les: expose les server API

eth/backend.go

@@ -54,6 +54,7 @@ import (
 type LesServer interface {
 	Start(srvr *p2p.Server)
 	Stop()
+	APIs() []rpc.API
 	Protocols() []p2p.Protocol
 	SetBloomBitsIndexer(bbIndexer *core.ChainIndexer)
 }
@@ -247,6 +248,11 @@ func (s *Ethereum) APIs() []rpc.API {
 	// Append any APIs exposed explicitly by the consensus engine
 	apis = append(apis, s.engine.APIs(s.BlockChain())...)
 
+	// Append any APIs exposed explicitly by the les server
+	if s.lesServer != nil {
+		apis = append(apis, s.lesServer.APIs()...)
+	}
+
 	// Append all the local APIs and return
 	return append(apis, []rpc.API{
 		{

internal/web3ext/web3ext.go

@@ -30,6 +30,7 @@ var Modules = map[string]string{
 	"shh":        Shh_JS,
 	"swarmfs":    SWARMFS_JS,
 	"txpool":     TxPool_JS,
+	"les":        LES_JS,
 }
 
 const Chequebook_JS = `
@@ -631,3 +632,17 @@ web3._extend({
 	]
 });
 `
+
+const LES_JS = `
+web3._extend({
+	property: 'les',
+	methods: [],
+	properties: 
+	[
+		new web3._extend.Property({
+			name: 'checkpoint',
+			getter: 'les_checkpoint'
+		}),
+	]
+});
+`

les/api.go

@@ -0,0 +1,60 @@
+// Copyright 2018 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 les
+
+import (
+	"errors"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
+)
+
+var (
+	errNoStableCheckpoint = errors.New("no stable checkpoint provided")
+)
+
+// PublicLesServerAPI  provides an API to access the les server.
+// It offers only methods that operate on public data that is freely available to anyone.
+type PublicLesServerAPI struct {
+	server *LesServer
+}
+
+// NewPublicLesServerAPI creates a new les server API.
+func NewPublicLesServerAPI(server *LesServer) *PublicLesServerAPI {
+	return &PublicLesServerAPI{
+		server: server,
+	}
+}
+
+// Checkpoint returns the latest checkpoint package.
+//
+// The checkpoint package consists of 4 strings:
+//   result[0], hex encoded latest section index
+//   result[1], 32 bytes hex encoded latest section head hash
+//   result[2], 32 bytes hex encoded latest section canonical hash trie root hash
+//   result[3], 32 bytes hex encoded latest section bloom trie root hash
+func (api *PublicLesServerAPI) Checkpoint() ([4]string, error) {
+	var res [4]string
+	sectionIdx, sectionHead, chtRoot, bloomTrieRoot := api.server.getCheckpoint()
+	if sectionHead == (common.Hash{}) || chtRoot == (common.Hash{}) || bloomTrieRoot == (common.Hash{}) {
+		return res, errNoStableCheckpoint
+	}
+	res[0] = hexutil.Encode(big.NewInt(int64(sectionIdx)).Bytes())
+	res[1], res[2], res[3] = sectionHead.Hex(), chtRoot.Hex(), bloomTrieRoot.Hex()
+	return res, nil
+}

les/server.go

@@ -35,6 +35,7 @@ import (
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/p2p/discv5"
 	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/rpc"
 )
 
 type LesServer struct {
@@ -142,6 +143,46 @@ func (s *LesServer) Stop() {
 	s.protocolManager.Stop()
 }
 
+// APIs implements LesServer, returns all API service provided by les server.
+func (s *LesServer) APIs() []rpc.API {
+	return []rpc.API{
+		{
+			Namespace: "les",
+			Version:   "1.0",
+			Service:   NewPublicLesServerAPI(s),
+			Public:    true,
+		},
+	}
+}
+
+// getCheckpoint finds the common stored section index and returns a set of
+// post-processed trie roots (CHT and BloomTrie) associated with
+// the appropriate section index and head hash as a checkpoint package.
+//
+// Note for cht, the section size in LES1 is 4K, so indexer still uses LES/1
+// 4k section size for backwards server compatibility. For bloomTrie, the size
+// of the section used for indexer is 32K.
+func (s *LesServer) getCheckpoint() (uint64, common.Hash, common.Hash, common.Hash) {
+	chtCount, _, _ := s.chtIndexer.Sections()
+	bloomTrieCount, _, _ := s.bloomTrieIndexer.Sections()
+	count := chtCount / (light.CHTFrequencyClient / light.CHTFrequencyServer)
+	// Cap the section index if the two sections are not consistent.
+	if count > bloomTrieCount {
+		count = bloomTrieCount
+	}
+	if count == 0 {
+		// No checkpoint information can be provided.
+		return 0, common.Hash{}, common.Hash{}, common.Hash{}
+	}
+	// convert last LES/2 section index back to LES/1 index for chtIndexer.SectionHead
+	latest := count*(light.CHTFrequencyClient/light.CHTFrequencyServer) - 1
+
+	sectionHead := s.chtIndexer.SectionHead(latest)
+	chtRoot := light.GetChtRoot(s.protocolManager.chainDb, latest, sectionHead)
+	bloomTrieRoot := light.GetBloomTrieRoot(s.protocolManager.chainDb, count-1, sectionHead)
+	return count - 1, sectionHead, chtRoot, bloomTrieRoot
+}
+
 type requestCosts struct {
 	baseCost, reqCost uint64
 }