DMRlink/bridge.py

#!/usr/bin/env python
#
# This work is licensed under the Creative Commons Attribution-ShareAlike
# 3.0 Unported License.To view a copy of this license, visit
# http://creativecommons.org/licenses/by-sa/3.0/ or send a letter to
# Creative Commons, 444 Castro Street, Suite 900, Mountain View,
# California, 94041, USA.

# This is a sample application to bridge traffic between IPSC networks. it uses
# one required (bridge_rules.py) and one optional (known_bridges.py) additional
# configuration files. Both files have their own documentation for use.
#
# "bridge_rules" contains the IPSC network, Timeslot and TGID matching rules to
# determine which voice calls are bridged between IPSC networks and which are
# not.
#
# "known_bridges" contains DMR radio ID numbers of known bridges. This file is
# used when you want bridge.py to be "polite" or serve as a backup bridge. If
# a known bridge exists in either a source OR target IPSC network, then no
# bridging between those IPSC networks will take place. This behavior is
# dynamic and updates each keep-alive interval (main configuration file).
# For faster failover, configure a short keep-alive time and a low number of
# missed keep-alives before timout. I recommend 5 sec keep-alive and 3 missed.
# That gives a worst-case scenario of 15 seconds to fail over. Recovery will
# typically happen with a single "blip" in the transmission up to about 5
# seconds.
#
# While this file is listed as Beta status, K0USY Group depends on this code
# for the bridigng of it's many repeaters. We consider it reliable, but you
# get what you pay for... as usual, no guarantees.

from __future__ import print_function
from twisted.internet import reactor
from twisted.internet import task
from binascii import b2a_hex as h
from time import time

import sys
from dmrlink import IPSC, NETWORK, networks, dmr_nat, logger, hex_str_3, hex_str_4, int_id

__author__ = 'Cortney T. Buffington, N0MJS'
__copyright__ = 'Copyright (c) 2013-2015 Cortney T. Buffington, N0MJS and the K0USY Group'
__credits__ = 'Adam Fast, KC0YLK, Dave K, and he who wishes not to be named'
__license__ = 'Creative Commons Attribution-ShareAlike 3.0 Unported'
__version__ = '0.28b'
__maintainer__ = 'Cort Buffington, N0MJS'
__email__ = 'n0mjs@me.com'
__status__ = 'beta'


# Constants for this application
#
BURST_DATA_TYPE = {
    'VOICE_HEAD':  '\x01',
    'VOICE_TERM':  '\x02',
    'SLOT1_VOICE': '\x0A',
    'SLOT2_VOICE': '\x8A'   
}
TS_CLEAR_TIME = .2

# Import Bridging rules
# Note: A stanza *must* exist for any IPSC configured in the main
# configuration file and listed as "active". It can be empty, 
# but it has to exist.
#
try:
    from bridge_rules import RULES
    logger.info('Bridge rules file found and rules imported')
except ImportError:
    sys.exit('Bridging rules file not found or invalid')

# Convert integer GROUP ID numbers from the config into hex strings
# we need to send in the actual data packets.
#

for _ipsc in RULES:
    for _rule in RULES[_ipsc]['GROUP_VOICE']:
        _rule['SRC_GROUP'] = hex_str_3(_rule['SRC_GROUP'])
        _rule['DST_GROUP'] = hex_str_3(_rule['DST_GROUP'])
        _rule['SRC_TS'] = _rule['SRC_TS'] - 1
        _rule['DST_TS'] = _rule['DST_TS'] - 1


# Import List of Bridges
# This is how we identify known bridges. If one of these is present
# and it's mode byte is set to bridge, we don't
#
try:
    from known_bridges import BRIDGES
    logger.info('Known bridges file found and bridge ID list imported ')
except ImportError:
    logger.critical('\'known_bridges.py\' not found - backup bridge service will not be enabled')
    BRIDGES = []


class bridgeIPSC(IPSC):
    def __init__(self, *args, **kwargs):
        IPSC.__init__(self, *args, **kwargs)
        if BRIDGES:
            logger.info('Initializing backup/polite bridging')
            self.BRIDGE = False
        else:
            self.BRIDGE = True
            logger.info('Initializing standard bridging')
        
        self.IPSC_STATUS = {
            'TS1': {'RX_GROUP':'\x00', 'TX_GROUP':'\x00', 'RX_TIME':0, 'TX_TIME':0, 'RX_SRC_SUB':'\x00', 'TX_SRC_SUB':'\x00'},
            'TS2': {'RX_GROUP':'\x00', 'TX_GROUP':'\x00', 'RX_TIME':0, 'TX_TIME':0, 'RX_SRC_SUB':'\x00', 'TX_SRC_SUB':'\x00'}
        }
        
    # Setup the backup/polite bridging maintenance loop (based on keep-alive timer)
    
    if BRIDGES:
        def startProtocol(self):
            IPSC.startProtocol(self)

            self._bridge_presence = task.LoopingCall(self.bridge_presence_loop)
            self._bridge_presence_loop = self._bridge_presence.start(self._local['ALIVE_TIMER'])

    # This is the backup/polite bridge maintenance loop
    def bridge_presence_loop(self):
        _temp_bridge = True
        for peer in BRIDGES:
            _peer = hex_str_4(peer)
        
            if _peer in self._peers.keys() and (self._peers[_peer]['MODE_DECODE']['TS_1'] or self._peers[_peer]['MODE_DECODE']['TS_2']):
                _temp_bridge = False
                logger.debug('(%s) Peer %s is an active bridge', self._network, int_id(_peer))
        
            if _peer == self._master['RADIO_ID'] \
                and self._master['STATUS']['CONNECTED'] \
                and (self._master['MODE_DECODE']['TS_1'] or self._master['MODE_DECODE']['TS_2']):
                _temp_bridge = False
                logger.debug('(%s) Master %s is an active bridge',self._network, int_id(_peer))
        
        if self.BRIDGE != _temp_bridge:
            logger.info('(%s) Changing bridge status to: %s', self._network, _temp_bridge )
        self.BRIDGE = _temp_bridge

    
    #************************************************
    #     CALLBACK FUNCTIONS FOR USER PACKET TYPES
    #************************************************
    #
    def group_voice(self, _network, _src_sub, _dst_group, _ts, _end, _peerid, _data):
        logger.debug('(%s) Group Voice Packet Received From: %s, IPSC Peer %s, Destination %s', _network, int_id(_src_sub), int_id(_peerid), int_id(_dst_group))
        _burst_data_type = _data[30] # Determine the type of voice packet this is (see top of file for possible types)
        if _ts == 0:
            _TS = 'TS1'
        elif _ts == 1:
            _TS = 'TS2'
        
        for rule in RULES[_network]['GROUP_VOICE']:
            _target = rule['DST_NET']               # Shorthand to reduce length and make it easier to read
            _status = networks[_target].IPSC_STATUS # Shorthand to reduce length and make it easier to read
            now = time()                            # Mark packet arrival time -- we'll need this for call contention handling 
                    
            # Matching for rules is against the Destination Group in the SOURCE packet (SRC_GROUP)
            #if rule['SRC_GROUP'] == _dst_group and rule['SRC_TS'] == _ts:
            #if BRIDGES:
            if (rule['SRC_GROUP'] == _dst_group and rule['SRC_TS'] == _ts) and (self.BRIDGE == True or networks[_target].BRIDGE == True):
                
                if ((rule['DST_GROUP'] != _status[_TS]['RX_GROUP']) and ((now - _status[_TS]['RX_TIME']) < RULES[_network]['GROUP_HANGTIME'])):
                    if _burst_data_type == BURST_DATA_TYPE['VOICE_HEAD']:
                        logger.info('(%s) Call not bridged, target active or in group hangtime: IPSC %s, %s, TGID%s', _network, _target, _TS, int_id(rule['DST_GROUP']))
                    return
                    
                if ((rule['DST_GROUP'] != _status[_TS]['TX_GROUP']) and ((now - _status[_TS]['TX_TIME']) < RULES[_network]['GROUP_HANGTIME'])):
                    if _burst_data_type == BURST_DATA_TYPE['VOICE_HEAD']:
                        logger.info('(%s) Call not bridged, target in group hangtime: IPSC %s, %s, TGID%s', _network, _target, _TS, int_id(rule['DST_GROUP']))
                    return

                if (rule['DST_GROUP'] == _status[_TS]['TX_GROUP']) and (_src_sub != _status[_TS]['TX_SRC_SUB']) and ((now - _status[_TS]['TX_TIME']) < TS_CLEAR_TIME):
                    if _burst_data_type == BURST_DATA_TYPE['VOICE_HEAD']:
                        logger.info('(%s) Call not bridged, call bridge in progress from %s, target: IPSC %s, %s, TGID%s', _network, int_id(_src_sub), _target, _TS, int_id(rule['DST_GROUP']))
                    return

                if (rule['DST_GROUP'] == _status[_TS]['RX_GROUP']) and ((now - _status[_TS]['RX_TIME']) < TS_CLEAR_TIME):
                    if _burst_data_type == BURST_DATA_TYPE['VOICE_HEAD']:
                        logger.info('(%s) Call not bridged, matching call already active on target: IPSC %s, %s, TGID%s', _network, _target, _TS, int_id(rule['DST_GROUP']))
                    return
                       
                _tmp_data = _data
                # Re-Write the IPSC SRC to match the target network's ID
                _tmp_data = _tmp_data.replace(_peerid, NETWORK[_target]['LOCAL']['RADIO_ID'])
                # Re-Write the destination Group ID
                _tmp_data = _tmp_data.replace(_dst_group, rule['DST_GROUP'])
            
                # Re-Write IPSC timeslot value
                _call_info = int_id(_data[17:18])
                if rule['DST_TS'] == 0:
                    _call_info &= ~(1 << 5)
                elif rule['DST_TS'] == 1:
                    _call_info |= 1 << 5
                _call_info = chr(_call_info)
                _tmp_data = _tmp_data[:17] + _call_info + _tmp_data[18:] 
                
                # Re-Write DMR timeslot value
                # Determine if the slot is present, so we can translate if need be
                if _burst_data_type == BURST_DATA_TYPE['SLOT1_VOICE'] or _burst_data_type == BURST_DATA_TYPE['SLOT2_VOICE']:
                    _slot_valid = True
                else:
                    _slot_valid = False
                # Re-Write timeslot if necessary...
                if _slot_valid:
                    if rule['DST_TS'] == 0:
                        _burst_data_type = BURST_DATA_TYPE['SLOT1_VOICE']
                    elif rule['DST_TS'] == 1:
                        _burst_data_type = BURST_DATA_TYPE['SLOT2_VOICE']
                    _tmp_data = _tmp_data[:30] + _burst_data_type + _tmp_data[31:]
            
                # Calculate and append the authentication hash for the target network... if necessary
                if NETWORK[_target]['LOCAL']['AUTH_ENABLED']:
                    _tmp_data = self.hashed_packet(NETWORK[_target]['LOCAL']['AUTH_KEY'], _tmp_data)
                # Send the packet to all peers in the target IPSC
                networks[_target].send_to_ipsc(_tmp_data)

                _status[_TS]['TX_GROUP'] = _dst_group
                _status[_TS]['TX_TIME'] = now
                _status[_TS]['TX_SRC_SUB'] = _src_sub

        # Mark the group and time that a packet was recieved
        self.IPSC_STATUS[_TS]['RX_GROUP'] = _dst_group
        self.IPSC_STATUS[_TS]['RX_TIME'] = now



if __name__ == '__main__':
    logger.info('DMRlink \'bridge.py\' (c) 2013-2015 N0MJS & the K0USY Group - SYSTEM STARTING...')
    for ipsc_network in NETWORK:
        if NETWORK[ipsc_network]['LOCAL']['ENABLED']:
            networks[ipsc_network] = bridgeIPSC(ipsc_network)
            reactor.listenUDP(NETWORK[ipsc_network]['LOCAL']['PORT'], networks[ipsc_network], interface=NETWORK[ipsc_network]['LOCAL']['IP'])
    
    reactor.run()