From f40f4695c0cb576a4e00819da45c1bea8f548aec Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Wed, 20 Jul 2022 09:24:13 +0000
Subject: [PATCH] pop3: advertise STLS in CAPA if appropriate
This is documented in RFC 2595, and POP3 clients may rely on
seeing "STLS" in CAPA output to initiate TLS negotiation.
---
Documentation/standards.perl | 1 +
lib/PublicInbox/POP3.pm | 6 ++++--
t/pop3d.t | 7 +++++++
3 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/Documentation/standards.perl b/Documentation/standards.perl
index 835de3a2..c36afb5d 100755
--- a/Documentation/standards.perl
+++ b/Documentation/standards.perl
@@ -69,6 +69,7 @@ my $rfcs = [
1081 => 'Post Office Protocol â Version 3',
1939 => 'Post Office Protocol â Version 3 (STD 53)',
2449 => 'POP3 extension mechanism',
+ 2595 => 'STARTTLS for IMAP and POP3',
2384 => 'POP URL Scheme',
# TODO: flesh this out
diff --git a/lib/PublicInbox/POP3.pm b/lib/PublicInbox/POP3.pm
index 2c20c84b..ec73893c 100644
--- a/lib/PublicInbox/POP3.pm
+++ b/lib/PublicInbox/POP3.pm
@@ -343,15 +343,17 @@ sub cmd_dele {
# RFC 2449
sub cmd_capa {
my ($self) = @_;
+ my $STLS = !$self->{ibx} && !$self->{sock}->can('stop_SSL') &&
+ $self->{pop3d}->{accept_tls} ? "\nSTLS\r" : '';
$self->{expire} = ''; # "EXPIRE 0" allows clients to avoid DELE commands
- \<<EOM;
+ <<EOM;
+OK Capability list follows\r
TOP\r
USER\r
PIPELINING\r
UIDL\r
EXPIRE 0\r
-RESP-CODES\r
+RESP-CODES\r$STLS
.\r
EOM
}
diff --git a/t/pop3d.t b/t/pop3d.t
index 3d70935f..9eb110d6 100644
--- a/t/pop3d.t
+++ b/t/pop3d.t
@@ -106,6 +106,8 @@ for my $args (
my @p3s_args = ($pop3s->sockhost,
Port => $pop3s->sockport, SSL => 1, %o);
my $p3s = Net::POP3->new(@p3s_args);
+ my $capa = $p3s->capa;
+ ok(!exists $capa->{STLS}, 'no STLS CAPA for POP3S');
ok($p3s->quit, 'QUIT works w/POP3S');
{
$p3s = Net::POP3->new(@p3s_args);
@@ -127,7 +129,11 @@ for my $args (
my $np3 = Net::POP3->new(@np3_args);
ok($np3->quit, 'plain QUIT works');
$np3 = Net::POP3->new(@np3_args, %o);
+ $capa = $np3->capa;
+ ok(exists $capa->{STLS}, 'STLS CAPA advertised before STLS');
ok($np3->starttls, 'STLS works');
+ $capa = $np3->capa;
+ ok(!exists $capa->{STLS}, 'STLS CAPA not advertised after STLS');
ok($np3->quit, 'QUIT works after STLS');
for my $mailbox (('x'x32)."\@$group", $group, ('a'x32)."\@z.$group") {
@@ -239,6 +245,7 @@ EOF
my $capa = $oldc->capa;
ok(defined($capa->{PIPELINING}), 'pipelining supported by CAPA');
is($capa->{EXPIRE}, 0, 'EXPIRE 0 set');
+ ok(!exists $capa->{STLS}, 'STLS unset w/o daemon certs');
# ensure TOP doesn't trigger "EXPIRE 0" like RETR does (cf. RFC2449)
my $list = $oldc->list;
--
2.51.0