status-im/status-go

package discovery

import (
    "crypto/ecdsa"
    "net"
    "sync"
    "time"

    "github.com/ethereum/go-ethereum/log"
    "github.com/ethereum/go-ethereum/p2p/discv5"
)

// NewDiscV5 creates instances of discovery v5 facade.
func NewDiscV5(prv *ecdsa.PrivateKey, laddr string, bootnodes []*discv5.Node) *DiscV5 {
    return &DiscV5{
        prv:       prv,
        laddr:     laddr,
        bootnodes: bootnodes,
    }
}

// DiscV5 is a facade for ethereum discv5 implementation.
type DiscV5 struct {
    mu  sync.Mutex
    net *discv5.Network

    prv       *ecdsa.PrivateKey
    laddr     string
    bootnodes []*discv5.Node
}

// Running returns true if v5 server is started.
func (d *DiscV5) Running() bool {
    d.mu.Lock()
    defer d.mu.Unlock()
    return d.net != nil
}

// Start creates v5 server and stores pointer to it.
func (d *DiscV5) Start() error {
    d.mu.Lock()
    defer d.mu.Unlock()
    log.Debug("Starting discovery", "listen address", d.laddr)
    addr, err := net.ResolveUDPAddr("udp", d.laddr)
    if err != nil {
        return err
    }
    conn, err := net.ListenUDP("udp", addr)
    if err != nil {
        return err
    }
    ntab, err := discv5.ListenUDP(d.prv, conn, "", nil)
    if err != nil {
        return err
    }
    if err := ntab.SetFallbackNodes(d.bootnodes); err != nil {
        return err
    }
    d.net = ntab
    return nil
}

// Stop closes v5 server listener and removes pointer.
func (d *DiscV5) Stop() error {
    d.mu.Lock()
    defer d.mu.Unlock()
    if d.net == nil {
        return nil
    }
    d.net.Close()
    d.net = nil
    return nil
}

// Register creates a register request in v5 server.
// It will block until stop is closed.
func (d *DiscV5) Register(topic string, stop chan struct{}) error {
    d.net.RegisterTopic(discv5.Topic(topic), stop)
    return nil
}

// Discover creates search request in v5 server. Results will be published to found channel.
// It will block until period is closed.
func (d *DiscV5) Discover(topic string, period <-chan time.Duration, found chan<- *discv5.Node, lookup chan<- bool) error {
    d.net.SearchTopic(discv5.Topic(topic), period, found, lookup)
    return nil
}