imap: prioritize AUTH=ANONYMOUS clients

...by deprioritizing clients using a username + password.

As IMAP provides AUTH=ANONYMOUS for designating anonymous
access, we'll rely on it as a heuristic for favoring "good"
clients.  Clients using a username + password seem to (more
often than not) be malicious and looking for info which doesn't
belong in public inboxes.

This copies the technique used by WWW + -httpd to deprioritize
expensive mbox.gz downloads.

1 files changed, 10 insertions, 0 deletions

diff --git a/lib/PublicInbox/IMAP.pm b/lib/PublicInbox/IMAP.pm
index 4ef5252b..605c5e51 100644
--- a/lib/PublicInbox/IMAP.pm
+++ b/lib/PublicInbox/IMAP.pm
@@ -575,6 +575,16 @@ sub fetch_run_ops {
         $self->msg_more(")\r\n");
 }
 
+sub requeue { # overrides PublicInbox::DS::requeue
+        my ($self) = @_;
+        if ($self->{anon}) { # AUTH=ANONYMOUS gets high priority
+                $self->SUPER::requeue;
+        } else { # low priority
+                push(@{$self->{imapd}->{-authed_q}}, $self) == 1 and
+                        PublicInbox::DS::requeue($self->{imapd});
+        }
+}
+
 sub fetch_blob_cb { # called by git->cat_async via ibx_async_cat
         my ($bref, $oid, $type, $size, $fetch_arg) = @_;
         my ($self, undef, $msgs, $range_info, $ops, $partial) = @$fetch_arg;