[client] Close the remote conn in proxy (#2626)

Port the conn close call to eBPF proxy

client/internal/wgproxy/usp/proxy.go

@@ -0,0 +1,146 @@
+package usp
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"sync"
+
+	"github.com/hashicorp/go-multierror"
+	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/client/errors"
+)
+
+// WGUserSpaceProxy proxies
+type WGUserSpaceProxy struct {
+	localWGListenPort int
+	ctx               context.Context
+	cancel            context.CancelFunc
+
+	remoteConn net.Conn
+	localConn  net.Conn
+	closeMu    sync.Mutex
+	closed     bool
+}
+
+// NewWGUserSpaceProxy instantiate a user space WireGuard proxy. This is not a thread safe implementation
+func NewWGUserSpaceProxy(wgPort int) *WGUserSpaceProxy {
+	log.Debugf("Initializing new user space proxy with port %d", wgPort)
+	p := &WGUserSpaceProxy{
+		localWGListenPort: wgPort,
+	}
+	return p
+}
+
+// AddTurnConn start the proxy with the given remote conn
+func (p *WGUserSpaceProxy) AddTurnConn(ctx context.Context, remoteConn net.Conn) (net.Addr, error) {
+	p.ctx, p.cancel = context.WithCancel(ctx)
+
+	p.remoteConn = remoteConn
+
+	var err error
+	dialer := net.Dialer{}
+	p.localConn, err = dialer.DialContext(p.ctx, "udp", fmt.Sprintf(":%d", p.localWGListenPort))
+	if err != nil {
+		log.Errorf("failed dialing to local Wireguard port %s", err)
+		return nil, err
+	}
+
+	go p.proxyToRemote()
+	go p.proxyToLocal()
+
+	return p.localConn.LocalAddr(), err
+}
+
+// CloseConn close the localConn
+func (p *WGUserSpaceProxy) CloseConn() error {
+	if p.cancel == nil {
+		return fmt.Errorf("proxy not started")
+	}
+	return p.close()
+}
+
+func (p *WGUserSpaceProxy) close() error {
+	p.closeMu.Lock()
+	defer p.closeMu.Unlock()
+
+	// prevent double close
+	if p.closed {
+		return nil
+	}
+	p.closed = true
+
+	p.cancel()
+
+	var result *multierror.Error
+	if err := p.remoteConn.Close(); err != nil {
+		result = multierror.Append(result, fmt.Errorf("remote conn: %s", err))
+	}
+
+	if err := p.localConn.Close(); err != nil {
+		result = multierror.Append(result, fmt.Errorf("local conn: %s", err))
+	}
+	return errors.FormatErrorOrNil(result)
+}
+
+// proxyToRemote proxies from Wireguard to the RemoteKey
+func (p *WGUserSpaceProxy) proxyToRemote() {
+	defer func() {
+		if err := p.close(); err != nil {
+			log.Warnf("error in proxy to remote loop: %s", err)
+		}
+	}()
+
+	buf := make([]byte, 1500)
+	for p.ctx.Err() == nil {
+		n, err := p.localConn.Read(buf)
+		if err != nil {
+			if p.ctx.Err() != nil {
+				return
+			}
+			log.Debugf("failed to read from wg interface conn: %s", err)
+			return
+		}
+
+		_, err = p.remoteConn.Write(buf[:n])
+		if err != nil {
+			if p.ctx.Err() != nil {
+				return
+			}
+
+			log.Debugf("failed to write to remote conn: %s", err)
+			return
+		}
+	}
+}
+
+// proxyToLocal proxies from the Remote peer to local WireGuard
+func (p *WGUserSpaceProxy) proxyToLocal() {
+	defer func() {
+		if err := p.close(); err != nil {
+			log.Warnf("error in proxy to local loop: %s", err)
+		}
+	}()
+
+	buf := make([]byte, 1500)
+	for p.ctx.Err() == nil {
+		n, err := p.remoteConn.Read(buf)
+		if err != nil {
+			if p.ctx.Err() != nil {
+				return
+			}
+			log.Errorf("failed to read from remote conn: %s, %s", p.remoteConn.RemoteAddr(), err)
+			return
+		}
+
+		_, err = p.localConn.Write(buf[:n])
+		if err != nil {
+			if p.ctx.Err() != nil {
+				return
+			}
+			log.Debugf("failed to write to wg interface conn: %s", err)
+			continue
+		}
+	}
+}