support image proxying using atmos/camo

woodwind/templates/_entry.jinja2

@@ -2,7 +2,7 @@
   <article class="reply-context">
     <header>
       {% if context.author_photo %}
-        <img src="{{context.author_photo}}"/>
+        <img src="{{context.author_photo|proxy_image}}"/>
       {% endif %}
       {% if context.author_name %}
         {{ context.author_name }} -
@@ -14,7 +14,7 @@
     {% endif %}
     {% if context.content %}
       <div class="content">
-        {{ context.content_cleaned | add_preview }}
+        {{ context.content_cleaned | proxy_all | add_preview }}
       </div>
     {% endif %}
     <footer>
@@ -30,7 +30,7 @@
 <article>
   <header>
     {% if entry.author_photo %}
-      <img src="{{entry.author_photo}}"/>
+      <img src="{{entry.author_photo|proxy_image}}"/>
     {% endif %}
     {% if entry.author_name %}
       {{ entry.author_name }} -
@@ -47,7 +47,7 @@
   {% endif %}
   {% if entry.content %}
     <div class="content">
-      {{ entry.content_cleaned | add_preview }}
+      {{ entry.content_cleaned | proxy_all | add_preview }}
     </div>
   {% endif %}
 

woodwind/templates/feed.jinja2

@@ -31,7 +31,6 @@
 {% endblock header %}
 
 {% block body %}
-
   <div class="button-link">
     <a id="unfold-link" href="#">n New Entries</a>
   </div>

woodwind/views.py

@@ -7,6 +7,8 @@ import bs4
 import datetime
 import feedparser
 import flask
+import hashlib
+import hmac
 import mf2py
 import mf2util
 import requests
@@ -15,6 +17,9 @@ import urllib
 import cgi
 import sqlalchemy
 
+IMAGE_TAG_RE = re.compile(r'<img([^>]*) src="(https?://[^">]+)"')
+
+
 views = flask.Blueprint('views', __name__)
 
 
@@ -558,7 +563,7 @@ def add_preview(content):
     """If a post ends with the URL of a known media source (youtube,
     instagram, etc.), add the content inline.
     """
-    if any('<' + tag in content for tag in (
+    if not content or any('<' + tag in content for tag in (
             'img', 'iframe', 'embed', 'audio', 'video')):
         # don't add  a preview to a post that already has one
         return content
@@ -600,6 +605,28 @@ def add_preview(content):
     return content
 
     
+@views.app_template_filter()
+def proxy_image(url):
+    camo_url = flask.current_app.config.get('CAMO_URL')
+    camo_key = flask.current_app.config.get('CAMO_KEY')
+    if not camo_url or not camo_key:
+        return url
+    digest = hmac.new(camo_key.encode(), url.encode(), hashlib.sha1).hexdigest()
+    return (urllib.parse.urljoin(camo_url, digest)
+            + '?url=' + urllib.parse.quote_plus(url))
+    
+        
+@views.app_template_filter()
+def proxy_all(content):
+    def repl(m):
+        attrs = m.group(1)
+        url = m.group(2)
+        url = url.replace('&amp;', '&')
+        return '<img{} src="{}"'.format(attrs, proxy_image(url))
+    if content:
+        return IMAGE_TAG_RE.sub(repl, content)
+
+
 @views.app_template_global()
 def url_for_other_page(page):
     """http://flask.pocoo.org/snippets/44/#URL+Generation+Helper