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#!/usr/bin/env python3
import unittest
from framework import VppTestCase, VppTestRunner
from scapy.layers.inet import IP, TCP
from scapy.layers.inet6 import IPv6
from scapy.layers.l2 import Ether
from scapy.packet import Raw
class TestMSSClamp(VppTestCase):
""" TCP MSS Clamping Test Case """
def setUp(self):
super(TestMSSClamp, self).setUp()
# create 2 pg interfaces
self.create_pg_interfaces(range(2))
for i in self.pg_interfaces:
i.admin_up()
i.config_ip4()
i.resolve_arp()
i.config_ip6()
i.resolve_ndp()
def tearDown(self):
for i in self.pg_interfaces:
i.unconfig_ip4()
i.unconfig_ip6()
i.admin_down()
super(TestMSSClamp, self).tearDown()
def verify_pkt(self, rx, expected_mss):
# check that the MSS size equals the expected value
# and the IP and TCP checksums are correct
tcp = rx[TCP]
tcp_csum = tcp.chksum
del tcp.chksum
ip_csum = 0
if (rx.haslayer(IP)):
ip_csum = rx[IP].chksum
del rx[IP].chksum
opt = tcp.options
self.assertEqual(opt[0][0], 'MSS')
self.assertEqual(opt[0][1], expected_mss)
# recalculate checksums
rx = rx.__class__(bytes(rx))
tcp = rx[TCP]
self.assertEqual(tcp_csum, tcp.chksum)
if (rx.haslayer(IP)):
self.assertEqual(ip_csum, rx[IP].chksum)
def send_and_verify_ip4(self, src_pg, dst_pg, mss, expected_mss):
# IPv4 TCP packet with the requested MSS option.
# from a host on src_pg to a host on dst_pg.
p = (Ether(dst=src_pg.local_mac,
src=src_pg.remote_mac) /
IP(src=src_pg.remote_ip4,
dst=dst_pg.remote_ip4) /
TCP(sport=1234, dport=1234,
flags="S",
options=[('MSS', (mss)), ('EOL', None)]) /
Raw('\xa5' * 100))
rxs = self.send_and_expect(src_pg, p * 65, dst_pg)
for rx in rxs:
self.verify_pkt(rx, expected_mss)
def send_and_verify_ip6(self, src_pg, dst_pg, mss, expected_mss):
#
# IPv6 TCP packet with the requested MSS option.
# from a host on src_pg to a host on dst_pg.
#
p = (Ether(dst=src_pg.local_mac,
src=src_pg.remote_mac) /
IPv6(src=src_pg.remote_ip6,
dst=dst_pg.remote_ip6) /
TCP(sport=1234, dport=1234,
flags="S",
options=[('MSS', (mss)), ('EOL', None)]) /
Raw('\xa5' * 100))
rxs = self.send_and_expect(src_pg, p * 65, dst_pg)
for rx in rxs:
self.verify_pkt(rx, expected_mss)
def test_tcp_mss_clamping_ip4_tx(self):
""" IP4 TCP MSS Clamping TX """
# enable the TCP MSS clamping feature to lower the MSS to 1424.
self.vapi.mss_clamp_enable_disable(self.pg1.sw_if_index,
ipv4_mss=1424, ipv6_mss=0,
ipv4_direction=3, ipv6_direction=0)
# Verify that the feature is enabled.
rv, reply = self.vapi.mss_clamp_get(sw_if_index=self.pg1.sw_if_index)
self.assertEqual(reply[0].ipv4_mss, 1424)
self.assertEqual(reply[0].ipv4_direction, 3)
# Send syn packets and verify that the MSS value is lowered.
self.send_and_verify_ip4(self.pg0, self.pg1, 1460, 1424)
# check the stats
stats = self.statistics.get_counter(
'/err/tcp-mss-clamping-ip4-out/clamped')
self.assertEqual(sum(stats), 65)
# Send syn packets with small enough MSS values and verify they are
# unchanged.
self.send_and_verify_ip4(self.pg0, self.pg1, 1400, 1400)
# enable the the feature only in TX direction
# and change the max MSS value
self.vapi.mss_clamp_enable_disable(self.pg1.sw_if_index,
ipv4_mss=1420, ipv6_mss=0,
ipv4_direction=2, ipv6_direction=0)
# Send syn packets and verify that the MSS value is lowered.
self.send_and_verify_ip4(self.pg0, self.pg1, 1460, 1420)
# enable the the feature only in RX direction
self.vapi.mss_clamp_enable_disable(self.pg1.sw_if_index,
ipv4_mss=1424, ipv6_mss=0,
ipv4_direction=1, ipv6_direction=0)
# Send the packets again and ensure they are unchanged.
self.send_and_verify_ip4(self.pg0, self.pg1, 1460, 1460)
# disable the feature
self.vapi.mss_clamp_enable_disable(self.pg1.sw_if_index,
ipv4_mss=0, ipv6_mss=0,
ipv4_direction=0, ipv6_direction=0)
# Send the packets again and ensure they are unchanged.
self.send_and_verify_ip4(self.pg0, self.pg1, 1460, 1460)
def test_tcp_mss_clamping_ip4_rx(self):
""" IP4 TCP MSS Clamping RX """
# enable the TCP MSS clamping feature to lower the MSS to 1424.
self.vapi.mss_clamp_enable_disable(self.pg1.sw_if_index,
ipv4_mss=1424, ipv6_mss=0,
ipv4_direction=3, ipv6_direction=0)
# Verify that the feature is enabled.
rv, reply = self.vapi.mss_clamp_get(sw_if_index=self.pg1.sw_if_index)
self.assertEqual(reply[0].ipv4_mss, 1424)
self.assertEqual(reply[0].ipv4_direction, 3)
# Send syn packets and verify that the MSS value is lowered.
self.send_and_verify_ip4(self.pg1, self.pg0, 1460, 1424)
# check the stats
stats = self.statistics.get_counter(
'/err/tcp-mss-clamping-ip4-in/clamped')
self.assertEqual(sum(stats), 65)
# Send syn packets with small enough MSS values and verify they are
# unchanged.
self.send_and_verify_ip4(self.pg1, self.pg0, 1400, 1400)
# enable the the feature only in RX direction
# and change the max MSS value
self.vapi.mss_clamp_enable_disable(self.pg1.sw_if_index,
ipv4_mss=1420, ipv6_mss=0,
ipv4_direction=1, ipv6_direction=0)
# Send syn packets and verify that the MSS value is lowered.
self.send_and_verify_ip4(self.pg1, self.pg0, 1460, 1420)
# enable the the feature only in TX direction
self.vapi.mss_clamp_enable_disable(self.pg1.sw_if_index,
ipv4_mss=1424, ipv6_mss=0,
ipv4_direction=2, ipv6_direction=0)
# Send the packets again and ensure they are unchanged.
self.send_and_verify_ip4(self.pg1, self.pg0, 1460, 1460)
# disable the feature
self.vapi.mss_clamp_enable_disable(self.pg1.sw_if_index,
ipv4_mss=0, ipv6_mss=0,
ipv4_direction=0, ipv6_direction=0)
# Send the packets again and ensure they are unchanged.
self.send_and_verify_ip4(self.pg1, self.pg0, 1460, 1460)
def test_tcp_mss_clamping_ip6_tx(self):
""" IP6 TCP MSS Clamping TX """
# enable the TCP MSS clamping feature to lower the MSS to 1424.
self.vapi.mss_clamp_enable_disable(self.pg1.sw_if_index,
ipv4_mss=0, ipv6_mss=1424,
ipv4_direction=0, ipv6_direction=3)
# Verify that the feature is enabled.
rv, reply = self.vapi.mss_clamp_get(sw_if_index=self.pg1.sw_if_index)
self.assertEqual(reply[0].ipv6_mss, 1424)
self.assertEqual(reply[0].ipv6_direction, 3)
# Send syn packets and verify that the MSS value is lowered.
self.send_and_verify_ip6(self.pg0, self.pg1, 1460, 1424)
# check the stats
stats = self.statistics.get_counter(
'/err/tcp-mss-clamping-ip6-out/clamped')
self.assertEqual(sum(stats), 65)
# Send syn packets with small enough MSS values and verify they are
# unchanged.
self.send_and_verify_ip6(self.pg0, self.pg1, 1400, 1400)
# enable the the feature only in TX direction
# and change the max MSS value
self.vapi.mss_clamp_enable_disable(self.pg1.sw_if_index,
ipv4_mss=0, ipv6_mss=1420,
ipv4_direction=0, ipv6_direction=2)
# Send syn packets and verify that the MSS value is lowered.
self.send_and_verify_ip6(self.pg0, self.pg1, 1460, 1420)
# enable the the feature only in RX direction
self.vapi.mss_clamp_enable_disable(self.pg1.sw_if_index,
ipv4_mss=0, ipv6_mss=1424,
ipv4_direction=0, ipv6_direction=1)
# Send the packets again and ensure they are unchanged.
self.send_and_verify_ip6(self.pg0, self.pg1, 1460, 1460)
# disable the feature
self.vapi.mss_clamp_enable_disable(self.pg1.sw_if_index,
ipv4_mss=0, ipv6_mss=0,
ipv4_direction=0, ipv6_direction=0)
# Send the packets again and ensure they are unchanged.
self.send_and_verify_ip6(self.pg0, self.pg1, 1460, 1460)
def test_tcp_mss_clamping_ip6_rx(self):
""" IP6 TCP MSS Clamping RX """
# enable the TCP MSS clamping feature to lower the MSS to 1424.
self.vapi.mss_clamp_enable_disable(self.pg1.sw_if_index,
ipv4_mss=0, ipv6_mss=1424,
ipv4_direction=0, ipv6_direction=3)
# Verify that the feature is enabled.
rv, reply = self.vapi.mss_clamp_get(sw_if_index=self.pg1.sw_if_index)
self.assertEqual(reply[0].ipv6_mss, 1424)
self.assertEqual(reply[0].ipv6_direction, 3)
# Send syn packets and verify that the MSS value is lowered.
self.send_and_verify_ip6(self.pg1, self.pg0, 1460, 1424)
# check the stats
stats = self.statistics.get_counter(
'/err/tcp-mss-clamping-ip6-in/clamped')
self.assertEqual(sum(stats), 65)
# Send syn packets with small enough MSS values and verify they are
# unchanged.
self.send_and_verify_ip6(self.pg1, self.pg0, 1400, 1400)
# enable the the feature only in RX direction
# and change the max MSS value
self.vapi.mss_clamp_enable_disable(self.pg1.sw_if_index,
ipv4_mss=0, ipv6_mss=1420,
ipv4_direction=0, ipv6_direction=1)
# Send syn packets and verify that the MSS value is lowered.
self.send_and_verify_ip6(self.pg1, self.pg0, 1460, 1420)
# enable the the feature only in TX direction
self.vapi.mss_clamp_enable_disable(self.pg1.sw_if_index,
ipv4_mss=0, ipv6_mss=1424,
ipv4_direction=0, ipv6_direction=2)
# Send the packets again and ensure they are unchanged.
self.send_and_verify_ip6(self.pg1, self.pg0, 1460, 1460)
# disable the feature
self.vapi.mss_clamp_enable_disable(self.pg1.sw_if_index,
ipv4_mss=0, ipv6_mss=0,
ipv4_direction=0, ipv6_direction=0)
# Send the packets again and ensure they are unchanged.
self.send_and_verify_ip6(self.pg1, self.pg0, 1460, 1460)
if __name__ == '__main__':
unittest.main(testRunner=VppTestRunner)
|
