Fix to make sure the mail URL uses a well-known host name

miniserv.pl

@@ -6,6 +6,7 @@ package miniserv;
 use Socket;
 use POSIX;
 use Time::Local;
+use Fcntl qw(LOCK_EX LOCK_UN);
 eval "use Time::HiRes;";
 
 @itoa64 = split(//, "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz");
@@ -401,6 +402,9 @@ unlink($config{'restartflag'}) if ($config{'restartflag'});
 unlink($config{'reloadflag'}) if ($config{'reloadflag'});
 unlink($config{'stopflag'}) if ($config{'stopflag'});
 
+# Cleanup well known hosts
+&cleanup_wellknown();
+
 # Build list of sockets to listen on
 @listening_on_ports = ();
 $config{'bind'} = '' if ($config{'bind'} eq '*');
@@ -4823,6 +4827,7 @@ if (defined(&Net::SSLeay::get_servername)) {
 			$h =~ /^[^\.]+\.(.*)$/ && $ssl_contexts{"*.$1"};
 		if ($c) {
 			$ssl_ctx = $c;
+			&update_wellknown_file($h);
 			}
 		}
 	}
@@ -4989,6 +4994,7 @@ if (!$config{'twofactor_wrapper'}) {
 $config{'restartflag'} ||= $var_dir."/restart-flag";
 $config{'reloadflag'} ||= $var_dir."/reload-flag";
 $config{'stopflag'} ||= $var_dir."/stop-flag";
+$config{'wellknown'} ||= $var_dir."/well-known";
 }
 
 # read_users_file()
@@ -6186,6 +6192,59 @@ close(BLOCKED);
 chmod(0700, $config{'blockedfile'});
 }
 
+# update_wellknown_file(hostname)
+# Writes out a text file of well-known hosts
+sub update_wellknown_file
+{
+my ($h) = @_;
+return if !$h;
+
+my $path = $config{'wellknown'};
+
+my $lock = "$path.lock";
+open(my $lk, ">>", $lock) or return;
+flock($lk, 2);
+
+# Read current set
+my %set;
+if (-r $path && open(my $in, "<", $path)) {
+	local $/ = undef;
+	my $raw = <$in>;
+	close $in;
+	$raw //= '';
+	$set{ $_ } = 1 for grep { length } split(/\s+/, $raw);
+	}
+
+# If already known, nothing to do
+if ($set{$h}) {
+	flock($lk, 8);
+	close($lk);
+	return;
+	}
+
+# Add and write out
+$set{$h} = 1;
+my $tmp = "$path.$$." . int(rand(1_000_000)) . ".tmp";
+if (open(my $out, ">", $tmp)) {
+	print $out join(" ", sort keys %set), "\n";
+	close $out;
+	chmod 0700, $tmp;
+	rename $tmp, $path or unlink $tmp;
+	}
+
+flock($lk, 8);
+close($lk);
+}
+
+sub cleanup_wellknown
+{
+my $path = $config{'wellknown'};
+for my $f ($path, "$path.lock") {
+	next unless -e $f;
+	unlink $f;
+	}
+}
+
 sub write_pid_file
 {
 open(PIDFILE, ">$config{'pidfile'}");