Fix 'compress migrate' for 2.2 clients.

Fix 'compress migrate' for 2.2 clients.

Commit 8fa8a17528c001a introduces "compress migrate" to move old clients
that have "compress" or "comp-lzo" in their config towards a connection
without compression.  This is done by looking at incoming OCC strings
to see if the client has compression enabled, and at incoming IV_
strings to see whether it can do "compress stub-v2" or needs to be sent
"comp-lzo no".

That check fails for 2.2 clients that do not send *any* peer-info by
default, so the server will not push back any "disable compression"
command.  It works if the client connects with "--push-peer-info".

Fix: turn around the order of checks, treat "no peer_info" the same
as "peer_info does not contain IV_COMP_STUBv2".

Signed-off-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Arne Schwabe <arne@rfc2549.org>
Message-Id: <20210402134529.27866-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg21974.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>