Handle IPv6 candidates in userspace bind

client/iface/bind/dual_stack_conn.go

@@ -0,0 +1,153 @@
+package bind
+
+import (
+	"errors"
+	"net"
+	"time"
+
+	"github.com/hashicorp/go-multierror"
+
+	nberrors "github.com/netbirdio/netbird/client/errors"
+)
+
+var (
+	errNoIPv4Conn  = errors.New("no IPv4 connection available")
+	errNoIPv6Conn  = errors.New("no IPv6 connection available")
+	errInvalidAddr = errors.New("invalid address type")
+)
+
+// DualStackPacketConn is a composite PacketConn that can handle both IPv4 and IPv6
+type DualStackPacketConn struct {
+	ipv4Conn net.PacketConn
+	ipv6Conn net.PacketConn
+}
+
+// NewDualStackPacketConn creates a new dual-stack packet connection
+func NewDualStackPacketConn(ipv4Conn, ipv6Conn net.PacketConn) *DualStackPacketConn {
+	return &DualStackPacketConn{
+		ipv4Conn: ipv4Conn,
+		ipv6Conn: ipv6Conn,
+	}
+}
+
+// ReadFrom reads from both IPv4 and IPv6 connections
+func (d *DualStackPacketConn) ReadFrom(b []byte) (n int, addr net.Addr, err error) {
+	// Prefer IPv4 if available
+	if d.ipv4Conn != nil {
+		return d.ipv4Conn.ReadFrom(b)
+	}
+	if d.ipv6Conn != nil {
+		return d.ipv6Conn.ReadFrom(b)
+	}
+	return 0, nil, net.ErrClosed
+}
+
+// WriteTo writes to the appropriate connection based on the address type
+func (d *DualStackPacketConn) WriteTo(b []byte, addr net.Addr) (n int, err error) {
+	udpAddr, ok := addr.(*net.UDPAddr)
+	if !ok {
+		return 0, &net.OpError{
+			Op:   "write",
+			Net:  "udp",
+			Addr: addr,
+			Err:  errInvalidAddr,
+		}
+	}
+
+	if udpAddr.IP.To4() == nil {
+		if d.ipv6Conn != nil {
+			return d.ipv6Conn.WriteTo(b, addr)
+		}
+		return 0, &net.OpError{
+			Op:   "write",
+			Net:  "udp6",
+			Addr: addr,
+			Err:  errNoIPv6Conn,
+		}
+	}
+
+	if d.ipv4Conn != nil {
+		return d.ipv4Conn.WriteTo(b, addr)
+	}
+	return 0, &net.OpError{
+		Op:   "write",
+		Net:  "udp4",
+		Addr: addr,
+		Err:  errNoIPv4Conn,
+	}
+}
+
+// Close closes both connections
+func (d *DualStackPacketConn) Close() error {
+	var result *multierror.Error
+	if d.ipv4Conn != nil {
+		if err := d.ipv4Conn.Close(); err != nil {
+			result = multierror.Append(result, err)
+		}
+	}
+	if d.ipv6Conn != nil {
+		if err := d.ipv6Conn.Close(); err != nil {
+			result = multierror.Append(result, err)
+		}
+	}
+	return nberrors.FormatErrorOrNil(result)
+}
+
+// LocalAddr returns the local address of the IPv4 connection (for compatibility)
+func (d *DualStackPacketConn) LocalAddr() net.Addr {
+	if d.ipv4Conn != nil {
+		return d.ipv4Conn.LocalAddr()
+	}
+	if d.ipv6Conn != nil {
+		return d.ipv6Conn.LocalAddr()
+	}
+	return nil
+}
+
+// SetDeadline sets the deadline for both connections
+func (d *DualStackPacketConn) SetDeadline(t time.Time) error {
+	var result *multierror.Error
+	if d.ipv4Conn != nil {
+		if err := d.ipv4Conn.SetDeadline(t); err != nil {
+			result = multierror.Append(result, err)
+		}
+	}
+	if d.ipv6Conn != nil {
+		if err := d.ipv6Conn.SetDeadline(t); err != nil {
+			result = multierror.Append(result, err)
+		}
+	}
+	return nberrors.FormatErrorOrNil(result)
+}
+
+// SetReadDeadline sets the read deadline for both connections
+func (d *DualStackPacketConn) SetReadDeadline(t time.Time) error {
+	var result *multierror.Error
+	if d.ipv4Conn != nil {
+		if err := d.ipv4Conn.SetReadDeadline(t); err != nil {
+			result = multierror.Append(result, err)
+		}
+	}
+	if d.ipv6Conn != nil {
+		if err := d.ipv6Conn.SetReadDeadline(t); err != nil {
+			result = multierror.Append(result, err)
+		}
+	}
+	return nberrors.FormatErrorOrNil(result)
+}
+
+// SetWriteDeadline sets the write deadline for both connections
+func (d *DualStackPacketConn) SetWriteDeadline(t time.Time) error {
+	var result *multierror.Error
+	if d.ipv4Conn != nil {
+		if err := d.ipv4Conn.SetWriteDeadline(t); err != nil {
+			result = multierror.Append(result, err)
+		}
+	}
+	if d.ipv6Conn != nil {
+		if err := d.ipv6Conn.SetWriteDeadline(t); err != nil {
+			result = multierror.Append(result, err)
+		}
+	}
+	return nberrors.FormatErrorOrNil(result)
+}