megapy/mega/mega.py

import re
import json
from Crypto.Cipher import AES
from Crypto.PublicKey import RSA
from Crypto.Util import Counter
import os
import random
import binascii
import requests
import time
import shutil
from .errors import ValidationError, RequestError
from .crypto import *


class Mega(object):
    def __init__(self):
        self.schema = 'https'
        self.domain = 'mega.co.nz'
        self.timeout = 160  # max time (secs) to wait for resp from api requests
        self.sid = None
        self.sequence_num = random.randint(0, 0xFFFFFFFF)
        self.request_id = make_id(10)

    @classmethod
    def login(cls, email, password):
        instance = cls()
        instance.login_user(email, password)
        return instance

    def login_user(self, email, password):
        password_aes = prepare_key(str_to_a32(password))
        uh = stringhash(email, password_aes)
        resp = self.api_request({'a': 'us', 'user': email, 'uh': uh})
        #if numeric error code response
        if isinstance(resp, int):
            raise RequestError(resp)
        self._login_process(resp, password_aes)

    def _login_process(self, resp, password):
        encrypted_master_key = base64_to_a32(resp['k'])
        self.master_key = decrypt_key(encrypted_master_key, password)
        if 'tsid' in resp:
            tsid = base64_url_decode(resp['tsid'])
            key_encrypted = a32_to_str(
                encrypt_key(str_to_a32(tsid[:16]), self.master_key))
            if key_encrypted == tsid[-16:]:
                self.sid = resp['tsid']
        elif 'csid' in resp:
            encrypted_rsa_private_key = base64_to_a32(resp['privk'])
            rsa_private_key = decrypt_key(encrypted_rsa_private_key,
                                          self.master_key)

            private_key = a32_to_str(rsa_private_key)
            self.rsa_private_key = [0, 0, 0, 0]

            for i in range(4):
                l = ((ord(private_key[0]) * 256 + ord(private_key[1]) + 7) / 8) + 2
                self.rsa_private_key[i] = mpi_to_int(private_key[:l])
                private_key = private_key[l:]

            encrypted_sid = mpi_to_int(base64_url_decode(resp['csid']))
            rsa_decrypter = RSA.construct(
                (self.rsa_private_key[0] * self.rsa_private_key[1],
                 0L, self.rsa_private_key[2], self.rsa_private_key[0],
                 self.rsa_private_key[1]))

            sid = '%x' % rsa_decrypter.key._decrypt(encrypted_sid)
            sid = binascii.unhexlify('0' + sid if len(sid) % 2 else sid)
            self.sid = base64_url_encode(sid[:43])

    def api_request(self, data):
        params = {'id': self.sequence_num}
        self.sequence_num += 1

        if self.sid:
            params.update({'sid': self.sid})

        #ensure input data is a list
        if not isinstance(data, list):
            data = [data]

        req = requests.post(
            '{0}://g.api.{1}/cs'.format(self.schema, self.domain),
            params=params,
            data=json.dumps(data),
            timeout=self.timeout)
        json_resp = json.loads(req.text)

        #if numeric error code response
        if isinstance(json_resp, int):
            raise RequestError(json_resp)
        return json_resp[0]

    def parse_url(self, url):
        #parse file id and key from url
        if ('!' in url):
            match = re.findall(r'/#!(.*)', url)
            path = match[0]
            return path
        else:
            raise RequestError('Url key missing')

    def process_file(self, file, shared_keys):
        """
        Process a file
        """
        if file['t'] == 0 or file['t'] == 1:
            keys = dict(keypart.split(':', 1) for keypart in file['k'].split('/'))
            uid = file['u']
            key = None
            # my objects
            if uid in keys:
                key = decrypt_key(base64_to_a32(keys[uid]), self.master_key)
            # shared folders 
            elif 'su' in file and 'sk' in file and ':' in file['k']:
                shared_key = decrypt_key(base64_to_a32(file['sk']), self.master_key)
                key = decrypt_key(base64_to_a32(keys[file['h']]), shared_key)
                if file['su'] not in shared_keys:
                    shared_keys[file['su']] = {}
                shared_keys[file['su']][file['h']] = shared_key
            # shared files
            elif file['u'] and file['u'] in shared_keys:
                for hkey in shared_keys[file['u']]:
                    shared_key = shared_keys[file['u']][hkey]
                    if hkey in keys:
                        key = keys[hkey]
                        key = decrypt_key(base64_to_a32(key), shared_key)
                        break
            if key is not None:
                # file
                if file['t'] == 0:
                    k = (key[0] ^ key[4], key[1] ^ key[5], key[2] ^ key[6],
                         key[3] ^ key[7])
                    file['iv'] = key[4:6] + (0, 0)
                    file['meta_mac'] = key[6:8]
                # folder
                else:
                    k = key
                file['key'] = key
                file['k'] = k
                attributes = base64_url_decode(file['a'])
                attributes = decrypt_attr(attributes, k)
                file['a'] = attributes
            # other => wrong object
            elif file['k'] == '':
                file['a'] = False
        elif file['t'] == 2:
            self.root_id = file['h']
            file['a'] = {'n': 'Cloud Drive'}
        elif file['t'] == 3:
            self.inbox_id = file['h']
            file['a'] = {'n': 'Inbox'}
        elif file['t'] == 4:
            self.trashbin_id = file['h']
            file['a'] = {'n': 'Rubbish Bin'}
        return file

    def init_shared_keys(self, files, shared_keys):
        """
        Init shared key not associated with a user.
        Seems to happen when a folder is shared,
        some files are exchanged and then the
        folder is un-shared.
        Keys are stored in files['s'] and files['ok']
        """
        ok_dict = {}
        for ok_item in files['ok']:
            shared_key = decrypt_key(base64_to_a32(ok_item['k']), self.master_key)
            ok_dict[ok_item['h']] = shared_key
        for s_item in files['s']:
            if s_item['u'] not in shared_keys:
                shared_keys[s_item['u']] = {}
            if s_item['h'] in ok_dict:
                shared_keys[s_item['u']][s_item['h']] = ok_dict[s_item['h']]

    ##########################################################################
    # GET
    def find(self, filename):
        """
        Return file object from given filename
        """
        files = self.get_files()
        for file in files.items():
            if file[1]['a'] and file[1]['a']['n'] == filename:
                return file

    def get_files(self):
        """
        Get all files in account
        """
        files = self.api_request({'a': 'f', 'c': 1})
        files_dict = {}
        shared_keys = {}
        self.init_shared_keys(files, shared_keys)
        for file in files['f']:
            processed_file = self.process_file(file, shared_keys)
            #ensure each file has a name before returning
            if processed_file['a']:
                files_dict[file['h']] = processed_file
        return files_dict

    def get_upload_link(self, file):
        """
        Get a files public link inc. decrypted key
        Requires upload() response as input
        """
        if 'f' in file:
            file = file['f'][0]
            public_handle = self.api_request({'a': 'l', 'n': file['h']})
            file_key = file['k'][file['k'].index(':') + 1:]
            decrypted_key = a32_to_base64(decrypt_key(base64_to_a32(file_key),
                                                      self.master_key))
            return '{0}://{1}/#!{2}!{3}'.format(self.schema,
                                                self.domain,
                                                public_handle,
                                                decrypted_key)
        else:
            raise ValueError('''Upload() response required as input,
                            use get_link() for regular file input''')

    def get_link(self, file):
        """
        Get a file public link from given file object
        """
        file = file[1]
        if 'h' in file and 'k' in file:
            public_handle = self.api_request({'a': 'l', 'n': file['h']})
            if public_handle == -11:
                raise RequestError("Can't get a public link from that file (is this a shared file?)")
            decrypted_key = a32_to_base64(file['key'])
            return '{0}://{1}/#!{2}!{3}'.format(self.schema,
                                                self.domain,
                                                public_handle,
                                                decrypted_key)
        else:
            raise ValidationError('File id and key must be present')

    def get_user(self):
        user_data = self.api_request({'a': 'ug'})
        return user_data

    def get_node_by_type(self, type):
        """
        Get a node by it's numeric type id, e.g:
        0: file
        1: dir
        2: special: root cloud drive
        3: special: inbox
        4: special trash bin
        """
        nodes = self.get_files()
        for node in nodes.items():
            if (node[1]['t'] == type):
                return node

    def get_files_in_node(self, target):
        """
        Get all files in a given target, e.g. 4=trash
        """
        node_id = self.get_node_by_type(target)
        files = self.api_request({'a': 'f', 'c': 1})
        files_dict = {}
        shared_keys = {}
        self.init_shared_keys(files, shared_keys)
        for file in files['f']:
            processed_file = self.process_file(file, shared_keys)
            if processed_file['a'] and processed_file['p'] == node_id[0]:
                files_dict[file['h']] = processed_file
        return files_dict

    def get_id_from_public_handle(self, public_handle):
        #get node data
        #TODO fix this function
        node_data = self.api_request({'a': 'f', 'f': 1, 'p': public_handle})
        node_id = None

        #determine node id
        for i in node_data['f']:
            if i['h'] is not u'':
                node_id = i['h']
        return node_id

    def get_quota(self):
        """
        Get current remaining disk quota in MegaBytes
        """
        json_resp = self.api_request({'a': 'uq', 'xfer': 1})
        #convert bytes to megabyes
        return json_resp['mstrg'] / 1048576

    def get_balance(self):
        """
        Get account monetary balance, Pro accounts only
        """
        user_data = self.api_request({"a": "uq", "pro": 1})
        if 'balance' in user_data:
            return user_data['balance']

    ##########################################################################
    # DELETE
    def delete(self, public_handle):
        #straight delete by id
        return self.move(public_handle, 4)

    def delete_url(self, url):
        #delete a file via it's url
        path = self.parse_url(url).split('!')
        public_handle = path[0]
        file_id = self.get_id_from_public_handle(public_handle)
        return self.move(file_id, 4)

    def destroy(self, file_id):
        #delete forever by private id
        return self.api_request({'a': 'd',
                                 'n': file_id,
                                 'i': self.request_id})

    def destroy_url(self, url):
        #delete a file via it's url
        path = self.parse_url(url).split('!')
        public_handle = path[0]
        file_id = self.get_id_from_public_handle(public_handle)
        return self.destroy(file_id)

    def move(self, file_id, target):
        """
        Move a file to another parent node
        params:
        a : command
        n : node we're moving
        t : id of target parent node, moving to
        i : request id

        targets
        2 : root
        3 : inbox
        4 : trash
        """

        #determine target_node_id
        target_node_id = str(self.get_node_by_type(target)[0])
        return self.api_request({'a': 'm',
                                 'n': file_id,
                                 't': target_node_id,
                                 'i': self.request_id})

    def empty_trash(self):
        # get list of files in rubbish out
        files = self.get_files_in_node(4)

        # make a list of json
        if files != {}:
            post_list = []
            for file in files:
                post_list.append({"a": "d",
                                  "n": file,
                                  "i": self.request_id})
            return self.api_request(post_list)

    ##########################################################################
    # DOWNLOAD
    def download(self, file, dest_path=None):
        """
        Download a file by it's file object
        """
        self.download_file(None, None, file=file[1], dest_path=dest_path, is_public=False)

    def download_url(self, url, dest_path=None):
        """
        Download a file by it's public url
        """
        path = self.parse_url(url).split('!')
        file_id = path[0]
        file_key = path[1]
        self.download_file(file_id, file_key, dest_path, is_public=True)

    def download_file(self, file_handle, file_key, dest_path=None, is_public=False, file=None):
        if file is None :
            if is_public:
                file_key = base64_to_a32(file_key)
                file_data = self.api_request({'a': 'g', 'g': 1, 'p': file_handle})
            else:
                file_data = self.api_request({'a': 'g', 'g': 1, 'n': file_handle})

            k = (file_key[0] ^ file_key[4], file_key[1] ^ file_key[5],
                 file_key[2] ^ file_key[6], file_key[3] ^ file_key[7])
            iv = file_key[4:6] + (0, 0)
            meta_mac = file_key[6:8]
        else:
            file_data = self.api_request({'a': 'g', 'g': 1, 'n': file['h']})
            k = file['k']
            iv = file['iv']
            meta_mac = file['meta_mac']

        # Seems to happens sometime... When  this occurs, files are 
        # inaccessible also in the official also in the official webapp.
        # Strangely, files can come back later.
        if 'g' not in file_data:
            raise RequestError('File not accessible anymore')
        file_url = file_data['g']
        file_size = file_data['s']
        attribs = base64_url_decode(file_data['at'])
        attribs = decrypt_attr(attribs, k)
        file_name = attribs['n']
        file_name_tmp = '.megapy-%s-%s' % (int(time.time() * 1000), file_name)

        # print("downloading {0} (size: {1}), url = {2}".format(attribs['n'].encode("utf8"),
        #                                                       file_size,
        #                                                       file_url))

        input_file = requests.get(file_url, stream=True).raw

        if dest_path:
            output_file = open(dest_path + '/' + file_name_tmp, 'wb')
        else:
            output_file = open(file_name_tmp, 'wb')

        counter = Counter.new(
            128, initial_value=((iv[0] << 32) + iv[1]) << 64)
        aes = AES.new(a32_to_str(k), AES.MODE_CTR, counter=counter)

        file_mac = (0, 0, 0, 0)
        for chunk_start, chunk_size in sorted(get_chunks(file_size).items()):
            chunk = input_file.read(chunk_size)
            chunk = aes.decrypt(chunk)
            output_file.write(chunk)

            chunk_mac = [iv[0], iv[1], iv[0], iv[1]]
            for i in range(0, len(chunk), 16):
                block = chunk[i:i + 16]
                if len(block) % 16:
                    block += '\0' * (16 - (len(block) % 16))
                block = str_to_a32(block)
                chunk_mac = [
                    chunk_mac[0] ^ block[0],
                    chunk_mac[1] ^ block[1],
                    chunk_mac[2] ^ block[2],
                    chunk_mac[3] ^ block[3]]
                chunk_mac = aes_cbc_encrypt_a32(chunk_mac, k)

            file_mac = [
                file_mac[0] ^ chunk_mac[0],
                file_mac[1] ^ chunk_mac[1],
                file_mac[2] ^ chunk_mac[2],
                file_mac[3] ^ chunk_mac[3]]
            file_mac = aes_cbc_encrypt_a32(file_mac, k)
        output_file.close()

        # check mac integrity
        if (file_mac[0] ^ file_mac[1], file_mac[2] ^ file_mac[3]) != meta_mac:
            raise ValueError('Mismatched mac')

        shutil.move(file_name_tmp, file_name)

    ##########################################################################
    # UPLOAD
    def upload(self, filename, dest=None):
        #determine storage node
        if dest is None:
            #if none set, upload to cloud drive node
            if not hasattr(self, 'root_id'):
                self.get_files()
            dest = self.root_id

        #request upload url, call 'u' method
        input_file = open(filename, 'rb')
        size = os.path.getsize(filename)
        ul_url = self.api_request({'a': 'u', 's': size})['p']

        #generate random aes key (128) for file
        ul_key = [random.randint(0, 0xFFFFFFFF) for _ in range(6)]
        count = Counter.new(128, initial_value=((ul_key[4] << 32) + ul_key[5]) << 64)
        aes = AES.new(a32_to_str(ul_key[:4]), AES.MODE_CTR, counter=count)

        file_mac = [0, 0, 0, 0]
        for chunk_start, chunk_size in sorted(get_chunks(size).items()):
            chunk = input_file.read(chunk_size)

            #determine chunks mac
            chunk_mac = [ul_key[4], ul_key[5], ul_key[4], ul_key[5]]
            for i in range(0, len(chunk), 16):
                block = chunk[i:i + 16]
                if len(block) % 16:
                    block += '\0' * (16 - len(block) % 16)
                block = str_to_a32(block)
                chunk_mac = [chunk_mac[0] ^ block[0], chunk_mac[1] ^ block[1],
                             chunk_mac[2] ^ block[2],
                             chunk_mac[3] ^ block[3]]
                chunk_mac = aes_cbc_encrypt_a32(chunk_mac, ul_key[:4])

            #our files mac
            file_mac = [file_mac[0] ^ chunk_mac[0], file_mac[1] ^ chunk_mac[1],
                        file_mac[2] ^ chunk_mac[2],
                        file_mac[3] ^ chunk_mac[3]]
            file_mac = aes_cbc_encrypt_a32(file_mac, ul_key[:4])

            #encrypt file and upload
            chunk = aes.encrypt(chunk)
            output_file = requests.post(ul_url + "/" + str(chunk_start),
                                        data=chunk, timeout=self.timeout)
            completion_file_handle = output_file.text

        #determine meta mac
        meta_mac = (file_mac[0] ^ file_mac[1], file_mac[2] ^ file_mac[3])

        attribs = {'n': os.path.basename(filename)}
        encrypt_attribs = base64_url_encode(encrypt_attr(attribs, ul_key[:4]))
        key = [ul_key[0] ^ ul_key[4], ul_key[1] ^ ul_key[5],
               ul_key[2] ^ meta_mac[0], ul_key[3] ^ meta_mac[1],
               ul_key[4], ul_key[5], meta_mac[0], meta_mac[1]]
        encrypted_key = a32_to_base64(encrypt_key(key, self.master_key))
        #update attributes
        data = self.api_request({'a': 'p', 't': dest, 'n': [{
                                'h': completion_file_handle,
                                't': 0,
                                'a': encrypt_attribs,
                                'k': encrypted_key}]})
        #close input file and return API msg
        input_file.close()
        return data

    def create_folder(self, name, dest=None):
        #determine storage node
        if dest is None:
            #if none set, upload to cloud drive node
            if not hasattr(self, 'root_id'):
                self.get_files()
            dest = self.root_id

        #generate random aes key (128) for folder
        ul_key = [random.randint(0, 0xFFFFFFFF) for _ in range(6)]

        #encrypt attribs
        attribs = {'n': name}
        encrypt_attribs = base64_url_encode(encrypt_attr(attribs, ul_key[:4]))
        encrypted_key = a32_to_base64(encrypt_key(ul_key[:4], self.master_key))

        #update attributes
        data = self.api_request({'a': 'p',
                                 't': dest,
                                 'n': [{
                                     'h': 'xxxxxxxx',
                                     't': 1,
                                     'a': encrypt_attribs,
                                     'k': encrypted_key}
                                 ],
                                 'i': self.request_id})
        #return API msg
        return data