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ddp_specification_03.py
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ddp_specification_03.py
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#!/usr/bin/env python
# -*- coding: utf-8 -*-
#########################################################################
# Copyright/License Notice (BSD License) #
#########################################################################
#########################################################################
# Copyright (c) 2010-2012, Daniel Knaggs - 2E0DPK/M6DPK #
# All rights reserved. #
# #
# Redistribution and use in source and binary forms, with or without #
# modification, are permitted provided that the following conditions #
# are met: - #
# #
# * Redistributions of source code must retain the above copyright #
# notice, this list of conditions and the following disclaimer. #
# #
# * Redistributions in binary form must reproduce the above copyright #
# notice, this list of conditions and the following disclaimer in #
# the documentation and/or other materials provided with the #
# distribution. #
# #
# * Neither the name of the author nor the names of its contributors #
# may be used to endorse or promote products derived from this #
# software without specific prior written permission. #
# #
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS #
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT #
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR #
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT #
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, #
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT #
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, #
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY #
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT #
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE #
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. #
#########################################################################
###################################################
# Danny's Digital Packet #
# Danny's Data Packet #
# Danny's DDP Project #
###################################################
# Specification ID: 3 #
# Specification Name: SMS (Binary) #
###################################################
def constructPacket(self, callsign_from, via, callsign_to, flags, data, application_id, signature):
tx = bytearray()
p1 = bytearray()
p2 = bytearray()
p1.extend(self.PROTOCOL_HEADER)
p1.extend(self.SECTION_SEPERATOR)
p1.extend(self.PROTOCOL_VERSION)
p1.extend(self.SECTION_SEPERATOR)
p2.extend(callsign_from)
p2.extend(self.SECTION_SEPERATOR)
p2.extend(callsign_to)
p2.extend(self.SECTION_SEPERATOR)
p2.extend(str(hex(int(str(flags), 2))).replace("0x", ""))
p2.extend(self.SECTION_SEPERATOR)
p2.extend(self.encodeData(data, str(flags)))
signature = ""
checksum = self.xorChecksum(str(p2))
tx.extend(str(p1))
tx.extend(str(p2))
tx.extend(self.SECTION_SEPERATOR)
tx.extend(checksum)
tx.extend(self.SECTION_SEPERATOR)
tx.extend(self.PROTOCOL_FOOTER)
# Now we need apply the extra rules to the packet e.g. scrambling, reed-solomon, etc
if self.DEBUG_MODE:
self.log.info("Constructed: %s" % repr(str(tx)))
self.log.info("Applying rules to packet...")
d = str(tx)
tx2 = bytearray()
if self.fldigi is not None:
tx2.extend(d)
tx2.extend("\n")
tx2.extend("^r")
else:
tx2.extend(d)
if self.DEBUG_MODE:
a = float(len(str(tx)))
b = float(len(str(tx2)))
c = ((b - a) / a) * 100.
self.log.info("Original packet size %d bytes, including overhead %d bytes - %.2f%% increase." % (a, b, c))
return str(tx2)
def decodeData(self, data, flags):
f = str(flags)[::-1]
din = self.decodeBase128ToStream(str(data), 0, True)
din = self.descramble(din)
return din
def encodeData(self, data, flags):
din = str(data)
din = self.scramble(din)
return self.encodeStreamToBase128(din, 0, True)
def init(self):
self.SECTION_HEADER = 0
self.SECTION_VERSION = 1
self.SECTION_SOURCE = 2
self.SECTION_DESTINATION = 3
self.SECTION_FLAGS = 4
self.SECTION_DATA = 5
self.SECTION_CHECKSUM = 6
self.SECTION_FOOTER = 7
self.MAX_SECTIONS = 8
self.log.info("Running in SMS (hex encoded) mode.")
def isCompressionAllowed(self):
return False
def parsePacket(self, packet):
return packet
def splitPacket(self, packet):
return str(packet).split(self.SECTION_SEPERATOR)
def verifyPacket(self, packet):
plen = len(packet)
# Check the number of sections
if plen == self.MAX_SECTIONS:
# Check the header
if packet[self.SECTION_HEADER] == self.PROTOCOL_HEADER:
# Check the version number (must be exact versions for now)
if packet[self.SECTION_VERSION] == self.PROTOCOL_VERSION:
# Check the checksum
verify = packet[self.SECTION_SOURCE] + self.SECTION_SEPERATOR + packet[self.SECTION_DESTINATION] + self.SECTION_SEPERATOR + packet[self.SECTION_FLAGS] + self.SECTION_SEPERATOR + packet[self.SECTION_DATA]
checksum = self.xorChecksum(verify)
# Convert the flags to old-style
packet[self.SECTION_FLAGS] = bin(int(packet[self.SECTION_FLAGS], 16)).replace("0b", "").rjust(16, "0")
if checksum == packet[self.SECTION_CHECKSUM]:
# Application ID
if self.REPEATER_MODE:
# Set the application ID to the one we are verifying
self.APPLICATION_ID = packet[self.SECTION_APPLICATION_ID]
return True
else:
if self.DEBUG_MODE:
self.log.warn("Checksum mismatch (%s != %s)." % (checksum, packet[self.SECTION_CHECKSUM]))
else:
if self.DEBUG_MODE:
self.log.warn("Version number mismatch (%s != %s)." % (self.PROTOCOL_VERSION, packet[self.SECTION_VERSION]))
else:
if self.DEBUG_MODE:
self.log.warn("Invalid header (%s != %s)." % (self.PROTOCOL_HEADER, packet[self.SECTION_HEADER]))
else:
if self.DEBUG_MODE:
self.log.warn("Wrong number of sections (%d != %d)." % (plen, self.MAX_SECTIONS))
return False