Handshake Negotiation Bug

[karknu]

When pallas acts as a responder and the remote side sends a handshake offer with InitiatorOnly=False pallas will refuse the connection and emit a "handshake version not accepted".

The correct behavior is for pallas to accept the handshake but respond with an AcceptVersion message with InitiatorOnly=True. The end result is a simplex mux bearer where pallas only runs the responder side of the miniprotocols and the remote end only runs the initiator miniprotocols.

From the network protocol spec: "diffusion mode SHOULD be initiator only if and only if any side proposes the initiator-only mode (i.e. the logical disjunction operator);", see https://ouroboros-network.cardano.intersectmbo.org/pdfs/network-spec/network-spec.pdf

[scarmuega]

@karknu thanks for reporting. Your description makes sense. Seems that the problem is the naive comparison of handshake params that we're doing here:

pallas/pallas-network/src/miniprotocols/handshake/server.rs

Line 137 in df1cd7a

if ver_data == client_ver_data {

I'm flagging this as a bug and adding it to the bugfix backlog.