+ SOCKS 4/5 tests

= Basic build and dissection - test version dispatch

p1 = Ether(raw(Ether()/IP()/TCP()/SOCKS()/SOCKS5Request()))
p2 = Ether(raw(Ether()/IP()/TCP()/SOCKS()/SOCKS5Reply()))
p3 = Ether(raw(Ether()/IP()/TCP()/SOCKS()/SOCKS4Request()))
p4 = Ether(raw(Ether()/IP()/TCP()/SOCKS()/SOCKS4Reply()))

assert p1[TCP].dport == 1080
assert p1[SOCKS].vn == 0x5
assert SOCKS5Request in p1

assert p2[TCP].sport == 1080
assert p2[SOCKS].vn == 0x5
assert SOCKS5Reply in p2

assert p3[TCP].dport == 1080
assert p3[SOCKS].vn == 0x4
assert SOCKS4Request in p3

assert p4[TCP].sport == 1080
assert p4[SOCKS].vn == 0x0
assert SOCKS4Reply in p4

= SOCKS5Request build and dissection

pkt = IP(dst="127.0.0.1", src="127.0.0.1")/TCP(sport=123)/SOCKS()/SOCKS5Request(atyp=0x3, addr="scapy.net")
assert raw(pkt) == b'E\x00\x009\x00\x01\x00\x00@\x06|\xbc\x7f\x00\x00\x01\x7f\x00\x00\x01\x049\x048\x00\x00\x00\x00\x00\x00\x00\x00P\x02 \x00\xf2*\x00\x00\x05\x00\x00\x03\x05scapy\x03net\x00\x00P'
pkt = IP(raw(pkt))

assert SOCKS5Request in pkt
assert pkt[SOCKS5Request].addr == b'scapy.net.'

= Test SOCKSv5 over UDP

pkt = Ether()/IP()/UDP()/SOCKS5UDP(port=53)/DNS()
pkt = Ether(raw(pkt))
assert DNS in pkt