go.crypto/ssh: fix authentication after all public keys are rejected by a server.
Validating a public key doesn't return any remaining methods so, if all public keys were rejected, a nil slice would be returned for the remaining methods and authentication would stop.
We could have validateKey return methods, but that wouldn't solve the problem of what to do if the callback returns no keys. In that case we don't have any keys to test.
So this change makes it possible for an AuthMethod to return a nil slice for the remaining methods (meaning "reuse the last list"). It also fixes a scoping bug.
Fixes golang/go#7787.
LGTM=hanwen
R=hanwen
CC=golang-codereviews
https://golang.org/cl/94350043
1 file changed
