Alex X
436 lines
8.2 KiB
Go
436 lines
8.2 KiB
Go
package cs2
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import (
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"bufio"
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"encoding/binary"
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"fmt"
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"io"
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"net"
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"sync"
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"sync/atomic"
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"time"
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)
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func Dial(host, transport string) (*Conn, error) {
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conn, err := handshake(host, transport)
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if err != nil {
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return nil, err
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}
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_, isTCP := conn.(*tcpConn)
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c := &Conn{
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conn: conn,
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isTCP: isTCP,
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rawCh0: make(chan []byte, 10),
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rawCh2: make(chan []byte, 100),
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}
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go c.worker()
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return c, nil
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}
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type Conn struct {
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conn net.Conn
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isTCP bool
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err error
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seqCh0 uint16
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seqCh3 uint16
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rawCh0 chan []byte
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rawCh2 chan []byte
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cmdMu sync.Mutex
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cmdAck func()
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}
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const (
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magic = 0xF1
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magicDrw = 0xD1
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msgLanSearch = 0x30
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msgPunchPkt = 0x41
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msgP2PRdyUDP = 0x42
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msgP2PRdyTCP = 0x43
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msgDrw = 0xD0
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msgDrwAck = 0xD1
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msgPing = 0xE0
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msgPong = 0xE1
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msgClose = 0xF1
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)
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func handshake(host, transport string) (net.Conn, error) {
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conn, err := newUDPConn(host, 32108)
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if err != nil {
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return nil, err
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}
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_ = conn.SetDeadline(time.Now().Add(5 * time.Second))
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req := []byte{magic, msgLanSearch, 0, 0}
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res, err := conn.(*udpConn).WriteUntil(req, func(res []byte) bool {
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return res[1] == msgPunchPkt
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})
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if err != nil {
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_ = conn.Close()
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return nil, err
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}
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var msgUDP, msgTCP byte
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if transport == "" || transport == "udp" {
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msgUDP = msgP2PRdyUDP
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}
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if transport == "" || transport == "tcp" {
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msgTCP = msgP2PRdyTCP
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}
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res, err = conn.(*udpConn).WriteUntil(res, func(res []byte) bool {
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return res[1] == msgUDP || res[1] == msgTCP
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})
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if err != nil {
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_ = conn.Close()
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return nil, err
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}
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_ = conn.SetDeadline(time.Time{})
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if res[1] == msgTCP {
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_ = conn.Close()
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//host := fmt.Sprintf("%d.%d.%d.%d:%d", b[31], b[30], b[29], b[28], uint16(b[27])<<8|uint16(b[26]))
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return newTCPConn(conn.RemoteAddr().String())
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}
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return conn, nil
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}
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func (c *Conn) worker() {
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defer func() {
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close(c.rawCh0)
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close(c.rawCh2)
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}()
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chAck := make([]uint16, 4) // only for UDP
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buf := make([]byte, 1200)
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var ch2WaitSize int
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var ch2WaitData []byte
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var keepaliveTS time.Time
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for {
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n, err := c.conn.Read(buf)
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if err != nil {
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c.err = fmt.Errorf("%s: %w", "cs2", err)
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return
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}
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switch buf[1] {
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case msgDrw:
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ch := buf[5]
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if c.isTCP {
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// For TCP we should using ping/pong.
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if now := time.Now(); now.After(keepaliveTS) {
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_, _ = c.conn.Write([]byte{magic, msgPing, 0, 0})
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keepaliveTS = now.Add(5 * time.Second)
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}
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} else {
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// For UDP we should using ack.
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seqHI := buf[6]
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seqLO := buf[7]
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if chAck[ch] != uint16(seqHI)<<8|uint16(seqLO) {
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continue
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}
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chAck[ch]++
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ack := []byte{magic, msgDrwAck, 0, 6, magicDrw, ch, 0, 1, seqHI, seqLO}
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_, _ = c.conn.Write(ack)
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}
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switch ch {
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case 0:
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select {
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case c.rawCh0 <- buf[12:]:
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default:
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}
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continue
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case 2:
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ch2WaitData = append(ch2WaitData, buf[8:n]...)
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for len(ch2WaitData) > 4 {
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if ch2WaitSize == 0 {
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ch2WaitSize = int(binary.BigEndian.Uint32(ch2WaitData))
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ch2WaitData = ch2WaitData[4:]
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}
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if ch2WaitSize <= len(ch2WaitData) {
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select {
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case c.rawCh2 <- ch2WaitData[:ch2WaitSize]:
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default:
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c.err = fmt.Errorf("%s: media queue is full", "cs2")
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return
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}
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ch2WaitData = ch2WaitData[ch2WaitSize:]
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ch2WaitSize = 0
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} else {
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break
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}
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}
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continue
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}
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case msgPing:
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_, _ = c.conn.Write([]byte{magic, msgPong, 0, 0})
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continue
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case msgPong, msgP2PRdyUDP, msgP2PRdyTCP, msgClose:
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continue // skip it
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case msgDrwAck: // only for UDP
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if c.cmdAck != nil {
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c.cmdAck()
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}
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continue
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}
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fmt.Printf("%s: unknown msg: %x\n", "cs2", buf[:n])
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}
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}
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func (c *Conn) Protocol() string {
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if c.isTCP {
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return "cs2+tcp"
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}
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return "cs2+udp"
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}
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func (c *Conn) Version() string {
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return "CS2"
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}
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func (c *Conn) RemoteAddr() net.Addr {
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return c.conn.RemoteAddr()
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}
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func (c *Conn) SetDeadline(t time.Time) error {
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return c.conn.SetDeadline(t)
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}
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func (c *Conn) Close() error {
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return c.conn.Close()
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}
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func (c *Conn) Error() error {
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if c.err != nil {
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return c.err
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}
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return io.EOF
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}
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func (c *Conn) ReadCommand() (cmd uint32, data []byte, err error) {
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buf, ok := <-c.rawCh0
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if !ok {
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return 0, nil, c.Error()
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}
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return binary.LittleEndian.Uint32(buf), buf[4:], nil
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}
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func (c *Conn) WriteCommand(cmd uint32, data []byte) error {
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c.cmdMu.Lock()
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defer c.cmdMu.Unlock()
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req := marshalCmd(0, c.seqCh0, cmd, data)
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c.seqCh0++
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if c.isTCP {
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_, err := c.conn.Write(req)
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return err
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}
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var repeat atomic.Int32
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repeat.Store(5)
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timeout := time.NewTicker(time.Second)
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defer timeout.Stop()
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c.cmdAck = func() {
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repeat.Store(0)
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timeout.Reset(1)
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}
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for {
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if _, err := c.conn.Write(req); err != nil {
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return err
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}
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<-timeout.C
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r := repeat.Add(-1)
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if r < 0 {
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return nil
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}
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if r == 0 {
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return fmt.Errorf("%s: can't send command %d", "cs2", cmd)
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}
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}
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}
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func (c *Conn) ReadPacket() (hdr, payload []byte, err error) {
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data, ok := <-c.rawCh2
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if !ok {
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return nil, nil, c.Error()
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}
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return data[:32], data[32:], nil
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}
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func (c *Conn) WritePacket(hdr, payload []byte) error {
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const offset = 12
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n := 32 + uint32(len(payload))
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req := make([]byte, n+offset)
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req[0] = magic
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req[1] = msgDrw
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binary.BigEndian.PutUint16(req[2:], uint16(n+8))
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req[4] = magicDrw
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req[5] = 3 // channel
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binary.BigEndian.PutUint16(req[6:], c.seqCh3)
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c.seqCh3++
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binary.BigEndian.PutUint32(req[8:], n)
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copy(req[offset:], hdr)
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copy(req[offset+32:], payload)
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_, err := c.conn.Write(req)
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return err
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}
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func marshalCmd(channel byte, seq uint16, cmd uint32, payload []byte) []byte {
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size := len(payload)
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req := make([]byte, 4+4+4+4+size)
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// 1. message header (4 bytes)
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req[0] = magic
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req[1] = msgDrw
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binary.BigEndian.PutUint16(req[2:], uint16(4+4+4+size))
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// 2. drw? header (4 bytes)
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req[4] = magicDrw
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req[5] = channel
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binary.BigEndian.PutUint16(req[6:], seq)
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// 3. payload size (4 bytes)
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binary.BigEndian.PutUint32(req[8:], uint32(4+size))
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// 4. payload command (4 bytes)
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binary.BigEndian.PutUint32(req[12:], cmd)
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// 5. payload
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copy(req[16:], payload)
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return req
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}
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func newUDPConn(host string, port int) (net.Conn, error) {
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// We using raw net.UDPConn, because RemoteAddr should be changed during handshake.
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conn, err := net.ListenUDP("udp", nil)
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if err != nil {
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return nil, err
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}
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addr, err := net.ResolveUDPAddr("udp", host)
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if err != nil {
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addr = &net.UDPAddr{IP: net.ParseIP(host), Port: port}
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}
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return &udpConn{UDPConn: conn, addr: addr}, nil
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}
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type udpConn struct {
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*net.UDPConn
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addr *net.UDPAddr
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}
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func (c *udpConn) Read(p []byte) (n int, err error) {
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var addr *net.UDPAddr
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for {
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n, addr, err = c.UDPConn.ReadFromUDP(p)
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if err != nil {
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return 0, err
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}
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if string(addr.IP) == string(c.addr.IP) || n >= 8 {
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return
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}
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}
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}
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func (c *udpConn) Write(req []byte) (n int, err error) {
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//log.Printf("-> %x", req)
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return c.UDPConn.WriteToUDP(req, c.addr)
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}
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func (c *udpConn) RemoteAddr() net.Addr {
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return c.addr
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}
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func (c *udpConn) WriteUntil(req []byte, ok func(res []byte) bool) ([]byte, error) {
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var t *time.Timer
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t = time.AfterFunc(1, func() {
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if _, err := c.Write(req); err == nil && t != nil {
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t.Reset(time.Second)
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}
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})
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defer t.Stop()
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buf := make([]byte, 1200)
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for {
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n, addr, err := c.UDPConn.ReadFromUDP(buf)
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if err != nil {
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return nil, err
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}
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if string(addr.IP) != string(c.addr.IP) || n < 16 {
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continue // skip messages from another IP
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}
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if ok(buf[:n]) {
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c.addr.Port = addr.Port
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return buf[:n], nil
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}
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}
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}
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func newTCPConn(addr string) (net.Conn, error) {
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conn, err := net.DialTimeout("tcp", addr, 3*time.Second)
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if err != nil {
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return nil, err
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}
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return &tcpConn{conn.(*net.TCPConn), bufio.NewReader(conn)}, nil
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}
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type tcpConn struct {
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*net.TCPConn
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rd *bufio.Reader
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}
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func (c *tcpConn) Read(p []byte) (n int, err error) {
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tmp := make([]byte, 8)
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if _, err = io.ReadFull(c.rd, tmp); err != nil {
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return
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}
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n = int(binary.BigEndian.Uint16(tmp))
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if len(p) < n {
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return 0, fmt.Errorf("tcp: buffer too small")
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}
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_, err = io.ReadFull(c.rd, p[:n])
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//log.Printf("<- %x%x", tmp, p[:n])
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return
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}
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func (c *tcpConn) Write(req []byte) (n int, err error) {
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n = len(req)
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buf := make([]byte, 8+n)
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binary.BigEndian.PutUint16(buf, uint16(n))
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buf[2] = 0x68
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copy(buf[8:], req)
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//log.Printf("-> %x", buf)
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_, err = c.TCPConn.Write(buf)
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return
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}
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