| # Copyright (C) 2008 The Android Open Source Project |
| # |
| # Licensed under the Apache License, Version 2.0 (the "License"); |
| # you may not use this file except in compliance with the License. |
| # You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, software |
| # distributed under the License is distributed on an "AS IS" BASIS, |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| # See the License for the specific language governing permissions and |
| # limitations under the License. |
| |
| """Common SSH management logic.""" |
| |
| import functools |
| import multiprocessing |
| import os |
| import re |
| import signal |
| import subprocess |
| import sys |
| import tempfile |
| import time |
| |
| import platform_utils |
| from repo_trace import Trace |
| |
| |
| PROXY_PATH = os.path.join(os.path.dirname(__file__), 'git_ssh') |
| |
| |
| def _run_ssh_version(): |
| """run ssh -V to display the version number""" |
| return subprocess.check_output(['ssh', '-V'], stderr=subprocess.STDOUT).decode() |
| |
| |
| def _parse_ssh_version(ver_str=None): |
| """parse a ssh version string into a tuple""" |
| if ver_str is None: |
| ver_str = _run_ssh_version() |
| m = re.match(r'^OpenSSH_([0-9.]+)(p[0-9]+)?\s', ver_str) |
| if m: |
| return tuple(int(x) for x in m.group(1).split('.')) |
| else: |
| return () |
| |
| |
| @functools.lru_cache(maxsize=None) |
| def version(): |
| """return ssh version as a tuple""" |
| try: |
| return _parse_ssh_version() |
| except FileNotFoundError: |
| print('fatal: ssh not installed', file=sys.stderr) |
| sys.exit(1) |
| except subprocess.CalledProcessError: |
| print('fatal: unable to detect ssh version', file=sys.stderr) |
| sys.exit(1) |
| |
| |
| URI_SCP = re.compile(r'^([^@:]*@?[^:/]{1,}):') |
| URI_ALL = re.compile(r'^([a-z][a-z+-]*)://([^@/]*@?[^/]*)/') |
| |
| |
| class ProxyManager: |
| """Manage various ssh clients & masters that we spawn. |
| |
| This will take care of sharing state between multiprocessing children, and |
| make sure that if we crash, we don't leak any of the ssh sessions. |
| |
| The code should work with a single-process scenario too, and not add too much |
| overhead due to the manager. |
| """ |
| |
| # Path to the ssh program to run which will pass our master settings along. |
| # Set here more as a convenience API. |
| proxy = PROXY_PATH |
| |
| def __init__(self, manager): |
| # Protect access to the list of active masters. |
| self._lock = multiprocessing.Lock() |
| # List of active masters (pid). These will be spawned on demand, and we are |
| # responsible for shutting them all down at the end. |
| self._masters = manager.list() |
| # Set of active masters indexed by "host:port" information. |
| # The value isn't used, but multiprocessing doesn't provide a set class. |
| self._master_keys = manager.dict() |
| # Whether ssh masters are known to be broken, so we give up entirely. |
| self._master_broken = manager.Value('b', False) |
| # List of active ssh sesssions. Clients will be added & removed as |
| # connections finish, so this list is just for safety & cleanup if we crash. |
| self._clients = manager.list() |
| # Path to directory for holding master sockets. |
| self._sock_path = None |
| |
| def __enter__(self): |
| """Enter a new context.""" |
| return self |
| |
| def __exit__(self, exc_type, exc_value, traceback): |
| """Exit a context & clean up all resources.""" |
| self.close() |
| |
| def add_client(self, proc): |
| """Track a new ssh session.""" |
| self._clients.append(proc.pid) |
| |
| def remove_client(self, proc): |
| """Remove a completed ssh session.""" |
| try: |
| self._clients.remove(proc.pid) |
| except ValueError: |
| pass |
| |
| def add_master(self, proc): |
| """Track a new master connection.""" |
| self._masters.append(proc.pid) |
| |
| def _terminate(self, procs): |
| """Kill all |procs|.""" |
| for pid in procs: |
| try: |
| os.kill(pid, signal.SIGTERM) |
| os.waitpid(pid, 0) |
| except OSError: |
| pass |
| |
| # The multiprocessing.list() API doesn't provide many standard list() |
| # methods, so we have to manually clear the list. |
| while True: |
| try: |
| procs.pop(0) |
| except: |
| break |
| |
| def close(self): |
| """Close this active ssh session. |
| |
| Kill all ssh clients & masters we created, and nuke the socket dir. |
| """ |
| self._terminate(self._clients) |
| self._terminate(self._masters) |
| |
| d = self.sock(create=False) |
| if d: |
| try: |
| platform_utils.rmdir(os.path.dirname(d)) |
| except OSError: |
| pass |
| |
| def _open_unlocked(self, host, port=None): |
| """Make sure a ssh master session exists for |host| & |port|. |
| |
| If one doesn't exist already, we'll create it. |
| |
| We won't grab any locks, so the caller has to do that. This helps keep the |
| business logic of actually creating the master separate from grabbing locks. |
| """ |
| # Check to see whether we already think that the master is running; if we |
| # think it's already running, return right away. |
| if port is not None: |
| key = '%s:%s' % (host, port) |
| else: |
| key = host |
| |
| if key in self._master_keys: |
| return True |
| |
| if self._master_broken.value or 'GIT_SSH' in os.environ: |
| # Failed earlier, so don't retry. |
| return False |
| |
| # We will make two calls to ssh; this is the common part of both calls. |
| command_base = ['ssh', '-o', 'ControlPath %s' % self.sock(), host] |
| if port is not None: |
| command_base[1:1] = ['-p', str(port)] |
| |
| # Since the key wasn't in _master_keys, we think that master isn't running. |
| # ...but before actually starting a master, we'll double-check. This can |
| # be important because we can't tell that that 'git@myhost.com' is the same |
| # as 'myhost.com' where "User git" is setup in the user's ~/.ssh/config file. |
| check_command = command_base + ['-O', 'check'] |
| with Trace('Call to ssh (check call): %s', ' '.join(check_command)): |
| try: |
| check_process = subprocess.Popen(check_command, |
| stdout=subprocess.PIPE, |
| stderr=subprocess.PIPE) |
| check_process.communicate() # read output, but ignore it... |
| isnt_running = check_process.wait() |
| |
| if not isnt_running: |
| # Our double-check found that the master _was_ infact running. Add to |
| # the list of keys. |
| self._master_keys[key] = True |
| return True |
| except Exception: |
| # Ignore excpetions. We we will fall back to the normal command and |
| # print to the log there. |
| pass |
| |
| command = command_base[:1] + ['-M', '-N'] + command_base[1:] |
| p = None |
| try: |
| with Trace('Call to ssh: %s', ' '.join(command)): |
| p = subprocess.Popen(command) |
| except Exception as e: |
| self._master_broken.value = True |
| print('\nwarn: cannot enable ssh control master for %s:%s\n%s' |
| % (host, port, str(e)), file=sys.stderr) |
| return False |
| |
| time.sleep(1) |
| ssh_died = (p.poll() is not None) |
| if ssh_died: |
| return False |
| |
| self.add_master(p) |
| self._master_keys[key] = True |
| return True |
| |
| def _open(self, host, port=None): |
| """Make sure a ssh master session exists for |host| & |port|. |
| |
| If one doesn't exist already, we'll create it. |
| |
| This will obtain any necessary locks to avoid inter-process races. |
| """ |
| # Bail before grabbing the lock if we already know that we aren't going to |
| # try creating new masters below. |
| if sys.platform in ('win32', 'cygwin'): |
| return False |
| |
| # Acquire the lock. This is needed to prevent opening multiple masters for |
| # the same host when we're running "repo sync -jN" (for N > 1) _and_ the |
| # manifest <remote fetch="ssh://xyz"> specifies a different host from the |
| # one that was passed to repo init. |
| with self._lock: |
| return self._open_unlocked(host, port) |
| |
| def preconnect(self, url): |
| """If |uri| will create a ssh connection, setup the ssh master for it.""" |
| m = URI_ALL.match(url) |
| if m: |
| scheme = m.group(1) |
| host = m.group(2) |
| if ':' in host: |
| host, port = host.split(':') |
| else: |
| port = None |
| if scheme in ('ssh', 'git+ssh', 'ssh+git'): |
| return self._open(host, port) |
| return False |
| |
| m = URI_SCP.match(url) |
| if m: |
| host = m.group(1) |
| return self._open(host) |
| |
| return False |
| |
| def sock(self, create=True): |
| """Return the path to the ssh socket dir. |
| |
| This has all the master sockets so clients can talk to them. |
| """ |
| if self._sock_path is None: |
| if not create: |
| return None |
| tmp_dir = '/tmp' |
| if not os.path.exists(tmp_dir): |
| tmp_dir = tempfile.gettempdir() |
| if version() < (6, 7): |
| tokens = '%r@%h:%p' |
| else: |
| tokens = '%C' # hash of %l%h%p%r |
| self._sock_path = os.path.join( |
| tempfile.mkdtemp('', 'ssh-', tmp_dir), |
| 'master-' + tokens) |
| return self._sock_path |