do not cache endpoints

Caching these would have allowed a malicious or buggy
auth/token_endpoint combination to give you credentials for another
user's domain name.

CHANGELOG.md

@@ -1,6 +1,17 @@
 # Change Log
 All notable changes to this project will be documented in this file.
 
+## 0.2.2
+## Changed
+- Fix vulnerability; re-discover the authorization_endpoint and
+  token_endpoint at each stage in the flow. Prevents a buggy or
+  malicious authorization_endpoint from giving you credentials for
+  another user's domain name.
+
+## 0.2.1 - 2015-02-07
+## Changed
+- Updated setup.py, no functional changes
+
 ## 0.2.0 - 2015-02-07
 ### Changed
 - Started keeping a changelog!

flask_micropub.py

@@ -121,10 +121,6 @@ class MicropubClient:
 
         csrf_token = uuid.uuid4().hex
         flask.session['_micropub_csrf_token'] = csrf_token
-        # save the endpoints so we don't have to scrape the target page again
-        # right awway
-        flask.session['_micropub_endpoints'] = (
-            auth_url, token_url, micropub_url)
 
         auth_params = {
             'me': me,
@@ -165,6 +161,7 @@ class MicropubClient:
     def _handle_authenticate_response(self):
         code = flask.request.args.get('code')
         state = flask.request.args.get('state')
+        me = flask.request.args.get('me')
         redirect_uri = flask.url_for(flask.request.endpoint, _external=True)
 
         if state and '|' in state:
@@ -180,11 +177,7 @@ class MicropubClient:
             return AuthResponse(
                 next_url=next_url, error='mismatched CSRF token')
 
-        if '_micropub_endpoints' in flask.session:
-            auth_url = flask.session['_micropub_endpoints'][0]
-        else:
-            auth_url = self._discover_endpoints(
-                flask.request.args.get('me'))[0]
+        auth_url = self._discover_endpoints(me)[0]
 
         if not auth_url:
             return AuthResponse(
@@ -227,16 +220,13 @@ class MicropubClient:
         authenticate_response = self._handle_authenticate_response()
         code = flask.request.args.get('code')
         state = flask.request.args.get('state')
+        me = flask.request.args.get('me')
         redirect_uri = flask.url_for(flask.request.endpoint, _external=True)
 
         if authenticate_response.error:
             return authenticate_response
 
-        if '_micropub_endpoints' in flask.session:
-            _, token_url, micropub_url = flask.session['_micropub_endpoints']
-        else:
-            _, token_url, micropub_url = self._discover_endpoints(
-                flask.request.args.get('me'))
+        token_url, micropub_url = self._discover_endpoints(me)[1:]
 
         if not token_url or not micropub_url:
             # successfully auth'ed user, no micropub endpoint

setup.py

@@ -11,7 +11,7 @@ from setuptools import setup
 
 setup(
     name='Flask-Micropub',
-    version='0.2.0',
+    version='0.2.2',
     url='https://github.com/kylewm/flask-micropub/',
     license='BSD',
     author='Kyle Mahan',