les, light: LES/2 protocol version (#14970)

This PR implements the new LES protocol version extensions:

* new and more efficient Merkle proofs reply format (when replying to
  a multiple Merkle proofs request, we just send a single set of trie
  nodes containing all necessary nodes)
* BBT (BloomBitsTrie) works similarly to the existing CHT and contains
  the bloombits search data to speed up log searches
* GetTxStatusMsg returns the inclusion position or the
  pending/queued/unknown state of a transaction referenced by hash
* an optional signature of new block data (number/hash/td) can be
  included in AnnounceMsg to provide an option for "very light
  clients" (mobile/embedded devices) to skip expensive Ethash check
  and accept multiple signatures of somewhat trusted servers (still a
  lot better than trusting a single server completely and retrieving
  everything through RPC). The new client mode is not implemented in
  this PR, just the protocol extension.

light/nodeset.go

@@ -0,0 +1,141 @@
+// Copyright 2014 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum 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 go-ethereum 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 go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package light
+
+import (
+	"errors"
+	"sync"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/trie"
+)
+
+// NodeSet stores a set of trie nodes. It implements trie.Database and can also
+// act as a cache for another trie.Database.
+type NodeSet struct {
+	db       map[string][]byte
+	dataSize int
+	lock     sync.RWMutex
+}
+
+// NewNodeSet creates an empty node set
+func NewNodeSet() *NodeSet {
+	return &NodeSet{
+		db: make(map[string][]byte),
+	}
+}
+
+// Put stores a new node in the set
+func (db *NodeSet) Put(key []byte, value []byte) error {
+	db.lock.Lock()
+	defer db.lock.Unlock()
+
+	if _, ok := db.db[string(key)]; !ok {
+		db.db[string(key)] = common.CopyBytes(value)
+		db.dataSize += len(value)
+	}
+	return nil
+}
+
+// Get returns a stored node
+func (db *NodeSet) Get(key []byte) ([]byte, error) {
+	db.lock.RLock()
+	defer db.lock.RUnlock()
+
+	if entry, ok := db.db[string(key)]; ok {
+		return entry, nil
+	}
+	return nil, errors.New("not found")
+}
+
+// Has returns true if the node set contains the given key
+func (db *NodeSet) Has(key []byte) (bool, error) {
+	_, err := db.Get(key)
+	return err == nil, nil
+}
+
+// KeyCount returns the number of nodes in the set
+func (db *NodeSet) KeyCount() int {
+	db.lock.RLock()
+	defer db.lock.RUnlock()
+
+	return len(db.db)
+}
+
+// DataSize returns the aggregated data size of nodes in the set
+func (db *NodeSet) DataSize() int {
+	db.lock.RLock()
+	defer db.lock.RUnlock()
+
+	return db.dataSize
+}
+
+// NodeList converts the node set to a NodeList
+func (db *NodeSet) NodeList() NodeList {
+	db.lock.RLock()
+	defer db.lock.RUnlock()
+
+	var values NodeList
+	for _, value := range db.db {
+		values = append(values, value)
+	}
+	return values
+}
+
+// Store writes the contents of the set to the given database
+func (db *NodeSet) Store(target trie.Database) {
+	db.lock.RLock()
+	defer db.lock.RUnlock()
+
+	for key, value := range db.db {
+		target.Put([]byte(key), value)
+	}
+}
+
+// NodeList stores an ordered list of trie nodes. It implements trie.DatabaseWriter.
+type NodeList []rlp.RawValue
+
+// Store writes the contents of the list to the given database
+func (n NodeList) Store(db trie.Database) {
+	for _, node := range n {
+		db.Put(crypto.Keccak256(node), node)
+	}
+}
+
+// NodeSet converts the node list to a NodeSet
+func (n NodeList) NodeSet() *NodeSet {
+	db := NewNodeSet()
+	n.Store(db)
+	return db
+}
+
+// Put stores a new node at the end of the list
+func (n *NodeList) Put(key []byte, value []byte) error {
+	*n = append(*n, value)
+	return nil
+}
+
+// DataSize returns the aggregated data size of nodes in the list
+func (n NodeList) DataSize() int {
+	var size int
+	for _, node := range n {
+		size += len(node)
+	}
+	return size
+}