fix: DoS vector in kcp accept #469
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Previously, if a client sends a hello and nothing else, the server waits to complete the handshake before accepting other connections. This opens a very easy to exploit DoS vector. Now, the server fires a separate task for completing the handshake for each client. So if a client does not cooperate with the handshake, other clients can still be accepted
Lymdun
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Nov 3, 2020
Lymdun
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## [56.4.1](v56.4.0...v56.4.1) (2020-11-03) ### Bug Fixes * DoS vector in kcp accept ([#469](#469)) ([6964bc6](6964bc6))
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🎉 This PR is included in version 56.4.1 🎉 The release is available on GitHub release Your semantic-release bot 📦🚀 |
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Actually we did not really have a problem in KCP, because the server accepts a connection after only 1 message received. This would be a problem if there was back and forth such as websocket. That said, this will be needed to support stackable handshakes, or if we want to add a challenge/response handshake in the future. |
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Previously, if a client sends a valid hello and nothing else,
the server waits to complete the handshake before accepting other connections.
This opens a very easy to exploit DoS vector, because a single client can prevent the server from accepting other connections.
Now, the server fires a separate task for completing the handshake for each client. It does not consider the connection accepted until the handshake is completed.
This way, if a client does not cooperate with the handshake, other clients can still be accepted