Release #302 and #313.

web_monitoring/diffing_server.py

@@ -307,16 +307,37 @@ def _extract_encoding(headers, content):
         prolog_match = XML_PROLOG_PATTERN.search(content, endpos=2048)
         if prolog_match:
             encoding = prolog_match.group(1).decode('ascii', errors='ignore')
+    # Handle common mistakes and errors in encoding names
+    if encoding == 'iso-8559-1':
+        encoding = 'iso-8859-1'
+    # Windows-1252 is so commonly mislabeled, WHATWG recommends assuming it's a
+    # mistake: https://encoding.spec.whatwg.org/#names-and-labels
+    if encoding == 'iso-8859-1' and 'html' in content_type:
+        encoding = 'windows-1252'
     return encoding
 
 
 def _decode_body(response, name, raise_if_binary=True):
     encoding = _extract_encoding(response.headers, response.body) or 'UTF-8'
-    text = response.body.decode(encoding, errors='replace')
+    try:
+        text = response.body.decode(encoding, errors='replace')
+    except LookupError:
+        # If the encoding we found isn't known, fall back to ascii
+        text = response.body.decode('ascii', errors='replace')
+
+    text_length = len(text)
+    if text_length == 0:
+        return text
+
+    # Replace null terminators; some differs (especially those written in C)
+    # don't handle them well in the middle of a string.
+    text = text.replace('\u0000', '\ufffd')
+
     # If a significantly large portion of the document was totally undecodable,
     # it's likely this wasn't text at all, but binary data.
-    if raise_if_binary and text.count('\ufffd') / len(text) > 0.25:
+    if raise_if_binary and text.count('\ufffd') / text_length > 0.25:
         raise UndecodableContentError(f'The response body of `{name}` could not be decoded as {encoding}.')
+
     return text
 
 

web_monitoring/html_diff_render.py

@@ -299,10 +299,13 @@ def html_diff_render(a_text, b_text, a_headers=None, b_headers=None,
 
         color_palette = get_color_palette()
         change_styles.string = f'''
-            ins, ins > * {{text-decoration: none; background-color:
-                {color_palette['differ_insertion']};}}
-            del, del > * {{text-decoration: none; background-color:
-                {color_palette['differ_deletion']};}}'''
+            ins.wm-diff, ins.wm-diff > * {{background-color:
+                {color_palette['differ_insertion']} !important;
+                all: unset;}}
+            del.wm-diff, del.wm-diff > * {{background-color:
+                {color_palette['differ_deletion']} !important;
+                all: unset;}}
+            script {{display: none !important;}}'''
         soup.head.append(change_styles)
 
         soup.body.replace_with(diff_body)
@@ -351,9 +354,9 @@ def _html_for_dmp_operation(operation):
     "Convert a diff-match-patch operation to an HTML string."
     html_value = html.escape(operation[1])
     if operation[0] == -1:
-        return f'<del>{html_value}</del>'
+        return f'<del class="wm-diff">{html_value}</del>'
     elif operation[0] == 1:
-        return f'<ins>{html_value}</ins>'
+        return f'<ins class="wm-diff">{html_value}</ins>'
     else:
         return html_value
 
@@ -1118,7 +1121,7 @@ def merge_changes(change_chunks, doc, tag_type='ins'):
 
                             doc.append(f'</{tag_type}>')
                             doc.append(chunk)
-                            doc.append(f'<{tag_type}>')
+                            doc.append(f'<{tag_type} class="wm-diff">')
 
                             # other side of the malformed document case from above
                             current_content.reverse()
@@ -1144,7 +1147,7 @@ def merge_changes(change_chunks, doc, tag_type='ins'):
                     inline_tag_name = name
 
         if depth == 0:
-            doc.append(f'<{tag_type}>')
+            doc.append(f'<{tag_type} class="wm-diff">')
             depth += 1
             current_content = []
 
@@ -1389,7 +1392,7 @@ def merge_change_groups(change_chunks, doc, tag_type=None):
                             # doc.append(group)
                             # <end> not sure if we should break the group
                             if tag_type:
-                                group.append(f'<{tag_type}>')
+                                group.append(f'<{tag_type} class="wm-diff">')
 
                             # other side of the malformed document case from above
                             current_content.reverse()
@@ -1420,7 +1423,7 @@ def merge_change_groups(change_chunks, doc, tag_type=None):
             group = []
             doc.append(group)
             if tag_type:
-                group.append(f'<{tag_type}>')
+                group.append(f'<{tag_type} class="wm-diff">')
             depth += 1
             current_content = []
 
@@ -1582,7 +1585,7 @@ def tag_info(token):
             # if we have a hanging delete buffer (with content, not just HTML
             # DOM structure), clean it up and insert it before moving on.
             # FIXME: this should not look explicitly for `<del>`
-            if '<del>' in delete_buffer:
+            if '<del class="wm-diff">' in delete_buffer:
                 for tag in delete_tag_stack:
                     delete_buffer.append(f'</{tag[0]}>')
                 document.extend(delete_buffer)
@@ -1627,7 +1630,7 @@ def tag_info(token):
     # Add any hanging buffer of deletes that never got completed, but only if
     # it has salient changes in it.
     # FIXME: this should not look explicitly for `<del>`
-    if '<del>' in delete_buffer:
+    if '<del class="wm-diff">' in delete_buffer:
         for tag in delete_tag_stack:
             delete_buffer.append(f'</{tag[0]}>')
         document.extend(delete_buffer)

web_monitoring/links_diff.py

@@ -125,10 +125,11 @@ def links_diff_html(a_text, b_text, a_headers=None, b_headers=None,
             background-color: {color_palette['differ_insertion']};}}
         [wm-deleted] > td  {{
             background-color: {color_palette['differ_deletion']};}}
-        ins {{ text-decoration: none;
-            background-color: {color_palette['differ_insertion']};}}
-        del {{ text-decoration: none;
-            background-color: {color_palette['differ_deletion']};}}"""
+        ins.wm-diff {{ background-color: {color_palette['differ_insertion']}
+        !important; all: unset;}}
+        del.wm-diff {{ background-color: {color_palette['differ_deletion']}
+        !important; all: unset;}}
+        script {{display: none !important;}}"""
 
     soup.head.append(change_styles)
     soup.title.string = get_title(diff['b_parsed'])

web_monitoring/tests/fixtures/unknown_encoding.html

@@ -0,0 +1,25 @@
+<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
+<html>
+<head>
+<meta http-equiv="refresh" content="60; url=http://radar2pub.bldr.ncep.noaa.gov">
+<meta http-equiv="Content-Type" content="text/html; charset=who-knows-what-i-am">
+<meta name="Author" content="David S Alden (GMSI)">
+<title>NWS Level II Radar Receive Status</title>
+<link rel="stylesheet" type="text/css" href="mon.css">
+</head>
+<body>
+<font face="arial,helvetica" size=+2><b>NWS Level II Radar Receive Status as of Tue Jan 17 14:14:06 UTC 2017</b></font><br>
+<br>Key: Green=Up (Lvl2&lt;5 min); Yellow=Warning (5&lt;=Lvl2&lt;30 min); Orange=Down (Lvl2&amp;Lvl3&gt;10 min); Red=Down (Lvl2&gt;=30 min)<br>
+SiteID: Black=Ok (-1&lt;=Latency&lt;=60 sec); White=Anomaly (-1&gt;Latency&gt;60 sec)<br>
+SiteCodes: 01=Legacy Msg1; 02=Legacy Msg31; 03=Super-Res; 04=Recombined; 05=DP w/o SuperRes; 06=DP w Super Res; 07=DP Recombined<br><br>
+<p><b><font face="arial,helvetica">Eastern Region Radar Sites - Last receipt of data</font></b>
+<table BORDER=0 CELLSPACING=4><tr>
+<td ALIGN=CENTER BGCOLOR="#33FF33" class=black id=blacklink TITLE="Wakefield VA" VALIGN=middle><b><A HREF="site/kakq.html" TARGET="_blank">KAKQ</a></b><span class=black>06<br>14:13:02</span></td>
+<td ALIGN=CENTER BGCOLOR="#33FF33" class=black id=blacklink TITLE="Binghamton NY" VALIGN=middle><b><A HREF="site/kbgm.html" TARGET="_blank">KBGM</a></b><span class=black>06<br>14:13:03</span></td>
+<td ALIGN=CENTER BGCOLOR="#FF0000" class=black id=blacklink TITLE="Boston MA" VALIGN=middle><b><A HREF="site/kbox.html" TARGET="_blank">KBOX</a></b><span class=black>06<br>13:12:47</span></td>
+<td ALIGN=CENTER BGCOLOR="#33FF33" class=black id=blacklink TITLE="Buffalo NY" VALIGN=middle><b><A HREF="site/kbuf.html" TARGET="_blank">KBUF</a></b><span class=black>06<br>14:13:04</span></td>
+</tr></table>
+<font face="Arial,Helvetica">44 sites up (97.8%) of 45 radar sites monitored</font>
+<p><font face="arial,helvetica"> 151 sites up (96%) of 158 total radar sites monitored</font>
+</body>
+</html>

web_monitoring/tests/test_diffing_server_exc_handling.py

@@ -188,6 +188,10 @@ def test_cors_origin_header(self):
                                        'Origin': 'http://two.com'})
         assert response.headers.get('Access-Control-Allow-Origin') == 'http://two.com'
 
+    def test_decode_empty_bodies(self):
+        response = mock_tornado_request('empty.txt')
+        df._decode_body(response, 'a')
+
     def test_poorly_encoded_content(self):
         response = mock_tornado_request('poorly_encoded_utf8.txt')
         df._decode_body(response, 'a')
@@ -204,6 +208,16 @@ def test_fetch_undecodable_content(self):
         self.json_check(response)
         assert response.code == 422
 
+    def test_treats_unknown_encoding_as_ascii(self):
+        response = mock_tornado_request('unknown_encoding.html')
+        df._decode_body(response, 'a')
+
+    def test_diff_content_with_null_bytes(self):
+        response = self.fetch('/html_source_dmp?format=json&'
+                              f'a=file://{fixture_path("has_null_byte.txt")}&'
+                              f'b=file://{fixture_path("has_null_byte.txt")}')
+        assert response.code == 200
+
 
 def mock_diffing_method(c_body):
     return