How to use socket with a Python client and a C++ server

I have a simple client/server program.

The client is written in python as this :

import socket
import sys

HOST, PORT = "localhost", 50007

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

s.connect((HOST, PORT))
for x in range(0, 10000):
    print("Step 1")
    s.send(b'Hello')
    print("Step 2")
    print(str(s.recv(1000)))
    print(x)

And I wrote a server in python like this :

import socket

HOST = ''
PORT = 50007
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((HOST, PORT))
s.listen(1)
conn, addr = s.accept()

while True:
    data = conn.recv(1024)
    conn.sendall(data)

I want to create a C++ version of the server. I did this :

#include <iostream>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <unistd.h>
#include <string>
#include <arpa/inet.h>
#include <string.h>
#include <stdio.h>

using namespace std;

#define SERVER_PORT htons(50007)

int main() {

        char buffer[1000];
        int n;

        int serverSock=socket(AF_INET, SOCK_STREAM, 0);

        sockaddr_in serverAddr;
        serverAddr.sin_family = AF_INET;
        serverAddr.sin_port = SERVER_PORT;
        serverAddr.sin_addr.s_addr = INADDR_ANY;

        /* bind (this socket, local address, address length)
           bind server socket (serverSock) to server address (serverAddr).  
           Necessary so that server can use a specific port */ 
        bind(serverSock, (struct sockaddr*)&serverAddr, sizeof(struct sockaddr));

        // wait for a client
        /* listen (this socket, request queue length) */
        listen(serverSock,1);

        while (1 == 1) {
                bzero(buffer, 1000);

                sockaddr_in clientAddr;
                socklen_t sin_size=sizeof(struct sockaddr_in);
                int clientSock=accept(serverSock,(struct sockaddr*)&clientAddr, &sin_size);

                //receive a message from a client
                n = read(clientSock, buffer, 500);
                cout << "Confirmation code  " << n << endl;
                cout << "Server received:  " << buffer << endl;

                strcpy(buffer, "test");
                n = write(clientSock, buffer, strlen(buffer));
                cout << "Confirmation code  " << n << endl;
        }
        return 0;
}

It works one time but it block at the line str(s.recv(1000)) of the client.

This is the output from the client :

Step 1
Step 2
b'test'
0
Step 1
Step 2

And this is the output from the server :

code  5
Server received:  Hello
code  4
code  5
Server received:  Hello
code  4

As you can see, the communication is like this :

1. The client send a message
2. The server receive the message
3. The server send a message
4. The client send another message
5. The server receive a message and seems to send another message but the client did not receive it.

What is my error?