From 2385df7baebb1637b95a1e99118d94325f739001 Mon Sep 17 00:00:00 2001
From: jangko <jangko128@gmail.com>
Date: Fri, 19 Jun 2020 20:24:09 +0700
Subject: [PATCH] miner address calculation for PoA consensus engine

---
 nimbus/p2p/executor.nim | 38 ++++++++++++++++++++++------------
 nimbus/vm_state.nim     | 46 +++++++++++++++++++++++++++++++++++++++--
 2 files changed, 69 insertions(+), 15 deletions(-)

diff --git a/nimbus/p2p/executor.nim b/nimbus/p2p/executor.nim
index 2b0cc6a3b..095852da7 100644
--- a/nimbus/p2p/executor.nim
+++ b/nimbus/p2p/executor.nim
@@ -26,16 +26,18 @@ proc processTransaction*(tx: Transaction, sender: EthAddress, vmState: BaseVMSta
 
   vmState.cumulativeGasUsed += result
 
+  let miner = vmState.getMinerAddress()
+
   vmState.mutateStateDB:
     # miner fee
     let txFee = result.u256 * tx.gasPrice.u256
-    db.addBalance(vmState.blockHeader.coinbase, txFee)
+    db.addBalance(miner, txFee)
 
     for deletedAccount in vmState.suicides:
       db.deleteAccount deletedAccount
 
     if fork >= FkSpurious:
-      vmState.touchedAccounts.incl(vmState.blockHeader.coinbase)
+      vmState.touchedAccounts.incl(miner)
       # EIP158/161 state clearing
       for account in vmState.touchedAccounts:
         if db.accountExists(account) and db.isEmptyAccount(account):
@@ -93,6 +95,25 @@ const
     eth2  # FkIstanbul
   ]
 
+proc calculateReward(fork: Fork, header: BlockHeader, body: BlockBody, vmState: BaseVMState) =
+  # PoA consensus engine have no reward for miner
+  if vmState.consensusEnginePoA: return
+
+  let blockReward = blockRewards[fork]
+  var mainReward = blockReward
+
+  for uncle in body.uncles:
+    var uncleReward = uncle.blockNumber.u256 + 8.u256
+    uncleReward -= header.blockNumber.u256
+    uncleReward = uncleReward * blockReward
+    uncleReward = uncleReward div 8.u256
+    vmState.mutateStateDB:
+      db.addBalance(uncle.coinbase, uncleReward)
+    mainReward += blockReward div 32.u256
+
+  vmState.mutateStateDB:
+    db.addBalance(header.coinbase, mainReward)
+
 proc processBlock*(chainDB: BaseChainDB, header: BlockHeader, body: BlockBody, vmState: BaseVMState): ValidationResult =
   var dbTx = chainDB.db.beginTransaction()
   defer: dbTx.dispose()
@@ -125,25 +146,16 @@ proc processBlock*(chainDB: BaseChainDB, header: BlockHeader, body: BlockBody, v
           return ValidationResult.Error
         vmState.receipts[txIndex] = makeReceipt(vmState, fork)
 
-  let blockReward = blockRewards[fork]
-  var mainReward = blockReward
   if header.ommersHash != EMPTY_UNCLE_HASH:
     let h = chainDB.persistUncles(body.uncles)
     if h != header.ommersHash:
       debug "Uncle hash mismatch"
       return ValidationResult.Error
-    for uncle in body.uncles:
-      var uncleReward = uncle.blockNumber.u256 + 8.u256
-      uncleReward -= header.blockNumber.u256
-      uncleReward = uncleReward * blockReward
-      uncleReward = uncleReward div 8.u256
-      vmState.mutateStateDB:
-        db.addBalance(uncle.coinbase, uncleReward)
-      mainReward += blockReward div 32.u256
+
+  calculateReward(fork, header, body, vmState)
 
   # Reward beneficiary
   vmState.mutateStateDB:
-    db.addBalance(header.coinbase, mainReward)
     if vmState.generateWitness:
       db.collectWitnessData()
     db.persist(ClearCache in vmState.flags)
diff --git a/nimbus/vm_state.nim b/nimbus/vm_state.nim
index f59d02b1b..2f99fa45a 100644
--- a/nimbus/vm_state.nim
+++ b/nimbus/vm_state.nim
@@ -7,8 +7,8 @@
 
 import
   macros, strformat, tables, sets, options,
-  eth/common,
-  vm/interpreter/[vm_forks, gas_costs],
+  eth/[common, keys, rlp], nimcrypto/keccak,
+  vm/interpreter/[vm_forks, gas_costs], ./errors,
   ./constants, ./db/[db_chain, accounts_cache],
   ./utils, json, vm_types, vm/transaction_tracer,
   ./config, ../stateless/[multi_keys, witness_from_tree, witness_types]
@@ -61,6 +61,48 @@ proc setupTxContext*(vmState: BaseVMState, origin: EthAddress, gasPrice: GasInt,
       vmState.chainDB.config.toFork(vmState.blockHeader.blockNumber)
   vmState.gasCosts = vmState.fork.forkToSchedule
 
+proc consensusEnginePoA*(vmState: BaseVMState): bool =
+  let chainId = PublicNetwork(vmState.chainDB.config.chainId)
+  # PoA consensus engine have no reward for miner
+  result = chainId in {GoerliNet, RinkebyNet, KovanNet}
+
+proc getSignature(bytes: openArray[byte], output: var Signature): bool =
+  let sig = Signature.fromRaw(bytes)
+  if sig.isOk:
+    output = sig[]
+    return true
+  return false
+
+proc headerHashOriExtraData(vmState: BaseVMState): Hash256 =
+  var tmp = vmState.blockHeader
+  tmp.extraData.setLen(tmp.extraData.len-65)
+  result = keccak256.digest(rlp.encode(tmp))
+
+proc getPubkey(sigRaw: openArray[byte], vmState: BaseVMState, output: var EthAddress): bool =
+  var sig: Signature
+  if sigRaw.getSignature(sig):
+    let headerHash = headerHashOriExtraData(vmState)
+    let pubkey = recover(sig, headerHash)
+    if pubkey.isOk:
+      output = pubkey[].toCanonicalAddress()
+      result = true
+
+proc getMinerAddress*(vmState: BaseVMState): EthAddress =
+  if not vmState.consensusEnginePoA:
+    return vmState.blockHeader.coinbase
+
+  template data: untyped =
+    vmState.blockHeader.extraData
+
+  let len = data.len
+  doAssert(len >= 65)
+
+  var miner: EthAddress
+  if getPubkey(data.toOpenArray(len - 65, len-1), vmState, miner):
+    result = miner
+  else:
+    raise newException(ValidationError, "Could not derive miner address from header extradata")
+
 proc updateBlockHeader*(vmState: BaseVMState, header: BlockHeader) =
   vmState.blockHeader = header
   vmState.touchedAccounts.clear()