fix(s2n-quic-transport): check initial dcid usage #1971
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| .destination_connection_id_classification | ||
| .is_initial() | ||
| { | ||
| return Err(ProcessingError::Other); |
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should we add a PacketDropReason for this and emit the PacketDropped event?
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| #[derive(Clone, Copy, Debug, PartialEq, Eq)] | ||
| pub enum Classification { | ||
| /// The connection ID was chosen by the client |
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Suggested change
| /// The connection ID was chosen by the client | |
| /// The connection ID was chosen by the peer client |
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Not sure what you mean by this suggestion... I wanted to keep this enum generic enough that it could be used by either endpoint. So it might not always be a peer. But it will always be client-chosen.
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Ah, I was thinking it was only used for classifying a connection ID seen on an incoming datagram
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It currently is limited to that. But I'd like it to be flexible for future uses, too.
WesleyRosenblum
approved these changes
Sep 20, 2023
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Description of changes:
The RFC mentions that IDCIDs should only be used in Initial and Stateless Resets.
https://www.rfc-editor.org/rfc/rfc9000#section-21.2
While it's not a MUST, SHOULD, or even a MAY, it's still good to enforce. Note that this really doesn't do much to prevent a Handshake Denial of Service, since the packets that we check are using cryptographic secrets only the peers know (i.e. Handshake, Application).
Testing:
I was able to test that this check works correctly by modifying our client to ignore the server's chosen DCID in a self-talk test. However, I'm not sure if we can easily test this with the current testing framework.
In the coming weeks, I will likely be refactoring a lot of the packet processing code to decouple it from the endpoint and connection structs. During that time, I will be setting up a better test environment for unit testing these kinds of checks.
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.