How to fix windows decline error for lan file transfer - python-3.x

Question

I'm a 14 year old beginner in software design but have good knowledge in python basic and acute amounts in networking. i recently got a raspberry pi 3 b+ brand new and am trying to make a python program that will allow me to transmit information input from my hp PC to my pi so it can display the info, this project is to help me with school, i have code typed and it runs but when i try to run the "client code", this is so my pi can receive the input data, i get an error saying that the device has declined my connection request, what should i do to fix the issue? if you want to see the code i can post it, but i'm not sure if that is necessary.
i only tried changing the port number in both programs, since that is not the issue and i' new to LAN and networking, i haven't tried anything else.
as requested my code is:(not HTML, CSS, or HTML. it's just easier to use that interface.
# send.py
import socket # Import socket module
port = 60000 # Reserve a port for your service.
s = socket.socket() # Create a socket object
host = socket.gethostname() # Get local machine name
s.bind((host, port)) # Bind to the port
s.listen(5) # Now wait for client connection.
print 'Server listening....'
while True:
conn, addr = s.accept() # Establish connection with client.
print 'Got connection from', addr
data = conn.recv(1024)
print('Server received', repr(data))
filename='mytext.txt'
f = open(filename,'rb')
l = f.read(1024)
while (l):
conn.send(l)
print('Sent ',repr(l))
l = f.read(1024)
f.close()
print('Done sending')
conn.send('Thank you for connecting')
conn.close()
# recieve.py
import socket # Import socket module
s = socket.socket() # Create a socket object
host = socket.gethostname() # Get local machine name
port = 60000 # Reserve a port for your service.
s.connect((host, port))
s.send("Hello server!")
with open('received_file', 'wb') as f:
print 'file opened'
while True:
print('receiving data...')
data = s.recv(1024)
print('data=%s', (data))
if not data:
break
# write data to a file
f.write(data)
f.close()
print('Successfully get the file')
s.close()
print('connection closed')

Answer 1

Unfortunately, this answer requires Python 3.5+.
Before running this code please make sure you've worked out which IP you will be using for your server and client (help at the bottom).
Step 1 - Ensure a simple ping works
Server code:
import socket
# FIND IP
# The IP to use will be different depending
# on whether you have WiFi or Ethernet, so
# you need to choose whichever one that is
ips = socket.gethostbyname_ex(socket.gethostname())[-1]
print(*[f"{i}: {j}" for i, j in enumerate(ips)], sep="\n")
ip = ips[int(input(" > "))]
# SELECT PORT
port = 10000
#SETUP SERVER
# Create server socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.bind((ip, port))
# A queue of 1 clients is more than enough for our application
sock.listen(1)
print(f"Listening on {ip}:{port}")
while True:
try:
(clientsock, address) = sock.accept()
# so if there's nothing to read we don't wait too long
clientsock.settimeout(0.01)
ping_string = clientsock.recv(5).decode()
if ping_string == "ping!":
print("ping!")
clientsock.sendall(b"ping!")
else:
print("no ping!")
print(ping_string)
clientsock.sendall(b"nopng")
clientsock.shutdown(1)
clientsock.close()
except KeyboardInterrupt:
# Add a way to safely exit the infinite loop
break
sock.close()
Client code:
import socket
# GET IP
print("IP of server")
ip = input(" > ")
# SELECT PORT
port = 10000
# SETUP SOCKET
# Create server socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((ip, port))
print(f"Conencted to {ip}:{port}")
# so if there's nothing to read we don't wait too long
sock.settimeout(0.01)
sock.sendall(b"ping!")
ping_string = sock.recv(5).decode()
if ping_string == "ping!":
print("ping!")
else:
print("no ping!")
sock.close()
OUTPUT:
Server:
0: 192.168.56.1
1: 192.168.1.151
> 1
Listening on 192.168.1.151:10000
Client:
Type ip of server
> 192.168.1.151
Conencted to 192.168.1.151:10000
ping!
If this doesn't work, make sure your computer can ping your raspberry pi, and vice versa. Go into CMD (I presume your HP PC is Windows) and type ping ____ (replacing ____ with the internal ip address of your raspberry pi.
If the terminal doesn't appear to be pinging something, you need to go onto your computer and raspberry pi to find they're internal ips, which you can find out how to do online.
Step 2 - The fun part
We're now going to setup your file server.
Server code:
import socket
# OPEN FILE TO SEND ACROSS
with open("filesend.txt", mode="rb") as file:
file_string = file.read()
# FIND IP
# The IP to use will be different depending
# on whether you have WiFi or Ethernet, so
# you need to choose whichever one that is
ips = socket.gethostbyname_ex(socket.gethostname())[-1]
print(*[f"{i}: {j}" for i, j in enumerate(ips)], sep="\n")
ip = ips[int(input(" > "))]
# SELECT PORT
port = 10000
#SETUP SERVER
# Create server socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.bind((ip, port))
# A queue of 1 clients is more than enough for our application
sock.listen(1)
print(f"Listening on {ip}:{port}")
while True:
try:
(clientsock, address) = sock.accept()
# so if there's nothing to read we don't wait too long
clientsock.settimeout(0.01)
# send length
clientsock.sendall((str(len(file_string)) + ".").encode())
clientsock.sendall(file_string)
print("Sent file!")
response_code = clientsock.recv(1).decode()
if response_code != "0":
print("ERROR! response was not 0")
print(response_code)
clientsock.shutdown(1)
clientsock.close()
except KeyboardInterrupt:
# Add a way to safely exit the infinite loop
break
sock.close()
Client code:
import socket
# SELECT IP
print("IP of server")
ip = input(" > ")
# SELECT PORT
port = 10000
# SETUP SOCKET
# Create server socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((ip, port))
print(f"Conencted to {ip}:{port}")
# so if there's nothing to read we don't wait too long
sock.settimeout(0.01)
# Get length of file sent across
len_string = ""
c = ""
while c != ".":
c = sock.recv(1).decode()
len_string += c
length = int(len_string[:-1])
file_string = sock.recv(length)
# send a status code back to the server
sock.sendall(b"0")
with open("filerecv.txt", mode="wb") as file:
file.write(file_string)
print(file_string.decode())
sock.close()
OUTPUT:
Server:
0: 192.168.56.1
1: 192.168.1.151
> 1
Listening on 192.168.1.151:10000
Client:
IP of server
> 192.168.1.151
Conencted to 192.168.1.151:10000
THIS IS A TEST!
Once again, ensure the ip you tell the client to connect to is the same as the one you have selected from the list provided in the server script. Also ensure that the ip address can be connected to, ie don't use the one for when the pc's on WiFi if it's currently on Ethernet.
Hope this works for you. Any issues leave down in the comments :)
EDIT
WINDOWS
Sample output from ipconfig:
> ipconfig
Windows IP Configuration
Ethernet adapter Ethernet:
Connection-specific DNS Suffix . : home
IPv6 Address. . . . . . . . . . . : 2a00:23c6:6586:2400:e47a:c60e:812b:1123
IPv6 Address. . . . . . . . . . . : fdaa:bbcc:ddee:0:e47a:c60e:812b:1123
Temporary IPv6 Address. . . . . . : 2a00:23c6:6586:2400:d1fe:95f5:27c3:c4b8
Temporary IPv6 Address. . . . . . : fdaa:bbcc:ddee:0:d1fe:95f5:27c3:c4b8
Link-local IPv6 Address . . . . . : fe80::e47a:c60e:812b:1123%19
IPv4 Address. . . . . . . . . . . : 192.168.1.151
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : fe80::8aa6:c6ff:fe23:7a15%19
192.168.1.254
You're looking for this line:
IPv4 Address. . . . . . . . . . . : 192.168.1.151
And the IP is whatever value is at the end (eg 192.168.1.151)
FIND THE IP OF YOUR RASPBERRY PI
Unless you've changed some advanced settings your Raspberry Pi's hostname will be raspberrypi, or raspberrypi.local. I've seen both. If you want to know the IP address, use the Python script below, and try to ping all the IPs from the list it prints to find out which one IP is actually used by the Pi.
Run this on your PC:
import socket
host1 = "raspberrypi"
host2 = "raspberrypi.local"
try:
ip1 = socket.gethostbyname_ex(host1)[-1]
except:
ip1 = []
try:
ip2 = socket.gethostbyname_ex(host2)[-1]
except:
ip2 = []
print(list(set(ip1+ip2)))
Any more issues, please let me know :)