Fix 500 for bogus Range request to 0-byte object.

The proxy was trying to pop a byterange off a Range header that didn't
contain syntactically-valid byteranges. This worked about as well as
you'd expect. Now we detect the bogus value and remove the header
entirely.

Change-Id: I24b92f900d33ec79880c7db2870378489d5a6810

swift/proxy/controllers/base.py

@@ -696,7 +696,12 @@ def pop_range(self):
         If we have no Range header, this is a no-op.
         """
         if 'Range' in self.backend_headers:
-            req_range = Range(self.backend_headers['Range'])
+            try:
+                req_range = Range(self.backend_headers['Range'])
+            except ValueError:
+                # there's a Range header, but it's garbage, so get rid of it
+                self.backend_headers.pop('Range')
+                return
             begin, end = req_range.ranges.pop(0)
             if len(req_range.ranges) > 0:
                 self.backend_headers['Range'] = str(req_range)

test/unit/proxy/test_server.py

@@ -1457,6 +1457,46 @@ def test_GET_ranges(self):
                          'bytes 4123-4523/5800')
         self.assertEqual(second_range_body, obj[4123:4524])
 
+    @unpatch_policies
+    def test_GET_bad_range_zero_byte(self):
+        prolis = _test_sockets[0]
+        prosrv = _test_servers[0]
+        sock = connect_tcp(('localhost', prolis.getsockname()[1]))
+        fd = sock.makefile()
+
+        path = '/v1/a/c/o.zerobyte'
+        fd.write('PUT %s HTTP/1.1\r\n'
+                 'Host: localhost\r\n'
+                 'Connection: close\r\n'
+                 'X-Storage-Token: t\r\n'
+                 'Content-Length: 0\r\n'
+                 'Content-Type: application/octet-stream\r\n'
+                 '\r\n' % (path,))
+        fd.flush()
+        headers = readuntil2crlfs(fd)
+        exp = 'HTTP/1.1 201'
+        self.assertEqual(headers[:len(exp)], exp)
+
+        # bad byte-range
+        req = Request.blank(
+            path,
+            environ={'REQUEST_METHOD': 'GET'},
+            headers={'Content-Type': 'application/octet-stream',
+                     'Range': 'bytes=spaghetti-carbonara'})
+        res = req.get_response(prosrv)
+        self.assertEqual(res.status_int, 200)
+        self.assertEqual(res.body, '')
+
+        # not a byte-range
+        req = Request.blank(
+            path,
+            environ={'REQUEST_METHOD': 'GET'},
+            headers={'Content-Type': 'application/octet-stream',
+                     'Range': 'Kotta'})
+        res = req.get_response(prosrv)
+        self.assertEqual(res.status_int, 200)
+        self.assertEqual(res.body, '')
+
     @unpatch_policies
     def test_GET_ranges_resuming(self):
         prolis = _test_sockets[0]