From 522666e8e2556d89c25013ce17d6db49e75443ef Mon Sep 17 00:00:00 2001
From: Guilhem Moulin <guilhem@fripost.org>
Date: Mon, 21 Jan 2019 23:59:55 +0100
Subject: Net::IMAP::InterIMAP: add support for TLSv1.3 (on recent enough
 Net::SSLeay).

Also, change "SSL_protocols" default value from "!SSLv2 !SSLv3" to
"!SSLv2 !SSLv3 !TLSv1 !TLSv1.1".  I.e., only enable TLSv1.2 and later,
which is the default in Debian's OpenSSL as of 1.1.1-2, cf.
https://tracker.debian.org/news/998835/accepted-openssl-111-2-source-into-unstable/ .
---
 lib/Net/IMAP/InterIMAP.pm | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

(limited to 'lib')

diff --git a/lib/Net/IMAP/InterIMAP.pm b/lib/Net/IMAP/InterIMAP.pm
index f783ea7..3d8bd97 100644
--- a/lib/Net/IMAP/InterIMAP.pm
+++ b/lib/Net/IMAP/InterIMAP.pm
@@ -45,7 +45,7 @@ my $RE_ATOM_CHAR    = qr/[\x21\x23\x24\x26\x27\x2B-\x5B\x5E-\x7A\x7C-\x7E]/;
 my $RE_ASTRING_CHAR = qr/[\x21\x23\x24\x26\x27\x2B-\x5B\x5D-\x7A\x7C-\x7E]/;
 my $RE_TEXT_CHAR    = qr/[\x01-\x09\x0B\x0C\x0E-\x7F]/;
 
-my $RE_SSL_PROTO = qr/(?:SSLv[23]|TLSv1|TLSv1\.[0-2])/;
+my $RE_SSL_PROTO = qr/(?:SSLv[23]|TLSv1|TLSv1\.[0-3])/;
 
 # Map each option to a regexp validating its values.
 my %OPTIONS = (
@@ -1599,13 +1599,19 @@ sub _ssl_verify($$$) {
     return $ok; # 1=accept cert, 0=reject
 }
 
-my %SSL_proto = (
-    'SSLv2' => Net::SSLeay::OP_NO_SSLv2(),
-    'SSLv3' => Net::SSLeay::OP_NO_SSLv3(),
-    'TLSv1' => Net::SSLeay::OP_NO_TLSv1(),
-    'TLSv1.1' => Net::SSLeay::OP_NO_TLSv1_1(),
-    'TLSv1.2' => Net::SSLeay::OP_NO_TLSv1_2()
-);
+my %SSL_proto;
+BEGIN {
+    sub _append_ssl_proto($$) {
+        my ($k, $v) = @_;
+        $SSL_proto{$k} = $v if defined $v;
+    }
+    _append_ssl_proto( "SSLv2",   eval { Net::SSLeay::OP_NO_SSLv2()   } );
+    _append_ssl_proto( "SSLv3",   eval { Net::SSLeay::OP_NO_SSLv3()   } );
+    _append_ssl_proto( "TLSv1",   eval { Net::SSLeay::OP_NO_TLSv1()   } );
+    _append_ssl_proto( "TLSv1.1", eval { Net::SSLeay::OP_NO_TLSv1_1() } );
+    _append_ssl_proto( "TLSv1.2", eval { Net::SSLeay::OP_NO_TLSv1_2() } );
+    _append_ssl_proto( "TLSv1.3", eval { Net::SSLeay::OP_NO_TLSv1_3() } );
+}
 
 # $self->_start_ssl($socket)
 #   Upgrade the $socket to SSL/TLS.
@@ -1614,7 +1620,7 @@ sub _start_ssl($$) {
     my $ctx = Net::SSLeay::CTX_new() or $self->panic("Failed to create SSL_CTX $!");
     my $ssl_options = Net::SSLeay::OP_SINGLE_DH_USE() | Net::SSLeay::OP_SINGLE_ECDH_USE();
 
-    $self->{SSL_protocols} //= q{!SSLv2 !SSLv3};
+    $self->{SSL_protocols} //= q{!SSLv2 !SSLv3 !TLSv1 !TLSv1.1};
     my ($proto_include, $proto_exclude) = (0, 0);
     foreach (split /\s+/, $self->{SSL_protocols}) {
         my $neg = s/^!// ? 1 : 0;
@@ -1629,7 +1635,7 @@ sub _start_ssl($$) {
         $proto_exclude |= $x;
     }
     my @proto_exclude = grep { ($proto_exclude & $SSL_proto{$_}) != 0 } keys %SSL_proto;
-    $self->log("Disabling SSL protocol: ".join(', ', sort @proto_exclude)) if $self->{debug};
+    $self->log("Disabling SSL protocols: ".join(', ', sort @proto_exclude)) if $self->{debug};
     $ssl_options |= $SSL_proto{$_} foreach @proto_exclude;
     $ssl_options |= Net::SSLeay::OP_NO_COMPRESSION();
 
@@ -1675,6 +1681,7 @@ sub _start_ssl($$) {
                                                        $v == 0x0301 ? 'TLSv1' :
                                                        $v == 0x0302 ? 'TLSv1.1' :
                                                        $v == 0x0303 ? 'TLSv1.2' :
+                                                       $v == 0x0304 ? 'TLSv1.3' :
                                                                       '??'),
                                                       $v));
         $self->log(sprintf('SSL cipher: %s (%d bits)'
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