new: Add GetRootHash bor api method

consensus/bor/api.go

@@ -17,10 +17,16 @@
 package bor
 
 import (
+	"math/big"
+	"sync"
+
 	"github.com/maticnetwork/bor/common"
 	"github.com/maticnetwork/bor/consensus"
 	"github.com/maticnetwork/bor/core/types"
+	"github.com/maticnetwork/bor/crypto"
 	"github.com/maticnetwork/bor/rpc"
+	"github.com/xsleonard/go-merkle"
+	"golang.org/x/crypto/sha3"
 )
 
 // API is a user facing RPC API to allow controlling the signer and voting
@@ -105,3 +111,41 @@ func (api *API) GetCurrentValidators() ([]*Validator, error) {
 	}
 	return snap.ValidatorSet.Validators, nil
 }
+
+// GetRootHash gets the current validators
+func (api *API) GetRootHash(start uint64, end uint64) ([]byte, error) {
+	blockHeaders := make([]*types.Header, end-start+1)
+	wg := new(sync.WaitGroup)
+	// do we want to limit the # of concurrent go routines?
+	for i := start; i <= end; i++ {
+		wg.Add(1)
+		go func(number uint64) {
+			blockHeaders[number-start] = api.chain.GetHeaderByNumber(number)
+			wg.Done()
+		}(i)
+	}
+	wg.Wait()
+
+	expectedLength := nextPowerOfTwo(end - start + 1)
+	headers := make([][32]byte, expectedLength)
+	for i := 0; i < len(blockHeaders); i++ {
+		blockHeader := blockHeaders[i]
+		header := crypto.Keccak256(appendBytes32(
+			blockHeader.Number.Bytes(),
+			new(big.Int).SetUint64(blockHeader.Time).Bytes(),
+			blockHeader.TxHash.Bytes(),
+			blockHeader.ReceiptHash.Bytes(),
+		))
+
+		var arr [32]byte
+		copy(arr[:], header)
+		headers[i] = arr
+	}
+
+	tree := merkle.NewTreeWithOpts(merkle.TreeOptions{EnableHashSorting: false, DisableHashLeaves: true})
+	if err := tree.Generate(convert(headers), sha3.NewLegacyKeccak256()); err != nil {
+		return nil, err
+	}
+
+	return tree.Root().Hash, nil
+}

consensus/bor/merkle.go

+package bor
+
+func appendBytes32(data ...[]byte) []byte {
+	var result []byte
+	for _, v := range data {
+		paddedV, err := convertTo32(v)
+		if err == nil {
+			result = append(result, paddedV[:]...)
+		}
+	}
+	return result
+}
+
+func nextPowerOfTwo(n uint64) uint64 {
+	if n == 0 {
+		return 1
+	}
+	// http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
+	n--
+	n |= n >> 1
+	n |= n >> 2
+	n |= n >> 4
+	n |= n >> 8
+	n |= n >> 16
+	n |= n >> 32
+	n++
+	return n
+}
+
+func convertTo32(input []byte) (output [32]byte, err error) {
+	l := len(input)
+	if l > 32 || l == 0 {
+		return
+	}
+	copy(output[32-l:], input[:])
+	return
+}
+
+func convert(input []([32]byte)) [][]byte {
+	var output [][]byte
+	for _, in := range input {
+		newInput := make([]byte, len(in[:]))
+		copy(newInput, in[:])
+		output = append(output, newInput)
+
+	}
+	return output
+}

go.mod

@@ -60,6 +60,7 @@ require (
 	github.com/syndtr/goleveldb v1.0.1-0.20190923125748-758128399b1d
 	github.com/tyler-smith/go-bip39 v1.0.1-0.20181017060643-dbb3b84ba2ef
 	github.com/wsddn/go-ecdh v0.0.0-20161211032359-48726bab9208
+	github.com/xsleonard/go-merkle v1.1.0
 	golang.org/x/crypto v0.0.0-20200311171314-f7b00557c8c4
 	golang.org/x/net v0.0.0-20200301022130-244492dfa37a
 	golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e

go.sum

@@ -176,6 +176,8 @@ github.com/tyler-smith/go-bip39 v1.0.1-0.20181017060643-dbb3b84ba2ef h1:wHSqTBrZ
 github.com/tyler-smith/go-bip39 v1.0.1-0.20181017060643-dbb3b84ba2ef/go.mod h1:sJ5fKU0s6JVwZjjcUEX2zFOnvq0ASQ2K9Zr6cf67kNs=
 github.com/wsddn/go-ecdh v0.0.0-20161211032359-48726bab9208 h1:1cngl9mPEoITZG8s8cVcUy5CeIBYhEESkOB7m6Gmkrk=
 github.com/wsddn/go-ecdh v0.0.0-20161211032359-48726bab9208/go.mod h1:IotVbo4F+mw0EzQ08zFqg7pK3FebNXpaMsRy2RT+Ees=
+github.com/xsleonard/go-merkle v1.1.0 h1:fHe1fuhJjGH22ZzVTAH0jqHLhTGhOq3wQjJN+8P0jQg=
+github.com/xsleonard/go-merkle v1.1.0/go.mod h1:cW4z+UZ/4f2n9IJgIiyDCdYguchoDyDAPmpuOWGxdGg=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2 h1:VklqNMn3ovrHsnt90PveolxSbWFaJdECFbxSq0Mqo2M=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20200311171314-f7b00557c8c4 h1:QmwruyY+bKbDDL0BaglrbZABEali68eoMFhTZpCjYVA=

internal/web3ext/web3ext.go

@@ -149,6 +149,11 @@ web3._extend({
 			call: 'bor_getCurrentValidators',
 			params: 0
 		}),
+		new web3._extend.Method({
+			name: 'getRootHash',
+			call: 'bor_getRootHash',
+			params: 2,
+		}),
 	]
 });
 `