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discovery.go
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discovery.go
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package dns
import (
"context"
"errors"
"fmt"
"github.com/ethereum/go-ethereum/p2p/dnsdisc"
"github.com/libp2p/go-libp2p-core/discovery"
"github.com/libp2p/go-libp2p-core/peer"
"github.com/multiformats/go-multiaddr"
)
type Resolver interface {
LookupTXT(ctx context.Context, name string) ([]string, error)
}
type dnsDiscovery struct {
domain string
r Resolver
c dnsdisc.Client
}
func NewDNSDiscovery(domain string, r Resolver, c dnsdisc.Client) discovery.Discoverer {
return &dnsDiscovery{
domain: domain,
r: r,
c: c,
}
}
func (d *dnsDiscovery) FindPeers(ctx context.Context, ns string, opts ...discovery.Option) (<-chan peer.AddrInfo, error) {
// Get options
var options discovery.Options
err := options.Apply(opts...)
if err != nil {
return nil, err
}
c := make(chan peer.AddrInfo)
tree, err := d.c.SyncTree(d.domain)
if err != nil {
return nil, err
}
if tree == nil {
return nil, errors.New("empty tree returned")
}
nodes := tree.Nodes()
limit := options.Limit
// @todo move this into another function, more libp2p like.
go func() {
for i, n := range nodes {
if limit >= i {
break
}
addr, err := multiaddr.NewMultiaddr(fmt.Sprintf("/ip4/%s/tcp/%d/udp/%d", n.IP(), n.TCP(), n.UDP()))
if err != nil {
continue
}
p, err := peer.AddrInfoFromP2pAddr(addr)
if err != nil {
continue
}
c <- *p
}
}()
return c, nil
}