extensions: misbehaving cases

[vladopajic]

specification for gossipsub extensions, "test extension" and partial messages extension are not very well describing what should be considered as misbehavior (penalty).

for example:

• If a peer supports any extension, the Extensions control message MUST be included in the first message on the stream

  • if an extension control message is sent, but it is not the first message, is it misbehavior?

• Extensions control message MUST NOT be sent more than once

  • go-libp2p identifies this case as misbehavior

• A node MUST omit the partialMessage field of the PartialMessagesExtension message when sending a message to this peer. In other words, it MUST NOT send this peer encoded partialMessage data since it did not request it.

  • not clear if this should be misbehavior

in general, it would be better if specs had a better way of specifying what cases should be considered as misbehavior. for example, all documents (in gossipsub) could have an additional section where all misbehavior cases are listed.

[MarcoPolo]

If a peer does not fulfill a MUST, it is not implementing the protocol.

Disconnecting from the peer and penalizing their local score is the correct approach. I'm happy to accept a patch that makes this clearer.