Fixed #18314 -- Corrected request.build_absolute_uri() handling of paths starting with //

``HttpRequest.build_absolute_uri()`` now correctly handles paths starting with ``//``.
``WSGIRequest`` now doesn't remove all the leading slashes either,
because ``http://test/server`` and http://test//server`` aren't the same thing
(RFC2396).

Thanks to SmileyChris for the initial patch.

1 files changed, 19 insertions, 8 deletions

diff --git a/django/http/request.py b/django/http/request.py
index ded4744a87..84457c5300 100644
--- a/django/http/request.py
+++ b/django/http/request.py
@@ -15,7 +15,7 @@ from django.http.multipartparser import MultiPartParser, MultiPartParserError
 from django.utils import six
 from django.utils.datastructures import MultiValueDict, ImmutableList
 from django.utils.encoding import force_bytes, force_text, force_str, iri_to_uri
-from django.utils.six.moves.urllib.parse import parse_qsl, urlencode, quote, urljoin
+from django.utils.six.moves.urllib.parse import parse_qsl, urlencode, quote, urljoin, urlsplit
 
 
 RAISE_ERROR = object()
@@ -119,14 +119,25 @@ class HttpRequest(object):
     def build_absolute_uri(self, location=None):
         """
         Builds an absolute URI from the location and the variables available in
-        this request. If no location is specified, the absolute URI is built on
-        ``request.get_full_path()``.
+        this request. If no ``location`` is specified, the absolute URI is
+        built on ``request.get_full_path()``. Anyway, if the location is
+        absolute, it is simply converted to an RFC 3987 compliant URI and
+        returned and if location is relative or is scheme-relative (i.e.,
+        ``//example.com/``), it is urljoined to a base URL constructed from the
+        request variables.
         """
-        if not location:
-            location = self.get_full_path()
-        if not absolute_http_url_re.match(location):
-            current_uri = '%s://%s%s' % (self.scheme,
-                                         self.get_host(), self.path)
+        if location is None:
+            # Make it an absolute url (but schemeless and domainless) for the
+            # edge case that the path starts with '//'.
+            location = '//%s' % self.get_full_path()
+        bits = urlsplit(location)
+        if not (bits.scheme and bits.netloc):
+            current_uri = '{scheme}://{host}{path}'.format(scheme=self.scheme,
+                                                           host=self.get_host(),
+                                                           path=self.path)
+            # Join the constructed URL with the provided location, which will
+            # allow the provided ``location`` to apply query strings to the
+            # base path as well as override the host, if it begins with //
             location = urljoin(current_uri, location)
         return iri_to_uri(location)