Merge pull request #77 from hyperledger-labs/query-header

Add QueryHeader method to ProverI

Signed-off-by: Jun Kimura <jun.kimura@datachain.jp>

chains/tendermint/prover.go

@@ -78,13 +78,18 @@ func (pr *Prover) QueryPacketAcknowledgementCommitmentWithProof(height int64, se
 	return pr.chain.queryPacketAcknowledgementCommitment(height, seq, true)
 }
 
+// QueryHeader returns the header corresponding to the height
+func (pr *Prover) QueryHeader(height int64) (out core.HeaderI, err error) {
+	return pr.queryHeaderAtHeight(height)
+}
+
 // QueryLatestHeader returns the latest header from the chain
 func (pr *Prover) QueryLatestHeader() (out core.HeaderI, err error) {
 	var h int64
 	if h, err = pr.chain.GetLatestHeight(); err != nil {
 		return nil, err
 	}
-	return pr.queryHeaderAtHeight(h)
+	return pr.QueryHeader(h)
 }
 
 // GetLatestLightHeight uses the CLI utilities to pull the latest height from a given chain

core/provers.go

@@ -29,6 +29,9 @@ type LightClientI interface {
 	// GetChainID returns the chain ID
 	GetChainID() string
 
+	// QueryHeader returns the header corresponding to the height
+	QueryHeader(height int64) (out HeaderI, err error)
+
 	// QueryLatestHeader returns the latest header from the chain
 	QueryLatestHeader() (out HeaderI, err error)
 

provers/mock/prover.go

@@ -3,6 +3,7 @@ package mock
 import (
 	"context"
 	"crypto/sha256"
+	"fmt"
 	"time"
 
 	"github.com/cosmos/cosmos-sdk/codec"
@@ -46,6 +47,14 @@ func (pr *Prover) GetChainID() string {
 	return pr.chain.ChainID()
 }
 
+// QueryHeader returns the header corresponding to the height
+func (pr *Prover) QueryHeader(height int64) (out core.HeaderI, err error) {
+	if height != int64(pr.sequence) {
+		return nil, fmt.Errorf("mock prover does not support querying old headers: got=%v latest=%v", height, pr.sequence)
+	}
+	return pr.QueryLatestHeader()
+}
+
 // QueryLatestHeader returns the latest header from the chain
 func (pr *Prover) QueryLatestHeader() (out core.HeaderI, err error) {
 	var header = mocktypes.Header{