/usr/lib/python2.7/dist-packages/provisioningserver/omshell.py is in python-maas-provisioningserver 1.5.4+bzr2294-0ubuntu1.2.
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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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 | # Copyright 2012 Canonical Ltd. This software is licensed under the
# GNU Affero General Public License version 3 (see the file LICENSE).
"""Python wrapper around the `omshell` utility which amends objects
inside the DHCP server.
"""
from __future__ import (
absolute_import,
print_function,
unicode_literals,
)
str = None
__metaclass__ = type
__all__ = [
"generate_omapi_key",
"Omshell",
]
import os
import re
from subprocess import (
PIPE,
Popen,
)
from textwrap import dedent
from provisioningserver.utils import (
call_capture_and_check,
ExternalProcessError,
parse_key_value_file,
tempdir,
)
bad_key_pattern = re.compile("[+/]no|no[+/]", flags=re.IGNORECASE)
def call_dnssec_keygen(tmpdir):
path = os.environ.get("PATH", "").split(os.pathsep)
path.append("/usr/sbin")
env = dict(os.environ, PATH=os.pathsep.join(path))
return call_capture_and_check(
['dnssec-keygen', '-r', '/dev/urandom', '-a', 'HMAC-MD5',
'-b', '512', '-n', 'HOST', '-K', tmpdir, '-q', 'omapi_key'],
env=env)
def run_repeated_keygen(tmpdir):
# omshell has a bug where if the chars '/' or '+' appear either
# side of the word 'no' (in any case), it throws an error like
# "partial base64 value left over". We check for that here and
# repeatedly generate a new key until a good one is generated.
key = None
while key is None:
key_id = call_dnssec_keygen(tmpdir)
# Locate the file that was written and strip out the Key: field in
# it.
if not key_id:
raise AssertionError("dnssec-keygen didn't generate anything")
key_id = key_id.strip() # Remove trailing newline.
key_file_name = os.path.join(tmpdir, key_id + '.private')
parsing_error = False
try:
config = parse_key_value_file(key_file_name)
except ValueError:
parsing_error = True
if parsing_error or 'Key' not in config:
raise AssertionError(
"Key field not found in output from dnssec-keygen")
key = config['Key']
if bad_key_pattern.search(key) is not None:
# Force a retry.
os.remove(key_file_name) # Stop dnssec_keygen complaints.
key = None
return key
def generate_omapi_key():
"""Generate a HMAC-MD5 key by calling out to the dnssec-keygen tool.
:return: The shared key suitable for OMAPI access.
:type: string
"""
# dnssec-keygen writes out files to a specified directory, so we
# need to make a temp directory for that.
# This relies on the temporary directory being accessible only to its
# owner.
temp_prefix = "%s." % os.path.basename(__file__)
with tempdir(prefix=temp_prefix) as tmpdir:
key = run_repeated_keygen(tmpdir)
return key
class Omshell:
"""Wrap up the omshell utility in Python.
'omshell' is an external executable that communicates with a DHCP daemon
and manipulates its objects. This class wraps up the commands necessary
to add and remove host maps (MAC to IP).
:param server_address: The address for the DHCP server (ip or hostname)
:param shared_key: An HMAC-MD5 key generated by dnssec-keygen like:
$ dnssec-keygen -r /dev/urandom -a HMAC-MD5 -b 512 -n HOST omapi_key
$ cat Komapi_key.+*.private |grep ^Key|cut -d ' ' -f2-
It must match the key set in the DHCP server's config which looks
like this:
omapi-port 7911;
key omapi_key {
algorithm HMAC-MD5;
secret "XXXXXXXXX"; #<-The output from the generated key above.
};
omapi-key omapi_key;
"""
def __init__(self, server_address, shared_key):
self.server_address = server_address
self.shared_key = shared_key
self.command = ["omshell"]
def _run(self, stdin):
proc = Popen(self.command, stdin=PIPE, stdout=PIPE)
stdout, stderr = proc.communicate(stdin)
if proc.poll() != 0:
raise ExternalProcessError(proc.returncode, self.command, stdout)
return proc.returncode, stdout
def create(self, ip_address, mac_address):
# The "name" is not a host name; it's an identifier used within
# the DHCP server. We just happen to use the IP address.
stdin = dedent("""\
server {self.server_address}
key omapi_key {self.shared_key}
connect
new host
set ip-address = {ip_address}
set hardware-address = {mac_address}
set hardware-type = 1
set name = "{ip_address}"
create
""")
stdin = stdin.format(
self=self, ip_address=ip_address, mac_address=mac_address)
returncode, output = self._run(stdin)
# If the call to omshell doesn't result in output containing the
# magic string 'hardware-type' then we can be reasonably sure
# that the 'create' command failed. Unfortunately there's no
# other output like "successful" to check so this is the best we
# can do.
if "hardware-type" in output:
# Success.
pass
elif "can't open object: I/O error" in output:
# Host map already existed. Treat as success.
pass
else:
raise ExternalProcessError(returncode, self.command, output)
def remove(self, ip_address):
# The "name" is not a host name; it's an identifier used within
# the DHCP server. We just happen to use the IP address.
stdin = dedent("""\
server {self.server_address}
key omapi_key {self.shared_key}
connect
new host
set name = "{ip_address}"
open
remove
""")
stdin = stdin.format(
self=self, ip_address=ip_address)
returncode, output = self._run(stdin)
# If the omshell worked, the last line should reference a null
# object.
lines = output.strip().splitlines()
try:
last_line = lines[-1]
except IndexError:
last_line = ""
if last_line != "obj: <null>":
raise ExternalProcessError(returncode, self.command, output)
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