Improve processing of DNS server changes

What a pain this was. The user can blank out a DNS server from a position in the middle of the list. e.g. they had all 4 entries previously filled, and then they blank out DNS server #3. The way the DNS servers are stored in the config, they are just the defined ones in an "un-indexed" array. So actually entries 1, 2 and 4 on the screen become 1st, 2nd and 3rd in the config. The selected gateways for 1, 2 and 4 then have to end up in positions 1, 2 and 3 to match the stored DNS servers.
This fixes all that up, as well as allowing the user to leave a gateway selected against a blanked-out DNS server entry - in that case the whole entry is "removed/ignored".

1 files changed, 35 insertions, 8 deletions

diff --git a/usr/local/www/system.php b/usr/local/www/system.php
index a5028c6..ead4700 100755
--- a/usr/local/www/system.php
+++ b/usr/local/www/system.php
@@ -115,6 +115,8 @@ if ($_POST) {
 		$input_errors[] = gettext("The domain may only contain the characters a-z, 0-9, '-' and '.'.");
 	}
 
+	$ignore_posted_dnsgw = array();
+
 	for ($dnscounter=1; $dnscounter<5; $dnscounter++){
 		$dnsname="dns{$dnscounter}";
 		$dnsgwname="dns{$dnscounter}gw";
@@ -131,8 +133,8 @@ if ($_POST) {
 						$input_errors[] = gettext("You can not specify IPv4 gateway '{$_POST[$dnsgwname]}' for IPv6 DNS server '{$_POST[$dnsname]}'");
 					}
 				} else {
-					// The user selected a gateway but did not provide a DNS address.
-					$input_errors[] = gettext("A valid IP address must be specified for DNS server $dnscounter when a gateway is selected.");
+					// The user selected a gateway but did not provide a DNS address. Be nice and set the gateway back to "none".
+					$ignore_posted_dnsgw[$dnsgwname] = true;
 				}
 			}
 		}
@@ -212,17 +214,40 @@ if ($_POST) {
 			unset($config['system']['dnslocalhost']);
 
 		/* which interface should the dns servers resolve through? */
+		$outdnscounter = 0;
 		for ($dnscounter=1; $dnscounter<5; $dnscounter++) {
 			$dnsname="dns{$dnscounter}";
 			$dnsgwname="dns{$dnscounter}gw";
 			$olddnsgwname = $config['system'][$dnsgwname];
-			if($_POST[$dnsgwname]) {
-				$config['system'][$dnsgwname] = $pconfig[$dnsgwname];
-			} else {
-				// Note: when no DNS GW name is chosen, the entry is set to "none", so actually this case never happens.
-				unset($config['system'][$dnsgwname]);
+
+			if ($ignore_posted_dnsgw[$dnsgwname])
+				$thisdnsgwname = "none";
+			else
+				$thisdnsgwname = $pconfig[$dnsgwname];
+
+			// "Blank" out the settings for this index, then we set them below using the "outdnscounter" index.
+			$config['system'][$dnsgwname] = "none";
+			$pconfig[$dnsgwname] = "none";
+			$pconfig[$dnsname] = "";
+
+			if ($_POST[$dnsname]) {
+				// Only the non-blank DNS servers were put into the config above.
+				// So we similarly only add the corresponding gateways sequentially to the config (and to pconfig), as we find non-blank DNS servers.
+				// This keeps the DNS server IP and corresponding gateway "lined up" when the user blanks out a DNS server IP in the middle of the list.
+				$outdnscounter++;
+				$outdnsname="dns{$outdnscounter}";
+				$outdnsgwname="dns{$outdnscounter}gw";
+				$pconfig[$outdnsname] = $_POST[$dnsname];
+				if($_POST[$dnsgwname]) {
+					$config['system'][$outdnsgwname] = $thisdnsgwname;
+					$pconfig[$outdnsgwname] = $thisdnsgwname;
+				} else {
+					// Note: when no DNS GW name is chosen, the entry is set to "none", so actually this case never happens.
+					unset($config['system'][$outdnsgwname]);
+					$pconfig[$outdnsgwname] = "";
+				}
 			}
-			if (($olddnsgwname != "") && ($olddnsgwname != "none") && (($olddnsgwname != $config['system'][$dnsgwname]) || ($olddnsservers[$dnscounter-1] != $dnsname))) {
+			if (($olddnsgwname != "") && ($olddnsgwname != "none") && (($olddnsgwname != $thisdnsgwname) || ($olddnsservers[$dnscounter-1] != $_POST[$dnsname]))) {
 				// A previous DNS GW name was specified. It has now gone or changed, or the DNS server address has changed.
 				// Remove the route. Later calls will add the correct new route if needed.
 				if (is_ipaddrv4($olddnsservers[$dnscounter-1]))
@@ -252,6 +277,8 @@ if ($_POST) {
 		
 		$savemsg = get_std_save_message($retval);
 	}
+
+	unset($ignore_posted_dnsgw);
 }
 
 $pgtitle = array(gettext("System"),gettext("General Setup"));