Fix error handling in proxy/controllers/base.py.

There are a few issues going on in the
controllers/base.py:_get_response_parts_iter(). One is that the
"raise" statement that attempts to re-raise the GeneratorExit, may
re-raise ValueError if that was the last exception caught.

Secondly, the range may not actually be set in the backend_headers
(need to investigate further, as that could actually be faulty tests,
since learn_size_from_content_range should always set it). The patch
changes the Range construction to throw a ValueError if None is passed
in that case.

Lastly, the range may be only half-defined, e.g. bytes=0-. In that
case, the check of how many bytes are expected vs how many bytes have
been sent does not make sense.

Change-Id: Ida5adf3d33c736240b2c4bae5510b5289f03dee2

swift/common/swob.py

@@ -467,6 +467,8 @@ class Range(object):
     :param headerval: value of the header as a str
     """
     def __init__(self, headerval):
+        if not headerval:
+            raise ValueError('Invalid Range header: %r' % headerval)
         headerval = headerval.replace(' ', '')
         if not headerval.lower().startswith('bytes='):
             raise ValueError('Invalid Range header: %s' % headerval)

swift/proxy/controllers/base.py

@@ -1061,6 +1061,7 @@ class ResumingGetter(object):
                 self.app.client_timeout)
             self.app.logger.increment('client_timeouts')
         except GeneratorExit:
+            exc_type, exc_value, exc_traceback = exc_info()
             warn = True
             try:
                 req_range = Range(self.backend_headers['Range'])
@@ -1068,11 +1069,12 @@ class ResumingGetter(object):
                 req_range = None
             if req_range and len(req_range.ranges) == 1:
                 begin, end = req_range.ranges[0]
-                if end - begin + 1 == self.bytes_used_from_backend:
-                    warn = False
+                if end is not None and begin is not None:
+                    if end - begin + 1 == self.bytes_used_from_backend:
+                        warn = False
             if not req.environ.get('swift.non_client_disconnect') and warn:
                 self.app.logger.warning(_('Client disconnected on read'))
-            raise
+            six.reraise(exc_type, exc_value, exc_traceback)
         except Exception:
             self.app.logger.exception(_('Trying to send to client'))
             raise

test/unit/common/test_swob.py

@@ -249,6 +249,7 @@ class TestRange(unittest.TestCase):
         6. any combination of the above
         """
 
+        _assert_invalid_range(None)
         _assert_invalid_range('nonbytes=foobar,10-2')
         _assert_invalid_range('bytes=5-3')
         _assert_invalid_range('bytes=-')