diff options
| -rw-r--r-- | packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC20Transfer.sol | 128 |
1 files changed, 126 insertions, 2 deletions
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC20Transfer.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC20Transfer.sol index a09db43bd..7cf6e1989 100644 --- a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC20Transfer.sol +++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC20Transfer.sol @@ -19,11 +19,13 @@ pragma solidity ^0.4.24; pragma experimental ABIEncoderV2; +import "./mixins/MAuthorizable.sol"; import "../../utils/LibBytes/LibBytes.sol"; import "../../tokens/ERC20Token/IERC20Token.sol"; -contract MixinERC20Transfer { - +contract MixinERC20Transfer is + MAuthorizable +{ using LibBytes for bytes; /// @dev Internal version of `transferFrom`. @@ -31,6 +33,128 @@ contract MixinERC20Transfer { /// @param from Address to transfer asset from. /// @param to Address to transfer asset to. /// @param amount Amount of asset to transfer. + function transferFrom( + bytes assetData, + address from, + address to, + uint256 amount + ) + external + onlyAuthorized() + { + // `transferFrom`. + // The function is marked `external`, so no abi decodeding 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. + // + // WARNING: The ABIv2 specification allows additional padding between + // the Params and Data section. This will result in a larger + // offset to assetData. + + // Asset data itself is encoded as follows: + // + // | Area | Offset | Length | Contents | + // |----------|--------|---------|-------------------------------------| + // | Header | 0 | 4 | function selector | + // | Params | | 1 * 32 | function parameters: | + // | | 4 | 12 + 20 | 1. token address | + + // Transfer tokens. + // We do a raw call so we can check the success separate + // from the return data. + // We construct calldata for the `token.transferFrom` ABI. + // The layout of this calldata is in the table below. + // + // | Area | Offset | Length | Contents | + // |----------|--------|---------|-------------------------------------| + // | Header | 0 | 4 | function selector | + // | Params | | 3 * 32 | function parameters: | + // | | 4 | | 1. from | + // | | 36 | | 2. to | + // | | 68 | | 3. amount | + + bytes4 transferFromSelector = IERC20Token(0).transferFrom.selector; + bool success; + assembly { + /////// Token contract address /////// + // The token address is found as follows: + // * It is stored at offset 4 in `assetData` contents. + // * This is stored at offset 32 from `assetData`. + // * The offset to `assetData` from Params is stored at offset + // 4 in calldata. + // * The offset of Params in calldata is 4. + // So we read location 4 and add 32 + 4 + 4 to it. + let token := calldataload(add(calldataload(4), 40)) + + /////// Setup State /////// + // `cdStart` is the start of the calldata for `token.transferFrom` (equal to free memory ptr). + let cdStart := mload(64) + + /////// Setup Header Area /////// + // This area holds the 4-byte `transferFromSelector`. + // Any trailing data in transferFromSelector will be + // overwritten in the next `mstore` call. + mstore(cdStart, transferFromSelector) + + /////// Setup Params Area /////// + // We copy the fields `from`, `to` and `amount` in bulk + // from our own calldata to the new calldata. + calldatacopy(add(cdStart, 4), 36, 96) + + /////// Call `token.transferFrom` using the calldata /////// + success := call( + gas, // forward all gas + token, // call address of token contract + 0, // don't send any ETH + cdStart, // pointer to start of input + 100, // length of input + cdStart, // write output over input + 32 // output size should be 32 bytes + ) + + /////// Check return data. /////// + // If there is no return data, we assume the token incorrectly + // does not return a bool. In this case we expect it to revert + // on failure, which was handled above. + // If the token does return data, we require that it is a single + // nonzero 32 bytes value. + // So the transfer succeeded if the call succeeded and either + // returned nothing, or returned a non-zero 32 byte value. + success := and(success, or( + iszero(returndatasize), + and( + eq(returndatasize, 32), + gt(mload(cdStart), 0) + ) + )) + } + require( + success, + "TRANSFER_FAILED" + ); + } + + + /// @dev Internal version of `transferFrom`. + /// @param assetData Encoded byte array. + /// @param from Address to transfer asset from. + /// @param to Address to transfer asset to. + /// @param amount Amount of asset to transfer. function transferFromInternal( bytes memory assetData, address from, |