limit dhcp range with BitMapMax

Signed-off-by: Petr Fedchenkov <giggsoff@gmail.com>
(cherry picked from commit cb9debb)

pkg/pillar/cmd/zedagent/parseconfig.go

@@ -1944,6 +1944,12 @@ func parseIpspec(ipspec *zconfig.Ipspec,
 		return fmt.Errorf("gateway(%s) inside Dhcp Range",
 			config.Gateway.String())
 	}
+	addressesInRange := config.DhcpRange.Size()
+	// we cannot use more than types.BitMapMax IPs for dynamic allocation
+	// and should keep some place in the end for static IPs assignment
+	if addressesInRange > types.BitMapMax {
+		config.DhcpRange.End = types.AddToIP(config.DhcpRange.Start, types.BitMapMax)
+	}
 	return nil
 }
 

pkg/pillar/types/zedroutertypes.go

@@ -5,6 +5,7 @@ package types
 
 import (
 	"bytes"
+	"encoding/binary"
 	"errors"
 	"fmt"
 	"net"
@@ -2053,6 +2054,22 @@ func (ipRange IpRange) Contains(ipAddr net.IP) bool {
 	return false
 }
 
+// Size returns addresses count inside IpRange
+func (ipRange IpRange) Size() uint32 {
+	//TBD:XXX, IPv6 handling
+	ip1v4 := ipRange.Start.To4()
+	ip2v4 := ipRange.End.To4()
+	if ip1v4 == nil || ip2v4 == nil {
+		return 0
+	}
+	ip1Int := binary.BigEndian.Uint32(ip1v4)
+	ip2Int := binary.BigEndian.Uint32(ip2v4)
+	if ip1Int > ip2Int {
+		return ip1Int - ip2Int
+	}
+	return ip2Int - ip1Int
+}
+
 func (config NetworkXObjectConfig) Key() string {
 	return config.UUID.String()
 }