From 342699d9330c75b3ce7949112ef15b0d21e9c8d1 Mon Sep 17 00:00:00 2001
From: Simon Zolin <s.zolin@adguard.com>
Date: Tue, 14 May 2019 14:50:47 +0300
Subject: [PATCH] * dhcpd: minor improvements

---
 dhcpd/db.go    | 17 +++++++++++++----
 dhcpd/dhcpd.go |  5 -----
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/dhcpd/db.go b/dhcpd/db.go
index 1caa7d81..f9c371d3 100644
--- a/dhcpd/db.go
+++ b/dhcpd/db.go
@@ -23,8 +23,20 @@ type leaseJSON struct {
 	Expiry   int64  `json:"exp"`
 }
 
+// Safe version of dhcp4.IPInRange()
+func ipInRange(start, stop, ip net.IP) bool {
+	if len(start) != len(stop) ||
+		len(start) != len(ip) {
+		return false
+	}
+	return dhcp4.IPInRange(start, stop, ip)
+}
+
 // Load lease table from DB
 func (s *Server) dbLoad() {
+	s.leases = nil
+	s.IPpool = make(map[[4]byte]net.HardwareAddr)
+
 	data, err := ioutil.ReadFile(dbFilename)
 	if err != nil {
 		if !os.IsNotExist(err) {
@@ -40,13 +52,10 @@ func (s *Server) dbLoad() {
 		return
 	}
 
-	s.leases = nil
-	s.IPpool = make(map[[4]byte]net.HardwareAddr)
-
 	numLeases := len(obj)
 	for i := range obj {
 
-		if !dhcp4.IPInRange(s.leaseStart, s.leaseStop, obj[i].IP) {
+		if !ipInRange(s.leaseStart, s.leaseStop, obj[i].IP) {
 			log.Tracef("Skipping a lease with IP %s: not within current IP range", obj[i].IP)
 			continue
 		}
diff --git a/dhcpd/dhcpd.go b/dhcpd/dhcpd.go
index 20ab4d24..85df1590 100644
--- a/dhcpd/dhcpd.go
+++ b/dhcpd/dhcpd.go
@@ -286,11 +286,6 @@ func (s *Server) findExpiredLease() int {
 }
 
 func (s *Server) findFreeIP(hwaddr net.HardwareAddr) (net.IP, error) {
-	// if IP pool is nil, lazy initialize it
-	if s.IPpool == nil {
-		s.IPpool = make(map[[4]byte]net.HardwareAddr)
-	}
-
 	// go from start to end, find unreserved IP
 	var foundIP net.IP
 	for i := 0; i < dhcp4.IPRange(s.leaseStart, s.leaseStop); i++ {