Comment 209 for bug 296867

Corner cases:

What happens when we try to send a message and the channel is already TRUST_FINISHED? I think we should refuse, for the rest of the lifetime of that channel (until Close()), to avoid the security flaw where we send messages to a channel that just closed.

What happens when we close a channel locally? I think the answer should be "we terminate the OTR session, and start from an unsecured state next time" - even if the channel is in fact going to respawn due to unacknowledged messages. This means the channel needs to reset its Encrypted flag, Verified flag and all OTR state when it respawns. We will still be able to tell the rescued messages were encrypted/verified because the header that I suggested adding will say so.

What happens if I'm talking to <email address hidden>/Laptop using OTR, and I receive a message from <email address hidden>/Phone without OTR? I hope the answer is "libotr deals with it and reports OTRL_MSGEVENT_RCVDMSG_UNENCRYPTED". Is it safe (as in, not a security vulnerability) to rely on that?

What happens when we receive a message and the channel is already TRUST_FINISHED? I hope the answer is "libotr deals with it and reports OTRL_MSGEVENT_RCVDMSG_UNENCRYPTED". Is it safe (as in, not a security vulnerability) to rely on that?