[client] Refactor/iface pkg (#2646)

Refactor the flat code structure

client/iface/bind/udp_muxed_conn.go

@@ -0,0 +1,233 @@
+package bind
+
+/*
+ Most of this code was copied from https://github.com/pion/ice and modified to fulfill NetBird's requirements
+*/
+
+import (
+	"encoding/binary"
+	"io"
+	"net"
+	"sync"
+	"time"
+
+	"github.com/pion/logging"
+	"github.com/pion/transport/v3/packetio"
+)
+
+type udpMuxedConnParams struct {
+	Mux       *UDPMuxDefault
+	AddrPool  *sync.Pool
+	Key       string
+	LocalAddr net.Addr
+	Logger    logging.LeveledLogger
+}
+
+// udpMuxedConn represents a logical packet conn for a single remote as identified by ufrag
+type udpMuxedConn struct {
+	params *udpMuxedConnParams
+	// remote addresses that we have sent to on this conn
+	addresses []string
+
+	// channel holding incoming packets
+	buf        *packetio.Buffer
+	closedChan chan struct{}
+	closeOnce  sync.Once
+	mu         sync.Mutex
+}
+
+func newUDPMuxedConn(params *udpMuxedConnParams) *udpMuxedConn {
+	p := &udpMuxedConn{
+		params:     params,
+		buf:        packetio.NewBuffer(),
+		closedChan: make(chan struct{}),
+	}
+
+	return p
+}
+
+func (c *udpMuxedConn) ReadFrom(b []byte) (n int, rAddr net.Addr, err error) {
+	buf := c.params.AddrPool.Get().(*bufferHolder) //nolint:forcetypeassert
+	defer c.params.AddrPool.Put(buf)
+
+	// read address
+	total, err := c.buf.Read(buf.buf)
+	if err != nil {
+		return 0, nil, err
+	}
+
+	dataLen := int(binary.LittleEndian.Uint16(buf.buf[:2]))
+	if dataLen > total || dataLen > len(b) {
+		return 0, nil, io.ErrShortBuffer
+	}
+
+	// read data and then address
+	offset := 2
+	copy(b, buf.buf[offset:offset+dataLen])
+	offset += dataLen
+
+	// read address len & decode address
+	addrLen := int(binary.LittleEndian.Uint16(buf.buf[offset : offset+2]))
+	offset += 2
+
+	if rAddr, err = decodeUDPAddr(buf.buf[offset : offset+addrLen]); err != nil {
+		return 0, nil, err
+	}
+
+	return dataLen, rAddr, nil
+}
+
+func (c *udpMuxedConn) WriteTo(buf []byte, rAddr net.Addr) (n int, err error) {
+	if c.isClosed() {
+		return 0, io.ErrClosedPipe
+	}
+	// each time we write to a new address, we'll register it with the mux
+	addr := rAddr.String()
+	if !c.containsAddress(addr) {
+		c.addAddress(addr)
+	}
+
+	return c.params.Mux.writeTo(buf, rAddr)
+}
+
+func (c *udpMuxedConn) LocalAddr() net.Addr {
+	return c.params.LocalAddr
+}
+
+func (c *udpMuxedConn) SetDeadline(tm time.Time) error {
+	return nil
+}
+
+func (c *udpMuxedConn) SetReadDeadline(tm time.Time) error {
+	return nil
+}
+
+func (c *udpMuxedConn) SetWriteDeadline(tm time.Time) error {
+	return nil
+}
+
+func (c *udpMuxedConn) CloseChannel() <-chan struct{} {
+	return c.closedChan
+}
+
+func (c *udpMuxedConn) Close() error {
+	var err error
+	c.closeOnce.Do(func() {
+		err = c.buf.Close()
+		close(c.closedChan)
+	})
+	return err
+}
+
+func (c *udpMuxedConn) isClosed() bool {
+	select {
+	case <-c.closedChan:
+		return true
+	default:
+		return false
+	}
+}
+
+func (c *udpMuxedConn) getAddresses() []string {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	addresses := make([]string, len(c.addresses))
+	copy(addresses, c.addresses)
+	return addresses
+}
+
+func (c *udpMuxedConn) addAddress(addr string) {
+	c.mu.Lock()
+	c.addresses = append(c.addresses, addr)
+	c.mu.Unlock()
+
+	// map it on mux
+	c.params.Mux.registerConnForAddress(c, addr)
+}
+
+func (c *udpMuxedConn) containsAddress(addr string) bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	for _, a := range c.addresses {
+		if addr == a {
+			return true
+		}
+	}
+	return false
+}
+
+func (c *udpMuxedConn) writePacket(data []byte, addr *net.UDPAddr) error {
+	// write two packets, address and data
+	buf := c.params.AddrPool.Get().(*bufferHolder) //nolint:forcetypeassert
+	defer c.params.AddrPool.Put(buf)
+
+	// format of buffer | data len | data bytes | addr len | addr bytes |
+	if len(buf.buf) < len(data)+maxAddrSize {
+		return io.ErrShortBuffer
+	}
+	// data len
+	binary.LittleEndian.PutUint16(buf.buf, uint16(len(data)))
+	offset := 2
+
+	// data
+	copy(buf.buf[offset:], data)
+	offset += len(data)
+
+	// write address first, leaving room for its length
+	n, err := encodeUDPAddr(addr, buf.buf[offset+2:])
+	if err != nil {
+		return err
+	}
+	total := offset + n + 2
+
+	// address len
+	binary.LittleEndian.PutUint16(buf.buf[offset:], uint16(n))
+
+	if _, err := c.buf.Write(buf.buf[:total]); err != nil {
+		return err
+	}
+	return nil
+}
+
+func encodeUDPAddr(addr *net.UDPAddr, buf []byte) (int, error) {
+	ipData, err := addr.IP.MarshalText()
+	if err != nil {
+		return 0, err
+	}
+	total := 2 + len(ipData) + 2 + len(addr.Zone)
+	if total > len(buf) {
+		return 0, io.ErrShortBuffer
+	}
+
+	binary.LittleEndian.PutUint16(buf, uint16(len(ipData)))
+	offset := 2
+	n := copy(buf[offset:], ipData)
+	offset += n
+	binary.LittleEndian.PutUint16(buf[offset:], uint16(addr.Port))
+	offset += 2
+	copy(buf[offset:], addr.Zone)
+	return total, nil
+}
+
+func decodeUDPAddr(buf []byte) (*net.UDPAddr, error) {
+	addr := net.UDPAddr{}
+
+	offset := 0
+	ipLen := int(binary.LittleEndian.Uint16(buf[:2]))
+	offset += 2
+	// basic bounds checking
+	if ipLen+offset > len(buf) {
+		return nil, io.ErrShortBuffer
+	}
+	if err := addr.IP.UnmarshalText(buf[offset : offset+ipLen]); err != nil {
+		return nil, err
+	}
+	offset += ipLen
+	addr.Port = int(binary.LittleEndian.Uint16(buf[offset : offset+2]))
+	offset += 2
+	zone := make([]byte, len(buf[offset:]))
+	copy(zone, buf[offset:])
+	addr.Zone = string(zone)
+
+	return &addr, nil
+}