Merge pull request #42 from matrix-org/rav/megolm_export

Export and import of megolm session data

4 files changed, 94 insertions, 5 deletions

diff --git a/python/.gitignore b/python/.gitignore
index b8ca4f7..a3d197d 100644
--- a/python/.gitignore
+++ b/python/.gitignore
@@ -2,3 +2,4 @@
 /*.account
 /*.session
 /*.group_session
+/group_message
diff --git a/python/olm/__main__.py b/python/olm/__main__.py
index eb76301..5f78f76 100755
--- a/python/olm/__main__.py
+++ b/python/olm/__main__.py
@@ -268,6 +268,19 @@ def build_arg_parser():
                                default=sys.stdin)
     inbound_group.set_defaults(func=do_inbound_group)
 
+    import_inbound_group = commands.add_parser(
+        "import_inbound_group",
+        help="Create an inbound group session based an exported inbound group"
+    )
+    import_inbound_group.add_argument("session_file", help="Local inbound group session file")
+    import_inbound_group.add_argument(
+        "export_file",
+        help="File to read credentials from (default stdin)",
+        type=argparse.FileType('r'), nargs='?',
+        default=sys.stdin,
+    )
+    import_inbound_group.set_defaults(func=do_import_inbound_group)
+
     group_decrypt = commands.add_parser("group_decrypt", help="Decrypt a group message")
     group_decrypt.add_argument("session_file", help="Local inbound group session file")
     group_decrypt.add_argument("message_file", help="Message file (default stdin)",
@@ -277,6 +290,27 @@ def build_arg_parser():
                                type=argparse.FileType('wb'), nargs='?',
                                default=sys.stdout)
     group_decrypt.set_defaults(func=do_group_decrypt)
+
+
+    export_inbound_group = commands.add_parser(
+        "export_inbound_group",
+        help="Export the keys for an inbound group session",
+    )
+    export_inbound_group.add_argument(
+        "session_file", help="Local inbound group session file",
+    )
+    export_inbound_group.add_argument(
+        "export_file", help="File to export to (default stdout)",
+        type=argparse.FileType('w'), nargs='?',
+        default=sys.stdout,
+    )
+    export_inbound_group.add_argument(
+        "--message_index",
+        help="Index to export session at. Defaults to the earliest known index",
+        type=int,
+    )
+    export_inbound_group.set_defaults(func=do_export_inbound_group)
+
     return parser
 
 def do_outbound_group(args):
@@ -324,6 +358,19 @@ def do_inbound_group(args):
     with open(args.session_file, "wb") as f:
         f.write(session.pickle(args.key))
 
+def do_import_inbound_group(args):
+    if os.path.exists(args.session_file):
+        sys.stderr.write("Session %r file already exists\n" % (
+            args.session_file,
+        ))
+        sys.exit(1)
+    data = args.export_file.read().translate(None, "\r\n")
+
+    session = InboundGroupSession()
+    session.import_session(data)
+    with open(args.session_file, "wb") as f:
+        f.write(session.pickle(args.key))
+
 def do_group_decrypt(args):
     session = InboundGroupSession()
     session.unpickle(args.key, read_base64_file(args.session_file))
@@ -333,6 +380,15 @@ def do_group_decrypt(args):
         f.write(session.pickle(args.key))
     args.plaintext_file.write(plaintext)
 
+def do_export_inbound_group(args):
+    session = InboundGroupSession()
+    session.unpickle(args.key, read_base64_file(args.session_file))
+    index = args.message_index
+    if index is None:
+        # default to first known index
+        index = session.first_known_index()
+    args.export_file.write(session.export_session(index))
+
 if __name__ == '__main__':
     parser = build_arg_parser()
     args = parser.parse_args()
diff --git a/python/olm/inbound_group_session.py b/python/olm/inbound_group_session.py
index 27a569c..4390b34 100644
--- a/python/olm/inbound_group_session.py
+++ b/python/olm/inbound_group_session.py
@@ -37,6 +37,10 @@ inbound_group_session_function(
 )
 
 inbound_group_session_function(
+    lib.olm_import_inbound_group_session, c_void_p, c_size_t
+)
+
+inbound_group_session_function(
     lib.olm_group_decrypt_max_plaintext_length, c_void_p, c_size_t
 )
 inbound_group_session_function(
@@ -49,6 +53,13 @@ inbound_group_session_function(
 inbound_group_session_function(lib.olm_inbound_group_session_id_length)
 inbound_group_session_function(lib.olm_inbound_group_session_id, c_void_p, c_size_t)
 
+lib.olm_inbound_group_session_first_known_index.argtypes = (c_void_p,)
+lib.olm_inbound_group_session_first_known_index.restypes = c_uint32
+
+inbound_group_session_function(lib.olm_export_inbound_group_session_length)
+inbound_group_session_function(lib.olm_export_inbound_group_session, c_void_p, c_size_t, c_uint32)
+
+
 class InboundGroupSession(object):
     def __init__(self):
         self.buf = create_string_buffer(lib.olm_inbound_group_session_size())
@@ -76,6 +87,12 @@ class InboundGroupSession(object):
             self.ptr, key_buffer, len(session_key)
         )
 
+    def import_session(self, session_key):
+        key_buffer = create_string_buffer(session_key)
+        lib.olm_import_inbound_group_session(
+            self.ptr, key_buffer, len(session_key)
+        )
+
     def decrypt(self, message):
         message_buffer = create_string_buffer(message)
         max_plaintext_length = lib.olm_group_decrypt_max_plaintext_length(
@@ -95,5 +112,15 @@ class InboundGroupSession(object):
     def session_id(self):
         id_length = lib.olm_inbound_group_session_id_length(self.ptr)
         id_buffer = create_string_buffer(id_length)
-        lib.olm_inbound_group_session_id(self.ptr, id_buffer, id_length);
+        lib.olm_inbound_group_session_id(self.ptr, id_buffer, id_length)
         return id_buffer.raw
+
+    def first_known_index(self):
+        return lib.olm_inbound_group_session_first_known_index(self.ptr)
+
+    def export_session(self, message_index):
+        length = lib.olm_export_inbound_group_session_length(self.ptr)
+        buffer = create_string_buffer(length)
+        lib.olm_export_inbound_group_session(self.ptr, buffer, length,
+                                             message_index)
+        return buffer.raw
diff --git a/python/test_olm.sh b/python/test_olm.sh
index 989e166..7c90daf 100755
--- a/python/test_olm.sh
+++ b/python/test_olm.sh
@@ -10,10 +10,11 @@ ALICE_GROUP_SESSION=alice.group_session
 BOB_ACCOUNT=bob.account
 BOB_SESSION=bob.session
 BOB_GROUP_SESSION=bob.group_session
+CHARLIE_GROUP_SESSION=charlie.group_session
 
-rm $ALICE_ACCOUNT $BOB_ACCOUNT
-rm $ALICE_SESSION $BOB_SESSION
-rm $ALICE_GROUP_SESSION $BOB_GROUP_SESSION
+rm -f $ALICE_ACCOUNT $BOB_ACCOUNT
+rm -f $ALICE_SESSION $BOB_SESSION
+rm -f $ALICE_GROUP_SESSION $BOB_GROUP_SESSION $CHARLIE_GROUP_SESSION
 
 $OLM create_account $ALICE_ACCOUNT
 $OLM create_account $BOB_ACCOUNT
@@ -31,4 +32,8 @@ echo "Hello world" | $OLM encrypt $ALICE_SESSION - - | $OLM inbound $BOB_ACCOUNT
 
 $OLM outbound_group $ALICE_GROUP_SESSION
 $OLM group_credentials $ALICE_GROUP_SESSION | $OLM inbound_group $BOB_GROUP_SESSION
-echo "Hello group" | $OLM group_encrypt $ALICE_GROUP_SESSION - - | $OLM group_decrypt $BOB_GROUP_SESSION
+echo "Hello group" | $OLM group_encrypt $ALICE_GROUP_SESSION - group_message
+$OLM group_decrypt $BOB_GROUP_SESSION group_message
+
+$OLM export_inbound_group $BOB_GROUP_SESSION | $OLM import_inbound_group $CHARLIE_GROUP_SESSION
+$OLM group_decrypt $CHARLIE_GROUP_SESSION group_message