Allow get_event_data to handle invalid padding bytes

[cwelton]

• Version: 4.7.2
• Python: 3.9.11
• OS: osx/linux
• pip freeze output

attrdict==2.0.1
certifi==2022.5.18.1
charset-normalizer==2.0.12
cytoolz==0.11.2
eth-abi==1.3.0
eth-account==0.3.0
eth-hash==0.3.2
eth-keyfile==0.5.1
eth-keys==0.2.4
eth-rlp==0.2.1
eth-typing==2.3.0
eth-utils==1.10.0
hexbytes==0.2.2
idna==3.3
lru-dict==1.1.7
parsimonious==0.8.1
pycryptodome==3.14.1
requests==2.27.1
rlp==2.0.1
six==1.16.0
toolz==0.11.2
urllib3==1.26.9
web3==4.7.2
websockets==6.0

What was wrong?

Trying to decode an event with bad padding causes a NonEmptyPaddingBytes exception

Note the above linked event is a Transfer event with a to_address of 0x0000000000000000000000010000000000000000000000000000000000000006, which has invalid data in the padding bytes, but is a real event in the blockchain.

• The code which produced the error

from web3.utils.events import get_event_data
from hexbytes import HexBytes


TRANSFER_ABI = {"name":"Transfer","type":"event","anonymous":False,"inputs":[{"indexed":True,"name":"from","type":"address"},{"indexed":True,"name":"to","type":"address"},{"indexed":False,"name":"raw_value","type":"uint256"}]}

myevent = {
  'log_index': 0,
  'transaction_hash': HexBytes('0x93f2a3e74d2d6d636c14d5f63348dbd03e256f4e35f222814554881ce7b2d26a'),
  'transaction_index': 7,
  'block_hash': HexBytes('0xe87449740310af0b5b819b4978694a72bf1a959ac88e387749b8f73c0d7481fb'),
  'block_number': 4086410,
  'address': '0x48c80f1f4d53d5951e5d5438b54cba84f29f32a5',
  'data': HexBytes('0x0000000000000000000000000000000000000000000000000de0b6b3a7640000'),
  'topics': [
    HexBytes('0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef'),
    HexBytes('0x0000000000000000000000007e614ec62cfd5761f20a9c5a2fe2bc0ac7431918'),
    HexBytes('0x0000000000000000000000010000000000000000000000000000000000000006')
  ]
}
get_event_data(TRANSFER_ABI, myevent)

• The full output of the error

Traceback (most recent call last):
  File "/Users/cwelton/projects/definitive/foo/repo.py", line 24, in <module>
    get_event_data(TRANSFER_ABI, myevent)
  File "/Users/cwelton/.pyenv/versions/3.9.11/lib/python3.9/site-packages/web3/utils/events.py", line 195, in get_event_data
    decoded_topic_data = [
  File "/Users/cwelton/.pyenv/versions/3.9.11/lib/python3.9/site-packages/web3/utils/events.py", line 196, in <listcomp>
    decode_single(topic_type, topic_data)
  File "/Users/cwelton/.pyenv/versions/3.9.11/lib/python3.9/site-packages/eth_abi/abi.py", line 80, in decode_single
    return decoder(stream)
  File "/Users/cwelton/.pyenv/versions/3.9.11/lib/python3.9/site-packages/eth_abi/decoding.py", line 118, in __call__
    return self.decode(stream)
  File "/Users/cwelton/.pyenv/versions/3.9.11/lib/python3.9/site-packages/eth_abi/decoding.py", line 189, in decode
    self.validate_padding_bytes(value, padding_bytes)
  File "/Users/cwelton/.pyenv/versions/3.9.11/lib/python3.9/site-packages/eth_abi/decoding.py", line 320, in validate_padding_bytes
    raise NonEmptyPaddingBytes(
eth_abi.exceptions.NonEmptyPaddingBytes: Padding bytes were not empty: b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01'

• What type of node you were connecting to?

Not needed to reproduce

How can it be fixed?

Provide an optional flag to get_event_data (or alternatively always) that would allow parse with warning rather than failing to parse.

[kclowes]

We could put this in our queue, but I'm not sure when we'll be able to get to it. I assume you've seen the processReceipt docs? You can pass a flag to processReceipt. Also a word of caution: get_event_data isn't part of the public API, so it may change in minor version releases.