move time checks into block.go and add time source mechanism

types/block.go

@@ -17,6 +17,7 @@ import (
 	"github.com/tendermint/tendermint/libs/bits"
 	tmbytes "github.com/tendermint/tendermint/libs/bytes"
 	tmmath "github.com/tendermint/tendermint/libs/math"
+	tmtime "github.com/tendermint/tendermint/libs/time"
 	tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
 	"github.com/tendermint/tendermint/version"
 )
@@ -94,6 +95,25 @@ func (b *Block) ValidateBasic() error {
 	return nil
 }
 
+// IsTimely validates that the block timestamp is 'timely' according to the proposer-based timestamp algorithm.
+// To evaluate if a block is timely, its timestamp is compared to the local time of the validator along with the configured
+// Precision and MsgDelay parameters.
+// Specifically, a proposed block timestamp is considered timely if it is satisfies the following inequalities:
+//
+// proposedBlockTime < validatorLocalTime + Precision + MsgDelay && proposedBlockTime > validatorLocaltime - Precision.
+//
+// For more information on the meaning of 'timely', see the proposer-based timestamp specification:
+// https://github.com/tendermint/spec/tree/master/spec/consensus/proposer-based-timestamp
+func (b *Block) IsTimely(clock tmtime.Source, p TimestampParams) bool {
+	lt := clock.Now()
+	lhs := lt.Add(-p.Precision).UnixMilli()
+	rhs := lt.Add(p.Precision).Add(p.MsgDelay).UnixMilli()
+	if lhs < b.Header.Time.UnixMilli() && b.Header.Time.UnixMilli() < rhs {
+		return true
+	}
+	return false
+}
+
 // fillHeader fills in any remaining header fields that are a function of the block data
 func (b *Block) fillHeader() {
 	if b.LastCommitHash == nil {

types/block_test.go

@@ -24,6 +24,7 @@ import (
 	"github.com/tendermint/tendermint/libs/bytes"
 	tmrand "github.com/tendermint/tendermint/libs/rand"
 	tmtime "github.com/tendermint/tendermint/libs/time"
+	tmtimemocks "github.com/tendermint/tendermint/libs/time/mocks"
 	tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
 	tmversion "github.com/tendermint/tendermint/proto/tendermint/version"
 	"github.com/tendermint/tendermint/version"
@@ -1347,3 +1348,67 @@ func TestHeaderHashVector(t *testing.T) {
 		require.Equal(t, tc.expBytes, hex.EncodeToString(hash))
 	}
 }
+
+func TestIsTimely(t *testing.T) {
+	genesisTime, err := time.Parse(time.RFC3339, "2019-03-13T23:00:00Z")
+	require.NoError(t, err)
+	testCases := []struct {
+		name         string
+		blockTime    time.Time
+		localTime    time.Time
+		precision    time.Duration
+		msgDelay     time.Duration
+		expectTimely bool
+	}{
+		{
+			// Checking that the following inequality evaluates to true:
+			// 1 - 2 < 0 < 1 + 2 + 1
+			name:         "basic timely",
+			blockTime:    genesisTime,
+			localTime:    genesisTime.Add(1 * time.Millisecond),
+			precision:    time.Millisecond * 2,
+			msgDelay:     time.Millisecond,
+			expectTimely: true,
+		},
+		{
+			// Checking that the following inequality evaluates to false:
+			// 3 - 2 < 0 < 3 + 2 + 1
+			name:         "local time too large",
+			blockTime:    genesisTime,
+			localTime:    genesisTime.Add(3 * time.Millisecond),
+			precision:    time.Millisecond * 2,
+			msgDelay:     time.Millisecond,
+			expectTimely: false,
+		},
+		{
+			// Checking that the following inequality evaluates to false:
+			// 0 - 2 < 2 < 2 + 1
+			name:         "block time too large",
+			blockTime:    genesisTime.Add(4 * time.Millisecond),
+			localTime:    genesisTime,
+			precision:    time.Millisecond * 2,
+			msgDelay:     time.Millisecond,
+			expectTimely: false,
+		},
+	}
+	for _, testCase := range testCases {
+		t.Run(testCase.name, func(t *testing.T) {
+			b := Block{
+				Header: Header{
+					Time: testCase.blockTime,
+				},
+			}
+
+			p := TimestampParams{
+				Precision: testCase.precision,
+				MsgDelay:  testCase.msgDelay,
+			}
+
+			mockSource := new(tmtimemocks.Source)
+			mockSource.On("Now").Return(testCase.localTime)
+
+			ti := b.IsTimely(mockSource, p)
+			assert.Equal(t, testCase.expectTimely, ti)
+		})
+	}
+}

types/params.go

@@ -75,6 +75,12 @@ type VersionParams struct {
 	AppVersion uint64 `json:"app_version"`
 }
 
+type TimestampParams struct {
+	Precision time.Duration `json:"precision"`
+	Accuracy  time.Duration `json:"accuracy"`
+	MsgDelay  time.Duration `json:"msg_delay"`
+}
+
 // DefaultConsensusParams returns a default ConsensusParams.
 func DefaultConsensusParams() *ConsensusParams {
 	return &ConsensusParams{