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discovery.go
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discovery.go
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// Copyright 2019 The CortexTheseus Authors
// This file is part of the CortexTheseus library.
//
// The CortexTheseus library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The CortexTheseus library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the CortexTheseus library. If not, see <http://www.gnu.org/licenses/>.
package ctxc
import (
"github.com/CortexFoundation/CortexTheseus/core"
"github.com/CortexFoundation/CortexTheseus/core/forkid"
"github.com/CortexFoundation/CortexTheseus/log"
"github.com/CortexFoundation/CortexTheseus/p2p/dnsdisc"
"github.com/CortexFoundation/CortexTheseus/p2p/enode"
"github.com/CortexFoundation/CortexTheseus/rlp"
)
// ctxcEntry is the "ctxc" ENR entry which advertises ctxc protocol
// on the discovery network.
type ctxcEntry struct {
ForkID forkid.ID // Fork identifier per EIP-2124
// Ignore additional fields (for forward compatibility).
Rest []rlp.RawValue `rlp:"tail"`
}
// ENRKey implements enr.Entry.
func (e ctxcEntry) ENRKey() string {
return "ctxc"
}
// startCtxcEntryUpdate starts the ENR updater loop.
func (ctxc *Cortex) startCtxcEntryUpdate(ln *enode.LocalNode) {
var newHead = make(chan core.ChainHeadEvent, 10)
sub := ctxc.blockchain.SubscribeChainHeadEvent(newHead)
go func() {
defer sub.Unsubscribe()
for {
select {
case <-newHead:
ln.Set(ctxc.currentCtxcEntry())
case err := <-sub.Err():
// Would be nice to sync with ctxc.Stop, but there is no
// good way to do that.
log.Warn("Local dns discovery quit", "err", err)
return
}
}
}()
}
func (ctxc *Cortex) currentCtxcEntry() *ctxcEntry {
return &ctxcEntry{ForkID: forkid.NewID(ctxc.blockchain.Config(), ctxc.blockchain.Genesis().Hash(),
ctxc.blockchain.CurrentHeader().Number.Uint64())}
}
// setupDiscovery creates the node discovery source for the ctxc protocol.
func (ctxc *Cortex) setupDiscovery() (enode.Iterator, error) {
if len(ctxc.config.DiscoveryURLs) == 0 {
return nil, nil
}
client := dnsdisc.NewClient(dnsdisc.Config{})
return client.NewIterator(ctxc.config.DiscoveryURLs...)
}