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"""Cache for SSH tunnels."""
import collections
import os
import subprocess
import threading
import time
import weakref
Context = collections.namedtuple('Context', (
'uri',
'interface',
'local_socket',
'remote_socket',
'username',
'hostname',
'identity_file',
))
class Portal(collections.MutableMapping):
"""Expiring container for tunnels."""
def __init__(self, sweap=25):
"""Construct portal, reap tunnels every sweap seconds."""
self.data = collections.OrderedDict()
self.sweap = sweap
self.ttl = sweap * 2
self.lock = threading.RLock()
self._schedule_reaper()
def __getitem__(self, key):
"""Given uri return tunnel and update TTL."""
with self.lock:
value, _ = self.data[key]
self.data[key] = (value, time.time() + self.ttl)
self.data.move_to_end(key)
return value
def __setitem__(self, key, value):
"""Store given tunnel keyed with uri."""
if not isinstance(value, Tunnel):
raise ValueError('Portals only support Tunnels.')
with self.lock:
self.data[key] = (value, time.time() + self.ttl)
self.data.move_to_end(key)
def __delitem__(self, key):
"""Remove and close tunnel from portal."""
with self.lock:
value, _ = self.data[key]
del self.data[key]
value.close(key)
del value
def __iter__(self):
"""Iterate tunnels."""
with self.lock:
values = self.data.values()
for tunnel, _ in values:
yield tunnel
def __len__(self):
"""Return number of tunnels in portal."""
with self.lock:
return len(self.data)
def _schedule_reaper(self):
timer = threading.Timer(interval=self.sweap, function=self.reap)
timer.setName('PortalReaper')
timer.setDaemon(True)
timer.start()
def reap(self):
"""Remove tunnels who's TTL has expired."""
now = time.time()
with self.lock:
reaped_data = self.data.copy()
for entry in reaped_data.items():
if entry[1][1] < now:
del self.data[entry[0]]
else:
# StopIteration as soon as possible
break
self._schedule_reaper()
class Tunnel(object):
"""SSH tunnel."""
def __init__(self, context):
"""Construct Tunnel."""
self.context = context
self._tunnel = None
def bore(self, id):
"""Create SSH tunnel from given context."""
cmd = [
'ssh',
'-nNT',
'-L',
'{}:{}'.format(self.context.local_socket,
self.context.remote_socket),
'-i',
self.context.identity_file,
'ssh://{}@{}'.format(self.context.username, self.context.hostname),
]
if os.environ.get('PODMAN_DEBUG'):
cmd.append('-vvv')
self._tunnel = subprocess.Popen(cmd, close_fds=True)
for i in range(5):
if os.path.exists(self.context.local_socket):
break
time.sleep(1)
else:
raise TimeoutError('Failed to create tunnel using: {}'.format(
' '.join(cmd)))
weakref.finalize(self, self.close, id)
return self
def close(self, id):
"""Close SSH tunnel."""
if self._tunnel is None:
return
self._tunnel.kill()
self._tunnel.wait(300)
os.remove(self.context.local_socket)
self._tunnel = None
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