I'm writing a simple client server app in python, where the client is listening every type of data entering in the specific port, and I want to when receiving a data flow, send back to the connected client (which have a dinamic ip) a string, in this case "001". But when I try to send the message, it fails!
#!/usr/bin/env python
import socket
TCP_IP = '192.168.1.115'
TCP_PORT = 55001
BUFFER_SIZE = 1024
MESSAGE = '01'
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((TCP_IP, TCP_PORT))
s.listen(1)
conn, addr = s.accept()
print ('Connection address:', addr)
while 1:
data = conn.recv(BUFFER_SIZE)
if not data: break
print ('received data:', data)
conn.send(data) # echo
print ('Sending data to client...')
addr change every connection .. i cannot manage this!
s.connect((addr, TCP_PORT))
s.send(MESSAGE)
data = s.recv(BUFFER_SIZE)
s.close()
(Connected stream) sockets are bidirectional, so there's no need to call connect to get a connection to the client—you already have one.
But you want to know why your code fails. And there are at least three problems with it.
First, after you call listen or connect on a socket, you can't call connect again; you will get an exception (EISCONN on POSIX, something equivalent on Windows). You will have to create a new socket.
Second, is client actually binded and listening for a connection on the same port as the server? If not, your connect can't work. If so, the bind will fail if the client and server are on the same machine.
Third, the addr you get back from accept is a (host, port) pair, not just a host. So, as written, you're trying to connect((('192.168.1.115', 12345), 55001)), which obviously isn't going to work.
You are trying to reply to the client using the server listening socket (s). This is only possible in UDP Servers. Since this is a TCP Server you have to use the conn which is crated using s.accept() to communication with remote client.
Related
I'm trying to make a console chat app in python using socket library.
Whenever I send a message to the server, the server code crashes with the following message:
OSError: [WinError 10057] A request to send or receive data was disallowed because the socket is not connected and (when sending on a datagram socket using a sendto call) no address was supplied
Server code
import socket
HOST = socket.gethostbyname(socket.gethostname()) # get the ip address of PC
PORT = 5050
ADDRESS = (HOST, PORT)
socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
socket.bind(ADDRESS)
while True:
socket.listen()
conn, addr = socket.accept()
print(f"Connected by {addr}")
while True:
data = conn.recv(64)
print(data.decode('utf-8'))
socket.send(data)
Client code
import socket
HOST = socket.gethostbyname(socket.gethostname()) # get the ip address of PC
PORT = 5050
ADDRESS = (HOST, PORT)
socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
socket.connect(ADDRESS)
while True:
msg = input("Enter your message")
socket.send(msg.encode('utf-8'))
data = socket.recv(64)
print(data.decode('utf-8'))
What I am trying to achieve is whenever I send a message to the server, the client script should print the sent message. How can I fix that?
You're attempting to send data to your own server socket. You instead want to send to the client that you accepted.
socket.send(data)
Should be:
conn.send(data)
If you think about it, if you had multiple clients, how would you send data to a specific client? By using the socket that accept gave you.
As a side note, you probably don't want to import the module as socket, and also call your variable socket. It's fine here, but if you were to make a more complicated project, you may accidentally refer to the object when you meant to refer to the module. I'd rename the socket object to sock or server_socket to avoid shadowing.
I want to send some simple information, like an int or a string, between two Python programs. I thought of doing it by having the programs read and write from a single-line file. But that doesn't seem to work, since one file seems to block the file. Especially since I want to check for updates every 1/12 of a second or so.
If it did work, my idea use case would be for one program to send a message with
with open('input.py','w') as file:
file.write('hello')
and receive it with
with open('input.py','r') as file:
print(file.read())
I've been looking into how to do it with sockets, but every 'simple' tutorial seems to be targeted some much more complex use case. So how do I do what I need to do in a way that'll actually work?
The best route to go is to use the socket library. This creates a client-server connection, where you can send strings between programs from there.
server.py:
import socket
s = socket.socket()
print "Socket successfully created"
port = 12345 # Reserve a port on your computer...in our case it is 12345, but it can be anything
s.bind(('', port))
print "Socket binded to %s" %(port)
s.listen(5) # Put the socket into listening mode
print "Socket is listening"
while True:
c, addr = s.accept() # Establish connection with client
print 'Got connection from', addr
c.send('Thank you for connecting') # Send a message to the client
c.close()
client.py:
import socket
s = socket.socket()
port = 12345 # Define the port on which you want to connect
s.connect(('127.0.0.1', port)) # Connect to the server on local computer
print s.recv(1024) # Receive data from the server
s.close()
From the terminal/shell:
# start the server:
$ python server.py
Socket successfully created
Socket binded to 12345
Socket is listening
Got connection from ('127.0.0.1', 52617)
# start the client:
$ python client.py
Thank you for connecting
As you can see, the client was able to receive the string "Thank you for connecting" by the server, thanks to the send() and recv() methods from the socket library.
def send_Button():
try:
myMsg = "ME: " + text.get()
msg = text.get()
conn.send(msg) ###
textBox.insert(END, myMsg + "\n")
textEntry.delete(0, END)
textBox.yview_pickplace("end")
except NameError:
myMsg = "ME: " + text.get()
msg = text.get()
conn.send(msg) ###
textBox.insert(END, myMsg + "\n")
textEntry.delete(0, END)
textBox.yview_pickplace("end")
This program uses the tkinter module with socket in python2.7. My program allows for you to either connect to a server to chat with or host a server for others to connect to you, but whenever I try and test it out then the lines with the '###' on always bring up an error and it doesn't work, the error which comes up is: "NameError: global name 'conn' is not defined" OR "error: [Errno 10057] A request to send or receive data was disallowed because the socket is not connected and (when sending on a datagram socket using a sendto call) no address was supplied".
Any help please?
I think that you are trying to get the program to act as a Client or as a Server just changing s.send() to conn.send() saddly it isn't that simple.
Socket Initializzation
The socket have to be initialized before sending or receiving data.
For a client usually it's something like this.
send_socket = socket.socket(socket.AF_INET,socket.SOCK_STREAM) # Create the socket
send_socket.connect((serverIp, serverPort)) # Connect to the server
send_socket.send(data) # Send the data to the server
And like this for a Server:
listen_socket = socket.socket(socket.AF_INET,socket.SOCK_STREAM) # Create the socket
listen_socket.bind(("0.0.0.0", port)) # Set the socket to accept client from every interface on the port port
listen_socket.listen(1) # Put the server on listen on the port setted before
accept_socket, addr = self.listen_socket.accept() # when a client connect return the socket to talk with it
data = self.accept_socket.recv(buffer_size) # Receive data form the client of max size buffer_size
Docs examples
From your question I guess that with s.send() and conn.send() you are talking about
this example from the python 2.7 socket docs
Here are four minimal example programs using the TCP/IP protocol: a server that echoes all data that it receives back (servicing only one client), and a client using it. Note that a server must perform the sequence socket(), bind(), listen(), accept() (possibly repeating the accept() to service more than one client), while a client only needs the sequence socket(), connect(). Also note that the server does not sendall()/recv() on the socket it is listening on but on the new socket returned by accept().
Client
Echo client program
import socket
HOST = 'daring.cwi.nl' # The remote host
PORT = 50007 # The same port as used by the server
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST, PORT))
s.sendall('Hello, world')
data = s.recv(1024)
s.close()
print 'Received', repr(data)
the client is pretty stright forward, it create the socket s and then after using s.connect() it just send data through it.
Server
The server one is where there there are both s and conn
Echo server program
import socket
HOST = '' # Symbolic name meaning all available interfaces
PORT = 50007 # Arbitrary non-privileged port
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((HOST, PORT))
s.listen(1)
conn, addr = s.accept()
print 'Connected by', addr
while 1:
data = conn.recv(1024)
if not data:
break
conn.sendall(data)
conn.close()
in this one first of all we create a socket s on which the server will listen and then using s.accept() it will wait till a client connect to the server and then return the conn which is the socket of the connected client.
So to receive or send data to the client you have to use conn.
Notes
As said in the documentation in these two example the server accept only one client. So if you want to deal with multiple clients you have to repeat the accept step and possibly generate a new Thread for each client so that other clients don't have to wait for each others.
I am trying to send UDP video packets using sockets in Python.
The Server IP address is :192.168.67.14
The Client IP address is 192.168.67.42
The Client and Server can ping each other. Below is the code used for establishing the socket:
Server Side:
import urllib, time, os, m3u8
from socket import *
# Socket initialization
s = socket(AF_INET, SOCK_DGRAM)
host = "192.168.67.42"
port = 5000
buf = 1024
addr = (host, port)
s.connect((host, port))
ts_filenames = []
while True:
playlist = "https://sevenwestmedia01-i.akamaihd.net/hls/live/224853/TEST1/master_lowl.m3u8"
m3u8_obj = m3u8.load(playlist)
ts_segments = m3u8_obj.__dict__.values()[6]
ts_segments_str = str(m3u8_obj.segments)
for line in ts_segments_str.splitlines():
if "https://" in line:
ts_id = line[-20:]
if ts_id not in ts_filenames:
print ts_id
ts_filenames.append(ts_id)
try:
ts_segment = urllib.URLopener()
ts_segment.retrieve(line, ts_id)
except:
pass
f = open(ts_id, "rb")
data = f.read(buf)
while (data):
if (s.sendto(data, addr)):
print "sending ..."
data = f.read(buf)
Client Side
import socket
s = socket.socket()
host = '192.168.67.14'
port = 5000
s.connect((host,port))
print s.recv(1024)
s.close
Exception I get:
Traceback (most recent call last): File "client.py", line 7, in
s.connect((host,port)) File "/usr/lib/python2.7/socket.py", line 228, in meth
return getattr(self._sock,name)(*args) socket.error: [Errno 111] Connection refused
I spent some time looking into this discussion but I still not sure what to modify. Any suggestions please ?
You have multiple problems here. First, by using connect on the server end, you're telling the operating system that you will only be communicating with IP address "192.168.67.42" port 5000. That is probably not what you intended. (A server usually talks to whatever client wants to talk to it.)
Second, by not specifying SOCK_DGRAM in your client, you're getting the default socket type, which is SOCK_STREAM. That means your client is trying to connect to your server on TCP port 80 -- not UDP port 80 (the two namespaces are totally separate).
For a UDP "session", both sides need an IP address and a port number. If you do not bind a port specifically, the operating system will choose one for you quasi-randomly. In order to link up client and server, they must agree on at least one of those.
So a typical UDP server will bind to a well-known port (presumably you intended 5000 for that purpose). Then the client can connect to the server at that port. The code would look something like this (sans error handling):
Server side:
# Create socket
s = socket(AF_INET, SOCK_DGRAM)
# Bind to our well known port (leave address unspecified
# allowing us to receive on any local network address)
s.bind(('', 5000))
# Receive from client (so we know the client's address/port)
buffer, client_addr = s.recvfrom(1024)
# Now we can send to the client
s.sendto(some_buffer, client_addr)
The client is close to what you have, but you should send some data from the client to the server first so that the server knows your address:
s = socket(AF_INET, SOCK_DGRAM)
# Create connection to server (the OS will automatically
# bind a port for the client)
s.connect((host, port))
# Send dummy data to server so it knows our address/port
s.send(b'foo')
buffer = s.recv(1024)
Note that because you have used connect on the client side, you've permanently specified your peer's address and don't need to use recvfrom and sendto.
On the client side, this is wrong:
s = socket.socket()
for receiving UDP packets, you need to create a UDP socket, same as you did on the server side:
s = socket(AF_INET, SOCK_DGRAM)
Also, if you want your client to be able to receive UDP packets you will need to bind() it to port 5000 (connect() is neither necessary nor sufficient for that).
let's say I have a multi-client server socket and a client socket in python.
Server: (You don't have to read all of the server's code, just know it's a multi-client server.
import socket, select
CONNECTION_LIST = [] # list of socket clients
RECV_BUFFER = 4096 # Advisable to keep it as an exponent of 2
PORT = 5000
server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
# this has no effect, why ?
RealServerIP = ? # I want to have a real server ip which would let me connect to the server from any computer around the globe...
server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server_socket.bind((RealServerIP, PORT))
server_socket.listen(10)
# Add server socket to the list of readable connections
CONNECTION_LIST.append(server_socket)
print "Chat server started on port " + str(PORT)
while 1:
# Get the list sockets which are ready to be read through select
read_sockets,write_sockets,error_sockets = select.select(CONNECTION_LIST,[],[])
for sock in read_sockets:
#New connection
if sock == server_socket:
# Handle the case in which there is a new connection recieved through server_socket
sockfd, addr = server_socket.accept()
CONNECTION_LIST.append(sockfd)
print "Client (%s, %s) connected" % addr
#Some incoming message from a client
else:
# Data recieved from client, process it
try:
#In Windows, sometimes when a TCP program closes abruptly,
# a "Connection reset by peer" exception will be thrown
data = sock.recv(RECV_BUFFER)
# echo back the client message
if data:
sock.send(data)
# client disconnected, so remove from socket list
except:
broadcast_data(sock, "Client (%s, %s) is offline" % addr)
print "Client (%s, %s) is offline" % addr
sock.close()
CONNECTION_LIST.remove(sock)
continue
server_socket.close()
(example from http://www.binarytides.com/code-chat-application-server-client-sockets-python/).
And 3 clients which are the most simple clients you can imagine to yourself:
import socket # imports module named 'socket'
RealServerIP = ? # I need your help here.... read the continuation
my_socket = socket.socket() # creates new socket named 'my_socket'
my_socket.connect((RealServerIP, 5000)) # connects to the server
my_socket.send(str) # sends string to the server
data = my_socket.recv(1024)
print data # prints data
my_socket.close()
I wanted to check whether my server can comunicate with those 3 clients at the same time. So I want to make my server as a public server like a web-server of Facebook, etc.
So any computer around the world could connect to it.
So, I tried to figure out how would I store my python server socket online with a specific IP and PORT which has nothing to do with my localhost, I want it to be real! Like any chat/web server you know..
If you mean the IP which the user connect with it to the internet, I don't think there is a way to get it by socket module, But i got a way to do the same thing using requests module if this may help.
import requests
def get_ip():
url = 'https://www.cmyip.com'
user_ip = requests.get(url).content.decode("utf-8").split("My IP Address is ")[1].split(" <a class=")[0]
return user_ip
I hope this help.
Note: This was tested on python 3.4.3 and it is working fine. I don't know about 2.X versions.