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mirror of https://github.com/GNS3/gns3-server synced 2024-12-11 09:38:08 +00:00
gns3-server/gns3server/compute/iou/ioucon.py
2016-06-14 09:50:07 +02:00

677 lines
21 KiB
Python

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#
# Copyright (C) 2013, 2014 James E. Carpenter
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
import socket
import sys
import os
import select
try:
import fcntl
import termios
import tty
except ImportError:
# On windows it's not available but this module can be included by the test suite
pass
import struct
import time
import argparse
import traceback
import logging
log = logging.getLogger(__name__)
# Escape characters
ESC_CHAR = '^^' # can be overriden from command line
ESC_QUIT = 'q'
# IOU seems to only send *1* byte at a time. If
# they ever fix that we'll be ready for it.
BUFFER_SIZE = 1024
# How long to wait before retrying a connection (seconds)
RETRY_DELAY = 3
# How often to test an idle connection (seconds)
POLL_TIMEOUT = 3
EXIT_SUCCESS = 0
EXIT_FAILURE = 1
EXIT_ABORT = 2
# Mostly from:
# https://code.google.com/p/miniboa/source/browse/trunk/miniboa/telnet.py
# --[ Telnet Commands ]---------------------------------------------------------
SE = 240 # End of sub-negotiation parameters
NOP = 241 # No operation
DATMK = 242 # Data stream portion of a sync.
BREAK = 243 # NVT Character BRK
IP = 244 # Interrupt Process
AO = 245 # Abort Output
AYT = 246 # Are you there
EC = 247 # Erase Character
EL = 248 # Erase Line
GA = 249 # The Go Ahead Signal
SB = 250 # Sub-option to follow
WILL = 251 # Will; request or confirm option begin
WONT = 252 # Wont; deny option request
DO = 253 # Do = Request or confirm remote option
DONT = 254 # Don't = Demand or confirm option halt
IAC = 255 # Interpret as Command
SEND = 1 # Sub-process negotiation SEND command
IS = 0 # Sub-process negotiation IS command
# --[ Telnet Options ]----------------------------------------------------------
BINARY = 0 # Transmit Binary
ECHO = 1 # Echo characters back to sender
RECON = 2 # Reconnection
SGA = 3 # Suppress Go-Ahead
TMARK = 6 # Timing Mark
TTYPE = 24 # Terminal Type
NAWS = 31 # Negotiate About Window Size
LINEMO = 34 # Line Mode
class FileLock:
# struct flock { /* from fcntl(2) */
# ...
# short l_type; /* Type of lock: F_RDLCK,
# F_WRLCK, F_UNLCK */
# short l_whence; /* How to interpret l_start:
# SEEK_SET, SEEK_CUR, SEEK_END */
# off_t l_start; /* Starting offset for lock */
# off_t l_len; /* Number of bytes to lock */
# pid_t l_pid; /* PID of process blocking our lock
# (F_GETLK only) */
# ...
# };
_flock = struct.Struct('hhqql')
def __init__(self, fname=None):
self.fd = None
self.fname = fname
def get_lock(self):
flk = self._flock.pack(fcntl.F_WRLCK, os.SEEK_SET,
0, 0, os.getpid())
flk = self._flock.unpack(
fcntl.fcntl(self.fd, fcntl.F_GETLK, flk))
# If it's not locked (or is locked by us) then return None,
# otherwise return the PID of the owner.
if flk[0] == fcntl.F_UNLCK:
return None
return flk[4]
def lock(self):
try:
self.fd = open('{}.lck'.format(self.fname), 'a')
except Exception as e:
raise LockError("Couldn't get lock on {}: {}"
.format(self.fname, e))
flk = self._flock.pack(fcntl.F_WRLCK, os.SEEK_SET, 0, 0, 0)
try:
fcntl.fcntl(self.fd, fcntl.F_SETLK, flk)
except BlockingIOError:
raise LockError("Already connected. PID {} has lock on {}"
.format(self.get_lock(), self.fname))
# If we got here then we must have the lock. Store the PID.
self.fd.truncate(0)
self.fd.write('{}\n'.format(os.getpid()))
self.fd.flush()
def unlock(self):
if self.fd:
# Deleting first prevents a race condition
try:
os.unlink(self.fd.name)
except FileNotFoundError as e:
log.debug("{}".format(e))
self.fd.close()
def __enter__(self):
self.lock()
def __exit__(self, exc_type, exc_val, exc_tb):
self.unlock()
return False
class Console:
def fileno(self):
raise NotImplementedError("Only routers have fileno()")
class TTY(Console):
def read(self, fileno, bufsize):
return self.fd.read(bufsize)
def write(self, buf):
return self.fd.write(buf)
def register(self, epoll):
self.epoll = epoll
epoll.register(self.fd, select.EPOLLIN | select.EPOLLET)
def unregister(self, epoll):
epoll.unregister(self.fd)
def __enter__(self):
try:
self.fd = open('/dev/tty', 'r+b', buffering=0)
except OSError as e:
raise TTYError("Couldn't open controlling TTY: {}".format(e))
# Save original flags
self.termios = termios.tcgetattr(self.fd)
self.fcntl = fcntl.fcntl(self.fd, fcntl.F_GETFL)
# Update flags
tty.setraw(self.fd, termios.TCSANOW)
fcntl.fcntl(self.fd, fcntl.F_SETFL, self.fcntl | os.O_NONBLOCK)
return self
def __exit__(self, exc_type, exc_val, exc_tb):
# Restore flags to original settings
termios.tcsetattr(self.fd, termios.TCSANOW, self.termios)
fcntl.fcntl(self.fd, fcntl.F_SETFL, self.fcntl)
self.fd.close()
return False
class TelnetServer(Console):
def __init__(self, addr, port, stop_event):
self.addr = addr
self.port = port
self.fd_dict = {}
self.stop_event = stop_event
def read(self, fileno, bufsize):
# Someone wants to connect?
if fileno == self.sock_fd.fileno():
self._accept()
return None
self._cur_fileno = fileno
# Read a maximum of _bufsize_ bytes without blocking. When it
# would want to block it means there's no more data. An empty
# buffer normally means that we've been disconnected.
try:
buf = self._read_cur(bufsize, socket.MSG_DONTWAIT)
except BlockingIOError:
return None
except ConnectionResetError:
buf = b''
if not buf:
self._disconnect(fileno)
# Process and remove any telnet commands from the buffer
if IAC in buf:
buf = self._IAC_parser(buf)
return buf
def write(self, buf):
for fd in self.fd_dict.values():
fd.send(buf)
def register(self, epoll):
self.epoll = epoll
epoll.register(self.sock_fd, select.EPOLLIN)
def unregister(self, epoll):
epoll.unregister(self.sock_fd)
def _read_block(self, bufsize):
buf = self._read_cur(bufsize, socket.MSG_WAITALL)
# If we don't get everything we were looking for then the
# client probably disconnected.
if len(buf) < bufsize:
self._disconnect(self._cur_fileno)
return buf
def _read_cur(self, bufsize, flags):
return self.fd_dict[self._cur_fileno].recv(bufsize, flags)
def _write_cur(self, buf):
return self.fd_dict[self._cur_fileno].send(buf)
def _IAC_parser(self, buf):
skip_to = 0
while not self.stop_event.is_set():
# Locate an IAC to process
iac_loc = buf.find(IAC, skip_to)
if iac_loc < 0:
break
# Get the TELNET command
iac_cmd = bytearray([IAC])
try:
iac_cmd.append(buf[iac_loc + 1])
except IndexError:
buf.extend(self._read_block(1))
iac_cmd.append(buf[iac_loc + 1])
# Is this just a 2-byte TELNET command?
if iac_cmd[1] not in [WILL, WONT, DO, DONT]:
if iac_cmd[1] == AYT:
log.debug("Telnet server received Are-You-There (AYT)")
self._write_cur(
b'\r\nYour Are-You-There received. I am here.\r\n'
)
elif iac_cmd[1] == IAC:
# It's data, not an IAC
iac_cmd.pop()
# This prevents the 0xff from being
# interputed as yet another IAC
skip_to = iac_loc + 1
log.debug("Received IAC IAC")
elif iac_cmd[1] == NOP:
pass
else:
log.debug("Unhandled telnet command: "
"{0:#x} {1:#x}".format(*iac_cmd))
# This must be a 3-byte TELNET command
else:
try:
iac_cmd.append(buf[iac_loc + 2])
except IndexError:
buf.extend(self._read_block(1))
iac_cmd.append(buf[iac_loc + 2])
# We do ECHO, SGA, and BINARY. Period.
if iac_cmd[1] == DO:
if iac_cmd[2] not in [ECHO, SGA, BINARY]:
self._write_cur(bytes([IAC, WONT, iac_cmd[2]]))
log.debug("Telnet WON'T {:#x}".format(iac_cmd[2]))
elif iac_cmd[1] == WILL and iac_cmd[2] == BINARY:
pass # It's standard negociation we can ignore it
else:
log.debug("Unhandled telnet command: "
"{0:#x} {1:#x} {2:#x}".format(*iac_cmd))
# Remove the entire TELNET command from the buffer
buf = buf.replace(iac_cmd, b'', 1)
# Return the new copy of the buffer, minus telnet commands
return buf
def _accept(self):
fd, addr = self.sock_fd.accept()
self.fd_dict[fd.fileno()] = fd
self.epoll.register(fd, select.EPOLLIN | select.EPOLLET)
log.info("Telnet connection from {}:{}".format(addr[0], addr[1]))
# This is a one-way negotiation. This is very basic so there
# shouldn't be any problems with any decent client.
fd.send(bytes([IAC, WILL, ECHO,
IAC, WILL, SGA,
IAC, WILL, BINARY,
IAC, DO, BINARY]))
if args.telnet_limit and len(self.fd_dict) > args.telnet_limit:
fd.send(b'\r\nToo many connections\r\n')
self._disconnect(fd.fileno())
log.warn("Client disconnected because of too many connections. "
"(limit currently {})".format(args.telnet_limit))
def _disconnect(self, fileno):
fd = self.fd_dict.pop(fileno)
log.info("Telnet client disconnected")
try:
fd.shutdown(socket.SHUT_RDWR)
except OSError as e:
log.warn("shutdown: {}".format(e))
fd.close()
def __enter__(self):
# Open a socket and start listening
info = socket.getaddrinfo(self.addr, self.port, socket.AF_UNSPEC, socket.SOCK_STREAM, 0, socket.AI_PASSIVE)
if not info:
raise TelnetServerError("getaddrinfo returns an empty list on {}:{}".format(self.addr, self.port))
for res in info:
af, socktype, proto, _, sa = res
sock_fd = socket.socket(af, socktype, proto)
sock_fd.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
try:
sock_fd.bind(sa)
except OSError:
raise TelnetServerError("Cannot bind to {}:{}"
.format(self.addr, self.port))
sock_fd.listen(socket.SOMAXCONN)
self.sock_fd = sock_fd
log.info("Telnet server ready for connections on {}:{}".format(self.addr, self.port))
return self
def __exit__(self, exc_type, exc_val, exc_tb):
for fileno in list(self.fd_dict.keys()):
self._disconnect(fileno)
self.sock_fd.close()
return False
class IOU:
def __init__(self, ttyC, ttyS, stop_event):
self.ttyC = ttyC
self.ttyS = ttyS
self.stop_event = stop_event
def read(self, bufsize):
try:
buf = self.fd.recv(bufsize)
except BlockingIOError:
return None
return buf
def write(self, buf):
try:
self.fd.send(buf)
except BlockingIOError:
return
def _open(self):
self.fd = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
self.fd.setblocking(False)
def _bind(self):
try:
os.unlink(self.ttyC)
except FileNotFoundError:
pass
except Exception as e:
raise NetioError("Couldn't unlink socket {}: {}".format(self.ttyC, e))
try:
self.fd.bind(self.ttyC)
except Exception as e:
raise NetioError("Couldn't create socket {}: {}".format(self.ttyC, e))
def _connect(self):
# Keep trying until we connect or die trying
while not self.stop_event.is_set():
try:
self.fd.connect(self.ttyS)
except FileNotFoundError:
log.debug("Waiting to connect to {}".format(self.ttyS))
time.sleep(RETRY_DELAY)
except Exception as e:
raise NetioError("Couldn't connect to socket {}: {}".format(self.ttyS, e))
else:
break
def register(self, epoll):
self.epoll = epoll
epoll.register(self.fd, select.EPOLLIN | select.EPOLLET)
def unregister(self, epoll):
epoll.unregister(self.fd)
def fileno(self):
return self.fd.fileno()
def __enter__(self):
self._open()
self._bind()
self._connect()
return self
def __exit__(self, exc_type, exc_val, exc_tb):
os.unlink(self.ttyC)
self.fd.close()
return False
class IOUConError(Exception):
pass
class LockError(IOUConError):
pass
class NetioError(IOUConError):
pass
class TTYError(IOUConError):
pass
class TelnetServerError(IOUConError):
pass
class ConfigError(IOUConError):
pass
def mkdir_netio(netio_dir):
try:
os.mkdir(netio_dir)
except FileExistsError:
pass
except Exception as e:
raise NetioError("Couldn't create directory {}: {}".format(netio_dir, e))
def send_recv_loop(epoll, console, router, esc_char, stop_event):
router.register(epoll)
console.register(epoll)
try:
router_fileno = router.fileno()
esc_quit = bytes(ESC_QUIT.upper(), 'ascii')
esc_state = False
while not stop_event.is_set():
event_list = epoll.poll(timeout=POLL_TIMEOUT)
# When/if the poll times out we send an empty datagram. If IOU
# has gone away then this will toss a ConnectionRefusedError
# exception.
if not event_list:
router.write(b'')
continue
for fileno, event in event_list:
buf = bytearray()
# IOU --> tty(s)
if fileno == router_fileno:
while not stop_event.is_set():
data = router.read(BUFFER_SIZE)
if not data:
break
buf.extend(data)
console.write(buf)
# tty --> IOU
else:
while not stop_event.is_set():
data = console.read(fileno, BUFFER_SIZE)
if not data:
break
buf.extend(data)
# If we just received the escape character then
# enter the escape state.
#
# If we are in the escape state then check for a
# quit command. Or if it's the escape character then
# send the escape character. Else, send the escape
# character we ate earlier and whatever character we
# just got. Exit escape state.
#
# If we're not in the escape state and this isn't an
# escape character then just send it to IOU.
if esc_state:
if buf.upper() == esc_quit:
sys.exit(EXIT_SUCCESS)
elif buf == esc_char:
router.write(esc_char)
else:
router.write(esc_char)
router.write(buf)
esc_state = False
elif buf == esc_char:
esc_state = True
else:
router.write(buf)
except ConnectionError as e:
pass
finally:
router.unregister(epoll)
console.unregister(epoll)
def get_args():
parser = argparse.ArgumentParser(
description='Connect to an IOU console port.')
parser.add_argument('-d', '--debug', action='store_true',
help='display some debugging information')
parser.add_argument('-e', '--escape',
help='set escape character (default: %(default)s)',
default=ESC_CHAR, metavar='CHAR')
parser.add_argument('-t', '--telnet-server',
help='start telnet server listening on ADDR:PORT',
metavar='ADDR:PORT', default=False)
parser.add_argument('-l', '--telnet-limit',
help='maximum number of simultaneous '
'telnet connections (default: %(default)s)',
metavar='LIMIT', type=int, default=1)
parser.add_argument('appl_id', help='IOU instance identifier')
return parser.parse_args()
def get_escape_character(escape):
# Figure out the escape character to use.
# Can be any ASCII character or a spelled out control
# character, like "^e". The string "none" disables it.
if escape.lower() == 'none':
esc_char = b''
elif len(escape) == 2 and escape[0] == '^':
c = ord(escape[1].upper()) - 0x40
if not 0 <= c <= 0x1f: # control code range
raise ConfigError("Invalid control code")
esc_char = bytes([c])
elif len(escape) == 1:
try:
esc_char = bytes(escape, 'ascii')
except ValueError as e:
raise ConfigError("Invalid escape character") from e
else:
raise ConfigError("Invalid length for escape character")
return esc_char
def start_ioucon(cmdline_args, stop_event):
global args
args = cmdline_args
if args.debug:
logging.basicConfig(level=logging.DEBUG)
else:
# default logging level
logging.basicConfig(level=logging.INFO)
# Create paths for the Unix domain sockets
netio = '/tmp/netio{}'.format(os.getuid())
ttyC = '{}/ttyC{}'.format(netio, args.appl_id)
ttyS = '{}/ttyS{}'.format(netio, args.appl_id)
try:
mkdir_netio(netio)
with FileLock(ttyC):
esc_char = get_escape_character(args.escape)
if args.telnet_server:
addr, _, port = args.telnet_server.partition(':')
nport = 0
try:
nport = int(port)
except ValueError:
pass
if addr == '' or nport == 0:
raise ConfigError('format for --telnet-server must be '
'ADDR:PORT (like 127.0.0.1:20000)')
while not stop_event.is_set():
epoll = select.epoll()
try:
if args.telnet_server:
with TelnetServer(addr, nport, stop_event) as console:
# We loop inside the Telnet server otherwise the client is disconnected when user use the reload command inside a terminal
while not stop_event.is_set():
try:
with IOU(ttyC, ttyS, stop_event) as router:
send_recv_loop(epoll, console, router, b'', stop_event)
except ConnectionRefusedError:
pass
else:
with IOU(ttyC, ttyS, stop_event) as router, TTY() as console:
send_recv_loop(epoll, console, router, esc_char, stop_event)
except ConnectionRefusedError:
pass
except KeyboardInterrupt:
sys.exit(EXIT_ABORT)
finally:
# Put us at the beginning of a line
if not args.telnet_server:
print()
except IOUConError as e:
if args.debug:
traceback.print_exc(file=sys.stderr)
else:
log.error("ioucon: {}".format(e))
sys.exit(EXIT_FAILURE)
log.info("exiting...")
def main():
import threading
stop_event = threading.Event()
args = get_args()
start_ioucon(args, stop_event)
if __name__ == '__main__':
main()