Add workaround for parsing a buggy older Hubzilla version nodeinfo

This has been fixed in later versions but there are quite a few
versions out with the bug so add a workaround to not crash on those.

federation/hostmeta/fetchers.py

@@ -13,10 +13,15 @@ def fetch_nodeinfo_document(host):
     doc = json.loads(doc)
 
     url, highest_version = '', 0.0
-    for link in doc.get('links'):
-        version = float(link.get('rel').split('/')[-1])
-        if version > highest_version and version <= HIGHEST_SUPPORTED_NODEINFO_VERSION:
-            url, highest_version = link.get('href'), version
+
+    if doc.get('0'):
+        # Buggy NodeInfo from certain old Hubzilla versions
+        url = doc.get('0', {}).get('href')
+    else:
+        for link in doc.get('links'):
+            version = float(link.get('rel').split('/')[-1])
+            if version > highest_version and version <= HIGHEST_SUPPORTED_NODEINFO_VERSION:
+                url, highest_version = link.get('href'), version
 
     if not url:
         return

federation/tests/fixtures/hostmeta.py

@@ -11,6 +11,11 @@ NODEINFO_20_DOC = '{"version":"2.0","software":{"name":"diaspora","version":"0.7
                   '22,"localComments":17671},"metadata":{"nodeName":"I Like Toast","xmppChat":false,"camo":{"' \
                   'markdown":false,"opengraph":false,"remotePods":false},"adminAccount":"podmin"}}'
 
+# Buggy NodeInfo well known found in certain older Hubzilla versions
+NODEINFO_WELL_KNOWN_BUGGY = '{"links":{"rel":"http:\/\/nodeinfo.diaspora.software\/ns\/schema\/1.0","href":"h' \
+                            'ttps:\/\/example.com\/nodeinfo\/1.0"},"0":{"rel":"http:\/\/nodeinfo.diaspo' \
+                            'ra.software\/ns\/schema\/2.0","href":"https:\/\/example.com\/nodeinfo\/2.0"}}'
+
 NODEINFO2_10_DOC = """
 {
   "version": "1.0",

federation/tests/hostmeta/test_fetchers.py

@@ -3,6 +3,7 @@ from unittest.mock import patch
 
 from federation.hostmeta.fetchers import (
     fetch_nodeinfo_document, fetch_nodeinfo2_document, fetch_statisticsjson_document)
+from federation.tests.fixtures.hostmeta import NODEINFO_WELL_KNOWN_BUGGY
 
 
 class TestFetchNodeInfoDocument:
@@ -23,6 +24,17 @@ class TestFetchNodeInfoDocument:
         assert kwargs['url'] == 'https://example.com/2.0'
         mock_parse.assert_called_once_with(json.loads(self.dummy_doc), 'example.com')
 
+    @patch("federation.hostmeta.fetchers.fetch_document",
+           return_value=(NODEINFO_WELL_KNOWN_BUGGY, 200, None), autospec=True)
+    @patch("federation.hostmeta.fetchers.parse_nodeinfo_document", autospec=True)
+    def test_makes_right_calls__buggy_nodeinfo_wellknown(self, mock_parse, mock_fetch):
+        fetch_nodeinfo_document('example.com')
+        args, kwargs = mock_fetch.call_args_list[0]
+        assert kwargs['host'] == 'example.com'
+        assert kwargs['path'] == '/.well-known/nodeinfo'
+        args, kwargs = mock_fetch.call_args_list[1]
+        assert kwargs['url'] == 'https://example.com/nodeinfo/2.0'
+
 
 class TestFetchNodeInfo2Document:
     @patch("federation.hostmeta.fetchers.fetch_document", return_value=('{"foo": "bar"}', 200, None), autospec=True)