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How to incorporate the IP address of a device into a Python script if the address changes

I have a Python script which retrieves the measured data from a smart plug so that I can visualize it on my Rasbperry Pi.
This command gets the data
send_hs_command("192.168.1.26", 9999, b'{"emeter":{"get_realtime":{}}}')
and this is the define
def send_hs_command(address, port, cmd):
data = b""
tcp_sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
try:
tcp_sock.connect((address, port))
tcp_sock.send(encrypt(cmd))
data = tcp_sock.recv(2048)
except socket.error:
print(time.asctime( time.localtime(time.time()) ), "Socket closed.", file=sys.stderr)
finally:
tcp_sock.close()
return data
My problem is that if I take the Smart Plug somewhere else, it will have
a new IP-Address, which means I have to keep rewriting it on my Python script. This is not an option for me. What would be the simplest solution? Thanks

I don't have a Pi to run this on.
If the IP address of the target(Smart Plug) is variable, can you not use a pre-determined host-name(located in '/etc/hostname') instead?
the socket library provides a few handy functions;
You can first use
gethostbyaddr to get the host-name if you don't have the host-name information already.
Then from that point onward you can use the known host-name and use
create_connection to establish connections.
However, if you want to use something more dynamic; I'd suggest using the MAC address as the key.
Please be advised that running scapy which perhaps depends on tcpdump on Raspberry Pi might be CPU exhaustive.
Please take a look at the following snippet:
import socket
import time
import sys
from scapy.all import *
def send_hs_command(address, port, cmd):
data = b""
tcp_sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
try:
tcp_sock.connect((address, port))
tcp_sock.send(encrypt(cmd))
data = tcp_sock.recv(2048)
except socket.error:
print(time.asctime( time.localtime(time.time()) ), "Socket closed.", file=sys.stderr)
finally:
tcp_sock.close()
print(data)
return data
def get_ip_from_mac():
# Match ARP requests
packet_list = sniff(filter="arp", count=10) # increase number of arp counts
for i in packet_list:
# Show all ARP requests
# print(i[Ether].src, "is broadcasting IP", i[ARP].psrc)
if (i[ARP].hwsrc == '00:0c:29:b6:f4:be'): # target MAC address
return (True, i[ARP].psrc)
return (False, '')
def main():
result = get_ip_from_mac()
if result[0] == True:
print("Succeeded to reach server")
send_hs_command(result[1], 22, b'{"emeter":{"get_realtime":{}}}')
else:
# logic to retry or graciously fail
print("Failed to reach server")
if __name__== "__main__":
main()

python3 - broken pipe error when using socket.send()

I am programming a client-server instant message program. I created a similar program in Python 2, and am trying to program it in Python 3. The problem is when the server takes the message and tries to send it to the other client, it gives me "[Errno 32] Broken Pipe" and exits.
I have done some research, and found that this occurs when the client disconnects, so I did some more testing but could not find when the client disconnects. (I am using Ubuntu 14.04 and Python 3.4)
Here is the server code:
import socket, select, sys
def broadcast(sock, messaged):
for socket in connection_list:
if socket != s and socket != sock:
# Here is where it gives me the broken pipe error
try:
s.send(messaged.encode("utf-8"))
except BrokenPipeError as e:
print(e)
sys.exit()
connection_list = []
host = ''
port = 5558
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind((host,port))
s.listen(5)
connection_list.append(s)
read_sockets,write_sockets,error_sockets = select.select(connection_list,[],[])
while True:
for sock in read_sockets:
if sock == s:
conn, addr = s.accept()
connection_list.append(conn)
client = "Client (%s,%s) connected" % addr
print(client)
broadcast(sock,client)
else:
try:
data = sock.recv(2048)
decodeddata = data.decode("utf-8")
if data:
broadcast(sock, decodeddata)
except:
offline = "Client " + addr + "is offline"
broadcast(sock, offline)
print(offline)
connection_list.remove(sock)
sock.close()
continue
And the client code:
import socket, select, string, sys, time
def prompt(data) :
print("<You> " + data)
def Person(data) :
print("<Receiver> " + data)
if __name__ == "__main__":
host = "localhost"
port = 5558
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.settimeout(2)
try:
s.connect((host,port))
except:
print('Unable to connect')
sys.exit()
print('Connected.')
socket_list = [s]
read_sockets,write_sockets,error_sockets = select.select(socket_list,[],[])
while 1:
for sock in read_sockets:
if sock == s:
try:
time.sleep(1)
data = sock.recv(1024)
Person(data.decode("utf-8"))
except:
msg = input("Send a message: ")
try:
s.send(str.encode(msg))
except:
print("Server is offline")
sys.exit()
else:
print("Server is offline")
sys.exit()

There are two problems that you have to fix to make this work.
First, on both the client side and the server side, you have to put the select inside the loop, not outside. Otherwise, if there was something to read before you got to the loop, you'll recv over and over, and if there wasn't, you'll never recv. Once you fix this, you can get rid of the time.sleep(1). (You should never need a sleep to solve a problem like this; at best it masks the problem, and usually introduces new ones.)
Meanwhile, on the server side, inside broadcast, you're doing s.send. But s is your listener socket, not a connected client socket. You want socket.send here, because socket is each socket in connection_list.
There are a number of unrelated problems in your code as well. For example:
I'm not sure what the except: in the client is supposed to be catching. What it mainly seems to catch is that, about 50% of the time, hitting ^C to end the program triggers the send prompt. But of course, like any bare except:, it also masks any other problems with your code.
There's no way to send any data back and forth other than the "connected" message except for that except: clause.
addr is a tuple of host and port, so when someone goes offline, the server raises a TypeError from trying to format the offline message.
addr is always the last client who connected, not the one who's disconnecting.
You're not setting your sockets to nonblocking mode.
You're not checking for EOF on the recv. This means that you don't actually detect that a client has gone offline until you get an error. Which normally happens only after you try to send them a message (e.g., because someone else has connected or disconnected).

Problems with a chat program written in Python and PyGTK

I am new to python and I am currently working on a chat room program in Python (still in progress...). I have also made a GUI for my program. Initially, I made two py files, one for the GUI and one for the chatting function. They both worked perfectly when separated. After, I combined the two files. I faced the following two problems:
One of my threads (target = loadMsg) is used to wait for the host's msg and print it out on the screen. The problem is that it delays for one msg every time. For example, I sent a "1" to the host and the host should return a "1" immediately. But, the "1" I received didn't appear on my screen. Then I send a "2" to the host and the host should reply a "2" immediately. Then, my screen shows a "1" but the "2" is still missing until the host reply a "3" to me, after I send a "3" to the host. Where is the problem?
This is a technical problem. I was testing the stability of the chat room and I found that about 10% of my msg disappeared during the transmission and this situation occurs randomly. How can I fix such a problem?
Sorry for my poor English. I hope someone can help me with it.T_T
Here is my code for your reference:
---Client
import pygtk,gtk
import logging
from threading import *
import socket
DEBUG = 1
HOST = ''
PORT = 8018
TIMEOUT = 5
BUF_SIZE = 1024
class Base():
def reload(self):
try:
buf = self.sock.recv(BUF_SIZE)
print buf
self.addMsg(buf)
except:
pass
def reload_butt(self,widget):
try:
self.thread = Thread(target=self.reload)
self.thread.start()
except:
pass
def loadMsg(self):
try:
while True :
buf = self.sock.recv(BUF_SIZE)
print buf
self.addMsg(buf)
except:
self.sock.close()
def sendMsg(self,widget):
if DEBUG : print "Send Msg"
if self.entry.get_text() : self.sock.send(self.entry.get_text())
self.entry.set_text("")
def addMsg(self,string):
if DEBUG : print "Try to add Msg"
if self.entry.get_text() :
iter = self.buffer1.get_iter_at_offset(-1)
self.buffer1.insert(iter,("\n Username: "+string))
self.entry.set_text("")
self.adj = self.scrolled_window.get_vadjustment()
self.adj.set_value( self.adj.upper - self.adj.page_size )
if DEBUG : print "Add msg ok"
def destroy(self,widget):
if DEBUG : print "Destroy function called"
self.sock.close()
gtk.main_quit()
def __init__(self,sock):
if DEBUG : print "Initializing..."
self.sock = sock
self.win=gtk.Window()
self.win.connect("destroy",self.destroy)
self.vbox=gtk.VBox()
self.win.add(self.vbox)
self.view=gtk.TextView()
self.view.set_editable(False)
self.buffer1=self.view.get_buffer()
self.scrolled_window=gtk.ScrolledWindow()
self.scrolled_window.set_policy(gtk.POLICY_AUTOMATIC,gtk.POLICY_AUTOMATIC)
self.scrolled_window.add(self.view)
self.vbox.add(self.scrolled_window)
self.entry=gtk.Entry()
self.entry.connect("activate",self.sendMsg)
self.enter=gtk.Button("Enter")
self.enter.connect("clicked",self.sendMsg)
self.reload=gtk.Button("Reload")
self.reload.connect("clicked",self.reload_butt)
self.hbox=gtk.HBox()
self.hbox.add(self.entry)
self.hbox.pack_start(self.reload,False,False)
self.hbox.pack_start(self.enter,False,False)
self.vbox.pack_start(self.hbox,False,False)
self.win.show_all()
if DEBUG : print "Finish initializing"
def main(self):
try :
gtk.main()
except :
print "Error!!!"
def main() :
try :
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((HOST, PORT))
print ('Connecting to '+ str(HOST) +' ' + str(PORT))
base=Base(sock)
thread1=Thread(target=base.loadMsg)
thread2=Thread(target=base.main)
thread2.start()
thread1.start()
except :
print "Err0r!!!"
sock.close()
main()
---host (an echo host)
import socket
HOST = ''
PORT = 8018
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((HOST, PORT))
s.listen(5)
conn, addr = s.accept()
print 'Connected by', addr
try :
print "Start!"
while True:
data = conn.recv(1024)
print data
reply = data # echo
if not reply : break
if reply== "!q" :
conn.close()
break
conn.send(reply)
conn.close()
except :
print "Error!!!!!"
conn.close()

I would seriously recommend to use the gio library (part of glib). Using that library, you connect functions to the socket operations such as when data is available, or when data can be written to the socket. The library will call these function when necessary, and you don't need a wait loop. Which is more CPU-friendly.
http://jcoppens.com/soft/howto/gtk/chat_socket.php contains an example of communications between a C program and Python, using gio, which might be useful to you.
This way, you can start monitoring the sockets after the GUI has started, and you do not need threads to attend the communications.

create multi-thread tcp server python 3

Hello I tried to make a simple server that accept multiple clients simultaneously I'm new to python and I have a difficult to understand it....I try to change my code in multi-thread applications but without positive result...here is the code:
import socket, threading
def message():
while 1:
data = connection.recv(1024)
if not data: break
#connection.sendall(b'-- Message Received --\n')
print(data.decode('utf-8'))
connection.close()
def connection():
address = input("Insert server ip")
port = 44444
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((address, port))
s.listen(1)
print("Server started! Waiting for connections...")
def accept connection():
connection, address = s.accept()
print('Client connected with address:', address)
t=thread.Threading(target=message,args=(connection))
t.run()
I know that there are many errors but I'm new in python sorry :(
The original non-threaded code is:
import socket
address = input("Insert server ip:")
port = 44444
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((address, port))
s.listen(1)
print("Server started! Waiting for connections...")
connection, address = s.accept()
print('Client connected with address:', address)
while 1:
data = connection.recv(1024)
if not data: break
#connection.sendall(b'-- Message Received --\n')
print(data.decode('utf-8'))
connection.close()

Your basic design is close, but you've got a whole lot of little problems making it hard to move forward.
First, you have a function name with a space in it, which isn't allowed. And you have an IndentationError because you didn't indent its contents.
Next, inside that accept_connection function, you're using threading wrong.
thread.Threading doesn't exist; you probably meant threading.Thread.
args has to be a sequence (tuple, list, etc.) of values. You probably expected (connection) to be a tuple of one value, but it's not; tuples are defined by commas, not parentheses, and what you have is just the value connection with superfluous parentheses around it. You wanted (connection,) here.
Also, calling run on a thread object just runs the thread's code in the current thread. You want to call start, which will start a new thread and call the run method on that thread.
Meanwhile, you're never actually calling this function anywhere, so of course it can't do anything. Think about where you want to call it. After creating the listener socket, you want to loop around accept, kicking off a new client thread for each accepted connection, right? So, you want to call it in a loop, either inside connection, or at the top level (in which case connection has to return s).
And finally, your accept_connection function can't access local variables from some other function; if you want it to use a socket named s, you have to pass it as a parameter.
So:
def connection():
address = input("Insert server ip")
port = 44444
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((address, port))
s.listen(1)
print("Server started! Waiting for connections...")
while True:
accept_connection(s)
def accept_connection(s):
connection, address = s.accept()
print('Client connected with address:', address)
t=thread.Threading(target=message, args=(connection,))
t.start()
As a side note, be careful with using sock.recv(1024) and assuming you're going to get the whole message that the other side sent with send(msg). You might get that, or you might get half the message, or the whole message plus half of another message the client sent later. Sockets are just streams of bytes, like files, not streams of separate messages; you need some kind of protocol to separate messages.
The simplest possible protocol is to send each message on its own line. Then you can just do socket.makefile() and for line in f:, just like you would for a real file. Of course this doesn't work if your messages can have newlines, but you can, e.g., backslash-escape them on one side and unescape them on the other.

This is a pretty old post but there's a nice way to do what you're talking about. Here's a link to an example I posted a little while back:
https://bitbucket.org/matthewwachter/tcp_threadedserver/src/master/
And the script:
from datetime import datetime
from json import loads, dumps
from pprint import pprint
import socket
from threading import Thread
class ThreadedServer(Thread):
def __init__(self, host, port, timeout=60, debug=False):
self.host = host
self.port = port
self.timeout = timeout
self.debug = debug
Thread.__init__(self)
# run by the Thread object
def run(self):
if self.debug:
print(datetime.now())
print('SERVER Starting...', '\n')
self.listen()
def listen(self):
# create an instance of socket
self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
# bind the socket to its host and port
self.sock.bind((self.host, self.port))
if self.debug:
print(datetime.now())
print('SERVER Socket Bound', self.host, self.port, '\n')
# start listening for a client
self.sock.listen(5)
if self.debug:
print(datetime.now())
print('SERVER Listening...', '\n')
while True:
# get the client object and address
client, address = self.sock.accept()
# set a timeout
client.settimeout(self.timeout)
if self.debug:
print(datetime.now())
print('CLIENT Connected:', client, '\n')
# start a thread to listen to the client
Thread(target = self.listenToClient,args = (client,address)).start()
# send the client a connection message
# res = {
# 'cmd': 'connected',
# }
# response = dumps(res)
# client.send(response.encode('utf-8'))
def listenToClient(self, client, address):
# set a buffer size ( could be 2048 or 4096 / power of 2 )
size = 1024
while True:
try:
# try to receive data from the client
data = client.recv(size).decode('utf-8')
if data:
data = loads(data.rstrip('\0'))
if self.debug:
print(datetime.now())
print('CLIENT Data Received', client)
print('Data:')
pprint(data, width=1)
print('\n')
#send a response back to the client
res = {
'cmd': data['cmd'],
'data': data['data']
}
response = dumps(res)
client.send(response.encode('utf-8'))
else:
raise error('Client disconnected')
except:
if self.debug:
print(datetime.now())
print('CLIENT Disconnected:', client, '\n')
client.close()
return False
if __name__ == "__main__":
ThreadedServer('127.0.0.1', 8008, timeout=86400, debug=True).start()

Here is some example code I have showing a threaded socket connection.
def sock_connection( sock, host ):
"Handle socket"
pass
while 1:
try:
newsock = sock.accept()
thread = Thread( target=sock_connection, args=newsock )
thread.start()
except Exception, e:
print "error on socket connection: " % e)

Python Socket Listening

All of the below mentioned is on windows machines using python 2.7
Hello,
I am currently attempting to listen on a socket for data send by a remote program. This data is then printed to the screen and user input is requested that is then returned to remote program. In testing I have been able to have the remote program send me a menu of command line programs (cmd, ipconfig, whoami, ftp) and then my program returns with a number as a selection of the menu option.
The remote program receives my response and sends the output of the selected command. ipconfig and whoami work perfectly, but cmd and ftp only returns the output of the terminal once. (I.E. I can enter one command into the FTP program and send that too the remote program before I never hear back)
The part of my code that fails is that
if ready[0]: never becomes ready a second time after the first conversation.
I know the remote program is functioning correctly as I can use netcat to act in lieu of my code and operate the cmd terminal indefinitely.
How do I go about properly implementing a python socket listener that can account for this type of connection?
My "program" in its entirety:
import socket, sys, struct, time, select
host = ''
port = 50000
connectionSevered=0
try:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
except socket.error:
print 'Failed to create socket'
sys.exit()
print '[+] Listening for connections on port '+str(port)+'.'
s.bind((host,port))
s.listen(5)
def recvall(the_socket,timeout=2):
global connectionSevered
data=''; # Data found by recv
total_data=[]; # Finally list of everything
s.setblocking(0) #make socket non blocking
begin=time.time() #beginning time
while 1:
ready = select.select([client], [], [], .2)
if time.time()-begin > timeout:
print 'Timeout reached'
#Leave loop, timer has reached its threshold
break
if ready[0]:
print 'In ready loop!'
try:
data = client.recv(4096) #attempt to fetch data
if data:
begin=time.time() #reset timeout timer
total_data.append(data)
data='';
except socket.error:
print '[+] Lost connection to client. Printing buffer...'
connectionSevered=1 # Let main loop know connection has errored
pass
time.sleep(1)
#join all parts to make final string
return ''.join(total_data)
client, address = s.accept()
print '[+] Client connected!'
while (connectionSevered==0): # While connection hasn't errored
print "connectionSevered="+str(connectionSevered) # DEBUG
recvall(s)
response = raw_input() #take user input
client.sendto(response) #send input
client.close(0)
Please let me know if you need more information, any help would be greatly appreciated, I am very new to this and eager to learn.

Playing around with this for a while finally got it working nice with a telnet session locally using python 2.7.
What it does is it sets up a thread that runs when the client connects listening for client stuff.
When the client sends a return ("\r\n" might have to change that if your interacting with a Linux system?) the message gets printed to the server, while this is happening if there is a raw input at the server side this will get sent to the client:
import socket
import threading
host = ''
port = 50000
connectionSevered=0
class client(threading.Thread):
def __init__(self, conn):
super(client, self).__init__()
self.conn = conn
self.data = ""
def run(self):
while True:
self.data = self.data + self.conn.recv(1024)
if self.data.endswith(u"\r\n"):
print self.data
self.data = ""
def send_msg(self,msg):
self.conn.send(msg)
def close(self):
self.conn.close()
try:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((host,port))
s.listen(5)
except socket.error:
print 'Failed to create socket'
sys.exit()
print '[+] Listening for connections on port: {0}'.format(port)
conn, address = s.accept()
c = client(conn)
c.start()
print '[+] Client connected: {0}'.format(address[0])
c.send_msg(u"\r\n")
print "connectionSevered:{0}".format(connectionSevered)
while (connectionSevered==0):
try:
response = raw_input()
c.send_msg(response + u"\r\n")
except:
c.close()
The above answer will not work for more than a single connection. I have updated it by adding another thread for taking connections. It it now possible to have more than a single user connect.
import socket
import threading
import sys
host = ''
port = 50000
class client(threading.Thread):
def __init__(self, conn):
super(client, self).__init__()
self.conn = conn
self.data = ""
def run(self):
while True:
self.data = self.data + self.conn.recv(1024)
if self.data.endswith(u"\r\n"):
print self.data
self.data = ""
def send_msg(self,msg):
self.conn.send(msg)
def close(self):
self.conn.close()
class connectionThread(threading.Thread):
def __init__(self, host, port):
super(connectionThread, self).__init__()
try:
self.s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.s.bind((host,port))
self.s.listen(5)
except socket.error:
print 'Failed to create socket'
sys.exit()
self.clients = []
def run(self):
while True:
conn, address = self.s.accept()
c = client(conn)
c.start()
c.send_msg(u"\r\n")
self.clients.append(c)
print '[+] Client connected: {0}'.format(address[0])
def main():
get_conns = connectionThread(host, port)
get_conns.start()
while True:
try:
response = raw_input()
for c in get_conns.clients:
c.send_msg(response + u"\r\n")
except KeyboardInterrupt:
sys.exit()
if __name__ == '__main__':
main()
Clients are not able to see what other clients say, messages from the server will be sent to all clients. I will leave that as an exercise for the reader.

If you're in Python 3 by now and still wondering about sockets, here's a basic way of using them:
server.py
import time
import socket
# creating a socket object
s = socket.socket(socket.AF_INET,
socket.SOCK_STREAM)
# get local Host machine name
host = socket.gethostname() # or just use (host == '')
port = 9999
# bind to pot
s.bind((host, port))
# Que up to 5 requests
s.listen(5)
while True:
# establish connection
clientSocket, addr = s.accept()
print("got a connection from %s" % str(addr))
currentTime = time.ctime(time.time()) + "\r\n"
clientSocket.send(currentTime.encode('ascii'))
clientSocket.close()
client.py
import socket
# creates socket object
s = socket.socket(socket.AF_INET,
socket.SOCK_STREAM)
host = socket.gethostname() # or just use (host = '')
port = 9999
s.connect((host, port))
tm = s.recv(1024) # msg can only be 1024 bytes long
s.close()
print("the time we got from the server is %s" % tm.decode('ascii'))
Run server.py first, then run client.py.
This is just send and receive the currentTime.
What's new in Python 3.4 sockets?
A major difference between python 2.7 sockets and python 3.4 sockets is the sending messages. you have to .encode() (usually using 'ascii' or blank as parameters/arguments)
and then using .decode()
For example use .encode() to send, and use .decode() to receive.
Extra info: client/server socket tutorial