Develop Reference

How to receive input from python socket server in android studio?

I have a python socket server that receives a string from an Android app and should return the same string in uppercase. The app can send the string and I receive it in the server but how could I receive the returned string in the Android studio?
Here is my python code:
import socket
HOST = "127.0.0.1" # Standard loopback interface address (localhost)
PORT = 65432 # Port to listen on (non-privileged ports are > 1023)
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
s.bind((HOST, PORT))
s.listen()
conn, addr = s.accept()
with conn:
print(f"Connected by {addr}")
while True:
data = conn.recv(1024)
print(data)
if not data:
break
conn.sendall(data.upper())
Here is my sending message function
Socket s;
PrintWriter pw;
#Override
protected Void doInBackground(String... voids) {
String message = voids[0];
byte[] messageByte = new byte[1000];
boolean end = false;
String dataString = "";
try {
s = new Socket("10.0.2.2", Integer.parseInt("65432"));
//sending data
pw = new PrintWriter(s.getOutputStream());
pw.write(message);
pw.flush();
pw.close();
//////////
//receiving data
s.close();
} catch (IOException e) {
e.printStackTrace();
}

Socket server between Unity and Raspberry doesn't connect

So I am trying to send data from the raspberry pi to unity.
I trying to create socket server to do so.
I can get the socket server running on the raspberry pi and can also look at the port with netstat -tulpn | grep :5005 in the terminal on the machine where the python script is running.
I also tried it on my mac and it also showed up as a TCP-server.
However when I try to connect to the same port and ip via Unity or on another machine it doesn't work. I also can't seem to find the port when listing all of the ports with netstat.
Unity spits out a "Connection refused" error.
Here is the code in Unity in C#
using UnityEngine;
using System.Collections;
using System;
using System.IO;
using System.Net.Sockets;
public class ClientSocket : MonoBehaviour
{
bool socketReady = false;
TcpClient mySocket;
public NetworkStream theStream;
StreamWriter theWriter;
StreamReader theReader;
public String Host = "192.168.8.137";
public Int32 Port = 5005;
void Start()
{
setupSocket();
TextMessage("SocketTest");
}
public void setupSocket()
{ // Socket setup here
try
{
mySocket = new TcpClient(Host, Port);
theStream = mySocket.GetStream();
theWriter = new StreamWriter(theStream);
theReader = new StreamReader(theStream);
socketReady = true;
}
catch (Exception e)
{
Debug.Log("Socket error:" + e); // catch any exceptions
}
}
public void TextMessage(string message)
{
if (socketReady == true)
{
theWriter.Write(message);
theWriter.Flush();
}
}
}
here is the code in python, which should be running on the raspberry pi.
import socket
import sys
backlog = 1
size = 1024
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind(('192.168.8.137', 5005))
s.listen(1)
try:
print ("is waiting")
client, address = s.accept()
while 1:
data = client.recv(size)
if data:
print (data)
finally:
print("closing socket")
cient.close()
s.close()
I'm new to socket servers, but I really trying to accomplish a connection here.
Thanks for reading!

am pretty sure you need to encode the data that you about to send in c# TcpClient
adding an example from my final project:
string data = "Hello Server!"; //the message in string (important it will be string)
byte[] msg = Encoding.Unicode.GetBytes(data); //encoded the message using unicode (utf-16)
NetworkStream stream = client.GetStream(); //get the tcp client stream
stream.Write(msg, 0, msg.Length); //write the message to the stream
and in the server you suppose to have something like that:
msg = clnt.recv(1024) #reciving the data
msg = msg.decode("utf-16") #decoding the data
print(msg) #printing the data
and i think thats it
and i would recommend using port above 10000 because most of the ports can be used

How to connect android phone client to python server on same network using socket programming?

I am trying to connect my android app (client) to my PC (python server). They are both on the same network. I can ping my android phone from my PC and PC from phone. But when I try to connect them using sockets android app gets stuck at connecting and after a while throws a timeout exception.
Here is the code of Android Client class:
public class Client extends AsyncTask<Void, Void, Void> {
private String mCommand;
private String mHostIP;
public Client(String mCommand, String mHostIP) {
this.mCommand = mCommand;
this.mHostIP = mHostIP;
}
#Override
protected Void doInBackground(Void... voids) {
try {
InetAddress serverAddr = InetAddress.getByName(mHostIP);
Socket soc = new Socket(serverAddr,9999);
OutputStream toServer = soc.getOutputStream();
PrintWriter output = new PrintWriter(toServer);
output.println(mCommand);
DataOutputStream out = new DataOutputStream(toServer);
out.writeBytes(mCommand);
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
}
It gets stuck at new Socket and throws exception after a while.
Here is the code for Python server:
import socket
import os
hostname = socket.gethostname()
IPAddr = socket.gethostbyname(hostname)
print('My IP: '+IPAddr)
port = 9999
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print ("socket successfully created")
server_address = ('192.168.10.4', 9999)
s.bind(server_address)
s.listen(1)
print ("socket is listening")
while True:
try:
c, addr = s.accept()
print ('Got connection from', addr)
type = c.recv(1024).decode('utf-8')
print(type)
finally:
print('Could not connect')
c.close()
break

Have a close look at your firewall.

Simple python TCP server with sending command to communicate with esp32

I'm new to python programming. I want to create a simple TCP server working with an esp32. The idea of this is to send command data = '{\"accel\",\"gyro\",\"time\":1}' to esp32 via socket and then wait around 10ms for reply from esp32. I tried many examples but nothing works. ESP32 gets my message from this program but I can't receive message from esp32.
import socket
# bind all IP address
HOST = '192.168.137.93'
# Listen on Port
PORT = 56606
#Size of receive buffer
localhost=('0.0.0.0', 56606)
BUFFER_SIZE = 1024
# Create a TCP/IP socket
data = '{\"accel\",\"gyro\",\"time\":1}'
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
# Bind the socket to the host and port
s.connect((HOST, PORT))
# send data to server
s.send(bytearray(data, 'utf-8'))
s.serve_forever()
print('Listen for incoming connections')
sock.listen(1)
while True:
client, addr = s.accept()
while True:
content = client.recv(1024)
if len(content) ==0:
break
else:
print(content)
print("Closing connection")
client.close()
I tried more and tried to use other code(see below). Now I get message back but on other port(I can track it by wireshark)
import socket
# Ip of local host
HOST = '192.168.137.93'
# Connect to Port
PORT = 56606
#Size of send buffer
BUFFER_SIZE = 4096
# data to sent to server
message = '{\"accel\",\"gyro\",\"time\":1}'
# Create a TCP/IP socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
# Connect to server
s.connect((HOST, PORT))
# send data to server
s.send(bytearray(message, 'utf-8'))
# Receive response from server
data = ""
while len(data) < len(message):
data = s.recv(BUFFER_SIZE)
# Close connection
print ('Server to Client: ' , data)
s.close()
I don't use both of these codes together.
Any hints?

Reuse the same socket to send and receive (Python)

I have written a simple script to send and receive messages using the Python socket module. I want to first send a message using sendMsg and then receive a response using listen. sendMsg works fine but when my server sends a response I receive the error:
"[WinError 10038] An operation was attempted on something that is not a socket"
I close the socket connection in sendMsg and then try to bind it in listen, but it's at this line that the error is produced. Please could someone show me what I am doing wrong!
import socket
port = 3400
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((socket.gethostname(), port))
def sendMsg():
print("\nSending message:\n\n")
msg = ("Sample text").encode("utf-8")
s.send(msg)
s.close()
def listen():
s.bind(("", port))
s.listen(1)
serverSocket, info = s.accept()
print("Connection from", info, "\n")
while 1:
try:
buf = bytearray(4000)
view = memoryview(buf)
bytes = serverSocket.recv_into(view, 4000)
if bytes:
stx = view[0]
Size = view[1:3]
bSize = Size.tobytes()
nTuple = struct.unpack(">H", bSize)
nSize = nTuple[0]
message = view[0:3+nSize]
messageString = message.tobytes().decode("utf-8").strip()
messageString = messageString.replace("\x00", "")
else:
break
except socket.timeout:
print("Socket timeout.")
break
sendMsg()
listen()
Note: I have implemented listen in a separate client and used the line
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 3)
before s.bind() and s.connect(). This works OK. It would be nice to have it all in one client though.

As per the docs the socket.close() will close the socket and no further operations are allowed on it.
So in your code this line s.close() is closing the socket.
Because of that the s.bind(("", port)) will not work as the socket s is already closed!