socks4/4a client does not work

[dyhkwong]

PR #1269 claims to have added socks4/4a client support. However, no matter what socks version specified, it is actually always a socks5 client because it handshakes with ClientHandshake, which is for socks5 only. We need a different handshake function for socks4(a).

v2ray-core/proxy/socks/client.go

Line 149 in 2e0ea88

udpRequest, err := ClientHandshake(request, conn, conn)

v2ray-core/proxy/socks/protocol.go

Lines 450 to 459 in 2e0ea88

	func ClientHandshake(request *protocol.RequestHeader, reader io.Reader, writer io.Writer) (*protocol.RequestHeader, error) {
	authByte := byte(authNotRequired)
	if request.User != nil {
	authByte = byte(authPassword)
	}
	b := buf.New()
	defer b.Release()
	common.Must2(b.Write([]byte{socks5Version, 0x01, authByte}))