Always wait for completion during SASL/GSSAPI authentication (dpkp#1248)

Author: dpkp

kafka/conn.py

@@ -6,8 +6,9 @@
 import logging
 from random import shuffle, uniform
 import socket
-import time
+import struct
 import sys
+import time
 
 from kafka.vendor import six
 
@@ -516,52 +517,40 @@ def _try_authenticate_gssapi(self, future):
         ctx_CanonName = ctx_Name.canonicalize(gssapi.MechType.kerberos)
         log.debug('%s: canonical Servicename: %s', self, ctx_CanonName)
         ctx_Context = gssapi.SecurityContext(name=ctx_CanonName, usage='initiate')
-        # Exchange tokens until authentication either succeeds or fails:
+        log.debug("%s: initiator name: %s", self, ctx_Context.initiator_name)
+
+        # Exchange tokens until authentication either succeeds or fails
         received_token = None
         try:
             while not ctx_Context.complete:
-                # calculate the output token
-                try:
-                    output_token = ctx_Context.step(received_token)
-                except GSSError as e:
-                    log.exception("%s: Error invalid token received from server",  self)
-                    error = Errors.ConnectionError("%s: %s" % (self, e))
+                # calculate an output token from kafka token (or None if first iteration)
+                output_token = ctx_Context.step(received_token)
 
-                if not output_token:
-                    if ctx_Context.complete:
-                        log.debug("%s: Security Context complete ", self)
-                    log.debug("%s: Successful GSSAPI handshake for %s", self, ctx_Context.initiator_name)
-                    break
+                # pass output token to kafka
                 try:
                     self._sock.setblocking(True)
-                    # Send output token
                     msg = output_token
                     size = Int32.encode(len(msg))
                     self._sock.sendall(size + msg)
-
                     # The server will send a token back. Processing of this token either
                     # establishes a security context, or it needs further token exchange.
                     # The gssapi will be able to identify the needed next step.
                     # The connection is closed on failure.
-                    response = self._sock.recv(2000)
+                    header = self._sock.recv(4)
+                    token_size = struct.unpack('>i', header)
+                    received_token = self._sock.recv(token_size)
                     self._sock.setblocking(False)
 
-                except (AssertionError, ConnectionError) as e:
+                except ConnectionError as e:
                     log.exception("%s: Error receiving reply from server",  self)
                     error = Errors.ConnectionError("%s: %s" % (self, e))
-                    future.failure(error)
                     self.close(error=error)
-
-                # pass the received token back to gssapi, strip the first 4 bytes
-                received_token = response[4:]
+                    return future.failure(error)
 
         except Exception as e:
-            log.exception("%s: GSSAPI handshake error",  self)
-            error = Errors.ConnectionError("%s: %s" % (self, e))
-            future.failure(error)
-            self.close(error=error)
+            return future.failure(e)
 
-        log.info('%s: Authenticated as %s', self, gssname)
+        log.info('%s: Authenticated as %s via GSSAPI', self, gssname)
         return future.success(True)
 
     def blacked_out(self):