{}
+
+	n.host, n.dht, err = p2p.CreateNode(
+		ctx,
+		cfg.PrivateKey,
+		cfg.ListenAddresses,
+		n.streamHandler,
+		p2p.NewClosedCircuitRelayFilter(cfg.Peers),
+		gater,
+		cfg.Peers,
+	)
+	if err != nil {
+		cancel()
+		tunFile.Close()
+		return nil, err
+	}
+
+	n.host.SetStreamHandler(p2p.PeXProtocol, p2p.NewPeXStreamHandler(n.host, cfg))
+
+	for _, p := range cfg.Peers {
+		n.host.ConnManager().Protect(p.ID, "/hyprspace/peer")
+	}
+
+	go p2p.Discover(ctx, &n.wg, n.host, n.dht, cfg.Peers)
+	go p2p.PeXService(ctx, &n.wg, n.host, cfg)
+	go p2p.RouteMetricsService(ctx, &n.wg, n.host, cfg)
+
+	go n.readLoop()
+
+	n.registerHealth()
+	n.emit("running", "")
+
+	logger.Info("Mobile node started")
+	return n, nil
+}
+
+// Stop gracefully shuts down the Hyprspace node.
+func (n *Node) Stop() error {
+	started := time.Now()
+	logger.Info("Stopping mobile node")
+
+	logger.Info("Stopping mobile node: cancel context")
+	n.cancel()
+
+	if n.healthNotify != nil {
+		logger.Info("Stopping mobile node: unregistering health notifier")
+		n.host.Network().StopNotify(n.healthNotify)
+		n.healthNotify = nil
+		logger.With(zap.Duration("elapsed", time.Since(started))).Info("Stopping mobile node: health notifier unregistered")
+	}
+
+	logger.Info("Stopping mobile node: closing TUN fd")
+	if tunErr := n.tunFile.Close(); tunErr != nil {
+		logger.With(zap.Error(tunErr)).Warn("Stopping mobile node: TUN fd close returned error")
+	}
+	logger.With(zap.Duration("elapsed", time.Since(started))).Info("Stopping mobile node: TUN fd closed")
+
+	logger.Info("Stopping mobile node: closing host")
+	err := n.host.Close()
+	if err != nil {
+		logger.With(zap.Error(err)).Warn("Stopping mobile node: host close returned error")
+	}
+	logger.With(zap.Duration("elapsed", time.Since(started))).Info("Stopping mobile node: host closed")
+
+	logger.Info("Stopping mobile node: waiting for background services")
+	n.wg.Wait()
+	logger.With(zap.Duration("elapsed", time.Since(started))).Info("Stopping mobile node: background services stopped")
+
+	n.emit("stopped", "")
+	logger.With(zap.Duration("elapsed", time.Since(started))).Info("Mobile node stopped")
+	return err
+}
+
+// Rebootstrap forces a DHT refresh and peer rediscovery.
+func (n *Node) Rebootstrap() {
+	n.host.ConnManager().TrimOpenConns(context.Background())
+	<-n.dht.ForceRefresh()
+	p2p.Rediscover()
+}
+
+// readLoop reads IP packets from the TUN fd and dispatches them to peers.
+func (n *Node) readLoop() {
+	for {
+		packet := make([]byte, 1420)
+		plen, err := n.tunFile.Read(packet)
+		if err != nil {
+			if errors.Is(err, fs.ErrClosed) || errors.Is(err, os.ErrClosed) {
+				logger.Warn("TUN closed, stopping read loop")
+				// A close that did not originate from Stop() means the tunnel
+				// died on its own; surface it as a fatal error.
+				if n.ctx.Err() == nil {
+					n.emit("error", "tunnel closed unexpectedly")
+				}
+				return
+			}
+			if n.ctx.Err() != nil {
+				return
+			}
+			logger.With(zap.Error(err)).Error("Failed to read from TUN")
+			continue
+		}
+
+		var dstIP net.IP
+		proto := packet[0] & 0xf0
+
+		if proto == 0x40 {
+			dstIP = net.IP(packet[16:20])
+			if n.cfg.BuiltinAddr4.Equal(dstIP) {
+				continue
+			}
+		} else if proto == 0x60 {
+			dstIP = net.IP(packet[24:40])
+			if n.cfg.BuiltinAddr6.Equal(dstIP) {
+				continue
+			}
+		} else {
+			continue
+		}
+
+		route, found := n.cfg.FindRouteForIP(dstIP)
+		if found {
+			go n.sendPacket(route.Target.ID, packet, plen)
+		}
+	}
+}
+
+// streamHandler handles incoming packets from peers and writes them to the TUN.
+func (n *Node) streamHandler(stream network.Stream) {
+	if _, ok := config.FindPeer(n.cfg.Peers, stream.Conn().RemotePeer()); !ok {
+		stream.Reset()
+		return
+	}
+	packet := make([]byte, 1420)
+	packetSize := make([]byte, 2)
+	for {
+		_, err := stream.Read(packetSize)
+		if err != nil {
+			stream.Close()
+			return
+		}
+
+		size := binary.LittleEndian.Uint16(packetSize)
+
+		var plen uint16
+		for plen < size {
+			tmp, err := stream.Read(packet[plen:size])
+			plen += uint16(tmp)
+			if err != nil {
+				stream.Close()
+				return
+			}
+		}
+		_ = stream.SetWriteDeadline(time.Now().Add(25 * time.Second))
+		_, _ = n.tunFile.Write(packet[:size])
+	}
+}
+
+// sendPacket sends a packet to a peer, reusing existing streams when possible.
+func (n *Node) sendPacket(dst peer.ID, packet []byte, plen int) {
+	n.streamsMu.Lock()
+	ss, ok := n.activeStreams[dst]
+	n.streamsMu.Unlock()
+
+	if ok {
+		ss.mu.Lock()
+		err := binary.Write(ss.stream, binary.LittleEndian, uint16(plen))
+		if err == nil {
+			_, err = ss.stream.Write(packet[:plen])
+			if err == nil {
+				err = ss.stream.SetWriteDeadline(time.Now().Add(25 * time.Second))
+			}
+		}
+		ss.mu.Unlock()
+
+		if err == nil {
+			return
+		}
+		ss.stream.Close()
+		n.streamsMu.Lock()
+		delete(n.activeStreams, dst)
+		n.streamsMu.Unlock()
+	}
+
+	stream, err := n.host.NewStream(n.ctx, dst, p2p.Protocol)
+	if err != nil {
+		logger.With(zap.String("dst", dst.String()), zap.Error(err)).Error("Failed to open stream")
+		go p2p.Rediscover()
+		return
+	}
+	_ = stream.SetWriteDeadline(time.Now().Add(25 * time.Second))
+
+	err = binary.Write(stream, binary.LittleEndian, uint16(plen))
+	if err != nil {
+		stream.Close()
+		return
+	}
+	_, err = stream.Write(packet[:plen])
+	if err != nil {
+		stream.Close()
+		return
+	}
+
+	n.streamsMu.Lock()
+	n.activeStreams[dst] = &sharedStream{stream: stream}
+	n.streamsMu.Unlock()
+}
+
+// passthroughGater allows all connections. On Android, the VpnService routing
+// prevents recursion (tunnel traffic going back into the VPN), so the
+// netlink-based RecursionGater from desktop is unnecessary.
+type passthroughGater struct{}
+
+func (passthroughGater) InterceptPeerDial(_ peer.ID) bool { return true }
+func (passthroughGater) InterceptAddrDial(_ peer.ID, _ ma.Multiaddr) bool {
+	return true
+}
+func (passthroughGater) InterceptAccept(_ network.ConnMultiaddrs) bool { return true }
+func (passthroughGater) InterceptSecured(_ network.Direction, _ peer.ID, _ network.ConnMultiaddrs) bool {
+	return true
+}
+func (passthroughGater) InterceptUpgraded(_ network.Conn) (bool, control.DisconnectReason) {
+	return true, 0
+}