0xFA: pLl | pp, // 'ú'
	0xFB: pLl | pp, // 'û'
	0xFC: pLl | pp, // 'ü'
	0xFD: pLl | pp, // 'ý'
	0xFE: pLl | pp, // 'þ'
	0xFF: pLl | pp, // 'ÿ'
}

var asciiFold = [MaxASCII + 1]uint16{
	0x0000,
	0x0001,
	0x0002,
	0x0003,
	0x0004,
	0x0005,
	0x0006,
	0x0007,
	0x0008,
	0x0009,
	0x000A,
	0x000B,
	0x000C,
	0x000D,
	0x000E,
	0x000F,

			return
		}
		if _, err := io.ReadFull(s, buf[4:ipLen+6]); err != nil {
			t.Errorf("socks5 proxy address read: %v", err)
			return
		}
		ip := net.IP(buf[4 : ipLen+4])
		port := binary.BigEndian.Uint16(buf[ipLen+4 : ipLen+6])
		copy(buf[:3], []byte{5, 0, 0})
		if _, err := s.Write(buf[:ipLen+6]); err != nil {
			t.Errorf("socks5 proxy connect write: %v", err)
			return
		}

	c3 := &xcmp[a3]
	c4 := &xcmp[a4]
	c5 := &xcmp[a5]
	for i := range ops {
		op := &ops[i]
		if c1[op.a1] && c2[op.a2] && c3[op.a3] && c4[op.a4] && c5[op.a5] && p.Scond == op.scond {
			p.Optab = uint16(cap(optab) - cap(ops) + i + 1)
			return op
		}
	}

	c.ctxt.Diag("illegal combination: %v %v %v %v %v %v, %d %d", p, DRconv(a1), DRconv(a2), DRconv(a3), DRconv(a4), DRconv(a5), p.From.Type, p.To.Type)