Add middleware to support ssl termination proxies

This change defines SSLMiddleware middleware which enables OpenStack
services behind SSL termination proxies to return urls with original
protocol scheme.

SSLMiddleware is based on heat SSLMiddleware class.

Change-Id: I72f8da160ced6ac80fdac743c00ea3f7ffb1f57c
Closes-Bug: #1444490

4 files changed, 104 insertions, 2 deletions

diff --git a/oslo_middleware/__init__.py b/oslo_middleware/__init__.py
index ae0965b..b2ea8c0 100644
--- a/oslo_middleware/__init__.py
+++ b/oslo_middleware/__init__.py
@@ -16,7 +16,8 @@ __all__ = ['CatchErrors',
            'Debug',
            'Healthcheck',
            'RequestId',
-           'RequestBodySizeLimiter']
+           'RequestBodySizeLimiter',
+           'SSLMiddleware']
 
 from oslo_middleware.catch_errors import CatchErrors
 from oslo_middleware.correlation_id import CorrelationId
@@ -25,3 +26,4 @@ from oslo_middleware.debug import Debug
 from oslo_middleware.healthcheck import Healthcheck
 from oslo_middleware.request_id import RequestId
 from oslo_middleware.sizelimit import RequestBodySizeLimiter
+from oslo_middleware.ssl import SSLMiddleware
diff --git a/oslo_middleware/opts.py b/oslo_middleware/opts.py
index d322291..c19f272 100644
--- a/oslo_middleware/opts.py
+++ b/oslo_middleware/opts.py
@@ -22,6 +22,7 @@ import copy
 
 from oslo_middleware import cors
 from oslo_middleware import sizelimit
+from oslo_middleware import ssl
 
 
 def list_opts():
@@ -44,7 +45,7 @@ def list_opts():
     :returns: a list of (group_name, opts) tuples
     """
     return [
-        ('oslo_middleware', copy.deepcopy(sizelimit._opts)),
+        ('oslo_middleware', copy.deepcopy(sizelimit._opts + ssl.OPTS)),
         ('cors', copy.deepcopy(cors.CORS_OPTS)),
         ('cors.subdomain', copy.deepcopy(cors.CORS_OPTS))
     ]
diff --git a/oslo_middleware/ssl.py b/oslo_middleware/ssl.py
new file mode 100644
index 0000000..97293f3
--- /dev/null
+++ b/oslo_middleware/ssl.py
@@ -0,0 +1,43 @@
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied. See the License for the specific language governing permissions and
+# limitations under the License.
+
+from oslo.config import cfg
+from oslo_middleware import base
+
+
+OPTS = [
+    cfg.StrOpt('secure_proxy_ssl_header',
+               default='X-Forwarded-Proto',
+               help="The HTTP Header that will be used to determine what "
+                    "the original request protocol scheme was, even if it was "
+                    "hidden by an SSL termination proxy.")
+]
+cfg.CONF.register_opts(OPTS, group='oslo_middleware')
+
+
+class SSLMiddleware(base.Middleware):
+    """SSL termination proxies middleware.
+
+    This middleware overloads wsgi.url_scheme with the one provided in
+    secure_proxy_ssl_header header. This is useful when behind a SSL
+    termination proxy.
+    """
+
+    def __init__(self, application):
+        super(SSLMiddleware, self).__init__(application)
+        self.header_name = 'HTTP_{0}'.format(
+            cfg.CONF.oslo_middleware.secure_proxy_ssl_header.upper()
+            .replace('-', '_'))
+
+    def process_request(self, req):
+        req.environ['wsgi.url_scheme'] = req.environ.get(
+            self.header_name, req.environ['wsgi.url_scheme'])
diff --git a/oslo_middleware/tests/test_ssl.py b/oslo_middleware/tests/test_ssl.py
new file mode 100644
index 0000000..7314260
--- /dev/null
+++ b/oslo_middleware/tests/test_ssl.py
@@ -0,0 +1,56 @@
+# Copyright (c) 2015 Thales Services SAS
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from oslo_config import cfg
+from oslo_config import fixture as config
+from oslotest import base
+import webob
+
+from oslo_middleware import ssl
+
+
+class SSLMiddlewareTest(base.BaseTestCase):
+
+    def setUp(self):
+        super(SSLMiddlewareTest, self).setUp()
+        self.useFixture(config.Config())
+
+    def _test_scheme(self, expected, headers):
+        middleware = ssl.SSLMiddleware(None)
+        request = webob.Request.blank('http://example.com/', headers=headers)
+
+        # Ensure ssl middleware does not stop pipeline execution
+        self.assertIsNone(middleware.process_request(request))
+
+        self.assertEqual(expected, request.scheme)
+
+    def test_without_forwarded_protocol(self):
+        self._test_scheme('http', {})
+
+    def test_with_forwarded_protocol(self):
+        headers = {'X-Forwarded-Proto': 'https'}
+        self._test_scheme('https', headers)
+
+    def test_with_custom_header(self):
+        cfg.CONF.set_override('secure_proxy_ssl_header', 'X-My-Header',
+                              group='oslo_middleware')
+        headers = {'X-Forwarded-Proto': 'https'}
+        self._test_scheme('http', headers)
+
+    def test_with_custom_header_and_forwarded_protocol(self):
+        cfg.CONF.set_override('secure_proxy_ssl_header', 'X-My-Header',
+                              group='oslo_middleware')
+        headers = {'X-My-Header': 'https'}
+        self._test_scheme('https', headers)