Fix UnicodeDecodeError when decode API input

Convert UnicodeDecodeError to HTTPBadRequest in
FaultWrapper.

Change-Id: I826f05084b0a0ef170ef293d382868409b96ed3d
Closes-Bug: #1746202

manila/api/middleware/fault.py

@@ -20,6 +20,7 @@ import webob.dec
 import webob.exc
 
 from manila.api.openstack import wsgi
+from manila.i18n import _
 from manila import utils
 from manila.wsgi import common as base_wsgi
 
@@ -40,6 +41,11 @@ class FaultWrapper(base_wsgi.Middleware):
             status, webob.exc.HTTPInternalServerError)()
 
     def _error(self, inner, req):
+        if isinstance(inner, UnicodeDecodeError):
+            msg = _("Error decoding your request. Either the URL or the "
+                    "request body contained characters that could not be "
+                    "decoded by Manila.")
+            return wsgi.Fault(webob.exc.HTTPBadRequest(explanation=msg))
         LOG.exception("Caught error: %s", inner)
 
         safe = getattr(inner, 'safe', False)

manila/tests/api/middleware/test_faults.py

@@ -184,3 +184,12 @@ class ExceptionTest(test.TestCase):
         api = self._wsgi_app(fail)
         resp = webob.Request.blank('/').get_response(api)
         self.assertEqual(500, resp.status_int)
+
+    def test_validate_request_unicode_decode_fault(self):
+        @webob.dec.wsgify
+        def unicode_error(req):
+            raise UnicodeDecodeError("ascii", "test".encode(), 0, 1, "bad")
+
+        api = self._wsgi_app(unicode_error)
+        resp = webob.Request.blank('/test?foo=%88').get_response(api)
+        self.assertEqual(400, resp.status_int)

releasenotes/notes/bug-1746202-fix-unicodeDecodeError-when-decode-API-input-4e4502fb50b69502.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - This patch converts UnicodeDecodeError exception into BadRequest, plus
+    an explicit error message. Fix invalid query parameter could lead to
+    HTTP 500.