rpc: add method block_by_hash (#4257)

* added RPC method block_by_hash

* created hash => height

* changes typings

* block_by_hash changes

* Update store/store.go

Co-Authored-By: Anton Kaliaev <anton.kalyaev@gmail.com>

* Update store/store.go

Co-Authored-By: Anton Kaliaev <anton.kalyaev@gmail.com>

* Update store/store.go

Co-Authored-By: Anton Kaliaev <anton.kalyaev@gmail.com>

* Update store/store.go

Co-Authored-By: Anton Kaliaev <anton.kalyaev@gmail.com>

Co-authored-by: Marko <marbar3778@yahoo.com>
Co-authored-by: Anton Kaliaev <anton.kalyaev@gmail.com>

CHANGELOG_PENDING.md

@@ -113,6 +113,7 @@ program](https://hackerone.com/tendermint).
 - [cli] \#4234 Add `--db_backend and --db_dir` flags (@princesinha19)
 - [cli] \#4113 Add optional `--genesis_hash` flag to check genesis hash upon startup
 - [config] \#3831 Add support for [RocksDB](https://rocksdb.org/) (@Stumble)
+- [rpc] \#3985 Add new `/block_by_hash` endpoint, which allows to fetch a block by its hash (@princesinha19)
 - [metrics] \#4263 Add
   - `consensus_validator_power`: track your validators power
   - `consensus_validator_last_signed_height`: track at which height the validator last signed

consensus/replay_test.go

@@ -1062,6 +1062,9 @@ func newMockBlockStore(config *cfg.Config, params types.ConsensusParams) *mockBl
 
 func (bs *mockBlockStore) Height() int64                       { return int64(len(bs.chain)) }
 func (bs *mockBlockStore) LoadBlock(height int64) *types.Block { return bs.chain[height-1] }
+func (bs *mockBlockStore) LoadBlockByHash(hash []byte) *types.Block {
+	return bs.chain[int64(len(bs.chain))-1]
+}
 func (bs *mockBlockStore) LoadBlockMeta(height int64) *types.BlockMeta {
 	block := bs.chain[height-1]
 	return &types.BlockMeta{

rpc/core/blocks.go

@@ -81,6 +81,16 @@ func Block(ctx *rpctypes.Context, heightPtr *int64) (*ctypes.ResultBlock, error)
 	return &ctypes.ResultBlock{BlockID: blockMeta.BlockID, Block: block}, nil
 }
 
+// BlockByHash gets block by hash.
+// More: https://tendermint.com/rpc/#/Info/block_by_hash
+func BlockByHash(ctx *rpctypes.Context, hash []byte) (*ctypes.ResultBlock, error) {
+	block := blockStore.LoadBlockByHash(hash)
+	height := block.Height
+
+	blockMeta := blockStore.LoadBlockMeta(height)
+	return &ctypes.ResultBlock{BlockID: blockMeta.BlockID, Block: block}, nil
+}
+
 // Commit gets block commit at a given height.
 // If no height is provided, it will fetch the commit for the latest block.
 // More: https://tendermint.com/rpc/#/Info/commit

rpc/core/blocks_test.go

@@ -114,6 +114,7 @@ type mockBlockStore struct {
 func (store mockBlockStore) Height() int64                               { return store.height }
 func (mockBlockStore) LoadBlockMeta(height int64) *types.BlockMeta       { return nil }
 func (mockBlockStore) LoadBlock(height int64) *types.Block               { return nil }
+func (mockBlockStore) LoadBlockByHash(hash []byte) *types.Block          { return nil }
 func (mockBlockStore) LoadBlockPart(height int64, index int) *types.Part { return nil }
 func (mockBlockStore) LoadBlockCommit(height int64) *types.Commit        { return nil }
 func (mockBlockStore) LoadSeenCommit(height int64) *types.Commit         { return nil }

rpc/core/routes.go

@@ -19,6 +19,7 @@ var Routes = map[string]*rpc.RPCFunc{
 	"blockchain":           rpc.NewRPCFunc(BlockchainInfo, "minHeight,maxHeight"),
 	"genesis":              rpc.NewRPCFunc(Genesis, ""),
 	"block":                rpc.NewRPCFunc(Block, "height"),
+	"block_by_hash":        rpc.NewRPCFunc(BlockByHash, "hash"),
 	"block_results":        rpc.NewRPCFunc(BlockResults, "height"),
 	"commit":               rpc.NewRPCFunc(Commit, "height"),
 	"tx":                   rpc.NewRPCFunc(Tx, "hash,prove"),

rpc/swagger/swagger.yaml

@@ -550,6 +550,35 @@ paths:
             application/json:
               schema:
                 $ref: "#/components/schemas/ErrorResponse"
+  /block_by_hash:
+    get:
+      summary: Get block by hash
+      operationId: block_by_hash
+      parameters:
+        - in: query
+          name: hash
+          description: block hash
+          required: true
+          schema:
+            type: string
+            example: "0xD70952032620CC4E2737EB8AC379806359D8E0B17B0488F627997A0B043ABDED"
+      tags:
+        - Info
+      description: |
+        Get Block By Hash.
+      responses:
+        200:
+          description: Block informations.
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/BlockResponse"
+        500:
+          description: Error
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ErrorResponse"
   /block_results:
     get:
       summary: Get block results at a specified height

state/services.go

@@ -18,6 +18,7 @@ type BlockStoreRPC interface {
 
 	LoadBlockMeta(height int64) *types.BlockMeta
 	LoadBlock(height int64) *types.Block
+	LoadBlockByHash(hash []byte) *types.Block
 	LoadBlockPart(height int64, index int) *types.Part
 
 	LoadBlockCommit(height int64) *types.Commit

store/store.go

@@ -2,6 +2,7 @@ package store
 
 import (
 	"fmt"
+	"strconv"
 	"sync"
 
 	"github.com/pkg/errors"
@@ -73,6 +74,24 @@ func (bs *BlockStore) LoadBlock(height int64) *types.Block {
 	return block
 }
 
+// LoadBlockByHash returns the block with the given hash.
+// If no block is found for that hash, it returns nil.
+// Panics if it fails to parse height associated with the given hash.
+func (bs *BlockStore) LoadBlockByHash(hash []byte) *types.Block {
+	bz := bs.db.Get(calcBlockHashKey(hash))
+	if len(bz) == 0 {
+		return nil
+	}
+
+	s := string(bz)
+	height, err := strconv.ParseInt(s, 10, 64)
+
+	if err != nil {
+		panic(errors.Wrapf(err, "failed to extract height from %s", s))
+	}
+	return bs.LoadBlock(height)
+}
+
 // LoadBlockPart returns the Part at the given index
 // from the block at the given height.
 // If no part is found for the given height and index, it returns nil.
@@ -147,7 +166,10 @@ func (bs *BlockStore) SaveBlock(block *types.Block, blockParts *types.PartSet, s
 	if block == nil {
 		panic("BlockStore can only save a non-nil block")
 	}
+
 	height := block.Height
+	hash := block.Hash()
+
 	if g, w := height, bs.Height()+1; g != w {
 		panic(fmt.Sprintf("BlockStore can only save contiguous blocks. Wanted %v, got %v", w, g))
 	}
@@ -159,6 +181,7 @@ func (bs *BlockStore) SaveBlock(block *types.Block, blockParts *types.PartSet, s
 	blockMeta := types.NewBlockMeta(block, blockParts)
 	metaBytes := cdc.MustMarshalBinaryBare(blockMeta)
 	bs.db.Set(calcBlockMetaKey(height), metaBytes)
+	bs.db.Set(calcBlockHashKey(hash), []byte(fmt.Sprintf("%d", height)))
 
 	// Save block parts
 	for i := 0; i < blockParts.Total(); i++ {
@@ -213,6 +236,10 @@ func calcSeenCommitKey(height int64) []byte {
 	return []byte(fmt.Sprintf("SC:%v", height))
 }
 
+func calcBlockHashKey(hash []byte) []byte {
+	return []byte(fmt.Sprintf("BH:%x", hash))
+}
+
 //-----------------------------------------------------------------------------
 
 var blockStoreKey = []byte("blockStore")