Make discovery more RFC-conformant (#585)

* Make discovery more RFC-conformant

Fix #584

CHANGELOG.rst

@@ -14,6 +14,7 @@ Version 0.16.0
 
 - Strip ``METHOD:PUBLISH`` added by some calendar providers.
 - Fix crash of Google storages when saving token file.
+- Make DAV discovery more RFC-conformant, see :ghpr:`585`.
 
 Version 0.15.0
 ==============

vdirsyncer/http.py

@@ -150,6 +150,8 @@ def request(method, url, session=None, latin1_fallback=True,
     if verify_fingerprint is not None:
         _install_fingerprint_adapter(session, verify_fingerprint)
 
+    session.hooks = dict(response=_fix_redirects)
+
     func = session.request
 
     logger.debug(u'{} {}'.format(method, url))
@@ -180,3 +182,21 @@ def request(method, url, session=None, latin1_fallback=True,
 
     r.raise_for_status()
     return r
+
+
+def _fix_redirects(r, *args, **kwargs):
+    '''
+    Requests discards of the body content when it is following a redirect that
+    is not a 307 or 308. We never want that to happen.
+
+    See:
+    https://github.com/kennethreitz/requests/issues/3915
+    https://github.com/pimutils/vdirsyncer/pull/585
+    https://github.com/pimutils/vdirsyncer/issues/586
+
+    FIXME: This solution isn't very nice. A new hook in requests would be
+    better.
+    '''
+    if r.is_redirect:
+        logger.debug('Rewriting status code from %s to 307', r.status_code)
+        r.status_code = 307

vdirsyncer/storage/dav.py

@@ -134,23 +134,14 @@ class Discover(object):
         _, collection = url.rstrip('/').rsplit('/', 1)
         return urlparse.unquote(collection)
 
-    def find_dav(self):
+    def find_principal(self):
         try:
-            response = self.session.request(
-                'GET', self._well_known_uri, allow_redirects=True,
-                headers=self.session.get_default_headers()
-            )
-            return response.url
+            return self._find_principal_impl('')
         except (HTTPError, exceptions.Error):
-            # The user might not have well-known URLs set up and instead points
-            # vdirsyncer directly to the DAV server.
-            dav_logger.debug('Server does not support well-known URIs.')
-            return ''
-
-    def find_principal(self, url=None):
-        if url is None:
-            url = self.find_dav()
+            dav_logger.debug('Trying out well-known URI')
+            return self._find_principal_impl(self._well_known_uri)
 
+    def _find_principal_impl(self, url):
         headers = self.session.get_default_headers()
         headers['Depth'] = '0'
         body = b"""
@@ -160,8 +151,10 @@ class Discover(object):
             </d:prop>
         </d:propfind>
         """
+
         response = self.session.request('PROPFIND', url, headers=headers,
                                         data=body)
+
         root = _parse_xml(response.content)
         rv = root.find('.//{DAV:}current-user-principal/{DAV:}href')
         if rv is None:
@@ -174,9 +167,8 @@ class Discover(object):
             return response.url
         return urlparse.urljoin(response.url, rv.text)
 
-    def find_home(self, url=None):
-        if url is None:
-            url = self.find_principal()
+    def find_home(self):
+        url = self.find_principal()
         headers = self.session.get_default_headers()
         headers['Depth'] = '0'
         response = self.session.request('PROPFIND', url,

vdirsyncer/storage/google.py

@@ -159,8 +159,13 @@ class GoogleContactsStorage(dav.CardDAVStorage):
     ''' + GOOGLE_PARAMS_DOCS
 
     class session_class(GoogleSession):
-        # Apparently Google wants us to submit a PROPFIND to the well-known
-        # URL, instead of looking for a redirect.
+        # Google CardDAV is completely bonkers. Collection discovery doesn't
+        # work properly, well-known URI takes us directly to single collection
+        # from where we can't discover principal or homeset URIs (the PROPFINDs
+        # 404).
+        #
+        # So we configure the well-known URI here again, such that discovery
+        # tries collection enumeration on it directly. That appears to work.
         url = 'https://www.googleapis.com/.well-known/carddav'
         scope = ['https://www.googleapis.com/auth/carddav']