Develop Reference

Python client socket not receiving data from TCP server

I'm trying to build a fake money transfer program with sockets in python. Everything is working perfectly except the "name" and "amount" transfer from the server to the client. When someone clicks receive on the client interface, the server is supposed to send the client the name of the person who sent the money and the amount. The problem is that the client is not receiving the data sent from the server. When you click the "receive" button, the interface just freezes then crashes. From the debugging I've done, I'm pretty sure the server is sending the name and amount, but the client is not receiving it. I honestly have no idea why it's not working. Everything I did should work like it has numerous other times throughout the program. This one has got me stumped.
Any help would be great. Thanks! 😁
[CODE]
Server.py:
import socket
import threading
HOST = '192.168.1.6'
PORT = 9090
def client_fun(client, addr):
global transfers
print(f"{addr} just connected!")
connected = True
while connected:
msg = client.recv(1024).decode('utf-8')
if msg == "RECEIVE_CHECK":
usrn = client.recv(1024).decode('utf-8')
transfers_ = open("transfers.txt", "r")
transfers = str(transfers_.readlines())
transfers = transfers.split("+")
transfers[0] = transfers[0].replace("[", "")
transfers[0] = transfers[0].replace("'", "")
transfers.pop()
names = []
for tran in transfers:
tran_ = tran.split("-")
i = 0
while i <= len(tran):
names.append(tran_[2])
i += 1
if usrn in names:
client.send("OK".encode('utf-8'))
else:
client.send("NO".encode('utf-8'))
if usrn in names:
for tran in transfers:
tran_ = tran.split("-")
if usrn == tran_[2]:
name = str(tran_[0])
amount = str(tran_[1])
client.send(name.encode('utf-8'))
client.send(amount.encode('utf-8'))
account_file = usrn + "_" + "account.txt"
account_r = open(account_file, "r")
account_r = str(account_r.readlines())
account_r = account_r.replace(']', '')
account_r = account_r.replace('[', '')
account_r = account_r.replace("'", "")
try:
account_r = int(account_r)
except:
print("Can't Convert Str to Int!")
break
new_amount = int(tran_[1]) + account_r
account_w = open(account_file, "w")
account_w.write(str(new_amount))
account_w.close()
tran = tran + "+"
transFers_ = open("transfers.txt", "r")
transFers = str(transFers_.readlines())
transFers_.close()
transFers = transFers.replace(']', '')
transFers = transFers.replace('[', '')
transFers = transFers.replace("'", "")
transFers = transFers.replace(tran, '')
transFers_ = open("transfers.txt", 'w+')
transFers_.write(transFers)
transFers_.close()
print("Excepted!")
else:
print("Nothing Here!")
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind((HOST, PORT))
server.listen()
print("Server is listening!")
while True:
c_socket, address = server.accept()
thread = threading.Thread(target=client_fun, args=(c_socket, address))
thread.start()
Client.py:
import socket
HOST = '192.168.1.6'
PORT = 9090
socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
def receive(usrn):
socket.send("RECEIVE_CHECK".encode('utf-8'))
socket.send(usrn.encode('utf-8'))
c = socket.recv(1024).decode('utf-8')
if c == "OK":
try:
print("Trying to except....")
name = socket.recv(2000).decode('utf-8')
amount = socket.recv(2000).decode('utf-8')
print("Excepted!")
messagebox.showwarning("Continue?", f"{name} has sent you ${amount}", icon="question")
messagebox.showwarning("Info", f"${amount} has just been transferred to your account!", icon="info")
menu(usrn)
except:
print("Error!")
else:
print("Nothing Today!")

How to deal with NAT python socket

I am trying to make an application which is accessible for a wide range of users.
Its some basic socket + python networking stuff.
I researched a bit recently and I tried a few things.
I implemented some UPNP stuff via miniupnpc but the thing is that you need a permission to use UPNP on most routers which is not ideal for my needs. I am trying to completely bypass things like port forwarding.
I also tried to completely switch from Python socket to pyp2p but I could't get it working because of the lack of documentation and maintenance on the project.
Is there an easy way to bypass NAT and if yes how ?
Client:
import socket
import struct
import os
import pickle
from pygame import mixer
def connect(host, port):
ourmusic = []
fileBRAIN = []
musicPath = './music'
s = socket.socket()
print('created socket')
s.connect((host,port))
print('conected to ',host)
#identify self
hostname = socket.gethostname()
IPAddr = socket.gethostbyname(hostname)
IPAddrBYTE = str(IPAddr).encode('utf-8')
send_msg(s, IPAddrBYTE)
if os.path.exists(str(host)) == True :
print('server seen previously')
#load host's song list
fileBRAIN = pickle.load(open( str(host), 'rb'))
#recieve new files from host
receiveFiles(s, fileBRAIN)
#compare files
saveMusicList(ourmusic, musicPath)
filesToTransmit = diff(ourmusic, fileBRAIN)
#transmit music which host dont have
transmitFiles(s , filesToTransmit, fileBRAIN)
#save host's song list
pickle.dump(fileBRAIN, open(str(host), 'wb'))
#start playing music
clientMainLoop(s)
else:
print('server not seen previously')
#recieve music files from host
receiveFiles(s, fileBRAIN)
#compare files
saveMusicList(ourmusic, musicPath)
filesToTransmit = diff(ourmusic, fileBRAIN)
#transmit music which host dont have
transmitFiles(s , filesToTransmit, fileBRAIN)
#save host's song list
pickle.dump(fileBRAIN, open(str(host), 'wb'))
#start playing music
clientMainLoop(s)
def clientMainLoop(socket):
mixer.init()
while True:
randomsongBYTE = recv_msg(socket)
randomsong = randomsongBYTE.decode('utf-8')
mixer.music.load('./music/' + randomsong)
mixer.music.play()
print('now playing: ' + randomsong)
while mixer.music.get_busy() == True:
temp = 0
else:
print('music ended receiving next...')
def transmitFiles(socket, files, fileBRAIN):
Transmissions = struct.pack('i',len(files))
send_msg(socket, Transmissions)
for x in files:
filename = str(x).encode('utf-8')
send_msg(socket, filename)
file = open('./music/' + x , 'rb')
file_data = file.read()
send_msg(socket, file_data)
fileBRAIN.append(str(x))
print(x + '\n' + 'has been send transmitted successfully')
print('')
def receiveFiles(s, fileBRAIN):
i = 1
transmissionsDATA = recv_msg(s)
transmissionsTUP = struct.unpack('i',transmissionsDATA)
transmissions = transmissionsTUP[0]
print('there are ' + str(transmissions) + ' awaiting receive
transmissions')
while i <= transmissions:
BYTEfilename = recv_msg(s)
filename = BYTEfilename.decode('utf-8')
file = open('./music/' + filename, 'wb')
file_data = recv_msg(s)
file.write(file_data)
file.close()
fileBRAIN.append(str(filename))
print('transmission ' + str(i) + ' recieived')
i = i + 1
def saveMusicList(musiclist, musicPath):
for entry in os.listdir(musicPath):
if os.path.isfile(os.path.join(musicPath, entry)):
musiclist.append(entry)
#find elements which are not in the other list
def diff(li1, li2):
return (list(set(li1) - set(li2)))
#TCP msg protocoll
def send_msg(sock, msg):
# Prefix each message with a 4-byte length (network byte order)
msg = struct.pack('>I', len(msg)) + msg
sock.sendall(msg)
def recv_msg(sock):
# Read message length and unpack it into an integer
raw_msglen = recvall(sock, 4)
if not raw_msglen:
return None
msglen = struct.unpack('>I', raw_msglen)[0]
# Read the message data
return recvall(sock, msglen)
def recvall(sock, n):
# Helper function to recv n bytes or return None if EOF is hit
data = bytearray()
while len(data) < n:
packet = sock.recv(n - len(data))
if not packet:
return None
data.extend(packet)
return data
Server :
import socket
import os
import struct
import pickle
import miniupnpc
from random import randint
from pygame import mixer
def init(port):
fileBRAIN = []
ourmusic = []
files = []
musicPath = './music'
try:
#Network Gateway (port forwarding)
upnp = miniupnpc.UPnP()
upnp.discoverdelay = 10
upnp.discover()
upnp.selectigd()
upnp.addportmapping(port, 'TCP', upnp.lanaddr, port,
'OpenMCS', '')
except:
print('INFO:Port is already forwarded or you dont have the
premission to forward it')
s = socket.socket()
host = ('') #socket.gethostname()
s.bind((host,port))
s.listen(5)
print(host)
print('waiting for any incoming conections ... ')
conn,addr = s.accept()
#get client identity
ClientIPAddrBYTE = recv_msg(conn)
ClientIPAddr = ClientIPAddrBYTE.decode('utf-8')
if os.path.exists(ClientIPAddr) == True :
print('client seen previously')
#load client's song list
fileBRAIN = pickle.load(open( ClientIPAddr, 'rb'))
#compare files
saveMusicList(ourmusic, musicPath)
filesToTransmit = diff(ourmusic, fileBRAIN)
#transmit new files client doesn't have
transmitFiles(conn, filesToTransmit, fileBRAIN)
#recieve music files we dont have
receiveFiles(conn, fileBRAIN)
#save client's song list
pickle.dump(fileBRAIN, open(ClientIPAddr, 'wb'))
#start playing music
serverMainLoop(conn, ourmusic, musicPath)
else:
print('client not seen previously')
#transmit own music files to client
transmitFiles(conn, files, fileBRAIN)
#recieve music files we dont have
receiveFiles(conn, fileBRAIN)
#save client's song list
pickle.dump(fileBRAIN, open(ClientIPAddr, 'wb'))
#start playing music
serverMainLoop(conn, ourmusic, musicPath)
def serverMainLoop(socket, ourmusic, musicPath):
saveMusicList(ourmusic, musicPath)
mixer.init()
while True:
randomsong = ourmusic[randint(0, (len(ourmusic) - 1 ))]
randomsongBYTE = randomsong.encode('utf-8')
send_msg(socket, randomsongBYTE)
mixer.music.load('./music/' + randomsong)
mixer.music.play()
print('now playing: ' + randomsong)
while mixer.music.get_busy() == True:
temp = 0
else:
print('music ended picking next...')
def transmitFiles(socket, files, fileBRAIN):
Transmissions = struct.pack('i',len(files))
send_msg(socket, Transmissions)
for x in files:
filename = str(x).encode('utf-8')
send_msg(socket, filename)
file = open('./music/' + x , 'rb')
file_data = file.read()
send_msg(socket, file_data)
fileBRAIN.append(str(x))
print(x + '\n' + 'has been send transmitted successfully')
print('')
def receiveFiles(s, fileBRAIN):
i = 1
transmissionsDATA = recv_msg(s)
transmissionsTUP = struct.unpack('i',transmissionsDATA)
transmissions = transmissionsTUP[0]
print('there are ' + str(transmissions) + ' awaiting receive
transmissions')
while i <= transmissions:
BYTEfilename = recv_msg(s)
filename = BYTEfilename.decode('utf-8')
file = open('./music/' + filename, 'wb')
file_data = recv_msg(s)
file.write(file_data)
file.close()
fileBRAIN.append(str(filename))
print('transmission ' + str(i) + ' recieved')
i = i + 1
def saveMusicList(musiclist, musicPath):
for entry in os.listdir(musicPath):
if os.path.isfile(os.path.join(musicPath, entry)):
musiclist.append(entry)
#find elements which are not in the other list
def diff(li1, li2):
return (list(set(li1) - set(li2)))
#TCP msg proctocoll
def send_msg(sock, msg):
# Prefix each message with a 4-byte length (network byte order)
msg = struct.pack('>I', len(msg)) + msg
sock.sendall(msg)
def recv_msg(sock):
# Read message length and unpack it into an integer
raw_msglen = recvall(sock, 4)
if not raw_msglen:
return None
msglen = struct.unpack('>I', raw_msglen)[0]
# Read the message data
return recvall(sock, msglen)
def recvall(sock, n):
# Helper function to recv n bytes or return None if EOF is hit
data = bytearray()
while len(data) < n:
packet = sock.recv(n - len(data))
if not packet:
return None
data.extend(packet)
return data
You can find the full code here if you need it : https://github.com/Finn1510/OpenMCS

EOFError in converting string to list

I have a code which is running on 2 hosts. They are processing some photos. When host1 receives a message, it will send some of its photos to host2 for processing. It will also send a list to host2 (it will convert it to string and then it will send it).
import pickle
import time, threading
host = commands.getoutput("hostname -I")
port = 5005
i = 0
backlog = 5
BUFSIZE = 4096
queueList = []
start = []
end = []
l = threading.Lock()
def read_udp(s):
data,addr = s.recvfrom(1024)
global start
if data.startswith('10.0.0'):
print("received message:", data)
data_split = data.split(" ")
address = data_split[0]
num = int(data_split[1])
ipToTransfer = address
l.acquire()
transferList = queueList[-num:]
del queueList[-num:]
transferStart = start[-num:]
del start[-num:]
l.release()
msg = pickle.dumps(transferStart)
#udp_send('New Transfer', ipToTransfer)
udp_send(msg, ipToTransfer)
send_file(ipToTransfer, transferList)
else:
recvStart = pickle.loads(data)
print("start before add::: ", start)
print("received::: ", recvStart)
l.acquire()
start = start + recvStart
l.release()
print("start after add::: ", start)
def udp_send(s, ip):
UDP_IP = ip
if(type(s) == str):
MESSAGE = s
else:
MESSAGE = pickle.dumps(s)
#print(MESSAGE)
print ("UDP target IP & port:", UDP_IP, port)
print ("message:", MESSAGE)
sock3 = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) # UDP
sock3.sendto(MESSAGE, (UDP_IP, port))
class Receiver:
''' Buffer binary data from socket conn '''
def __init__(self, conn):
self.conn = conn
self.buff = bytearray()
def get(self, size):
''' Get size bytes from the buffer, reading
from conn when necessary
'''
while len(self.buff) < size:
data = self.conn.recv(BUFSIZE)
if not data:
break
self.buff.extend(data)
# Extract the desired bytes
result = self.buff[:size]
# and remove them from the buffer
del self.buff[:size]
return bytes(result)
def save(self, fname):
''' Save the remaining bytes to file fname '''
with open(fname, 'wb') as f:
if self.buff:
f.write(bytes(self.buff))
while True:
data = self.conn.recv(BUFSIZE)
if not data:
break
f.write(data)
def send(sock2, data2):
while data2:
sent = sock2.send(data2)
data2 = data2[sent:]
def send_file(ipToTransfer, transferList):
while transferList:
fname = transferList.pop(0)
print("transferring:", fname)
with open(fname, 'rb') as f:
sock2 = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
try:
sock2.connect((ipToTransfer, 5005))
except socket.error as err:
print(err, ipToTransfer, 5005)
sock2.close()
return
# Send the file name length & the filename itself in one packet
send(sock2, pack('B', len(fname)) + fname.encode())
while True:
data2 = f.read(BUFSIZE)
if not data2:
break
send(sock2, data2)
sock2.close()
When host2 receives this string, it will convert it to list again, but I receive an EOFError in this part. My cmd doesn't have the copy capability, so I upload the photo from this error:
What's wrong?

you delete the pointer to what is being pickled
transferStart = start[-num:]
del start[-num:]
l.release()
msg = pickle.dumps(transferStart)
If you are trying to remove elements from a list that is not the way to do it. Consider popping or reassigning into another list that does not have that element, etc.

socket programming client freezing python

Basically, I have a python client to send command to ask server do somethings, I have implemented threading, but it seems not working. For example, when I send "start" command to the server, it will execute job_function, but during this time, the client is freezing. So basically, I want my server still able to respond to client's request, while executing tasks, and that's the reason I use thread.
Server.py:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind(('127.0.0.1', 5005)) # Bind to the port
s.listen(1) # Now wait for client connection.
c, addr = s.accept() # Establish connection with client.
while True:
print('Got connection from', addr)
data = c.recv(1024).decode()
print(data)
if data == "start":
print("start the service")
c.sendall('started service'.encode())
threading.Thread(target=job_function).start()
elif data == "suspend":
print("suspend service")
c.sendall('suspended service'.encode())
else:
c.sendall('wrong command'.encode())
c.close() # Close the connection
Client.py:
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(('127.0.0.1',5005))
while True:
x = input("Enter command: ")
s.sendall(x.encode())
print(x)
data = s.recv(1024).decode()
print(data)
s.close()

It can also be done only using recv() function.
client side:
sssize = os.stat('fileName').st_size
file = open('fileName', 'rb')
amm = file.read(sssize)
dfd = amm
#########
c.send(bytes(str(sssize), 'utf-8'))
rrespo = c.recv(1024).decode()
######
if rrespo == 'yess':
m = 0
lenmsg = 1024
loop = (int((sssize) / lenmsg))
if (sssize)<lenmsg:
c.send(dfd[0:sssize])
else:
dddf='oksend'
for ioo in range(0, loop):
if dddf=='oksend':
c.send(dfd[ioo * lenmsg:ioo * lenmsg + lenmsg])
stloop = ioo * lenmsg + lenmsg
print(int(m / (loop - 1) * 100))
m = m + 1
dddf = c.recv(6).decode()
print(dddf, ioo)
nextloop = sssize - loop * lenmsg
if nextloop > 0:
c.send(dfd[stloop:stloop + nextloop])
file.close()
print('file transffered successfully')
Server Side:
filename = input(str("Enter file name :")
fill = open(filename, 'wb')
c.send(bytes(commm, 'utf-8'))
# sizze=c.recv(1024).decode()
# print('size')
# print(sizze)
# c.send(bytes('done', 'utf-8'))
fileSize = c.recv(1024).decode()
c.send(bytes('yess', 'utf-8'))
lenmsg=1024
loop = int(int(fileSize) / lenmsg)
if (int(fileSize))<lenmsg:
image = c.recv(int(fileSize))
fill.write(image)
else:
for i in range(0, loop):
image = c.recv(lenmsg)
fill.write(image)
print('completed downloading:', int((i / (loop - 1) * 100)), '%')
c.send(bytes('oksend', 'utf-8'))
nextloop = int(fileSize) - loop * lenmsg
if nextloop > 0:
image = c.recv(nextloop)
fill.write(image)
fill.close()
print('file downloaded successfully')

print contents of file - python socket

I'm trying to print the contents of a file to the client using the defined command 'get'. I am not getting the contents of the file instead the contents are getting over written with Server Says... get test.txt.
Here is my client code:
import socket
import sys
import os
HOST = 'localhost'
PORT = 8082
size = 1024
def ls():
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST,PORT))
s.send(userInput)
result = s.recv(size)
print result
s.close()
return
def put(commandName):
socket1 = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
socket1.connect((HOST, PORT))
socket1.send(commandName)
string = commandName.split(' ', 1)
inputFile = string[1]
with open(inputFile, 'rb') as file_to_send:
for data in file_to_send:
socket1.sendall(data)
print 'PUT Successful'
socket1.close()
return
def get(commandName):
socket1 = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
socket1.connect((HOST, PORT))
socket1.send(commandName)
string = commandName.split(' ', 1)
inputFile = string[1]
with open(inputFile, 'wb') as file_to_write:
while True:
data = socket1.recv(1024)
print data
if not data:
break
print data
file_to_write.write(data)
file_to_write.close()
print 'GET Successful'
#socket1.close()
return
done = False
while not done:
userInput = raw_input()
if "quit" == userInput:
done = True
elif "ls" == userInput:
ls()
else:
string = userInput.split(' ', 1)
if (string[0] == 'put'):
put(userInput)
elif (string[0] == 'get'):
get(userInput)
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST,PORT))
s.send(userInput)
data = s.recv(size)
s.close()
print 'Received:', data
And server code:
import socket
import os
import sys
host = ''
port = 8082
backlog = 5
size = 1024
serverID = socket.gethostbyname(socket.gethostname())
info = 'SERVER ID: {} port: {}'.format(serverID, port)
print info
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((host,port))
s.listen(backlog)
done = False
# Loop until client sends 'quit' to server
while not done:
client, address = s.accept()
data = client.recv(size)
print "Server received: ", data
if data:
client.send("Server Says... " + data)
if data == "quit":
done = True
elif data == "ls":
data = os.listdir("C://")
client.send(data[0])
else:
string = data.split(' ', 1)
dataFile = string[1]
if (string[0] == 'put'):
with open(dataFile, 'wb') as file_to_write:
while True:
data = client.recv(1024)
if not data:
break
file_to_write.write(data)
file_to_write.close()
break
print 'Receive Successful'
elif (string[0] == 'get'):
with open(dataFile, 'rb') as file_to_send:
for data in file_to_send:
client.send(data)
print 'Send Successful'
client.close()
s.close()
print "Server exiting."

You are getting the content of the file but it is empty... and your code works just because you probably run it in the same directory.
Your client open file to write (and then it is empty) and the server reads it (both code use the same file name). You probably wanted to read file from C:\ so you should change server code and replace line:
with open(dataFile, 'rb') as file_to_send:
with:
with open('C:\\' + dataFile, 'rb') as file_to_send:

No matter what you send to the server this condition is true so you get "server says..."
if data:
client.send("Server Says... " + data)
You have also several flaws in you client I think. Like your commands are sent 2 times: once in the client 'main' when you do:
s.send(userInput)
And once in the functions like get and ls :
socket1.send(commandName)