client_datagram.go

package socks5

import "log"

func NewDatagramFromBytes(bb []byte) (*DatagramC, error) {
	n := len(bb)
	minl := 4
	if n < minl {
		return nil, ErrBadRequest
	}
	var addr []byte
	if bb[3] == ATYPIPv4 {
		minl += 4
		if n < minl {
			return nil, ErrBadRequest
		}
		addr = bb[minl-4 : minl]
	} else if bb[3] == ATYPIPv6 {
		minl += 16
		if n < minl {
			return nil, ErrBadRequest
		}
		addr = bb[minl-16 : minl]
	} else if bb[3] == ATYPDomain {
		minl += 1
		if n < minl {
			return nil, ErrBadRequest
		}
		l := bb[4]
		if l == 0 {
			return nil, ErrBadRequest
		}
		minl += int(l)
		if n < minl {
			return nil, ErrBadRequest
		}
		addr = bb[minl-int(l) : minl]
		addr = append([]byte{l}, addr...)
	} else {
		return nil, ErrBadRequest
	}
	minl += 2
	if n <= minl {
		return nil, ErrBadRequest
	}
	port := bb[minl-2 : minl]
	data := bb[minl:]
	d := &DatagramC{
		Rsv:     bb[0:2],
		Frag:    bb[2],
		Atyp:    bb[3],
		DstAddr: addr,
		DstPort: port,
		Data:    data,
	}
	if Debug {
		log.Printf("Got Datagram. data: %#v %#v %#v %#v %#v %#v datagram address: %#v\n", d.Rsv, d.Frag, d.Atyp, d.DstAddr, d.DstPort, d.Data, d.Address())
	}
	return d, nil
}

// NewDatagram return datagram packet can be writed into client, dstaddr should not have domain length
func NewDatagramC(atyp byte, dstaddr []byte, dstport []byte, data []byte) *DatagramC {
	if atyp == ATYPDomain {
		dstaddr = append([]byte{byte(len(dstaddr))}, dstaddr...)
	}
	return &DatagramC{
		Rsv:     []byte{0x00, 0x00},
		Frag:    0x00,
		Atyp:    atyp,
		DstAddr: dstaddr,
		DstPort: dstport,
		Data:    data,
	}
}

// Bytes return []byte
func (d *DatagramC) Bytes() []byte {
	b := make([]byte, 0)
	b = append(b, d.Rsv...)
	b = append(b, d.Frag)
	b = append(b, d.Atyp)
	b = append(b, d.DstAddr...)
	b = append(b, d.DstPort...)
	b = append(b, d.Data...)
	return b
}