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######################################################################
# XTalk - A BSD talk client written in Python.
# (C) Adam P. Jenkins <adampjenkins@yahoo.com>
#
# 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 2
# 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, write to the Free Software
# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
#
######################################################################
# Implements the C structures for talking to a talk daemon
import struct, re, socket, string
# This modules defines classes necessary to communicate with a talk
# daemon. The talk daemon requires communication via binary data
# structures, so this module provides an interface. There are three
# classes defined, which correspond to C structures. Each of them has
# a method, toCStruct(), which returns a string containing the proper
# binary representation of the structure, and a method,
# fromCStruct(str), which takes such a binary string, and initializes
# itself from the binary string. Each class also has a "size"
# attribute which returns its size in bytes.
# The classes are:
#
# sockaddr_in:
# family # one of the family constants from socket module
# port # a port number
# address # an address in cannonical or number-dot format
#
# CTL_MSG:
#
# CTL_RESPONSE
# The declaration for sockaddr is
# struct sockaddr {
# unsigned short family; /* AF_* */
# char sa_data[14]; /* the resto of the data */
# };
#
# sizeof(sockaddr) == 16
#
# What's the rest of the data. Normally it's a sockaddr_in.
# struct in_addr {
# __u32 s_addr;
# };
#
# struct sockaddr_in {
# short family;
# short port;
# struct in_addr;
# /* plus padding to fill out to the size of a sockaddr. */
# };
#
TALK_VERSION = 1
# message types
LEAVE_INVITE = 0
LOOK_UP = 1
DELETE = 2
ANNOUNCE = 3
# response types
SUCCESS = 0
NOT_HERE = 1
FAILED = 2
MACHINE_UNKNOWN = 3
PERMISSION_DENIED = 4
UNKNOWN_REQUEST = 5
BADVERSION = 6
BADADDR = 7
BADCTLADDR = 8
def htons(n):
return struct.pack('BB', n >> 8, n & 0xff)
def htonl(n):
return struct.pack('!l', n)
def htonb(n):
return struct.pack('B', n)
def ntohs(n):
hi, low = struct.unpack('BB', n)
return ((hi & 0xff) << 8) + (low & 0xff)
def ntohl(n):
tmp = struct.unpack('4B', n)
return (((tmp[0] & 0xff) << 24) +
((tmp[1] & 0xff) << 16) +
((tmp[2] & 0xff) << 8) +
(tmp[3] & 0xff))
def ntohb(n):
tmp = struct.unpack('B', n)
return (tmp[0] & 0xff)
class sockaddr_in:
size = 16
def __init__(self, family=0, port=0, addr='0.0.0.0'):
self.family = family
self.port = port
self.address = addr
# returns the equivalent of a sockaddr_in, already in network byte
# order.
def toCStruct(self):
# make sure address is in numbers-dots notation
addr = socket.gethostbyname(self.address)
# break it up into components
#addr = regsub.split(addr, '\.')
addr = string.split(addr, '.')
# and convert them to numbers
addr = map(string.atoi, addr)
return (htons(self.family) + htons(self.port) +
struct.pack('4B8x', addr[0], addr[1], addr[2], addr[3]))
def fromCStruct(self, str):
self.family = ntohs(str[0:2])
self.port = ntohs(str[2:4])
addr = struct.unpack('BBBB', str[4:8])
addr = map(lambda x: x & 0xff, addr)
self.address = '%d.%d.%d.%d' % (addr[0], addr[1], addr[2], addr[3])
class CTL_MSG:
size = 84
version = TALK_VERSION
type = 0
idNum = 0
addr = sockaddr_in()
ctlAddr = sockaddr_in()
pid = 0
localName = ''
remoteName = ''
remoteTTY = ''
def toCStruct(self):
return (htonb(self.version) + htonb(self.type) + htons(0) +
htonl(self.idNum) + self.addr.toCStruct() +
self.ctlAddr.toCStruct() + htonl(self.pid) +
self.localName + ('\0' * (12 - len(self.localName))) +
self.remoteName + ('\0' * (12 - len(self.remoteName))) +
self.remoteTTY + ('\0' * (16 - len(self.remoteTTY))))
def fromCStruct(self, str):
self.version = ntohb(str[0])
self.type = ntohb(str[1])
self.idNum = ntohl(str[4:8])
self.addr.fromCStruct(str[8:24])
self.ctlAddr.fromCStruct(str[24:40])
self.pid = ntohl(str[40:44])
self.localName = re.sub('\0*$', '', str[44:56])
self.remoteName = re.sub('\0*$', '', str[56:68])
self.remoteTTY = re.sub('\0*$', '', str[68:84])
class CTL_RESPONSE:
size = 24
version = TALK_VERSION
type = 0
answer = 0
idNum = 0
addr = sockaddr_in()
def toCStruct(self):
return (struct.pack('bbbx', self.version, self.type,
self.answer) +
htonl(self.idNum) + self.addr.toCStruct())
def fromCStruct(self, str):
self.version = ntohb(str[0])
self.type = ntohb(str[1])
self.answer = ntohb(str[2])
self.idNum = ntohl(str[4:8])
self.addr.fromCStruct(str[8:24])
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