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1# Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
2# Use of this source code is governed by a BSD-style license that can be
3# found in the LICENSE file.
4
5import logging
6import os
7import shutil
8
9from autotest_lib.client.common_lib import error, utils
10from autotest_lib.client.common_lib.cros import avahi_utils
11from autotest_lib.client.cros import service_stopper, tcpdump
12
13
14P2P_SHARE_PATH = '/var/cache/p2p'
15
16# A path used to store the existing p2p files during the test and restore them
17# once the test finishes.
18P2P_SHARE_BACKUP_PATH = '/var/cache/p2p-backup'
19
20
21def p2p_backup_files(backup_path=P2P_SHARE_BACKUP_PATH):
22    """Backup the P2P shared files and create an empty shared directory.
23
24    p2p-server shall not be running during backup or restore.
25
26    @param backup_path: The path where the files will be moved to.
27    @raise error.TestError
28    """
29    try:
30        if os.path.exists(backup_path):
31            shutil.rmtree(backup_path)
32        if os.path.exists(P2P_SHARE_PATH):
33            os.rename(P2P_SHARE_PATH, backup_path)
34    except OSError, e:
35        raise error.TestError("Error on P2P files backup: %s" % (e.message))
36
37
38def p2p_restore_files(backup_path=P2P_SHARE_BACKUP_PATH):
39    """Restore the P2P shared files from a backup and *delete* the backup.
40
41    p2p-server shall not be running during backup or restore.
42
43    @param backup_path: The path where the files will be moved from.
44    """
45    if os.path.exists(P2P_SHARE_PATH):
46        shutil.rmtree(P2P_SHARE_PATH, ignore_errors=True)
47    if os.path.exists(backup_path):
48        os.rename(backup_path, P2P_SHARE_PATH)
49
50
51class P2PServerOverTap(object):
52    """Manage a p2p-server instance running over a TAP interface.
53
54    This class manages a p2p-server instance configured to run over a TAP
55    interface, useful for any test that needs to interact with the p2p-server
56    (and its p2p-http-server instance) on a controled network environment.
57    """
58    def __init__(self, tap_ip='169.254.10.1', tap_mask=24, tap_name='faketap'):
59        """Initialize the configuration.
60
61        @param tap_ip: IPv4 address for the TAP interface on the DUT's end.
62        @param tap_mask: Network mask fot the tap_ip address.
63        @param tap_name: The name prefix for the TAP interface.
64        """
65        # The network 169.254/16 shouldn't clash with other real services and we
66        # use a /24 subnet of it as the default safe value here.
67        self._tap_ip = tap_ip
68        self._tap_mask = tap_mask
69        self._tap_name = tap_name
70        self._services = None
71        self.tap = None
72        self._tcpdump = None
73
74
75    def setup(self, dumpdir=None):
76        """Initializes avahi daemon on a new tap interface.
77
78        @param dumpdir: Directory where the traffic on the new tap interface
79                        is recorded. A value of None disables traffic dumping.
80        """
81        try:
82            from lansim import tuntap
83        except ImportError:
84            logging.exception('Failed to import lansim.')
85            raise error.TestError('Error importing lansim. Did you setup_dep '
86                                  'and install_pkg lansim on your test?')
87
88        # Ensure p2p and avahi aren't running.
89        self._services = service_stopper.ServiceStopper(['p2p', 'avahi'])
90        self._services.stop_services()
91
92        # Backup p2p files.
93        p2p_backup_files()
94
95        # Initialize the TAP interface.
96        self.tap = tuntap.TunTap(tuntap.IFF_TAP, name=self._tap_name)
97        self.tap.set_addr(self._tap_ip, self._tap_mask)
98        self.tap.up()
99
100        # Enable traffic dump.
101        if not dumpdir is None:
102            dumpfile = os.path.join(dumpdir, 'dump-%s.pcap' % self.tap.name)
103            self._tcpdump = tcpdump.Tcpdump(self.tap.name, dumpfile)
104
105        # Re-launch avahi-daemon on the TAP interface only.
106        avahi_utils.avahi_start_on_iface(self.tap.name)
107        utils.system("start p2p")
108
109
110    def cleanup(self):
111        """Restore the original environment as before the call to setup().
112
113        This method makes a best-effort attempt to restore the environment and
114        logs all the errors encountered but doesn't fail.
115        """
116        try:
117            utils.system('stop p2p')
118            avahi_utils.avahi_stop()
119        except:
120            logging.exception('Failed to stop tested services.')
121
122        if self._tcpdump:
123            self._tcpdump.stop()
124
125        if self.tap:
126            self.tap.down()
127
128        # Restore p2p files.
129        try:
130            p2p_restore_files()
131        except OSError:
132            logging.exception('Failed to restore the P2P backup.')
133
134        if self._services:
135            self._services.restore_services()
136