python: Import improved python bindings.

This commit imports the python bindings from:
    https://github.com/poljar/python-olm

The bindings are imported at commit c44b145818520d69eaaa350fb95afcb846125e0f

Minor modifications were made while importing:
    - Removed travis config
    - Removed Arch Linux PKGBUILD
    - Removed the html docs, they can be rebuild by running make html in
      the docs folder
    - Slightly modified the README

The new bindings feature some improvements over the old ones:
    - Python 2 and 3 support
    - Automatic memory management
    - Automatic memory clearing before it is freed
    - Type signatures via the python typing module
    - Full test coverage
    - Properties are utilized where it makes sense (e.g. account.id)

Signed-off-by: Damir Jelić <poljar@termina.org.uk>

1 files changed, 91 insertions, 0 deletions

diff --git a/python/olm/utility.py b/python/olm/utility.py
new file mode 100644
index 0000000..838cf3f
--- /dev/null
+++ b/python/olm/utility.py
@@ -0,0 +1,91 @@
+# -*- coding: utf-8 -*-
+# libolm python bindings
+# Copyright © 2015-2017 OpenMarket Ltd
+# Copyright © 2018 Damir Jelić <poljar@termina.org.uk>
+"""libolm Utility module.
+
+This module contains utilities for olm.
+It only contains the ed25519_verify function for signature verification.
+
+Examples:
+    >>> alice = Account()
+
+    >>> message = "Test"
+    >>> signature = alice.sign(message)
+    >>> signing_key = alice.identity_keys["ed25519"]
+
+    >>> ed25519_verify(signing_key, message, signature)
+
+"""
+
+# pylint: disable=redefined-builtin,unused-import
+from typing import AnyStr, Type
+
+# pylint: disable=no-name-in-module
+from _libolm import ffi, lib  # type: ignore
+
+from ._compat import to_bytes
+from ._finalize import track_for_finalization
+
+
+def _clear_utility(utility):  # pragma: no cover
+    # type: (ffi.cdata) -> None
+    lib.olm_clear_utility(utility)
+
+
+class OlmVerifyError(Exception):
+    """libolm signature verification exception."""
+
+
+class _Utility(object):
+    # pylint: disable=too-few-public-methods
+    """libolm Utility class."""
+
+    _buf = None
+    _utility = None
+
+    @classmethod
+    def _allocate(cls):
+        # type: (Type[_Utility]) -> None
+        cls._buf = ffi.new("char[]", lib.olm_utility_size())
+        cls._utility = lib.olm_utility(cls._buf)
+        track_for_finalization(cls, cls._utility, _clear_utility)
+
+    @classmethod
+    def _check_error(cls, ret):
+        # type: (int) -> None
+        if ret != lib.olm_error():
+            return
+
+        raise OlmVerifyError("{}".format(
+            ffi.string(lib.olm_utility_last_error(
+                cls._utility)).decode("utf-8")))
+
+    @classmethod
+    def _ed25519_verify(cls, key, message, signature):
+        # type: (Type[_Utility], AnyStr, AnyStr, AnyStr) -> None
+        if not cls._utility:
+            cls._allocate()
+
+        byte_key = to_bytes(key)
+        byte_message = to_bytes(message)
+        byte_signature = to_bytes(signature)
+
+        cls._check_error(
+            lib.olm_ed25519_verify(cls._utility, byte_key, len(byte_key),
+                                   byte_message, len(byte_message),
+                                   byte_signature, len(byte_signature)))
+
+
+def ed25519_verify(key, message, signature):
+    # type: (AnyStr, AnyStr, AnyStr) -> None
+    """Verify an ed25519 signature.
+
+    Raises an OlmVerifyError if verification fails.
+
+    Args:
+        key(str): The ed25519 public key used for signing.
+        message(str): The signed message.
+        signature(bytes): The message signature.
+    """
+    return _Utility._ed25519_verify(key, message, signature)