From 0f90b9d59e1450d28054a5eb00a42fd9412cac89 Mon Sep 17 00:00:00 2001
From: Chengcheng Zhang <943420582@qq.com>
Date: Wed, 5 Jun 2019 21:36:31 +0800
Subject: [PATCH] add mac function, modify nextBlockTime (#122)

* add mac function, modify nextBlockTime

* delete max function

* update

* modify block timestamp

* update

* update

* update

* update

* update

* update

* update

* update
---
 consensus/general.go                    |  2 +-
 proposal/blockproposer/blockproposer.go | 13 ++++++++++---
 protocol/validation/block.go            |  7 ++++---
 protocol/validation/block_test.go       |  8 ++++----
 4 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/consensus/general.go b/consensus/general.go
index 47650f65..e048217e 100644
--- a/consensus/general.go
+++ b/consensus/general.go
@@ -32,7 +32,7 @@ const (
 	BlockTimeInterval = 500
 
 	// MaxTimeOffsetMs is the maximum number of seconds a block time is allowed to be ahead of the current time
-	MaxTimeOffsetMs  = uint64(60 * 60 * 1000)
+	MaxTimeOffsetMs  = uint64(BlockTimeInterval * BlockNumEachNode / 3)
 	MedianTimeBlocks = 11
 
 	PayToWitnessPubKeyHashDataSize = 20
diff --git a/proposal/blockproposer/blockproposer.go b/proposal/blockproposer/blockproposer.go
index 13ebf174..32105db3 100644
--- a/proposal/blockproposer/blockproposer.go
+++ b/proposal/blockproposer/blockproposer.go
@@ -52,9 +52,16 @@ func (b *BlockProposer) generateBlocks() {
 
 		bestBlockHeader := b.chain.BestBlockHeader()
 		bestBlockHash := bestBlockHeader.Hash()
-		nextBlockTime := uint64(time.Now().UnixNano() / 1e6)
-		if minNextBlockTime := bestBlockHeader.Timestamp + consensus.BlockTimeInterval; nextBlockTime < minNextBlockTime {
-			nextBlockTime = minNextBlockTime
+
+		now := uint64(time.Now().UnixNano() / 1e6)
+		base := now
+		if now < bestBlockHeader.Timestamp {
+			base = bestBlockHeader.Timestamp
+		}
+		minTimeToNextBlock := consensus.BlockTimeInterval - base%consensus.BlockTimeInterval
+		nextBlockTime := base + minTimeToNextBlock
+		if (nextBlockTime - now) < consensus.BlockTimeInterval/10 {
+			nextBlockTime += consensus.BlockTimeInterval
 		}
 
 		isBlocker, err := b.chain.IsBlocker(&bestBlockHash, xpubStr, nextBlockTime)
diff --git a/protocol/validation/block.go b/protocol/validation/block.go
index 8b63df0e..630a87d4 100644
--- a/protocol/validation/block.go
+++ b/protocol/validation/block.go
@@ -26,13 +26,14 @@ var (
 )
 
 func checkBlockTime(b *bc.Block, parent *state.BlockNode) error {
-	if b.Timestamp > uint64(time.Now().UnixNano()/int64(time.Millisecond))+consensus.MaxTimeOffsetMs {
+	now := uint64(time.Now().UnixNano() / 1e6)
+	if b.Timestamp < (parent.Timestamp + consensus.BlockTimeInterval) {
 		return errBadTimestamp
 	}
-
-	if b.Timestamp <= parent.CalcPastMedianTime() {
+	if b.Timestamp > (now + consensus.MaxTimeOffsetMs) {
 		return errBadTimestamp
 	}
+
 	return nil
 }
 
diff --git a/protocol/validation/block_test.go b/protocol/validation/block_test.go
index 99e152ef..6f126c0d 100644
--- a/protocol/validation/block_test.go
+++ b/protocol/validation/block_test.go
@@ -21,15 +21,15 @@ func TestCheckBlockTime(t *testing.T) {
 		err        error
 	}{
 		{
-			blockTime:  1520000001,
+			blockTime:  1520000500,
 			parentTime: []uint64{1520000000},
 			err:        nil,
 		},
 		{
 			desc:       "timestamp less than past median time (blocktest#1005)",
-			blockTime:  1510000094,
-			parentTime: []uint64{1520000000, 1510000099, 1510000098, 1510000097, 1510000096, 1510000095, 1510000094, 1510000093, 1510000092, 1510000091, 1510000090},
-			err:        errBadTimestamp,
+			blockTime:  1520005500,
+			parentTime: []uint64{1520000000, 1520000500, 1520001000, 1520001500, 1520002000, 1520002500, 1520003000, 1520003500, 1520004000, 1520004500, 1520005000},
+			err:        nil,
 		},
 		{
 			desc:       "timestamp greater than max limit (blocktest#1006)",
-- 
2.11.0