go-emlid/reach/discovery/discovery.go

81 lines
1.4 KiB
Go

package discovery
import (
"context"
"log"
"net"
"github.com/grandcat/zeroconf"
"github.com/pkg/errors"
"github.com/wlynxg/anet"
)
// Service is a ReachRS service discovered via MDNS-SD
type Service struct {
Name string
AddrV4 *net.IP
Port int
}
// Discover tries to discover ReachRS services on the local network via mDNS-SD
func Discover(ctx context.Context) ([]Service, error) {
services := make([]Service, 0)
watch, err := Watch(ctx)
if err != nil {
return nil, errors.WithStack(err)
}
for srv := range watch {
services = append(services, srv)
}
return services, nil
}
// Watch watches ReachRS services on the local network via mDNS-SD
func Watch(ctx context.Context) (chan Service, error) {
ifaces, err := anet.Interfaces()
if err != nil {
return nil, errors.WithStack(err)
}
log.Printf("%v", ifaces)
out := make(chan Service, 0)
resolver, err := zeroconf.NewResolver(
zeroconf.SelectIfaces(ifaces),
zeroconf.SelectIPTraffic(zeroconf.IPv4),
)
if err != nil {
return nil, errors.WithStack(err)
}
entries := make(chan *zeroconf.ServiceEntry)
go func() {
defer close(out)
for e := range entries {
var addr *net.IP
if len(e.AddrIPv4) > 0 {
addr = &e.AddrIPv4[0]
}
srv := Service{
Name: e.Instance,
AddrV4: addr,
Port: e.Port,
}
out <- srv
}
}()
if err = resolver.Browse(ctx, "_reach._tcp", ".local", entries); err != nil {
return nil, err
}
return out, nil
}