122 lines
2.8 KiB
Go
122 lines
2.8 KiB
Go
// Copyright 2018 Google Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Binary dnsd answers DNS requests by forwarding or consulting DHCP leases.
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package main
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import (
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"encoding/json"
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"flag"
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"io/ioutil"
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"log"
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"net"
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"net/http"
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"os"
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"os/signal"
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"syscall"
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"github.com/gokrazy/gokrazy"
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miekgdns "github.com/miekg/dns"
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"router7/internal/dhcp4d"
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"router7/internal/dns"
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"router7/internal/multilisten"
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"router7/internal/netconfig"
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_ "net/http/pprof"
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)
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var (
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httpListeners = multilisten.NewPool()
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dnsListeners = multilisten.NewPool()
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)
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func updateListeners(mux *miekgdns.ServeMux) error {
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hosts, err := gokrazy.PrivateInterfaceAddrs()
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if err != nil {
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return err
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}
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dnsListeners.ListenAndServe(hosts, func(host string) multilisten.Listener {
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return &listenerAdapter{&miekgdns.Server{
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Addr: net.JoinHostPort(host, "53"),
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Net: "udp",
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Handler: mux,
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}}
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})
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if net1, err := multilisten.IPv6Net1("/perm"); err == nil {
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hosts = append(hosts, net1)
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}
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httpListeners.ListenAndServe(hosts, func(host string) multilisten.Listener {
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return &http.Server{Addr: net.JoinHostPort(host, "8053")}
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})
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return nil
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}
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type listenerAdapter struct {
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*miekgdns.Server
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}
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func (a *listenerAdapter) Close() error { return a.Shutdown() }
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func logic() error {
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// TODO: set correct upstream DNS resolver(s)
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ip, err := netconfig.LinkAddress("/perm", "lan0")
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if err != nil {
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return err
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}
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srv := dns.NewServer(ip.String()+":53", "lan")
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readLeases := func() error {
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b, err := ioutil.ReadFile("/perm/dhcp4d/leases.json")
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if err != nil {
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return err
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}
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var leases []dhcp4d.Lease
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if err := json.Unmarshal(b, &leases); err != nil {
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return err
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}
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srv.SetLeases(leases)
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return nil
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}
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if err := readLeases(); err != nil {
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log.Printf("cannot resolve DHCP hostnames: %v", err)
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}
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http.Handle("/metrics", srv.PrometheusHandler())
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if err := updateListeners(srv.Mux); err != nil {
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return err
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}
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ch := make(chan os.Signal, 1)
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signal.Notify(ch, syscall.SIGUSR1)
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for range ch {
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if err := updateListeners(srv.Mux); err != nil {
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log.Printf("updateListeners: %v", err)
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}
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if err := readLeases(); err != nil {
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log.Printf("readLeases: %v", err)
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}
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}
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return nil
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}
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func main() {
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// TODO: drop privileges, run as separate uid?
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flag.Parse()
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if err := logic(); err != nil {
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log.Fatal(err)
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}
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}
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