Handle blocks from cache (#1312)

* Handle blocks from cache

lc_proxy/block_cache.nim

@@ -60,3 +60,8 @@ proc getByNumber*(
       break
 
   return payloadResult
+
+proc getPayloadByHash*(
+    self: BlockCache,
+    hash: BlockHash): Opt[ExecutionPayloadV1] =
+  return self.blocks.eq(hash)

lc_proxy/rpc/rpc_eth_lc_api.nim

@@ -19,6 +19,7 @@ import
   beacon_chain/eth1/eth1_monitor,
   beacon_chain/networking/network_metadata,
   beacon_chain/spec/forks,
+  ./rpc_utils,
   ../validate_proof,
   ../block_cache
 
@@ -88,7 +89,7 @@ template rpcClient(lcProxy: LightClientRpcProxy): RpcClient = lcProxy.proxy.getC
 
 proc getPayloadByTag(
     proxy: LightClientRpcProxy,
-    quantityTag: string): ExecutionPayloadV1 {.raises: [ValueError, Defect].} =
+    quantityTag: string): results.Opt[ExecutionPayloadV1] {.raises: [ValueError, Defect].} =
   checkPreconditions(proxy)
 
   let tagResult = parseQuantityTag(quantityTag)
@@ -98,25 +99,25 @@ proc getPayloadByTag(
 
   let tag = tagResult.get()
 
-  var payload: ExecutionPayloadV1
-
   case tag.kind
   of LatestBlock:
-    # this will always be ok as we always validate that cache is not empty
-    payload = proxy.blockCache.latest.get
+    # this will always return some block, as we always checkPreconditions
+    return proxy.blockCache.latest
   of BlockNumber:
-    let payLoadResult = proxy.blockCache.getByNumber(tag.blockNumber)
-    if payLoadResult.isErr():
-      raise newException(
-        ValueError, "Block not stored in cache " & $tag.blockNumber
-      )
-    payload = payLoadResult.get
+    return proxy.blockCache.getByNumber(tag.blockNumber)
 
-  return payload
+proc getPayloadByTagOrThrow(
+    proxy: LightClientRpcProxy,
+    quantityTag: string): ExecutionPayloadV1 {.raises: [ValueError, Defect].} =
+
+  let tagResult = getPayloadByTag(proxy, quantityTag)
+
+  if tagResult.isErr:
+    raise newException(ValueError, "No block stored for given tag " & quantityTag)
+
+  return tagResult.get()
 
 proc installEthApiHandlers*(lcProxy: LightClientRpcProxy) =
-  template payload(): Opt[ExecutionPayloadV1] = lcProxy.executionPayload
-
   lcProxy.proxy.rpc("eth_chainId") do() -> HexQuantityStr:
     return encodeQuantity(lcProxy.chainId)
 
@@ -132,7 +133,7 @@ proc installEthApiHandlers*(lcProxy: LightClientRpcProxy) =
     # can mean different blocks and ultimatly piece received piece of state
     # must by validated against correct state root
     let
-      executionPayload = lcProxy.getPayloadByTag(quantityTag)
+      executionPayload = lcProxy.getPayloadByTagOrThrow(quantityTag)
       blockNumber = executionPayload.blockNumber.uint64
 
     info "Forwarding get_Balance", executionBn = blockNumber
@@ -156,7 +157,7 @@ proc installEthApiHandlers*(lcProxy: LightClientRpcProxy) =
 
   lcProxy.proxy.rpc("eth_getStorageAt") do(address: Address, slot: HexDataStr, quantityTag: string) -> HexDataStr:
     let
-      executionPayload = lcProxy.getPayloadByTag(quantityTag)
+      executionPayload = lcProxy.getPayloadByTagOrThrow(quantityTag)
       uslot = UInt256.fromHex(slot.string)
       blockNumber = executionPayload.blockNumber.uint64
 
@@ -174,7 +175,7 @@ proc installEthApiHandlers*(lcProxy: LightClientRpcProxy) =
 
   lcProxy.proxy.rpc("eth_getTransactionCount") do(address: Address, quantityTag: string) -> HexQuantityStr:
     let
-      executionPayload = lcProxy.getPayloadByTag(quantityTag)
+      executionPayload = lcProxy.getPayloadByTagOrThrow(quantityTag)
       blockNumber = executionPayload.blockNumber.uint64
 
     info "Forwarding eth_getTransactionCount", executionBn = blockNumber
@@ -198,7 +199,7 @@ proc installEthApiHandlers*(lcProxy: LightClientRpcProxy) =
 
   lcProxy.proxy.rpc("eth_getCode") do(address: Address, quantityTag: string) -> HexDataStr:
     let
-      executionPayload = lcProxy.getPayloadByTag(quantityTag)
+      executionPayload = lcProxy.getPayloadByTagOrThrow(quantityTag)
       blockNumber = executionPayload.blockNumber.uint64
 
     let
@@ -239,9 +240,23 @@ proc installEthApiHandlers*(lcProxy: LightClientRpcProxy) =
   lcProxy.proxy.registerProxyMethod("eth_sendRawTransaction")
   lcProxy.proxy.registerProxyMethod("eth_getTransactionReceipt")
 
-  # TODO Respond to this calls using BlockCache
-  lcProxy.proxy.registerProxyMethod("eth_getBlockByNumber")
-  lcProxy.proxy.registerProxyMethod("eth_getBlockByHash")
+  # TODO currently we do not handle fullTransactions flag. It require updates on
+  # nim-web3 side
+  lcProxy.proxy.rpc("eth_getBlockByNumber") do(quantityTag: string, fullTransactions: bool) -> Option[BlockObject]:
+    let executionPayload = lcProxy.getPayloadByTag(quantityTag)
+
+    if executionPayload.isErr:
+      return none(BlockObject)
+
+    return some(asBlockObject(executionPayload.get()))
+
+  lcProxy.proxy.rpc("eth_getBlockByHash") do(blockHash: BlockHash, fullTransactions: bool) -> Option[BlockObject]:
+    let executionPayload = lcProxy.blockCache.getPayloadByHash(blockHash)
+
+    if executionPayload.isErr:
+      return none(BlockObject)
+
+    return some(asBlockObject(executionPayload.get()))
 
 proc new*(
     T: type LightClientRpcProxy,

lc_proxy/rpc/rpc_utils.nim

@@ -0,0 +1,86 @@
+import
+  std/typetraits,
+  eth/common/eth_types as etypes,
+  eth/[trie, rlp, trie/db],
+  stint,
+  web3
+
+template unsafeQuantityToInt64(q: Quantity): int64 =
+  int64 q
+
+func toFixedBytes(d: MDigest[256]): FixedBytes[32] =
+  FixedBytes[32](d.data)
+
+template asEthHash(hash: BlockHash): Hash256 =
+  Hash256(data: distinctBase(hash))
+
+proc calculateTransactionData(
+  items: openArray[TypedTransaction]): (etypes.Hash256, seq[TxHash], uint64) =
+  ## returns tuple composed of
+  ## - root of transactions trie
+  ## - list of transactions hashes
+  ## - total size of transactions in block
+  var tr = initHexaryTrie(newMemoryDB())
+  var txHashes: seq[TxHash]
+  var txSize: uint64
+  for i, t in items:
+    let tx = distinctBase(t)
+    txSize = txSize + uint64(len(tx))
+    tr.put(rlp.encode(i), tx)
+    txHashes.add(toFixedBytes(keccakHash(tx)))
+  return (tr.rootHash(), txHashes, txSize)
+
+func blockHeaderSize(payload: ExecutionPayloadV1, txRoot: etypes.Hash256): uint64 =
+  let bh = etypes.BlockHeader(
+    parentHash    : payload.parentHash.asEthHash,
+    ommersHash    : etypes.EMPTY_UNCLE_HASH,
+    coinbase      : etypes.EthAddress payload.feeRecipient,
+    stateRoot     : payload.stateRoot.asEthHash,
+    txRoot        : txRoot,
+    receiptRoot   : payload.receiptsRoot.asEthHash,
+    bloom         : distinctBase(payload.logsBloom),
+    difficulty    : default(etypes.DifficultyInt),
+    blockNumber   : payload.blockNumber.distinctBase.u256,
+    gasLimit      : payload.gasLimit.unsafeQuantityToInt64,
+    gasUsed       : payload.gasUsed.unsafeQuantityToInt64,
+    timestamp     : fromUnix payload.timestamp.unsafeQuantityToInt64,
+    extraData     : bytes payload.extraData,
+    mixDigest     : payload.prevRandao.asEthHash,
+    nonce         : default(etypes.BlockNonce),
+    fee           : some payload.baseFeePerGas
+  )
+  return uint64(len(rlp.encode(bh)))
+
+proc asBlockObject*(p: ExecutionPayloadV1): BlockObject =
+  # TODO currently we always calculate txHashes as BlockObject does not have
+  # option of returning full transactions. It needs fixing at nim-web3 library
+  # level
+  let (txRoot, txHashes, txSize) = calculateTransactionData(p.transactions)
+  let headerSize = blockHeaderSize(p, txRoot)
+  let blockSize = txSize + headerSize
+  BlockObject(
+    number: p.blockNumber,
+    hash: p.blockHash,
+    parentHash: p.parentHash,
+    sha3Uncles: FixedBytes(etypes.EMPTY_UNCLE_HASH.data),
+    logsBloom: p.logsBloom,
+    transactionsRoot: toFixedBytes(txRoot),
+    stateRoot: p.stateRoot,
+    receiptsRoot: p.receiptsRoot,
+    miner: p.feeRecipient,
+    difficulty: UInt256.zero,
+    extraData: p.extraData.toHex,
+    gasLimit: p.gasLimit,
+    gasUsed: p.gasUsed,
+    timestamp: p.timestamp,
+    nonce: some(default(FixedBytes[8])),
+    size: Quantity(blockSize),
+    # TODO It does not matter what we put here in after merge blocks.
+    # Other projects like `helios` return `0`, data providers like alchemy return
+    # transition difficulty. For now retruning `0` as this is a bit easier to do.
+    totalDifficulty: UInt256.zero,
+    transactions: txHashes,
+    uncles: @[],
+    baseFeePerGas: some(p.baseFeePerGas)
+  )
+