multi_delete: limit the maximum number of objects

This introduces a config value to limit the maximum number of objects we can
delete with a multi delete request.  The default value is same as S3's one.

Change-Id: I77d404e43ba8532cbf81c680dcb82ec69b8f31cc

etc/proxy-server.conf-sample

@@ -33,6 +33,10 @@ use = egg:swift3#swift3
 # response.
 # max_bucket_listing = 1000
 #
+# Set the maximum number of objects we can delete with the Multi-Object Delete
+# operation.
+# max_multi_delete_objects = 1000
+#
 # Specify a host name of your Swift cluster.  This enables virtual-hosted style
 # requests.
 # storage_domain =

swift3/cfg.py

@@ -53,5 +53,6 @@ class Config(dict):
 CONF = Config({
     'location': 'US',
     'max_bucket_listing': 1000,
+    'max_multi_delete_objects': 1000,
     'storage_domain': '',
 })

swift3/controllers/multi_delete.py

@@ -18,6 +18,8 @@ from swift3.etree import Element, SubElement, fromstring, tostring, \
     XMLSyntaxError, DocumentInvalid
 from swift3.response import HTTPOk, S3NotImplemented, NoSuchKey, \
     ErrorResponse, MalformedXML
+from swift3.cfg import CONF
+from swift3.utils import LOGGER
 
 MAX_MULTI_DELETE_BODY_SIZE = 61365
 
@@ -33,10 +35,7 @@ class MultiObjectDeleteController(Controller):
         Handles Delete Multiple Objects.
         """
         def object_key_iter(xml):
-            try:
-                elem = fromstring(xml, 'Delete')
-            except (XMLSyntaxError, DocumentInvalid):
-                raise MalformedXML()
+            elem = fromstring(xml, 'Delete')
 
             for obj in elem.iterchildren('Object'):
                 key = obj.find('./Key').text
@@ -48,8 +47,20 @@ class MultiObjectDeleteController(Controller):
 
         elem = Element('DeleteResult')
 
-        xml = req.xml(MAX_MULTI_DELETE_BODY_SIZE, check_md5=True)
-        for key, version in object_key_iter(xml):
+        try:
+            xml = req.xml(MAX_MULTI_DELETE_BODY_SIZE, check_md5=True)
+            delete_list = list(object_key_iter(xml))
+            if len(delete_list) > CONF.max_multi_delete_objects:
+                raise MalformedXML()
+        except (XMLSyntaxError, DocumentInvalid):
+            raise MalformedXML()
+        except ErrorResponse:
+            raise
+        except Exception as e:
+            LOGGER.error(e)
+            raise
+
+        for key, version in delete_list:
             if version is not None:
                 # TODO: delete the specific version of the object
                 raise S3NotImplemented()

swift3/test/unit/test_multi_delete.py

@@ -22,6 +22,7 @@ from swift.common.swob import Request
 
 from swift3.test.unit import Swift3TestCase
 from swift3.etree import tostring, Element, SubElement
+from swift3.cfg import CONF
 
 
 class TestSwift3MultiDelete(Swift3TestCase):
@@ -97,5 +98,21 @@ class TestSwift3MultiDelete(Swift3TestCase):
         status, headers, body = self.call_swift3(req)
         self.assertEquals(self._get_error_code(body), 'InvalidRequest')
 
+    def test_object_multi_DELETE_too_many_keys(self):
+        elem = Element('Delete')
+        for i in range(CONF.max_multi_delete_objects + 1):
+            obj = SubElement(elem, 'Object')
+            SubElement(obj, 'Key').text = str(i)
+        body = tostring(elem, use_s3ns=False)
+        content_md5 = md5(body).digest().encode('base64').strip()
+
+        req = Request.blank('/bucket?delete',
+                            environ={'REQUEST_METHOD': 'POST'},
+                            headers={'Authorization': 'AWS test:tester:hmac',
+                                     'Content-MD5': content_md5},
+                            body=body)
+        status, headers, body = self.call_swift3(req)
+        self.assertEquals(self._get_error_code(body), 'MalformedXML')
+
 if __name__ == '__main__':
     unittest.main()