From 63f3079c0a788e057963278036a1caa5d642e0cc Mon Sep 17 00:00:00 2001
From: Benjamin Dauvergne <bdauvergne@entrouvert.com>
Date: Fri, 12 Apr 2019 19:07:26 +0200
Subject: [PATCH 1/3] utils: add a same_origin(url1, url2) helper (#32239)

---
 combo/utils/urls.py | 47 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/combo/utils/urls.py b/combo/utils/urls.py
index 57e67be..7d0c439 100644
--- a/combo/utils/urls.py
+++ b/combo/utils/urls.py
@@ -20,6 +20,7 @@ from django.conf import settings
 from django.utils.encoding import force_text
 from django.template import Context, Template, TemplateSyntaxError, VariableDoesNotExist
 from django.utils.http import quote
+from django.utils.six.moves.urllib import parse as urlparse
 
 
 class TemplateError(Exception):
@@ -62,3 +63,49 @@ def get_templated_url(url, context=None):
             raise TemplateError('unknown variable %s', varname)
         return force_text(template_vars[varname])
     return re.sub(r'(\[.+?\])', repl, url)
+
+PROTOCOLS_TO_PORT = {
+    'http': '80',
+    'https': '443',
+}
+
+
+def same_domain(domain1, domain2):
+    if domain1 == domain2:
+        return True
+
+    if not domain1 or not domain2:
+        return False
+
+    if domain2.startswith('.'):
+        # p1 is a sub-domain or the base domain
+        if domain1.endswith(domain2) or domain1 == domain2[1:]:
+            return True
+    return False
+
+
+def same_origin(url1, url2):
+    '''Checks if both URL use the same domain. It understands domain patterns on url2, i.e. .example.com
+    matches www.example.com.
+
+    If not scheme is given in url2, scheme compare is skipped.
+    If not scheme and not port are given, port compare is skipped.
+    The last two rules allow authorizing complete domains easily.
+    '''
+    p1, p2 = urlparse.urlparse(url1), urlparse.urlparse(url2)
+
+    if p2.scheme and p1.scheme != p2.scheme:
+        return False
+
+    if not same_domain(p1.hostname, p2.hostname):
+        return False
+
+    try:
+        if (p2.port or (p1.port and p2.scheme)) and (
+                (p1.port or PROTOCOLS_TO_PORT[p1.scheme])
+                != (p2.port or PROTOCOLS_TO_PORT[p2.scheme])):
+            return False
+    except (ValueError, KeyError):
+        return False
+
+    return True
-- 
2.20.1