imap: support 8000 octet lines

RFC 2683 section 3.2.1.5 recommends it:

> For its part, a server should allow for a command line of at least
> 8000 octets.  This provides plenty of leeway for accepting reasonable
> length commands from clients.  The server should send a BAD response
> to a command that does not end within the server's maximum accepted
> command length.

To conserve memory, we won't bother reading the entire line
before sending the BAD response and disconnecting them.

diff --git a/Documentation/standards.perl b/Documentation/standards.perl
index 8fc852c722bae5e48d6bcd3686ee29f7ea442662..b4bda8a9c06801df7be144e5606c66b7ce8017b6 100755 (executable)
--- a/Documentation/standards.perl
+++ b/Documentation/standards.perl
@@ -44,6 +44,7 @@ my $rfcs = [
        5322 => 'Internet message format (2008)',
        3501 => 'IMAP4rev1',
        2177 => 'IMAP IDLE',
+       2683 => 'IMAP4 Implementation Recommendations',
        # 5032 = 'WITHIN search extension for IMAP',
        4978 => 'IMAP COMPRESS Extension',
        # 5182 = 'IMAP Extension for Referencing the Last SEARCH Result',

diff --git a/lib/PublicInbox/IMAP.pm b/lib/PublicInbox/IMAP.pm
index b3c449b0712778b571ab2cbbb0d5e24b72e53c65..2e50415de57367b4f6b996c1f372ff21f1042ceb 100644 (file)
--- a/lib/PublicInbox/IMAP.pm
+++ b/lib/PublicInbox/IMAP.pm
@@ -36,7 +36,7 @@ for my $mod (qw(Email::Address::XS Mail::Address)) {
 }
 die "neither Email::Address::XS nor Mail::Address loaded: $@" if !$Address;
 
-sub LINE_MAX () { 512 } # does RFC 3501 have a limit like RFC 977?
+sub LINE_MAX () { 8000 } # RFC 2683 3.2.1.5
 
 # changing this will cause grief for clients which cache
 sub UID_BLOCK () { 50_000 }
@@ -1170,7 +1170,10 @@ sub event_step {
        my $rbuf = $self->{rbuf} // \(my $x = '');
        my $line = index($$rbuf, "\n");
        while ($line < 0) {
-               return $self->close if length($$rbuf) >= LINE_MAX;
+               if (length($$rbuf) >= LINE_MAX) {
+                       $self->write(\"\* BAD request too long\r\n");
+                       return $self->close;
+               }
                $self->do_read($rbuf, LINE_MAX, length($$rbuf)) or return;
                $line = index($$rbuf, "\n");
        }