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 list of dicts of representing the dhcp leases parsed from the
dhcp.leases file or empty list.
"""
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)
# Wait for pid file and lease file to appear, and for the process
# named by the pid file to daemonize (have pid 1 as its parent). If we
# try to read the lease file before daemonization happens, we might try
# to read it before the dhclient has actually written it. We also have
# to wait until the dhclient has become a daemon so we can be sure to
# kill the correct process, thus freeing cleandir to be deleted back
# up the callstack.
missing = util.wait_for_files(
[pid_file, lease_file], maxwait=5, naplen=0.01)
if missing:
LOG.warning("dhclient did not produce expected files: %s",
', '.join(os.path.basename(f) for f in missing))
return []
ppid = 'unknown'
for _ in range(0, 1000):
pid_content = util.load_file(pid_file).strip()
try:
pid = int(pid_content)
except ValueError:
pass
else:
ppid = util.get_proc_ppid(pid)
if ppid == 1:
LOG.debug('killing dhclient with pid=%s', pid)
os.kill(pid, signal.SIGKILL)
return parse_dhcp_lease_file(lease_file)
time.sleep(0.01)
LOG.error(
'dhclient(pid=%s, parentpid=%s) failed to daemonize after %s seconds',
pid_content, ppid, 0.01 * 1000
)
return parse_dhcp_lease_file(lease_file)
def test_get_proc_ppid(self):
"""get_proc_ppid returns correct parent pid value."""
my_pid = os.getpid()
my_ppid = os.getppid()
self.assertEqual(my_ppid, util.get_proc_ppid(my_pid))
def test_get_proc_ppid(self):
"""get_proc_ppid returns correct parent pid value."""
my_pid = os.getpid()
my_ppid = os.getppid()
self.assertEqual(my_ppid, util.get_proc_ppid(my_pid))
def dhcp_discovery(dhclient_cmd_path, interface, cleandir, dhcp_log_func=None):
"""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.
@param dhcp_log_func: A callable accepting the dhclient output and error
streams.
@return: A list of dicts of representing the dhcp leases parsed from the
dhcp.leases file or empty list.
"""
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")
# In some cases files in /var/tmp may not be executable, launching dhclient
# from there will certainly raise 'Permission denied' error. Try launching
# the original dhclient instead.
if not os.access(sandbox_dhclient_cmd, os.X_OK):
sandbox_dhclient_cmd = dhclient_cmd_path
# 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.
subp.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",
]
out, err = subp.subp(cmd, capture=True)
# Wait for pid file and lease file to appear, and for the process
# named by the pid file to daemonize (have pid 1 as its parent). If we
# try to read the lease file before daemonization happens, we might try
# to read it before the dhclient has actually written it. We also have
# to wait until the dhclient has become a daemon so we can be sure to
# kill the correct process, thus freeing cleandir to be deleted back
# up the callstack.
missing = util.wait_for_files([pid_file, lease_file],
maxwait=5,
naplen=0.01)
if missing:
LOG.warning(
"dhclient did not produce expected files: %s",
", ".join(os.path.basename(f) for f in missing),
)
return []
ppid = "unknown"
daemonized = False
for _ in range(0, 1000):
pid_content = util.load_file(pid_file).strip()
try:
pid = int(pid_content)
except ValueError:
pass
else:
ppid = util.get_proc_ppid(pid)
if ppid == 1:
LOG.debug("killing dhclient with pid=%s", pid)
os.kill(pid, signal.SIGKILL)
daemonized = True
break
time.sleep(0.01)
if not daemonized:
LOG.error(
"dhclient(pid=%s, parentpid=%s) failed to daemonize after %s "
"seconds",
pid_content,
ppid,
0.01 * 1000,
)
if dhcp_log_func is not None:
dhcp_log_func(out, err)
return parse_dhcp_lease_file(lease_file)
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 list of dicts of representing the dhcp leases parsed from the
dhcp.leases file or empty list.
"""
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)
# Wait for pid file and lease file to appear, and for the process
# named by the pid file to daemonize (have pid 1 as its parent). If we
# try to read the lease file before daemonization happens, we might try
# to read it before the dhclient has actually written it. We also have
# to wait until the dhclient has become a daemon so we can be sure to
# kill the correct process, thus freeing cleandir to be deleted back
# up the callstack.
missing = util.wait_for_files(
[pid_file, lease_file], maxwait=5, naplen=0.01)
if missing:
LOG.warning("dhclient did not produce expected files: %s",
', '.join(os.path.basename(f) for f in missing))
return []
ppid = 'unknown'
for _ in range(0, 1000):
pid_content = util.load_file(pid_file).strip()
try:
pid = int(pid_content)
except ValueError:
pass
else:
ppid = util.get_proc_ppid(pid)
if ppid == 1:
LOG.debug('killing dhclient with pid=%s', pid)
os.kill(pid, signal.SIGKILL)
return parse_dhcp_lease_file(lease_file)
time.sleep(0.01)
LOG.error(
'dhclient(pid=%s, parentpid=%s) failed to daemonize after %s seconds',
pid_content, ppid, 0.01 * 1000
)
return parse_dhcp_lease_file(lease_file)
