Add maximum message size checks. Closes #151.

ansible_mitogen/process.py

@@ -134,7 +134,7 @@ class MuxProcess(object):
         """
         Construct a Router, Broker, and mitogen.unix listener
         """
-        self.router = mitogen.master.Router()
+        self.router = mitogen.master.Router(max_message_size=4096*1048576)
         self.router.responder.whitelist_prefix('ansible')
         self.router.responder.whitelist_prefix('ansible_mitogen')
         mitogen.core.listen(self.router.broker, 'shutdown', self.on_broker_shutdown)

mitogen/core.py

@@ -812,6 +812,12 @@ class Stream(BasicStream):
             self._input_buf[0][:self.HEADER_LEN],
         )
 
+        if msg_len > self._router.max_message_size:
+            LOG.error('Maximum message size exceeded (got %d, max %d)',
+                      msg_len, self._router.max_message_size)
+            self.on_disconnect(broker)
+            return False
+
         total_len = msg_len + self.HEADER_LEN
         if self._input_buf_len < total_len:
             _vv and IOLOG.debug(
@@ -1191,6 +1197,7 @@ class IoLogger(BasicStream):
 
 class Router(object):
     context_class = Context
+    max_message_size = 128 * 1048576
 
     def __init__(self, broker):
         self.broker = broker
@@ -1274,6 +1281,11 @@ class Router(object):
 
     def _async_route(self, msg, stream=None):
         _vv and IOLOG.debug('%r._async_route(%r, %r)', self, msg, stream)
+        if len(msg.data) > self.max_message_size:
+            LOG.error('message too large (max %d bytes): %r',
+                      self.max_message_size, msg)
+            return
+
         # Perform source verification.
         if stream is not None:
             expected_stream = self._stream_by_id.get(msg.auth_id,
@@ -1438,7 +1450,9 @@ class ExternalContext(object):
         _v and LOG.debug('%r: parent stream is gone, dying.', self)
         self.broker.shutdown()
 
-    def _setup_master(self, profiling, parent_id, context_id, in_fd, out_fd):
+    def _setup_master(self, max_message_size, profiling, parent_id,
+                      context_id, in_fd, out_fd):
+        Router.max_message_size = max_message_size
         self.profiling = profiling
         if profiling:
             enable_profiling()
@@ -1571,9 +1585,11 @@ class ExternalContext(object):
         self.dispatch_stopped = True
 
     def main(self, parent_ids, context_id, debug, profiling, log_level,
-             in_fd=100, out_fd=1, core_src_fd=101, setup_stdio=True,
-             setup_package=True, importer=None, whitelist=(), blacklist=()):
-        self._setup_master(profiling, parent_ids[0], context_id, in_fd, out_fd)
+             max_message_size, in_fd=100, out_fd=1, core_src_fd=101,
+             setup_stdio=True, setup_package=True, importer=None,
+             whitelist=(), blacklist=()):
+        self._setup_master(max_message_size, profiling, parent_ids[0],
+                           context_id, in_fd, out_fd)
         try:
             try:
                 self._setup_logging(debug, log_level)

mitogen/fakessh.py

@@ -343,14 +343,15 @@ def run(dest, router, args, deadline=None, econtext=None):
             fp.write(inspect.getsource(mitogen.core))
             fp.write('\n')
             fp.write('ExternalContext().main(**%r)\n' % ({
-                'parent_ids': parent_ids,
                 'context_id': context_id,
+                'core_src_fd': None,
                 'debug': getattr(router, 'debug', False),
-                'profiling': getattr(router, 'profiling', False),
-                'log_level': mitogen.parent.get_log_level(),
                 'in_fd': sock2.fileno(),
+                'log_level': mitogen.parent.get_log_level(),
+                'max_message_size': router.max_message_size,
                 'out_fd': sock2.fileno(),
-                'core_src_fd': None,
+                'parent_ids': parent_ids,
+                'profiling': getattr(router, 'profiling', False),
                 'setup_stdio': False,
             },))
         finally:

mitogen/fork.py

@@ -85,9 +85,11 @@ class Stream(mitogen.parent.Stream):
     #: User-supplied function for cleaning up child process state.
     on_fork = None
 
-    def construct(self, old_router, on_fork=None, debug=False, profiling=False):
+    def construct(self, old_router, max_message_size, on_fork=None,
+                  debug=False, profiling=False):
         # fork method only supports a tiny subset of options.
-        super(Stream, self).construct(debug=debug, profiling=profiling)
+        super(Stream, self).construct(max_message_size=max_message_size,
+                                      debug=debug, profiling=profiling)
         self.on_fork = on_fork
 
         responder = getattr(old_router, 'responder', None)

mitogen/master.py

@@ -646,9 +646,11 @@ class Router(mitogen.parent.Router):
     debug = False
     profiling = False
 
-    def __init__(self, broker=None):
+    def __init__(self, broker=None, max_message_size=None):
         if broker is None:
             broker = self.broker_class()
+        if max_message_size:
+            self.max_message_size = max_message_size
         super(Router, self).__init__(broker)
         self.upgrade()
 

mitogen/parent.py

@@ -337,6 +337,10 @@ class Stream(mitogen.core.Stream):
     #: Set to the child's PID by connect().
     pid = None
 
+    #: Passed via Router wrapper methods, must eventually be passed to
+    #: ExternalContext.main().
+    max_message_size = None
+
     def __init__(self, *args, **kwargs):
         super(Stream, self).__init__(*args, **kwargs)
         self.sent_modules = set(['mitogen', 'mitogen.core'])
@@ -344,12 +348,13 @@ class Stream(mitogen.core.Stream):
         #: during disconnection.
         self.routes = set([self.remote_id])
 
-    def construct(self, remote_name=None, python_path=None, debug=False,
-                  connect_timeout=None, profiling=False,
+    def construct(self, max_message_size, remote_name=None, python_path=None,
+                  debug=False, connect_timeout=None, profiling=False,
                   old_router=None, **kwargs):
         """Get the named context running on the local machine, creating it if
         it does not exist."""
         super(Stream, self).construct(**kwargs)
+        self.max_message_size = max_message_size
         if python_path:
             self.python_path = python_path
         if sys.platform == 'darwin' and self.python_path == '/usr/bin/python':
@@ -367,6 +372,7 @@ class Stream(mitogen.core.Stream):
         self.remote_name = remote_name
         self.debug = debug
         self.profiling = profiling
+        self.max_message_size = max_message_size
         self.connect_deadline = time.time() + self.connect_timeout
 
     def on_shutdown(self, broker):
@@ -441,6 +447,7 @@ class Stream(mitogen.core.Stream):
         ]
 
     def get_main_kwargs(self):
+        assert self.max_message_size is not None
         parent_ids = mitogen.parent_ids[:]
         parent_ids.insert(0, mitogen.context_id)
         return {
@@ -451,6 +458,7 @@ class Stream(mitogen.core.Stream):
             'log_level': get_log_level(),
             'whitelist': self._router.get_module_whitelist(),
             'blacklist': self._router.get_module_blacklist(),
+            'max_message_size': self.max_message_size,
         }
 
     def get_preamble(self):
@@ -703,7 +711,9 @@ class Router(mitogen.core.Router):
     def _connect(self, klass, name=None, **kwargs):
         context_id = self.allocate_id()
         context = self.context_class(self, context_id)
-        stream = klass(self, context_id, old_router=self, **kwargs)
+        kwargs['old_router'] = self
+        kwargs['max_message_size'] = self.max_message_size
+        stream = klass(self, context_id, **kwargs)
         if name is not None:
             stream.name = name
         stream.connect()

tests/router_test.py

@@ -1,4 +1,6 @@
 import Queue
+import StringIO
+import logging
 import subprocess
 import time
 
@@ -8,7 +10,16 @@ import testlib
 import mitogen.master
 import mitogen.utils
 
-mitogen.utils.log_to_file()
+
+@mitogen.core.takes_router
+def return_router_max_message_size(router):
+    return router.max_message_size
+
+
+def send_n_sized_reply(sender, n):
+    sender.send(' ' * n)
+    return 123
+
 
 class AddHandlerTest(unittest2.TestCase):
     klass = mitogen.master.Router
@@ -21,6 +32,44 @@ class AddHandlerTest(unittest2.TestCase):
         self.assertEquals(queue.get(timeout=5), mitogen.core._DEAD)
 
 
+class MessageSizeTest(testlib.BrokerMixin, unittest2.TestCase):
+    klass = mitogen.master.Router
+
+    def test_local_exceeded(self):
+        router = self.klass(broker=self.broker, max_message_size=4096)
+        recv = mitogen.core.Receiver(router)
+
+        logs = testlib.LogCapturer()
+        logs.start()
+
+        sem = mitogen.core.Latch()
+        router.route(mitogen.core.Message.pickled(' '*8192))
+        router.broker.defer(sem.put, ' ')  # wlil always run after _async_route
+        sem.get()
+
+        expect = 'message too large (max 4096 bytes)'
+        self.assertTrue(expect in logs.stop())
+
+    def test_remote_configured(self):
+        router = self.klass(broker=self.broker, max_message_size=4096)
+        remote = router.fork()
+        size = remote.call(return_router_max_message_size)
+        self.assertEquals(size, 4096)
+
+    def test_remote_exceeded(self):
+        # Ensure new contexts receive a router with the same value.
+        router = self.klass(broker=self.broker, max_message_size=4096)
+        recv = mitogen.core.Receiver(router)
+
+        logs = testlib.LogCapturer()
+        logs.start()
+
+        remote = router.fork()
+        remote.call(send_n_sized_reply, recv.to_sender(), 8192)
+
+        expect = 'message too large (max 4096 bytes)'
+        self.assertTrue(expect in logs.stop())
+
+
 if __name__ == '__main__':
     unittest2.main()
-

tests/testlib.py

@@ -1,4 +1,6 @@
 
+import StringIO
+import logging
 import os
 import random
 import re
@@ -113,6 +115,24 @@ def wait_for_port(
                                  % (host, port))
 
 
+class LogCapturer(object):
+    def __init__(self, name=None):
+        self.sio = StringIO.StringIO()
+        self.logger = logging.getLogger(name)
+        self.handler = logging.StreamHandler(self.sio)
+        self.old_propagate = self.logger.propagate
+        self.old_handlers = self.logger.handlers
+
+    def start(self):
+        self.logger.handlers = [self.handler]
+        self.logger.propagate = False
+
+    def stop(self):
+        self.logger.handlers = self.old_handlers
+        self.logger.propagate = self.old_propagate
+        return self.sio.getvalue()
+
+
 class TestCase(unittest2.TestCase):
     def assertRaises(self, exc, func, *args, **kwargs):
         """Like regular assertRaises, except return the exception that was
@@ -156,19 +176,25 @@ class DockerizedSshDaemon(object):
         self.container.remove()
 
 
-class RouterMixin(object):
+class BrokerMixin(object):
     broker_class = mitogen.master.Broker
-    router_class = mitogen.master.Router
 
     def setUp(self):
-        super(RouterMixin, self).setUp()
+        super(BrokerMixin, self).setUp()
         self.broker = self.broker_class()
-        self.router = self.router_class(self.broker)
 
     def tearDown(self):
         self.broker.shutdown()
         self.broker.join()
-        super(RouterMixin, self).tearDown()
+        super(BrokerMixin, self).tearDown()
+
+
+class RouterMixin(BrokerMixin):
+    router_class = mitogen.master.Router
+
+    def setUp(self):
+        super(RouterMixin, self).setUp()
+        self.router = self.router_class(self.broker)
 
 
 class DockerMixin(RouterMixin):