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      1 import os, time, socket, shutil, glob, logging, traceback, tempfile, re
      2 import subprocess
      3 
      4 from multiprocessing import Lock
      5 from autotest_lib.client.common_lib import autotemp, error
      6 from autotest_lib.server import utils, autotest
      7 from autotest_lib.server.hosts import remote
      8 from autotest_lib.server.hosts import rpc_server_tracker
      9 from autotest_lib.client.common_lib.global_config import global_config
     10 
     11 # pylint: disable-msg=C0111
     12 
     13 get_value = global_config.get_config_value
     14 enable_master_ssh = get_value('AUTOSERV', 'enable_master_ssh', type=bool,
     15                               default=False)
     16 
     17 
     18 class AbstractSSHHost(remote.RemoteHost):
     19     """
     20     This class represents a generic implementation of most of the
     21     framework necessary for controlling a host via ssh. It implements
     22     almost all of the abstract Host methods, except for the core
     23     Host.run method.
     24     """
     25     VERSION_PREFIX = ''
     26 
     27     def _initialize(self, hostname, user="root", port=22, password="",
     28                     is_client_install_supported=True, host_attributes={},
     29                     *args, **dargs):
     30         super(AbstractSSHHost, self)._initialize(hostname=hostname,
     31                                                  *args, **dargs)
     32         # IP address is retrieved only on demand. Otherwise the host
     33         # initialization will fail for host is not online.
     34         self._ip = None
     35         self.user = user
     36         self.port = port
     37         self.password = password
     38         self._is_client_install_supported = is_client_install_supported
     39         self._use_rsync = None
     40         self.known_hosts_file = tempfile.mkstemp()[1]
     41         self._rpc_server_tracker = rpc_server_tracker.RpcServerTracker(self);
     42 
     43         """
     44         Master SSH connection background job, socket temp directory and socket
     45         control path option. If master-SSH is enabled, these fields will be
     46         initialized by start_master_ssh when a new SSH connection is initiated.
     47         """
     48         self.master_ssh_job = None
     49         self.master_ssh_tempdir = None
     50         self.master_ssh_option = ''
     51 
     52         # Create a Lock to protect against race conditions.
     53         self._lock = Lock()
     54 
     55         self.host_attributes = host_attributes
     56 
     57 
     58     @property
     59     def ip(self):
     60         """@return IP address of the host.
     61         """
     62         if not self._ip:
     63             self._ip = socket.getaddrinfo(self.hostname, None)[0][4][0]
     64         return self._ip
     65 
     66 
     67     @property
     68     def is_client_install_supported(self):
     69         """"
     70         Returns True if the host supports autotest client installs, False
     71         otherwise.
     72         """
     73         return self._is_client_install_supported
     74 
     75 
     76     @property
     77     def rpc_server_tracker(self):
     78         """"
     79         @return The RPC server tracker associated with this host.
     80         """
     81         return self._rpc_server_tracker
     82 
     83 
     84     def make_ssh_command(self, user="root", port=22, opts='',
     85                          hosts_file='/dev/null',
     86                          connect_timeout=30, alive_interval=300):
     87         base_command = ("/usr/bin/ssh -a -x %s -o StrictHostKeyChecking=no "
     88                         "-o UserKnownHostsFile=%s -o BatchMode=yes "
     89                         "-o ConnectTimeout=%d -o ServerAliveInterval=%d "
     90                         "-l %s -p %d")
     91         assert isinstance(connect_timeout, (int, long))
     92         assert connect_timeout > 0 # can't disable the timeout
     93         return base_command % (opts, hosts_file, connect_timeout,
     94                                alive_interval, user, port)
     95 
     96 
     97     def use_rsync(self):
     98         if self._use_rsync is not None:
     99             return self._use_rsync
    100 
    101         # Check if rsync is available on the remote host. If it's not,
    102         # don't try to use it for any future file transfers.
    103         self._use_rsync = self._check_rsync()
    104         if not self._use_rsync:
    105             logging.warning("rsync not available on remote host %s -- disabled",
    106                          self.hostname)
    107         return self._use_rsync
    108 
    109 
    110     def _check_rsync(self):
    111         """
    112         Check if rsync is available on the remote host.
    113         """
    114         try:
    115             self.run("rsync --version", stdout_tee=None, stderr_tee=None)
    116         except error.AutoservRunError:
    117             return False
    118         return True
    119 
    120 
    121     def _encode_remote_paths(self, paths, escape=True):
    122         """
    123         Given a list of file paths, encodes it as a single remote path, in
    124         the style used by rsync and scp.
    125         """
    126         if escape:
    127             paths = [utils.scp_remote_escape(path) for path in paths]
    128 
    129         remote = self.hostname
    130 
    131         # rsync and scp require IPv6 brackets, even when there isn't any
    132         # trailing port number (ssh doesn't support IPv6 brackets).
    133         # In the Python >= 3.3 future, 'import ipaddress' will parse addresses.
    134         if re.search(r':.*:', remote):
    135             remote = '[%s]' % remote
    136 
    137         return '%s@%s:"%s"' % (self.user, remote, " ".join(paths))
    138 
    139 
    140     def _make_rsync_cmd(self, sources, dest, delete_dest, preserve_symlinks):
    141         """
    142         Given a list of source paths and a destination path, produces the
    143         appropriate rsync command for copying them. Remote paths must be
    144         pre-encoded.
    145         """
    146         ssh_cmd = self.make_ssh_command(user=self.user, port=self.port,
    147                                         opts=self.master_ssh_option,
    148                                         hosts_file=self.known_hosts_file)
    149         if delete_dest:
    150             delete_flag = "--delete"
    151         else:
    152             delete_flag = ""
    153         if preserve_symlinks:
    154             symlink_flag = ""
    155         else:
    156             symlink_flag = "-L"
    157         command = ("rsync %s %s --timeout=1800 --rsh='%s' -az --no-o --no-g "
    158                    "%s \"%s\"")
    159         return command % (symlink_flag, delete_flag, ssh_cmd,
    160                           " ".join(['"%s"' % p for p in sources]), dest)
    161 
    162 
    163     def _make_ssh_cmd(self, cmd):
    164         """
    165         Create a base ssh command string for the host which can be used
    166         to run commands directly on the machine
    167         """
    168         base_cmd = self.make_ssh_command(user=self.user, port=self.port,
    169                                          opts=self.master_ssh_option,
    170                                          hosts_file=self.known_hosts_file)
    171 
    172         return '%s %s "%s"' % (base_cmd, self.hostname, utils.sh_escape(cmd))
    173 
    174     def _make_scp_cmd(self, sources, dest):
    175         """
    176         Given a list of source paths and a destination path, produces the
    177         appropriate scp command for encoding it. Remote paths must be
    178         pre-encoded.
    179         """
    180         command = ("scp -rq %s -o StrictHostKeyChecking=no "
    181                    "-o UserKnownHostsFile=%s -P %d %s '%s'")
    182         return command % (self.master_ssh_option, self.known_hosts_file,
    183                           self.port, " ".join(sources), dest)
    184 
    185 
    186     def _make_rsync_compatible_globs(self, path, is_local):
    187         """
    188         Given an rsync-style path, returns a list of globbed paths
    189         that will hopefully provide equivalent behaviour for scp. Does not
    190         support the full range of rsync pattern matching behaviour, only that
    191         exposed in the get/send_file interface (trailing slashes).
    192 
    193         The is_local param is flag indicating if the paths should be
    194         interpreted as local or remote paths.
    195         """
    196 
    197         # non-trailing slash paths should just work
    198         if len(path) == 0 or path[-1] != "/":
    199             return [path]
    200 
    201         # make a function to test if a pattern matches any files
    202         if is_local:
    203             def glob_matches_files(path, pattern):
    204                 return len(glob.glob(path + pattern)) > 0
    205         else:
    206             def glob_matches_files(path, pattern):
    207                 result = self.run("ls \"%s\"%s" % (utils.sh_escape(path),
    208                                                    pattern),
    209                                   stdout_tee=None, ignore_status=True)
    210                 return result.exit_status == 0
    211 
    212         # take a set of globs that cover all files, and see which are needed
    213         patterns = ["*", ".[!.]*"]
    214         patterns = [p for p in patterns if glob_matches_files(path, p)]
    215 
    216         # convert them into a set of paths suitable for the commandline
    217         if is_local:
    218             return ["\"%s\"%s" % (utils.sh_escape(path), pattern)
    219                     for pattern in patterns]
    220         else:
    221             return [utils.scp_remote_escape(path) + pattern
    222                     for pattern in patterns]
    223 
    224 
    225     def _make_rsync_compatible_source(self, source, is_local):
    226         """
    227         Applies the same logic as _make_rsync_compatible_globs, but
    228         applies it to an entire list of sources, producing a new list of
    229         sources, properly quoted.
    230         """
    231         return sum((self._make_rsync_compatible_globs(path, is_local)
    232                     for path in source), [])
    233 
    234 
    235     def _set_umask_perms(self, dest):
    236         """
    237         Given a destination file/dir (recursively) set the permissions on
    238         all the files and directories to the max allowed by running umask.
    239         """
    240 
    241         # now this looks strange but I haven't found a way in Python to _just_
    242         # get the umask, apparently the only option is to try to set it
    243         umask = os.umask(0)
    244         os.umask(umask)
    245 
    246         max_privs = 0777 & ~umask
    247 
    248         def set_file_privs(filename):
    249             """Sets mode of |filename|.  Assumes |filename| exists."""
    250             file_stat = os.stat(filename)
    251 
    252             file_privs = max_privs
    253             # if the original file permissions do not have at least one
    254             # executable bit then do not set it anywhere
    255             if not file_stat.st_mode & 0111:
    256                 file_privs &= ~0111
    257 
    258             os.chmod(filename, file_privs)
    259 
    260         # try a bottom-up walk so changes on directory permissions won't cut
    261         # our access to the files/directories inside it
    262         for root, dirs, files in os.walk(dest, topdown=False):
    263             # when setting the privileges we emulate the chmod "X" behaviour
    264             # that sets to execute only if it is a directory or any of the
    265             # owner/group/other already has execute right
    266             for dirname in dirs:
    267                 os.chmod(os.path.join(root, dirname), max_privs)
    268 
    269             # Filter out broken symlinks as we go.
    270             for filename in filter(os.path.exists, files):
    271                 set_file_privs(os.path.join(root, filename))
    272 
    273 
    274         # now set privs for the dest itself
    275         if os.path.isdir(dest):
    276             os.chmod(dest, max_privs)
    277         else:
    278             set_file_privs(dest)
    279 
    280 
    281     def get_file(self, source, dest, delete_dest=False, preserve_perm=True,
    282                  preserve_symlinks=False):
    283         """
    284         Copy files from the remote host to a local path.
    285 
    286         Directories will be copied recursively.
    287         If a source component is a directory with a trailing slash,
    288         the content of the directory will be copied, otherwise, the
    289         directory itself and its content will be copied. This
    290         behavior is similar to that of the program 'rsync'.
    291 
    292         Args:
    293                 source: either
    294                         1) a single file or directory, as a string
    295                         2) a list of one or more (possibly mixed)
    296                                 files or directories
    297                 dest: a file or a directory (if source contains a
    298                         directory or more than one element, you must
    299                         supply a directory dest)
    300                 delete_dest: if this is true, the command will also clear
    301                              out any old files at dest that are not in the
    302                              source
    303                 preserve_perm: tells get_file() to try to preserve the sources
    304                                permissions on files and dirs
    305                 preserve_symlinks: try to preserve symlinks instead of
    306                                    transforming them into files/dirs on copy
    307 
    308         Raises:
    309                 AutoservRunError: the scp command failed
    310         """
    311         logging.debug('get_file. source: %s, dest: %s, delete_dest: %s,'
    312                       'preserve_perm: %s, preserve_symlinks:%s', source, dest,
    313                       delete_dest, preserve_perm, preserve_symlinks)
    314         # Start a master SSH connection if necessary.
    315         self.start_master_ssh()
    316 
    317         if isinstance(source, basestring):
    318             source = [source]
    319         dest = os.path.abspath(dest)
    320 
    321         # If rsync is disabled or fails, try scp.
    322         try_scp = True
    323         if self.use_rsync():
    324             logging.debug('Using Rsync.')
    325             try:
    326                 remote_source = self._encode_remote_paths(source)
    327                 local_dest = utils.sh_escape(dest)
    328                 rsync = self._make_rsync_cmd([remote_source], local_dest,
    329                                              delete_dest, preserve_symlinks)
    330                 utils.run(rsync)
    331                 try_scp = False
    332             except error.CmdError, e:
    333                 logging.warning("trying scp, rsync failed: %s", e)
    334 
    335         if try_scp:
    336             logging.debug('Trying scp.')
    337             # scp has no equivalent to --delete, just drop the entire dest dir
    338             if delete_dest and os.path.isdir(dest):
    339                 shutil.rmtree(dest)
    340                 os.mkdir(dest)
    341 
    342             remote_source = self._make_rsync_compatible_source(source, False)
    343             if remote_source:
    344                 # _make_rsync_compatible_source() already did the escaping
    345                 remote_source = self._encode_remote_paths(remote_source,
    346                                                           escape=False)
    347                 local_dest = utils.sh_escape(dest)
    348                 scp = self._make_scp_cmd([remote_source], local_dest)
    349                 try:
    350                     utils.run(scp)
    351                 except error.CmdError, e:
    352                     logging.debug('scp failed: %s', e)
    353                     raise error.AutoservRunError(e.args[0], e.args[1])
    354 
    355         if not preserve_perm:
    356             # we have no way to tell scp to not try to preserve the
    357             # permissions so set them after copy instead.
    358             # for rsync we could use "--no-p --chmod=ugo=rwX" but those
    359             # options are only in very recent rsync versions
    360             self._set_umask_perms(dest)
    361 
    362 
    363     def send_file(self, source, dest, delete_dest=False,
    364                   preserve_symlinks=False):
    365         """
    366         Copy files from a local path to the remote host.
    367 
    368         Directories will be copied recursively.
    369         If a source component is a directory with a trailing slash,
    370         the content of the directory will be copied, otherwise, the
    371         directory itself and its content will be copied. This
    372         behavior is similar to that of the program 'rsync'.
    373 
    374         Args:
    375                 source: either
    376                         1) a single file or directory, as a string
    377                         2) a list of one or more (possibly mixed)
    378                                 files or directories
    379                 dest: a file or a directory (if source contains a
    380                         directory or more than one element, you must
    381                         supply a directory dest)
    382                 delete_dest: if this is true, the command will also clear
    383                              out any old files at dest that are not in the
    384                              source
    385                 preserve_symlinks: controls if symlinks on the source will be
    386                     copied as such on the destination or transformed into the
    387                     referenced file/directory
    388 
    389         Raises:
    390                 AutoservRunError: the scp command failed
    391         """
    392         logging.debug('send_file. source: %s, dest: %s, delete_dest: %s,'
    393                       'preserve_symlinks:%s', source, dest,
    394                       delete_dest, preserve_symlinks)
    395         # Start a master SSH connection if necessary.
    396         self.start_master_ssh()
    397 
    398         if isinstance(source, basestring):
    399             source = [source]
    400         remote_dest = self._encode_remote_paths([dest])
    401 
    402         local_sources = [utils.sh_escape(path) for path in source]
    403         if not local_sources:
    404             raise error.TestError('source |%s| yielded an empty list' % (
    405                 source))
    406         if any([local_source.find('\x00') != -1 for
    407                 local_source in local_sources]):
    408             raise error.TestError('one or more sources include NUL char')
    409 
    410         # If rsync is disabled or fails, try scp.
    411         try_scp = True
    412         if self.use_rsync():
    413             logging.debug('Using Rsync.')
    414             try:
    415                 rsync = self._make_rsync_cmd(local_sources, remote_dest,
    416                                              delete_dest, preserve_symlinks)
    417                 utils.run(rsync)
    418                 try_scp = False
    419             except error.CmdError, e:
    420                 logging.warning("trying scp, rsync failed: %s", e)
    421 
    422         if try_scp:
    423             logging.debug('Trying scp.')
    424             # scp has no equivalent to --delete, just drop the entire dest dir
    425             if delete_dest:
    426                 is_dir = self.run("ls -d %s/" % dest,
    427                                   ignore_status=True).exit_status == 0
    428                 if is_dir:
    429                     cmd = "rm -rf %s && mkdir %s"
    430                     cmd %= (dest, dest)
    431                     self.run(cmd)
    432 
    433             local_sources = self._make_rsync_compatible_source(source, True)
    434             if local_sources:
    435                 scp = self._make_scp_cmd(local_sources, remote_dest)
    436                 try:
    437                     utils.run(scp)
    438                 except error.CmdError, e:
    439                     logging.debug('scp failed: %s', e)
    440                     raise error.AutoservRunError(e.args[0], e.args[1])
    441             else:
    442                 logging.debug('skipping scp for empty source list')
    443 
    444 
    445     def verify_ssh_user_access(self):
    446         """Verify ssh access to this host.
    447 
    448         @returns False if ssh_ping fails due to Permissions error, True
    449                  otherwise.
    450         """
    451         try:
    452             self.ssh_ping()
    453         except (error.AutoservSshPermissionDeniedError,
    454                 error.AutoservSshPingHostError):
    455             return False
    456         return True
    457 
    458 
    459     def ssh_ping(self, timeout=60, base_cmd='true'):
    460         """
    461         Pings remote host via ssh.
    462 
    463         @param timeout: Time in seconds before giving up.
    464                         Defaults to 60 seconds.
    465         @param base_cmd: The base command to run with the ssh ping.
    466                          Defaults to true.
    467         @raise AutoservSSHTimeout: If the ssh ping times out.
    468         @raise AutoservSshPermissionDeniedError: If ssh ping fails due to
    469                                                  permissions.
    470         @raise AutoservSshPingHostError: For other AutoservRunErrors.
    471         """
    472         try:
    473             self.run(base_cmd, timeout=timeout, connect_timeout=timeout)
    474         except error.AutoservSSHTimeout:
    475             msg = "Host (ssh) verify timed out (timeout = %d)" % timeout
    476             raise error.AutoservSSHTimeout(msg)
    477         except error.AutoservSshPermissionDeniedError:
    478             #let AutoservSshPermissionDeniedError be visible to the callers
    479             raise
    480         except error.AutoservRunError, e:
    481             # convert the generic AutoservRunError into something more
    482             # specific for this context
    483             raise error.AutoservSshPingHostError(e.description + '\n' +
    484                                                  repr(e.result_obj))
    485 
    486 
    487     def is_up(self, timeout=60, base_cmd='true'):
    488         """
    489         Check if the remote host is up by ssh-ing and running a base command.
    490 
    491         @param timeout: timeout in seconds.
    492         @param base_cmd: a base command to run with ssh. The default is 'true'.
    493         @returns True if the remote host is up before the timeout expires,
    494                  False otherwise.
    495         """
    496         try:
    497             self.ssh_ping(timeout=timeout, base_cmd=base_cmd)
    498         except error.AutoservError:
    499             return False
    500         else:
    501             return True
    502 
    503 
    504     def wait_up(self, timeout=None):
    505         """
    506         Wait until the remote host is up or the timeout expires.
    507 
    508         In fact, it will wait until an ssh connection to the remote
    509         host can be established, and getty is running.
    510 
    511         @param timeout time limit in seconds before returning even
    512             if the host is not up.
    513 
    514         @returns True if the host was found to be up before the timeout expires,
    515                  False otherwise
    516         """
    517         if timeout:
    518             current_time = int(time.time())
    519             end_time = current_time + timeout
    520 
    521         while not timeout or current_time < end_time:
    522             if self.is_up(timeout=end_time - current_time):
    523                 try:
    524                     if self.are_wait_up_processes_up():
    525                         logging.debug('Host %s is now up', self.hostname)
    526                         return True
    527                 except error.AutoservError:
    528                     pass
    529             time.sleep(1)
    530             current_time = int(time.time())
    531 
    532         logging.debug('Host %s is still down after waiting %d seconds',
    533                       self.hostname, int(timeout + time.time() - end_time))
    534         return False
    535 
    536 
    537     def wait_down(self, timeout=None, warning_timer=None, old_boot_id=None):
    538         """
    539         Wait until the remote host is down or the timeout expires.
    540 
    541         If old_boot_id is provided, this will wait until either the machine
    542         is unpingable or self.get_boot_id() returns a value different from
    543         old_boot_id. If the boot_id value has changed then the function
    544         returns true under the assumption that the machine has shut down
    545         and has now already come back up.
    546 
    547         If old_boot_id is None then until the machine becomes unreachable the
    548         method assumes the machine has not yet shut down.
    549 
    550         Based on this definition, the 4 possible permutations of timeout
    551         and old_boot_id are:
    552         1. timeout and old_boot_id: wait timeout seconds for either the
    553                                     host to become unpingable, or the boot id
    554                                     to change. In the latter case we've rebooted
    555                                     and in the former case we've only shutdown,
    556                                     but both cases return True.
    557         2. only timeout: wait timeout seconds for the host to become unpingable.
    558                          If the host remains pingable throughout timeout seconds
    559                          we return False.
    560         3. only old_boot_id: wait forever until either the host becomes
    561                              unpingable or the boot_id changes. Return true
    562                              when either of those conditions are met.
    563         4. not timeout, not old_boot_id: wait forever till the host becomes
    564                                          unpingable.
    565 
    566         @param timeout Time limit in seconds before returning even
    567             if the host is still up.
    568         @param warning_timer Time limit in seconds that will generate
    569             a warning if the host is not down yet.
    570         @param old_boot_id A string containing the result of self.get_boot_id()
    571             prior to the host being told to shut down. Can be None if this is
    572             not available.
    573 
    574         @returns True if the host was found to be down, False otherwise
    575         """
    576         #TODO: there is currently no way to distinguish between knowing
    577         #TODO: boot_id was unsupported and not knowing the boot_id.
    578         current_time = int(time.time())
    579         if timeout:
    580             end_time = current_time + timeout
    581 
    582         if warning_timer:
    583             warn_time = current_time + warning_timer
    584 
    585         if old_boot_id is not None:
    586             logging.debug('Host %s pre-shutdown boot_id is %s',
    587                           self.hostname, old_boot_id)
    588 
    589         # Impose semi real-time deadline constraints, since some clients
    590         # (eg: watchdog timer tests) expect strict checking of time elapsed.
    591         # Each iteration of this loop is treated as though it atomically
    592         # completes within current_time, this is needed because if we used
    593         # inline time.time() calls instead then the following could happen:
    594         #
    595         # while not timeout or time.time() < end_time:      [23 < 30]
    596         #    some code.                                     [takes 10 secs]
    597         #    try:
    598         #        new_boot_id = self.get_boot_id(timeout=end_time - time.time())
    599         #                                                   [30 - 33]
    600         # The last step will lead to a return True, when in fact the machine
    601         # went down at 32 seconds (>30). Hence we need to pass get_boot_id
    602         # the same time that allowed us into that iteration of the loop.
    603         while not timeout or current_time < end_time:
    604             try:
    605                 new_boot_id = self.get_boot_id(timeout=end_time-current_time)
    606             except error.AutoservError:
    607                 logging.debug('Host %s is now unreachable over ssh, is down',
    608                               self.hostname)
    609                 return True
    610             else:
    611                 # if the machine is up but the boot_id value has changed from
    612                 # old boot id, then we can assume the machine has gone down
    613                 # and then already come back up
    614                 if old_boot_id is not None and old_boot_id != new_boot_id:
    615                     logging.debug('Host %s now has boot_id %s and so must '
    616                                   'have rebooted', self.hostname, new_boot_id)
    617                     return True
    618 
    619             if warning_timer and current_time > warn_time:
    620                 self.record("INFO", None, "shutdown",
    621                             "Shutdown took longer than %ds" % warning_timer)
    622                 # Print the warning only once.
    623                 warning_timer = None
    624                 # If a machine is stuck switching runlevels
    625                 # This may cause the machine to reboot.
    626                 self.run('kill -HUP 1', ignore_status=True)
    627 
    628             time.sleep(1)
    629             current_time = int(time.time())
    630 
    631         return False
    632 
    633 
    634     # tunable constants for the verify & repair code
    635     AUTOTEST_GB_DISKSPACE_REQUIRED = get_value("SERVER",
    636                                                "gb_diskspace_required",
    637                                                type=float,
    638                                                default=20.0)
    639 
    640 
    641     def verify_connectivity(self):
    642         super(AbstractSSHHost, self).verify_connectivity()
    643 
    644         logging.info('Pinging host ' + self.hostname)
    645         self.ssh_ping()
    646         logging.info("Host (ssh) %s is alive", self.hostname)
    647 
    648         if self.is_shutting_down():
    649             raise error.AutoservHostIsShuttingDownError("Host is shutting down")
    650 
    651 
    652     def verify_software(self):
    653         super(AbstractSSHHost, self).verify_software()
    654         try:
    655             self.check_diskspace(autotest.Autotest.get_install_dir(self),
    656                                  self.AUTOTEST_GB_DISKSPACE_REQUIRED)
    657         except error.AutoservHostError:
    658             raise           # only want to raise if it's a space issue
    659         except autotest.AutodirNotFoundError:
    660             # autotest dir may not exist, etc. ignore
    661             logging.debug('autodir space check exception, this is probably '
    662                           'safe to ignore\n' + traceback.format_exc())
    663 
    664 
    665     def close(self):
    666         super(AbstractSSHHost, self).close()
    667         self._cleanup_master_ssh()
    668         os.remove(self.known_hosts_file)
    669         self.rpc_server_tracker.disconnect_all()
    670 
    671 
    672     def _cleanup_master_ssh(self):
    673         """
    674         Release all resources (process, temporary directory) used by an active
    675         master SSH connection.
    676         """
    677         # If a master SSH connection is running, kill it.
    678         if self.master_ssh_job is not None:
    679             logging.debug('Nuking master_ssh_job.')
    680             utils.nuke_subprocess(self.master_ssh_job.sp)
    681             self.master_ssh_job = None
    682 
    683         # Remove the temporary directory for the master SSH socket.
    684         if self.master_ssh_tempdir is not None:
    685             logging.debug('Cleaning master_ssh_tempdir.')
    686             self.master_ssh_tempdir.clean()
    687             self.master_ssh_tempdir = None
    688             self.master_ssh_option = ''
    689 
    690 
    691     def start_master_ssh(self, timeout=5):
    692         """
    693         Called whenever a slave SSH connection needs to be initiated (e.g., by
    694         run, rsync, scp). If master SSH support is enabled and a master SSH
    695         connection is not active already, start a new one in the background.
    696         Also, cleanup any zombie master SSH connections (e.g., dead due to
    697         reboot).
    698 
    699         timeout: timeout in seconds (default 5) to wait for master ssh
    700                  connection to be established. If timeout is reached, a
    701                  warning message is logged, but no other action is taken.
    702         """
    703         if not enable_master_ssh:
    704             return
    705 
    706         # Multiple processes might try in parallel to clean up the old master
    707         # ssh connection and create a new one, therefore use a lock to protect
    708         # against race conditions.
    709         with self._lock:
    710             # If a previously started master SSH connection is not running
    711             # anymore, it needs to be cleaned up and then restarted.
    712             if self.master_ssh_job is not None:
    713                 socket_path = os.path.join(self.master_ssh_tempdir.name,
    714                                            'socket')
    715                 if (not os.path.exists(socket_path) or
    716                         self.master_ssh_job.sp.poll() is not None):
    717                     logging.info("Master ssh connection to %s is down.",
    718                                  self.hostname)
    719                     self._cleanup_master_ssh()
    720 
    721             # Start a new master SSH connection.
    722             if self.master_ssh_job is None:
    723                 # Create a shared socket in a temp location.
    724                 self.master_ssh_tempdir = autotemp.tempdir(
    725                         unique_id='ssh-master')
    726                 self.master_ssh_option = ("-o ControlPath=%s/socket" %
    727                                           self.master_ssh_tempdir.name)
    728 
    729                 # Start the master SSH connection in the background.
    730                 master_cmd = self.ssh_command(
    731                         options="-N -o ControlMaster=yes")
    732                 logging.info("Starting master ssh connection '%s'", master_cmd)
    733                 self.master_ssh_job = utils.BgJob(master_cmd,
    734                                                   nickname='master-ssh',
    735                                                   no_pipes=True)
    736                 # To prevent a race between the the master ssh connection
    737                 # startup and its first attempted use, wait for socket file to
    738                 # exist before returning.
    739                 end_time = time.time() + timeout
    740                 socket_file_path = os.path.join(self.master_ssh_tempdir.name,
    741                                                 'socket')
    742                 while time.time() < end_time:
    743                     if os.path.exists(socket_file_path):
    744                         break
    745                     time.sleep(.2)
    746                 else:
    747                     logging.info('Timed out waiting for master-ssh connection '
    748                                  'to be established.')
    749 
    750 
    751     def clear_known_hosts(self):
    752         """Clears out the temporary ssh known_hosts file.
    753 
    754         This is useful if the test SSHes to the machine, then reinstalls it,
    755         then SSHes to it again.  It can be called after the reinstall to
    756         reduce the spam in the logs.
    757         """
    758         logging.info("Clearing known hosts for host '%s', file '%s'.",
    759                      self.hostname, self.known_hosts_file)
    760         # Clear out the file by opening it for writing and then closing.
    761         fh = open(self.known_hosts_file, "w")
    762         fh.close()
    763 
    764 
    765     def collect_logs(self, remote_src_dir, local_dest_dir, ignore_errors=True):
    766         """Copy log directories from a host to a local directory.
    767 
    768         @param remote_src_dir: A destination directory on the host.
    769         @param local_dest_dir: A path to a local destination directory.
    770             If it doesn't exist it will be created.
    771         @param ignore_errors: If True, ignore exceptions.
    772 
    773         @raises OSError: If there were problems creating the local_dest_dir and
    774             ignore_errors is False.
    775         @raises AutoservRunError, AutotestRunError: If something goes wrong
    776             while copying the directories and ignore_errors is False.
    777         """
    778         locally_created_dest = False
    779         if (not os.path.exists(local_dest_dir)
    780                 or not os.path.isdir(local_dest_dir)):
    781             try:
    782                 os.makedirs(local_dest_dir)
    783                 locally_created_dest = True
    784             except OSError as e:
    785                 logging.warning('Unable to collect logs from host '
    786                                 '%s: %s', self.hostname, e)
    787                 if not ignore_errors:
    788                     raise
    789                 return
    790         try:
    791             self.get_file(
    792                     remote_src_dir, local_dest_dir, preserve_symlinks=True)
    793         except (error.AutotestRunError, error.AutoservRunError,
    794                 error.AutoservSSHTimeout) as e:
    795             logging.warning('Collection of %s to local dir %s from host %s '
    796                             'failed: %s', remote_src_dir, local_dest_dir,
    797                             self.hostname, e)
    798             if locally_created_dest:
    799                 shutil.rmtree(local_dest_dir, ignore_errors=ignore_errors)
    800             if not ignore_errors:
    801                 raise
    802 
    803 
    804     def _create_ssh_tunnel(self, port, local_port):
    805         """Create an ssh tunnel from local_port to port.
    806 
    807         @param port: remote port on the host.
    808         @param local_port: local forwarding port.
    809 
    810         @return: the tunnel process.
    811         """
    812         tunnel_options = '-n -N -q -L %d:localhost:%d' % (local_port, port)
    813         ssh_cmd = self.make_ssh_command(opts=tunnel_options)
    814         tunnel_cmd = '%s %s' % (ssh_cmd, self.hostname)
    815         logging.debug('Full tunnel command: %s', tunnel_cmd)
    816         tunnel_proc = subprocess.Popen(tunnel_cmd, shell=True, close_fds=True)
    817         logging.debug('Started ssh tunnel, local = %d'
    818                       ' remote = %d, pid = %d',
    819                       local_port, port, tunnel_proc.pid)
    820         return tunnel_proc
    821 
    822 
    823     def rpc_port_forward(self, port, local_port):
    824         """
    825         Forwards a port securely through a tunnel process from the server
    826         to the DUT for RPC server connection.
    827 
    828         @param port: remote port on the DUT.
    829         @param local_port: local forwarding port.
    830 
    831         @return: the tunnel process.
    832         """
    833         return self._create_ssh_tunnel(port, local_port)
    834 
    835 
    836     def rpc_port_disconnect(self, tunnel_proc, port):
    837         """
    838         Disconnects a previously forwarded port from the server to the DUT for
    839         RPC server connection.
    840 
    841         @param tunnel_proc: the original tunnel process returned from
    842                             |rpc_port_forward|.
    843         @param port: remote port on the DUT.
    844 
    845         """
    846         if tunnel_proc.poll() is None:
    847             tunnel_proc.terminate()
    848             logging.debug('Terminated tunnel, pid %d', tunnel_proc.pid)
    849         else:
    850             logging.debug('Tunnel pid %d terminated early, status %d',
    851                           tunnel_proc.pid, tunnel_proc.returncode)
    852 
    853 
    854     def get_os_type(self):
    855         """Returns the host OS descriptor (to be implemented in subclasses).
    856 
    857         @return A string describing the OS type.
    858         """
    859         raise NotImplementedError