1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
|
# Copyright (C) 2017 Canonical Ltd.
#
# Author: Chad Smith <chad.smith@canonical.com>
#
# This file is part of cloud-init. See LICENSE file for license information.
import configobj
import logging
import os
import re
import signal
from cloudinit.net import find_fallback_nic, get_devicelist
from cloudinit import temp_utils
from cloudinit import util
from six import StringIO
LOG = logging.getLogger(__name__)
NETWORKD_LEASES_DIR = '/run/systemd/netif/leases'
class InvalidDHCPLeaseFileError(Exception):
"""Raised when parsing an empty or invalid dhcp.leases file.
Current uses are DataSourceAzure and DataSourceEc2 during ephemeral
boot to scrape metadata.
"""
pass
def maybe_perform_dhcp_discovery(nic=None):
"""Perform dhcp discovery if nic valid and dhclient command exists.
If the nic is invalid or undiscoverable or dhclient command is not found,
skip dhcp_discovery and return an empty dict.
@param nic: Name of the network interface we want to run dhclient on.
@return: A dict of dhcp options from the dhclient discovery if run,
otherwise an empty dict is returned.
"""
if nic is None:
nic = find_fallback_nic()
if nic is None:
LOG.debug(
'Skip dhcp_discovery: Unable to find fallback nic.')
return {}
elif nic not in get_devicelist():
LOG.debug(
'Skip dhcp_discovery: nic %s not found in get_devicelist.', nic)
return {}
dhclient_path = util.which('dhclient')
if not dhclient_path:
LOG.debug('Skip dhclient configuration: No dhclient command found.')
return {}
with temp_utils.tempdir(prefix='cloud-init-dhcp-', needs_exe=True) as tdir:
# Use /var/tmp because /run/cloud-init/tmp is mounted noexec
return dhcp_discovery(dhclient_path, nic, tdir)
def parse_dhcp_lease_file(lease_file):
"""Parse the given dhcp lease file for the most recent lease.
Return a dict of dhcp options as key value pairs for the most recent lease
block.
@raises: InvalidDHCPLeaseFileError on empty of unparseable leasefile
content.
"""
lease_regex = re.compile(r"lease {(?P<lease>[^}]*)}\n")
dhcp_leases = []
lease_content = util.load_file(lease_file)
if len(lease_content) == 0:
raise InvalidDHCPLeaseFileError(
'Cannot parse empty dhcp lease file {0}'.format(lease_file))
for lease in lease_regex.findall(lease_content):
lease_options = []
for line in lease.split(';'):
# Strip newlines, double-quotes and option prefix
line = line.strip().replace('"', '').replace('option ', '')
if not line:
continue
lease_options.append(line.split(' ', 1))
dhcp_leases.append(dict(lease_options))
if not dhcp_leases:
raise InvalidDHCPLeaseFileError(
'Cannot parse dhcp lease file {0}. No leases found'.format(
lease_file))
return dhcp_leases
def dhcp_discovery(dhclient_cmd_path, interface, cleandir):
"""Run dhclient on the interface without scripts or filesystem artifacts.
@param dhclient_cmd_path: Full path to the dhclient used.
@param interface: Name of the network inteface on which to dhclient.
@param cleandir: The directory from which to run dhclient as well as store
dhcp leases.
@return: A dict of dhcp options parsed from the dhcp.leases file or empty
dict.
"""
LOG.debug('Performing a dhcp discovery on %s', interface)
# XXX We copy dhclient out of /sbin/dhclient to avoid dealing with strict
# app armor profiles which disallow running dhclient -sf <our-script-file>.
# We want to avoid running /sbin/dhclient-script because of side-effects in
# /etc/resolv.conf any any other vendor specific scripts in
# /etc/dhcp/dhclient*hooks.d.
sandbox_dhclient_cmd = os.path.join(cleandir, 'dhclient')
util.copy(dhclient_cmd_path, sandbox_dhclient_cmd)
pid_file = os.path.join(cleandir, 'dhclient.pid')
lease_file = os.path.join(cleandir, 'dhcp.leases')
# ISC dhclient needs the interface up to send initial discovery packets.
# Generally dhclient relies on dhclient-script PREINIT action to bring the
# link up before attempting discovery. Since we are using -sf /bin/true,
# we need to do that "link up" ourselves first.
util.subp(['ip', 'link', 'set', 'dev', interface, 'up'], capture=True)
cmd = [sandbox_dhclient_cmd, '-1', '-v', '-lf', lease_file,
'-pf', pid_file, interface, '-sf', '/bin/true']
util.subp(cmd, capture=True)
pid = None
try:
pid = int(util.load_file(pid_file).strip())
return parse_dhcp_lease_file(lease_file)
finally:
if pid:
os.kill(pid, signal.SIGKILL)
def networkd_parse_lease(content):
"""Parse a systemd lease file content as in /run/systemd/netif/leases/
Parse this (almost) ini style file even though it says:
# This is private data. Do not parse.
Simply return a dictionary of key/values."""
return dict(configobj.ConfigObj(StringIO(content), list_values=False))
def networkd_load_leases(leases_d=None):
"""Return a dictionary of dictionaries representing each lease
found in lease_d.i
The top level key will be the filename, which is typically the ifindex."""
if leases_d is None:
leases_d = NETWORKD_LEASES_DIR
ret = {}
if not os.path.isdir(leases_d):
return ret
for lfile in os.listdir(leases_d):
ret[lfile] = networkd_parse_lease(
util.load_file(os.path.join(leases_d, lfile)))
return ret
def networkd_get_option_from_leases(keyname, leases_d=None):
if leases_d is None:
leases_d = NETWORKD_LEASES_DIR
leases = networkd_load_leases(leases_d=leases_d)
for ifindex, data in sorted(leases.items()):
if data.get(keyname):
return data[keyname]
return None
# vi: ts=4 expandtab
|
