Implement EIP-2935: Serve historical block hashes from state (#2606)

* Implement EIP-2935: Serve historical block hashes from state

* Fix EIP-2935 in t8n

nimbus/constants.nim

@@ -107,4 +107,5 @@ const
       result[19] = x.byte
     initAddress(3)
 
+  HISTORY_STORAGE_ADDRESS* = hexToByteArray[20]("0x0aae40965e6800cd9b1f4b05ff21581047e3f91e")
 # End

nimbus/core/executor/process_block.nim

@@ -66,6 +66,9 @@ proc procBlkPreamble(
     if blk.transactions.calcTxRoot != header.txRoot:
       return err("Mismatched txRoot")
 
+  if com.isPragueOrLater(header.timestamp):
+    ?vmState.processParentBlockHash(header.parentHash)
+
   if com.isCancunOrLater(header.timestamp):
     if header.parentBeaconBlockRoot.isNone:
       return err("Post-Cancun block header must have parentBeaconBlockRoot")
@@ -144,10 +147,10 @@ proc procBlkEpilogue(
 
     if not skipReceipts:
       let bloom = createBloom(vmState.receipts)
-  
+
       if header.logsBloom != bloom:
         return err("bloom mismatch")
-  
+
       let receiptsRoot = calcReceiptsRoot(vmState.receipts)
       if header.receiptsRoot != receiptsRoot:
         # TODO replace logging with better error

nimbus/core/executor/process_transaction.nim

@@ -157,6 +157,36 @@ proc processBeaconBlockRoot*(vmState: BaseVMState, beaconRoot: Hash256):
   statedb.persist(clearEmptyAccount = true)
   ok()
 
+proc processParentBlockHash*(vmState: BaseVMState, prevHash: Hash256):
+                              Result[void, string] =
+  ## processParentBlockHash stores the parent block hash in the 
+  ## history storage contract as per EIP-2935.
+  let
+    statedb = vmState.stateDB
+    call = CallParams(
+      vmState  : vmState,
+      sender   : SYSTEM_ADDRESS,
+      gasLimit : 30_000_000.GasInt,
+      gasPrice : 0.GasInt,
+      to       : HISTORY_STORAGE_ADDRESS,
+      input    : @(prevHash.data),
+
+      # It's a systemCall, no need for other knicks knacks
+      sysCall     : true,
+      noAccessList: true,
+      noIntrinsic : true,
+      noGasCharge : true,
+      noRefund    : true,
+    )
+
+  # runComputation a.k.a syscall/evm.call
+  let res = call.runComputation(string)
+  if res.len > 0:
+    return err("processParentBlockHash: " & res)
+
+  statedb.persist(clearEmptyAccount = true)
+  ok()
+  
 proc processTransaction*(
     vmState: BaseVMState; ## Parent accounts environment for transaction
     tx:      Transaction; ## Transaction to validate

tools/t8n/transition.nim

@@ -234,6 +234,18 @@ proc exec(ctx: var TransContext,
     vmState.processBeaconBlockRoot(ctx.env.parentBeaconBlockRoot.get).isOkOr:
       raise newError(ErrorConfig, error)
 
+  if vmState.com.isPragueOrLater(ctx.env.currentTimestamp) and
+     ctx.env.blockHashes.len > 0:
+    let
+      prevNumber = ctx.env.currentNumber - 1
+      prevHash = ctx.env.blockHashes.getOrDefault(prevNumber)
+
+    if prevHash == static(Hash256()):
+      raise newError(ErrorConfig, "previous block hash not found for block number: " & $prevNumber)
+
+    vmState.processParentBlockHash(prevHash).isOkOr:
+      raise newError(ErrorConfig, error)
+
   for txIndex, txRes in txList:
     if txRes.isErr:
       rejected.add RejectedTx(