Split parent_header from validate_header

Author: SamWilsn

src/ethereum/arrow_glacier/fork.py

@@ -174,7 +174,8 @@ def state_transition(chain: BlockChain, block: Block) -> None:
     block :
         Block to apply to `chain`.
     """
-    validate_header(chain, block.header)
+    parent = parent_header(chain, block.header)
+    validate_header(block.header, parent)
     validate_ommers(block.ommers, block.header, chain)
 
     block_env = vm.BlockEnvironment(
@@ -281,7 +282,24 @@ def calculate_base_fee_per_gas(
     return Uint(expected_base_fee_per_gas)
 
 
-def validate_header(chain: BlockChain, header: AnyHeader) -> None:
+def parent_header(chain: BlockChain, header: AnyHeader) -> AnyHeader:
+    """
+    Gets the parent of a block, given that block's `header` and `chain`.
+    """
+    if header.number < Uint(1):
+        raise InvalidBlock
+
+    parent_number = header.number - Uint(1)
+    first_number = chain.blocks[0].header.number
+    last_number = chain.blocks[-1].header.number
+
+    if parent_number < first_number or parent_number > last_number:
+        raise InvalidBlock
+
+    return chain.blocks[parent_number - first_number].header
+
+
+def validate_header(header: AnyHeader, parent_header: AnyHeader) -> None:
     """
     Verifies a block header.
 
@@ -294,30 +312,14 @@ def validate_header(chain: BlockChain, header: AnyHeader) -> None:
 
     Parameters
     ----------
-    chain :
-        History and current state.
     header :
         Header to check for correctness.
+    parent_header :
+        Parent Header of the header to check for correctness
     """
-    if header.number < Uint(1):
-        raise InvalidBlock
-    parent_header_number = header.number - Uint(1)
-    first_block_number = chain.blocks[0].header.number
-    last_block_number = chain.blocks[-1].header.number
-
-    if (
-        parent_header_number < first_block_number
-        or parent_header_number > last_block_number
-    ):
-        raise InvalidBlock
-
-    parent_header = chain.blocks[
-        parent_header_number - first_block_number
-    ].header
-
     if not isinstance(header, Header):
         assert not isinstance(parent_header, Header)
-        return previous_fork.validate_header(chain, header)
+        return previous_fork.validate_header(header, parent_header)
 
     if header.gas_used > header.gas_limit:
         raise InvalidBlock
@@ -610,7 +612,8 @@ def validate_ommers(
     for ommer in ommers:
         if Uint(1) > ommer.number or ommer.number >= block_header.number:
             raise InvalidBlock
-        validate_header(chain, ommer)
+        parent = parent_header(chain, ommer)
+        validate_header(ommer, parent)
     if len(ommers) > 2:
         raise InvalidBlock
 

src/ethereum/berlin/fork.py

@@ -168,7 +168,8 @@ def state_transition(chain: BlockChain, block: Block) -> None:
     block :
         Block to apply to `chain`.
     """
-    validate_header(chain, block.header)
+    parent = parent_header(chain, block.header)
+    validate_header(block.header, parent)
     validate_ommers(block.ommers, block.header, chain)
 
     block_env = vm.BlockEnvironment(
@@ -212,7 +213,24 @@ def state_transition(chain: BlockChain, block: Block) -> None:
         chain.blocks = chain.blocks[-255:]
 
 
-def validate_header(chain: BlockChain, header: AnyHeader) -> None:
+def parent_header(chain: BlockChain, header: AnyHeader) -> AnyHeader:
+    """
+    Gets the parent of a block, given that block's `header` and `chain`.
+    """
+    if header.number < Uint(1):
+        raise InvalidBlock
+
+    parent_number = header.number - Uint(1)
+    first_number = chain.blocks[0].header.number
+    last_number = chain.blocks[-1].header.number
+
+    if parent_number < first_number or parent_number > last_number:
+        raise InvalidBlock
+
+    return chain.blocks[parent_number - first_number].header
+
+
+def validate_header(header: AnyHeader, parent_header: AnyHeader) -> None:
     """
     Verifies a block header.
 
@@ -225,33 +243,17 @@ def validate_header(chain: BlockChain, header: AnyHeader) -> None:
 
     Parameters
     ----------
-    chain :
-        History and current state.
     header :
         Header to check for correctness.
+    parent_header :
+        Parent Header of the header to check for correctness
     """
-    if header.number < Uint(1):
-        raise InvalidBlock
-    parent_header_number = header.number - Uint(1)
-    first_block_number = chain.blocks[0].header.number
-    last_block_number = chain.blocks[-1].header.number
-
-    if (
-        parent_header_number < first_block_number
-        or parent_header_number > last_block_number
-    ):
-        raise InvalidBlock
-
-    parent_header = chain.blocks[
-        parent_header_number - first_block_number
-    ].header
-
     if header.gas_used > header.gas_limit:
         raise InvalidBlock
 
     if not isinstance(header, Header):
         assert not isinstance(parent_header, Header)
-        return previous_fork.validate_header(chain, header)
+        return previous_fork.validate_header(header, parent_header)
 
     parent_has_ommers = parent_header.ommers_hash != EMPTY_OMMER_HASH
     if header.timestamp <= parent_header.timestamp:
@@ -509,7 +511,8 @@ def validate_ommers(
     for ommer in ommers:
         if Uint(1) > ommer.number or ommer.number >= block_header.number:
             raise InvalidBlock
-        validate_header(chain, ommer)
+        parent = parent_header(chain, ommer)
+        validate_header(ommer, parent)
     if len(ommers) > 2:
         raise InvalidBlock
 

src/ethereum/byzantium/fork.py

@@ -155,7 +155,8 @@ def state_transition(chain: BlockChain, block: Block) -> None:
     block :
         Block to apply to `chain`.
     """
-    validate_header(chain, block.header)
+    parent = parent_header(chain, block.header)
+    validate_header(block.header, parent)
     validate_ommers(block.ommers, block.header, chain)
 
     block_env = vm.BlockEnvironment(
@@ -199,7 +200,24 @@ def state_transition(chain: BlockChain, block: Block) -> None:
         chain.blocks = chain.blocks[-255:]
 
 
-def validate_header(chain: BlockChain, header: AnyHeader) -> None:
+def parent_header(chain: BlockChain, header: AnyHeader) -> AnyHeader:
+    """
+    Gets the parent of a block, given that block's `header` and `chain`.
+    """
+    if header.number < Uint(1):
+        raise InvalidBlock
+
+    parent_number = header.number - Uint(1)
+    first_number = chain.blocks[0].header.number
+    last_number = chain.blocks[-1].header.number
+
+    if parent_number < first_number or parent_number > last_number:
+        raise InvalidBlock
+
+    return chain.blocks[parent_number - first_number].header
+
+
+def validate_header(header: AnyHeader, parent_header: AnyHeader) -> None:
     """
     Verifies a block header.
 
@@ -212,33 +230,17 @@ def validate_header(chain: BlockChain, header: AnyHeader) -> None:
 
     Parameters
     ----------
-    chain :
-        History and current state.
     header :
         Header to check for correctness.
+    parent_header :
+        Parent Header of the header to check for correctness
     """
-    if header.number < Uint(1):
-        raise InvalidBlock
-    parent_header_number = header.number - Uint(1)
-    first_block_number = chain.blocks[0].header.number
-    last_block_number = chain.blocks[-1].header.number
-
-    if (
-        parent_header_number < first_block_number
-        or parent_header_number > last_block_number
-    ):
-        raise InvalidBlock
-
-    parent_header = chain.blocks[
-        parent_header_number - first_block_number
-    ].header
-
     if header.gas_used > header.gas_limit:
         raise InvalidBlock
 
     if not isinstance(header, Header):
         assert not isinstance(parent_header, Header)
-        return previous_fork.validate_header(chain, header)
+        return previous_fork.validate_header(header, parent_header)
 
     parent_has_ommers = parent_header.ommers_hash != EMPTY_OMMER_HASH
     if header.timestamp <= parent_header.timestamp:
@@ -493,7 +495,8 @@ def validate_ommers(
     for ommer in ommers:
         if Uint(1) > ommer.number or ommer.number >= block_header.number:
             raise InvalidBlock
-        validate_header(chain, ommer)
+        parent = parent_header(chain, ommer)
+        validate_header(ommer, parent)
     if len(ommers) > 2:
         raise InvalidBlock
 

src/ethereum/cancun/fork.py

@@ -187,7 +187,8 @@ def state_transition(chain: BlockChain, block: Block) -> None:
     block :
         Block to apply to `chain`.
     """
-    validate_header(chain, block.header)
+    parent = parent_header(chain, block.header)
+    validate_header(parent, block.header)
     if block.ommers != ():
         raise InvalidBlock
 
@@ -302,7 +303,24 @@ def calculate_base_fee_per_gas(
     return Uint(expected_base_fee_per_gas)
 
 
-def validate_header(chain: BlockChain, header: AnyHeader) -> None:
+def parent_header(chain: BlockChain, header: AnyHeader) -> AnyHeader:
+    """
+    Gets the parent of a block, given that block's `header` and `chain`.
+    """
+    if header.number < Uint(1):
+        raise InvalidBlock
+
+    parent_number = header.number - Uint(1)
+    first_number = chain.blocks[0].header.number
+    last_number = chain.blocks[-1].header.number
+
+    if parent_number < first_number or parent_number > last_number:
+        raise InvalidBlock
+
+    return chain.blocks[parent_number - first_number].header
+
+
+def validate_header(header: AnyHeader, parent_header: AnyHeader) -> None:
     """
     Verifies a block header.
 
@@ -315,35 +333,19 @@ def validate_header(chain: BlockChain, header: AnyHeader) -> None:
 
     Parameters
     ----------
-    chain :
-        History and current state.
     header :
         Header to check for correctness.
+    parent_header :
+        Parent Header of the header to check for correctness
     """
-    if header.number < Uint(1):
-        raise InvalidBlock
-    parent_header_number = header.number - Uint(1)
-    first_block_number = chain.blocks[0].header.number
-    last_block_number = chain.blocks[-1].header.number
-
-    if (
-        parent_header_number < first_block_number
-        or parent_header_number > last_block_number
-    ):
-        raise InvalidBlock
-
-    parent_header = chain.blocks[
-        parent_header_number - first_block_number
-    ].header
+    if not isinstance(header, Header):
+        assert not isinstance(parent_header, Header)
+        return previous_fork.validate_header(header, parent_header)
 
     excess_blob_gas = calculate_excess_blob_gas(parent_header)
     if header.excess_blob_gas != excess_blob_gas:
         raise InvalidBlock
 
-    if not isinstance(header, Header):
-        assert not isinstance(parent_header, Header)
-        return previous_fork.validate_header(chain, header)
-
     if header.gas_used > header.gas_limit:
         raise InvalidBlock