gsh/remote_dispatcher.py

   1 # This program is free software; you can redistribute it and/or modify
   2 # it under the terms of the GNU General Public License as published by
   3 # the Free Software Foundation; either version 2 of the License, or
   4 # (at your option) any later version.
   5 #
   6 # This program is distributed in the hope that it will be useful,
   7 # but WITHOUT ANY WARRANTY; without even the implied warranty of
   8 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   9 # GNU Library General Public License for more details.
  10 #
  11 # You should have received a copy of the GNU General Public License
  12 # along with this program; if not, write to the Free Software
  13 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  14 #
  15 # See the COPYING file for license information.
  16 #
  17 # Copyright (c) 2006, 2007, 2008 Guillaume Chazarain <guichaz@gmail.com>
  18
  19 import asyncore
  20 import os
  21 import pty
  22 import random
  23 import signal
  24 import sys
  25 import termios
  26
  27 from gsh.buffered_dispatcher import buffered_dispatcher
  28 from gsh.console import console_output
  29 from gsh import file_transfer
  30
  31 # Either the remote shell is expecting a command or one is already running
  32 STATE_NAMES = ['not_started', 'idle', 'running', 'terminated']
  33
  34 STATE_NOT_STARTED,         \
  35 STATE_IDLE,                \
  36 STATE_RUNNING,             \
  37 STATE_TERMINATED = range(len(STATE_NAMES))
  38
  39 # Count the total number of remote_dispatcher.handle_read() invocations
  40 nr_handle_read = 0
  41
  42 def main_loop_iteration(timeout=None):
  43     """Return the number of remote_dispatcher.handle_read() calls made by this
  44     iteration"""
  45     prev_nr_read = nr_handle_read
  46     asyncore.loop(count=1, timeout=timeout, use_poll=True)
  47     return nr_handle_read - prev_nr_read
  48
  49 def log(msg):
  50     if options.log_file:
  51         options.log_file.write(msg)
  52
  53 class remote_dispatcher(buffered_dispatcher):
  54     """A remote_dispatcher is a ssh process we communicate with"""
  55
  56     def __init__(self, hostname):
  57         self.pid, fd = pty.fork()
  58         if self.pid == 0:
  59             # Child
  60             self.launch_ssh(hostname)
  61             sys.exit(1)
  62
  63         # Parent
  64         buffered_dispatcher.__init__(self, fd)
  65         self.hostname = hostname
  66         self.debug = options.debug
  67         self.active = True # deactived shells are dead forever
  68         self.enabled = True # shells can be enabled and disabled
  69         self.state = STATE_NOT_STARTED
  70         self.termination = None
  71         self.term_size = (-1, -1)
  72         self.display_name = ''
  73         self.change_name(hostname)
  74         self.init_string = self.configure_tty() + self.set_prompt()
  75         self.init_string_sent = False
  76         self.pending_rename = None
  77         self.file_transfer_cookie = None
  78         self.command = options.command
  79
  80     def launch_ssh(self, name):
  81         """Launch the ssh command in the child process"""
  82         evaluated = options.ssh % {'host': name}
  83         if evaluated == options.ssh:
  84             evaluated = '%s %s' % (evaluated, name)
  85         os.execlp('/bin/sh', 'sh', '-c', evaluated)
  86
  87     def set_enabled(self, enabled):
  88         from gsh.dispatchers import update_max_display_name_length
  89         self.enabled = enabled
  90         if options.interactive:
  91             # In non-interactive mode, remote processes leave as soon
  92             # as they are terminated, but we don't want to break the
  93             # indentation if all the remaining processes have short names.
  94             l = len(self.display_name)
  95             if not enabled:
  96                 l = -l
  97             update_max_display_name_length(l)
  98
  99     def change_state(self, state):
 100         """Change the state of the remote process, logging the change"""
 101         if state is not self.state:
 102             if self.debug:
 103                 self.print_debug('state => %s' % (STATE_NAMES[state]))
 104             self.state = state
 105
 106     def disconnect(self):
 107         """We are no more interested in this remote process"""
 108         try:
 109             os.kill(self.pid, signal.SIGKILL)
 110         except OSError:
 111             # The process was already dead, no problem
 112             pass
 113         self.read_buffer = ''
 114         self.write_buffer = ''
 115         self.active = False
 116         self.set_enabled(False)
 117         if options.abort_error and self.state is STATE_NOT_STARTED:
 118             raise asyncore.ExitNow(1)
 119
 120     def reconnect(self):
 121         """Relaunch and reconnect to this same remote process"""
 122         self.disconnect()
 123         self.close()
 124         remote_dispatcher(self.hostname)
 125
 126     def dispatch_termination(self):
 127         """Start the termination procedure on this remote process, using the
 128         same trick as the prompt to hide it"""
 129         if not self.termination:
 130             self.term1 = '[gsh termination ' + str(random.random())[2:]
 131             self.term2 = str(random.random())[2:] + ']'
 132             self.termination = self.term1 + self.term2
 133             self.dispatch_command('/bin/echo "%s""%s"\n' %
 134                                                        (self.term1, self.term2))
 135             if self.state is not STATE_NOT_STARTED:
 136                 self.change_state(STATE_RUNNING)
 137
 138     def configure_tty(self):
 139         """We don't want \n to be replaced with \r\n, and we disable the echo"""
 140         attr = termios.tcgetattr(self.fd)
 141         attr[1] &= ~termios.ONLCR # oflag
 142         attr[3] &= ~termios.ECHO # lflag
 143         termios.tcsetattr(self.fd, termios.TCSANOW, attr)
 144         # unsetopt zle prevents Zsh from resetting the tty
 145         return 'unsetopt zle 2> /dev/null;stty -echo -onlcr;'
 146
 147     def set_prompt(self):
 148         """The prompt is important because we detect the readyness of a process
 149         by waiting for its prompt. The prompt is built in two parts for it not
 150         to appear in its building"""
 151         # No right prompt
 152         command_line = 'RPS1=;RPROMPT=;'
 153         command_line += 'TERM=ansi;'
 154         prompt1 = '[gsh prompt ' + str(random.random())[2:]
 155         prompt2 = str(random.random())[2:] + ']'
 156         self.prompt = prompt1 + prompt2
 157         command_line += 'PS1="%s""%s\n"\n' % (prompt1, prompt2)
 158         return command_line
 159
 160     def readable(self):
 161         """We are always interested in reading from active remote processes if
 162         the buffer is OK"""
 163         return self.active and buffered_dispatcher.readable(self)
 164
 165     def handle_error(self):
 166         """An exception may or may not lead to a disconnection"""
 167         if buffered_dispatcher.handle_error(self):
 168             console_output('Error talking to %s\n' % self.display_name)
 169             self.disconnect()
 170
 171     def print_lines(self, lines):
 172         from gsh.dispatchers import max_display_name_length
 173         lines = lines.strip('\n')
 174         while True:
 175             no_empty_lines = lines.replace('\n\n', '\n')
 176             if len(no_empty_lines) == len(lines):
 177                 break
 178             lines = no_empty_lines
 179         if not lines:
 180             return
 181         indent = max_display_name_length - len(self.display_name)
 182         prefix = self.display_name + indent * ' ' + ': '
 183         console_output(prefix + lines.replace('\n', '\n' + prefix) + '\n')
 184
 185     def handle_read_fast_case(self, data):
 186         """If we are in a fast case we'll avoid the long processing of each
 187         line"""
 188         if self.prompt in data or self.state is not STATE_RUNNING or \
 189            self.termination and (self.term1 in data or self.term2 in data) or \
 190            self.pending_rename and self.pending_rename in data or \
 191            self.file_transfer_cookie and self.file_transfer_cookie in data:
 192             # Slow case :-(
 193             return False
 194
 195         last_nl = data.rfind('\n')
 196         if last_nl == -1:
 197             # No '\n' in data => slow case
 198             return False
 199         self.read_buffer = data[last_nl + 1:]
 200         self.print_lines(data[:last_nl])
 201         return True
 202
 203     def handle_read(self):
 204         """We got some output from a remote shell, this is one of the state
 205         machine"""
 206         if not self.active:
 207             return
 208         global nr_handle_read
 209         nr_handle_read += 1
 210         new_data = buffered_dispatcher.handle_read(self)
 211         if self.debug:
 212             self.print_debug('==> ' + new_data)
 213         if self.handle_read_fast_case(self.read_buffer):
 214             return
 215         lf_pos = new_data.find('\n')
 216         if lf_pos >= 0:
 217             # Optimization: we knew there were no '\n' in the previous read
 218             # buffer, so we searched only in the new_data and we offset the
 219             # found index by the length of the previous buffer
 220             lf_pos += len(self.read_buffer) - len(new_data)
 221         while lf_pos >= 0:
 222             # For each line in the buffer
 223             line = self.read_buffer[:lf_pos + 1]
 224             if self.prompt in line:
 225                 if options.interactive:
 226                     self.change_state(STATE_IDLE)
 227                 elif self.command:
 228                     self.dispatch_command(self.command + '\n')
 229                     self.command = None
 230                 else:
 231                     self.dispatch_termination()
 232             elif self.termination and self.termination in line:
 233                 self.change_state(STATE_TERMINATED)
 234                 self.disconnect()
 235             elif self.termination and self.term1 in line and self.term2 in line:
 236                 # Just ignore this line
 237                 pass
 238             elif self.pending_rename and self.pending_rename in line:
 239                 self.received_rename(line)
 240             elif self.file_transfer_cookie and self.file_transfer_cookie in line:
 241                 file_transfer.received_cookie(self, line)
 242             elif self.state in (STATE_IDLE, STATE_RUNNING):
 243                 self.print_lines(line)
 244             elif self.state is STATE_NOT_STARTED:
 245                 if 'The authenticity of host' in line:
 246                     msg = line.strip('\n')
 247                 elif 'REMOTE HOST IDENTIFICATION HAS CHANGED' in line:
 248                     msg = 'Remote host identification has changed.'
 249                 else:
 250                     msg = None
 251
 252                 if msg:
 253                     self.print_lines(msg + ' Closing connection, consider ' +
 254                                      'manually connecting or using ' +
 255                                      'ssh-keyscan.')
 256                     self.disconnect()
 257
 258             # Go to the next line in the buffer
 259             self.read_buffer = self.read_buffer[lf_pos + 1:]
 260             if self.handle_read_fast_case(self.read_buffer):
 261                 return
 262             lf_pos = self.read_buffer.find('\n')
 263         if self.state is STATE_NOT_STARTED and not self.init_string_sent:
 264             self.dispatch_write(self.init_string)
 265             self.init_string_sent = True
 266
 267     def print_unfinished_line(self):
 268         """The unfinished line stayed long enough in the buffer to be printed"""
 269         if self.state is STATE_RUNNING:
 270             self.print_lines(self.read_buffer)
 271             self.read_buffer = ''
 272
 273     def writable(self):
 274         """Do we want to write something?"""
 275         return self.active and buffered_dispatcher.writable(self)
 276
 277     def handle_write(self):
 278         """Let's write as much as we can"""
 279         num_sent = self.send(self.write_buffer)
 280         if self.debug:
 281             self.print_debug('<== ' + self.write_buffer[:num_sent])
 282         self.write_buffer = self.write_buffer[num_sent:]
 283
 284     def print_debug(self, msg):
 285         """Log some debugging information to the console"""
 286         state = STATE_NAMES[self.state]
 287         msg = msg.encode('string_escape')
 288         console_output('[dbg] %s[%s]: %s\n' % (self.display_name, state, msg))
 289
 290     def get_info(self):
 291         """Return a list with all information available about this process"""
 292         if self.active:
 293             state = STATE_NAMES[self.state]
 294         else:
 295             state = ''
 296
 297         if self.debug:
 298             debug = 'debug'
 299         else:
 300             debug = ''
 301
 302         return [self.display_name, 'fd:%d' % (self.fd),
 303                 'r:%d' % (len(self.read_buffer)),
 304                 'w:%d' % (len(self.write_buffer)),
 305                 self.active and 'active' or 'dead',
 306                 self.enabled and 'enabled' or 'disabled',
 307                 state,
 308                 debug]
 309
 310     def dispatch_write(self, buf):
 311         """There is new stuff to write when possible"""
 312         if self.active and self.enabled:
 313             buffered_dispatcher.dispatch_write(self, buf)
 314             return True
 315
 316     def dispatch_command(self, command):
 317         if self.dispatch_write(command):
 318             self.change_state(STATE_RUNNING)
 319
 320     def change_name(self, name):
 321         """Change the name of the shell, possibly updating the maximum name
 322         length"""
 323         from gsh import dispatchers
 324         if not name:
 325             name = self.hostname
 326         previous_name_len = len(self.display_name)
 327         self.display_name = None
 328         self.display_name = dispatchers.make_unique_name(name)
 329         dispatchers.update_max_display_name_length(len(self.display_name))
 330         dispatchers.update_max_display_name_length(-previous_name_len)
 331
 332     def rename(self, string):
 333         """Send to the remote shell, its new name to be shell expanded"""
 334         if string:
 335             pending_rename1 = str(random.random())[2:] + ','
 336             pending_rename2 = str(random.random())[2:] + ':'
 337             self.pending_rename = pending_rename1 + pending_rename2
 338             self.dispatch_command('/bin/echo "%s""%s" %s\n' %
 339                                     (pending_rename1, pending_rename2, string))
 340         else:
 341             self.change_name(self.hostname)
 342
 343     def received_rename(self, line):
 344         """The shell expanded name has been received"""
 345         new_name = line[len(self.pending_rename) + 1:-1]
 346         self.change_name(new_name)
 347         self.pending_rename = None
 348
 349     def __str__(self):
 350         return self.display_name