EIP-1559: Fee market change for ETH 1.0 chain

Transaction and BlockHeader already updated in nim-eth repo
to support EIP-1559

EIP-1559 header validation and gasLimit validation
already implemented in previous commit

This commit deals with block validation:
- Effective gasPrice per EIP-1559
- new miner reward based on priorityFee

nimbus/chain_config.nim

@@ -68,6 +68,7 @@ type
     mixHash*    : Hash256
     coinbase*   : EthAddress
     alloc*      : GenesisAlloc
+    baseFeePerGas*: Option[UInt256]
     
   GenesisAlloc* = Table[EthAddress, GenesisAccount]
   GenesisAccount* = object

nimbus/genesis.nim

@@ -4,7 +4,7 @@ import
   chronicles, eth/trie/db,
   ./db/[db_chain, state_db],
   ./genesis_alloc, ./config, ./constants,
-  ./chain_config
+  ./chain_config, ./forks, ./p2p/gaslimit
 
 proc defaultGenesisBlockForNetwork*(id: NetworkId): Genesis =
   result = case id
@@ -74,6 +74,11 @@ proc toBlock*(g: Genesis, db: BaseChainDB = nil): BlockHeader =
     ommersHash: EMPTY_UNCLE_HASH
   )
 
+  if g.baseFeePerGas.isSome:
+    result.baseFee = g.baseFeePerGas.get()
+  elif db.isNil.not and db.config.toFork(0.toBlockNumber) >= FkLondon:
+    result.baseFee = EIP1559_INITIAL_BASE_FEE.u256
+
   if g.gasLimit == 0:
     result.gasLimit = GENESIS_GAS_LIMIT
 

nimbus/p2p/executor.nim

@@ -6,6 +6,11 @@ import options, sets,
   ./dao, ./validate, ../config, ../forks,
   ../transaction/call_evm
 
+proc eip1559TxNormalization(tx: Transaction): Transaction =
+  result = tx
+  if tx.txType < TxEip1559:
+    result.maxPriorityFee = tx.gasPrice
+    result.maxFee = tx.gasPrice
 
 proc processTransaction*(tx: Transaction, sender: EthAddress, vmState: BaseVMState, fork: Fork): GasInt =
   ## Process the transaction, write the results to db.
@@ -13,18 +18,33 @@ proc processTransaction*(tx: Transaction, sender: EthAddress, vmState: BaseVMSta
   trace "Sender", sender
   trace "txHash", rlpHash = tx.rlpHash
 
+  var tx = eip1559TxNormalization(tx)
+  var priorityFee: GasInt
+  if fork >= FkLondon:
+    # priority fee is capped because the base fee is filled first
+    let baseFee = vmState.blockHeader.baseFee.truncate(GasInt)
+    priorityFee = min(tx.maxPriorityFee, tx.maxFee - baseFee)
+    # signer pays both the priority fee and the base fee
+    # tx.gasPrice now is the effective gasPrice
+    tx.gasPrice = priorityFee + baseFee
+
+  let miner = vmState.coinbase()
   if validateTransaction(vmState, tx, sender, fork):
     result = txCallEvm(tx, sender, vmState, fork)
 
+    # miner fee
+    if fork >= FkLondon:
+      # miner only receives the priority fee;
+      # note that the base fee is not given to anyone (it is burned)
+      let txFee = result.u256 * priorityFee.u256
+      vmState.accountDb.addBalance(miner, txFee)
+    else:
+      let txFee = result.u256 * tx.gasPrice.u256
+      vmState.accountDb.addBalance(miner, txFee)
+
   vmState.cumulativeGasUsed += result
 
-  let miner = vmState.coinbase()
-
   vmState.mutateStateDB:
-    # miner fee
-    let txFee = result.u256 * tx.gasPrice.u256
-    db.addBalance(miner, txFee)
-
     for deletedAccount in vmState.selfDestructs:
       db.deleteAccount deletedAccount
 
@@ -145,6 +165,12 @@ proc processBlock*(chainDB: BaseChainDB, header: BlockHeader, body: BlockBody, v
           return ValidationResult.Error
         vmState.receipts[txIndex] = makeReceipt(vmState, fork, tx.txType)
 
+  if vmState.cumulativeGasUsed != header.gasUsed:
+    debug "gasUsed neq cumulativeGasUsed",
+      gasUsed=header.gasUsed,
+      cumulativeGasUsed=vmState.cumulativeGasUsed
+    return ValidationResult.Error
+
   if header.ommersHash != EMPTY_UNCLE_HASH:
     let h = chainDB.persistUncles(body.uncles)
     if h != header.ommersHash:

nimbus/p2p/validate.nim

@@ -259,6 +259,10 @@ proc validateUncles(chainDB: BaseChainDB; header: BlockHeader;
     if result.isErr:
       return
 
+    result = chainDB.validateGasLimitOrBaseFee(uncle, uncleParent)
+    if result.isErr:
+      return
+
   result = ok()
 
 # ------------------------------------------------------------------------------
@@ -270,6 +274,14 @@ proc validateTransaction*(vmState: BaseVMState, tx: Transaction,
   let balance = vmState.readOnlyStateDB.getBalance(sender)
   let nonce = vmState.readOnlyStateDB.getNonce(sender)
 
+  if tx.txType == TxEip2930 and fork < FkBerlin:
+    debug "invalid tx: Eip2930 Tx type detected before Berlin"
+    return
+
+  if tx.txType == TxEip1559 and fork < FkLondon:
+    debug "invalid tx: Eip1559 Tx type detected before London"
+    return
+
   if vmState.cumulativeGasUsed + tx.gasLimit > vmState.blockHeader.gasLimit:
     debug "invalid tx: block header gasLimit reached",
       maxLimit=vmState.blockHeader.gasLimit,
@@ -277,6 +289,21 @@ proc validateTransaction*(vmState: BaseVMState, tx: Transaction,
       addition=tx.gasLimit
     return
 
+  # ensure that the user was willing to at least pay the base fee
+  let baseFee = vmState.blockHeader.baseFee.truncate(GasInt)
+  if tx.maxFee < baseFee:
+    debug "invalid tx: maxFee is smaller than baseFee",
+      maxFee=tx.maxFee,
+      baseFee=baseFee
+    return
+
+  # The total must be the larger of the two
+  if tx.maxFee < tx.maxPriorityFee:
+    debug "invalid tx: maxFee is smaller than maPriorityFee",
+      maxFee=tx.maxFee,
+      maxPriorityFee=tx.maxPriorityFee
+    return
+
   let gasCost = tx.gasLimit.u256 * tx.gasPrice.u256
   if gasCost > balance:
     debug "invalid tx: not enough cash for gas",

nimbus/utils/header.nim

@@ -59,7 +59,7 @@ proc computeGasLimit*(parent: BlockHeader, gasLimitFloor: GasInt): GasInt =
 
 proc generateHeaderFromParentHeader*(config: ChainConfig, parent: BlockHeader,
     coinbase: EthAddress, timestamp: Option[EthTime],
-    gasLimit: Option[GasInt], extraData: Blob): BlockHeader =
+    gasLimit: Option[GasInt], extraData: Blob, baseFee: Option[Uint256]): BlockHeader =
 
   var lcTimestamp: EthTime
   if timestamp.isNone:
@@ -78,4 +78,5 @@ proc generateHeaderFromParentHeader*(config: ChainConfig, parent: BlockHeader,
     stateRoot: parent.stateRoot,
     coinbase: coinbase,
     extraData: extraData,
+    fee: baseFee
   )

nimbus/vm/evmc_host.nim

@@ -18,6 +18,7 @@ proc hostGetTxContextImpl(ctx: Computation): nimbus_tx_context {.cdecl.} =
   result.block_gas_limit = int64(vmstate.blockHeader.gasLimit)
   result.block_difficulty = toEvmc(vmstate.difficulty)
   result.chain_id = toEvmc(vmstate.chaindb.config.chainId.uint.u256)
+  result.block_base_fee = toEvmc(vmstate.blockHeader.baseFee)
 
 proc hostGetBlockHashImpl(ctx: Computation, number: int64): Hash256 {.cdecl.} =
   ctx.vmState.getAncestorHash(number.u256)

nimbus/vm_state.nim

@@ -32,6 +32,7 @@ export
   vms.disableTracing,
   vms.enableTracing,
   vms.gasLimit,
+  vms.baseFee,
   vms.generateWitness,
   vms.`generateWitness=`,
   vms.getAncestorHash,