Merge pull request #36 from smediainfo/feat/host-socket-protect

feat(mobile): add host socket protector (SetProtect) for tun/VPN hosts

internal/client/dnsdial/doh.go

@@ -21,6 +21,7 @@ import (
 	"github.com/miekg/dns"
 
 	"github.com/samosvalishe/free-turn-proxy/internal/logx"
+	"github.com/samosvalishe/free-turn-proxy/internal/netctl"
 
 	// встроенные Mozilla CA roots для CGO_ENABLED=0 сборок (Android).
 	_ "golang.org/x/crypto/x509roots/fallback"
@@ -98,7 +99,7 @@ func newBootstrapTransport(endpoints []DohEndpoint) *http.Transport {
 	for _, ep := range endpoints {
 		bootstrap[ep.Hostname] = ep.BootstrapIPs
 	}
-	dialer := &net.Dialer{Timeout: dohDialerTimeout, KeepAlive: dohDialerKeepAlive}
+	dialer := &net.Dialer{Timeout: dohDialerTimeout, KeepAlive: dohDialerKeepAlive, Control: netctl.Apply}
 
 	return &http.Transport{
 		MaxIdleConns:        8,
@@ -440,6 +441,7 @@ func newAppDialer(dial dialFunc) net.Dialer {
 		Timeout:   appDialerTimeout,
 		KeepAlive: appDialerKeepAlive,
 		Resolver:  &net.Resolver{PreferGo: true, Dial: dial},
+		Control:   netctl.Apply,
 	}
 }
 

internal/netconn/netconn.go

@@ -12,6 +12,7 @@ import (
 	"time"
 
 	"github.com/pion/transport/v4"
+	"github.com/samosvalishe/free-turn-proxy/internal/netctl"
 )
 
 // DirectNet реализует transport.Net через стандартный net.
@@ -34,32 +35,84 @@ type directTCPListener struct {
 	*net.TCPListener
 }
 
+// All socket-creating methods route through a net.Dialer / net.ListenConfig
+// carrying netctl.Apply as Control so the host can protect each fd from the
+// VPN tunnel. (net.DialUDP / net.ListenUDP take no Control, so we go via
+// Dialer/ListenConfig and type-assert back to the concrete UDP/TCP conn.)
 func (DirectNet) ListenPacket(network string, address string) (net.PacketConn, error) {
-	return net.ListenPacket(network, address) //nolint:noctx
+	return (&net.ListenConfig{Control: netctl.Apply}).ListenPacket(context.Background(), network, address)
 }
 
 func (DirectNet) ListenUDP(network string, locAddr *net.UDPAddr) (transport.UDPConn, error) {
-	return net.ListenUDP(network, locAddr)
-}
-
-func (DirectNet) ListenTCP(network string, laddr *net.TCPAddr) (transport.TCPListener, error) {
-	listener, err := net.ListenTCP(network, laddr)
+	addr := ""
+	if locAddr != nil {
+		addr = locAddr.String()
+	}
+	pc, err := (&net.ListenConfig{Control: netctl.Apply}).ListenPacket(context.Background(), network, addr)
 	if err != nil {
 		return nil, err
 	}
-	return directTCPListener{listener}, nil
+	udp, ok := pc.(*net.UDPConn)
+	if !ok {
+		_ = pc.Close()
+		return nil, fmt.Errorf("netconn: expected *net.UDPConn, got %T", pc)
+	}
+	return udp, nil
+}
+
+func (DirectNet) ListenTCP(network string, laddr *net.TCPAddr) (transport.TCPListener, error) {
+	addr := ""
+	if laddr != nil {
+		addr = laddr.String()
+	}
+	l, err := (&net.ListenConfig{Control: netctl.Apply}).Listen(context.Background(), network, addr)
+	if err != nil {
+		return nil, err
+	}
+	tl, ok := l.(*net.TCPListener)
+	if !ok {
+		_ = l.Close()
+		return nil, fmt.Errorf("netconn: expected *net.TCPListener, got %T", l)
+	}
+	return directTCPListener{tl}, nil
 }
 
 func (DirectNet) Dial(network, address string) (net.Conn, error) {
-	return net.Dial(network, address) //nolint:noctx
+	return (&net.Dialer{Control: netctl.Apply}).Dial(network, address)
 }
 
 func (DirectNet) DialUDP(network string, laddr, raddr *net.UDPAddr) (transport.UDPConn, error) {
-	return net.DialUDP(network, laddr, raddr)
+	d := &net.Dialer{Control: netctl.Apply}
+	if laddr != nil {
+		d.LocalAddr = laddr
+	}
+	c, err := d.Dial(network, raddr.String())
+	if err != nil {
+		return nil, err
+	}
+	udp, ok := c.(*net.UDPConn)
+	if !ok {
+		_ = c.Close()
+		return nil, fmt.Errorf("netconn: expected *net.UDPConn, got %T", c)
+	}
+	return udp, nil
 }
 
 func (DirectNet) DialTCP(network string, laddr, raddr *net.TCPAddr) (transport.TCPConn, error) {
-	return net.DialTCP(network, laddr, raddr)
+	d := &net.Dialer{Control: netctl.Apply}
+	if laddr != nil {
+		d.LocalAddr = laddr
+	}
+	c, err := d.Dial(network, raddr.String())
+	if err != nil {
+		return nil, err
+	}
+	tcp, ok := c.(*net.TCPConn)
+	if !ok {
+		_ = c.Close()
+		return nil, fmt.Errorf("netconn: expected *net.TCPConn, got %T", c)
+	}
+	return tcp, nil
 }
 
 func (DirectNet) ResolveIPAddr(network, address string) (*net.IPAddr, error) {
@@ -87,10 +140,16 @@ func (DirectNet) InterfaceByName(name string) (*transport.Interface, error) {
 }
 
 func (DirectNet) CreateDialer(dialer *net.Dialer) transport.Dialer {
+	if dialer.Control == nil {
+		dialer.Control = netctl.Apply
+	}
 	return directDialer{Dialer: dialer}
 }
 
 func (DirectNet) CreateListenConfig(listenerConfig *net.ListenConfig) transport.ListenConfig {
+	if listenerConfig.Control == nil {
+		listenerConfig.Control = netctl.Apply
+	}
 	return directListenConfig{ListenConfig: listenerConfig}
 }
 

internal/netctl/netctl.go

@@ -0,0 +1,28 @@
+// Package netctl carries a process-global socket Control hook applied to every
+// OUTBOUND socket the vendored free-turn client opens. The host installs it so
+// those sockets are excluded from the VPN tunnel (Android VpnService.protect on
+// the raw fd) — without it the client's own TURN/VK/DNS traffic loops back into
+// the tunnel and hangs. This patch is local to our vendored copy: upstream has
+// no such hook, and the dialers it creates (netconn.DirectNet, dnsdial,
+// turndial) are routed through Apply below.
+package netctl
+
+import "syscall"
+
+var control func(network, address string, c syscall.RawConn) error
+
+// SetControl installs the per-socket protector. Call before the client starts.
+// nil (the default) makes Apply a no-op, so desktop builds are unaffected.
+func SetControl(fn func(network, address string, c syscall.RawConn) error) {
+	control = fn
+}
+
+// Apply is assigned as the Control func of every outbound net.Dialer /
+// net.ListenConfig in the vendored client. It reads `control` at dial time so
+// the host may register the protector before or after the client starts.
+func Apply(network, address string, c syscall.RawConn) error {
+	if control != nil {
+		return control(network, address, c)
+	}
+	return nil
+}

internal/transport/turndial/turndial.go

@@ -17,6 +17,7 @@ import (
 	"github.com/pion/logging"
 	"github.com/pion/turn/v5"
 	"github.com/samosvalishe/free-turn-proxy/internal/netconn"
+	"github.com/samosvalishe/free-turn-proxy/internal/netctl"
 	"github.com/samosvalishe/free-turn-proxy/internal/randx"
 )
 
@@ -83,10 +84,15 @@ func Open(ctx context.Context, cfg Config, peer *net.UDPAddr, user, pass, rawAdd
 		closeConn func() error
 	)
 	if cfg.TransportUDP {
-		c, derr := net.DialUDP("udp", nil, turnServerUDPAddr) //nolint:noctx
+		raw, derr := (&net.Dialer{Control: netctl.Apply}).Dial("udp", turnServerUDPAddr.String())
 		if derr != nil {
 			return nil, fmt.Errorf("dial TURN (udp): %w", derr)
 		}
+		c, ok := raw.(*net.UDPConn)
+		if !ok {
+			_ = raw.Close()
+			return nil, fmt.Errorf("turndial: expected *net.UDPConn, got %T", raw)
+		}
 		turnConn = &netconn.ConnectedUDPConn{UDPConn: c}
 		closeConn = c.Close
 	} else {

mobile/protect.go

@@ -0,0 +1,30 @@
+package mobile
+
+import (
+	"syscall"
+
+	"github.com/samosvalishe/free-turn-proxy/internal/netctl"
+)
+
+// Protector is implemented by the host to keep the client's own sockets out of
+// a VPN tunnel it is feeding. On Android that is VpnService.protect(fd); on
+// other tun-based hosts the equivalent. Without it the client's TURN / VK API /
+// DNS traffic is routed back into the tunnel and the connection deadlocks.
+type Protector interface {
+	// Protect is invoked once for every outbound socket the client opens, with
+	// the socket's raw file descriptor, before it connects.
+	Protect(fd int) bool
+}
+
+// SetProtect installs the host socket protector. Pass nil to clear it (the
+// default is a no-op, so desktop builds are unaffected). May be called before
+// or after Start; it is read at dial time.
+func SetProtect(p Protector) {
+	if p == nil {
+		netctl.SetControl(nil)
+		return
+	}
+	netctl.SetControl(func(_, _ string, c syscall.RawConn) error {
+		return c.Control(func(fd uintptr) { p.Protect(int(fd)) })
+	})
+}