Merge branch 'master' into erik/curve25519-x25519

lite2/client.go

@@ -121,9 +121,9 @@ type Client struct {
 	// Where trusted headers are stored.
 	trustedStore store.Store
 	// Highest trusted header from the store (height=H).
-	trustedHeader *types.SignedHeader
+	latestTrustedHeader *types.SignedHeader
 	// Highest next validator set from the store (height=H+1).
-	trustedNextVals *types.ValidatorSet
+	latestTrustedNextVals *types.ValidatorSet
 
 	// See UpdatePeriod option
 	updatePeriod time.Duration
@@ -164,13 +164,13 @@ func NewClient(
 		return nil, err
 	}
 
-	if c.trustedHeader != nil {
+	if c.latestTrustedHeader != nil {
 		if err := c.checkTrustedHeaderUsingOptions(trustOptions); err != nil {
 			return nil, err
 		}
 	}
 
-	if c.trustedHeader == nil || c.trustedHeader.Height < trustOptions.Height {
+	if c.latestTrustedHeader == nil || c.latestTrustedHeader.Height < trustOptions.Height {
 		if err := c.initializeWithTrustOptions(trustOptions); err != nil {
 			return nil, err
 		}
@@ -253,8 +253,8 @@ func (c *Client) restoreTrustedHeaderAndNextVals() error {
 			return errors.Wrap(err, "can't get last trusted next validators")
 		}
 
-		c.trustedHeader = trustedHeader
-		c.trustedNextVals = trustedNextVals
+		c.latestTrustedHeader = trustedHeader
+		c.latestTrustedNextVals = trustedNextVals
 
 		c.logger.Debug("Restored trusted header and next vals", lastHeight)
 	}
@@ -283,24 +283,24 @@ func (c *Client) restoreTrustedHeaderAndNextVals() error {
 func (c *Client) checkTrustedHeaderUsingOptions(options TrustOptions) error {
 	var primaryHash []byte
 	switch {
-	case options.Height > c.trustedHeader.Height:
-		h, err := c.signedHeaderFromPrimary(c.trustedHeader.Height)
+	case options.Height > c.latestTrustedHeader.Height:
+		h, err := c.signedHeaderFromPrimary(c.latestTrustedHeader.Height)
 		if err != nil {
 			return err
 		}
 		primaryHash = h.Hash()
-	case options.Height == c.trustedHeader.Height:
+	case options.Height == c.latestTrustedHeader.Height:
 		primaryHash = options.Hash
-	case options.Height < c.trustedHeader.Height:
+	case options.Height < c.latestTrustedHeader.Height:
 		c.logger.Info("Client initialized with old header (trusted is more recent)",
 			"old", options.Height,
-			"trustedHeight", c.trustedHeader.Height,
-			"trustedHash", hash2str(c.trustedHeader.Hash()))
+			"trustedHeight", c.latestTrustedHeader.Height,
+			"trustedHash", hash2str(c.latestTrustedHeader.Hash()))
 
 		action := fmt.Sprintf(
 			"Rollback to %d (%X)? Note this will remove newer headers up to %d (%X)",
 			options.Height, options.Hash,
-			c.trustedHeader.Height, c.trustedHeader.Hash())
+			c.latestTrustedHeader.Height, c.latestTrustedHeader.Hash())
 		if c.confirmationFn(action) {
 			// remove all the headers (options.Height, trustedHeader.Height]
 			c.cleanup(options.Height + 1)
@@ -314,13 +314,13 @@ func (c *Client) checkTrustedHeaderUsingOptions(options TrustOptions) error {
 		primaryHash = options.Hash
 	}
 
-	if !bytes.Equal(primaryHash, c.trustedHeader.Hash()) {
+	if !bytes.Equal(primaryHash, c.latestTrustedHeader.Hash()) {
 		c.logger.Info("Prev. trusted header's hash (h1) doesn't match hash from primary provider (h2)",
-			"h1", c.trustedHeader.Hash(), "h1", primaryHash)
+			"h1", hash2str(c.latestTrustedHeader.Hash()), "h2", hash2str(primaryHash))
 
 		action := fmt.Sprintf(
 			"Prev. trusted header's hash %X doesn't match hash %X from primary provider. Remove all the stored headers?",
-			c.trustedHeader.Hash(), primaryHash)
+			c.latestTrustedHeader.Hash(), primaryHash)
 		if c.confirmationFn(action) {
 			err := c.Cleanup()
 			if err != nil {
@@ -449,14 +449,7 @@ func (c *Client) TrustedHeader(height int64, now time.Time) (*types.SignedHeader
 
 	// 2) Get header from store.
 	h, err := c.trustedStore.SignedHeader(height)
-	switch {
-	case errors.Is(err, store.ErrSignedHeaderNotFound):
-		// 2.1) If not found, try to fetch header from primary.
-		h, err = c.fetchMissingTrustedHeader(height, now)
-		if err != nil {
-			return nil, err
-		}
-	case err != nil:
+	if err != nil {
 		return nil, err
 	}
 
@@ -523,15 +516,25 @@ func (c *Client) ChainID() string {
 	return c.chainID
 }
 
-// VerifyHeaderAtHeight fetches the header and validators at the given height
-// and calls VerifyHeader.
+// VerifyHeaderAtHeight fetches header and validators at the given height
+// and calls VerifyHeader. It returns header immediately if such exists in
+// trustedStore (no verification is needed).
 //
-// If the trusted header is more recent than one here, an error is returned.
-// If the header is not found by the primary provider,
-// provider.ErrSignedHeaderNotFound error is returned.
+// It returns provider.ErrSignedHeaderNotFound if header is not found by
+// primary.
+// It returns ErrOldHeaderExpired if header expired.
 func (c *Client) VerifyHeaderAtHeight(height int64, now time.Time) (*types.SignedHeader, error) {
-	if c.trustedHeader.Height >= height {
-		return nil, errors.Errorf("header at more recent height #%d exists", c.trustedHeader.Height)
+	if height <= 0 {
+		return nil, errors.New("negative or zero height")
+	}
+
+	h, err := c.TrustedHeader(height, now)
+	switch err.(type) {
+	case nil: // Return already trusted header
+		c.logger.Info("Header has already been verified", "height", height, "hash", hash2str(h.Hash()))
+		return h, nil
+	case ErrOldHeaderExpired:
+		return nil, err
 	}
 
 	// Request the header and the vals.
@@ -540,10 +543,12 @@ func (c *Client) VerifyHeaderAtHeight(height int64, now time.Time) (*types.Signe
 		return nil, err
 	}
 
-	return newHeader, c.VerifyHeader(newHeader, newVals, now)
+	return newHeader, c.verifyHeader(newHeader, newVals, now)
 }
 
-// VerifyHeader verifies new header against the trusted state.
+// VerifyHeader verifies new header against the trusted state. It returns
+// immediately if newHeader exists in trustedStore (no verification is
+// needed).
 //
 // SequentialVerification: verifies that 2/3 of the trusted validator set has
 // signed the new header. If the headers are not adjacent, **all** intermediate
@@ -555,7 +560,7 @@ func (c *Client) VerifyHeaderAtHeight(height int64, now time.Time) (*types.Signe
 // intermediate headers will be requested. See the specification for details.
 // https://github.com/tendermint/spec/blob/master/spec/consensus/light-client.md
 //
-// If the trusted header is more recent than one here, an error is returned.
+// It returns ErrOldHeaderExpired if newHeader expired.
 //
 // If, at any moment, SignedHeader or ValidatorSet are not found by the primary
 // provider, provider.ErrSignedHeaderNotFound /
@@ -565,21 +570,49 @@ func (c *Client) VerifyHeaderAtHeight(height int64, now time.Time) (*types.Signe
 // validator set at height newHeader.Height+1 (i.e.
 // newHeader.NextValidatorsHash).
 func (c *Client) VerifyHeader(newHeader *types.SignedHeader, newVals *types.ValidatorSet, now time.Time) error {
+	h, err := c.TrustedHeader(newHeader.Height, now)
+	switch err.(type) {
+	case nil: // Return already trusted header
+		// Make sure it's the same header.
+		if !bytes.Equal(h.Hash(), newHeader.Hash()) {
+			return errors.Errorf("existing trusted header %X does not match newHeader %X", h.Hash(), newHeader.Hash())
+		}
+		c.logger.Info("Header has already been verified",
+			"height", newHeader.Height, "hash", hash2str(newHeader.Hash()))
+		return nil
+	case ErrOldHeaderExpired:
+		return err
+	}
+
+	return c.verifyHeader(newHeader, newVals, now)
+}
+
+func (c *Client) verifyHeader(newHeader *types.SignedHeader, newVals *types.ValidatorSet, now time.Time) error {
 	c.logger.Info("VerifyHeader", "height", newHeader.Height, "hash", hash2str(newHeader.Hash()),
 		"vals", hash2str(newVals.Hash()))
 
-	if c.trustedHeader.Height >= newHeader.Height {
-		return errors.Errorf("header at more recent height #%d exists", c.trustedHeader.Height)
-	}
-
 	var err error
-	switch c.verificationMode {
-	case sequential:
-		err = c.sequence(c.trustedHeader, c.trustedNextVals, newHeader, newVals, now)
-	case skipping:
-		err = c.bisection(c.trustedHeader, c.trustedNextVals, newHeader, newVals, now)
-	default:
-		panic(fmt.Sprintf("Unknown verification mode: %b", c.verificationMode))
+
+	// 1) If going forward, perform either bisection or sequential verification
+	if newHeader.Height >= c.latestTrustedHeader.Height {
+		switch c.verificationMode {
+		case sequential:
+			err = c.sequence(c.latestTrustedHeader, c.latestTrustedNextVals, newHeader, newVals, now)
+		case skipping:
+			err = c.bisection(c.latestTrustedHeader, c.latestTrustedNextVals, newHeader, newVals, now)
+		default:
+			panic(fmt.Sprintf("Unknown verification mode: %b", c.verificationMode))
+		}
+	} else {
+		// 2) Otherwise, perform backwards verification
+		// Find the closest trusted header after newHeader.Height
+		var closestHeader *types.SignedHeader
+		closestHeader, err = c.trustedStore.SignedHeaderAfter(newHeader.Height)
+		if err != nil {
+			return errors.Wrapf(err, "can't get signed header after height %d", newHeader.Height)
+		}
+
+		err = c.backwards(closestHeader, newHeader, now)
 	}
 	if err != nil {
 		c.logger.Error("Can't verify", "err", err)
@@ -596,6 +629,7 @@ func (c *Client) VerifyHeader(newHeader *types.SignedHeader, newVals *types.Vali
 	if err != nil {
 		return err
 	}
+
 	return c.updateTrustedHeaderAndNextVals(newHeader, nextVals)
 }
 
@@ -652,8 +686,8 @@ func (c *Client) cleanup(stopHeight int64) error {
 		}
 	}
 
-	c.trustedHeader = nil
-	c.trustedNextVals = nil
+	c.latestTrustedHeader = nil
+	c.latestTrustedNextVals = nil
 	err = c.restoreTrustedHeaderAndNextVals()
 	if err != nil {
 		return err
@@ -682,8 +716,8 @@ func (c *Client) sequence(
 		}
 
 		c.logger.Debug("Verify newHeader against trustedHeader",
-			"trustedHeight", c.trustedHeader.Height,
-			"trustedHash", hash2str(c.trustedHeader.Hash()),
+			"trustedHeight", c.latestTrustedHeader.Height,
+			"trustedHash", hash2str(c.latestTrustedHeader.Hash()),
 			"newHeight", interimHeader.Height,
 			"newHash", hash2str(interimHeader.Hash()))
 		err = VerifyAdjacent(c.chainID, trustedHeader, interimHeader, trustedNextVals,
@@ -709,7 +743,7 @@ func (c *Client) sequence(
 	}
 
 	// 2) Verify the new header.
-	return VerifyAdjacent(c.chainID, c.trustedHeader, newHeader, newVals, c.trustingPeriod, now)
+	return VerifyAdjacent(c.chainID, c.latestTrustedHeader, newHeader, newVals, c.trustingPeriod, now)
 }
 
 // see VerifyHeader
@@ -779,8 +813,8 @@ func (c *Client) updateTrustedHeaderAndNextVals(h *types.SignedHeader, nextVals
 		return errors.Wrap(err, "failed to save trusted header")
 	}
 
-	c.trustedHeader = h
-	c.trustedNextVals = nextVals
+	c.latestTrustedHeader = h
+	c.latestTrustedNextVals = nextVals
 
 	return nil
 }
@@ -799,77 +833,44 @@ func (c *Client) fetchHeaderAndValsAtHeight(height int64) (*types.SignedHeader,
 	return h, vals, nil
 }
 
-// fetchMissingTrustedHeader finds the closest height after the
-// requested height and does backwards verification.
-func (c *Client) fetchMissingTrustedHeader(height int64, now time.Time) (*types.SignedHeader, error) {
-	c.logger.Info("Fetching missing header", "height", height)
-
-	closestHeader, err := c.trustedStore.SignedHeaderAfter(height)
-	if err != nil {
-		return nil, errors.Wrapf(err, "can't get signed header after %d", height)
-	}
-
-	// Perform backwards verification from closestHeader to header at the given
-	// height.
-	h, err := c.backwards(height, closestHeader, now)
-	if err != nil {
-		return nil, err
-	}
-
-	// Fetch next validator set from primary and persist it.
-	nextVals, err := c.validatorSetFromPrimary(height + 1)
-	if err != nil {
-		return nil, errors.Wrapf(err, "failed to obtain the vals #%d", height)
-	}
-	if !bytes.Equal(h.NextValidatorsHash, nextVals.Hash()) {
-		return nil, errors.Errorf("expected next validator's hash %X, but got %X",
-			h.NextValidatorsHash, nextVals.Hash())
-	}
-	if err := c.trustedStore.SaveSignedHeaderAndNextValidatorSet(h, nextVals); err != nil {
-		return nil, errors.Wrap(err, "failed to save trusted header")
-	}
-
-	return h, nil
-}
-
 // Backwards verification (see VerifyHeaderBackwards func in the spec)
-func (c *Client) backwards(toHeight int64, fromHeader *types.SignedHeader, now time.Time) (*types.SignedHeader, error) {
+func (c *Client) backwards(trustedHeader *types.SignedHeader, newHeader *types.SignedHeader,
+	now time.Time) error {
 	var (
-		trustedHeader   = fromHeader
-		untrustedHeader *types.SignedHeader
-		err             error
+		interimHeader *types.SignedHeader
+		err           error
 	)
 
-	for i := trustedHeader.Height - 1; i >= toHeight; i-- {
-		untrustedHeader, err = c.signedHeaderFromPrimary(i)
+	for trustedHeader.Height > newHeader.Height {
+		interimHeader, err = c.signedHeaderFromPrimary(trustedHeader.Height - 1)
 		if err != nil {
-			return nil, errors.Wrapf(err, "failed to obtain the header #%d", i)
+			return errors.Wrapf(err, "failed to obtain the header at height #%d", trustedHeader.Height-1)
 		}
 
-		if err := untrustedHeader.ValidateBasic(c.chainID); err != nil {
-			return nil, errors.Wrap(err, "untrustedHeader.ValidateBasic failed")
+		if err := interimHeader.ValidateBasic(c.chainID); err != nil {
+			return errors.Wrap(err, "untrustedHeader.ValidateBasic failed")
 		}
 
-		if !untrustedHeader.Time.Before(trustedHeader.Time) {
-			return nil, errors.Errorf("expected older header time %v to be before newer header time %v",
-				untrustedHeader.Time,
+		if !interimHeader.Time.Before(trustedHeader.Time) {
+			return errors.Errorf("expected older header time %v to be before newer header time %v",
+				interimHeader.Time,
 				trustedHeader.Time)
 		}
 
-		if HeaderExpired(untrustedHeader, c.trustingPeriod, now) {
-			return nil, ErrOldHeaderExpired{untrustedHeader.Time.Add(c.trustingPeriod), now}
+		if HeaderExpired(interimHeader, c.trustingPeriod, now) {
+			return ErrOldHeaderExpired{interimHeader.Time.Add(c.trustingPeriod), now}
 		}
 
-		if !bytes.Equal(untrustedHeader.Hash(), trustedHeader.LastBlockID.Hash) {
-			return nil, errors.Errorf("older header hash %X does not match trusted header's last block %X",
-				untrustedHeader.Hash(),
+		if !bytes.Equal(interimHeader.Hash(), trustedHeader.LastBlockID.Hash) {
+			return errors.Errorf("older header hash %X does not match trusted header's last block %X",
+				interimHeader.Hash(),
 				trustedHeader.LastBlockID.Hash)
 		}
 
-		trustedHeader = untrustedHeader
+		trustedHeader = interimHeader
 	}
 
-	return trustedHeader, nil
+	return nil
 }
 
 // compare header with all witnesses provided.
@@ -899,7 +900,7 @@ func (c *Client) compareNewHeaderWithWitnesses(h *types.SignedHeader) error {
 			}
 
 			if !bytes.Equal(h.Hash(), altH.Hash()) {
-				if err = c.trustedNextVals.VerifyCommitTrusting(c.chainID, altH.Commit.BlockID,
+				if err = c.latestTrustedNextVals.VerifyCommitTrusting(c.chainID, altH.Commit.BlockID,
 					altH.Height, altH.Commit, c.trustLevel); err != nil {
 					c.logger.Error("Witness sent us incorrect header", "err", err, "witness", witness)
 					witnessesToRemove = append(witnessesToRemove, i)
@@ -989,7 +990,7 @@ func (c *Client) RemoveNoLongerTrustedHeaders(now time.Time) {
 	// 3) Remove all headers that are outside of the trusting period.
 	//
 	// NOTE: even the latest header can be removed. it's okay because
-	// c.trustedHeader will retain it in memory so other funcs like VerifyHeader
+	// c.latestTrustedHeader will retain it in memory so other funcs like VerifyHeader
 	// don't crash.
 	for height := oldestHeight; height <= latestHeight; height++ {
 		h, err := c.trustedStore.SignedHeader(height)

lite2/client_test.go

@@ -732,7 +732,7 @@ func TestClientReplacesPrimaryWithWitnessIfPrimaryIsUnavailable(t *testing.T) {
 	assert.Equal(t, 1, len(c.Witnesses()))
 }
 
-func TestClient_TrustedHeaderFetchesMissingHeader(t *testing.T) {
+func TestClient_BackwardsVerification(t *testing.T) {
 	c, err := NewClient(
 		chainID,
 		TrustOptions{
@@ -752,16 +752,16 @@ func TestClient_TrustedHeaderFetchesMissingHeader(t *testing.T) {
 	defer c.Stop()
 
 	// 1) header is missing => expect no error
-	h, err := c.TrustedHeader(2, bTime.Add(1*time.Hour).Add(1*time.Second))
+	h, err := c.VerifyHeaderAtHeight(2, bTime.Add(1*time.Hour).Add(1*time.Second))
 	require.NoError(t, err)
 	if assert.NotNil(t, h) {
 		assert.EqualValues(t, 2, h.Height)
 	}
 
 	// 2) header is missing, but it's expired => expect error
-	h, err = c.TrustedHeader(1, bTime.Add(1*time.Hour).Add(1*time.Second))
+	h, err = c.VerifyHeaderAtHeight(1, bTime.Add(1*time.Hour).Add(1*time.Second))
 	assert.Error(t, err)
-	assert.Nil(t, h)
+	assert.NotNil(t, h)
 }
 
 func TestClient_NewClientFromTrustedStore(t *testing.T) {