1 files changed, 157 insertions, 0 deletions
diff --git a/backends/leap.py b/backends/leap.py
new file mode 100644
index 00000000..2c815632
--- /dev/null
+++ b/backends/leap.py
@@ -0,0 +1,157 @@
+try:
+    import simplejson as json
+except ImportError:
+    import json  # noqa
+
+from u1db import Document
+from u1db.remote.http_target import HTTPSyncTarget
+from u1db.remote.http_database import HTTPDatabase
+import base64
+
+
+class NoDefaultKey(Exception):
+    pass
+
+
+class LeapDocument(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, default_key=None, gpg_wrapper=None):
+        super(LeapDocument, self).__init__(doc_id, rev, json, has_conflicts)
+        # we might want to get already initialized wrappers for testing.
+        if gpg_wrapper is None:
+            self._gpg = GPGWrapper()
+        else:
+            self._gpg = gpg_wrapper
+        if encrypted_json:
+            self.set_encrypted_json(encrypted_json)
+        self._default_key = default_key
+
+    def get_encrypted_json(self):
+        """
+        Returns document's json serialization encrypted with user's public key.
+        """
+        if self._default_key is None:
+            raise NoDefaultKey()
+        cyphertext = self._gpg.encrypt(self.get_json(),
+                                       self._default_key,
+                                       always_trust = True)
+                                       # TODO: always trust?
+        return json.dumps({'cyphertext' : str(cyphertext)})
+
+    def set_encrypted_json(self, encrypted_json):
+        """
+        Set document's content based on encrypted version of json string.
+        """
+        cyphertext = json.loads(encrypted_json)['cyphertext']
+        plaintext = str(self._gpg.decrypt(cyphertext))
+        return self.set_json(plaintext)
+
+
+class LeapDatabase(HTTPDatabase):
+    """Implement the HTTP remote database API to a Leap server."""
+
+    @staticmethod
+    def open_database(url, create):
+        db = LeapDatabase(url)
+        db.open(create)
+        return db
+
+    @staticmethod
+    def delete_database(url):
+        db = LeapDatabase(url)
+        db._delete()
+        db.close()
+
+    def get_sync_target(self):
+        st = LeapSyncTarget(self._url.geturl())
+        st._creds = self._creds
+        return st
+
+
+class LeapSyncTarget(HTTPSyncTarget):
+
+    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)
+                doc = LeapDocument(entry['id'], entry['rev'],
+                                   encrypted_json=entry['content'])
+                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:
+            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']