captiveportal: avoid using /usr/bin/openssl for vouchers

We do not want to use OpenSSL from base and it may go away at
some point as well, breaking e.g. this page.  Instead, use the
internal tools or the OpenSSL plugin.  More of this on the way.

src/www/services_captiveportal_vouchers.php

 <?php
+
 /*
 	Copyright (C) 2014-2015 Deciso B.V.
 	Copyright (C) 2007 Marcel Wiget <mwiget@mac.com>
@@ -26,15 +27,16 @@
 	POSSIBILITY OF SUCH DAMAGE.
 */
 
-if ($_POST['postafterlogin'])
-	$nocsrf= true;
+if ($_POST['postafterlogin']) {
+	$nocsrf = true;
+}
 
-require("guiconfig.inc");
-require("functions.inc");
-require_once("filter.inc");
-require("shaper.inc");
-require("captiveportal.inc");
-require_once("voucher.inc");
+require_once('guiconfig.inc');
+require_once('functions.inc');
+require_once('filter.inc');
+require_once('shaper.inc');
+require_once('captiveportal.inc');
+require_once('voucher.inc');
 
 $referer = (isset($_SERVER['HTTP_REFERER']) ? $_SERVER['HTTP_REFERER'] : '/services_captiveportal_vouchers.php');
 
@@ -47,19 +49,21 @@ if (empty($cpzone)) {
         exit;
 }
 
-if($_REQUEST['generatekey']) {
-	exec("/usr/bin/openssl genrsa 64 > /tmp/key64.private");
-	exec("/usr/bin/openssl rsa -pubout < /tmp/key64.private > /tmp/key64.public");
-	$privatekey = str_replace("\n", "\\n", file_get_contents("/tmp/key64.private"));
-	$publickey = str_replace("\n", "\\n", file_get_contents("/tmp/key64.public"));
-	exec("rm /tmp/key64.private /tmp/key64.public");
-	$alertmessage = gettext("You will need to recreate any existing Voucher Rolls due to the public and private key changes. Click cancel if you do not wish to recreate the vouchers.");
-	echo json_encode(array(
-		'alertmessage' => $alertmessage,
-		'privatekey' => $privatekey,
-		'publickey' => $publickey,
-	));
-	exit;
+function generatekey($exponent)
+{
+	$ret = array();
+
+	/* generate a random 64 bit RSA key pair using the voucher binary */
+	$fd = popen(sprintf('/usr/local/bin/voucher -g 64 -e %s', $exponent), 'r');
+	if ($fd !== false) {
+		$output = fread($fd, 16384);
+		pclose($fd);
+		list($privkey, $pubkey) = explode("\0", $output);
+		$ret['priv'] = $privkey;
+		$ret['pub'] = $pubkey;
+	}
+
+	return $ret;
 }
 
 if (!is_array($config['captiveportal']))
@@ -103,16 +107,28 @@ if (!isset($config['voucher'][$cpzone]['exponent'])) {
 	unset($exponent);
 }
 
+if ($_REQUEST['generatekey']) {
+	$key = generatekey($config['voucher'][$cpzone]['exponent']);
+
+	$alertmessage = _(
+		'You will need to recreate any existing Voucher Rolls due ' .
+		'to the public and private key changes. Click cancel if you ' .
+		'do not wish to recreate the vouchers.'
+	);
+
+	echo json_encode(array(
+		'alertmessage' => $alertmessage,
+		'privatekey' => $key['priv'],
+		'publickey' => $key['pub'],
+	));
+
+	exit;
+}
+
 if (!isset($config['voucher'][$cpzone]['publickey'])) {
-	/* generate a random 64 bit RSA key pair using the voucher binary */
-	$fd = popen("/usr/local/bin/voucher -g 64 -e " . $config['voucher'][$cpzone]['exponent'], "r");
-	if ($fd !== false) {
-		$output = fread($fd, 16384);
-		pclose($fd);
-		list($privkey, $pubkey) = explode("\0", $output);
-		$config['voucher'][$cpzone]['publickey'] = base64_encode($pubkey);
-		$config['voucher'][$cpzone]['privatekey'] = base64_encode($privkey);
-	}
+	$key = generatekey($config['voucher'][$cpzone]['exponent']);
+	$config['voucher'][$cpzone]['publickey'] = base64_encode($key['pub']);
+	$config['voucher'][$cpzone]['privatekey'] = base64_encode($key['priv']);
 }
 
 // Check for invalid or expired vouchers
@@ -407,7 +423,6 @@ function enable_change(enable_change) {
 	for(var x=0; x < <?php echo count($a_roll); ?>; x++)
 		jQuery('#addeditdelete' + x).show();
 	jQuery('#addnewroll').show();
-	//}
 }
 //]]>
 </script>