add all files from Hong

plugins/ipv6only/plugin.go

@@ -0,0 +1,64 @@
+// 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 ipv6only
+
+// This plugin implements RFC8925: if the client has requested the
+// IPv6-Only Preferred option, then add the option response and then
+// terminate processing immediately.
+//
+// This module should be invoked *before* any IP address
+// allocation has been done, so that the yiaddr is 0.0.0.0 and
+// no pool addresses are consumed for compatible clients.
+//
+// The optional argument is the V6ONLY_WAIT configuration variable,
+// described in RFC8925 section 3.2.
+
+import (
+	"errors"
+	"time"
+
+	"github.com/coredhcp/coredhcp/handler"
+	"github.com/coredhcp/coredhcp/logger"
+	"github.com/coredhcp/coredhcp/plugins"
+	"github.com/insomniacslk/dhcp/dhcpv4"
+	"github.com/sirupsen/logrus"
+)
+
+var log = logger.GetLogger("plugins/ipv6only")
+
+var v6only_wait time.Duration
+
+var Plugin = plugins.Plugin{
+	Name:   "ipv6only",
+	Setup4: setup4,
+}
+
+func setup4(args ...string) (handler.Handler4, error) {
+	if len(args) > 0 {
+		dur, err := time.ParseDuration(args[0])
+		if err != nil {
+			log.Errorf("invalid duration: %v", args[0])
+			return nil, errors.New("ipv6only failed to initialize")
+		}
+		v6only_wait = dur
+	}
+	if len(args) > 1 {
+		return nil, errors.New("too many arguments")
+	}
+	return Handler4, nil
+}
+
+func Handler4(req, resp *dhcpv4.DHCPv4) (*dhcpv4.DHCPv4, bool) {
+	v6pref := req.IsOptionRequested(dhcpv4.OptionIPv6OnlyPreferred)
+	log.WithFields(logrus.Fields{
+		"mac":      req.ClientHWAddr.String(),
+		"ipv6only": v6pref,
+	}).Debug("ipv6only status")
+	if v6pref {
+		resp.UpdateOption(dhcpv4.OptIPv6OnlyPreferred(v6only_wait))
+		return resp, true
+	}
+	return resp, false
+}