cmd/devp2p, p2p: dial using node iterator, discovery crawler (#20132)

* p2p/enode: add Iterator and associated utilities

* p2p/discover: add RandomNodes iterator

* p2p: dial using iterator

* cmd/devp2p: add discv4 crawler

* cmd/devp2p: WIP nodeset filter

* cmd/devp2p: fixup lesFilter

* core/forkid: add NewStaticFilter

* cmd/devp2p: make -eth-network filter actually work

* cmd/devp2p: improve crawl timestamp handling

* cmd/devp2p: fix typo

* p2p/enode: fix comment typos

* p2p/discover: fix comment typos

* p2p/discover: rename lookup.next to 'advance'

* p2p: lower discovery mixer timeout

* p2p/enode: implement dynamic FairMix timeouts

* cmd/devp2p: add ropsten support in -eth-network filter

* cmd/devp2p: tweak crawler log message

p2p/discover/table_util_test.go

@@ -17,11 +17,14 @@
 package discover
 
 import (
+	"bytes"
 	"crypto/ecdsa"
 	"encoding/hex"
+	"errors"
 	"fmt"
 	"math/rand"
 	"net"
+	"reflect"
 	"sort"
 	"sync"
 
@@ -169,6 +172,28 @@ func hasDuplicates(slice []*node) bool {
 	return false
 }
 
+func checkNodesEqual(got, want []*enode.Node) error {
+	if reflect.DeepEqual(got, want) {
+		return nil
+	}
+	output := new(bytes.Buffer)
+	fmt.Fprintf(output, "got %d nodes:\n", len(got))
+	for _, n := range got {
+		fmt.Fprintf(output, "  %v %v\n", n.ID(), n)
+	}
+	fmt.Fprintf(output, "want %d:\n", len(want))
+	for _, n := range want {
+		fmt.Fprintf(output, "  %v %v\n", n.ID(), n)
+	}
+	return errors.New(output.String())
+}
+
+func sortByID(nodes []*enode.Node) {
+	sort.Slice(nodes, func(i, j int) bool {
+		return string(nodes[i].ID().Bytes()) < string(nodes[j].ID().Bytes())
+	})
+}
+
 func sortedByDistanceTo(distbase enode.ID, slice []*node) bool {
 	return sort.SliceIsSorted(slice, func(i, j int) bool {
 		return enode.DistCmp(distbase, slice[i].ID(), slice[j].ID()) < 0