forked from libp2p/go-libp2p
-
Notifications
You must be signed in to change notification settings - Fork 0
/
mdns.go
204 lines (173 loc) · 3.89 KB
/
mdns.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
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
package discovery
import (
"context"
"errors"
"io"
"io/ioutil"
golog "log"
"net"
"sync"
"time"
logging "github.com/ipfs/go-log"
"github.com/libp2p/go-libp2p-host"
"github.com/libp2p/go-libp2p-peer"
pstore "github.com/libp2p/go-libp2p-peerstore"
ma "github.com/multiformats/go-multiaddr"
manet "github.com/multiformats/go-multiaddr-net"
"github.com/whyrusleeping/mdns"
)
var log = logging.Logger("mdns")
const ServiceTag = "_ipfs-discovery._udp"
type Service interface {
io.Closer
RegisterNotifee(Notifee)
UnregisterNotifee(Notifee)
}
type Notifee interface {
HandlePeerFound(pstore.PeerInfo)
}
type mdnsService struct {
server *mdns.Server
service *mdns.MDNSService
host host.Host
tag string
lk sync.Mutex
notifees []Notifee
interval time.Duration
}
func getDialableListenAddrs(ph host.Host) ([]*net.TCPAddr, error) {
var out []*net.TCPAddr
for _, addr := range ph.Addrs() {
na, err := manet.ToNetAddr(addr)
if err != nil {
continue
}
tcp, ok := na.(*net.TCPAddr)
if ok {
out = append(out, tcp)
}
}
if len(out) == 0 {
return nil, errors.New("failed to find good external addr from peerhost")
}
return out, nil
}
func NewMdnsService(ctx context.Context, peerhost host.Host, interval time.Duration, serviceTag string) (Service, error) {
// TODO: dont let mdns use logging...
golog.SetOutput(ioutil.Discard)
var ipaddrs []net.IP
port := 4001
addrs, err := getDialableListenAddrs(peerhost)
if err != nil {
log.Warning(err)
} else {
port = addrs[0].Port
for _, a := range addrs {
ipaddrs = append(ipaddrs, a.IP)
}
}
myid := peerhost.ID().Pretty()
info := []string{myid}
if serviceTag == "" {
serviceTag = ServiceTag
}
service, err := mdns.NewMDNSService(myid, serviceTag, "", "", port, ipaddrs, info)
if err != nil {
return nil, err
}
// Create the mDNS server, defer shutdown
server, err := mdns.NewServer(&mdns.Config{Zone: service})
if err != nil {
return nil, err
}
s := &mdnsService{
server: server,
service: service,
host: peerhost,
interval: interval,
tag: serviceTag,
}
go s.pollForEntries(ctx)
return s, nil
}
func (m *mdnsService) Close() error {
return m.server.Shutdown()
}
func (m *mdnsService) pollForEntries(ctx context.Context) {
ticker := time.NewTicker(m.interval)
for {
select {
case <-ticker.C:
entriesCh := make(chan *mdns.ServiceEntry, 16)
go func() {
for entry := range entriesCh {
m.handleEntry(entry)
}
}()
log.Debug("starting mdns query")
qp := &mdns.QueryParam{
Domain: "local",
Entries: entriesCh,
Service: m.tag,
Timeout: time.Second * 5,
}
err := mdns.Query(qp)
if err != nil {
log.Error("mdns lookup error: ", err)
}
close(entriesCh)
log.Debug("mdns query complete")
case <-ctx.Done():
log.Debug("mdns service halting")
return
}
}
}
func (m *mdnsService) handleEntry(e *mdns.ServiceEntry) {
log.Debugf("Handling MDNS entry: %s:%d %s", e.AddrV4, e.Port, e.Info)
mpeer, err := peer.IDB58Decode(e.Info)
if err != nil {
log.Warning("Error parsing peer ID from mdns entry: ", err)
return
}
if mpeer == m.host.ID() {
log.Debug("got our own mdns entry, skipping")
return
}
maddr, err := manet.FromNetAddr(&net.TCPAddr{
IP: e.AddrV4,
Port: e.Port,
})
if err != nil {
log.Warning("Error parsing multiaddr from mdns entry: ", err)
return
}
pi := pstore.PeerInfo{
ID: mpeer,
Addrs: []ma.Multiaddr{maddr},
}
m.lk.Lock()
for _, n := range m.notifees {
go n.HandlePeerFound(pi)
}
m.lk.Unlock()
}
func (m *mdnsService) RegisterNotifee(n Notifee) {
m.lk.Lock()
m.notifees = append(m.notifees, n)
m.lk.Unlock()
}
func (m *mdnsService) UnregisterNotifee(n Notifee) {
m.lk.Lock()
found := -1
for i, notif := range m.notifees {
if notif == n {
found = i
break
}
}
if found != -1 {
m.notifees = append(m.notifees[:found], m.notifees[found+1:]...)
}
m.lk.Unlock()
}