def tcp_timestamp_test():
p = Packet(tlspkt)
(bef_tsval, _, _) = p.parse_timestamp()
p.offset_timestamp(4, True)
(after_tsval, _, _) = p.parse_timestamp()
assert (bef_tsval + 4 == after_tsval)
# Verify the TCP checksum
before = p.get_tcp_cksum()
p.update_cksum()
after = p.get_tcp_cksum()
assert (abs(after - before) == 4)
def tcp_cksum_test():
p = Packet(tlspkt)
before = p.get_tcp_cksum()
p.update_cksum()
after = p.get_tcp_cksum()
assert (before == after)