add all files from Hong

plugins/dns/plugin.go

@@ -0,0 +1,83 @@
+// 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 dns
+
+import (
+	"errors"
+	"net"
+
+	"github.com/coredhcp/coredhcp/handler"
+	"github.com/coredhcp/coredhcp/logger"
+	"github.com/coredhcp/coredhcp/plugins"
+	"github.com/insomniacslk/dhcp/dhcpv4"
+	"github.com/insomniacslk/dhcp/dhcpv6"
+)
+
+var log = logger.GetLogger("plugins/dns")
+
+// Plugin wraps the DNS plugin information.
+var Plugin = plugins.Plugin{
+	Name:   "dns",
+	Setup6: setup6,
+	Setup4: setup4,
+}
+
+var (
+	dnsServers6 []net.IP
+	dnsServers4 []net.IP
+)
+
+func setup6(args ...string) (handler.Handler6, error) {
+	if len(args) < 1 {
+		return nil, errors.New("need at least one DNS server")
+	}
+	for _, arg := range args {
+		server := net.ParseIP(arg)
+		if server.To16() == nil {
+			return Handler6, errors.New("expected an DNS server address, got: " + arg)
+		}
+		dnsServers6 = append(dnsServers6, server)
+	}
+	log.Infof("loaded %d DNS servers.", len(dnsServers6))
+	return Handler6, nil
+}
+
+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 DNS server")
+	}
+	for _, arg := range args {
+		DNSServer := net.ParseIP(arg)
+		if DNSServer.To4() == nil {
+			return Handler4, errors.New("expected an DNS server address, got: " + arg)
+		}
+		dnsServers4 = append(dnsServers4, DNSServer)
+	}
+	log.Infof("loaded %d DNS servers.", len(dnsServers4))
+	return Handler4, nil
+}
+
+// Handler6 handles DHCPv6 packets for the dns plugin
+func Handler6(req, resp dhcpv6.DHCPv6) (dhcpv6.DHCPv6, bool) {
+	decap, err := req.GetInnerMessage()
+	if err != nil {
+		log.Errorf("Could not decapsulate relayed message, aborting: %v", err)
+		return nil, true
+	}
+
+	if decap.IsOptionRequested(dhcpv6.OptionDNSRecursiveNameServer) {
+		resp.UpdateOption(dhcpv6.OptDNS(dnsServers6...))
+	}
+	return resp, false
+}
+
+//Handler4 handles DHCPv4 packets for the dns plugin
+func Handler4(req, resp *dhcpv4.DHCPv4) (*dhcpv4.DHCPv4, bool) {
+	if req.IsOptionRequested(dhcpv4.OptionDomainNameServer) {
+		resp.Options.Update(dhcpv4.OptDNS(dnsServers4...))
+	}
+	return resp, false
+}