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lemunozm / message-io

Fast and easy-to-use event-driven network library.
Apache License 2.0
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Is it possible to limit max packet size when using FramedTcp transport? #161

Open mengguang opened 1 year ago

mengguang commented 1 year ago

If not possible, it may lead to Deny of Service with malicious clients.

lemunozm commented 1 year ago

Yes, you're right. If the client specifies that it sends 4GB of the message, and it sends 3.9GB and maintains the connection open, the server must allocate that memory expecting the client sends the remaining 0.1GB of the message.

Once #54 has been merged, that maximum could be specified by a parameter for the FramedTcp listener. Nevertheless, I think adding a maximum only adds more work for the attacker, but it's still vulnerable. The attacker only needs to create more connections leaving incomplete messages.

I think a better solution to protect against this attack is to close the server FramedTcp connection if the endpoint is not sending more fragments when it is in the middle of building a framed message. This "timeout" could also be configured by #54 when the listener is created, even you could mix both, a maximum and a timeout.