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TypeError: str, bytes or bytearray expected, not int [duplicate]

I'm trying to create a simple server to client based chat program and the issue is that when I try to execute c.sendto(data,client) this error appears saying that Client is an int but it's a tuple containing the port number and the address. I'm I supposed to convert the tuple to bytes so I can send the message to the clients?
Server Script
import socket
clients = []
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind(("127.0.0.1",7999))
s.listen()
print("Waiting for connection")
c, addr = s.accept()
while True:
data , addr = c.recvfrom(1024)
print(data)
if addr not in clients:
clients.append(addr)
print(clients[0])
if data:
for client in clients:
print(client)
c.sendto(data,client)
s.close()
Client Script
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
addr = ("127.0.0.1",7999)
s.connect(addr)
while True:
string = input(">>")
s.send(string.encode("utf-8"))
data =s.recv(1024)
s.close()
Server Output

The problem is that you're using sendto() with a connection-mode socket. I think you want c.send(data) instead.
Details:
The Python docs for sendto say "The socket should not be connected to a remote socket, since the destination socket is specified by address." Also the man page for sendto says "If sendto() is used on a connection-mode (SOCK_STREAM, SOCK_SEQPACKET) socket, the arguments dest_addr and addrlen are ignored (and the error EISCONN may be returned when they are not NULL and 0)." I somewhat suspect that this is happening and Python is misreporting the error in a confusing way.
The sockets interface and networking in general can be pretty confusing but basically sendto() is reserved for SOCK_DGRAM which is UDP/IP type internet traffic, which you can think of as sending letters or postcards to a recipient. Each one goes out with a recipient address on it and there's no guarantee on order of receipt. On the other hand, connection-mode sockets like SOCK_STREAM use TCP/IP which is a bit more like a phone call in that you make a connection for a certain duration and and each thing you send is delivered in order at each end.
Since your code seems to be designed for communication over a connection I think you just want c.send(data) and not sendto.

You must first convert the string that contains the IP address into a byte or a string of bytes and then start communicating.
According to the code below, your error will be resolved.
Make sure your code is working correctly overall.
string = '192.168.1.102'
new_string = bytearray(string,"ascii")
ip_receiver = new_string
s.sendto(text.encode(), (ip_receiver, 5252))

Python Bidirectional TCP Socket Hanging on socket.recv

Referencing this example (and the docs): https://pymotw.com/2/socket/tcp.html I am trying to achieve bidirectional communication with blocking sockets between a client and a server using TCP.
I can get one-way communication to work from client->server or server->client, but the socket remains blocked or "hangs" when trying to receive messages on both the server and client. I am using a simple algorithm(recvall), which uses recv, to consolidate the packets into the full message.
I understand the sockets remain blocked by design until all the data is sent or read(right?), but isn't that what sendall and recvall take care of? How come disabling recv on either the client or server "unblocks" it and causes it to work? And ultimately what am I doing wrong that is causing the socket to stay blocked?
Here is my code, the only fundamental difference really being the messages that are sent:
recvall(socket)(shared between client and server):
def recvall(socket):
data = ''
while True:
packet = socket.recv(16)
if not packet: break
data += packet
return data
server.py (run first):
import socket
host = 'localhost'
port = 8080
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((host, port))
s.listen(5)
while True:
(client, address) = s.accept()
print 'client connected'
try:
print recvall(client)
client.sendall('hello client')
finally:
client.close()
client.py:
import socket
s = socket.create_connection((args.ip, args.port))
try:
s.sendall('hello server')
print recvall(s)
finally:
s.close()

From my understanding (epiphany here), the main problem is that recv inside recvall is only concerned with retrieving the stream (in the same way send is only concerned with sending the stream), it has no concept of a "message" and therefore cannot know when to finish reading. It read all the bytes and did not return any additional bytes, but that is NOT a signal that the message is finished sending, there could be more bytes waiting to be sent and it would not be safe to assume otherwise.
This requires us to have an explicit indicator for when to stop reading. recv and send are only concerned with managing the stream and therefore have no concept of a message (our "unit"). This article has some great solutions to this problem. Since I am sending fixed-length messages, I opted to check that the length is as expected before finishing recv. Here is the updated version of recvall, note MSG_LENGTH must be defined and enforced in order for recvall to not block the socket.
def recvall(socket):
data = ''
while len(data) < MSG_LENGTH:
packet = socket.recv(BUFFER_SIZE)
if not packet: break
data += packet
return data
Bidirectional communication now works, the only catch being the client and server must know the length of the message they will receive, again this is not an issue in my case. This is all new to me so someone please correct me on terminology and concepts.

s.sendall doesn't work inside a thread in python

I'm trying to develop a chat program in python. I want it to have multiple clients so I'm using threading to handle this. However when I try to send the message to all connected clients, the server only sends it to the client which sent the message. I'm not sure if I'm just missing something obvious but here is the code for the server:
import socket
from thread import *
host = '192.168.0.13'
port = 1024
users = int(input("enter number of users: "))
def clienthandler(conn):
while True:
data = conn.recv(1024)
if not data:
break
print data
conn.sendall(data)
conn.close()
serversock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
serversock.bind((host, port))
serversock.listen(users)
for i in range(users):
conn, addr= serversock.accept()
print 'Connected by', addr
start_new_thread(clienthandler, (conn,))
And here is the code for the client:
import socket
host = '192.168.0.13'
port = 1024
usrname = raw_input("enter a username: ")
usrname = usrname + ": "
clientsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
clientsock.connect((host, port))
while True:
x = raw_input('You: ')
x = usrname + x
clientsock.sendall(x)
data = clientsock.recv(1024)
print data

The "all" in sendall means that it sends all of the data you asked it to send. It doesn't mean it sends it on more than one connection. Such an interface would be totally impractical. For example, what would happen if another thread was in the middle of sending something else on one of the connections? What would happen if one of the connections had a full queue?
sendall: Send data to the socket. The socket must be connected to a remote socket. The optional flags argument has the same meaning as for recv() above. Unlike send(), this method continues to send data from string until either all data has been sent or an error occurs. None is returned on success. On error, an exception is raised, and there is no way to determine how much data, if any, was successfully sent. -- 17.2. socket

You can try by pulling up the list of users, and iterating through it, and doing an individual send of the same message, though, unless you are the administrator and want to broadcast a warning, this functionality would be pretty mundane.

Send/receive Packets with TCP sockets

Recently, I managed to create sockets on my PC and my Raspberry Pi to enable communication between both devices. Currently, the client is able to automatically send messages to the server. I was wondering, if it is possible to modify the scripts to send tcp data packets instead of purely text messages, as I would very much like to control the raspberry pi using my PC in the future without having the need to ssh/etc.
I've looked at some examples, but as I don't have much experience in writing my own scripts/codes, I'm not very sure how to go about doing this. I would appreciate if someone could guide me in the right direction with explanation and some examples if possible.
Anyway here is the server/client script I'm running at the moment:
Client:
import socket
import sys
import struct
import time
#main function
if __name__ == "__main__":
if(len(sys.argv) < 2) :
print 'Usage : python client.py hostname'
sys.exit()
host = sys.argv[1]
port = 8888
#create an INET, STREAMing socket
try:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
except socket.error:
print 'Failed to create socket'
sys.exit()
print 'Socket Created'
try:
remote_ip = socket.gethostbyname( host )
s.connect((host, port))
except socket.gaierror:
print 'Hostname could not be resolved. Exiting'
sys.exit()
print 'Socket Connected to ' + host + ' on ip ' + remote_ip
#Send some data to remote server
message = "Test"
try :
#Set the whole string
while True:
s.send(message)
print 'Message sent successfully'
time.sleep(1)
print 'Sending...'
except socket.error:
#Send failed
print 'Send failed'
sys.exit()
def recv_timeout(the_socket,timeout=2):
#make socket non blocking
the_socket.setblocking(0)
#total data partwise in an array
total_data=[];
data='';
#beginning time
begin=time.time()
while 1:
#if you got some data, then break after timeout
if total_data and time.time()-begin > timeout:
break
#if you got no data at all, wait a little longer, twice the timeout
elif time.time()-begin > timeout*2:
break
#recv something
try:
data = the_socket.recv(8192)
if data:
total_data.append(data)
#change the beginning time for measurement
begin=time.time()
else:
#sleep for sometime to indicate a gap
time.sleep(0.1)
except:
pass
#join all parts to make final string
return ''.join(total_data)
#get reply and print
print recv_timeout(s)
s.close()
Server:
import socket
import sys
from thread import *
HOST = '' # Symbolic name meaning all available interfaces
PORT = 8888
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print 'Socket created'
try:
s.bind((HOST, PORT))
except socket.error , msg:
print 'Bind failed. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
sys.exit()
print 'Socket bind complete'
s.listen(10)
print 'Socket now listening'
#Function for handling connections
def clientthread(conn):
#Sending message to connected client
conn.send('Welcome to the server. Receving Data...\n') #send only takes string
#infinite loop so that function do not terminate and thread do not end.
while True:
#Receiving from client
data = conn.recv(1024)
reply = 'Message Received at the server!\n'
print data
if not data:
break
conn.sendall(reply)
conn.close()
#now keep talking with the client
while 1:
#wait to accept a connection
conn, addr = s.accept()
print 'Connected with ' + addr[0] + ':' + str(addr[1])
#start new thread
start_new_thread(clientthread ,(conn,))
s.close()

socket.socket(socket.AF_INET, socket.SOCK_STREAM) already creates a connection that provides a reliable stream of bytes between two machines. This uses TCP, which is on top of IP and Ethernet. The latter two are package-based, while TCP creates a stream of continuous bytes on top of it. It also adds some error checking and error correction, so it is pretty reliable.
I honestly don't understand what you want to achieve with what you call "send packets". What you don't want to do is to create an implementation of TCP yourself, as that's a non-trivial task, so sending RAW packets is out. In general, even using TCP is already relatively low-level and should be avoided unless really necessary.
Using e.g. ZeroMQ you get a message-based interface that does all the transmission for you. It does so on top of TCP (or other transports) and adds more error correction for e.g. disconnects. There, you also have something like "packets", but those are independent of how many TCP or IP packets were required to send it underneath. If you don't want to implement a specific protocol, I'd suggest you use this framework instead of lowlevel TCP sockets.
Another simple alternative is to use HTTP, for which there is also existing code in Python. The downside is that it is always one side that initiates some communication and the other side only replies. If you want some kind of active notification, you either have to poll or use hacks like delaying an answer.

You are already sending data packets - those packets juts happen to contain text data at the moment. Try looking into pickle in the standard libraries and into pyro.

How to tell if a connection is dead in python

I want my python application to be able to tell when the socket on the other side has been dropped. Is there a method for this?

Short answer:
use a non-blocking recv(), or a blocking recv() / select() with a very
short timeout.
Long answer:
The way to handle socket connections is to read or write as you need to, and be prepared to handle connection errors.
TCP distinguishes between 3 forms of "dropping" a connection: timeout, reset, close.
Of these, the timeout can not really be detected, TCP might only tell you the time has not expired yet. But even if it told you that, the time might still expire right after.
Also remember that using shutdown() either you or your peer (the other end of the connection) may close only the incoming byte stream, and keep the outgoing byte stream running, or close the outgoing stream and keep the incoming one running.
So strictly speaking, you want to check if the read stream is closed, or if the write stream is closed, or if both are closed.
Even if the connection was "dropped", you should still be able to read any data that is still in the network buffer. Only after the buffer is empty will you receive a disconnect from recv().
Checking if the connection was dropped is like asking "what will I receive after reading all data that is currently buffered ?" To find that out, you just have to read all data that is currently bufferred.
I can see how "reading all buffered data", to get to the end of it, might be a problem for some people, that still think of recv() as a blocking function. With a blocking recv(), "checking" for a read when the buffer is already empty will block, which defeats the purpose of "checking".
In my opinion any function that is documented to potentially block the entire process indefinitely is a design flaw, but I guess it is still there for historical reasons, from when using a socket just like a regular file descriptor was a cool idea.
What you can do is:
set the socket to non-blocking mode, but than you get a system-depended error to indicate the receive buffer is empty, or the send buffer is full
stick to blocking mode but set a very short socket timeout. This will allow you to "ping" or "check" the socket with recv(), pretty much what you want to do
use select() call or asyncore module with a very short timeout. Error reporting is still system-specific.
For the write part of the problem, keeping the read buffers empty pretty much covers it. You will discover a connection "dropped" after a non-blocking read attempt, and you may choose to stop sending anything after a read returns a closed channel.
I guess the only way to be sure your sent data has reached the other end (and is not still in the send buffer) is either:
receive a proper response on the same socket for the exact message that you sent. Basically you are using the higher level protocol to provide confirmation.
perform a successful shutdow() and close() on the socket
The python socket howto says send() will return 0 bytes written if channel is closed. You may use a non-blocking or a timeout socket.send() and if it returns 0 you can no longer send data on that socket. But if it returns non-zero, you have already sent something, good luck with that :)
Also here I have not considered OOB (out-of-band) socket data here as a means to approach your problem, but I think OOB was not what you meant.

It depends on what you mean by "dropped". For TCP sockets, if the other end closes the connection either through
close() or the process terminating, you'll find out by reading an end of file, or getting a read error, usually the errno being set to whatever 'connection reset by peer' is by your operating system. For python, you'll read a zero length string, or a socket.error will be thrown when you try to read or write from the socket.

From the link Jweede posted:
exception socket.timeout:
This exception is raised when a timeout occurs on a socket
which has had timeouts enabled via a prior call to settimeout().
The accompanying value is a string whose value is currently
always “timed out”.
Here are the demo server and client programs for the socket module from the python docs
# 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.send(data)
conn.close()
And the 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.send('Hello, world')
data = s.recv(1024)
s.close()
print 'Received', repr(data)
On the docs example page I pulled these from, there are more complex examples that employ this idea, but here is the simple answer:
Assuming you're writing the client program, just put all your code that uses the socket when it is at risk of being dropped, inside a try block...
try:
s.connect((HOST, PORT))
s.send("Hello, World!")
...
except socket.timeout:
# whatever you need to do when the connection is dropped

If I'm not mistaken this is usually handled via a timeout.

I translated the code sample in this blog post into Python: How to detect when the client closes the connection?, and it works well for me:
from ctypes import (
CDLL, c_int, POINTER, Structure, c_void_p, c_size_t,
c_short, c_ssize_t, c_char, ARRAY
)
__all__ = 'is_remote_alive',
class pollfd(Structure):
_fields_ = (
('fd', c_int),
('events', c_short),
('revents', c_short),
)
MSG_DONTWAIT = 0x40
MSG_PEEK = 0x02
EPOLLIN = 0x001
EPOLLPRI = 0x002
EPOLLRDNORM = 0x040
libc = CDLL('libc.so.6')
recv = libc.recv
recv.restype = c_ssize_t
recv.argtypes = c_int, c_void_p, c_size_t, c_int
poll = libc.poll
poll.restype = c_int
poll.argtypes = POINTER(pollfd), c_int, c_int
class IsRemoteAlive: # not needed, only for debugging
def __init__(self, alive, msg):
self.alive = alive
self.msg = msg
def __str__(self):
return self.msg
def __repr__(self):
return 'IsRemoteAlive(%r,%r)' % (self.alive, self.msg)
def __bool__(self):
return self.alive
def is_remote_alive(fd):
fileno = getattr(fd, 'fileno', None)
if fileno is not None:
if hasattr(fileno, '__call__'):
fd = fileno()
else:
fd = fileno
p = pollfd(fd=fd, events=EPOLLIN|EPOLLPRI|EPOLLRDNORM, revents=0)
result = poll(p, 1, 0)
if not result:
return IsRemoteAlive(True, 'empty')
buf = ARRAY(c_char, 1)()
result = recv(fd, buf, len(buf), MSG_DONTWAIT|MSG_PEEK)
if result > 0:
return IsRemoteAlive(True, 'readable')
elif result == 0:
return IsRemoteAlive(False, 'closed')
else:
return IsRemoteAlive(False, 'errored')

Trying to improve on #kay response. I made a more pythonic version
(Note that it was not yet tested in a "real-life" environment, and only on Linux)
This detects if the remote side closed the connection, without actually consuming the data:
import socket
import errno
def remote_connection_closed(sock: socket.socket) -> bool:
"""
Returns True if the remote side did close the connection
"""
try:
buf = sock.recv(1, socket.MSG_PEEK | socket.MSG_DONTWAIT)
if buf == b'':
return True
except BlockingIOError as exc:
if exc.errno != errno.EAGAIN:
# Raise on unknown exception
raise
return False
Here is a simple example from an asyncio echo server:
import asyncio
async def handle_echo(reader, writer):
addr = writer.get_extra_info('peername')
sock = writer.get_extra_info('socket')
print(f'New client: {addr!r}')
# Initial of client command
data = await reader.read(100)
message = data.decode()
print(f"Received {message!r} from {addr!r}")
# Simulate a long async process
for _ in range(10):
if remote_connection_closed(sock):
print('Remote side closed early')
return
await asyncio.sleep(1)
# Write the initial message back
print(f"Send: {message!r}")
writer.write(data)
await writer.drain()
writer.close()
async def main():
server = await asyncio.start_server(
handle_echo, '127.0.0.1', 8888)
addrs = ', '.join(str(sock.getsockname()) for sock in server.sockets)
print(f'Serving on {addrs}')
async with server:
await server.serve_forever()
if __name__ == '__main__':
asyncio.run(main())