DNS-SD

This library implements Multicast DNS and DNS-Based Service Discovery to provide zero-configuration operations. It lets you announce and find services in a specific link-local domain.

Usage

Create a mDNS responder

The following code creates a service with name "My Website._http._tcp.local." for the host "My Computer" which has the IP "192.168.0.123" on port "12345". The service is added to a responder.

import (
	"context"
	"github.com/brutella/dnssd"
)

cfg := dnssd.Config{
    Name:   "My Website",
    Type:   "_http._tcp",
    Domain: "local",
    Host:   "My Computer",
    IPs:    []net.IP{net.ParseIP("192.168.0.123")},
    Port:   12345,
}
sv, _ := dnssd.NewService(cfg)

In most cases you only need to specify the name, type and port of the service.

cfg := dnssd.Config{
    Name:   "My Website",
    Type:   "_http._tcp",
    Port:   12345,
}
sv, _ := dnssd.NewService(cfg)

Then you create a responder and add the service to it.

rp, _ := dnssd.NewResponder()
hdl, _ := rp.Add(sv)

ctx, cancel := context.WithCancel(context.Background())
defer cancel()

rp.Respond(ctx)

When calling Respond the responder probes for the service instance name and host name to be unqiue in the network. Once probing is finished, the service will be announced.

Update TXT records

Once a service is added to a responder, you can use the hdl to update properties.

hdl.UpdateText(map[string]string{"key1": "value1", "key2": "value2"}, rsp)

Examples

There are examples in the _cmd directory to register services, resolve service instances and to browse for service types.

Conformance

This library passes the multicast DNS tests of Apple's Bonjour Conformance Test.

TODO

• Support hot plugging
• Support negative responses (RFC6762 6.1)
• Handle txt records case insensitive
• Remove outdated services from cache regularly
• Make sure that hostnames are FQDNs

Contact

Matthias Hochgatterer

Github: https://github.com/brutella

Twitter: https://twitter.com/brutella

License

dnssd is available under the MIT license. See the LICENSE file for more info.