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Implement StaticCallProxy #1863
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| Original file line number | Diff line number | Diff line change | ||||
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| /* | ||||||
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| Copyright 2018 ZeroEx Intl. | ||||||
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| Licensed under the Apache License, Version 2.0 (the "License"); | ||||||
| you may not use this file except in compliance with the License. | ||||||
| You may obtain a copy of the License at | ||||||
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| http://www.apache.org/licenses/LICENSE-2.0 | ||||||
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| Unless required by applicable law or agreed to in writing, software | ||||||
| distributed under the License is distributed on an "AS IS" BASIS, | ||||||
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||||||
| See the License for the specific language governing permissions and | ||||||
| limitations under the License. | ||||||
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| */ | ||||||
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| pragma solidity ^0.5.9; | ||||||
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| contract StaticCallProxy { | ||||||
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| // Id of this proxy. | ||||||
| bytes4 constant internal PROXY_ID = bytes4(keccak256("StaticCall(address,bytes,bytes32)")); | ||||||
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| // solhint-disable-next-line payable-fallback | ||||||
| function () | ||||||
| external | ||||||
| { | ||||||
| assembly { | ||||||
| // The first 4 bytes of calldata holds the function selector | ||||||
| let selector := and(calldataload(0), 0xffffffff00000000000000000000000000000000000000000000000000000000) | ||||||
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| // `transferFrom` will be called with the following parameters: | ||||||
| // assetData Encoded byte array. | ||||||
| // from Address to transfer asset from. | ||||||
| // to Address to transfer asset to. | ||||||
| // amount Amount of asset to transfer. | ||||||
| // bytes4(keccak256("transferFrom(bytes,address,address,uint256)")) = 0xa85e59e4 | ||||||
| if eq(selector, 0xa85e59e400000000000000000000000000000000000000000000000000000000) { | ||||||
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| // `transferFrom`. | ||||||
| // The function is marked `external`, so no abi decoding is done for | ||||||
| // us. Instead, we expect the `calldata` memory to contain the | ||||||
| // following: | ||||||
| // | ||||||
| // | Area | Offset | Length | Contents | | ||||||
| // |----------|--------|---------|-------------------------------------| | ||||||
| // | Header | 0 | 4 | function selector | | ||||||
| // | Params | | 4 * 32 | function parameters: | | ||||||
| // | | 4 | | 1. offset to assetData (*) | | ||||||
| // | | 36 | | 2. from | | ||||||
| // | | 68 | | 3. to | | ||||||
| // | | 100 | | 4. amount | | ||||||
| // | Data | | | assetData: | | ||||||
| // | | 132 | 32 | assetData Length | | ||||||
| // | | 164 | ** | assetData Contents | | ||||||
| // | ||||||
| // (*): offset is computed from start of function parameters, so offset | ||||||
| // by an additional 4 bytes in the calldata. | ||||||
| // | ||||||
| // (**): see table below to compute length of assetData Contents | ||||||
| // (***): Note that the `from`, `to`, and `amount` params in calldata are ignored in this function. | ||||||
| // | ||||||
| // WARNING: The ABIv2 specification allows additional padding between | ||||||
| // the Params and Data section. This will result in a larger | ||||||
| // offset to assetData. | ||||||
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| // Load offset to `assetData` | ||||||
| let assetDataOffset := add(calldataload(4), 4) | ||||||
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| // Validate length of `assetData` | ||||||
| let assetDataLen := calldataload(assetDataOffset) | ||||||
| if or(lt(assetDataLen, 100), mod(sub(assetDataLen, 4), 32)) { | ||||||
|
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There was a problem hiding this comment. Interesting. I guess this also explains why we word align revert strings. |
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| // Revert with `Error("INVALID_ASSET_DATA_LENGTH")` | ||||||
| mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000) | ||||||
| mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000) | ||||||
| mstore(64, 0x00000019494e56414c49445f41535345545f444154415f4c454e475448000000) | ||||||
| mstore(96, 0) | ||||||
| revert(0, 100) | ||||||
| } | ||||||
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| // Ensure that `assetData` ends inside of calldata | ||||||
| let assetDataEnd := add(assetDataOffset, add(assetDataLen, 32)) | ||||||
| if gt(assetDataEnd, calldatasize()) { | ||||||
| // Revert with `Error("INVALID_ASSET_DATA_END")` | ||||||
| mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000) | ||||||
| mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000) | ||||||
| mstore(64, 0x00000016494e56414c49445f41535345545f444154415f454e44000000000000) | ||||||
| mstore(96, 0) | ||||||
| revert(0, 100) | ||||||
| } | ||||||
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| // Asset data is encoded as follows: | ||||||
| // | Area | Offset | Length | Contents | | ||||||
| // |----------|-------------|---------|--------------------------------------| | ||||||
| // | Header | 0 | 4 | assetProxyId | | ||||||
| // | Params | | 4 * 32 | function parameters: | | ||||||
| // | | 4 | | 1. address of callTarget | | ||||||
| // | | 36 | | 2. offset to staticCallData (*) | | ||||||
| // | | 68 | | 3. expected 32 byte hash of output | | ||||||
| // | Data | | | staticCallData: | | ||||||
| // | | 100 | 32 | 1. staticCallData Length | | ||||||
| // | | 132 | a | 2. staticCallData Contents | | ||||||
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| // In order to find the offset to `staticCallData`, we must add: | ||||||
| // assetDataOffset | ||||||
| // + 32 (assetData len) | ||||||
| // + 4 (proxyId) | ||||||
| // + 32 (callTarget) | ||||||
| let paramsInAssetDataOffset := add(assetDataOffset, 36) | ||||||
| let staticCallDataOffset := add(paramsInAssetDataOffset, calldataload(add(assetDataOffset, 68))) | ||||||
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| // Load length of `staticCallData` | ||||||
| let staticCallDataLen := calldataload(staticCallDataOffset) | ||||||
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| // Ensure `staticCallData` does not begin to outside of `assetData` | ||||||
| let staticCallDataBegin := add(staticCallDataOffset, 32) | ||||||
| let staticCallDataEnd := add(staticCallDataBegin, staticCallDataLen) | ||||||
| if gt(staticCallDataEnd, assetDataEnd) { | ||||||
| // Revert with `Error("INVALID_STATIC_CALL_DATA_OFFSET")` | ||||||
| mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000) | ||||||
| mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000) | ||||||
| mstore(64, 0x0000001f494e56414c49445f5354415449435f43414c4c5f444154415f4f4646) | ||||||
| mstore(96, 0x5345540000000000000000000000000000000000000000000000000000000000) | ||||||
| revert(0, 100) | ||||||
| } | ||||||
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| // Copy `staticCallData` into memory | ||||||
| calldatacopy( | ||||||
| 0, // memory can be safely overwritten from beginning | ||||||
| staticCallDataBegin, // start of `staticCallData` | ||||||
| staticCallDataLen // copy the entire `staticCallData` | ||||||
| ) | ||||||
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| // In order to find the offset to `callTarget`, we must add: | ||||||
| // assetDataOffset | ||||||
| // + 32 (assetData len) | ||||||
| // + 4 (proxyId) | ||||||
| let callTarget := and( | ||||||
| calldataload(add(assetDataOffset, 36)), | ||||||
| 0x000000000000000000000000ffffffffffffffffffffffffffffffffffffffff | ||||||
| ) | ||||||
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| // Perform `callTarget.staticcall(staticCallData)` | ||||||
| let success := staticcall( | ||||||
| gas, // forward all gas | ||||||
| callTarget, // call address `callTarget` | ||||||
| 0, // pointer to start of input | ||||||
| staticCallDataLen, // length of input | ||||||
| 0, // start of memory can be safely overwritten | ||||||
| 0 // don't copy output to memory | ||||||
| ) | ||||||
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| // Copy entire output to start of memory | ||||||
| let outputLen := returndatasize() | ||||||
| returndatacopy( | ||||||
| 0, // copy to memory at 0 | ||||||
| 0, // copy from return data at 0 | ||||||
| outputLen // copy all return data | ||||||
| ) | ||||||
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| // Revert with reason given by `callTarget` if staticcall is unsuccessful | ||||||
| if iszero(success) { | ||||||
| revert(0, outputLen) | ||||||
| } | ||||||
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| // Calculate hash of output | ||||||
| let callResultHash := keccak256(0, outputLen) | ||||||
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| // In order to find the offset to `expectedCallResultHash`, we must add: | ||||||
| // assetDataOffset | ||||||
| // + 32 (assetData len) | ||||||
| // + 4 (proxyId) | ||||||
| // + 32 (callTarget) | ||||||
| // + 32 (staticCallDataOffset) | ||||||
| let expectedResultHash := calldataload(add(assetDataOffset, 100)) | ||||||
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| if sub(callResultHash, expectedResultHash) { | ||||||
| // Revert with `Error("UNEXPECTED_STATIC_CALL_RESULT")` | ||||||
| mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000) | ||||||
| mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000) | ||||||
| mstore(64, 0x0000001d554e45585045435445445f5354415449435f43414c4c5f524553554c) | ||||||
| mstore(96, 0x5400000000000000000000000000000000000000000000000000000000000000) | ||||||
| revert(0, 100) | ||||||
| } | ||||||
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| // Return if output matched expected output | ||||||
| return(0, 0) | ||||||
| } | ||||||
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| // Revert if undefined function is called | ||||||
| revert(0, 0) | ||||||
| } | ||||||
| } | ||||||
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| /// @dev Gets the proxy id associated with the proxy address. | ||||||
| /// @return Proxy id. | ||||||
| function getProxyId() | ||||||
| external | ||||||
| pure | ||||||
| returns (bytes4) | ||||||
| { | ||||||
| return PROXY_ID; | ||||||
| } | ||||||
| } | ||||||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,82 @@ | ||
| /* | ||
|
|
||
| Copyright 2018 ZeroEx Intl. | ||
|
|
||
| Licensed under the Apache License, Version 2.0 (the "License"); | ||
| you may not use this file except in compliance with the License. | ||
| You may obtain a copy of the License at | ||
|
|
||
| http://www.apache.org/licenses/LICENSE-2.0 | ||
|
|
||
| Unless required by applicable law or agreed to in writing, software | ||
| distributed under the License is distributed on an "AS IS" BASIS, | ||
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| See the License for the specific language governing permissions and | ||
| limitations under the License. | ||
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|
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| */ | ||
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| pragma solidity ^0.5.9; | ||
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| import "@0x/contracts-utils/contracts/src/LibBytes.sol"; | ||
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| contract TestStaticCallTarget { | ||
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| using LibBytes for bytes; | ||
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| uint256 internal _state; | ||
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| function updateState() | ||
| external | ||
| { | ||
| _state++; | ||
| } | ||
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| function assertEvenNumber(uint256 target) | ||
| external | ||
| pure | ||
| { | ||
| require( | ||
| target % 2 == 0, | ||
| "TARGET_NOT_EVEN" | ||
| ); | ||
| } | ||
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| function isOddNumber(uint256 target) | ||
| external | ||
| pure | ||
| returns (bool isOdd) | ||
| { | ||
| isOdd = target % 2 == 1; | ||
| return isOdd; | ||
| } | ||
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| function noInputFunction() | ||
|
There was a problem hiding this comment. It could be good to do a sanity check to ensure that |
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| external | ||
| pure | ||
| { | ||
| assert(msg.data.length == 4 && msg.data.readBytes4(0) == bytes4(keccak256("noInputFunction()"))); | ||
| } | ||
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| function dynamicInputFunction(bytes calldata a) | ||
|
There was a problem hiding this comment. It could be good to do some sanity check on the input data, to ensure it was forwarded correctly. |
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| external | ||
| pure | ||
| { | ||
| bytes memory abiEncodedData = abi.encodeWithSignature("dynamicInputFunction(bytes)", a); | ||
| assert(msg.data.equals(abiEncodedData)); | ||
| } | ||
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| function returnComplexType(uint256 a, uint256 b) | ||
| external | ||
| view | ||
| returns (bytes memory result) | ||
| { | ||
| result = abi.encodePacked( | ||
| address(this), | ||
| a, | ||
| b | ||
| ); | ||
| return result; | ||
| } | ||
| } | ||
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Since we're moving towards localizing validation within the proxies, we may want to assert that
amountis some fixed, standardized value -- like0. Ex, in theMultiAssetProxyscaling this value should have no effect.There was a problem hiding this comment.
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The problem is that the
Exchangecontract doesn't allow0transfers. Any non-zero number would be scaled with the MAP.