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server/vendor/github.com/pion/turn/v2/stun_conn.go

@@ -0,0 +1,127 @@
+// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+package turn
+
+import (
+	"encoding/binary"
+	"errors"
+	"net"
+	"time"
+
+	"github.com/pion/stun"
+	"github.com/pion/turn/v2/internal/proto"
+)
+
+var (
+	errInvalidTURNFrame    = errors.New("data is not a valid TURN frame, no STUN or ChannelData found")
+	errIncompleteTURNFrame = errors.New("data contains incomplete STUN or TURN frame")
+)
+
+// STUNConn wraps a net.Conn and implements
+// net.PacketConn by being STUN aware and
+// packetizing the stream
+type STUNConn struct {
+	nextConn net.Conn
+	buff     []byte
+}
+
+const (
+	stunHeaderSize = 20
+
+	channelDataLengthSize = 2
+	channelDataNumberSize = channelDataLengthSize
+	channelDataHeaderSize = channelDataLengthSize + channelDataNumberSize
+	channelDataPadding    = 4
+)
+
+// Given a buffer give the last offset of the TURN frame
+// If the buffer isn't a valid STUN or ChannelData packet
+// or the length doesn't match return false
+func consumeSingleTURNFrame(p []byte) (int, error) {
+	// Too short to determine if ChannelData or STUN
+	if len(p) < 9 {
+		return 0, errIncompleteTURNFrame
+	}
+
+	var datagramSize uint16
+	switch {
+	case stun.IsMessage(p):
+		datagramSize = binary.BigEndian.Uint16(p[2:4]) + stunHeaderSize
+	case proto.ChannelNumber(binary.BigEndian.Uint16(p[0:2])).Valid():
+		datagramSize = binary.BigEndian.Uint16(p[channelDataNumberSize:channelDataHeaderSize])
+		if paddingOverflow := (datagramSize + channelDataPadding) % channelDataPadding; paddingOverflow != 0 {
+			datagramSize = (datagramSize + channelDataPadding) - paddingOverflow
+		}
+
+		datagramSize += channelDataHeaderSize
+	case len(p) < stunHeaderSize:
+		return 0, errIncompleteTURNFrame
+	default:
+		return 0, errInvalidTURNFrame
+	}
+
+	if len(p) < int(datagramSize) {
+		return 0, errIncompleteTURNFrame
+	}
+
+	return int(datagramSize), nil
+}
+
+// ReadFrom implements ReadFrom from net.PacketConn
+func (s *STUNConn) ReadFrom(p []byte) (n int, addr net.Addr, err error) {
+	// First pass any buffered data from previous reads
+	n, err = consumeSingleTURNFrame(s.buff)
+	if errors.Is(err, errInvalidTURNFrame) {
+		return 0, nil, err
+	} else if err == nil {
+		copy(p, s.buff[:n])
+		s.buff = s.buff[n:]
+
+		return n, s.nextConn.RemoteAddr(), nil
+	}
+
+	// Then read from the nextConn, appending to our buff
+	n, err = s.nextConn.Read(p)
+	if err != nil {
+		return 0, nil, err
+	}
+
+	s.buff = append(s.buff, append([]byte{}, p[:n]...)...)
+	return s.ReadFrom(p)
+}
+
+// WriteTo implements WriteTo from net.PacketConn
+func (s *STUNConn) WriteTo(p []byte, _ net.Addr) (n int, err error) {
+	return s.nextConn.Write(p)
+}
+
+// Close implements Close from net.PacketConn
+func (s *STUNConn) Close() error {
+	return s.nextConn.Close()
+}
+
+// LocalAddr implements LocalAddr from net.PacketConn
+func (s *STUNConn) LocalAddr() net.Addr {
+	return s.nextConn.LocalAddr()
+}
+
+// SetDeadline implements SetDeadline from net.PacketConn
+func (s *STUNConn) SetDeadline(t time.Time) error {
+	return s.nextConn.SetDeadline(t)
+}
+
+// SetReadDeadline implements SetReadDeadline from net.PacketConn
+func (s *STUNConn) SetReadDeadline(t time.Time) error {
+	return s.nextConn.SetReadDeadline(t)
+}
+
+// SetWriteDeadline implements SetWriteDeadline from net.PacketConn
+func (s *STUNConn) SetWriteDeadline(t time.Time) error {
+	return s.nextConn.SetWriteDeadline(t)
+}
+
+// NewSTUNConn creates a STUNConn
+func NewSTUNConn(nextConn net.Conn) *STUNConn {
+	return &STUNConn{nextConn: nextConn}
+}