[PATCH 13/16] net_reader: no STARTTLS for IMAP localhost or onions

[Eric Wong <e@80x24.org>]

At least not by default, to match existing NNTP behavior.
Tor .onions are already encrypted, and there's no point
in encrypting traffic on localhost outside of testing.
---
 lib/PublicInbox/NetReader.pm | 20 +++++++++++---------
 t/imapd-tls.t                | 11 +++++++++--
 t/nntpd-tls.t                |  8 ++++++++
 3 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/lib/PublicInbox/NetReader.pm b/lib/PublicInbox/NetReader.pm
index 236e824c..e305523e 100644
--- a/lib/PublicInbox/NetReader.pm
+++ b/lib/PublicInbox/NetReader.pm
@@ -91,6 +91,16 @@ try configuring a socks5h:// proxy:
 EOM
 }
 
+# Net::NNTP doesn't support CAPABILITIES, yet; and both IMAP+NNTP
+# servers may have multiple listen sockets.
+sub try_starttls ($) {
+	my ($host) = @_;
+	return if $host =~ /\.onion\z/si;
+	return if $host =~ /\A127\.[0-9]+\.[0-9]+\.[0-9]+\z/s;
+	return if $host eq '::1';
+	1;
+}
+
 # mic_for may prompt the user and store auth info, prepares mic_get
 sub mic_for ($$$$) { # mic = Mail::IMAPClient
 	my ($self, $uri, $mic_common, $lei) = @_;
@@ -122,6 +132,7 @@ sub mic_for ($$$$) { # mic = Mail::IMAPClient
 	# it to be disabled since I usually connect to localhost
 	if (!$mic_arg->{Ssl} && !defined($mic_arg->{Starttls}) &&
 			$mic->has_capability('STARTTLS') &&
+			try_starttls($host) &&
 			$mic->can('starttls')) {
 		$mic->starttls or die "E: <$uri> STARTTLS: $@\n";
 	}
@@ -164,15 +175,6 @@ sub mic_for ($$$$) { # mic = Mail::IMAPClient
 	$mic;
 }
 
-# Net::NNTP doesn't support CAPABILITIES, yet
-sub try_starttls ($) {
-	my ($host) = @_;
-	return if $host =~ /\.onion\z/s;
-	return if $host =~ /\A127\.[0-9]+\.[0-9]+\.[0-9]+\z/s;
-	return if $host eq '::1';
-	1;
-}
-
 sub nn_new ($$$) {
 	my ($nn_arg, $nntp_cfg, $uri) = @_;
 	my $nn;
diff --git a/t/imapd-tls.t b/t/imapd-tls.t
index 72ba8769..73f5112f 100644
--- a/t/imapd-tls.t
+++ b/t/imapd-tls.t
@@ -1,8 +1,8 @@
+#!perl -w
 # Copyright (C) 2020-2021 all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
 use strict;
-use warnings;
-use Test::More;
+use v5.10.1;
 use Socket qw(IPPROTO_TCP SOL_SOCKET);
 use PublicInbox::TestCommon;
 # IO::Poll is part of the standard library, but distros may split it off...
@@ -155,6 +155,13 @@ for my $args (
 	ok(sysread($slow, my $end, 4096) > 0, 'got end');
 	is(sysread($slow, my $eof, 4096), 0, 'got EOF');
 
+	test_lei(sub {
+		lei_ok qw(ls-mail-source), "imap://$starttls_addr",
+			\'STARTTLS not used by default';
+		ok(!lei(qw(ls-mail-source -c imap.starttls=true),
+			"imap://$starttls_addr"), 'STARTTLS verify fails');
+	});
+
 	SKIP: {
 		skip 'TCP_DEFER_ACCEPT is Linux-only', 2 if $^O ne 'linux';
 		my $var = eval { Socket::TCP_DEFER_ACCEPT() } // 9;
diff --git a/t/nntpd-tls.t b/t/nntpd-tls.t
index 2c09d34e..9af6c254 100644
--- a/t/nntpd-tls.t
+++ b/t/nntpd-tls.t
@@ -146,6 +146,14 @@ for my $args (
 	is(sysread($slow, my $eof, 4096), 0, 'got EOF');
 	$slow = undef;
 
+	test_lei(sub {
+		lei_ok qw(ls-mail-source), "nntp://$starttls_addr",
+			\'STARTTLS not used by default';
+		ok(!lei(qw(ls-mail-source -c nntp.starttls=true),
+			"nntp://$starttls_addr"), 'STARTTLS verify fails');
+		diag $lei_err;
+	});
+
 	SKIP: {
 		skip 'TCP_DEFER_ACCEPT is Linux-only', 2 if $^O ne 'linux';
 		my $var = eval { Socket::TCP_DEFER_ACCEPT() } // 9;