discover

Documentation

Overview

Package discover implements the Node Discovery Protocol.

The Node Discovery protocol provides a way to find RLPx nodes that can be connected to. It uses a Kademlia-like protocol to maintain a distributed database of the IDs and endpoints of all listening nodes.

Index

• type Config
• type ReadPacket
• type Table
  • func (tab *Table) ReadRandomNodes(buf []*enode.Node) (n int)
• type UDPConn
• type UDPv5
  • func ListenV5(conn UDPConn, ln *enode.LocalNode, cfg Config) (*UDPv5, error)
  • func (t *UDPv5) AddRecentNode(n *enode.Node, at time.Time, liveness uint)
  • func (t *UDPv5) AllNodes() []*enode.Node
  • func (t *UDPv5) Close()
  • func (t *UDPv5) LocalNode() *enode.LocalNode
  • func (t *UDPv5) Lookup(target enode.ID) []*enode.Node
  • func (t *UDPv5) Ping(n *enode.Node) error
  • func (t *UDPv5) PingSeq(n *enode.Node) (uint64, error)
  • func (t *UDPv5) RandomNodes() enode.Iterator
  • func (t *UDPv5) RegisterTalkHandler(protocol string, handler func([]byte) []byte)
  • func (t *UDPv5) RequestENR(n *enode.Node) (*enode.Node, error)
  • func (t *UDPv5) Resolve(n *enode.Node) *enode.Node
  • func (t *UDPv5) SeeNode(n *enode.Node, at time.Time, liveness uint)
  • func (t *UDPv5) Self() *enode.Node
  • func (t *UDPv5) TalkRequest(n *enode.Node, protocol string, request []byte) ([]byte, error)

Types

type Config

type Config struct {
	// These settings are required and configure the UDP listener:
	PrivateKey *ecdsa.PrivateKey

	// CATDOG HACK
	Revalidator func(node2 *enode.Node) (uint64, error)
	OnSeen      func(n *enode.Node, at time.Time, liveness uint)

	// These settings are optional:
	NetRestrict  *netutil.Netlist   // network whitelist
	Bootnodes    []*enode.Node      // list of bootstrap nodes
	Unhandled    chan<- ReadPacket  // unhandled packets are sent on this channel
	Log          log.Logger         // if set, log messages go here
	ValidSchemes enr.IdentityScheme // allowed identity schemes
	Clock        mclock.Clock
}

Config holds settings for the discovery listener.

type ReadPacket

type ReadPacket struct {
	Data []byte
	Addr *net.UDPAddr
}

ReadPacket is a packet that couldn't be handled. Those packets are sent to the unhandled channel if configured.

type Table

type Table struct {
	// contains filtered or unexported fields
}

Table is the 'node table', a Kademlia-like index of neighbor nodes. The table keeps itself up-to-date by verifying the liveness of neighbors and requesting their node records when announcements of a new record version are received.

func (*Table) ReadRandomNodes

func (tab *Table) ReadRandomNodes(buf []*enode.Node) (n int)

ReadRandomNodes fills the given slice with random nodes from the table. The results are guaranteed to be unique for a single invocation, no node will appear twice.

type UDPConn

type UDPConn interface {
	ReadFromUDP(b []byte) (n int, addr *net.UDPAddr, err error)
	WriteToUDP(b []byte, addr *net.UDPAddr) (n int, err error)
	Close() error
	LocalAddr() net.Addr
}

UDPConn is a network connection on which discovery can operate.

type UDPv5

type UDPv5 struct {
	// contains filtered or unexported fields
}

UDPv5 is the implementation of protocol version 5.

func ListenV5

func ListenV5(conn UDPConn, ln *enode.LocalNode, cfg Config) (*UDPv5, error)

ListenV5 listens on the given connection.

func (*UDPv5) AddRecentNode

func (t *UDPv5) AddRecentNode(n *enode.Node, at time.Time, liveness uint)

func (*UDPv5) AllNodes

func (t *UDPv5) AllNodes() []*enode.Node

AllNodes returns all the nodes stored in the local table.

func (*UDPv5) Close

func (t *UDPv5) Close()

Close shuts down packet processing.

func (*UDPv5) LocalNode

func (t *UDPv5) LocalNode() *enode.LocalNode

LocalNode returns the current local node running the protocol.

func (*UDPv5) Lookup

func (t *UDPv5) Lookup(target enode.ID) []*enode.Node

Lookup performs a recursive lookup for the given target. It returns the closest nodes to target.

func (*UDPv5) Ping

func (t *UDPv5) Ping(n *enode.Node) error

Ping sends a ping message to the given node.

func (*UDPv5) PingSeq

func (t *UDPv5) PingSeq(n *enode.Node) (uint64, error)

PingSeq sends a ping message to the given node.

func (*UDPv5) RandomNodes

func (t *UDPv5) RandomNodes() enode.Iterator

RandomNodes returns an iterator that finds random nodes in the DHT.

func (*UDPv5) RegisterTalkHandler

func (t *UDPv5) RegisterTalkHandler(protocol string, handler func([]byte) []byte)

RegisterTalkHandler adds a handler for 'talk requests'. The handler function is called whenever a request for the given protocol is received and should return the response data or nil.

func (*UDPv5) RequestENR

func (t *UDPv5) RequestENR(n *enode.Node) (*enode.Node, error)

requestENR requests n's record.

func (*UDPv5) Resolve

func (t *UDPv5) Resolve(n *enode.Node) *enode.Node

Resolve searches for a specific node with the given ID and tries to get the most recent version of the node record for it. It returns n if the node could not be resolved.

func (*UDPv5) SeeNode

func (t *UDPv5) SeeNode(n *enode.Node, at time.Time, liveness uint)

func (*UDPv5) Self

func (t *UDPv5) Self() *enode.Node

Self returns the local node record.

func (*UDPv5) TalkRequest

func (t *UDPv5) TalkRequest(n *enode.Node, protocol string, request []byte) ([]byte, error)

TalkRequest sends a talk request to n and waits for a response.