All: Implement a token handler

This implements a token handler for OAuth tokens. Clients can use the SetTokenHandler
function in exports to set a token handler.

It needs two arguments, a getter and a setter. The getter is a callback with three arguments:
- The server to get the tokens for, in types.server.current as JSON
- The output buffer
- The output buffer maximum length

The tokens should be written to the output buffer with maximum
length. The type should be types.server.Tokens and be marshalled as
JSON. If no tokens are available, leave the output buffer intact

The token setter is a callback with two arguments:
- The server for which to set the tokens for, in types.server.Current as JSON
- The tokens, defined in types.server.Tokens as JSON

Breaking changes:
- No more tokens as arguments, was already deprecated in previous commits
- Tokens are no longer returned in types.server.Configuration

3 files changed, 54 insertions, 12 deletions

diff --git a/wrappers/python/eduvpn_common/loader.py b/wrappers/python/eduvpn_common/loader.py
index 961b569..1a172af 100644
--- a/wrappers/python/eduvpn_common/loader.py
+++ b/wrappers/python/eduvpn_common/loader.py
@@ -4,7 +4,7 @@ from collections import defaultdict
 from ctypes import CDLL, c_char_p, c_int, c_void_p, cdll
 
 from eduvpn_common import __version__
-from eduvpn_common.types import BoolError, DataError, ReadRxBytes, VPNStateChange
+from eduvpn_common.types import BoolError, DataError, ReadRxBytes, TokenGetter, TokenSetter, VPNStateChange
 
 
 def load_lib() -> CDLL:
@@ -88,6 +88,7 @@ def initialize_functions(lib: CDLL) -> None:
         c_int,
     ], c_void_p
     lib.RenewSession.argtypes, lib.RenewSession.restype = [c_int], c_void_p
+    lib.SetTokenHandler.argtypes, lib.SetTokenHandler.restype = [TokenGetter, TokenSetter], c_void_p
     lib.Cleanup.argtypes, lib.Cleanup.restype = [c_int], c_void_p
     lib.SetProfileID.argtypes, lib.SetProfileID.restype = [c_char_p], c_void_p
     lib.CookieNew.argtypes, lib.CookieNew.restype = [], c_int
diff --git a/wrappers/python/eduvpn_common/main.py b/wrappers/python/eduvpn_common/main.py
index b10e641..5d08ba9 100644
--- a/wrappers/python/eduvpn_common/main.py
+++ b/wrappers/python/eduvpn_common/main.py
@@ -1,8 +1,9 @@
+import ctypes
 from enum import IntEnum
 from typing import Any, Callable, Iterator, Optional
 
 from eduvpn_common.loader import initialize_functions, load_lib
-from eduvpn_common.types import ReadRxBytes, VPNStateChange, decode_res, encode_args
+from eduvpn_common.types import ReadRxBytes, TokenGetter, TokenSetter, VPNStateChange, decode_res, encode_args
 
 
 class WrappedError(Exception):
@@ -56,6 +57,9 @@ class EduVPN(object):
         self.version = version
         self.config_directory = config_directory
         self.jar = Jar(lambda x: self.go_function(self.lib.CookieCancel, x))
+        self.callback = None
+        self.token_setter = None
+        self.token_getter = None
 
         # Load the library
         self.lib = load_lib()
@@ -88,8 +92,8 @@ class EduVPN(object):
         This removes the object from internal bookkeeping and saves the configuration
         """
         self.go_function(self.lib.Deregister)
-        global callback_object
-        callback_object = None
+        global global_object
+        global_object = None
 
     def register(self, handler: Optional[Callable] = None, debug: bool = False) -> None:
         """Register the Go shared library.
@@ -99,10 +103,11 @@ class EduVPN(object):
         :param debug: bool:  (Default value = False): Whether or not we want to enable debug logging
 
         """
-        global callback_object
-        if callback_object is not None:
+        global global_object
+        if global_object is not None:
             raise Exception("Already registered")
-        callback_object = handler
+        self.callback = handler
+        global_object = self
         register_err = self.go_function(
             self.lib.Register,
             self.name,
@@ -244,6 +249,14 @@ class EduVPN(object):
         if location_err:
             forwardError(location_err)
 
+    def set_token_handler(self, getter: Callable, setter: Callable) -> None:
+        self.token_setter = setter
+        self.token_getter = getter
+        handler_err = self.go_function(self.lib.SetTokenHandler, token_getter, token_setter)
+
+        if handler_err:
+            forwardError(handler_err)
+
     def cookie_reply(self, cookie: int, data: str) -> None:
         """Reply with the given cookie and data"""
         cookie_err = self.go_function(self.lib.CookieReply, cookie, data)
@@ -289,8 +302,30 @@ class EduVPN(object):
         self.jar.cancel()
 
 
-callback_object: Optional[Callable] = None
+global_object: Optional[EduVPN] = None
 
+@TokenSetter
+def token_setter(server: ctypes.c_char_p, tokens: ctypes.c_char_p):
+    global global_object
+    if global_object is None:
+        return
+    if global_object.token_setter is None:
+        return 0
+    global_object.token_setter(server.decode(), tokens.decode())
+
+@TokenGetter
+def token_getter(server: ctypes.c_char_p, buf: ctypes.c_char_p, size: ctypes.c_size_t):
+    global global_object
+    if global_object is None:
+        return
+    if global_object.token_getter is None:
+        return
+    got = global_object.token_getter(server.decode())
+    if got is None:
+        return
+
+    outbuf = ctypes.cast(buf, ctypes.POINTER(ctypes.c_char * size))
+    outbuf.contents.value = got.encode("utf-8")
 
 @VPNStateChange
 def state_callback(old_state: int, new_state: int, data: str) -> int:
@@ -302,9 +337,12 @@ def state_callback(old_state: int, new_state: int, data: str) -> int:
 
     :meta private:
     """
-    if callback_object is None:
+    global global_object
+    if global_object is None:
+        return 0
+    if global_object.callback is None:
         return 0
-    handled = callback_object(old_state, new_state, data.decode("utf-8"))
+    handled = global_object.callback(old_state, new_state, data.decode("utf-8"))
     if handled:
         return 1
     return 0
diff --git a/wrappers/python/eduvpn_common/types.py b/wrappers/python/eduvpn_common/types.py
index 1eba468..f83e710 100644
--- a/wrappers/python/eduvpn_common/types.py
+++ b/wrappers/python/eduvpn_common/types.py
@@ -1,10 +1,13 @@
 from ctypes import (
     CDLL,
     CFUNCTYPE,
+    POINTER,
     Structure,
+    c_char,
     c_char_p,
     c_int,
     c_ulonglong,
+    c_size_t,
     c_void_p,
     cast,
 )
@@ -32,8 +35,8 @@ class BoolError(Structure):
 # The type for a Go state change callback
 VPNStateChange = CFUNCTYPE(c_int, c_int, c_int, c_char_p)
 ReadRxBytes = CFUNCTYPE(c_ulonglong)
-UpdateToken = CFUNCTYPE(None, c_char_p, c_void_p, c_void_p)
-
+TokenGetter = CFUNCTYPE(c_void_p, c_char_p, POINTER(c_char), c_size_t)
+TokenSetter = CFUNCTYPE(c_void_p, c_char_p, c_char_p)
 
 def encode_args(args: List[Any], types: List[Any]) -> Iterator[Any]:
     """Encode the arguments ready to be used by the Go library