Merge lp:~danilo/stega/proxy-support into lp:stega

[Данило Шеган]

Add support for handling X-Forwarded-For if hosted behind a semi-transparent
proxy (semi-transparent because it doesn't keep the REMOTE_ADDR but instead
uses X-Forwarded-For header).

[Sanja (sanjazivotic)]

review: Approve

=== modified file 'settings.py'
--- settings.py	2012-09-16 10:52:00 +0000
+++ settings.py	2012-09-16 11:02:19 +0000
@@ -16,6 +16,14 @@
 # Restrict number of short urls that can be created from a single ip address.
 URLS_PER_IP = 100
 
+# Whether installation is behind a proxy.
+# Warning: reads X-Forwarded-For to find out REMOTE_ADDR, so make sure you
+# do have a proxy server adding to X-Forwarded-For, since it can otherwise
+# be easily spoofed and will easily defeat the purpose of URLS_PER_IP
+# protection.
+TRANSPARENT_PROXY = True
+
+
 ADMINS = (
     ('Admin', 'root@localhost'),
 )
 
=== modified file 'url_shortener/tests.py'
--- url_shortener/tests.py	2012-09-16 10:52:00 +0000
+++ url_shortener/tests.py	2012-09-16 11:02:19 +0000
@@ -6,6 +6,7 @@
     TooManyUrlsError,
     Url,
 )
+from url_shortener.views import UrlCreationView
 import utils
 import settings
 
@@ -82,6 +83,9 @@
         self.assertEqual(200, response.status_code)
 
 
+class MockRequest(object):
+    META = {}
+
 class TestUrlCreationView(TestCase):
     def test_url_creation_view_success(self):
         response = self.client.post(
@@ -92,6 +96,32 @@
             response.content
         )
 
+    def test_get_ip_address_remote_addr(self):
+        # This reads back REMOTE_ADDR from the server environment.
+        request = MockRequest()
+        request.META = { 'REMOTE_ADDR': 'my-ip', }
+        self.assertEqual('my-ip', UrlCreationView.get_ip_address(request))
+
+    def test_get_ip_address_x_forwarded_to_no_proxy(self):
+        # This reads back REMOTE_ADDR from the server environment,
+        # and ignores X_FORWARDED_FOR when allow_proxy is False.
+        request = MockRequest()
+        request.META = { 'REMOTE_ADDR': 'my-ip',
+                         'X_FORWARDED_FOR': 'ip1, ip2'}
+        self.assertEqual(
+            'my-ip',
+            UrlCreationView.get_ip_address(request, allow_proxy=False))
+
+    def test_get_ip_address_x_forwarded_to_allow_proxy(self):
+        # This reads back REMOTE_ADDR from the server environment,
+        # and ignores X_FORWARDED_FOR when allow_proxy is False.
+        request = MockRequest()
+        request.META = { 'REMOTE_ADDR': 'my-ip',
+                         'X_FORWARDED_FOR': 'ip1, ip2'}
+        self.assertEqual(
+            'ip1',
+            UrlCreationView.get_ip_address(request, allow_proxy=True))
+
     def test_url_creation_view_no_param(self):
         response = self.client.post('/create/')
         self.assertEqual(400, response.status_code)
 
=== modified file 'url_shortener/views.py'
--- url_shortener/views.py	2012-09-15 09:11:25 +0000
+++ url_shortener/views.py	2012-09-16 11:02:19 +0000
@@ -39,11 +39,22 @@
 
 
 class UrlCreationView(View):
+    @staticmethod
+    def get_ip_address(request, allow_proxy=False):
+        if allow_proxy and 'X_FORWARDED_FOR' in request.META:
+            all_ips = request.META['X_FORWARDED_FOR'].split(',')
+            # Only the left-most one is accepted.
+            return all_ips[0]
+        else:
+            return request.META['REMOTE_ADDR']
+
     def post(self, request, **kwargs):
         try:
+            ip_address = self.get_ip_address(
+                request, settings.TRANSPARENT_PROXY)
             url = Url.get_or_create_url(
                 long_url=request.POST['long_url'],
-                ip_address=request.META['REMOTE_ADDR']
+                ip_address=ip_address,
             )
             host_name = request.META['HTTP_HOST']
             full_short_url = 'http://%s/%s' % (host_name, url.short_url)