EIP-1559: unify PoA and PoW gasLimit and baseFee validation

Turn out both EthHash and Clique are using the same gasLimit
validation.

They also share the same EIP-1559 baseFee validation.

nimbus/p2p/clique.nim

@@ -24,6 +24,7 @@ import
   ../db/[db_chain, state_db],
   ../utils,
   ./clique/[clique_cfg, clique_defs, clique_utils, ec_recover, recent_snaps],
+  ./gaslimit,
   chronicles,
   chronos,
   eth/[common, keys, rlp],
@@ -190,20 +191,9 @@ proc verifyCascadingFields(c: var Clique; header: BlockHeader;
                 &"invalid gasUsed: have {header.gasUsed}, " &
                 &"gasLimit {header.gasLimit}"))
 
-  if not c.cfg.dbChain.config.isLondonOrLater(header.blockNumber):
+  let rc = c.cfg.dbChain.validateGasLimitOrBaseFee(header, parent)
-    # Verify BaseFee not present before EIP-1559 fork.
-    if not header.baseFee.isZero:
-      return err((errCliqueUnsupportedBaseFee,
-                  "invalid baseFee before London fork: have " &
-                  &"{header.baseFee}, want <0>"))
-    let rc = c.cfg.dbChain.validateGasLimit(header)
   if rc.isErr:
-      return err(rc.error)
+    return err((errCliqueGasLimitOrBaseFee, rc.error))
-  else:
-    let rc = c.cfg.dbChain.config.verify1559Header(parent = parent,
-                                                   header = header)
-    if rc.isErr:
-      return err(rc.error)
 
   # Retrieve the snapshot needed to verify this header and cache it
   var snap = c.snapshot(header.blockNumber-1, header.parentHash, parents)

nimbus/p2p/clique/clique_defs.nim

@@ -97,21 +97,6 @@ const
     ## the cutoff threshold and by clique as the snapshot trust limit.
     90000
 
-  # params/protocol_params.go(121): BaseFeeChangeDenominator = 8 [..]
-  EIP1559_BASE_FEE_CHANGE_DENOMINATOR* = ##\
-    ## Bounds the amount the base fee can change between blocks.
-    8
-
-  # params/protocol_params.go(122): ElasticityMultiplier = 2  [..]
-  EIP1559_ELASTICITY_MULTIPLIER* = ##\
-    ## Bounds the maximum gas limit an EIP-1559 block may have.
-    2
-
-  # params/protocol_params.go(123): InitialBaseFee = 1000000000 [..]
-  EIP1559_INITIAL_BASE_FEE* = ##\
-    ## Initial base fee for Eip1559 blocks.
-    1000000000.u256
-
 # ------------------------------------------------------------------------------
 # Error tokens
 # ------------------------------------------------------------------------------
@@ -244,16 +229,12 @@ type
     errSnapshotStore              ## ..
     errSnapshotClone
 
+    errCliqueGasLimitOrBaseFee
     errCliqueExceedsGasLimit
-    errCliqueUnsupportedBaseFee
-    errCliqueBaseFeeError
     errCliqueGasRepriceFork
     errCliqueSealSigFn
 
     errCliqueStopped = "process was interrupted"
-    errCliqueExpectedBaseFee = "header is missing baseFee"
-    errCliqueGasLimitTooLow = "gas limit is too low"
-    errCliqueGasLimitTooHigh = "gas limit is too high"
     errCliqueUnclesNotAllowed = "uncles not allowed"
 
     # not really an error

nimbus/p2p/clique/clique_utils.nim

@@ -45,24 +45,6 @@ type
 # Private helpers
 # ------------------------------------------------------------------------------
 
-proc gasLimitBounds(limit: GasInt): (GasInt, GasInt) =
-  ## See also utils.header.gasLimitBounds()
-  let
-    bndRange = limit div GAS_LIMIT_ADJUSTMENT_FACTOR
-    upperBound = if GAS_LIMIT_MAXIMUM - bndRange < limit: GAS_LIMIT_MAXIMUM
-                 else: limit + bndRange
-    lowerBound = max(GAS_LIMIT_MINIMUM, limit - bndRange)
-
-  return (lowerBound, upperBound)
-
-proc validateGasLimit(header: BlockHeader; limit: GasInt): CliqueResult =
-  let (lowBound, highBound) = gasLimitBounds(limit)
-  if header.gasLimit < lowBound:
-    return err((errCliqueGasLimitTooLow,""))
-  if highBound < header.gasLimit:
-    return err((errCliqueGasLimitTooHigh,""))
-  return ok()
-
 func zeroItem[T](t: typedesc[T]): T {.inline.} =
   discard
 
@@ -139,90 +121,6 @@ proc verifyForkHashes*(c: var ChainConfig; header: BlockHeader): CliqueResult {.
   return err((errCliqueGasRepriceFork,
               &"Homestead gas reprice fork: have {c.eip150Hash}, want {hash}"))
 
-proc validateGasLimit*(c: var BaseChainDB; header: BlockHeader): CliqueResult {.
-                       gcsafe, raises: [Defect,RlpError,BlockNotFound].} =
-  ## See also private function p2p.validate.validateGasLimit()
-  let parent = c.getBlockHeader(header.parentHash)
-  header.validateGasLimit(parent.gasLimit)
-
-# ------------------------------------------------------------------------------
-# Eip 1559 support
-# ------------------------------------------------------------------------------
-
-# params/config.go(450): func (c *ChainConfig) IsLondon(num [..]
-proc isLondonOrLater*(c: var ChainConfig; number: BlockNumber): bool =
-  c.toFork(number) >= FkLondon
-
-# consensus/misc/eip1559.go(55): func CalcBaseFee(config [..]
-proc calc1599BaseFee*(c: var ChainConfig; parent: BlockHeader): UInt256 =
-  ## calculates the basefee of the header.
-
-  # If the current block is the first EIP-1559 block, return the
-  # initial base fee.
-  if not c.isLondonOrLater(parent.blockNumber):
-    return EIP1559_INITIAL_BASE_FEE
-
-  let parentGasTarget = parent.gasLimit div EIP1559_ELASTICITY_MULTIPLIER
-
-  # If the parent gasUsed is the same as the target, the baseFee remains
-  # unchanged.
-  if parent.gasUsed == parentGasTarget:
-    return parent.baseFee
-
-  let parentGasDenom = parentGasTarget.u256 *
-                         EIP1559_BASE_FEE_CHANGE_DENOMINATOR.u256
-
-  # baseFee is an Option[T]
-  let parentBaseFee  = parent.baseFee
-
-  if parentGasTarget < parent.gasUsed:
-    # If the parent block used more gas than its target, the baseFee should
-    # increase.
-    let
-      gasUsedDelta = (parent.gasUsed - parentGasTarget).u256
-      baseFeeDelta = (parentBaseFee * gasUsedDelta) div parentGasDenom
-
-    return parentBaseFee + max(baseFeeDelta, 1.u256)
-
-  else:
-    # Otherwise if the parent block used less gas than its target, the
-    # baseFee should decrease.
-    let
-      gasUsedDelta = (parentGasTarget - parent.gasUsed).u256
-      baseFeeDelta = (parentBaseFee * gasUsedDelta) div parentGasDenom
-
-    return max(parentBaseFee - baseFeeDelta, 0.u256)
-
-
-# consensus/misc/eip1559.go(32): func VerifyEip1559Header(config [..]
-proc verify1559Header*(c: var ChainConfig;
-                       parent, header: BlockHeader): CliqueResult {.
-                         gcsafe, raises: [Defect,ValueError].} =
-  ## Verify that the gas limit remains within allowed bounds
-  let limit = if c.isLondonOrLater(parent.blockNumber):
-                parent.gasLimit
-              else:
-                parent.gasLimit * EIP1559_ELASTICITY_MULTIPLIER
-  let rc = header.validateGasLimit(limit)
-  if rc.isErr:
-    return err(rc.error)
-
-  let headerBaseFee = header.baseFee
-  # Verify the header is not malformed
-  if headerBaseFee.isZero:
-    return err((errCliqueExpectedBaseFee,""))
-
-  # Verify the baseFee is correct based on the parent header.
-  var expectedBaseFee = c.calc1599BaseFee(parent)
-  if headerBaseFee != expectedBaseFee:
-    return err((errCliqueBaseFeeError,
-                &"invalid baseFee: have {expectedBaseFee}, "&
-                &"want {header.baseFee}, " &
-                &"parent.baseFee {parent.baseFee}, "&
-                &"parent.gasUsed {parent.gasUsed}"))
-
-  return ok()
-
 # ------------------------------------------------------------------------------
 # Seal hash support
 # ------------------------------------------------------------------------------

nimbus/p2p/gaslimit.nim

@@ -0,0 +1,153 @@
+# Nimbus
+# Copyright (c) 2018 Status Research & Development GmbH
+# Licensed under either of
+#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
+#    http://www.apache.org/licenses/LICENSE-2.0)
+#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or
+#    http://opensource.org/licenses/MIT)
+# at your option. This file may not be copied, modified, or distributed except
+# according to those terms.
+
+import
+  std/strformat,
+  stew/results,
+  eth/common,
+  ../db/db_chain,
+  ../constants,
+  ../errors,
+  ../chain_config,
+  ../forks,
+  ../config
+
+const
+  EIP1559_BASE_FEE_CHANGE_DENOMINATOR* = ##\
+    ## Bounds the amount the base fee can change between blocks.
+    8
+
+  EIP1559_ELASTICITY_MULTIPLIER* = ##\
+    ## Bounds the maximum gas limit an EIP-1559 block may have.
+    2
+
+  EIP1559_INITIAL_BASE_FEE* = ##\
+    ## Initial base fee for Eip1559 blocks.
+    1000000000.u256
+
+# ------------------------------------------------------------------------------
+# Pre Eip 1559 gas limit validation
+# ------------------------------------------------------------------------------
+
+proc validateGasLimit(header: BlockHeader; limit: GasInt): Result[void, string] =
+  let diff = if limit > header.gasLimit:
+               limit - header.gasLimit
+             else:
+               header.gasLimit - limit
+
+  let upperLimit = limit div GAS_LIMIT_ADJUSTMENT_FACTOR
+
+  if diff >= upperLimit:
+    return err("invalid gas limit: have {header.gasLimit}, want {limit} +-= {upperLimit-1}")
+  if header.gasLimit < GAS_LIMIT_MINIMUM:
+    return err("invalid gas limit below 5000")
+  ok()
+
+proc validateGasLimit(c: BaseChainDB; header: BlockHeader): Result[void, string] {.
+                       gcsafe, raises: [Defect,RlpError,BlockNotFound].} =
+  let parent = c.getBlockHeader(header.parentHash)
+  header.validateGasLimit(parent.gasLimit)
+
+# ------------------------------------------------------------------------------
+# Eip 1559 support
+# ------------------------------------------------------------------------------
+
+# params/config.go(450): func (c *ChainConfig) IsLondon(num [..]
+proc isLondonOrLater*(c: ChainConfig; number: BlockNumber): bool =
+  c.toFork(number) >= FkLondon
+
+# consensus/misc/eip1559.go(55): func CalcBaseFee(config [..]
+proc calcEip1599BaseFee(c: ChainConfig; parent: BlockHeader): UInt256 =
+  ## calculates the basefee of the header.
+
+  # If the current block is the first EIP-1559 block, return the
+  # initial base fee.
+  if not c.isLondonOrLater(parent.blockNumber):
+    return EIP1559_INITIAL_BASE_FEE
+
+  let parentGasTarget = parent.gasLimit div EIP1559_ELASTICITY_MULTIPLIER
+
+  # If the parent gasUsed is the same as the target, the baseFee remains
+  # unchanged.
+  if parent.gasUsed == parentGasTarget:
+    return parent.baseFee
+
+  let parentGasDenom = parentGasTarget.u256 *
+                         EIP1559_BASE_FEE_CHANGE_DENOMINATOR.u256
+
+  # baseFee is an Option[T]
+  let parentBaseFee  = parent.baseFee
+
+  if parentGasTarget < parent.gasUsed:
+    # If the parent block used more gas than its target, the baseFee should
+    # increase.
+    let
+      gasUsedDelta = (parent.gasUsed - parentGasTarget).u256
+      baseFeeDelta = (parentBaseFee * gasUsedDelta) div parentGasDenom
+
+    return parentBaseFee + max(baseFeeDelta, 1.u256)
+
+  else:
+    # Otherwise if the parent block used less gas than its target, the
+    # baseFee should decrease.
+    let
+      gasUsedDelta = (parentGasTarget - parent.gasUsed).u256
+      baseFeeDelta = (parentBaseFee * gasUsedDelta) div parentGasDenom
+
+    return max(parentBaseFee - baseFeeDelta, 0.u256)
+
+
+# consensus/misc/eip1559.go(32): func VerifyEip1559Header(config [..]
+proc verifyEip1559Header(c: ChainConfig;
+                       parent, header: BlockHeader): Result[void, string] {.
+                         gcsafe, raises: [Defect,ValueError].} =
+  ## Verify that the gas limit remains within allowed bounds
+  let limit = if c.isLondonOrLater(parent.blockNumber):
+                parent.gasLimit
+              else:
+                parent.gasLimit * EIP1559_ELASTICITY_MULTIPLIER
+  let rc = header.validateGasLimit(limit)
+  if rc.isErr:
+    return rc
+
+  let headerBaseFee = header.baseFee
+  # Verify the header is not malformed
+  if headerBaseFee.isZero:
+    return err("Post EIP-1559 header expected to have base fee")
+
+  # Verify the baseFee is correct based on the parent header.
+  var expectedBaseFee = c.calcEip1599BaseFee(parent)
+  if headerBaseFee != expectedBaseFee:
+    return err(&"invalid baseFee: have {expectedBaseFee}, "&
+               &"want {header.baseFee}, " &
+               &"parent.baseFee {parent.baseFee}, "&
+               &"parent.gasUsed {parent.gasUsed}")
+
+  return ok()
+
+proc validateGasLimitOrBaseFee*(c: BaseChainDB;
+                                header, parent: BlockHeader): Result[void, string] {.
+                                gcsafe, raises: [Defect,ValueError,CatchableError].} =
+
+  if not c.config.isLondonOrLater(header.blockNumber):
+    # Verify BaseFee not present before EIP-1559 fork.
+    if not header.baseFee.isZero:
+      return err("invalid baseFee before London fork: have " &
+                  &"{header.baseFee}, want <0>")
+    let rc = c.validateGasLimit(header)
+    if rc.isErr:
+      return rc
+  else:
+    let rc = c.config.verifyEip1559Header(parent = parent,
+                                          header = header)
+    if rc.isErr:
+      return rc
+
+  return ok()

nimbus/p2p/validate.nim

@@ -20,6 +20,7 @@ import
   ../forks,
   ./dao,
   ./validate/epoch_hash_cache,
+  ./gaslimit,
   chronicles,
   eth/[common, rlp, trie/trie_defs],
   ethash,
@@ -141,42 +142,12 @@ proc validateSeal(hashCache: var EpochHashCache;
   checkPOW(header.blockNumber, miningHash,
            header.mixDigest, header.nonce, header.difficulty, hashCache)
 
-
-proc validateGasLimit(chainDB: BaseChainDB;
-                      header: BlockHeader): Result[void,string] =
-  let parentHeader = chainDB.getBlockHeader(header.parentHash)
-  let (lowBound, highBound) = gasLimitBounds(parentHeader)
-
-  if header.gasLimit < lowBound:
-    return err("The gas limit is too low")
-  if header.gasLimit > highBound:
-    return err("The gas limit is too high")
-
-  result = ok()
-
-
-func validateGasLimit(gasLimit, parentGasLimit: GasInt): Result[void,string] =
-  if gasLimit < GAS_LIMIT_MINIMUM:
-    return err("Gas limit is below minimum")
-  if gasLimit > GAS_LIMIT_MAXIMUM:
-    return err("Gas limit is above maximum")
-
-  let diff = gasLimit - parentGasLimit
-  if diff > (parentGasLimit div GAS_LIMIT_ADJUSTMENT_FACTOR):
-    return err("Gas limit difference to parent is too big")
-
-  result = ok()
-
 proc validateHeader(db: BaseChainDB; header, parentHeader: BlockHeader;
                     numTransactions: int; checkSealOK: bool;
                     hashCache: var EpochHashCache): Result[void,string] =
   if header.extraData.len > 32:
     return err("BlockHeader.extraData larger than 32 bytes")
 
-  result = validateGasLimit(header.gasLimit, parentHeader.gasLimit)
-  if result.isErr:
-    return
-
   if header.gasUsed == 0 and 0 < numTransactions:
     return err("zero gasUsed but tranactions present");
 
@@ -346,9 +317,9 @@ proc validateHeaderAndKinship*(chainDB: BaseChainDB; header: BlockHeader;
       return err("BlockHeader.extraData larger than 32 bytes")
     return ok()
 
-  let parentHeader = chainDB.getBlockHeader(header.parentHash)
+  let parent = chainDB.getBlockHeader(header.parentHash)
   result = chainDB.validateHeader(
-    header, parentHeader,numTransactions,  checkSealOK, hashCache)
+    header, parent, numTransactions, checkSealOK, hashCache)
   if result.isErr:
     return
 
@@ -360,7 +331,7 @@ proc validateHeaderAndKinship*(chainDB: BaseChainDB; header: BlockHeader;
 
   result = chainDB.validateUncles(header, uncles, checkSealOK, hashCache)
   if result.isOk:
-    result = chainDB.validateGaslimit(header)
+    result = chainDB.validateGasLimitOrBaseFee(header, parent)
 
 
 proc validateHeaderAndKinship*(chainDB: BaseChainDB;

nimbus/utils/header.nim

@@ -19,16 +19,6 @@ proc hasUncles*(header: BlockHeader): bool = header.ommersHash != EMPTY_UNCLE_HA
 proc `$`*(header: BlockHeader): string =
   result = &"BlockHeader(timestamp: {header.timestamp} difficulty: {header.difficulty} blockNumber: {header.blockNumber} gasLimit: {header.gasLimit})"
 
-proc gasLimitBounds*(parent: BlockHeader): (GasInt, GasInt) =
-  ## Compute the boundaries for the block gas limit based on the parent block.
-  let
-    boundaryRange = (parent.gasLimit div GAS_LIMIT_ADJUSTMENT_FACTOR)
-    upperBound = if GAS_LIMIT_MAXIMUM - boundaryRange < parent.gasLimit:
-      GAS_LIMIT_MAXIMUM else: parent.gasLimit + boundaryRange
-    lowerBound = max(GAS_LIMIT_MINIMUM, parent.gasLimit - boundaryRange)
-
-  return (lowerBound, upperBound)
-
 proc computeGasLimit*(parent: BlockHeader, gasLimitFloor: GasInt): GasInt =
   #[
     For each block: