#
# Copyright 2007 Google Inc. Released under the GPL v2

"""
This module defines the SSHHost class.

Implementation details:
You should import the "hosts" package instead of importing each type of host.

        SSHHost: a remote machine with a ssh access
"""

import re, logging
from autotest_lib.client.common_lib import error, pxssh
from autotest_lib.server import utils
from autotest_lib.server.hosts import abstract_ssh


class SSHHost(abstract_ssh.AbstractSSHHost):
    """
    This class represents a remote machine controlled through an ssh
    session on which you can run programs.

    It is not the machine autoserv is running on. The machine must be
    configured for password-less login, for example through public key
    authentication.

    It includes support for controlling the machine through a serial
    console on which you can run programs. If such a serial console is
    set up on the machine then capabilities such as hard reset and
    boot strap monitoring are available. If the machine does not have a
    serial console available then ordinary SSH-based commands will
    still be available, but attempts to use extensions such as
    console logging or hard reset will fail silently.

    Implementation details:
    This is a leaf class in an abstract class hierarchy, it must
    implement the unimplemented methods in parent classes.
    """

    def _initialize(self, hostname, *args, **dargs):
        """
        Construct a SSHHost object

        Args:
                hostname: network hostname or address of remote machine
        """
        super(SSHHost, self)._initialize(hostname=hostname, *args, **dargs)
        self.setup_ssh()


    def ssh_command(self, connect_timeout=30, options='', alive_interval=300):
        """
        Construct an ssh command with proper args for this host.

        @param connect_timeout: connection timeout (in seconds)
        @param options: SSH options
        @param alive_interval: SSH Alive interval.

        """
        options = "%s %s" % (options, self.master_ssh_option)
        base_cmd = self.make_ssh_command(user=self.user, port=self.port,
                                         opts=options,
                                         hosts_file=self.known_hosts_file,
                                         connect_timeout=connect_timeout,
                                         alive_interval=alive_interval)
        return "%s %s" % (base_cmd, self.hostname)


    def _run(self, command, timeout, ignore_status,
             stdout, stderr, connect_timeout, env, options, stdin, args,
             ignore_timeout):
        """Helper function for run()."""
        ssh_cmd = self.ssh_command(connect_timeout, options)
        if not env.strip():
            env = ""
        else:
            env = "export %s;" % env
        for arg in args:
            command += ' "%s"' % utils.sh_escape(arg)
        full_cmd = '%s "%s %s"' % (ssh_cmd, env, utils.sh_escape(command))
        result = utils.run(full_cmd, timeout, True, stdout, stderr,
                           verbose=False, stdin=stdin,
                           stderr_is_expected=ignore_status,
                           ignore_timeout=ignore_timeout)

        if ignore_timeout and not result:
            return None

        # The error messages will show up in band (indistinguishable
        # from stuff sent through the SSH connection), so we have the
        # remote computer echo the message "Connected." before running
        # any command.  Since the following 2 errors have to do with
        # connecting, it's safe to do these checks.
        if result.exit_status == 255:
            if re.search(r'^ssh: connect to host .* port .*: '
                         r'Connection timed out\r$', result.stderr):
                raise error.AutoservSSHTimeout("ssh timed out", result)
            if "Permission denied." in result.stderr:
                msg = "ssh permission denied"
                raise error.AutoservSshPermissionDeniedError(msg, result)

        if not ignore_status and result.exit_status > 0:
            raise error.AutoservRunError("command execution error", result)

        return result


    def run(self, command, timeout=3600, ignore_status=False,
            stdout_tee=utils.TEE_TO_LOGS, stderr_tee=utils.TEE_TO_LOGS,
            connect_timeout=30, options='', stdin=None, verbose=True, args=(),
            ignore_timeout=False):
        """
        Run a command on the remote host.
        @see common_lib.hosts.host.run()

        @param connect_timeout: connection timeout (in seconds)
        @param options: string with additional ssh command options
        @param verbose: log the commands
        @param ignore_timeout: bool True if SSH command timeouts should be
                ignored.  Will return None on command timeout.

        @raises AutoservRunError: if the command failed
        @raises AutoservSSHTimeout: ssh connection has timed out
        """
        if verbose:
            logging.debug("Running (ssh) '%s'", command)

        # Start a master SSH connection if necessary.
        self.start_master_ssh()

        env = " ".join("=".join(pair) for pair in self.env.iteritems())
        try:
            return self._run(command, timeout, ignore_status,
                             stdout_tee, stderr_tee, connect_timeout, env,
                             options, stdin, args, ignore_timeout)
        except error.CmdError, cmderr:
            # We get a CmdError here only if there is timeout of that command.
            # Catch that and stuff it into AutoservRunError and raise it.
            timeout_message = str('Timeout encountered: %s' % cmderr.args[0])
            raise error.AutoservRunError(timeout_message, cmderr.args[1])


    def run_short(self, command, **kwargs):
        """
        Calls the run() command with a short default timeout.

        Takes the same arguments as does run(),
        with the exception of the timeout argument which
        here is fixed at 60 seconds.
        It returns the result of run.

        @param command: the command line string

        """
        return self.run(command, timeout=60, **kwargs)


    def run_grep(self, command, timeout=30, ignore_status=False,
                 stdout_ok_regexp=None, stdout_err_regexp=None,
                 stderr_ok_regexp=None, stderr_err_regexp=None,
                 connect_timeout=30):
        """
        Run a command on the remote host and look for regexp
        in stdout or stderr to determine if the command was
        successul or not.


        @param command: the command line string
        @param timeout: time limit in seconds before attempting to
                        kill the running process. The run() function
                        will take a few seconds longer than 'timeout'
                        to complete if it has to kill the process.
        @param ignore_status: do not raise an exception, no matter
                              what the exit code of the command is.
        @param stdout_ok_regexp: regexp that should be in stdout
                                 if the command was successul.
        @param stdout_err_regexp: regexp that should be in stdout
                                  if the command failed.
        @param stderr_ok_regexp: regexp that should be in stderr
                                 if the command was successul.
        @param stderr_err_regexp: regexp that should be in stderr
                                 if the command failed.
        @param connect_timeout: connection timeout (in seconds)

        Returns:
                if the command was successul, raises an exception
                otherwise.

        Raises:
                AutoservRunError:
                - the exit code of the command execution was not 0.
                - If stderr_err_regexp is found in stderr,
                - If stdout_err_regexp is found in stdout,
                - If stderr_ok_regexp is not found in stderr.
                - If stdout_ok_regexp is not found in stdout,
        """

        # We ignore the status, because we will handle it at the end.
        result = self.run(command, timeout, ignore_status=True,
                          connect_timeout=connect_timeout)

        # Look for the patterns, in order
        for (regexp, stream) in ((stderr_err_regexp, result.stderr),
                                 (stdout_err_regexp, result.stdout)):
            if regexp and stream:
                err_re = re.compile (regexp)
                if err_re.search(stream):
                    raise error.AutoservRunError(
                        '%s failed, found error pattern: "%s"' % (command,
                                                                regexp), result)

        for (regexp, stream) in ((stderr_ok_regexp, result.stderr),
                                 (stdout_ok_regexp, result.stdout)):
            if regexp and stream:
                ok_re = re.compile (regexp)
                if ok_re.search(stream):
                    if ok_re.search(stream):
                        return

        if not ignore_status and result.exit_status > 0:
            raise error.AutoservRunError("command execution error", result)


    def setup_ssh_key(self):
        """Setup SSH Key"""
        logging.debug('Performing SSH key setup on %s:%d as %s.',
                      self.hostname, self.port, self.user)

        try:
            host = pxssh.pxssh()
            host.login(self.hostname, self.user, self.password,
                        port=self.port)
            public_key = utils.get_public_key()

            host.sendline('mkdir -p ~/.ssh')
            host.prompt()
            host.sendline('chmod 700 ~/.ssh')
            host.prompt()
            host.sendline("echo '%s' >> ~/.ssh/authorized_keys; " %
                            public_key)
            host.prompt()
            host.sendline('chmod 600 ~/.ssh/authorized_keys')
            host.prompt()
            host.logout()

            logging.debug('SSH key setup complete.')

        except:
            logging.debug('SSH key setup has failed.')
            try:
                host.logout()
            except:
                pass


    def setup_ssh(self):
        """Setup SSH"""
        if self.password:
            try:
                self.ssh_ping()
            except error.AutoservSshPingHostError:
                self.setup_ssh_key()