socks5/util.go

package socks5

import (
	"encoding/binary"
	"io"
	"net"
	"strconv"
)

// NewEmptyAddrReply returns reply with empty address and port
func NewEmptyAddrReply(status ReplyStatus, atyp ATYP) *Reply {
	if atyp == ATYPIPv6 {
		return NewReply(status, ATYPIPv6, []byte(net.IPv6zero), []byte{0x00, 0x00})
	}

	return NewReply(status, ATYPIPv4, []byte{0x00, 0x00, 0x00, 0x00}, []byte{0x00, 0x00})
}

// ReadAddress reads address from reader
func ReadAddress(r io.Reader, atyp ATYP) ([]byte, error) {
	var addr []byte

	//nolint:exhaustive
	switch atyp {
	case ATYPIPv4:
		addr = make([]byte, 4)
		if _, err := io.ReadFull(r, addr); err != nil {
			return nil, err
		}
	case ATYPIPv6:
		addr = make([]byte, 16)
		if _, err := io.ReadFull(r, addr); err != nil {
			return nil, err
		}
	case ATYPFQDN:
		domainLen := make([]byte, 1)
		if _, err := io.ReadFull(r, domainLen); err != nil {
			return nil, err
		}

		if domainLen[0] == 0 {
			return nil, ErrBadRequest
		}

		addr = make([]byte, int(domainLen[0]))
		if _, err := io.ReadFull(r, addr); err != nil {
			return nil, err
		}

		addr = append(domainLen, addr...) //nolint:makezero
	default:
		return nil, ErrBadRequest
	}

	return addr, nil
}

// ParseAddress parses address from string
func ParseAddress(address string) (ATYP, []byte, []byte, error) {
	host, port, err := net.SplitHostPort(address)
	if err != nil {
		return 0x00, []byte{}, []byte{}, err
	}

	var (
		atyp ATYP
		addr []byte
	)

	ip := net.ParseIP(host)
	if ip4 := ip.To4(); ip4 != nil {
		atyp = ATYPIPv4
		addr = []byte(ip4)
	} else if ip6 := ip.To16(); ip6 != nil {
		atyp = ATYPIPv6
		addr = []byte(ip6)
	} else {
		atyp = ATYPFQDN
		addr = []byte{byte(len(host))}
		addr = append(addr, []byte(host)...)
	}

	portInt, err := strconv.Atoi(port)
	if err != nil {
		return 0x00, []byte{}, []byte{}, err
	}

	portBytes := make([]byte, 2)
	binary.BigEndian.PutUint16(portBytes, uint16(portInt))

	return atyp, addr, portBytes, nil
}