net: add rfc3442 (classless static routes) to EphemeralDHCP

The EphemeralDHCP context manager did not parse or handle
rfc3442 classless static routes which prevented reading
datasource metadata in some clouds.  This branch adds support
for extracting the field from the leases output, parsing the
format and then adding the required iproute2 ip commands to
apply (and teardown) the static routes.

LP: #1821102

2 files changed, 158 insertions, 1 deletions

diff --git a/cloudinit/net/tests/test_dhcp.py b/cloudinit/net/tests/test_dhcp.py
index 51390249..91f503c9 100644
--- a/cloudinit/net/tests/test_dhcp.py
+++ b/cloudinit/net/tests/test_dhcp.py
@@ -8,7 +8,8 @@ from textwrap import dedent
 import cloudinit.net as net
 from cloudinit.net.dhcp import (
     InvalidDHCPLeaseFileError, maybe_perform_dhcp_discovery,
-    parse_dhcp_lease_file, dhcp_discovery, networkd_load_leases)
+    parse_dhcp_lease_file, dhcp_discovery, networkd_load_leases,
+    parse_static_routes)
 from cloudinit.util import ensure_file, write_file
 from cloudinit.tests.helpers import (
     CiTestCase, HttprettyTestCase, mock, populate_dir, wrap_and_call)
@@ -64,6 +65,123 @@ class TestParseDHCPLeasesFile(CiTestCase):
         self.assertItemsEqual(expected, parse_dhcp_lease_file(lease_file))
 
 
+class TestDHCPRFC3442(CiTestCase):
+
+    def test_parse_lease_finds_rfc3442_classless_static_routes(self):
+        """parse_dhcp_lease_file returns rfc3442-classless-static-routes."""
+        lease_file = self.tmp_path('leases')
+        content = dedent("""
+            lease {
+              interface "wlp3s0";
+              fixed-address 192.168.2.74;
+              option subnet-mask 255.255.255.0;
+              option routers 192.168.2.1;
+              option rfc3442-classless-static-routes 0,130,56,240,1;
+              renew 4 2017/07/27 18:02:30;
+              expire 5 2017/07/28 07:08:15;
+            }
+        """)
+        expected = [
+            {'interface': 'wlp3s0', 'fixed-address': '192.168.2.74',
+             'subnet-mask': '255.255.255.0', 'routers': '192.168.2.1',
+             'rfc3442-classless-static-routes': '0,130,56,240,1',
+             'renew': '4 2017/07/27 18:02:30',
+             'expire': '5 2017/07/28 07:08:15'}]
+        write_file(lease_file, content)
+        self.assertItemsEqual(expected, parse_dhcp_lease_file(lease_file))
+
+    @mock.patch('cloudinit.net.dhcp.EphemeralIPv4Network')
+    @mock.patch('cloudinit.net.dhcp.maybe_perform_dhcp_discovery')
+    def test_obtain_lease_parses_static_routes(self, m_maybe, m_ipv4):
+        """EphemeralDHPCv4 parses rfc3442 routes for EphemeralIPv4Network"""
+        lease = [
+            {'interface': 'wlp3s0', 'fixed-address': '192.168.2.74',
+             'subnet-mask': '255.255.255.0', 'routers': '192.168.2.1',
+             'rfc3442-classless-static-routes': '0,130,56,240,1',
+             'renew': '4 2017/07/27 18:02:30',
+             'expire': '5 2017/07/28 07:08:15'}]
+        m_maybe.return_value = lease
+        eph = net.dhcp.EphemeralDHCPv4()
+        eph.obtain_lease()
+        expected_kwargs = {
+            'interface': 'wlp3s0',
+            'ip': '192.168.2.74',
+            'prefix_or_mask': '255.255.255.0',
+            'broadcast': '192.168.2.255',
+            'static_routes': [('0.0.0.0/0', '130.56.240.1')],
+            'router': '192.168.2.1'}
+        m_ipv4.assert_called_with(**expected_kwargs)
+
+
+class TestDHCPParseStaticRoutes(CiTestCase):
+
+    with_logs = True
+
+    def parse_static_routes_empty_string(self):
+        self.assertEqual([], parse_static_routes(""))
+
+    def test_parse_static_routes_invalid_input_returns_empty_list(self):
+        rfc3442 = "32,169,254,169,254,130,56,248"
+        self.assertEqual([], parse_static_routes(rfc3442))
+
+    def test_parse_static_routes_bogus_width_returns_empty_list(self):
+        rfc3442 = "33,169,254,169,254,130,56,248"
+        self.assertEqual([], parse_static_routes(rfc3442))
+
+    def test_parse_static_routes_single_ip(self):
+        rfc3442 = "32,169,254,169,254,130,56,248,255"
+        self.assertEqual([('169.254.169.254/32', '130.56.248.255')],
+                         parse_static_routes(rfc3442))
+
+    def test_parse_static_routes_single_ip_handles_trailing_semicolon(self):
+        rfc3442 = "32,169,254,169,254,130,56,248,255;"
+        self.assertEqual([('169.254.169.254/32', '130.56.248.255')],
+                         parse_static_routes(rfc3442))
+
+    def test_parse_static_routes_default_route(self):
+        rfc3442 = "0,130,56,240,1"
+        self.assertEqual([('0.0.0.0/0', '130.56.240.1')],
+                         parse_static_routes(rfc3442))
+
+    def test_parse_static_routes_class_c_b_a(self):
+        class_c = "24,192,168,74,192,168,0,4"
+        class_b = "16,172,16,172,16,0,4"
+        class_a = "8,10,10,0,0,4"
+        rfc3442 = ",".join([class_c, class_b, class_a])
+        self.assertEqual(sorted([
+            ("192.168.74.0/24", "192.168.0.4"),
+            ("172.16.0.0/16", "172.16.0.4"),
+            ("10.0.0.0/8", "10.0.0.4")
+        ]), sorted(parse_static_routes(rfc3442)))
+
+    def test_parse_static_routes_logs_error_truncated(self):
+        bad_rfc3442 = {
+            "class_c": "24,169,254,169,10",
+            "class_b": "16,172,16,10",
+            "class_a": "8,10,10",
+            "gateway": "0,0",
+            "netlen":  "33,0",
+        }
+        for rfc3442 in bad_rfc3442.values():
+            self.assertEqual([], parse_static_routes(rfc3442))
+
+        logs = self.logs.getvalue()
+        self.assertEqual(len(bad_rfc3442.keys()), len(logs.splitlines()))
+
+    def test_parse_static_routes_returns_valid_routes_until_parse_err(self):
+        class_c = "24,192,168,74,192,168,0,4"
+        class_b = "16,172,16,172,16,0,4"
+        class_a_error = "8,10,10,0,0"
+        rfc3442 = ",".join([class_c, class_b, class_a_error])
+        self.assertEqual(sorted([
+            ("192.168.74.0/24", "192.168.0.4"),
+            ("172.16.0.0/16", "172.16.0.4"),
+        ]), sorted(parse_static_routes(rfc3442)))
+
+        logs = self.logs.getvalue()
+        self.assertIn(rfc3442, logs.splitlines()[0])
+
+
 class TestDHCPDiscoveryClean(CiTestCase):
     with_logs = True
 
diff --git a/cloudinit/net/tests/test_init.py b/cloudinit/net/tests/test_init.py
index 6d2affe7..d393e6ad 100644
--- a/cloudinit/net/tests/test_init.py
+++ b/cloudinit/net/tests/test_init.py
@@ -549,6 +549,45 @@ class TestEphemeralIPV4Network(CiTestCase):
             self.assertEqual(expected_setup_calls, m_subp.call_args_list)
         m_subp.assert_has_calls(expected_teardown_calls)
 
+    def test_ephemeral_ipv4_network_with_rfc3442_static_routes(self, m_subp):
+        params = {
+            'interface': 'eth0', 'ip': '192.168.2.2',
+            'prefix_or_mask': '255.255.255.0', 'broadcast': '192.168.2.255',
+            'static_routes': [('169.254.169.254/32', '192.168.2.1'),
+                              ('0.0.0.0/0', '192.168.2.1')],
+            'router': '192.168.2.1'}
+        expected_setup_calls = [
+            mock.call(
+                ['ip', '-family', 'inet', 'addr', 'add', '192.168.2.2/24',
+                 'broadcast', '192.168.2.255', 'dev', 'eth0'],
+                capture=True, update_env={'LANG': 'C'}),
+            mock.call(
+                ['ip', '-family', 'inet', 'link', 'set', 'dev', 'eth0', 'up'],
+                capture=True),
+            mock.call(
+                ['ip', '-4', 'route', 'add', '169.254.169.254/32',
+                 'via', '192.168.2.1', 'dev', 'eth0'], capture=True),
+            mock.call(
+                ['ip', '-4', 'route', 'add', '0.0.0.0/0',
+                 'via', '192.168.2.1', 'dev', 'eth0'], capture=True)]
+        expected_teardown_calls = [
+            mock.call(
+                ['ip', '-4', 'route', 'del', '0.0.0.0/0',
+                 'via', '192.168.2.1', 'dev', 'eth0'], capture=True),
+            mock.call(
+                ['ip', '-4', 'route', 'del', '169.254.169.254/32',
+                 'via', '192.168.2.1', 'dev', 'eth0'], capture=True),
+            mock.call(
+                ['ip', '-family', 'inet', 'link', 'set', 'dev',
+                 'eth0', 'down'], capture=True),
+            mock.call(
+                ['ip', '-family', 'inet', 'addr', 'del',
+                 '192.168.2.2/24', 'dev', 'eth0'], capture=True)
+        ]
+        with net.EphemeralIPv4Network(**params):
+            self.assertEqual(expected_setup_calls, m_subp.call_args_list)
+        m_subp.assert_has_calls(expected_setup_calls + expected_teardown_calls)
+
 
 class TestApplyNetworkCfgNames(CiTestCase):
     V1_CONFIG = textwrap.dedent("""\