/
sd.go
135 lines (123 loc) · 2.68 KB
/
sd.go
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package internal
import (
"context"
"fmt"
"net"
"runtime"
"strconv"
"sync"
"time"
"github.com/brutella/dnssd"
"golang.org/x/sync/errgroup"
)
type ServiceDiscovery struct {
service dnssd.Service
responder dnssd.Responder
mu *sync.Mutex
peers map[string]string
onPeersUpdate func([]string)
}
func NewServiceDiscovery(port int, onPeersUpdate func([]string)) (ServiceDiscovery, error) {
config := dnssd.Config{
Name: fmt.Sprintf("%s-%s", "clipsync", runtime.GOOS),
Type: "_clipsync._tcp",
Port: port,
Domain: "local",
}
service, err := dnssd.NewService(config)
if err != nil {
return ServiceDiscovery{}, err
}
responder, err := dnssd.NewResponder()
if err != nil {
return ServiceDiscovery{}, err
}
return ServiceDiscovery{
service: service,
responder: responder,
mu: new(sync.Mutex),
peers: make(map[string]string, 4),
onPeersUpdate: onPeersUpdate,
}, nil
}
func (sd *ServiceDiscovery) peerList() []string {
peerList := make([]string, 0, len(sd.peers))
for k := range sd.peers {
peerList = append(peerList, k)
}
return peerList
}
func (sd *ServiceDiscovery) browse(ctx context.Context) error {
err := dnssd.LookupType(
ctx,
"_clipsync._tcp.local.",
func(be dnssd.BrowseEntry) {
sd.mu.Lock()
defer sd.mu.Unlock()
if be.Name == sd.service.Name {
return
}
for _, peerIP := range be.IPs {
if !peerIP.IsPrivate() {
continue
}
if peerIP.To4() == nil {
continue
}
ip := peerIP.String()
port := strconv.Itoa(be.Port)
addr := net.JoinHostPort(ip, port)
sd.peers[addr] = be.Name
}
peerList := sd.peerList()
go sd.onPeersUpdate(peerList)
},
func(be dnssd.BrowseEntry) {
sd.mu.Lock()
defer sd.mu.Unlock()
for _, peerIP := range be.IPs {
ip := peerIP.String()
port := strconv.Itoa(be.Port)
addr := net.JoinHostPort(ip, port)
delete(sd.peers, addr)
}
peerList := sd.peerList()
go sd.onPeersUpdate(peerList)
})
if err != nil && ctx.Err() == nil {
return err
}
return nil
}
func (sd *ServiceDiscovery) Run(ctx context.Context) error {
ctx, cancel := context.WithCancel(ctx)
defer cancel()
errgrp := new(errgroup.Group)
errgrp.Go(func() error {
defer cancel()
handle, err := sd.responder.Add(sd.service)
if err != nil {
return err
}
defer sd.responder.Remove(handle)
err = sd.responder.Respond(ctx)
if err != nil && ctx.Err() == nil {
return err
}
return nil
})
errgrp.Go(func() error {
defer cancel()
for {
select {
case <-ctx.Done():
return nil
case <-time.After(time.Second):
if err := sd.browse(ctx); err != nil {
return err
}
}
}
})
return errgrp.Wait()
}