lite: follow up from tendermint#3989 (tendermint#4209)

* rename adjusted to adjacent

Refs tendermint#3989 (comment)

* rename ErrTooMuchChange to ErrNotEnoughVotingPowerSigned

Refs tendermint#3989 (comment)

* verify commit is properly signed

* remove no longer trusted headers

* restore trustedHeader and trustedNextVals

* check trustedHeader using options

Refs tendermint#4209 (comment)

* use correct var when checking if headers are adjacent

in bisection func
+ replace TODO with a comment

tendermint#3989 (comment)

* return header in VerifyHeaderAtHeight

because that way we avoid DB call

+ add godoc comments
+ check if there are no headers yet in AutoClient

tendermint#3989 (review)

* TestVerifyAdjacentHeaders: add 2 more test-cases

+ add TestVerifyReturnsErrorIfTrustLevelIsInvalid

* lite: avoid overflow when parsing key in db store!

* lite: rename AutoClient#Err to Errs

* lite: add a test for AutoClient

* lite: fix keyPattern and call itr.Next in db store

* lite: add two tests for db store

* lite: add TestClientRemovesNoLongerTrustedHeaders

* lite: test Client#Cleanup

* lite: test restoring trustedHeader

tendermint#4209 (comment)

* lite: comment out unused code in test_helpers

* fix TestVerifyReturnsErrorIfTrustLevelIsInvalid after merge

* change defaultRemoveNoLongerTrustedHeadersPeriod

and add docs

* write more doc

* lite: uncomment testable examples

* use stdlog.Fatal to stop AutoClient tests

* make lll linter happy

* separate errors for 2 cases

- the validator set of a skipped header cannot be trusted, i.e. <1/3rd
  of h1 validator set has signed (new error, something like
  ErrNewValSetCantBeTrusted)
- the validator set is trusted but < 2/3rds has signed
  (ErrNewHeaderCantBeTrusted)

tendermint#4209 (comment)

* remove all headers (even the last one) that are outside

of the trusting period. By doing this, we avoid checking the
trustedHeader's hash in checkTrustedHeaderUsingOptions (case #1).

tendermint#4209 (comment)

* explain restoreTrustedHeaderAndNextVals better

tendermint#4209 (comment)

* add ConfirmationFunction option

for optionally prompting for user input Y/n before removing headers

Refs tendermint#4209 (comment)

* make cleaning optional

tendermint#4209 (comment)

* return error when user refused to remove headers

* check for double votes in VerifyCommitTrusting

* leave only ErrNewValSetCantBeTrusted error

to differenciate between h2Vals.VerifyCommit and
h1NextVals.VerifyCommitTrusting

* fix example tests

* remove unnecessary if condition

tendermint#4209 (comment)

It will be handled by the above switch.

* verifyCommitBasic does not depend on vals

Co-authored-by: Marko <[email protected]>

lite/dynamic_verifier.go

@@ -185,7 +185,7 @@ func (dv *DynamicVerifier) Verify(shdr types.SignedHeader) error {
 
 // verifyAndSave will verify if this is a valid source full commit given the
 // best match trusted full commit, and if good, persist to dv.trusted.
-// Returns ErrTooMuchChange when >2/3 of trustedFC did not sign sourceFC.
+// Returns ErrNotEnoughVotingPowerSigned when >2/3 of trustedFC did not sign sourceFC.
 // Panics if trustedFC.Height() >= sourceFC.Height().
 func (dv *DynamicVerifier) verifyAndSave(trustedFC, sourceFC FullCommit) error {
 	if trustedFC.Height() >= sourceFC.Height() {
@@ -247,8 +247,8 @@ FOR_LOOP:
 			return sourceFC, nil
 		}
 
-		// Handle special case when err is ErrTooMuchChange.
-		if types.IsErrTooMuchChange(err) {
+		// Handle special case when err is ErrNotEnoughVotingPowerSigned.
+		if types.IsErrNotEnoughVotingPowerSigned(err) {
 			// Divide and conquer.
 			start, end := trustedFC.Height(), sourceFC.Height()
 			if !(start < end) {

lite2/auto_client.go

@@ -13,7 +13,7 @@ type AutoClient struct {
 	quit         chan struct{}
 
 	trustedHeaders chan *types.SignedHeader
-	err            chan error
+	errs           chan error
 }
 
 // NewAutoClient creates a new client and starts a polling goroutine.
@@ -23,7 +23,7 @@ func NewAutoClient(base *Client, updatePeriod time.Duration) *AutoClient {
 		updatePeriod:   updatePeriod,
 		quit:           make(chan struct{}),
 		trustedHeaders: make(chan *types.SignedHeader),
-		err:            make(chan error),
+		errs:           make(chan error),
 	}
 	go c.autoUpdate()
 	return c
@@ -35,8 +35,8 @@ func (c *AutoClient) TrustedHeaders() <-chan *types.SignedHeader {
 }
 
 // Err returns a channel onto which errors are posted.
-func (c *AutoClient) Err() <-chan error {
-	return c.err
+func (c *AutoClient) Errs() <-chan error {
+	return c.errs
 }
 
 // Stop stops the client.
@@ -45,30 +45,30 @@ func (c *AutoClient) Stop() {
 }
 
 func (c *AutoClient) autoUpdate() {
-	lastTrustedHeight, err := c.base.LastTrustedHeight()
-	if err != nil {
-		c.err <- err
-		return
-	}
-
 	ticker := time.NewTicker(c.updatePeriod)
 	defer ticker.Stop()
 
 	for {
 		select {
 		case <-ticker.C:
-			err := c.base.VerifyHeaderAtHeight(lastTrustedHeight+1, time.Now())
+			lastTrustedHeight, err := c.base.LastTrustedHeight()
 			if err != nil {
-				c.err <- err
+				c.errs <- err
+				continue
+			}
+
+			if lastTrustedHeight == -1 {
+				// no headers yet => wait
 				continue
 			}
-			h, err := c.base.TrustedHeader(lastTrustedHeight+1, time.Now())
+
+			h, err := c.base.VerifyHeaderAtHeight(lastTrustedHeight+1, time.Now())
 			if err != nil {
-				c.err <- err
+				// no header yet or verification error => try again after updatePeriod
+				c.errs <- err
 				continue
 			}
 			c.trustedHeaders <- h
-			lastTrustedHeight = h.Height
 		case <-c.quit:
 			return
 		}

lite2/auto_client_test.go

@@ -0,0 +1,76 @@
+package lite
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	dbm "github.com/tendermint/tm-db"
+
+	"github.com/tendermint/tendermint/libs/log"
+	mockp "github.com/tendermint/tendermint/lite2/provider/mock"
+	dbs "github.com/tendermint/tendermint/lite2/store/db"
+	"github.com/tendermint/tendermint/types"
+)
+
+func TestAutoClient(t *testing.T) {
+	const (
+		chainID = "TestAutoClient"
+	)
+
+	var (
+		keys = genPrivKeys(4)
+		// 20, 30, 40, 50 - the first 3 don't have 2/3, the last 3 do!
+		vals   = keys.ToValidators(20, 10)
+		bTime  = time.Now().Add(-1 * time.Hour)
+		header = keys.GenSignedHeader(chainID, 1, bTime, nil, vals, vals,
+			[]byte("app_hash"), []byte("cons_hash"), []byte("results_hash"), 0, len(keys))
+	)
+
+	base, err := NewClient(
+		chainID,
+		TrustOptions{
+			Period: 4 * time.Hour,
+			Height: 1,
+			Hash:   header.Hash(),
+		},
+		mockp.New(
+			chainID,
+			map[int64]*types.SignedHeader{
+				// trusted header
+				1: header,
+				// interim header (3/3 signed)
+				2: keys.GenSignedHeader(chainID, 2, bTime.Add(30*time.Minute), nil, vals, vals,
+					[]byte("app_hash"), []byte("cons_hash"), []byte("results_hash"), 0, len(keys)),
+				// last header (3/3 signed)
+				3: keys.GenSignedHeader(chainID, 3, bTime.Add(1*time.Hour), nil, vals, vals,
+					[]byte("app_hash"), []byte("cons_hash"), []byte("results_hash"), 0, len(keys)),
+			},
+			map[int64]*types.ValidatorSet{
+				1: vals,
+				2: vals,
+				3: vals,
+				4: vals,
+			},
+		),
+		dbs.New(dbm.NewMemDB(), chainID),
+	)
+	require.NoError(t, err)
+	base.SetLogger(log.TestingLogger())
+
+	c := NewAutoClient(base, 1*time.Second)
+	defer c.Stop()
+
+	for i := 2; i <= 3; i++ {
+		select {
+		case h := <-c.TrustedHeaders():
+			assert.EqualValues(t, i, h.Height)
+		case err := <-c.Errs():
+			require.NoError(t, err)
+		case <-time.After(2 * time.Second):
+			t.Fatal("no headers/errors received in 2 sec")
+		}
+	}
+}