fix: end exclusive data commitment range fix (#1058)

## Description

Fixes celestiaorg/orchestrator-relayer#432

#### PR checklist

- [ ] Tests written/updated
- [ ] Changelog entry added in `.changelog` (we use
[unclog](https://github.com/informalsystems/unclog) to manage our
changelog)
- [ ] Updated relevant documentation (`docs/` or `spec/`) and code
comments

---------

Co-authored-by: Rootul P <rootulp@gmail.com>

rpc/core/blocks.go

@@ -318,9 +318,10 @@ func validateDataCommitmentRange(start uint64, end uint64) error {
 	if start >= end {
 		return fmt.Errorf("last block is smaller than first block")
 	}
-	if end > uint64(env.BlockStore.Height()) {
+	// the data commitment range is end exclusive
+	if end > uint64(env.BlockStore.Height())+1 {
 		return fmt.Errorf(
-			"last block %d is higher than current chain height %d",
+			"end block %d is higher than current chain height %d",
 			end,
 			env.BlockStore.Height(),
 		)

rpc/core/blocks_test.go

@@ -168,6 +168,11 @@ func TestDataCommitmentResults(t *testing.T) {
 		{0, 1000, false},
 		{0, 10, false},
 		{10, 8, false},
+		// to test the end exclusive support for ranges.
+		// the end block could be equal to (height+1), but the data commitment would only
+		// take up to height. So we should be able to send request having end block equal
+		// to (height+1).
+		{int(env.BlockStore.Height()) - 100, int(env.BlockStore.Height()) + 1, true},
 	}
 
 	for i, tc := range testCases {
@@ -333,10 +338,10 @@ func (indexer mockBlockIndexer) Search(ctx context.Context, _ *query.Query) ([]i
 	return results, nil
 }
 
-// randomBlocks generates a set of random blocks up to the provided height.
+// randomBlocks generates a set of random blocks up to (and including) the provided height.
 func randomBlocks(height int64) []*types.Block {
-	blocks := make([]*types.Block, height)
-	for i := int64(0); i < height; i++ {
+	blocks := make([]*types.Block, height+1)
+	for i := int64(0); i <= height; i++ {
 		blocks[i] = randomBlock(i)
 	}
 	return blocks