// dial tcp with tcp fastopen
// 第一个包体积不要太大,需要小于一定数量,否则会被吃掉(正确性问题),
// 如果过大,此处会在连接时发送前一部分,连接后又发送一部分
func TfoDial(nextAddr string, data []byte) (conn net.Conn, err error) {
s, err := unix.Socket(unix.AF_INET, unix.SOCK_STREAM, 0)
if err != nil {
return nil, err
}
defer unix.Close(s)
sa, err := kmgUnix.IPv4TcpAddrToUnixSocksAddr(nextAddr)
if err != nil {
return nil, err
}
if len(data) <= tfoFirstSize {
err = unix.Sendto(s, data, unix.MSG_FASTOPEN, sa)
if err != nil {
return
}
} else {
err = unix.Sendto(s, data[:tfoFirstSize], unix.MSG_FASTOPEN, sa)
if err != nil {
return
}
}
f := os.NewFile(uintptr(s), "TFODial")
defer f.Close()
conn, err = net.FileConn(f)
if err != nil {
return
}
if len(data) > tfoFirstSize {
_, err = conn.Write(data[tfoFirstSize:])
if err != nil {
return nil, err
}
}
return conn, nil
}
func (d *afpacket) Write(from ethernet.Frame) (err error) {
copy(d.sockaddrLL.Addr[:6], []byte(from.Destination()))
err = unix.Sendto(d.fd, []byte(from), 0, d.sockaddrLL)
if err != nil {
return
}
return
}
func (pc *packetSock) Write(packet []byte) error {
lladdr := unix.SockaddrLinklayer{
Ifindex: pc.ifindex,
Protocol: swap16(unix.ETH_P_IP),
Halen: uint8(len(bcastMAC)),
}
copy(lladdr.Addr[:], bcastMAC)
pkt := make([]byte, minIPHdrLen+udpHdrLen+len(packet))
fillIPHdr(pkt[0:minIPHdrLen], udpHdrLen+uint16(len(packet)))
fillUDPHdr(pkt[minIPHdrLen:minIPHdrLen+udpHdrLen], uint16(len(packet)))
// payload
copy(pkt[minIPHdrLen+udpHdrLen:len(pkt)], packet)
return unix.Sendto(pc.fd, pkt, 0, &lladdr)
}
// TfoDial dials to addr using tcp protocol with fast open option set,
// addr should be in the form of "addr:port",
// the data is sent along with the first syn packet of tcp handshake.
// It returns a established connection and an error if any.
func tfoDial(addr string, data []byte) (conn net.Conn, err error) {
fd, err := unix.Socket(unix.AF_INET, unix.SOCK_STREAM, 0)
if err != nil {
return
}
defer unix.Close(fd)
sa, err := tcpAddrToSockaddr(addr)
if err != nil {
return
}
err = unix.Sendto(fd, data, unix.MSG_FASTOPEN, sa)
if err != nil {
return
}
f := os.NewFile(uintptr(fd), "TFODial")
defer f.Close()
return net.FileConn(f)
}