[client] Refactor/iface pkg (#2646)

Refactor the flat code structure

client/iface/netstack/dialer.go

@@ -0,0 +1,32 @@
+package netstack
+
+import (
+	"context"
+	"net"
+
+	log "github.com/sirupsen/logrus"
+	"golang.zx2c4.com/wireguard/tun/netstack"
+)
+
+type Dialer interface {
+	Dial(ctx context.Context, network, addr string) (net.Conn, error)
+}
+
+type NSDialer struct {
+	net *netstack.Net
+}
+
+func NewNSDialer(net *netstack.Net) *NSDialer {
+	return &NSDialer{
+		net: net,
+	}
+}
+
+func (d *NSDialer) Dial(ctx context.Context, network, addr string) (net.Conn, error) {
+	log.Debugf("dialing %s %s", network, addr)
+	conn, err := d.net.Dial(network, addr)
+	if err != nil {
+		log.Debugf("failed to deal connection: %s", err)
+	}
+	return conn, err
+}

client/iface/netstack/env.go

@@ -0,0 +1,33 @@
+package netstack
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+
+	log "github.com/sirupsen/logrus"
+)
+
+// IsEnabled todo: move these function to cmd layer
+func IsEnabled() bool {
+	return os.Getenv("NB_USE_NETSTACK_MODE") == "true"
+}
+
+func ListenAddr() string {
+	sPort := os.Getenv("NB_SOCKS5_LISTENER_PORT")
+	port, err := strconv.Atoi(sPort)
+	if err != nil {
+		log.Warnf("invalid socks5 listener port, unable to convert it to int, falling back to default: %d", DefaultSocks5Port)
+		return listenAddr(DefaultSocks5Port)
+	}
+	if port < 1 || port > 65535 {
+		log.Warnf("invalid socks5 listener port, it should be in the range 1-65535, falling back to default: %d", DefaultSocks5Port)
+		return listenAddr(DefaultSocks5Port)
+	}
+
+	return listenAddr(port)
+}
+
+func listenAddr(port int) string {
+	return fmt.Sprintf("0.0.0.0:%d", port)
+}

client/iface/netstack/proxy.go

@@ -0,0 +1,65 @@
+package netstack
+
+import (
+	"net"
+
+	"github.com/things-go/go-socks5"
+
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	DefaultSocks5Port = 1080
+)
+
+// Proxy todo close server
+type Proxy struct {
+	server *socks5.Server
+
+	listener net.Listener
+	closed   bool
+}
+
+func NewSocks5(dialer Dialer) (*Proxy, error) {
+	server := socks5.NewServer(
+		socks5.WithDial(dialer.Dial),
+	)
+
+	return &Proxy{
+		server: server,
+	}, nil
+}
+
+func (s *Proxy) ListenAndServe(addr string) error {
+	listener, err := net.Listen("tcp", addr)
+	if err != nil {
+		log.Errorf("failed to create listener for socks5 proxy: %s", err)
+		return err
+	}
+	s.listener = listener
+
+	for {
+		conn, err := listener.Accept()
+		if err != nil {
+			if s.closed {
+				return nil
+			}
+			return err
+		}
+
+		go func() {
+			if err := s.server.ServeConn(conn); err != nil {
+				log.Errorf("failed to serve a connection: %s", err)
+			}
+		}()
+	}
+}
+
+func (s *Proxy) Close() error {
+	if s.listener == nil {
+		return nil
+	}
+
+	s.closed = true
+	return s.listener.Close()
+}

client/iface/netstack/tun.go

@@ -0,0 +1,74 @@
+package netstack
+
+import (
+	"net/netip"
+
+	log "github.com/sirupsen/logrus"
+	"golang.zx2c4.com/wireguard/tun"
+	"golang.zx2c4.com/wireguard/tun/netstack"
+)
+
+type NetStackTun struct { //nolint:revive
+	address       string
+	mtu           int
+	listenAddress string
+
+	proxy  *Proxy
+	tundev tun.Device
+}
+
+func NewNetStackTun(listenAddress string, address string, mtu int) *NetStackTun {
+	return &NetStackTun{
+		address:       address,
+		mtu:           mtu,
+		listenAddress: listenAddress,
+	}
+}
+
+func (t *NetStackTun) Create() (tun.Device, error) {
+	nsTunDev, tunNet, err := netstack.CreateNetTUN(
+		[]netip.Addr{netip.MustParseAddr(t.address)},
+		[]netip.Addr{},
+		t.mtu)
+	if err != nil {
+		return nil, err
+	}
+	t.tundev = nsTunDev
+
+	dialer := NewNSDialer(tunNet)
+	t.proxy, err = NewSocks5(dialer)
+	if err != nil {
+		_ = t.tundev.Close()
+		return nil, err
+	}
+
+	go func() {
+		err := t.proxy.ListenAndServe(t.listenAddress)
+		if err != nil {
+			log.Errorf("error in socks5 proxy serving: %s", err)
+		}
+	}()
+
+	return nsTunDev, nil
+}
+
+func (t *NetStackTun) Close() error {
+	var err error
+	if t.proxy != nil {
+		pErr := t.proxy.Close()
+		if pErr != nil {
+			log.Errorf("failed to close socks5 proxy: %s", pErr)
+			err = pErr
+		}
+	}
+
+	if t.tundev != nil {
+		dErr := t.tundev.Close()
+		if dErr != nil {
+			log.Errorf("failed to close netstack tun device: %s", dErr)
+			err = dErr
+		}
+	}
+
+	return err
+}