# Copyright (C) 2011 Internet Systems Consortium, Inc. ("ISC")
#
# Permission to use, copy, modify, and distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SYSTEMS CONSORTIUM
# DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
# INTERNET SYSTEMS CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
# FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
# NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
# WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
import socket
import struct
import os
import errno
import copy
import subprocess
import copy
from isc.log_messages.bind10_messages import *
from libutil_io_python import recv_fd
logger = isc.log.Logger("boss")
"""
Module that comunicates with the privileged socket creator (b10-sockcreator).
"""
class CreatorError(Exception):
"""
Exception for socket creator related errors.
It has two members: fatal and errno and they are just holding the values
passed to the __init__ function.
"""
def __init__(self, message, fatal, error_num=None):
"""
Creates the exception. The message argument is the usual string.
The fatal one tells if the error is fatal (eg. the creator crashed)
and error_num is the errno value returned from socket creator, if
applicable.
"""
Exception.__init__(self, message)
self.fatal = fatal
self.errno = error_num
class Parser:
"""
This class knows the sockcreator language. It creates commands, sends them
and receives the answers and parses them.
It does not start it, the communication channel must be provided.
In theory, anything here can throw a fatal CreatorError exception, but it
happens only in case something like the creator process crashes. Any other
occasions are mentioned explicitly.
"""
def __init__(self, creator_socket):
"""
Creates the parser. The creator_socket is socket to the socket creator
process that will be used for communication. However, the object must
have a read_fd() method to read the file descriptor. This slightly
unusual trick with modifying an object is used to easy up testing.
You can use WrappedSocket in production code to add the method to any
ordinary socket.
"""
self.__socket = creator_socket
logger.info(BIND10_SOCKCREATOR_INIT)
def terminate(self):
"""
Asks the creator process to terminate and waits for it to close the
socket. Does not return anything. Raises a CreatorError if there is
still data on the socket, if there is an error closing the socket,
or if the socket had already been closed.
"""
if self.__socket is None:
raise CreatorError('Terminated already', True)
logger.info(BIND10_SOCKCREATOR_TERMINATE)
try:
self.__socket.sendall(b'T')
# Wait for an EOF - it will return empty data
eof = self.__socket.recv(1)
if len(eof) != 0:
raise CreatorError('Protocol error - data after terminated',
True)
self.__socket = None
except socket.error as se:
self.__socket = None
raise CreatorError(str(se), True)
def __addrport_str(self, address, port):
'''Convert a pair of IP address and port to common form for logging.'''
if address.family == socket.AF_INET:
return str(address) + ':' + str(port)
else:
return '[' + str(address) + ']:' + str(port)
def get_socket(self, address, port, socktype):
"""
Asks the socket creator process to create a socket. Pass an address
(the isc.net.IPaddr object), port number and socket type (either
string "UDP", "TCP" or constant socket.SOCK_DGRAM or
socket.SOCK_STREAM.
Blocks until it is provided by the socket creator process (which
should be fast, as it is on localhost) and returns the file descriptor
number. It raises a CreatorError exception if the creation fails.
"""
if self.__socket is None:
raise CreatorError('Socket requested on terminated creator', True)
# First, assemble the request from parts
logger.info(BIND10_SOCKET_GET, address, port, socktype)
data = b'S'
if socktype == 'UDP' or socktype == socket.SOCK_DGRAM:
data += b'U'
elif socktype == 'TCP' or socktype == socket.SOCK_STREAM:
data += b'T'
else:
raise ValueError('Unknown socket type: ' + str(socktype))
if address.family == socket.AF_INET:
data += b'4'
elif address.family == socket.AF_INET6:
data += b'6'
else:
raise ValueError('Unknown address family in address')
data += struct.pack('!H', port)
data += address.addr
try:
# Send the request
self.__socket.sendall(data)
answer = self.__socket.recv(1)
if answer == b'S':
# Success!
result = self.__socket.read_fd()
logger.info(BIND10_SOCKET_CREATED, result)
return result
elif answer == b'E':
# There was an error, read the error as well
error = self.__socket.recv(1)
rcv_errno = struct.unpack('i',
self.__read_all(len(struct.pack('i',
0))))
if error == b'S':
cause = 'socket'
elif error == b'B':
cause = 'bind'
else:
self.__socket = None
logger.fatal(BIND10_SOCKCREATOR_BAD_CAUSE, error)
raise CreatorError('Unknown error cause' + str(answer), True)
logger.error(BIND10_SOCKET_ERROR, cause, rcv_errno[0],
os.strerror(rcv_errno[0]))
# Provide as detailed information as possible on the error,
# as error related to socket creation is a common operation
# trouble. In particular, we are intentionally very verbose
# if it fails due to "permission denied" so the administrator
# can easily identify what is wrong and how to fix it.
addrport = self.__addrport_str(address, port)
error_text = 'Error creating socket on ' + cause + \
' to be bound to ' + addrport + ': ' + \
os.strerror(rcv_errno[0])
if rcv_errno[0] == errno.EACCES:
error_text += ' - probably need to restart BIND 10 ' + \
'as a super user'
raise CreatorError(error_text, False, rcv_errno[0])
else:
self.__socket = None
logger.fatal(BIND10_SOCKCREATOR_BAD_RESPONSE, answer)
raise CreatorError('Unknown response ' + str(answer), True)
except socket.error as se:
self.__socket = None
logger.fatal(BIND10_SOCKCREATOR_TRANSPORT_ERROR, str(se))
raise CreatorError(str(se), True)
def __read_all(self, length):
"""
Keeps reading until length data is read or EOF or error happens.
EOF is considered error as well and throws a CreatorError.
"""
result = b''
while len(result) < length:
data = self.__socket.recv(length - len(result))
if len(data) == 0:
self.__socket = None
logger.fatal(BIND10_SOCKCREATOR_EOF)
raise CreatorError('Unexpected EOF', True)
result += data
return result
class WrappedSocket:
"""
This class wraps a socket and adds a read_fd method, so it can be used
for the Parser class conveniently. It simply copies all its guts into
itself and implements the method.
"""
def __init__(self, socket):
# Copy whatever can be copied from the socket
for name in dir(socket):
if name not in ['__class__', '__weakref__']:
setattr(self, name, getattr(socket, name))
# Keep the socket, so we can prevent it from being garbage-collected
# and closed before we are removed ourself
self.__orig_socket = socket
def read_fd(self):
"""
Read the file descriptor from the socket.
"""
return recv_fd(self.fileno())
# FIXME: Any idea how to test this? Starting an external process doesn't sound
# OK
class Creator(Parser):
"""
This starts the socket creator and allows asking for the sockets.
Note: __process shouldn't be reset once created. See the note
of the SockCreator class for details.
"""
def __init__(self, path):
(local, remote) = socket.socketpair(socket.AF_UNIX, socket.SOCK_STREAM)
# Popen does not like, for some reason, having the same socket for
# stdin as well as stdout, so we dup it before passing it there.
remote2 = socket.fromfd(remote.fileno(), socket.AF_UNIX,
socket.SOCK_STREAM)
env = copy.deepcopy(os.environ)
env['PATH'] = path
# We explicitly set close_fs to True; it's False by default before
# Python 3.2. If we don't close the remaining FDs, the copy of
# 'local' will prevent the child process from terminating when
# the parent process died abruptly.
self.__process = subprocess.Popen(['b10-sockcreator'], env=env,
stdin=remote.fileno(),
stdout=remote2.fileno(),
close_fds=True,
preexec_fn=self.__preexec_work)
remote.close()
remote2.close()
Parser.__init__(self, WrappedSocket(local))
def __preexec_work(self):
"""Function used before running a program that needs to run as a
different user."""
# Put us into a separate process group so we don't get
# SIGINT signals on Ctrl-C (the boss will shut everthing down by
# other means).
os.setpgrp()
def pid(self):
return self.__process.pid
def kill(self):
logger.warn(BIND10_SOCKCREATOR_KILL)
if self.__process is not None:
self.__process.kill()