ethereum: Fix adapter to filter proxy calls #3219
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Without this the line that does `function_abi.decode_input(&call.input.0[4..])` was failing with the Err(InvalidData). For some reason some of the OpenSea Proxy contracts don't get recognized as DELEGATECALL, instead they are seen as CALLs, but you can identify them by the input having the wrong size since it's a fallback function call. A scenario to exemplify the problem, can be seen in this transaction: 0x4499dc75facb4cd27894196aac00bcb0ffbe3d64de87105878451d5637662f90 We would get the traces for the block 14043345 (0xD648D1) for the contract 0x7Be8076f4EA4A4AD08075C2508e481d6C946D12b. Then we would find two CALLs for the `atomicMatch_` function. However the first one would have the wrong size (fail at decoding) and the second one would be correct. That's because of the proxy and because of how fallbacks are compiled from Solidity (omitting the function signature, aka a feel bytes less).
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chain/ethereum/src/adapter.rs
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| if let None = v { | ||
| return false; | ||
| } | ||
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| let signature = &v.unwrap().1; |
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Suggested change
| if let None = v { | |
| return false; | |
| } | |
| let signature = &v.unwrap().1; | |
| let signature = match v { | |
| None => return false, | |
| Some(v) => &v.1, | |
| } |
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I've wrapped this suggestion with the self.contract_addresses_function_signatures.get(&call.to) function call, so there's no more v let definition.
chain/ethereum/src/adapter.rs
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| let correct_fn = signature.contains(&call.input.0[..4]); | ||
| // Not multiple of 32, wrong length to decode parameters. | ||
| // This is probably a delegatecall disguised as a regular call | ||
| // via fallback. |
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Is there a reference you can link here if somebody wants to better understand how this happens? Maybe link an example trace in etherscan?
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I've improved the comment, can you check if it's good now please?
chain/ethereum/src/adapter.rs
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| let wrong_input_size = (call.input.0.len() - 4) % 32 != 0; | ||
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| correct_fn && !wrong_input_size |
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| let wrong_input_size = (call.input.0.len() - 4) % 32 != 0; | |
| correct_fn && !wrong_input_size | |
| let correct_input_size = (call.input.0.len() - 4) % 32 == 0; | |
| correct_fn && correct_input_size |
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* ethereum: Fix adapter to filter proxy calls Without this the line that does `function_abi.decode_input(&call.input.0[4..])` was failing with the Err(InvalidData). For some reason some of the OpenSea Proxy contracts don't get recognized as DELEGATECALL, instead they are seen as CALLs, but you can identify them by the input having the wrong size since it's a fallback function call. A scenario to exemplify the problem, can be seen in this transaction: 0x4499dc75facb4cd27894196aac00bcb0ffbe3d64de87105878451d5637662f90 We would get the traces for the block 14043345 (0xD648D1) for the contract 0x7Be8076f4EA4A4AD08075C2508e481d6C946D12b. Then we would find two CALLs for the `atomicMatch_` function. However the first one would have the wrong size (fail at decoding) and the second one would be correct. That's because of the proxy and because of how fallbacks are compiled from Solidity (omitting the function signature, aka a feel bytes less). * ethereum: Apply code review suggestions for the adapter * ethereum: Elaborate/improve comment about call input size
evaporei
added a commit
that referenced
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Feb 8, 2022
* ethereum: Fix adapter to filter proxy calls Without this the line that does `function_abi.decode_input(&call.input.0[4..])` was failing with the Err(InvalidData). For some reason some of the OpenSea Proxy contracts don't get recognized as DELEGATECALL, instead they are seen as CALLs, but you can identify them by the input having the wrong size since it's a fallback function call. A scenario to exemplify the problem, can be seen in this transaction: 0x4499dc75facb4cd27894196aac00bcb0ffbe3d64de87105878451d5637662f90 We would get the traces for the block 14043345 (0xD648D1) for the contract 0x7Be8076f4EA4A4AD08075C2508e481d6C946D12b. Then we would find two CALLs for the `atomicMatch_` function. However the first one would have the wrong size (fail at decoding) and the second one would be correct. That's because of the proxy and because of how fallbacks are compiled from Solidity (omitting the function signature, aka a feel bytes less). * ethereum: Apply code review suggestions for the adapter * ethereum: Elaborate/improve comment about call input size
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Without this the line that does
function_abi.decode_input(&call.input.0[4..])was failing with theErr(InvalidData).For some reason some of the OpenSea Proxy contracts don't get recognized as DELEGATECALL, instead they are seen as CALLs, but you can identify them by the input having the wrong size since it's a fallback function call.
A scenario to exemplify the problem, can be seen in this transaction: 0x4499dc75facb4cd27894196aac00bcb0ffbe3d64de87105878451d5637662f90.
We would get the traces for the block
14043345(0xD648D1) for the contract0x7Be8076f4EA4A4AD08075C2508e481d6C946D12b. Then we would find two CALLs for theatomicMatch_function. However the first one would have the wrong size (fail at decoding) and the second one would be correct.That's because of the proxy and because of how fallbacks are compiled from Solidity (omitting the function signature, aka a feel bytes less).
Ethereum ABI (d)ecoding docs: https://docs.soliditylang.org/en/v0.8.11/abi-spec.html.
Fixes #3194