--- /dev/null
+from django.conf import settings
+from django.http import QueryDict
+from django.utils.encoding import smart_str
+from django.utils.hashcompat import sha_constructor
+from django.utils.http import urlquote_plus, urlquote
+
+
+SEARCH_ARG_GET_KEY = 'q'
+URL_REDIRECT_GET_KEY = 'url'
+HASH_REDIRECT_GET_KEY = 's'
+
+
+def make_redirect_hash(search_arg, url):
+ return sha_constructor(smart_str(search_arg + url + settings.SECRET_KEY)).hexdigest()[::2]
+
+
+def check_redirect_hash(hash, search_arg, url):
+ return hash == make_redirect_hash(search_arg, url)
+
+
+def make_tracking_querydict(search_arg, url):
+ """
+ Returns a QueryDict instance containing the information necessary
+ for tracking clicks of this url.
+
+ NOTE: will this kind of initialization handle quoting correctly?
+ """
+ return QueryDict("%s=%s&%s=%s&%s=%s" % (
+ SEARCH_ARG_GET_KEY, urlquote_plus(search_arg),
+ URL_REDIRECT_GET_KEY, urlquote(url),
+ HASH_REDIRECT_GET_KEY, make_redirect_hash(search_arg, url))
+ )
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