Namely, don't check the DNS names in TLS certificates when connecting to
other servers.
As of golang 1.3, crypto/tls no longer natively supports doing partial
verification (verifying the cert issuer but not the hostname), so we
have to disable verification entirely and then do the issuer
verification ourselves. Fortunately, crypto/x509 makes this relatively
straightforward.
If the "server_name" configuration option is passed, we preserve the
existing behavior of checking that server name everywhere.
No option is provided to retain the current behavior of checking the
remote certificate against the local node name, since that behavior
seems clearly buggy and unintentional, and I have difficulty imagining
it is actually being used anywhere. It would be relatively
straightforward to restore if desired, however.
This allows for us to automatically bootstrap a cluster of nodes after
'n' number of server nodes join. All servers must have the same 'n' set, or
they will fail to join the cluster; all servers will not join the peer set
until they hit 'n' server nodes.
If the raft commit index is not empty, '-expect=n' does nothing because it
thinks you've already bootstrapped.
Signed-off-by: Robert Xu <robxu9@gmail.com>
