I'm trying to modify the simple python script provided with my Pipsta Printer so that instead of printing a single line of text, it prints out a list of things.
I know there are probably better ways to do this, but using the script below, could somebody please tell me what changes I need to make around the "txt = " part of the script, so that I can print out a list of items and not just one item?
Thanks.
# BasicPrint.py
# Copyright (c) 2014 Able Systems Limited. All rights reserved.
'''This simple code example is provided as-is, and is for demonstration
purposes only. Able Systems takes no responsibility for any system
implementations based on this code.
This very simple python script establishes USB communication with the Pipsta
printer sends a simple text string to the printer.
Copyright (c) 2014 Able Systems Limited. All rights reserved.
'''
import argparse
import platform
import sys
import time
import usb.core
import usb.util
FEED_PAST_CUTTER = b'\n' * 5
USB_BUSY = 66
# NOTE: The following section establishes communication to the Pipsta printer
# via USB. YOU DO NOT NEED TO UNDERSTAND THIS SECTION TO PROGRESS WITH THE
# TUTORIALS! ALTERING THIS SECTION IN ANY WAY CAN CAUSE A FAILURE TO COMMUNICATE
# WITH THE PIPSTA. If you are interested in learning about what is happening
# herein, please look at the following references:
#
# PyUSB: http://sourceforge.net/apps/trac/pyusb/
# ...which is a wrapper for...
# LibUSB: http://www.libusb.org/
#
# For full help on PyUSB, at the IDLE prompt, type:
# >>> import usb
# >>> help(usb)
# 'Deeper' help can be trawled by (e.g.):
# >>> help(usb.core)
#
# or at the Linux prompt, type:
# pydoc usb
# pydoc usb.core
PIPSTA_USB_VENDOR_ID = 0x0483
PIPSTA_USB_PRODUCT_ID = 0xA053
def parse_arguments():
'''Parse the arguments passed to the script looking for a font file name
and a text string to print. If either are mssing defaults are used.
'''
txt = 'Hello World from Pipsta!'
parser = argparse.ArgumentParser()
parser.add_argument('text', help='the text to print',
nargs='*', default=txt.split())
args = parser.parse_args()
return ' '.join(args.text)
def main():
"""The main loop of the application. Wrapping the code in a function
prevents it being executed when various tools import the code.
"""
if platform.system() != 'Linux':
sys.exit('This script has only been written for Linux')
# Find the Pipsta's specific Vendor ID and Product ID
dev = usb.core.find(idVendor=PIPSTA_USB_VENDOR_ID,
idProduct=PIPSTA_USB_PRODUCT_ID)
if dev is None: # if no such device is connected...
raise IOError('Printer not found') # ...report error
try:
# Linux requires USB devices to be reset before configuring, may not be
# required on other operating systems.
dev.reset()
# Initialisation. Passing no arguments sets the configuration to the
# currently active configuration.
dev.set_configuration()
except usb.core.USBError as ex:
raise IOError('Failed to configure the printer', ex)
# The following steps get an 'Endpoint instance'. It uses
# PyUSB's versatile find_descriptor functionality to claim
# the interface and get a handle to the endpoint
# An introduction to this (forming the basis of the code below)
# can be found at:
cfg = dev.get_active_configuration() # Get a handle to the active interface
interface_number = cfg[(0, 0)].bInterfaceNumber
# added to silence Linux complaint about unclaimed interface, it should be
# release automatically
usb.util.claim_interface(dev, interface_number)
alternate_setting = usb.control.get_interface(dev, interface_number)
interface = usb.util.find_descriptor(
cfg, bInterfaceNumber=interface_number,
bAlternateSetting=alternate_setting)
usb_endpoint = usb.util.find_descriptor(
interface,
custom_match=lambda e:
usb.util.endpoint_direction(e.bEndpointAddress) ==
usb.util.ENDPOINT_OUT
)
if usb_endpoint is None: # check we have a real endpoint handle
raise IOError("Could not find an endpoint to print to")
# Now that the USB endpoint is open, we can start to send data to the
# printer.
# The following opens the text_file, by using the 'with' statemnent there is
# no need to close the text_file manually. This method ensures that the
# close is called in all situation (including unhandled exceptions).
txt = parse_arguments()
usb_endpoint.write(b'\x1b!\x00')
# Print a char at a time and check the printers buffer isn't full
for x in txt:
usb_endpoint.write(x) # write all the data to the USB OUT endpoint
res = dev.ctrl_transfer(0xC0, 0x0E, 0x020E, 0, 2)
while res[0] == USB_BUSY:
time.sleep(0.01)
res = dev.ctrl_transfer(0xC0, 0x0E, 0x020E, 0, 2)
usb_endpoint.write(FEED_PAST_CUTTER)
usb.util.dispose_resources(dev)
# Ensure that BasicPrint is ran in a stand-alone fashion (as intended) and not
# imported as a module. Prevents accidental execution of code.
if __name__ == '__main__':
main()
Pipsta uses linux line-feed ('\n', 0x0A, 10 in decimal) to mark a new line. For a quick test change BasicPrint.py as follows:
#txt = parse_arguments()
txt = 'Recipt:\n========\n1. food 1 - 100$\n2. drink 1 - 200$\n\n\n\n\n'
usb_endpoint.write(b'\x1b!\x00')
for x in txt:
usb_endpoint.write(x)
res = dev.ctrl_transfer(0xC0, 0x0E, 0x020E, 0, 2)
while res[0] == USB_BUSY:
time.sleep(0.01)
res = dev.ctrl_transfer(0xC0, 0x0E, 0x020E, 0, 2)
I commented out parameter parsing and injected a test string with multi line content.
Related
How to monitor and read Ubuntu's "Night Light" status via D-Bus using Python with dasbus? I can't figure out the API docs on how to read a property or subscribe to a signal.
Likely candidates:
dasbus.client.property.get()
GLibClient.subscribe()
The following is adapted from the basic examples and prints the interfaces and properties/signals of the object:
#!/usr/bin/env python3
from dasbus.connection import SessionMessageBus
bus = SessionMessageBus()
# dasbus.client.proxy.ObjectProxy
proxy = bus.get_proxy(
"org.gnome.SettingsDaemon.Color", # bus name
"/org/gnome/SettingsDaemon/Color", # object path
)
print(proxy.Introspect())
# read and print properties "NightLightActive" and "Temperature" from interface "org.gnome.SettingsDaemon.Color" in (callback) function
# subscribe to signal "PropertiesChanged" in interface "org.freedesktop.DBus.Properties" / register callback function
Resources
https://pypi.org/project/dbus-python/
What is recommended to use pydbus or dbus-python and what are the differences?
https://wiki.python.org/moin/DbusExamples
Migration from dbus to GDbus in Python 3
Looking at the dasbus examples and the Introspection data it looks like to get the property the dasbus is pythonic so proxy.<property name> works. For your example of NightLightActive it would be:
print("Night light active?", proxy.NightLightActive)
For the signal you need to connect to the signal on the proxy so that seems to take the form of proxy.<signal name>.connect so for example:
proxy.PropertiesChanged.connect(callback)
And this will need to have an EventLoop running.
My entire test was:
from dasbus.connection import SessionMessageBus
from dasbus.loop import EventLoop
bus = SessionMessageBus()
loop = EventLoop()
# dasbus.client.proxy.ObjectProxy
proxy = bus.get_proxy(
"org.gnome.SettingsDaemon.Color", # bus name
"/org/gnome/SettingsDaemon/Color", # object path
)
print("Night light active?", proxy.NightLightActive)
print("Temperature is set to:", proxy.Temperature)
def callback(iface, prop_changed, prop_invalidated):
print("The notification:",
iface, prop_changed, prop_invalidated)
proxy.PropertiesChanged.connect(callback)
loop.run()
I am working on a project with TwinCat and AMR. I'm using Python as a communication medium between the two systems. I have an issue with waiting for the variable to change value. I have a variable of type BOOL and want to perform a certain action when the variable changes. Can someone help me with this?
P.S. I have notified for change in variable as well.
import pyads
PLC = pyads.Connection('127.0.0.1.1.1', pyads.PORT_SPS1)
PLC.open()
StnF = PLC.read_by_name('GVL.AGVgotoStnF', pyads.PLCTYPE_BOOL)
print(StnF)
if StnF == 'TRUE' :
ArrStnF = PLC.write_by_name('GVL.iPosAGV',3,pyads.PLCTYPE_INT)
print(ArrStnF)
Your looking for notifications. The documentation of pyads gives and example how to do this:
import pyads
from ctypes import sizeof
# define the callback which extracts the value of the variable
def callback(notification, data):
contents = notification.contents
var = next(map(int, bytearray(contents.data)[0:contents.cbSampleSize]))
plc = pyads.Connection('127.0.0.1.1.1', pyads.PORT_SPS1)
plc.open()
attr = pyads.NotificationAttrib(sizeof(pyads.PLCTYPE_INT))
# add_device_notification returns a tuple of notification_handle and
# user_handle which we just store in handles
handles = plc.add_device_notification('GVL.integer_value', attr, callback)
# To remove the device notification just use the del_device_notication
# function.
plc.del_device_notification(*handles)
I'm trying to construct a man in the middle attack on a webpage (i.e. HTTP traffic). I'm doing this by using a Linux machine attached to Ethernet and a client attached to the Linux box via its WiFi hotspot.
What I've done so far is use NFQueue from within the IPTables Linux firewall to route all TCP packets on the FORWARD chain to the NFQueue queue, which a Python script is picking up and then processing those rules. I'm able to read the data off of the HTTP response packets, but whenever I try to modify them and pass them back (accept the packets), I'm getting an error regarding the strings:
Exception AttributeError: "'str' object has no attribute 'build_padding'" in 'netfilterqueue.global_callback' ignored
My code is here, which includes things that I've tried that didn't work. Notably, I'm using a third-party extension for scapy called scapy_http that may be interfering with things, and I'm using a webpage that is not being compressed by gzip because that was messing with things as well. The test webpage that I'm using is here.
#scapy
from scapy.all import *
#nfqueue import
from netfilterqueue import NetfilterQueue
#scapy http extension, not really needed
import scapy_http.http
#failed gzip decoding, also tried some other stuff
#import gzip
def print_and_accept(packet):
#convert nfqueue datatype to scapy-compatible
pkt = IP(packet.get_payload())
#is this an HTTP response?
if pkt[TCP].sport == 80:
#legacy trial that doesn't work
#data = packet.get_data()
print('HTTP Packet Found')
#check what's in the payload
stringLoad = str(pkt[TCP].payload)
#deleted because printing stuff out clogs output
#print(stringLoad)
#we only want to modify a specific packet:
if "<title>Acids and Bases: Use of the pKa Table</title>" in stringLoad:
print('Target Found')
#strings kind of don't work, I think this is a me problem
#stringLoad.replace('>Acids and Bases: Use of the pK<sub>a</sub>', 'This page has been modified: a random ')
#pkt[TCP].payload = stringLoad
#https://stackoverflow.com/questions/27293924/change-tcp-payload-with-nfqueue-scapy
payload_before = len(pkt[TCP].payload)
# I suspect this line is a problem: the string assigns,
# but maybe under the hood scapy doesn't like that very much
pkt[TCP].payload = str(pkt[TCP].payload).replace("Discussion", "This page has been modified")
#recalculate length
payload_after = len(pkt[TCP].payload)
payload_dif = payload_after - payload_before
pkt[IP].len = pkt[IP].len + payload_dif
#recalculate checksum
del pkt[TCP].chksum
del pkt[IP].chksum
del pkt.chksum
print('Packet Modified')
#redudant
#print(stringLoad)
#this throws an error (I think)
print(str(pkt[TCP].payload))
#no clue if this works or not yet
#goal here is to reassign modified packet to original parameter
packet.set_payload(str(pkt))
#this was also throwing the error, so tried to move away from it
#print(pkt.show2())
#bunch of legacy code that didn't work
#print(GET_print(pkt))
#print(pkt.show())
#decompressed_data = zlib.decompress(str(pkt[TCP].payload), 16 + zlib.MAX_WBITS)
#print(decompressed_data)
#print(str(gzip.decompress(pkt[TCP].payload)))
# print(pkt.getlayer(Raw).load)
#print('HTTP Contents Shown')
packet.accept()
def GET_print(packet1):
ret = "***************************************GET PACKET****************************************************\n"
ret += "\n".join(packet1.sprintf("{Raw:%Raw.load%}\n").split(r"\r\n"))
ret += "*****************************************************************************************************\n"
return ret
print('Test: Modify a very specific target')
print('Program Starting')
nfqueue = NetfilterQueue()
nfqueue.bind(1, print_and_accept)
try:
print('Packet Interface Starting')
nfqueue.run()
except KeyboardInterrupt:
print('\nProgram Ending')
nfqueue.unbind()
Apologies in advance if this is hard to read or badly formatted code; Python isn't a language that I write in often. Any help is greatly appreciated!
I'm trying to filter certain packets with protocols using user input from a given pcap file and than move the packets to a new pcap file.
That the code I made so far:
# ===================================================
# Imports
# ===================================================
from scapy.all import *
from scapy.utils import PcapWriter
"""
your going to need to install the modules below
"""
from Tkinter import Tk
from tkFileDialog import askopenfilename
# ===================================================
# Constants
# ===================================================
#OS commands:
#~~~~~~~~~~~~~
if "linux2" in sys.platform:
"""
linux based system clear command
"""
CLEAR_COMMAND = "clear"
elif "win32" in sys.platform:
"""
windows based system clear command
"""
CLEAR_COMMAND = "cls"
elif "cygwin" in sys.platform:
"""
crygwin based clear command
"""
CLEAR_COMMAND = "printf \"\\033c\""
elif "darwin" in sys.platform:
"""
mac OS X based clear command
"""
CLEAR_COMMAND = "printf \'\\33c\\e[3J\'"
#Usage string:
#~~~~~~~~~~~~~~
FILE_STRING = "please choose a pcap file to use"
BROWSE_STRING = "press any key to browser files\n"
BAD_PATH_STRING = "bad file please try agien\n"
BAD_INPUT_STRING = "bad input please try agien\n"
PROTOCOL_STRING = "please enter the protocol you wish to filter\n"
NAME_STRING = "please enter the new pcap file name\n"
# ===================================================
# Code
# ===================================================
def filter_pcap():
"""
filtering from the given pcap file a protocol the user chooce (from any layer in the OSI model)
and than asks for a new pcap file name, than filters the given protocol to a new pcap file
:param none
:return nothing:
"""
path = file_browse()
i = 0
filtertype = raw_input(PROTOCOL_STRING)
name = raw_input(NAME_STRING)
packs = rdpcap(path)
for i in range(len(packs)):
if filtertype in packs[i]:
wrpcap(name +".pcap", packs[i])
def file_browse():
"""
Purpose: It will allow the user to browse files on his computer
than it will check if the path is ok and will return it
:returns - the path to the chosen pcap file
"""
path = "test"
while ".pcap" not in path:
print FILE_STRING
raw_input(BROWSE_STRING)
os.system(CLEAR_COMMAND)
Tk().withdraw()
path = askopenfilename()
if ".pcap" not in path:
print BAD_PATH_STRING
return path
filter_pcap()
Now the problem is that I'm failing to filter the packets correctly.
The code need to filter protocols from any layer and any kind.
I have checked that thread: How can I filter a pcap file by specific protocol using python?
But as you can see it was not answered and the user added the problems I had in the edit, if any one could help me it would be great
Example for how it should work:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
lets say i use the file "sniff" as my first pcap file and it has 489 packets when 200 from those packets are http packets.
now there is that print:
please enter the protocol you wish to filter
'http'
and than there is the print:
please enter the new pcap file name
'new'
the user input was 'http' now the program will search for every packet that run on http protocol and will create a new pcap file called 'new.pcap'.
the file 'new.pcap' will contain 200 http packets.
now that thing should work with any protocol on the OSI model including protocols like IP, TCP, Ethernet and so on (all the protocols in the ascii model).
I have found out that wireshark command line has the option -R and tshark has .protocols, but it dont really work... Can any one check that?
edit: i found pyshark but i dont know how to write with it
I don't believe that scapy has any functions or methods to support application layer protocols in the way that you are after. However, using sport and dport as a filter will do the trick (provided you are going to see/are expecting default ports).
Try something like this:
def filter_pcap(filtertype = None):
..... snip .....
# Static Dict of port to protocol values. Like so:
protocols = {'http': 80, 'ssh': 22, 'telnet': 21}
# Check to see if it is in the list
while filtertype not in protocols:
filtertype = raw_input(PROTOCOL_STRING)
# Name for output file
name = raw_input(NAME_STRING)
# Read Input File
packs = rdpcap(path)
# Filters to only TCP packets
for packet in packs[TCP]:
# Filter only the proto (aka Port) that we want
if protocols[filtertype] in packet.sport or protocols[filtertype] in packet.dport :
# Write to file
wrpcap(name +".pcap", packet)
I am using python to read data from a USB input device. I would like to know if there is a way this could be exchanged with the model in MATLAB real-time. How I do it now is to save the data read in a .mat file and then let the model read it from there, which is not very intuitive.The code I use for this is as below:
#Import the needed libraries
import usb.core,usb.util,sys,time
import sys
from array import *
import scipy.io
#find our device
dev = usb.core.find(idVendor=0x046d, idProduct=0xc29a)
# was it found?
if dev is None:
raise ValueError('Device not found')
# set the active configuration. With no arguments, the first
# configuration will be the active one
try:
dev.set_configuration()
#In the event of an error
except usb.core.USBError as e:
print('Cannot set configuration the device: %s' %str(e))
sys.exit()
# get an endpoint instance
cfg = dev.get_active_configuration()
intf = cfg[(0,0)]
ep = usb.util.find_descriptor(
intf,
# match the first IN endpoint
custom_match = \
lambda e: \
usb.util.endpoint_direction(e.bEndpointAddress) == \
usb.util.ENDPOINT_IN)
#Initialising variables
#Databases for access in MATLAB
gas_pedal_data={}
brake_pedal_data={}
steering_wheel_bit5_data={}
steering_wheel_bit6_data={}
gas_pedal=[]
brake_pedal=[]
steering_wheel_bit5=[]
steering_wheel_bit6=[]
i=0
#Read data from the device as long as it is connected
while(dev!= None):
try:
#Read data
data = dev.read(ep.bEndpointAddress, ep.wMaxPacketSize,
timeout=1000)
gas_pedal.append(data[6])
gas_pedal_data['gas_pedal']=gas_pedal
scipy.io.savemat('test.mat',gas_pedal_data)
brake_pedal.append(data[7])
brake_pedal_data['brake_pedal']=brake_pedal
scipy.io.savemat('test.mat',brake_pedal_data)
steering_wheel_bit5.append(data[4])
steering_wheel_bit5_data['steering_wheel_bit5']=steering_wheel_bit5
scipy.io.savemat('test.mat',steering_wheel_bit5_data)
steering_wheel_bit6.append(data[5])
steering_wheel_bit6_data['steering_wheel_bit6']=steering_wheel_bit6
scipy.io.savemat('test.mat',steering_wheel_bit6_data)
except usb.core.USBError as e:
print("Error readin data: %s" %str(e))
time.sleep(5)
continue
You have a few options.
You can poll from within Matlab for the presence of a file, then read in the new data when available
You can open a pipe to perform inter-process communication between python and matlab (also requires polling from the matlab side). See here for code.
You can use a local UDP or TCP socket for communication. Either by using PNET (which will still require polling), or the matlab Instrument Control Toolbox (which allows you to configure a callback function).
Since matlab is single-threaded, your model will have to be designed with the provision of new data in mind. You will need to explicitly trigger the model to re-evaluate when new data is provided.