add all files from Hong

plugins/netmask/plugin.go

@@ -0,0 +1,62 @@
+// Copyright 2018-present the CoreDHCP Authors. All rights reserved
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+
+package netmask
+
+import (
+	"encoding/binary"
+	"errors"
+	"net"
+
+	"github.com/coredhcp/coredhcp/handler"
+	"github.com/coredhcp/coredhcp/logger"
+	"github.com/coredhcp/coredhcp/plugins"
+	"github.com/insomniacslk/dhcp/dhcpv4"
+)
+
+var log = logger.GetLogger("plugins/netmask")
+
+// Plugin wraps plugin registration information
+var Plugin = plugins.Plugin{
+	Name:   "netmask",
+	Setup4: setup4,
+}
+
+var (
+	netmask net.IPMask
+)
+
+func setup4(args ...string) (handler.Handler4, error) {
+	log.Printf("loaded plugin for DHCPv4.")
+	if len(args) != 1 {
+		return nil, errors.New("need at least one netmask IP address")
+	}
+	netmaskIP := net.ParseIP(args[0])
+	if netmaskIP.IsUnspecified() {
+		return nil, errors.New("netmask is not valid, got: " + args[0])
+	}
+	netmaskIP = netmaskIP.To4()
+	if netmaskIP == nil {
+		return nil, errors.New("expected an netmask address, got: " + args[0])
+	}
+	netmask = net.IPv4Mask(netmaskIP[0], netmaskIP[1], netmaskIP[2], netmaskIP[3])
+	if !checkValidNetmask(netmask) {
+		return nil, errors.New("netmask is not valid, got: " + args[0])
+	}
+	log.Printf("loaded client netmask")
+	return Handler4, nil
+}
+
+//Handler4 handles DHCPv4 packets for the netmask plugin
+func Handler4(req, resp *dhcpv4.DHCPv4) (*dhcpv4.DHCPv4, bool) {
+	resp.Options.Update(dhcpv4.OptSubnetMask(netmask))
+	return resp, false
+}
+
+func checkValidNetmask(netmask net.IPMask) bool {
+	netmaskInt := binary.BigEndian.Uint32(netmask)
+	x := ^netmaskInt
+	y := x + 1
+	return (y & x) == 0
+}

plugins/netmask/plugin_test.go

@@ -0,0 +1,65 @@
+// Copyright 2018-present the CoreDHCP Authors. All rights reserved
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+
+package netmask
+
+import (
+	"net"
+	"testing"
+
+	"github.com/insomniacslk/dhcp/dhcpv4"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCheckValidNetmask(t *testing.T) {
+	assert.True(t, checkValidNetmask(net.IPv4Mask(255, 255, 255, 0)))
+	assert.True(t, checkValidNetmask(net.IPv4Mask(255, 255, 0, 0)))
+	assert.True(t, checkValidNetmask(net.IPv4Mask(255, 0, 0, 0)))
+	assert.True(t, checkValidNetmask(net.IPv4Mask(0, 0, 0, 0)))
+
+	assert.False(t, checkValidNetmask(net.IPv4Mask(0, 255, 255, 255)))
+	assert.False(t, checkValidNetmask(net.IPv4Mask(0, 0, 255, 255)))
+	assert.False(t, checkValidNetmask(net.IPv4Mask(0, 0, 0, 255)))
+}
+
+func TestHandler4(t *testing.T) {
+	// set plugin netmask
+	netmask = net.IPv4Mask(255, 255, 255, 0)
+
+	// prepare DHCPv4 request
+	req := &dhcpv4.DHCPv4{}
+	resp := &dhcpv4.DHCPv4{
+		Options: dhcpv4.Options{},
+	}
+
+	// if we handle this DHCP request, the netmask should be one of the options
+	// of the result
+	result, stop := Handler4(req, resp)
+	assert.Same(t, result, resp)
+	assert.False(t, stop)
+	assert.EqualValues(t, netmask, resp.Options.Get(dhcpv4.OptionSubnetMask))
+}
+
+func TestSetup4(t *testing.T) {
+	// valid configuration
+	_, err := setup4("255.255.255.0")
+	assert.NoError(t, err)
+	assert.EqualValues(t, netmask, net.IPv4Mask(255, 255, 255, 0))
+
+	// no configuration
+	_, err = setup4()
+	assert.Error(t, err)
+
+	// unspecified netmask
+	_, err = setup4("0.0.0.0")
+	assert.Error(t, err)
+
+	// ipv6 prefix
+	_, err = setup4("ff02::/64")
+	assert.Error(t, err)
+
+	// invalid netmask
+	_, err = setup4("0.0.0.255")
+	assert.Error(t, err)
+}