dco: add standard mi prefix handling to multi_process_incoming_dco()

Our code generally expects functions that deal with a multi instance
to set up a log prefix at the beginning with set_prefix(mi) and clear
it at the end with clear_prefix().

Add the calls to multi_process_incoming_dco() in a similar way to
what is done for multi_process_incoming_link() - handling "link
events" and "dco events" the same, with correct prefix in the
function and no leftover prefix afterwards.

Github: closes #799
Change-Id: I1ad5df0f6785ffe9becd9f83329a9335d1a36f24
Signed-off-by: Antonio Quartulli <[email protected]>
Signed-off-by: Gert Doering <[email protected]>
Acked-by: Gert Doering <[email protected]>
Message-Id: <[email protected]>
URL: https://www.mail-archive.com/[email protected]/msg32859.html
URL: https://gerrit.openvpn.net/c/openvpn/+/1116
Signed-off-by: Gert Doering <[email protected]>

Author: ordex

src/openvpn/multi.c

@@ -3294,6 +3294,7 @@ multi_process_incoming_dco(struct multi_context *m)
     if ((peer_id < m->max_clients) && (m->instances[peer_id]))
     {
         mi = m->instances[peer_id];
+        set_prefix(mi);
         if (dco->dco_message_type == OVPN_CMD_DEL_PEER)
         {
             process_incoming_del_peer(m, mi, dco);
@@ -3311,6 +3312,7 @@ multi_process_incoming_dco(struct multi_context *m)
         {
             tls_session_soft_reset(mi->context.c2.tls_multi);
         }
+        clear_prefix();
     }
     else
     {