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https://github.com/FlipsideCrypto/dcrd.git
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900bbf14ef
This modifies the SeedFromDNS function to accept a string of the DNS seeds as well as the default port instead of a concrete chaincfg.Params to remove the tight coupling between the two packages at the API boundary and allow callers to easily provide custom values if desired.
70 lines
1.9 KiB
Go
70 lines
1.9 KiB
Go
// Copyright (c) 2016 The btcsuite developers
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// Copyright (c) 2019 The Decred developers
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// Use of this source code is governed by an ISC
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// license that can be found in the LICENSE file.
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package connmgr
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import (
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"fmt"
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mrand "math/rand"
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"net"
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"time"
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"github.com/decred/dcrd/wire"
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)
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const (
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// These constants are used by the DNS seed code to pick a random last
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// seen time.
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secondsIn3Days int32 = 24 * 60 * 60 * 3
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secondsIn4Days int32 = 24 * 60 * 60 * 4
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)
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// OnSeed is the signature of the callback function which is invoked when DNS
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// seeding is successful.
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type OnSeed func(addrs []*wire.NetAddress)
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// LookupFunc is the signature of the DNS lookup function.
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type LookupFunc func(string) ([]net.IP, error)
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// SeedFromDNS uses DNS seeding to populate the address manager with peers.
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func SeedFromDNS(dnsSeeds []string, defaultPort uint16, reqServices wire.ServiceFlag, lookupFn LookupFunc, seedFn OnSeed) {
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for _, seed := range dnsSeeds {
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host := seed
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if reqServices != wire.SFNodeNetwork {
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host = fmt.Sprintf("x%x.%s", uint64(reqServices), seed)
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}
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go func(host string) {
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randSource := mrand.New(mrand.NewSource(time.Now().UnixNano()))
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seedpeers, err := lookupFn(host)
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if err != nil {
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log.Infof("DNS discovery failed on seed %s: %v", host, err)
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return
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}
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numPeers := len(seedpeers)
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log.Infof("%d addresses found from DNS seed %s", numPeers, host)
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if numPeers == 0 {
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return
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}
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addresses := make([]*wire.NetAddress, len(seedpeers))
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// if this errors then we have *real* problems
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for i, peer := range seedpeers {
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addresses[i] = wire.NewNetAddressTimestamp(
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// bitcoind seeds with addresses from
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// a time randomly selected between 3
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// and 7 days ago.
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time.Now().Add(-1*time.Second*time.Duration(secondsIn3Days+
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randSource.Int31n(secondsIn4Days))),
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0, peer, defaultPort)
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}
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seedFn(addresses)
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}(host)
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}
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}
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