#!/usr/bin/env python3 """Remote access utilities, via ssh & scp.""" import optparse import os import posixpath import re import shlex import sys import time import subprocess # Get relative imports to work when the package is not installed on the PYTHONPATH. if __name__ == "__main__" and __package__ is None: sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))) _IS_WINDOWS = sys.platform == "win32" or sys.platform == "cygwin" _OPERATIONS = ["shell", "copy_to", "copy_from"] _SSH_CONNECTION_ERRORS = [ "Connection refused", "Connection timed out during banner exchange", "Permission denied", "System is booting up.", "ssh_exchange_identification: read: Connection reset by peer", ] def posix_path(path): """Return posix path, used on Windows since scp requires posix style paths.""" # If path is already quoted, we need to remove the quotes before calling path_quote = "\'" if path.startswith("\'") else "" path_quote = "\"" if path.startswith("\"") else path_quote if path_quote: path = path[1:-1] drive, new_path = os.path.splitdrive(path) if drive: new_path = posixpath.join("/cygdrive", drive.split(":")[0], *re.split("/|\\\\", new_path)) return "{quote}{path}{quote}".format(quote=path_quote, path=new_path) class RemoteOperations(object): # pylint: disable=too-many-instance-attributes """Class to support remote operations.""" def __init__( # pylint: disable=too-many-arguments self, user_host, ssh_connection_options=None, ssh_options=None, scp_options=None, retries=0, retry_sleep=0, debug=False, shell_binary="/bin/bash", use_shell=False): """Initialize RemoteOperations.""" self.user_host = user_host self.ssh_connection_options = ssh_connection_options if ssh_connection_options else "" self.ssh_options = ssh_options if ssh_options else "" self.scp_options = scp_options if scp_options else "" self.retries = retries self.retry_sleep = retry_sleep self.debug = debug self.shell_binary = shell_binary self.use_shell = use_shell # Check if we can remotely access the host. self._access_code, self._access_buff = self._remote_access() def _call(self, cmd): if self.debug: print(cmd) # If use_shell is False we need to split the command up into a list. if not self.use_shell: cmd = shlex.split(cmd) # Use a common pipe for stdout & stderr for logging. process = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, shell=self.use_shell) buff_stdout, _ = process.communicate() return process.poll(), buff_stdout.decode("utf-8", "replace") def _remote_access(self): """Check if a remote session is possible.""" cmd = "ssh {} {} {} date".format(self.ssh_connection_options, self.ssh_options, self.user_host) attempt_num = 0 buff = "" while True: ret, buff = self._call(cmd) # Ignore any connection errors before sshd has fully initialized. if not ret and not any(ssh_error in buff for ssh_error in _SSH_CONNECTION_ERRORS): return ret, buff attempt_num += 1 if attempt_num > self.retries: break if self.debug: print("Failed remote attempt {}, retrying in {} seconds".format( attempt_num, self.retry_sleep)) time.sleep(self.retry_sleep) return ret, buff def _perform_operation(self, cmd): return self._call(cmd) def access_established(self): """Return True if initial access was established.""" return not self._access_code def access_info(self): """Return the return code and output buffer from initial access attempt(s).""" return self._access_code, self._access_buff @staticmethod def ssh_error(message): """Return True if the error message is generated from the ssh client. This can help determine if an error is due to a remote operation failing or an ssh related issue, like a connection issue. """ return message.startswith("ssh:") def operation( # pylint: disable=too-many-branches self, operation_type, operation_param, operation_dir=None): """Execute Main entry for remote operations. Returns (code, output). 'operation_type' supports remote shell and copy operations. 'operation_param' can either be a list or string of commands or files. 'operation_dir' is '.' if unspecified for 'copy_*'. """ if not self.access_established(): return self.access_info() # File names with a space must be quoted, since we permit the # the file names to be either a string or a list. if operation_type.startswith("copy") and isinstance(operation_param, str): operation_param = shlex.split(operation_param, posix=not _IS_WINDOWS) cmds = [] if operation_type == "shell": if operation_dir is not None: operation_param = "cd {}; {}".format(operation_dir, operation_param) dollar = "" if re.search("\"|'", operation_param): # To ensure any quotes in operation_param are handled correctly when # invoking the operation_param, escape with \ and add $ in the front. # See https://stackoverflow.com/questions/8254120/ # how-to-escape-a-single-quote-in-single-quote-string-in-bash operation_param = "{}".format(operation_param.replace("'", r"\'")) operation_param = "{}".format(operation_param.replace("\"", r"\"")) dollar = "$" cmd = "ssh {} {} {} {} -c \"{}'{}'\"".format(self.ssh_connection_options, self.ssh_options, self.user_host, self.shell_binary, dollar, operation_param) cmds.append(cmd) elif operation_type == "copy_to": cmd = "scp -r {} {} ".format(self.ssh_connection_options, self.scp_options) # To support spaces in the filename or directory, we quote them one at a time. for copy_file in operation_param: # Quote file on Posix. quote = "\"" if not _IS_WINDOWS else "" cmd += "{quote}{file}{quote} ".format(quote=quote, file=posix_path(copy_file)) operation_dir = operation_dir if operation_dir else "" cmd += " {}:{}".format(self.user_host, posix_path(operation_dir)) cmds.append(cmd) elif operation_type == "copy_from": operation_dir = operation_dir if operation_dir else "." if not os.path.isdir(operation_dir): raise ValueError("Local directory '{}' does not exist.".format(operation_dir)) # We support multiple files being copied from the remote host # by invoking scp for each file specified. # Note - this is a method which scp does not support directly. for copy_file in operation_param: copy_file = posix_path(copy_file) cmd = "scp -r {} {} {}:".format(self.ssh_connection_options, self.scp_options, self.user_host) # Quote (on Posix), and escape the file if there are spaces. # Note - we do not support other non-ASCII characters in a file name. quote = "\"" if not _IS_WINDOWS else "" if " " in copy_file: copy_file = re.escape("{quote}{file}{quote}".format( quote=quote, file=copy_file)) cmd += "{} {}".format(copy_file, posix_path(operation_dir)) cmds.append(cmd) else: raise ValueError("Invalid operation '{}' specified, choose from {}.".format( operation_type, _OPERATIONS)) final_ret = 0 buff = "" for cmd in cmds: ret, new_buff = self._perform_operation(cmd) buff += new_buff final_ret = final_ret or ret return final_ret, buff def shell(self, operation_param, operation_dir=None): """Provide helper for remote shell operations.""" return self.operation(operation_type="shell", operation_param=operation_param, operation_dir=operation_dir) def copy_to(self, operation_param, operation_dir=None): """Provide helper for remote copy_to operations.""" return self.operation(operation_type="copy_to", operation_param=operation_param, operation_dir=operation_dir) def copy_from(self, operation_param, operation_dir=None): """Provide helper for remote copy_from operations.""" return self.operation(operation_type="copy_from", operation_param=operation_param, operation_dir=operation_dir) def main(): # pylint: disable=too-many-branches,too-many-statements """Execute Main program.""" parser = optparse.OptionParser(description=__doc__) control_options = optparse.OptionGroup(parser, "Control options") shell_options = optparse.OptionGroup(parser, "Shell options") copy_options = optparse.OptionGroup(parser, "Copy options") parser.add_option( "--userHost", dest="user_host", default=None, help=("User and remote host to execute commands on [REQUIRED]." " Examples, 'user@1.2.3.4' or 'user@myhost.com'.")) parser.add_option( "--operation", dest="operation", default="shell", choices=_OPERATIONS, help=("Remote operation to perform, choose one of '{}'," " defaults to '%default'.".format(", ".join(_OPERATIONS)))) control_options.add_option( "--sshConnectionOptions", dest="ssh_connection_options", default=None, action="append", help=("SSH connection options which are common to ssh and scp." " More than one option can be specified either" " in one quoted string or by specifying" " this option more than once. Example options:" " '-i $HOME/.ssh/access.pem -o ConnectTimeout=10" " -o ConnectionAttempts=10'")) control_options.add_option( "--sshOptions", dest="ssh_options", default=None, action="append", help=("SSH specific options." " More than one option can be specified either" " in one quoted string or by specifying" " this option more than once. Example options:" " '-t' or '-T'")) control_options.add_option( "--scpOptions", dest="scp_options", default=None, action="append", help=("SCP specific options." " More than one option can be specified either" " in one quoted string or by specifying" " this option more than once. Example options:" " '-l 5000'")) control_options.add_option( "--retries", dest="retries", type=int, default=0, help=("Number of retries to attempt for operation," " defaults to '%default'.")) control_options.add_option( "--retrySleep", dest="retry_sleep", type=int, default=10, help=("Number of seconds to wait between retries," " defaults to '%default'.")) control_options.add_option("--debug", dest="debug", action="store_true", default=False, help="Provides debug output.") control_options.add_option("--verbose", dest="verbose", action="store_true", default=False, help="Print exit status and output at end.") shell_options.add_option( "--commands", dest="remote_commands", default=None, action="append", help=("Commands to excute on the remote host. The" " commands must be separated by a ';' and can either" " be specifed in a quoted string or by specifying" " this option more than once. A ';' will be added" " between commands when this option is specifed" " more than once.")) shell_options.add_option( "--commandDir", dest="command_dir", default=None, help=("Working directory on remote to execute commands" " form. Defaults to remote login directory.")) copy_options.add_option( "--file", dest="files", default=None, action="append", help=("The file to copy to/from remote host. To" " support spaces in the file, each file must be" " specified using this option more than once.")) copy_options.add_option( "--remoteDir", dest="remote_dir", default=None, help=("Remote directory to copy to, only applies when" " operation is 'copy_to'. Defaults to the login" " directory on the remote host.")) copy_options.add_option( "--localDir", dest="local_dir", default=".", help=("Local directory to copy to, only applies when" " operation is 'copy_from'. Defaults to the" " current directory, '%default'.")) parser.add_option_group(control_options) parser.add_option_group(shell_options) parser.add_option_group(copy_options) (options, _) = parser.parse_args() if not getattr(options, "user_host", None): parser.print_help() parser.error("Missing required option") if options.operation == "shell": if not getattr(options, "remote_commands", None): parser.print_help() parser.error("Missing required '{}' option '{}'".format(options.operation, "--commands")) operation_param = ";".join(options.remote_commands) operation_dir = options.command_dir else: if not getattr(options, "files", None): parser.print_help() parser.error("Missing required '{}' option '{}'".format(options.operation, "--file")) operation_param = options.files if options.operation == "copy_to": operation_dir = options.remote_dir else: operation_dir = options.local_dir if not options.ssh_connection_options: ssh_connection_options = None else: ssh_connection_options = " ".join(options.ssh_connection_options) if not options.ssh_options: ssh_options = None else: ssh_options = " ".join(options.ssh_options) if not options.scp_options: scp_options = None else: scp_options = " ".join(options.scp_options) remote_op = RemoteOperations( user_host=options.user_host, ssh_connection_options=ssh_connection_options, ssh_options=ssh_options, scp_options=scp_options, retries=options.retries, retry_sleep=options.retry_sleep, debug=options.debug) ret_code, buff = remote_op.operation(options.operation, operation_param, operation_dir) if options.verbose: print("Return code: {} for command {}".format(ret_code, sys.argv)) print(buff) sys.exit(ret_code) if __name__ == "__main__": main()