From 5291eafa412117b80ebbf645fc51559dd0b2caaf Mon Sep 17 00:00:00 2001 From: Mike Frysinger Date: Wed, 5 May 2021 15:53:03 -0400 Subject: ssh: move all ssh logic to a common place We had ssh logic sprinkled between two git modules, and neither was quite the right home for it. This largely moves the logic as-is to its new home. We'll leave major refactoring to followup commits. Bug: https://crbug.com/gerrit/12389 Change-Id: I300a8f7dba74f2bd132232a5eb1e856a8490e0e9 Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/305483 Reviewed-by: Chris Mcdonald Tested-by: Mike Frysinger --- ssh.py | 257 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 257 insertions(+) create mode 100644 ssh.py (limited to 'ssh.py') diff --git a/ssh.py b/ssh.py new file mode 100644 index 00000000..d06c4eb2 --- /dev/null +++ b/ssh.py @@ -0,0 +1,257 @@ +# 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 os +import re +import signal +import subprocess +import sys +import tempfile +try: + import threading as _threading +except ImportError: + import dummy_threading as _threading +import time + +import platform_utils +from repo_trace import Trace + + +_ssh_proxy_path = None +_ssh_sock_path = None +_ssh_clients = [] + + +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 subprocess.CalledProcessError: + print('fatal: unable to detect ssh version', file=sys.stderr) + sys.exit(1) + + +def proxy(): + global _ssh_proxy_path + if _ssh_proxy_path is None: + _ssh_proxy_path = os.path.join( + os.path.dirname(__file__), + 'git_ssh') + return _ssh_proxy_path + + +def add_client(p): + _ssh_clients.append(p) + + +def remove_client(p): + try: + _ssh_clients.remove(p) + except ValueError: + pass + + +def _terminate_clients(): + global _ssh_clients + for p in _ssh_clients: + try: + os.kill(p.pid, signal.SIGTERM) + p.wait() + except OSError: + pass + _ssh_clients = [] + + +_master_processes = [] +_master_keys = set() +_ssh_master = True +_master_keys_lock = None + + +def init(): + """Should be called once at the start of repo to init ssh master handling. + + At the moment, all we do is to create our lock. + """ + global _master_keys_lock + assert _master_keys_lock is None, "Should only call init once" + _master_keys_lock = _threading.Lock() + + +def _open_ssh(host, port=None): + global _ssh_master + + # 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 specifies a different host from the + # one that was passed to repo init. + _master_keys_lock.acquire() + try: + + # 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 _master_keys: + return True + + if not _ssh_master 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' % 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'] + try: + Trace(': %s', ' '.join(check_command)) + 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. + _master_keys.add(key) + 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:] + try: + Trace(': %s', ' '.join(command)) + p = subprocess.Popen(command) + except Exception as e: + _ssh_master = False + 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 + + _master_processes.append(p) + _master_keys.add(key) + return True + finally: + _master_keys_lock.release() + + +def close(): + global _master_keys_lock + + _terminate_clients() + + for p in _master_processes: + try: + os.kill(p.pid, signal.SIGTERM) + p.wait() + except OSError: + pass + del _master_processes[:] + _master_keys.clear() + + d = sock(create=False) + if d: + try: + platform_utils.rmdir(os.path.dirname(d)) + except OSError: + pass + + # We're done with the lock, so we can delete it. + _master_keys_lock = None + + +URI_SCP = re.compile(r'^([^@:]*@?[^:/]{1,}):') +URI_ALL = re.compile(r'^([a-z][a-z+-]*)://([^@/]*@?[^/]*)/') + + +def preconnect(url): + 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 _open_ssh(host, port) + return False + + m = URI_SCP.match(url) + if m: + host = m.group(1) + return _open_ssh(host) + + return False + +def sock(create=True): + global _ssh_sock_path + if _ssh_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 + _ssh_sock_path = os.path.join( + tempfile.mkdtemp('', 'ssh-', tmp_dir), + 'master-' + tokens) + return _ssh_sock_path -- cgit v1.2.3-54-g00ecf