nntpd: move {newsgroup} name check to config

With 50K newsgroups in the config file, this doesn't slow down
`PublicInbox::Config->new->fill_all' any measurable amount on
my busy old workstation.

This should prevent invalid newsgroup names from getting into
into extindex and catch user errors sooner, rather than later.

v2:
  - delete {newsgroup} if invalid to avoid ->nntp_url link
  - simplify -imapd and explain remaining check

1 files changed, 17 insertions, 4 deletions

diff --git a/lib/PublicInbox/Config.pm b/lib/PublicInbox/Config.pm
index e7aea99b..9b9d5c19 100644
--- a/lib/PublicInbox/Config.pm
+++ b/lib/PublicInbox/Config.pm
@@ -437,10 +437,23 @@ EOF
                         $self->{-by_list_id}->{lc($list_id)} = $ibx;
                 }
         }
-        if (my $ng = $ibx->{newsgroup}) {
-                # PublicInbox::NNTPD does stricter (and more expensive checks),
-                # keep this lean for startup speed
-                $self->{-by_newsgroup}->{$ng} = $ibx unless ref($ng);
+        if (my $ngname = $ibx->{newsgroup}) {
+                if (ref($ngname)) {
+                        delete $ibx->{newsgroup};
+                        warn 'multiple newsgroups not supported: '.
+                                join(', ', @$ngname). "\n";
+                # Newsgroup name needs to be compatible with RFC 3977
+                # wildmat-exact and RFC 3501 (IMAP) ATOM-CHAR.
+                # Leave out a few chars likely to cause problems or conflicts:
+                # '|', '<', '>', ';', '#', '$', '&',
+                } elsif ($ngname =~ m![^A-Za-z0-9/_\.\-\~\@\+\=:]!) {
+                        delete $ibx->{newsgroup};
+                        warn "newsgroup name invalid: `$ngname'\n";
+                } else {
+                        # PublicInbox::NNTPD does stricter ->nntp_usable
+                        # checks, keep this lean for startup speed
+                        $self->{-by_newsgroup}->{$ngname} = $ibx;
+                }
         }
         $self->{-by_name}->{$name} = $ibx;
         if ($ibx->{obfuscate}) {