-
Notifications
You must be signed in to change notification settings - Fork 109
/
dnsd.go
131 lines (115 loc) · 3.2 KB
/
dnsd.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
// Copyright 2018 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Binary dnsd answers DNS requests by forwarding or consulting DHCP leases.
package main
import (
"encoding/json"
"flag"
"io/ioutil"
"log"
"net"
"net/http"
"os"
"os/signal"
"syscall"
"github.com/gokrazy/gokrazy"
miekgdns "github.com/miekg/dns"
"github.com/rtr7/router7/internal/dhcp4d"
"github.com/rtr7/router7/internal/dns"
"github.com/rtr7/router7/internal/multilisten"
"github.com/rtr7/router7/internal/netconfig"
_ "net/http/pprof"
)
var (
httpListeners = multilisten.NewPool()
dnsUDPListeners = multilisten.NewPool()
dnsTCPListeners = multilisten.NewPool()
)
func updateListeners(mux *miekgdns.ServeMux) error {
privateAddrs, err := gokrazy.PrivateInterfaceAddrs()
if err != nil {
return err
}
dnsUDPListeners.ListenAndServe(privateAddrs, func(host string) multilisten.Listener {
return &listenerAdapter{&miekgdns.Server{
Addr: net.JoinHostPort(host, "53"),
Net: "udp",
Handler: mux,
}}
})
dnsTCPListeners.ListenAndServe(privateAddrs, func(host string) multilisten.Listener {
return &listenerAdapter{&miekgdns.Server{
Addr: net.JoinHostPort(host, "53"),
Net: "tcp",
Handler: mux,
}}
})
if net1, err := multilisten.IPv6Net1("/perm"); err == nil {
privateAddrs = append(privateAddrs, net1)
}
httpListeners.ListenAndServe(privateAddrs, func(host string) multilisten.Listener {
return &http.Server{Addr: net.JoinHostPort(host, "8053")}
})
return nil
}
type listenerAdapter struct {
*miekgdns.Server
}
func (a *listenerAdapter) Close() error { return a.Shutdown() }
func logic() error {
// TODO: set correct upstream DNS resolver(s)
ip, err := netconfig.LinkAddress("/perm", "lan0")
if err != nil {
return err
}
srv := dns.NewServer(ip.String()+":53", "lan")
readLeases := func() error {
b, err := ioutil.ReadFile("/perm/dhcp4d/leases.json")
if err != nil {
return err
}
var leases []dhcp4d.Lease
if err := json.Unmarshal(b, &leases); err != nil {
return err
}
srv.SetLeases(leases)
return nil
}
if err := readLeases(); err != nil {
log.Printf("cannot resolve DHCP hostnames: %v", err)
}
http.Handle("/metrics", srv.PrometheusHandler())
http.HandleFunc("/dyndns", srv.DyndnsHandler)
if err := updateListeners(srv.Mux); err != nil {
return err
}
ch := make(chan os.Signal, 1)
signal.Notify(ch, syscall.SIGUSR1)
for range ch {
if err := updateListeners(srv.Mux); err != nil {
log.Printf("updateListeners: %v", err)
}
if err := readLeases(); err != nil {
log.Printf("readLeases: %v", err)
}
}
return nil
}
func main() {
// TODO: drop privileges, run as separate uid?
flag.Parse()
if err := logic(); err != nil {
log.Fatal(err)
}
}