From ccd0f07fa8e1b2313c97331cea23556b220807a8 Mon Sep 17 00:00:00 2001
From: Franco Fichtner <franco@opnsense.org>
Date: Fri, 28 Dec 2018 18:20:48 +0100
Subject: [PATCH] interfaces: clear a faulty automatic DUID; closes #3061

---
 src/etc/inc/interfaces.inc          | 13 +++------
 src/etc/inc/util.inc                | 44 +++++++++++++++++++++++++++++
 src/www/system_advanced_network.php | 22 ++-------------
 3 files changed, 50 insertions(+), 29 deletions(-)

diff --git a/src/etc/inc/interfaces.inc b/src/etc/inc/interfaces.inc
index 932d3dab5..7c5fce471 100644
--- a/src/etc/inc/interfaces.inc
+++ b/src/etc/inc/interfaces.inc
@@ -2858,15 +2858,10 @@ function interface_dhcpv6_configure($interface = 'wan', $wancfg)
 
     /* write DUID if override was set */
     if (!empty($config['system']['ipv6duid'])) {
-        $fd = fopen('/var/db/dhcp6c_duid', 'wb');
-        if ($fd) {
-            $parts = explode(':', $config['system']['ipv6duid']);
-            /* length is unsigned 16 bit integer, machine-dependent:*/
-            fwrite($fd, pack('S', count($parts)));
-            /* buffer is binary string, according to advertised length: */
-            fwrite($fd, pack('H*', implode('', $parts)));
-            fclose($fd);
-        }
+        dhcp6c_duid_write($config['system']['ipv6duid']);
+    /* clear DUID if it is faulty */
+    } elseif (empty(dhcp6c_duid_read())) {
+        dhcp6c_duid_clear();
     }
 
     if (!is_array($wancfg)) {
diff --git a/src/etc/inc/util.inc b/src/etc/inc/util.inc
index 35d0215ea..a6192754d 100644
--- a/src/etc/inc/util.inc
+++ b/src/etc/inc/util.inc
@@ -1281,3 +1281,47 @@ function is_install_media()
 
     return true;
 }
+
+function dhcp6c_duid_read()
+{
+    $parts = array();
+    $skip = 2;
+
+    if (file_exists('/var/db/dhcp6c_duid')) {
+        $size = filesize('/var/db/dhcp6c_duid');
+        if ($size > $skip && ($fd = fopen('/var/db/dhcp6c_duid', 'r'))) {
+            $ret = unpack('Slen/H*buf', fread($fd, $size));
+            fclose($fd);
+
+            if (isset($ret['len']) && isset($ret['buf'])) {
+                if ($ret['len'] + $skip == $size && strlen($ret['buf']) == $ret['len'] * 2) {
+                    $parts = str_split($ret['buf'], 2);
+                }
+            }
+        }
+    }
+
+    $duid = strtoupper(implode(':', $parts));
+
+    return $duid;
+}
+
+function dhcp6c_duid_write($duid)
+{
+    $fd = fopen('/var/db/dhcp6c_duid', 'wb');
+    if ($fd) {
+        $parts = explode(':', $duid);
+        /* length is unsigned 16 bit integer, machine-dependent:*/
+        fwrite($fd, pack('S', count($parts)));
+        /* buffer is binary string, according to advertised length: */
+        fwrite($fd, pack('H*', implode('', $parts)));
+        fclose($fd);
+    }
+}
+
+function dhcp6c_duid_clear()
+{
+    @unlink('/var/db/dhcp6c_duid');
+    /* clear the backup so that it will not be restored: */
+    @unlink('/conf/dhcp6c_duid');
+}
diff --git a/src/www/system_advanced_network.php b/src/www/system_advanced_network.php
index 0c14b061b..0678f77ab 100644
--- a/src/www/system_advanced_network.php
+++ b/src/www/system_advanced_network.php
@@ -148,24 +148,7 @@ function is_duid($duid)
 /* read duid from disk or return blank DUID string */
 function read_duid()
 {
-    $parts = array();
-    $skip = 2;
-
-    if (file_exists('/var/db/dhcp6c_duid')) {
-        $size = filesize('/var/db/dhcp6c_duid');
-        if ($size > $skip && ($fd = fopen('/var/db/dhcp6c_duid', 'r'))) {
-            $ret = unpack('Slen/H*buf', fread($fd, $size));
-            fclose($fd);
-
-            if (isset($ret['len']) && isset($ret['buf'])) {
-                if ($ret['len'] + $skip == $size && strlen($ret['buf']) == $ret['len'] * 2) {
-                    $parts = str_split($ret['buf'], 2);
-                }
-            }
-        }
-    }
-
-    $duid = strtoupper(implode(':', $parts));
+    $duid = dhcp6c_duid_read();
 
     if (!is_duid($duid)) {
         $duid = 'XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX';
@@ -235,8 +218,7 @@ if ($_SERVER['REQUEST_METHOD'] === 'GET') {
         } elseif (isset($config['system']['ipv6duid'])) {
             unset($config['system']['ipv6duid']);
             /* clear the file as this means auto-generate */
-            @unlink('/var/db/dhcp6c_duid');
-            @unlink('/conf/dhcp6c_duid');
+            dhcp6c_duid_clear();
         }
 
         $savemsg = get_std_save_message();