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dynamically adding a resource to a python coap server with coapthon library

I am trying to build a coap server, in which I can add a new resource without the need to stop the server, recode it and restart .my server is suppossed to host two types of resources, "sensors(Sens-Me)" and "Actuators(Act-Me)" . I want that if I press the A key, a new instance of actuator should be added to the server, likewise If i Press S for Sensor .Below is my code :
from coapthon.resources.resource import Resource
from coapthon.server.coap import CoAP
class Sensor(Resource):
def __init__(self,name="Sensor",coap_server=None):
super(Sensor,self).__init__(name,coap_server,visible=True,observable=True,allow_children=True)
self.payload = "This is a new sensor"
self.resource_type = "rt1"
self.content_type = "application/json"
self.interface_type = "if1"
self.var = 0
def render_GET(self,request):
self.payload = "new sensor value ::{}".format(str(int(self.var+1)))
self.var +=1
return self
class Actuator(Resource):
def __init__(self,name="Actuator",coap_server=None):
super(Actuator,self).__init__(name,coap_server,visible=True,observable=True)
self.payload="This is an actuator"
self.resource_type="rt1"
def render_GET(self,request):
return self
class CoAPServer(CoAP):
def __init__(self, host, port, multicast=False):
CoAP.__init__(self,(host,port),multicast)
self.add_resource('sens-Me/',Sensor())
self.add_resource('act-Me/',Actuator())
print "CoAP server started on {}:{}".format(str(host),str(port))
print self.root.dump()
def main():
ip = "0.0.0.0"
port = 5683
multicast=False
server = CoAPServer(ip,port,multicast)
try:
server.listen(10)
print "executed after listen"
except KeyboardInterrupt:
server.close()
if __name__=="__main__":
main()

I am not sure what exactly do you want to do.
Is it just to replace a resource on the same route or add a new one?
Replace a resource
It is not possible according to the current coapthon version source:
https://github.com/Tanganelli/CoAPthon/blob/b6983fbf48399bc5687656be55ac5b9cce4f4718/coapthon/server/coap.py#L279
try:
res = self.root[actual_path]
except KeyError:
res = None
if res is None:
if len(paths) != i:
return False
resource.path = actual_path
self.root[actual_path] = resource
Alternatively, you can solve it in scope of request.
Say, have a registry of handlers which are used by resources and can be changed on a user input event. Well, you'll not be able to add new routes.
If you absolutely need that feature, you may request it from a developer or contribute to that project.
Add a new resource
I have extended your snippet a little bit.
I have a little experience in Python so I an not sure I've made everything properly, but it works.
There is a separate thread polling the user input and adding the same resource. Add the needed code there.
from coapthon.resources.resource import Resource
from coapthon.server.coap import CoAP
from threading import Thread
import sys
class Sensor(Resource):
def __init__(self,name="Sensor",coap_server=None):
super(Sensor,self).__init__(name,coap_server,visible=True,observable=True,allow_children=True)
self.payload = "This is a new sensor"
self.resource_type = "rt1"
self.content_type = "application/json"
self.interface_type = "if1"
self.var = 0
def render_GET(self,request):
self.payload = "new sensor value ::{}".format(str(int(self.var+1)))
self.var +=1
return self
class Actuator(Resource):
def __init__(self,name="Actuator",coap_server=None):
super(Actuator,self).__init__(name,coap_server,visible=True,observable=True)
self.payload="This is an actuator"
self.resource_type="rt1"
def render_GET(self,request):
return self
class CoAPServer(CoAP):
def __init__(self, host, port, multicast=False):
CoAP.__init__(self,(host,port),multicast)
self.add_resource('sens-Me/',Sensor())
self.add_resource('act-Me/',Actuator())
print "CoAP server started on {}:{}".format(str(host),str(port))
print self.root.dump()
def pollUserInput(server):
while 1:
user_input = raw_input("Some input please: ")
print user_input
server.add_resource('sens-Me2/', Sensor())
def main():
ip = "0.0.0.0"
port = 5683
multicast=False
server = CoAPServer(ip,port,multicast)
thread = Thread(target = pollUserInput, args=(server,))
thread.setDaemon(True)
thread.start()
try:
server.listen(10)
print "executed after listen"
except KeyboardInterrupt:
print server.root.dump()
server.close()
sys.exit()
if __name__=="__main__":
main()

Limiting file size in Twisted FTP server

I am trying to implement an FTP server using twisted that limits the size of the uploaded file. Ideally this would happen before the transfer starts, but it is not really a problem if it exits gracefully during the transfer if it is too large.
I have started from the very basic ftpserver.py and slowly been pulling in more of the underlying classes from ftp.py to get down to the innards.
Current code below, please excuse the 'hack-and-slash' style employed until I can get it working.
#!/usr/bin/python
import os
from twisted.protocols.ftp import FTPFactory, FTPShell, FTPAnonymousShell, IFTPShell
from twisted.cred.portal import Portal
from twisted.cred.checkers import AllowAnonymousAccess
from twisted.internet import reactor, defer
from twisted.python import filepath, failure
class FileConsumer1(object):
def __init__(self, fObj):
self.fObj = fObj
def registerProducer(self, producer, streaming):
self.producer = producer
assert streaming
def unregisterProducer(self):
self.producer = None
self.fObj.close()
def write(self, bytes):
size = os.fstat(self.fObj.fileno()).st_size + len(bytes)
if size > 10:
raise Exception("File too large") # WHAT GOES HERE?
self.fObj.write(bytes)
class FileWriter1(object):
def __init__(self, fObj):
self.fObj = fObj
self._receive = False
def receive(self):
assert not self._receive, "Can only call IWriteFile.receive *once* per instance"
self._receive = True
return defer.succeed(FileConsumer1(self.fObj))
def close(self):
return defer.succeed(None)
class FTPShell1(FTPShell):
def openForWriting(self, path):
p = self._path(path)
if p.isdir():
return defer.fail(IsADirectoryError(path))
try:
fObj = p.open('w')
except (IOError, OSError), e:
return errnoToFailure(e.errno, path)
except:
return defer.fail()
return defer.succeed(FileWriter1(fObj))
class FTPRealm1(object):
def __init__(self, root):
self.path = filepath.FilePath(root)
def requestAvatar(self, avatarId, mind, *interfaces):
avatar = FTPShell1(self.path)
return (IFTPShell, avatar, getattr(avatar, 'logout', lambda: None))
p = Portal(FTPRealm1('./'), [ AllowAnonymousAccess() ])
f = FTPFactory(p)
reactor.listenTCP(4021, f)
reactor.run()
clearly the check if size > 10 will be bigger, but how should a be indicating there's a problem at this point? As it stands, twisted catches that exception, but it's not very elegant. As far as I can see from examination of ftp.py there's nothing obvious I can return here. Can I pass down a deferred in some way? How should I be closing down the transfer elegantly?
Thanks,
Here's a revised version
#!/usr/bin/python
import os
from zope.interface import Interface, implements
from twisted.protocols.ftp import FTPFactory, FTPShell, FTPAnonymousShell, IFTPShell, IWriteFile , BaseFTPRealm, FTPCmdError, EXCEEDED_STORAGE_ALLOC
from twisted.cred.portal import Portal
from twisted.cred.checkers import AllowAnonymousAccess
from twisted.internet import reactor, defer, interfaces
from twisted.python import filepath
class ExceededStorageAllocError(FTPCmdError):
errorCode = EXCEEDED_STORAGE_ALLOC
class FileConsumer(object):
implements(interfaces.IConsumer)
def __init__(self):
self.data = ""
self.error = None
def registerProducer(self, producer, streaming):
self.producer = producer
assert streaming
def unregisterProducer(self):
if self.producer:
self.producer.stopProducing()
self.producer = None
def write(self, bytes):
self.data += bytes
if len(self.data) > 10:
self.unregisterProducer()
self.error = ExceededStorageAllocError()
class FileWriter(object):
implements(IWriteFile)
def __init__(self, path):
self.path = path
def receive(self):
self.consumer = FileConsumer()
return defer.succeed(self.consumer)
def close(self):
if self.consumer.error:
return defer.fail(self.consumer.error)
try:
f = self.path.open('w')
except (IOError, OSError), e:
return errnoToFailure(e.errno, path)
f.write(self.consumer.data)
return defer.succeed(None)
class FTPShell1(FTPShell):
makeDirectory = FTPAnonymousShell.makeDirectory
removeDirectory = FTPAnonymousShell.removeDirectory
def openForWriting(self, path):
p = self._path(path)
if p.isdir():
return defer.fail(IsADirectoryError(path))
return defer.succeed(FileWriter(p))
class FTPRealm1(BaseFTPRealm):
def __init__(self, root):
self.root = root
def requestAvatar(self, avatarId, mind, *interfaces):
avatar = FTPShell1(filepath.FilePath(self.root))
return (IFTPShell, avatar, getattr(avatar, 'logout', lambda: None))
p = Portal(FTPRealm1('./'), [ AllowAnonymousAccess() ])
f = FTPFactory(p)
reactor.listenTCP(4021, f)
reactor.run()
which accumulates the received data within the FileConsumer() then aborts if the file is too long. the close() method of the FileWriter() then either reports that error or writes the complete buffer to the file.
The only real issue I'm having with this is that when run, the exception is displayed on the server:
Unexpected error received during transfer:
Traceback (most recent call last):
Failure: __main__.ExceededStorageAllocError:

As a quick disclaimer, I'm very bad with Twisted's producer/consumer model, so this may not work. As always, I'm not responsible if things blow up ;)
You seem to be on the correct path so pat yourself on the back for that. I think if you call unregisterProducer when a file is too large, the file should stop consuming. You may also need to call self.producer.stopProducing(), but don't quote me on that.
def unregisterProducer(self):
self.producer.stopProducing()
self.fObj.close()
def write(self, bytes):
size = os.fstat(self.fObj.fileno()).st_size + len(bytes)
if size > 10:
self.unregisterConsumer()
# log statements would go here
# do some clean up too
self.fObj.write(bytes)
If my mental code Python interpreter is correct, this should simply just stop consuming the file. As far as what you should return to the client, you're going to have to read the RFC about FTP to figure that out.
PS
As tedious as it may seem, please use the #implementor decorators. Most times you'll be fine, but there may be instances where unexpected trace backs appear.

Python method not executed

Total noob here. I'm trying to create a python object and execute methods in an instance therein and it seems the code block I want to execute just won't run. The code block in question is run_job which when called just seems to do nothing. What am I doing wrong?
import datetime
import uuid
import paramiko
class scan_job(object):
def __init__(self, protocol, target, user_name, password, command):
self.guid = uuid.uuid1()
self.start_time = datetime.datetime.now()
self.target = target
self.command = command
self.user_name = user_name
self.password = password
self.protocol = protocol
self.result = ""
def run_job(self):
if self.protocol == 'SSH':
ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
try:
print "creating connection"
ssh.connect(self.target, self.user_name, self.password)
print "connected"
stdin, stdout, stderr = ssh.exec_command(self.command)
for line in stdout:
print '... ' + line.strip('\n')
self.result += line.strip('\n')
yield ssh
finally:
print "closing connection"
ssh.close()
print "closed"
else:
print "Unknown protocol"
def show_command(self):
print self.command
test = scan_job('SSH', '192.168.14.10', 'myuser', 'mypassword', 'uname -n')
test.show_command()
test.run_job()

Your method contains a yield statement, which makes it a generator. Generators are evaluated lazily. Consider:
>>> def gen():
... yield 10
... yield 3
... yield 42
...
>>> result = gen()
>>> next(result)
10
>>> next(result)
3
>>> next(result)
42
>>>
This is likely not what you intended to do.

Yield is a keyword that is used like return, except the function will
return a generator.
To read more about generators:
1) Understanding Generators in Python
2) What does the "yield" keyword do in Python?
3) Understanding the Yield Keyword in Python
All you need to do is, change:
yield ssh
To:
return ssh
So that, run_job will execute like a normal function, until it reaches its end, exception or return statement. However, if you want to run it without changing the yield statement. Here is how you can do it:
x = test.run_job()
x.next()

PySerial presenting strange behavior in Python 3

I have the following class (very basic) for communication with 3G modem through AT commands:
import serial
import time
class ATCommands(object):
def __init__(self, port):
self.ser = None
self.port = port
self.open()
def open(self):
self.ser = serial.Serial('/dev/'+ self.port, 115200, timeout=1)
def sendCommand(self,command):
self.ser.write(command.encode())
data = self.ser.readline().strip()
return data
def getIMEI(self):
IMEI = self.sendCommand("AT+CGSN\r")
IMEI = self.sendCommand("AT+CGSN\r")
return IMEI
def getIMEIErro(self):
IMEI = self.sendCommand("AT+CGSN\r")
return IMEI
def getIMEIErro2(self):
self.ser.write("AT+CGSN\r".encode())
data = self.ser.readline().strip()
return data
def __del__(self):
self.ser.close()
if __name__ == '__main__':
print(ATCommands('ttyUSB1').getIMEI()) #OK
print(ATCommands('ttyUSB1').getIMEIErro()) #erro
print(ATCommands('ttyUSB1').getIMEIErro2()) #erro
In the code above I have two strange things:
getIMEI() only works if I execute the statement self.sendCommand("AT+CGSN\r") twice in a row. getIMEIErro() shows that the IMEI is not returned a single command is sent.
If I run the command self.ser.readline() outside the method sendCommand() the code also does not work. getIMEIErro2() shows this error
Anyone know the reason for the errors?
PS: I'm using python 3 e pySerial 2.7

Try this
clear the buffer
put sleeps to wait the baudrate to apply the commands to the modem
always end your commands with \r\n
Something like (based of in my class in https://github.com/vhpanisa/misc pyatapi.py):
def sendCommand(self,command):
from time import sleep
while self.ser.inWaiting() > 0:
self.ser.read()
sleep(0.1)
# Maybe ascii encode not needed, just bytes convert
self.ser.write(bytes(command+"\r\n", encoding='ascii'))
sleep(0.5)
data = []
while self.ser.inWaiting() > 0:
msg = self.ser.readline().strip()
sleep(0.1) # Wait for buffer
msg = msg.replace(b"\r",b"")
msg = msg.replace(b"\n",b"")
if msg != b"":
data.append(str(msg, encoding='ascii'))
return data

Add SMTP AUTH support to Python smtpd library... can't override the method?

So, I wanted to extend the Python smtpd SMTPServer class so that it could handle SMTP AUTH connections. Seemed simple enough...
So, it looked like I could just start like this:
def smtp_EHLO(self, arg):
print 'got in arg: ', arg
# do stuff here...
But for some reason, that never gets called. The Python smtpd library calls other similar methods like this:
method = None
i = line.find(' ')
if i < 0:
command = line.upper()
arg = None
else:
command = line[:i].upper()
arg = line[i+1:].strip()
method = getattr(self, 'smtp_' + command, None)
Why won't it call my method?
After that, I thought that I could probably just override the entire found_terminator(self): method, but that doesn't seem to work either.
def found_terminator(self):
# I add this to my child class and it never gets called...
Am I doing something stupid or...? Maybe I just haven't woken up fully yet today...
import smtpd
import asyncore
class CustomSMTPServer(smtpd.SMTPServer):
def smtp_EHLO(self, arg):
print 'got in arg: ', arg
def process_message(self, peer, mailfrom, rcpttos, data):
print 'Receiving message from:', peer
print 'Message addressed from:', mailfrom
print 'Message addressed to :', rcpttos
print 'Message length :', len(data)
print 'HERE WE ARE MAN!'
return
# Implementation of base class abstract method
def found_terminator(self):
print 'THIS GOT CALLED RIGHT HERE!'
line = EMPTYSTRING.join(self.__line)
print >> DEBUGSTREAM, 'Data:', repr(line)
self.__line = []
if self.__state == self.COMMAND:
if not line:
self.push('500 Error: bad syntax')
return
method = None
i = line.find(' ')
if i < 0:
command = line.upper()
arg = None
else:
command = line[:i].upper()
arg = line[i+1:].strip()
method = getattr(self, 'smtp_' + command, None)
print 'looking for: ', command
print 'method is: ', method
if not method:
self.push('502 Error: command "%s" not implemented' % command)
return
method(arg)
return
else:
if self.__state != self.DATA:
self.push('451 Internal confusion')
return
# Remove extraneous carriage returns and de-transparency according
# to RFC 821, Section 4.5.2.
data = []
for text in line.split('\r\n'):
if text and text[0] == '.':
data.append(text[1:])
else:
data.append(text)
self.__data = NEWLINE.join(data)
status = self.__server.process_message(self.__peer,
self.__mailfrom,
self.__rcpttos,
self.__data)
self.__rcpttos = []
self.__mailfrom = None
self.__state = self.COMMAND
self.set_terminator('\r\n')
if not status:
self.push('250 Ok')
else:
self.push(status)
server = CustomSMTPServer(('127.0.0.1', 1025), None)
asyncore.loop()

You need to extend SMTPChannel -- that's where the smtp_verb methods are implemented; your extension of SMTPServer just needs to return your own subclass of the channel.

TL&DR: To add additional functionality to SMTPChannel you just need to declare a function, and then add it directly to smtpd.SMTPChannel
Explanation:
The SMTPChannel class is designed to respond to the commands that are entered by the user on the open port (typically port 25). The way it searches for which commands it can answer is based off 'Introspection' where it examines all the available attributes of the function.
Take note that the functions within SMTPChannel need to start with the "smtp_". For Example, if you wanted to respond to HELP you would create smtpd.SMTPChannel.smtp_HELP.
The Function below is from the source-code that details the introspection
class SMTPChannel(asynchat.async_chat):
method = getattr(self, 'smtp_' + command, None)
CodeThatWorks
Step 1: Declare a FUNCTION that will be called
def smtp_HELP(self,arg):
self.push("[8675309] GPT Answers to HELP")
Step 2: Add the following function to smtpd.SMTPChannel
class FakeSMTPServer(smtpd.SMTPServer):
"""A Fake smtp server"""
smtpd.SMTPChannel.smtp_HELP = smtp_HELP
Step 3: Telnet to localhost 25 and test out
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 vics-imac.fios-router.home ESMTP Sendmail 6.7.4 Sunday 17 March 2019
HELP
[8675309] GPT Answers to HELP