diff options
Diffstat (limited to 'soledad/backends/leap_backend.py')
| -rw-r--r-- | soledad/backends/leap_backend.py | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/soledad/backends/leap_backend.py b/soledad/backends/leap_backend.py new file mode 100644 index 00000000..a37f9d25 --- /dev/null +++ b/soledad/backends/leap_backend.py @@ -0,0 +1,224 @@ +""" +A U1DB backend that encrypts data before sending to server and decrypts after +receiving. +""" + +try: + import simplejson as json +except ImportError: + import json # noqa + +from u1db import Document +from u1db.remote import utils +from u1db.remote.http_target import HTTPSyncTarget +from u1db.remote.http_database import HTTPDatabase +from u1db.errors import BrokenSyncStream + +import uuid + + +class NoDefaultKey(Exception): + """ + Exception to signal that there's no default OpenPGP key configured. + """ + pass + + +class NoSoledadInstance(Exception): + """ + Exception to signal that no Soledad instance was found. + """ + pass + + +class DocumentNotEncrypted(Exception): + """ + Exception to signal failures in document encryption. + """ + pass + + +class LeapDocument(Document): + """ + Encryptable and syncable document. + + LEAP Documents are standard u1db documents with cabability of returning an + encrypted version of the document json string as well as setting document + content based on an encrypted version of json string. + """ + + def __init__(self, doc_id=None, rev=None, json='{}', has_conflicts=False, + encrypted_json=None, soledad=None, syncable=True): + super(LeapDocument, self).__init__(doc_id, rev, json, has_conflicts) + self._soledad = soledad + self._syncable = syncable + if encrypted_json: + self.set_encrypted_json(encrypted_json) + + def get_encrypted_content(self): + """ + Return an encrypted JSON serialization of document's contents. + """ + if not self._soledad: + raise NoSoledadInstance() + return self._soledad.encrypt_symmetric(self.doc_id, + self.get_json()) + + def set_encrypted_content(self, cyphertext): + """ + Set document's content based on an encrypted JSON serialization of + contents. + """ + plaintext = self._soledad.decrypt_symmetric(self.doc_id, cyphertext) + return self.set_json(plaintext) + + def get_encrypted_json(self): + """ + Return a valid JSON string containing document's content encrypted to + the user's public key. + """ + return json.dumps({'_encrypted_json': self.get_encrypted_content()}) + + def set_encrypted_json(self, encrypted_json): + """ + Set document's content based on a valid JSON string containing the + encrypted document's contents. + """ + if not self._soledad: + raise NoSoledadInstance() + cyphertext = json.loads(encrypted_json)['_encrypted_json'] + self.set_encrypted_content(cyphertext) + + def _get_syncable(self): + return self._syncable + + def _set_syncable(self, syncable=True): + self._syncable = syncable + + syncable = property( + _get_syncable, + _set_syncable, + doc="Determine if document should be synced with server." + ) + + # Returning the revision as string solves the following exception in + # Twisted web: + # exceptions.TypeError: Can only pass-through bytes on Python 2 + def _get_rev(self): + if self._rev is None: + return None + return str(self._rev) + + def _set_rev(self, rev): + self._rev = rev + + rev = property( + _get_rev, + _set_rev, + doc="Wrapper to ensure `doc.rev` is always returned as bytes.") + + +class LeapSyncTarget(HTTPSyncTarget): + """ + A SyncTarget that encrypts data before sending and decrypts data after + receiving. + """ + + def __init__(self, url, creds=None, soledad=None): + super(LeapSyncTarget, self).__init__(url, creds) + self._soledad = soledad + + def _parse_sync_stream(self, data, return_doc_cb, ensure_callback=None): + """ + Does the same as parent's method but ensures incoming content will be + decrypted. + """ + parts = data.splitlines() # one at a time + if not parts or parts[0] != '[': + raise BrokenSyncStream + data = parts[1:-1] + comma = False + if data: + line, comma = utils.check_and_strip_comma(data[0]) + res = json.loads(line) + if ensure_callback and 'replica_uid' in res: + ensure_callback(res['replica_uid']) + for entry in data[1:]: + if not comma: # missing in between comma + raise BrokenSyncStream + line, comma = utils.check_and_strip_comma(entry) + entry = json.loads(line) + # decrypt after receiving from server. + if not self._soledad: + raise NoSoledadInstance() + enc_json = json.loads(entry['content'])['_encrypted_json'] + if not self._soledad.is_encrypted_sym(enc_json): + raise DocumentNotEncrypted( + "Incoming document from sync is not encrypted.") + doc = LeapDocument(entry['id'], entry['rev'], + encrypted_json=entry['content'], + soledad=self._soledad) + return_doc_cb(doc, entry['gen'], entry['trans_id']) + if parts[-1] != ']': + try: + partdic = json.loads(parts[-1]) + except ValueError: + pass + else: + if isinstance(partdic, dict): + self._error(partdic) + raise BrokenSyncStream + if not data or comma: # no entries or bad extra comma + raise BrokenSyncStream + return res + + def sync_exchange(self, docs_by_generations, source_replica_uid, + last_known_generation, last_known_trans_id, + return_doc_cb, ensure_callback=None): + """ + Does the same as parent's method but encrypts content before syncing. + """ + self._ensure_connection() + if self._trace_hook: # for tests + self._trace_hook('sync_exchange') + url = '%s/sync-from/%s' % (self._url.path, source_replica_uid) + self._conn.putrequest('POST', url) + self._conn.putheader('content-type', 'application/x-u1db-sync-stream') + for header_name, header_value in self._sign_request('POST', url, {}): + self._conn.putheader(header_name, header_value) + entries = ['['] + size = 1 + + def prepare(**dic): + entry = comma + '\r\n' + json.dumps(dic) + entries.append(entry) + return len(entry) + + comma = '' + size += prepare( + last_known_generation=last_known_generation, + last_known_trans_id=last_known_trans_id, + ensure=ensure_callback is not None) + comma = ',' + for doc, gen, trans_id in docs_by_generations: + if doc.syncable: + # encrypt and verify before sending to server. + enc_json = json.loads( + doc.get_encrypted_json())['_encrypted_json'] + if not self._soledad.is_encrypted_sym(enc_json): + raise DocumentNotEncrypted( + "Could not encrypt document before sync.") + size += prepare(id=doc.doc_id, rev=doc.rev, + content=doc.get_encrypted_json(), + gen=gen, trans_id=trans_id) + entries.append('\r\n]') + size += len(entries[-1]) + self._conn.putheader('content-length', str(size)) + self._conn.endheaders() + for entry in entries: + self._conn.send(entry) + entries = None + data, _ = self._response() + res = self._parse_sync_stream(data, return_doc_cb, ensure_callback) + data = None + return res['new_generation'], res['new_transaction_id'] |