While dialback is in progress, we can assume that SASL external will fail anyway and can skip that step. This solves that issue and is a reasonable solution.

Looks sensible though it should be included in master branch.

@andrzej.wojcik

I was looking at this change while looking at #issue #1111 and I think we could change this condition to OR:

if (certCheckResult == CertCheckResult.invalid && serv.isHandshakingOnly()) {
	return true;
}

(if it's handshakingOnly then it's most likely dialback, and if certificate is invalid then possibly we will be able to establish s2s as a client but return connection will definitely fail. What do you think?

Well, we could try that. I've added && as I was no sure if the usage of || will not make it too relaxed and wanted to make the smallest possible change.

I was pondering it a little bit more and I think that with #issue #1112 and #issue #1132 we could actually stick with && with the assumption that it would still be possible to establish and authenticate connection in one way using SASL-EXTERNAL and other way around using dialback.