evidence: remove ConflictingHeaders type (#5317)

## Description

Remove ConflictingHeaders & compositeEvidence types


Ref #5288

light/client.go

@@ -931,10 +931,7 @@ func (c *Client) compareNewHeaderWithWitnesses(l *types.LightBlock, now time.Tim
 	defer c.providerMutex.Unlock()
 
 	// 1. Make sure AT LEAST ONE witness returns the same header.
-	var (
-		headerMatched      bool
-		lastErrConfHeaders error
-	)
+	var headerMatched bool
 	for attempt := uint16(1); attempt <= c.maxRetryAttempts; attempt++ {
 		if len(c.witnesses) == 0 {
 			return errNoWitnesses{}
@@ -955,10 +952,6 @@ func (c *Client) compareNewHeaderWithWitnesses(l *types.LightBlock, now time.Tim
 			switch e := err.(type) {
 			case nil: // at least one header matched
 				headerMatched = true
-			case ErrConflictingHeaders: // fork detected
-				c.logger.Info("FORK DETECTED", "witness", e.Witness, "err", err)
-				c.sendConflictingHeadersEvidence(&types.ConflictingHeadersEvidence{H1: e.H1, H2: e.H2})
-				lastErrConfHeaders = e
 			case errBadWitness:
 				c.logger.Info("Bad witness", "witness", c.witnesses[e.WitnessIndex], "err", err)
 				// if witness sent us invalid header / vals, remove it
@@ -973,11 +966,7 @@ func (c *Client) compareNewHeaderWithWitnesses(l *types.LightBlock, now time.Tim
 			c.removeWitness(idx)
 		}
 
-		if lastErrConfHeaders != nil {
-			// NOTE: all of the potential forks will be reported, but we only return
-			// the last ErrConflictingHeaders error here.
-			return lastErrConfHeaders
-		} else if headerMatched {
+		if headerMatched {
 			return nil
 		}
 
@@ -1003,7 +992,6 @@ func (c *Client) compareNewHeaderWithWitness(errc chan error, l *types.LightBloc
 			errc <- errBadWitness{bsErr, invalidLightBlock, witnessIndex}
 			return
 		}
-		errc <- ErrConflictingHeaders{H1: l.SignedHeader, Primary: c.primary, H2: altBlock.SignedHeader, Witness: witness}
 	}
 
 	errc <- nil
@@ -1120,25 +1108,6 @@ func (c *Client) validateLightBlock(l *types.LightBlock, expectedHeight int64) e
 	return nil
 }
 
-// sendConflictingHeadersEvidence sends evidence to all witnesses and primary
-// on best effort basis.
-//
-// Evidence needs to be submitted to all full nodes since there's no way to
-// determine which full node is correct (honest).
-func (c *Client) sendConflictingHeadersEvidence(ev *types.ConflictingHeadersEvidence) {
-	err := c.primary.ReportEvidence(ev)
-	if err != nil {
-		c.logger.Error("Failed to report evidence to primary", "ev", ev, "primary", c.primary)
-	}
-
-	for _, w := range c.witnesses {
-		err := w.ReportEvidence(ev)
-		if err != nil {
-			c.logger.Error("Failed to report evidence to witness", "ev", ev, "witness", w)
-		}
-	}
-}
-
 // exponential backoff (with jitter)
 //		0.5s -> 2s -> 4.5s -> 8s -> 12.5 with 1s variation
 func backoffTimeout(attempt uint16) time.Duration {

light/client_test.go

@@ -973,46 +973,6 @@ func TestClient_TrustedValidatorSet(t *testing.T) {
 	assert.Equal(t, 1, len(c.Witnesses()))
 }
 
-func TestClientReportsConflictingHeadersEvidence(t *testing.T) {
-	// fullNode2 sends us different header
-	altH2 := keys.GenSignedHeaderLastBlockID(chainID, 2, bTime.Add(30*time.Minute), nil, vals, vals,
-		hash("app_hash2"), hash("cons_hash"), hash("results_hash"),
-		0, len(keys), types.BlockID{Hash: h1.Hash()})
-	fullNode2 := mockp.New(
-		chainID,
-		map[int64]*types.SignedHeader{
-			1: h1,
-			2: altH2,
-		},
-		map[int64]*types.ValidatorSet{
-			1: vals,
-			2: vals,
-		},
-	)
-
-	c, err := light.NewClient(
-		chainID,
-		trustOptions,
-		fullNode,
-		[]provider.Provider{fullNode2},
-		dbs.New(dbm.NewMemDB(), chainID),
-		light.Logger(log.TestingLogger()),
-		light.MaxRetryAttempts(1),
-	)
-	require.NoError(t, err)
-
-	// Check verification returns an error.
-	_, err = c.VerifyLightBlockAtHeight(2, bTime.Add(2*time.Hour))
-	if assert.Error(t, err) {
-		assert.Contains(t, err.Error(), "does not match one")
-	}
-
-	// Check evidence was sent to both full nodes.
-	ev := &types.ConflictingHeadersEvidence{H1: h2, H2: altH2}
-	assert.True(t, fullNode2.HasEvidence(ev))
-	assert.True(t, fullNode.HasEvidence(ev))
-}
-
 func TestClientPrunesHeadersAndValidatorSets(t *testing.T) {
 	c, err := light.NewClient(
 		chainID,

light/errors.go

@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"time"
 
-	"github.com/tendermint/tendermint/light/provider"
 	"github.com/tendermint/tendermint/types"
 )
 
@@ -40,22 +39,6 @@ func (e ErrInvalidHeader) Error() string {
 	return fmt.Sprintf("invalid header: %v", e.Reason)
 }
 
-// ErrConflictingHeaders is thrown when two conflicting headers are discovered.
-type ErrConflictingHeaders struct {
-	H1      *types.SignedHeader
-	Primary provider.Provider
-
-	H2      *types.SignedHeader
-	Witness provider.Provider
-}
-
-func (e ErrConflictingHeaders) Error() string {
-	return fmt.Sprintf(
-		"header hash %X from primary %v does not match one %X from witness %v",
-		e.H1.Hash(), e.Primary,
-		e.H2.Hash(), e.Witness)
-}
-
 // ErrVerificationFailed means either sequential or skipping verification has
 // failed to verify from header #1 to header #2 due to some reason.
 type ErrVerificationFailed struct {