ingest/ledgerbackend: Add prev ledger hash check to CaptiveStellarCore (

#3257) Adds an extra check in `GetLedger` checking if previously read ledger header match the current ledger previous hash. `CaptiveStellarCore` reads ledgers in a strict increasing order. It's worth checking if the previous hash is match to ensure we receive ledgers in correct order.
stellar · Nov 27, 2020 · 7fa5a54 · 7fa5a54
1 parent 423317f
commit 7fa5a54
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Showing 4 changed files with 183 additions and 26 deletions.
diff --git a/ingest/ledgerbackend/captive_core_backend.go b/ingest/ledgerbackend/captive_core_backend.go
@@ -91,8 +91,9 @@ type CaptiveStellarCore struct {
 	// cachedMeta keeps that ledger data of the last fetched ledger. Updated in GetLedger().
 	cachedMeta *xdr.LedgerCloseMeta
 
-	nextLedger uint32  // next ledger expected, error w/ restart if not seen
-	lastLedger *uint32 // end of current segment if offline, nil if online
+	nextLedger         uint32  // next ledger expected, error w/ restart if not seen
+	lastLedger         *uint32 // end of current segment if offline, nil if online
+	previousLedgerHash *string
 
 	// waitIntervalPrepareRange defines a time to wait between checking if the buffer
 	// is empty. Default 1s, lower in tests to make them faster.
@@ -265,6 +266,18 @@ func (c *CaptiveStellarCore) openOnlineReplaySubprocess(from uint32) error {
 
 	c.nextLedger = nextLedger
 	c.lastLedger = nil
+
+	if c.ledgerHashStore != nil {
+		var exists bool
+		ledgerHash, exists, err = c.ledgerHashStore.GetLedgerHash(nextLedger - 1)
+		if err != nil {
+			return errors.Wrapf(err, "error trying to read ledger hash %d", nextLedger-1)
+		}
+		if exists {
+			c.previousLedgerHash = &ledgerHash
+		}
+	}
+
 	c.blocking = false
 
 	// read-ahead buffer
@@ -486,10 +499,30 @@ loop:
 		seq := result.LedgerCloseMeta.LedgerSequence()
 		if seq != c.nextLedger {
 			// We got something unexpected; close and reset
-			errOut = errors.Errorf("unexpected ledger (expected=%d actual=%d)", c.nextLedger, seq)
+			errOut = errors.Errorf(
+				"unexpected ledger sequence (expected=%d actual=%d)",
+				c.nextLedger,
+				seq,
+			)
 			break
 		}
+
+		newPreviousLedgerHash := result.LedgerCloseMeta.PreviousLedgerHash().HexString()
+		if c.previousLedgerHash != nil && *c.previousLedgerHash != newPreviousLedgerHash {
+			// We got something unexpected; close and reset
+			errOut = errors.Errorf(
+				"unexpected previous ledger hash for ledger %d (expected=%s actual=%s)",
+				seq,
+				*c.previousLedgerHash,
+				newPreviousLedgerHash,
+			)
+			break
+		}
+
 		c.nextLedger++
+		currentLedgerHash := result.LedgerCloseMeta.LedgerHash().HexString()
+		c.previousLedgerHash = &currentLedgerHash
+
 		if seq == sequence {
 			// Found the requested seq
 			c.cachedMeta = result.LedgerCloseMeta
@@ -554,6 +587,7 @@ func (c *CaptiveStellarCore) Close() error {
 
 	c.nextLedger = 0
 	c.lastLedger = nil
+	c.previousLedgerHash = nil
 
 	return nil
 }

diff --git a/ingest/ledgerbackend/captive_core_backend_test.go b/ingest/ledgerbackend/captive_core_backend_test.go
@@ -55,21 +55,41 @@ func (m *stellarCoreRunnerMock) close() error {
 
 func (m *stellarCoreRunnerMock) setLogger(*log.Entry) {}
 
-func buildLedgerCloseMeta(sequence uint32) xdr.LedgerCloseMeta {
+func buildLedgerCloseMeta(header testLedgerHeader) xdr.LedgerCloseMeta {
 	opResults := []xdr.OperationResult{}
 	opMeta := []xdr.OperationMeta{}
 
 	tmpHash, _ := hex.DecodeString("cde54da3901f5b9c0331d24fbb06ac9c5c5de76de9fb2d4a7b86c09e46f11d8c")
 	var hash [32]byte
 	copy(hash[:], tmpHash)
 
+	var ledgerHash [32]byte
+	if header.hash != "" {
+		tmpHash, err := hex.DecodeString(header.hash)
+		if err != nil {
+			panic(err)
+		}
+		copy(ledgerHash[:], tmpHash)
+	}
+
+	var previousLedgerHash [32]byte
+	if header.hash != "" {
+		tmpHash, err := hex.DecodeString(header.previousLedgerHash)
+		if err != nil {
+			panic(err)
+		}
+		copy(previousLedgerHash[:], tmpHash)
+	}
+
 	source := xdr.MustAddress("GAEJJMDDCRYF752PKIJICUVL7MROJBNXDV2ZB455T7BAFHU2LCLSE2LW")
 	return xdr.LedgerCloseMeta{
 		V: 0,
 		V0: &xdr.LedgerCloseMetaV0{
 			LedgerHeader: xdr.LedgerHeaderHistoryEntry{
+				Hash: ledgerHash,
 				Header: xdr.LedgerHeader{
-					LedgerSeq: xdr.Uint32(sequence),
+					LedgerSeq:          xdr.Uint32(header.sequence),
+					PreviousLedgerHash: previousLedgerHash,
 				},
 			},
 			TxSet: xdr.TransactionSet{
@@ -79,7 +99,7 @@ func buildLedgerCloseMeta(sequence uint32) xdr.LedgerCloseMeta {
 						V1: &xdr.TransactionV1Envelope{
 							Tx: xdr.Transaction{
 								SourceAccount: source.ToMuxedAccount(),
-								Fee:           xdr.Uint32(sequence),
+								Fee:           xdr.Uint32(header.sequence),
 							},
 						},
 					},
@@ -90,7 +110,7 @@ func buildLedgerCloseMeta(sequence uint32) xdr.LedgerCloseMeta {
 					Result: xdr.TransactionResultPair{
 						TransactionHash: xdr.Hash(hash),
 						Result: xdr.TransactionResult{
-							FeeCharged: xdr.Int64(sequence),
+							FeeCharged: xdr.Int64(header.sequence),
 							Result: xdr.TransactionResultResult{
 								Code:    xdr.TransactionResultCodeTxSuccess,
 								Results: &opResults,
@@ -107,8 +127,14 @@ func buildLedgerCloseMeta(sequence uint32) xdr.LedgerCloseMeta {
 
 }
 
-func writeLedgerHeader(w io.Writer, sequence uint32) {
-	err := xdr.MarshalFramed(w, buildLedgerCloseMeta(sequence))
+type testLedgerHeader struct {
+	sequence           uint32
+	hash               string
+	previousLedgerHash string
+}
+
+func writeLedgerHeader(w io.Writer, header testLedgerHeader) {
+	err := xdr.MarshalFramed(w, buildLedgerCloseMeta(header))
 	if err != nil {
 		panic(err)
 	}
@@ -144,7 +170,7 @@ func TestCaptivePrepareRange(t *testing.T) {
 	// Core will actually start with the last checkpoint before the from ledger
 	// and then rewind to the `from` ledger.
 	for i := 64; i <= 99; i++ {
-		writeLedgerHeader(&buf, uint32(i))
+		writeLedgerHeader(&buf, testLedgerHeader{sequence: uint32(i)})
 	}
 
 	exitChan := make(chan struct{})
@@ -456,7 +482,7 @@ func TestCaptivePrepareRangeUnboundedRange_ReuseSession(t *testing.T) {
 	var buf bytes.Buffer
 
 	for i := 2; i <= 65; i++ {
-		writeLedgerHeader(&buf, uint32(i))
+		writeLedgerHeader(&buf, testLedgerHeader{sequence: uint32(i)})
 	}
 
 	mockRunner := &stellarCoreRunnerMock{}
@@ -497,7 +523,7 @@ func TestGetLatestLedgerSequence(t *testing.T) {
 	var buf bytes.Buffer
 
 	for i := 2; i <= 200; i++ {
-		writeLedgerHeader(&buf, uint32(i))
+		writeLedgerHeader(&buf, testLedgerHeader{sequence: uint32(i)})
 	}
 
 	exitChan := make(chan struct{})
@@ -561,7 +587,7 @@ func TestCaptiveGetLedger(t *testing.T) {
 	tt := assert.New(t)
 	var buf bytes.Buffer
 	for i := 64; i <= 66; i++ {
-		writeLedgerHeader(&buf, uint32(i))
+		writeLedgerHeader(&buf, testLedgerHeader{sequence: uint32(i)})
 	}
 
 	mockRunner := &stellarCoreRunnerMock{}
@@ -624,10 +650,10 @@ func TestCaptiveGetLedger_NextLedgerIsDifferentToLedgerFromBuffer(t *testing.T)
 	tt := assert.New(t)
 	var buf bytes.Buffer
 	for i := 64; i <= 65; i++ {
-		writeLedgerHeader(&buf, uint32(i))
+		writeLedgerHeader(&buf, testLedgerHeader{sequence: uint32(i)})
 	}
 
-	writeLedgerHeader(&buf, uint32(68))
+	writeLedgerHeader(&buf, testLedgerHeader{sequence: uint32(68)})
 
 	mockRunner := &stellarCoreRunnerMock{}
 	mockRunner.On("catchup", uint32(65), uint32(66)).Return(nil)
@@ -654,7 +680,7 @@ func TestCaptiveGetLedger_NextLedgerIsDifferentToLedgerFromBuffer(t *testing.T)
 	assert.NoError(t, err)
 
 	_, _, err = captiveBackend.GetLedger(66)
-	tt.EqualError(err, "unexpected ledger (expected=66 actual=68)")
+	tt.EqualError(err, "unexpected ledger sequence (expected=66 actual=68)")
 }
 func TestCaptiveGetLedger_ErrReadingMetaResult(t *testing.T) {
 	tt := assert.New(t)
@@ -695,7 +721,7 @@ func TestCaptiveGetLedger_ErrClosingAfterLastLedger(t *testing.T) {
 	tt := assert.New(t)
 	var buf bytes.Buffer
 	for i := 64; i <= 66; i++ {
-		writeLedgerHeader(&buf, uint32(i))
+		writeLedgerHeader(&buf, testLedgerHeader{sequence: uint32(i)})
 	}
 
 	mockRunner := &stellarCoreRunnerMock{}
@@ -734,7 +760,7 @@ func TestCaptiveGetLedger_BoundedGetLedgerAfterCoreExit(t *testing.T) {
 	tt := assert.New(t)
 	var buf bytes.Buffer
 	for i := 64; i <= 70; i++ {
-		writeLedgerHeader(&buf, uint32(i))
+		writeLedgerHeader(&buf, testLedgerHeader{sequence: uint32(i)})
 	}
 
 	mockRunner := &stellarCoreRunnerMock{}
@@ -783,7 +809,7 @@ func TestCaptiveGetLedger_BoundedGetLedgerAfterCoreExit(t *testing.T) {
 func TestCaptiveGetLedger_CloseBufferFull(t *testing.T) {
 	var buf bytes.Buffer
 	for i := 2; i <= 200; i++ {
-		writeLedgerHeader(&buf, uint32(i))
+		writeLedgerHeader(&buf, testLedgerHeader{sequence: uint32(i)})
 	}
 
 	mockRunner := &stellarCoreRunnerMock{}
@@ -843,9 +869,9 @@ func waitForBufferToFill(captiveBackend *CaptiveStellarCore) {
 
 func TestGetLedgerBoundsCheck(t *testing.T) {
 	var buf bytes.Buffer
-	writeLedgerHeader(&buf, 128)
-	writeLedgerHeader(&buf, 129)
-	writeLedgerHeader(&buf, 130)
+	writeLedgerHeader(&buf, testLedgerHeader{sequence: 128})
+	writeLedgerHeader(&buf, testLedgerHeader{sequence: 129})
+	writeLedgerHeader(&buf, testLedgerHeader{sequence: 130})
 
 	mockRunner := &stellarCoreRunnerMock{}
 	exitChan := make(chan struct{})
@@ -892,9 +918,9 @@ func TestGetLedgerBoundsCheck(t *testing.T) {
 	mockRunner.AssertExpectations(t)
 
 	buf.Reset()
-	writeLedgerHeader(&buf, 64)
-	writeLedgerHeader(&buf, 65)
-	writeLedgerHeader(&buf, 66)
+	writeLedgerHeader(&buf, testLedgerHeader{sequence: 64})
+	writeLedgerHeader(&buf, testLedgerHeader{sequence: 65})
+	writeLedgerHeader(&buf, testLedgerHeader{sequence: 66})
 
 	mockRunner.On("catchup", uint32(64), uint32(66)).Return(nil).Once()
 	mockRunner.On("getProcessExitChan").Return(exitChan)
@@ -941,7 +967,7 @@ func TestCaptiveGetLedgerTerminated(t *testing.T) {
 		},
 	}
 
-	go writeLedgerHeader(writer, 64)
+	go writeLedgerHeader(writer, testLedgerHeader{sequence: 64})
 	err := captiveBackend.PrepareRange(BoundedRange(64, 100))
 	assert.NoError(t, err)
 
@@ -1109,3 +1135,85 @@ func TestCaptiveIsPrepared(t *testing.T) {
 		})
 	}
 }
+
+// TestCaptivePreviousLedgerCheck checks if previousLedgerHash is set in PrepareRange
+// and then checked and updated in GetLedger.
+func TestCaptivePreviousLedgerCheck(t *testing.T) {
+	var buf bytes.Buffer
+
+	h := 3
+	for i := 192; i <= 300; i++ {
+		writeLedgerHeader(&buf, testLedgerHeader{
+			sequence:           uint32(i),
+			hash:               fmt.Sprintf("%02x00000000000000000000000000000000000000000000000000000000000000", h),
+			previousLedgerHash: fmt.Sprintf("%02x00000000000000000000000000000000000000000000000000000000000000", h-1),
+		})
+		h++
+	}
+
+	// Write invalid hash
+	writeLedgerHeader(&buf, testLedgerHeader{
+		sequence:           301,
+		hash:               "0000000000000000000000000000000000000000000000000000000000000000",
+		previousLedgerHash: "0000000000000000000000000000000000000000000000000000000000000000",
+	})
+
+	ch := make(chan struct{})
+	mockRunner := &stellarCoreRunnerMock{}
+	mockRunner.On("runFrom", uint32(254), "0101010100000000000000000000000000000000000000000000000000000000").Return(nil).Once()
+	mockRunner.On("getMetaPipe").Return(&buf)
+	mockRunner.On("getProcessExitChan").Return(ch)
+	mockRunner.On("getProcessExitError").Return(nil).Maybe()
+	mockRunner.On("close").Run(func(args mock.Arguments) {
+		close(ch)
+	}).Return(nil)
+	defer mockRunner.AssertExpectations(t)
+
+	mockArchive := &historyarchive.MockArchive{}
+	mockArchive.
+		On("GetRootHAS").
+		Return(historyarchive.HistoryArchiveState{
+			CurrentLedger: uint32(255),
+		}, nil)
+	mockArchive.
+		On("GetLedgerHeader", uint32(255)).
+		Return(xdr.LedgerHeaderHistoryEntry{
+			Header: xdr.LedgerHeader{
+				PreviousLedgerHash: xdr.Hash{1, 1, 1, 1},
+			},
+		}, nil).Once()
+	defer mockArchive.AssertExpectations(t)
+
+	mockLedgerHashStore := &MockLedgerHashStore{}
+	mockLedgerHashStore.On("GetLedgerHash", uint32(254)).
+		Return("", false, nil).Once()
+	mockLedgerHashStore.On("GetLedgerHash", uint32(191)).
+		Return("0200000000000000000000000000000000000000000000000000000000000000", true, nil).Once()
+	defer mockLedgerHashStore.AssertExpectations(t)
+
+	captiveBackend := CaptiveStellarCore{
+		configPath:        "stellar-core.cfg",
+		archive:           mockArchive,
+		networkPassphrase: network.PublicNetworkPassphrase,
+		stellarCoreRunnerFactory: func(configPath string) (stellarCoreRunnerInterface, error) {
+			return mockRunner, nil
+		},
+		ledgerHashStore: mockLedgerHashStore,
+	}
+
+	err := captiveBackend.PrepareRange(UnboundedRange(300))
+	assert.NoError(t, err)
+
+	exists, meta, err := captiveBackend.GetLedger(300)
+	assert.NoError(t, err)
+	assert.True(t, exists)
+	assert.NotNil(t, captiveBackend.previousLedgerHash)
+	assert.Equal(t, uint32(301), captiveBackend.nextLedger)
+	assert.Equal(t, meta.LedgerHash().HexString(), *captiveBackend.previousLedgerHash)
+
+	_, _, err = captiveBackend.GetLedger(301)
+	assert.EqualError(t, err, "unexpected previous ledger hash for ledger 301 (expected=6f00000000000000000000000000000000000000000000000000000000000000 actual=0000000000000000000000000000000000000000000000000000000000000000)")
+
+	err = captiveBackend.Close()
+	assert.NoError(t, err)
+}
diff --git a/xdr/hash.go b/xdr/hash.go
@@ -0,0 +1,7 @@
+package xdr
+
+import "encoding/hex"
+
+func (h Hash) HexString() string {
+	return hex.EncodeToString(h[:])
+}
diff --git a/xdr/ledger_close_meta.go b/xdr/ledger_close_meta.go
@@ -3,3 +3,11 @@ package xdr
 func (l LedgerCloseMeta) LedgerSequence() uint32 {
 	return uint32(l.MustV0().LedgerHeader.Header.LedgerSeq)
 }
+
+func (l LedgerCloseMeta) LedgerHash() Hash {
+	return l.MustV0().LedgerHeader.Hash
+}
+
+func (l LedgerCloseMeta) PreviousLedgerHash() Hash {
+	return l.MustV0().LedgerHeader.Header.PreviousLedgerHash
+}