diff options
Diffstat (limited to 'common/src/leap/soledad/common/couch/state.py')
| -rw-r--r-- | common/src/leap/soledad/common/couch/state.py | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/common/src/leap/soledad/common/couch/state.py b/common/src/leap/soledad/common/couch/state.py new file mode 100644 index 00000000..4f07c105 --- /dev/null +++ b/common/src/leap/soledad/common/couch/state.py @@ -0,0 +1,160 @@ +# -*- coding: utf-8 -*- +# state.py +# Copyright (C) 2015 LEAP +# +# This program is free software: you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation, either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see <http://www.gnu.org/licenses/>. +""" +Server state using CouchDatabase as backend. +""" +import re +import logging +import time +from urlparse import urljoin +from hashlib import sha512 + +from u1db.remote.server_state import ServerState +from leap.soledad.common.command import exec_validated_cmd +from leap.soledad.common.couch import CouchDatabase +from leap.soledad.common.couch import couch_server +from u1db.errors import Unauthorized + + +logger = logging.getLogger(__name__) + + +def is_db_name_valid(name): + """ + Validate a user database using a regular expression. + + :param name: database name. + :type name: str + + :return: boolean for name vailidity + :rtype: bool + """ + db_name_regex = "^user-[a-f0-9]+$" + return re.match(db_name_regex, name) is not None + + +class CouchServerState(ServerState): + + """ + Inteface of the WSGI server with the CouchDB backend. + """ + + TOKENS_DB_PREFIX = "tokens_" + TOKENS_DB_EXPIRE = 30 * 24 * 3600 # 30 days in seconds + TOKENS_TYPE_KEY = "type" + TOKENS_TYPE_DEF = "Token" + TOKENS_USER_ID_KEY = "user_id" + + def __init__(self, couch_url, create_cmd=None): + """ + Initialize the couch server state. + + :param couch_url: The URL for the couch database. + :type couch_url: str + """ + self.couch_url = couch_url + self.create_cmd = create_cmd + + def open_database(self, dbname): + """ + Open a couch database. + + :param dbname: The name of the database to open. + :type dbname: str + + :return: The SoledadBackend object. + :rtype: SoledadBackend + """ + url = urljoin(self.couch_url, dbname) + db = CouchDatabase.open_database(url, create=False, ensure_ddocs=False) + return db + + def ensure_database(self, dbname): + """ + Ensure couch database exists. + + :param dbname: The name of the database to ensure. + :type dbname: str + + :raise Unauthorized: If disabled or other error was raised. + + :return: The SoledadBackend object and its replica_uid. + :rtype: (SoledadBackend, str) + """ + if not self.create_cmd: + raise Unauthorized() + else: + code, out = exec_validated_cmd(self.create_cmd, dbname, + validator=is_db_name_valid) + if code is not 0: + logger.error(""" + Error while creating database (%s) with (%s) command. + Output: %s + Exit code: %d + """ % (dbname, self.create_cmd, out, code)) + raise Unauthorized() + db = self.open_database(dbname) + return db, db.replica_uid + + def delete_database(self, dbname): + """ + Delete couch database. + + :param dbname: The name of the database to delete. + :type dbname: str + + :raise Unauthorized: Always, because Soledad server is not allowed to + delete databases. + """ + raise Unauthorized() + + def verify_token(self, uuid, token): + """ + Query couchdb to decide if C{token} is valid for C{uuid}. + + @param uuid: The user uuid. + @type uuid: str + @param token: The token. + @type token: str + """ + with couch_server(self.couch_url) as server: + # the tokens db rotates every 30 days, and the current db name is + # "tokens_NNN", where NNN is the number of seconds since epoch + # divide dby the rotate period in seconds. When rotating, old and + # new tokens db coexist during a certain window of time and valid + # tokens are replicated from the old db to the new one. See: + # https://leap.se/code/issues/6785 + dbname = self._tokens_dbname() + db = server[dbname] + # lookup key is a hash of the token to prevent timing attacks. + token = db.get(sha512(token).hexdigest()) + if token is None: + return False + # we compare uuid hashes to avoid possible timing attacks that + # might exploit python's builtin comparison operator behaviour, + # which fails immediatelly when non-matching bytes are found. + couch_uuid_hash = sha512(token[self.TOKENS_USER_ID_KEY]).digest() + req_uuid_hash = sha512(uuid).digest() + if token[self.TOKENS_TYPE_KEY] != self.TOKENS_TYPE_DEF \ + or couch_uuid_hash != req_uuid_hash: + return False + return True + + def _tokens_dbname(self): + dbname = self.TOKENS_DB_PREFIX + \ + str(int(time.time() / self.TOKENS_DB_EXPIRE)) + return dbname |