Extract camo encoding to a library.

zerver/lib/bugdown/__init__.py

@@ -3,7 +3,6 @@ from __future__ import absolute_import
 # detailed documentation on our markdown syntax.
 from typing import Any
 
-import codecs
 import markdown
 import logging
 import traceback
@@ -20,10 +19,7 @@ import itertools
 from six.moves import urllib
 import xml.etree.cElementTree as etree
 
-import hashlib
-
 from collections import defaultdict
-import hmac
 
 import requests
 
@@ -33,6 +29,7 @@ from django.conf import settings
 from zerver.lib.avatar  import gravatar_hash
 from zerver.lib.bugdown import codehilite, fenced_code
 from zerver.lib.bugdown.fenced_code import FENCE_RE
+from zerver.lib.camo import get_camo_url
 from zerver.lib.timeout import timeout, TimeoutExpired
 from zerver.lib.cache import cache_with_key, cache_get_many, cache_set_many
 import zerver.lib.alert_words as alert_words
@@ -246,11 +243,7 @@ class InlineHttpsProcessor(markdown.treeprocessors.Treeprocessor):
             if not url.startswith("http://"):
                 # Don't rewrite images on our own site (e.g. emoji).
                 continue
-            encoded_url = url.encode("utf-8")
-            encoded_camo_key = settings.CAMO_KEY.encode("utf-8")
-            digest = hmac.new(encoded_camo_key, encoded_url, hashlib.sha1).hexdigest()
-            hex_encoded_url = codecs.encode(encoded_url, "hex")
-            img.set("src", "%s%s/%s" % (settings.CAMO_URI, digest, hex_encoded_url.decode("utf-8")))
+            img.set("src", get_camo_url(url))
 
 class InlineInterestingLinkProcessor(markdown.treeprocessors.Treeprocessor):
     TWITTER_MAX_IMAGE_HEIGHT = 400

zerver/lib/camo.py

@@ -0,0 +1,16 @@
+from django.conf import settings
+import codecs
+import hashlib
+import hmac
+
+# Encodes the provided URL using the same algorithm used by the camo
+# caching https image proxy
+def get_camo_url(url):
+    # Only encode the url if Camo is enabled
+    if settings.CAMO_URI == '':
+        return url
+    encoded_url = url.encode("utf-8")
+    encoded_camo_key = settings.CAMO_KEY.encode("utf-8")
+    digest = hmac.new(encoded_camo_key, encoded_url, hashlib.sha1).hexdigest()
+    hex_encoded_url = codecs.encode(encoded_url, "hex")
+    return "%s%s/%s" % (settings.CAMO_URI, digest, hex_encoded_url.decode("utf-8"))