Release v0.1.0

vendor/github.com/btcsuite/btcd/connmgr/seed.go

@@ -0,0 +1,75 @@
+// Copyright (c) 2016 The btcsuite developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+package connmgr
+
+import (
+	"fmt"
+	mrand "math/rand"
+	"net"
+	"strconv"
+	"time"
+
+	"github.com/btcsuite/btcd/chaincfg"
+	"github.com/btcsuite/btcd/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 succesfull.
+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, err := lookupFn(host)
+			if err != nil {
+				log.Infof("DNS discovery failed on seed %s: %v", host, err)
+				return
+			}
+			numPeers := len(seedpeers)
+
+			log.Infof("%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)
+	}
+}