peerdiscovery

README

peerdiscovery

Pure-go library for cross-platform thread-safe local peer discovery using UDP multicast. I needed to use peer discovery for croc and everything I tried had problems, so I made another one.

Install

Make sure you have Go 1.5+.

go get -u github.com/schollz/peerdiscovery

Usage

The following is a code to find the first peer on the local network and print it out.

discoveries, _ := peerdiscovery.Discover(peerdiscovery.Settings{Limit: 1})
for _, d := range discoveries {
    fmt.Printf("discovered '%s'\n", d.Address)
}

Here's the output when running on two computers. (Run these gifs in sync by hitting Ctl + F5).

Computer 1:

Computer 2:

For more examples, see the scanning example or the docs.

Contributing

Pull requests are welcome. Feel free to...

• Revise documentation
• Add new features
• Fix bugs
• Suggest improvements

License

MIT

Documentation

Index

• type Discovered
  • func Discover(settings ...Settings) (discoveries []Discovered, err error)
• type Settings

Types

type Discovered

type Discovered struct {
	// Address is the local address of a discovered peer.
	Address string
	// Payload is the associated payload from discovered peer.
	Payload []byte
}

Discovered is the structure of the discovered peers, which holds their local address (port removed) and a payload if there is one.

func Discover

func Discover(settings ...Settings) (discoveries []Discovered, err error)

Discover will use the created settings to scan for LAN peers. It will return an array of the discovered peers and their associate payloads. It will not return broadcasts sent to itself.

type Settings

type Settings struct {
	// Limit is the number of peers to discover, use < 1 for unlimited.
	Limit int
	// Port is the port to broadcast on (the peers must also broadcast using the same port).
	// The default port is 9999.
	Port string
	// MulticastAddress specifies the multicast address.
	// You should be able to use any between 224.0.0.0 to 239.255.255.255.
	// By default it uses the Simple Service Discovery Protocol
	// address (239.255.255.250).
	MulticastAddress string
	// Payload is the bytes that are sent out with each broadcast. Must be short.
	Payload []byte
	// Delay is the amount of time between broadcasts. The default delay is 1 second.
	Delay time.Duration
	// TimeLimit is the amount of time to spend discovering, if the limit is not reached.
	// The default time limit is 10 seconds.
	TimeLimit time.Duration
	// AllowSelf will allow discovery the local machine (default false)
	AllowSelf bool
	// contains filtered or unexported fields
}

Settings are the settings that can be specified for doing peer discovery.