Remove DHCP leases for MAC addresses that now have static/fixed addresses. If these are not cleared, DHCP complains in the logs about duplicate leases.

1 files changed, 47 insertions, 0 deletions

diff --git a/usr/local/www/services_dhcp.php b/usr/local/www/services_dhcp.php
index 59b3415..e7f70f6 100755
--- a/usr/local/www/services_dhcp.php
+++ b/usr/local/www/services_dhcp.php
@@ -43,6 +43,50 @@ if(!$g['services_dhcp_server_enable']) {
 	exit;
 }
 
+/* This function will remove entries from dhcpd.leases that would otherwise
+ * overlap with static DHCP reservations. If we don't clean these out,
+ * then DHCP will print a warning in the logs about a duplicate lease
+ */
+function dhcp_clean_leases() {
+	global $g, $config;
+	$leasesfile = "{$g['dhcpd_chroot_path']}/var/db/dhcpd.leases";
+	/* Build list of static MACs */
+	$staticmacs = array();
+	foreach($config['interfaces'] as $ifname => $ifarr)
+		if (is_array($config['dhcpd'][$ifname]['staticmap']))
+			foreach($config['dhcpd'][$ifname]['staticmap'] as $static)
+				$staticmacs[] = $static['mac'];
+	/* Read existing leases */
+	$leases_contents = explode("\n", file_get_contents($leasesfile));
+	$newleases_contents = array();
+	$i=0;
+	while ($i < count($leases_contents)) {
+		/* Find a lease definition */
+		if (substr($leases_contents[$i], 0, 6) == "lease ") {
+			$templease = array();
+			$thismac = "";
+			/* Read to the end of the lease declaration */
+			do {
+				if (substr($leases_contents[$i], 0, 20) == "  hardware ethernet ")
+					$thismac = substr($leases_contents[$i], 20, 17);
+				$templease[] = $leases_contents[$i];
+				$i++;
+			} while ($leases_contents[$i-1] != "}");
+			/* Check for a matching MAC address and if not present, keep it. */
+			if (! in_array($thismac, $staticmacs))
+				$newleases_contents = array_merge($newleases_contents, $templease);
+		} else {
+			/* It's a line we want to keep, copy it over. */
+			$newleases_contents[] = $leases_contents[$i];
+			$i++;
+		}
+	}
+	/* Write out the new leases file */
+	$fd = fopen($leasesfile, 'w');
+	fwrite($fd, implode("\n", $newleases_contents));
+	fclose($fd);
+}
+
 $if = $_GET['if'];
 if ($_POST['if'])
 	$if = $_POST['if'];
@@ -259,6 +303,9 @@ if ($_POST) {
 		$retvaldhcp = 0;
 		$retvaldns = 0;
 		config_lock();
+		/* Stop DHCP so we can cleanup leases */
+		killbyname("dhcpd");
+		dhcp_clean_leases();
 		/* dnsmasq_configure calls dhcpd_configure */
 		/* no need to restart dhcpd twice */
 		if (isset($config['dnsmasq']['regdhcpstatic']))	{