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seed.go
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seed.go
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package connmgr
import (
"fmt"
"github.com/p9c/duod/pkg/chaincfg"
mrand "math/rand"
"net"
"strconv"
"time"
"github.com/p9c/duod/pkg/wire"
)
const (
// These constants are used by the DNS seed code to pick a random last seen time.
secondsIn3Days int32 = 24 * 60 * 60 * 3
secondsIn4Days int32 = 24 * 60 * 60 * 4
)
// OnSeed is the signature of the callback function which is invoked when DNS seeding is succesful
type OnSeed func(addrs []*wire.NetAddress)
// LookupFunc is the signature of the DNS lookup function.
type LookupFunc func(string) ([]net.IP, error)
// SeedFromDNS uses DNS seeding to populate the address manager with peers.
func SeedFromDNS(
chainParams *chaincfg.Params, reqServices wire.ServiceFlag,
lookupFn LookupFunc, seedFn OnSeed,
) {
for _, dnsseed := range chainParams.DNSSeeds {
var host string
if !dnsseed.HasFiltering || reqServices == wire.SFNodeNetwork {
host = dnsseed.Host
} else {
host = fmt.Sprintf("x%x.%s", uint64(reqServices), dnsseed.Host)
}
go func(host string) {
randSource := mrand.New(mrand.NewSource(time.Now().UnixNano()))
seedpeers, e := lookupFn(host)
if e != nil {
E.F("DNS routeable failed on seed %s: %v", host, e)
return
}
numPeers := len(seedpeers)
D.F("%d addresses found from DNS seed %s", numPeers, host)
if numPeers == 0 {
return
}
addresses := make([]*wire.NetAddress, len(seedpeers))
// if this errors then we have *real* problems
intPort, _ := strconv.Atoi(chainParams.DefaultPort)
for i, peer := range seedpeers {
addresses[i] = wire.NewNetAddressTimestamp(
// bitcoind seeds with addresses from a time randomly
// selected between 3 and 7 days ago.
time.Now().Add(
-1*time.Second*time.Duration(
secondsIn3Days+
randSource.Int31n(secondsIn4Days),
),
),
0, peer, uint16(intPort),
)
}
seedFn(addresses)
}(host)
}
}