mdns

Documentation

Overview

Package `mdns` implements a multicast DNS client and server to be used to discover and register services over local networks

Index

• Constants
• func NewWithPlugin(p Plugin, label string) (*mdns, error)
• type EventType
  • func (t EventType) String() string
• type Message
  • func MessageFromPacket(packet []byte, sender net.Addr, iface net.Interface) (Message, error)
  • func NewBrowseQuestion(question string, iface net.Interface) (Message, error)
  • func NewDiscoverQuestion(question string, iface net.Interface) (Message, error)
  • func NewLookupQuestion(question string, iface net.Interface) (Message, error)
• type Plugin
  • func WithLabel(label string) Plugin
  • func (p Plugin) Domain() string
  • func (p Plugin) Interfaces() ([]net.Interface, error)
  • func (p Plugin) Label() string
  • func (p Plugin) Name() string
  • func (p Plugin) New(parent context.Context, _ iface.Provider) (iface.Task, error)
• type Ptr
• type Registration
• type RespInstances
• type RespServices
• type Service
• type Services
  • func (srv *Services) AddA(key string, r []net.IP)
  • func (srv *Services) AddPTR(key, service string, ptr Ptr, ifindex int) bool
  • func (srv *Services) AddSRV(key string, r []Srv)
  • func (srv *Services) AddTXT(key string, txt []string)
  • func (srv *Services) ExpireInstances() []*Service
  • func (srv *Services) Expired(key string) bool
  • func (srv *Services) GetInstances(services ...string) []*Service
  • func (srv *Services) GetNames() []string
  • func (srv *Services) NextBrowseName(ttl time.Duration) string
  • func (srv *Services) NextLookupInstance() *Service
  • func (srv *Services) Registered(name string, ttl time.Duration) bool
• type Srv

Constants

const (
	DefaultName  = "mdns"  // Name of the plugin
	DefaultLabel = "local" // Default domain label and zone

)

const (
	ScopeRead  = "github.com/mutablelogic/go-server/mdns:read"
	ScopeWrite = "github.com/mutablelogic/go-server/mdns:write"
)

Functions

func NewWithPlugin

func NewWithPlugin(p Plugin, label string) (*mdns, error)

Create a new logger task with provider of other tasks

Types

type EventType

type EventType uint

const (
	None EventType = iota
	Question
	Answer
	Registered
	Resolved
	Expired
	Sent
)

func (EventType) String

func (t EventType) String() string

type Message

type Message interface {
	PTR() []Ptr              // Return PTR records
	A() []net.IP             // Return A and AAAA records
	TXT() (string, []string) // Return TXT records
	SRV() (string, []Srv)    // Return SRV records
	Bytes() ([]byte, error)  // Return the packed message
	IsAnswer() bool          // Return true when the message is an answer
	IfIndex() int            // Interface to send and receive on, or nil
}

A sent or received message

func MessageFromPacket

func MessageFromPacket(packet []byte, sender net.Addr, iface net.Interface) (Message, error)

Create a message from a received packet, with a sender and the interface that the message was received on

func NewBrowseQuestion

func NewBrowseQuestion(question string, iface net.Interface) (Message, error)

Create a message from a question, to be sent on a specific interface or on all interfaces if the index is zero

func NewDiscoverQuestion

func NewDiscoverQuestion(question string, iface net.Interface) (Message, error)

Create a message from a question, to be sent on a specific interface or on all interfaces if the index is zero

func NewLookupQuestion

func NewLookupQuestion(question string, iface net.Interface) (Message, error)

Create a message from a question to retrieve TXT and SRV records, to be sent on a specific interface or on all interfaces if the index is zero

type Plugin

type Plugin struct {
	task.Plugin
	Interface string `json:"interface,omitempty"`
	Domain_   string `json:"domain,omitempty"`
}

func WithLabel

func WithLabel(label string) Plugin

func (Plugin) Domain

func (p Plugin) Domain() string

func (Plugin) Interfaces

func (p Plugin) Interfaces() ([]net.Interface, error)

func (Plugin) Label

func (p Plugin) Label() string

func (Plugin) Name

func (p Plugin) Name() string

func (Plugin) New

func (p Plugin) New(parent context.Context, _ iface.Provider) (iface.Task, error)

Create a new logger task with provider of other tasks

type Ptr

type Ptr interface {
	Service() string    // Return service
	Name() string       // Return name
	TTL() time.Duration // Return time-to-live for record
}

type Registration

type Registration struct {
	Browsed time.Time
	Expires time.Time
}

type RespInstances

type RespInstances struct {
	Zone      string     `json:"zone,omitempty"`
	Service   string     `json:"service,omitempty"`
	Instances []*Service `json:"instances,omitempty"`
}

type RespServices

type RespServices struct {
	Zone     string   `json:"zone,omitempty"`
	Services []string `json:"services,omitempty"`
}

type Service

type Service struct {
	Name    string            `json:"name,omitempty"`
	Service string            `json:"service,omitempty"`
	Added   time.Time         `json:"added,omitempty"`
	Expires time.Time         `json:"expires,omitempty"`
	A       []net.IP          `json:"a,omitempty"`
	SRV     []Srv             `json:"srv,omitempty"`
	TXT     map[string]string `json:"txt,omitempty"`
	IfIndex int               `json:"-"`
}

type Services

type Services struct {
	sync.RWMutex
	// contains filtered or unexported fields
}

Services stores the service names and registrations

func (*Services) AddA

func (srv *Services) AddA(key string, r []net.IP)

AddAddr to instance

func (*Services) AddPTR

func (srv *Services) AddPTR(key, service string, ptr Ptr, ifindex int) bool

AddPTR from service name to record, with a TTL, and return true if the service was registered rather than updated

func (*Services) AddSRV

func (srv *Services) AddSRV(key string, r []Srv)

AddSRV to instance

func (*Services) AddTXT

func (srv *Services) AddTXT(key string, txt []string)

AddTXT to instance

func (*Services) ExpireInstances

func (srv *Services) ExpireInstances() []*Service

Expire service instances and return them

func (*Services) Expired

func (srv *Services) Expired(key string) bool

Expire a service instance and return true if the service was deleted

func (*Services) GetInstances

func (srv *Services) GetInstances(services ...string) []*Service

Get the list of service instances which have not expired.

func (*Services) GetNames

func (srv *Services) GetNames() []string

Get the list of service names which have not expired.

func (*Services) NextBrowseName

func (srv *Services) NextBrowseName(ttl time.Duration) string

Returns a service name which should be browsed for instances. Will return an empty string if no service names are available, or if browsing has occurred within the ttl period.

func (*Services) NextLookupInstance

func (srv *Services) NextLookupInstance() *Service

Returns an instance name which should be looked up. Will return an empty string if no instances are available

func (*Services) Registered

func (srv *Services) Registered(name string, ttl time.Duration) bool

Register a service name to the list of services, with a TTL and return true if the service was registered rather than updated

type Srv

type Srv interface {
	Host() string     // Return host
	Port() uint16     // Return port
	Priority() uint16 // Return priority
}