added a check for POA extraData

WIP

fixed apply_formatter_index_at

tests/core/eth-module/test_poa.py

@@ -1,5 +1,8 @@
 import pytest
 
+from web3.exceptions import (
+    ValidationError,
+)
 from web3.middleware import (
     construct_fixture_middleware,
     geth_poa_middleware,
@@ -12,7 +15,7 @@ def test_long_extra_data(web3):
         'eth_getBlockByNumber': {'extraData': '0x' + 'ff' * 33},
     })
     web3.middleware_stack.inject(return_block_with_long_extra_data, layer=0)
-    with pytest.raises(ValueError):
+    with pytest.raises(ValidationError):
         web3.eth.getBlock('latest')
 
 

web3/middleware/formatting.py

@@ -5,20 +5,27 @@
 
 def construct_formatting_middleware(request_formatters=None,
                                     result_formatters=None,
-                                    error_formatters=None):
+                                    error_formatters=None,
+                                    request_formatters_with_web3=None):
     if request_formatters is None:
         request_formatters = {}
     if result_formatters is None:
         result_formatters = {}
     if error_formatters is None:
         error_formatters = {}
+    if request_formatters_with_web3 is None:
+        request_formatters_with_web3 = {}
 
     def formatter_middleware(make_request, web3):
         def middleware(method, params):
             if method in request_formatters:
                 formatter = request_formatters[method]
                 formatted_params = formatter(params)
                 response = make_request(method, formatted_params)
+            elif method in request_formatters_with_web3:
+                formatter = request_formatters_with_web3[method]
+                formatted_params = formatter(web3, params)
+                response = make_request(method, formatted_params)
             else:
                 response = make_request(method, params)
 

web3/middleware/validation.py

@@ -5,15 +5,26 @@
 )
 from eth_utils.curried import (
     apply_formatter_at_index,
+    apply_formatter_if,
     apply_formatters_to_dict,
 )
+from hexbytes import (
+    HexBytes,
+)
 
 from web3.exceptions import (
     ValidationError,
 )
+from web3.middleware.formatting import (
+    construct_formatting_middleware,
+)
+from web3.utils.formatters import (
+    apply_formatter_with_web3_at_index,
+    apply_formatters_with_web3_to_dict,
+    is_not_null,
+)
 
 
-@curry
 def validate_chain_id(web3, chain_id):
     if chain_id == web3.version.network:
         return None
@@ -27,21 +38,62 @@ def validate_chain_id(web3, chain_id):
         )
 
 
+@curry
+def check_extradata_length(val, length):
+    if not isinstance(val, (str, int, bytes)):
+        return val
+    result = HexBytes(val)
+    if len(result) > length:
+        raise ValidationError(
+            "The field extraData is %d bytes, but should be %d. "
+            "It is quite likely that you are connected to a POA chain. "
+            "Refer "
+            "http://web3py.readthedocs.io/en/latest/middleware.html#geth-style-proof-of-authority "
+            "for more details. The full extraData is: %r" % (
+                len(result), length, result
+            )
+        )
+    return val
+
+
 def transaction_normalizer(transaction):
     return dissoc(transaction, 'chainId')
 
 
-def validation_middleware(make_request, web3):
-    transaction_validator = apply_formatters_to_dict({
-        'chainId': validate_chain_id(web3),
-    })
+BLOCK_VALIDATORS = {
+    'extraData': check_extradata_length(length=32),
+}
+
 
-    transaction_sanitizer = compose(transaction_normalizer, transaction_validator)
+block_validator = apply_formatters_to_dict(BLOCK_VALIDATORS)
 
-    def middleware(method, params):
-        if method in {'eth_sendTransaction', 'eth_estimateGas', 'eth_call'}:
-            post_validated_params = apply_formatter_at_index(transaction_sanitizer, 0, params)
-            return make_request(method, post_validated_params)
-        else:
-            return make_request(method, params)
-    return middleware
+
+TRANSACTION_PARAMS_VALIDATORS = apply_formatters_with_web3_to_dict({
+    'chainId': validate_chain_id,
+})
+
+
+transaction_params_validator = apply_formatter_with_web3_at_index(
+    TRANSACTION_PARAMS_VALIDATORS,
+    0,
+)
+
+chain_id_validator = compose(
+    apply_formatter_at_index(transaction_normalizer, 0),
+    transaction_params_validator
+)
+
+extra_data_validator = apply_formatter_if(is_not_null, block_validator)
+
+
+validation_middleware = construct_formatting_middleware(
+    request_formatters_with_web3={
+        'eth_sendTransaction': chain_id_validator,
+        'eth_estimateGas': chain_id_validator,
+        'eth_call': chain_id_validator,
+    },
+    result_formatters={
+        'eth_getBlockByHash': extra_data_validator,
+        'eth_getBlockByNumber': extra_data_validator,
+    },
+)

web3/utils/formatters.py

@@ -4,6 +4,7 @@
 )
 
 from cytoolz import (
+    complement,
     dissoc,
 )
 from cytoolz.functoolz import (
@@ -13,6 +14,7 @@
 from eth_utils import (
     is_dict,
     is_list_like,
+    is_null,
     is_string,
     to_dict,
     to_list,
@@ -30,6 +32,9 @@ def hex_to_integer(value):
 integer_to_hex = hex
 
 
+is_not_null = complement(is_null)
+
+
 @curry
 @to_list
 def apply_formatter_at_index(formatter, at_index, value):
@@ -158,3 +163,18 @@ def remove_key_if(key, remove_if, input_dict):
         return dissoc(input_dict, key)
     else:
         return input_dict
+
+
+@curry
+def apply_formatter_with_web3_at_index(validator, at_index, web3, value):
+    _validator = curry(validator)(web3)
+    return apply_formatter_at_index(_validator, at_index, value)
+
+
+@curry
+def apply_formatters_with_web3_to_dict(validators, web3, value):
+    class _dict(dict):
+        def __getitem__(self, key):
+            validator = super().__getitem__(key)
+            return curry(validator)(web3)
+    return apply_formatters_to_dict(_dict(validators), value)