Exception is thrown when parsing typedData (bad encoding)

[Toporin]

When I try to encode typedData from various dapps, an exception is sometimes thrown with the following error:

exception while parsing typedData: Value '2' of type <class 'str'> cannot be encoded by UnsignedIntegerEncoder

For example:

`

typed_data= {"types":{"EIP712Domain":[{"name":"name","type":"string"},{"name":"version","type":"string"},{"name":"chainId","type":"uint256"},{"name":"verifyingContract","type":"address"}],"OrderComponents":[{"name":"offerer","type":"address"},{"name":"zone","type":"address"},{"name":"offer","type":"OfferItem[]"},{"name":"consideration","type":"ConsiderationItem[]"},{"name":"orderType","type":"uint8"},{"name":"startTime","type":"uint256"},{"name":"endTime","type":"uint256"},{"name":"zoneHash","type":"bytes32"},{"name":"salt","type":"uint256"},{"name":"conduitKey","type":"bytes32"},{"name":"counter","type":"uint256"}],"OfferItem":[{"name":"itemType","type":"uint8"},{"name":"token","type":"address"},{"name":"identifierOrCriteria","type":"uint256"},{"name":"startAmount","type":"uint256"},{"name":"endAmount","type":"uint256"}],"ConsiderationItem":[{"name":"itemType","type":"uint8"},{"name":"token","type":"address"},{"name":"identifierOrCriteria","type":"uint256"},{"name":"startAmount","type":"uint256"},{"name":"endAmount","type":"uint256"},{"name":"recipient","type":"address"}]},"primaryType":"OrderComponents","domain":{"name":"Seaport","version":"1.1","chainId":"1","verifyingContract":"0x00000000006c3852cbEf3e08E8dF289169EdE581"},"message":{"offerer":"0xF23aDCE99089BD884Dfc860a4178046E26Efc79F","offer":[{"itemType":"2","token":"0x57f1887a8BF19b14fC0dF6Fd9B2acc9Af147eA85","identifierOrCriteria":"79283735726345475554244090083354043673577121378327128667043370997501889156666","startAmount":"1","endAmount":"1"}],"consideration":[{"itemType":"1","token":"0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2","identifierOrCriteria":"0","startAmount":"309075000000000000","endAmount":"309075000000000000","recipient":"0xF23aDCE99089BD884Dfc860a4178046E26Efc79F"},{"itemType":"1","token":"0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2","identifierOrCriteria":"0","startAmount":"7925000000000000","endAmount":"7925000000000000","recipient":"0x0000a26b00c1F0DF003000390027140000fAa719"}],"startTime":"1662714094","endTime":"1662973294","orderType":"2","zone":"0x004C00500000aD104D7DBd00e3ae0A5C00560C00","zoneHash":"0x0000000000000000000000000000000000000000000000000000000000000000","salt":"11315322929827309","conduitKey":"0x0000007b02230091a7ed01230072f7006a004d60a8d4e71d599b8104250f0000","totalOriginalConsiderationItems":"2","counter":"0"}}
from py_eth_sig_utils import eip712
msg_hash= eip712.encoding.encode_typed_data(typed_data)
`

This returns the following error:

Value '2' of type <class 'str'> cannot be encoded by UnsignedIntegerEncoder

As far as I can tell, this is due to wrong encoding of the typedData, e.g. "orderType":"2" (a string) despite the fact that "orderType" is defined as a uint8 and py-eth-sig-utils expects an int, not a string. A similar issue arises with "bytes32" types.

Since it appears a significant number of dapps mismatch encoding for "int", "uint" and "bytes*" as string, is it possible to sanitize format before encoding and correct any wrong encoding instead of throwing exception?**

Here is a quick and dirty patch that seems to do the trick (in encoding.py):

def encode_value(dataType, value, types):
    print(f"DEBUG py_eth_sig_utils: in encode_value: data_type:{dataType}, value:{value}")
    if (dataType == 'string'):
        return encode_single('bytes32', utils.sha3(value))
    elif (dataType == 'bytes'):
        return encode_single('bytes32', utils.sha3(utils.scan_bin(value)))
    elif (types.get(dataType)):
        return encode_single('bytes32', utils.sha3(encode_data(dataType, value, types)))
    elif (dataType.endswith("]")):
        arrayType = dataType[:dataType.index("[")]
        return encode_single('bytes32', utils.sha3(b"".join([ encode_data(arrayType, arrayValue, types) for arrayValue in value ])))
    else:
        #print(f"DEBUG py_eth_sig_utils: in encode_value: data_type:{dataType}, value:{value}")
        if (dataType.startswith("uint") or dataType.startswith("int")) and isinstance(value, str):
            print(f"DEBUG py_eth_sig_utils: in encode_value: convert string to int!")
            value= int(value)
        if (dataType.startswith("bytes")) and isinstance(value, str):
            print(f"DEBUG py_eth_sig_utils: in encode_value: convert string to bytes!")
            if value.startswith("0x"):
                value= value[2:]
            value= bytes.fromhex(value)
        return encode_single(dataType, value)