secure-chat/server/main.py

#!/usr/bin/env python3
# coding: utf8

import json
import logging
import logging.config
import os
import socket
import threading


#### logging ####
# json decoder for int keys
from Crypto.Cipher import PKCS1_OAEP
from Crypto.PublicKey import RSA
from Crypto.Random import get_random_bytes


def make_hashable(o):
    if isinstance(o, (tuple, list)):
        return tuple((make_hashable(e) for e in o))
    elif isinstance(o, dict):
        return tuple(sorted((k, make_hashable(v)) for k, v in o.items()))
    elif isinstance(o, (set, frozenset)):
        return tuple(sorted(make_hashable(e) for e in o))
    return o


class Decoder(json.JSONDecoder):
    def decode(self, s, **kwargs):
        result = super().decode(s)  # result = super(Decoder, self).decode(s) for Python 2.x
        return self._decode(result)

    def _decode(self, o):
        if isinstance(o, str):
            try:
                return int(o)
            except ValueError:
                return o
        elif isinstance(o, dict):
            return {k: self._decode(v) for k, v in o.items()}
        elif isinstance(o, list):
            return [self._decode(v) for v in o]
        else:
            return o


def setup_logging(default_path='log_config.json', default_level=logging.INFO, env_key='LOG_CFG'):
    """Setup logging configuration
    """
    path = default_path
    value = os.getenv(env_key, None)
    if value:
        path = value
    if os.path.exists(path):
        with open(path, 'rt') as f:
            config = json.load(f)
        logging.config.dictConfig(config)
    else:
        logging.basicConfig(level=default_level)


setup_logging()

log_server = logging.getLogger('server')

debug = log_server.debug
info = log_server.info
warning = log_server.warning
error = log_server.error
critical = log_server.critical

#### Variables ####
HOST = ''
PORT = 8888
BUFFER_SIZE = 4096
BEGIN_MESSAGE = bytes("debut".ljust(BUFFER_SIZE, ";"), "ascii")
END_MESSAGE = bytes("fin".ljust(BUFFER_SIZE, ";"), "ascii")

VERSION = "EICP2P2 V1"

DONE = 0
ERROR = 1


#### Socket ####
main_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
main_socket.bind((HOST, PORT))


#### Threads ####
class clientThread(threading.Thread):
    """Main thread, for each client"""

    def __init__(self, clientsocket, ip, port):
        """Create clientThread object

        :param clentsocket: Client's socket
        :param ip: Client's ip address
        :param port: Client's connection PORT
        :type clientsocket: socket.socket
        :type ip: str
        :type port: int

        :return: Nothing
        :rtype: NoneType"""
        debug("Creation du thread pour %s" % ip)
        threading.Thread.__init__(self)  # initialisation du thread
        self.client = clientsocket
        self.ip = ip
        self.port = port
        self.running = True
        self.status = None
        debug("Creation du thread pour %s reussie" % ip)

    def initialize(self):
        """Interpret request header"""
        # Receive message
        chunk = bytes("", "ascii")
        while chunk != BEGIN_MESSAGE:
            chunk = self.client.recv(BUFFER_SIZE)
        last_chunk = chunk
        while last_chunk != END_MESSAGE:
            last_chunk = self.client.recv(BUFFER_SIZE)
            chunk += last_chunk
        # Remove the begening and the end of chunk
        util_part = chunk[BUFFER_SIZE:-BUFFER_SIZE]
        print(util_part)
        header = util_part[:BUFFER_SIZE]
        print(header)
        content = util_part[BUFFER_SIZE:]
        header_txt = header.decode("ascii").rstrip(";")
        version = header_txt.split("\n")[0]
        # Extraction des champs du header
        if version != VERSION:
            debug("Pas la bonne version")
            self.send(b"Error".ljust(BUFFER_SIZE, b";"))
        champs = {l.split(": ")[0]: l.split(": ")[1] for l in header_txt.split('\n')[1:]}

        if champs.get("type", None) is None:
            debug("Le champ type n'est pas dans le header")
            self.send(b"Error".ljust(BUFFER_SIZE, b";"))
            return

        if self.status is None and champs["type"] != "RSASend":
            debug("Requête différente de RASSend avec une connection non initialisée")
            self.send(b"Error".ljust(BUFFER_SIZE, b";"))
            return

        if champs["type"] == "RSASend":
            debug("Réception de la clef RSA de %s", self.ip)
            self.rsa_client = content.rstrip(b";").rstrip(b' ')
            self.aes_key = get_random_bytes(64)
            header = bytes((VERSION+"\ntype: init").ljust(BUFFER_SIZE, ";"), 'ascii')
            content = self.aes_key.ljust(BUFFER_SIZE, b";")
            self.send_rsa(header+content)
            return

    def send_rsa(self, to_send):
        if self.rsa_client is None:
            debug("Clef RSA non recue")
            self.client.send(b"Error".ljust(BUFFER_SIZE))
            return
        # Transform rsakey and generate sessionkey
        recipient_key = RSA.import_key(self.rsa_client)
        # RSA crypter object
        cipher_rsa = PKCS1_OAEP.new(recipient_key)
        # Encrypt session_key
        crypted = b""
        for to_send_text in [to_send[i:i + 16] for i in range(0, len(to_send), 16)]:
            crypted += cipher_rsa.encrypt(to_send_text)
        self.send(crypted)

    def send(self, to_send):
        self.client.send(BEGIN_MESSAGE)
        i=0
        for to_send_text in [to_send[i:i + BUFFER_SIZE] for i in range(0, len(to_send), BUFFER_SIZE)]:
            self.client.send(to_send_text.ljust(BUFFER_SIZE, b";"))
            i+=1
        print(i)
        self.client.send(END_MESSAGE)


    def run(self):  # main de la connection du client
        """Run thread mainloop

        :return: Nothing
        :rtype: NoneType"""
        self.initialize()
        print("done")
        self.client.close()


if __name__ == "__main__":
    clients = []
    while True:
        main_socket.listen(1)  # ecoutes des connections entrantes
        clientsocket, (ip, PORT) = main_socket.accept()
        newClient = clientThread(clientsocket, ip, PORT)
        newClient.start()
        clients.append(newClient)