diff options
Diffstat (limited to 'packages/contracts/src')
| -rw-r--r-- | packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC721Transfer.sol | 168 | ||||
| -rw-r--r-- | packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibTransferErrors.sol | 1 |
2 files changed, 166 insertions, 3 deletions
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC721Transfer.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC721Transfer.sol index c170917ea..e00e43889 100644 --- a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC721Transfer.sol +++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC721Transfer.sol @@ -19,17 +19,179 @@ pragma solidity ^0.4.24; pragma experimental ABIEncoderV2; +import "./mixins/MAuthorizable.sol"; import "../../utils/LibBytes/LibBytes.sol"; -import "../../tokens/ERC721Token/ERC721Token.sol"; import "./libs/LibTransferErrors.sol"; contract MixinERC721Transfer is - LibTransferErrors + LibTransferErrors, + MAuthorizable { using LibBytes for bytes; bytes4 constant SAFE_TRANSFER_FROM_SELECTOR = bytes4(keccak256("safeTransferFrom(address,address,uint256,bytes)")); - + /// @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 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 | | 3 * 32 | function parameters: | + // | | 4 | 12 + 20 | 1. token address | + // | | 36 | | 2. tokenId | + // | | 68 | | 3. offset to receiverData (*) | + // | Data | | | receiverData: | + // | | 100 | 32 | receiverData Length | + // | | 132 | ** | receiverData Contents | + + // We construct calldata for the `token.safeTransferFrom` ABI. + // The layout of this calldata is in the table below. + // + // | Area | Offset | Length | Contents | + // |----------|--------|---------|-------------------------------------| + // | Header | 0 | 4 | function selector | + // | Params | | 4 * 32 | function parameters: | + // | | 4 | | 1. from | + // | | 36 | | 2. to | + // | | 68 | | 3. tokenId | + // | | 100 | | 4. offset to receiverData (*) | + // | Data | | | receiverData: | + // | | 132 | 32 | receiverData Length | + // | | 164 | ** | receiverData Contents | + + // bytes4 safeTransferFromSelector = SAFE_TRANSFER_FROM_SELECTOR; + // bool success; + assembly { + // There exists only 1 of each token. + // require(amount == 1, "INVALID_AMOUNT") + if sub(calldataload(100), 1) { + // Revert with `Error("INVALID_AMOUNT")` + mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000) + mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000) + mstore(64, 0x0000000e494e56414c49445f414d4f554e540000000000000000000000000000) + mstore(96, 0) + revert(0, 100) + } + + // Require assetData to be at least 132 bytes + let offset := calldataload(4) + if lt(calldataload(add(offset, 4)), 132) { + // Revert with `Error("ASSET_DATA_TO_SHORT")` + mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000) + mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000) + mstore(64, 0x0000001341535345545f444154415f544f5f53484f5254000000000000000000) + mstore(96, 0) + revert(0, 100) + } + + /////// Setup State /////// + // `cdStart` is the start of the calldata for + // `token.safeTransferFrom` (equal to free memory ptr). + let cdStart := mload(64) + // `dataAreaLength` is the total number of words + // needed to store `receiverData` + // As-per the ABI spec, this value is padded up to + // the nearest multiple of 32, + // and includes 32-bytes for length. + // It's calculated as folows: + // - Unpadded length in bytes = `mload(receiverData) + 32` + // - Add 31 to convert rounding down to rounding up. + // Combined with the previous and this is `63`. + // - Round down to nearest multiple of 32 by clearing + // bits 0x1F. This is done with `and` and a mask. + + /////// 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, 0xb88d4fde00000000000000000000000000000000000000000000000000000000) + + /////// Setup Params Area /////// + // Each parameter is padded to 32-bytes. + // The entire Params Area is 128 bytes. + // Notes: + // 1. A 20-byte mask is applied to addresses + // to zero-out the unused bytes. + // 2. The offset to `receiverData` is the length + // of the Params Area (128 bytes). + + let length := calldataload(add(offset, 104)) + let token := calldataload(add(offset, 40)) + + // Round length up to multiple of 32 + length := and(add(length, 31), 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFE0) + + // Copy `from` and `to` + calldatacopy(add(cdStart, 4), 36, 64) + + // TokenId + mstore(add(cdStart, 68), calldataload(add(offset, 72))) + + // Offset to receiverData + mstore(add(cdStart, 100), 128) + + // receiverData (including length) + calldatacopy(add(cdStart, 132), add(offset, 104), add(length, 32)) + + /////// Call `token.safeTransferFrom` using the calldata /////// + let success := call( + gas, // forward all gas + token, // call address of token contract + 0, // don't send any ETH + cdStart, // pointer to start of input + add(length, 164), // length of input + 0, // write output to null + 0 // output size is 0 bytes + ) + + if iszero(success) { + // Revert with `Error("TRANSFER_FAILED")` + mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000) + mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000) + mstore(64, 0x0000000f5452414e534645525f4641494c454400000000000000000000000000) + mstore(96, 0) + revert(0, 100) + } + } + } + /// @dev Internal version of `transferFrom`. /// @param assetData Encoded byte array. /// @param from Address to transfer asset from. diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibTransferErrors.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibTransferErrors.sol index 88187f196..98bca31b2 100644 --- a/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibTransferErrors.sol +++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibTransferErrors.sol @@ -25,4 +25,5 @@ contract LibTransferErrors { /// Transfer errors /// string constant INVALID_AMOUNT = "INVALID_AMOUNT"; // Transfer amount must equal 1. string constant TRANSFER_FAILED = "TRANSFER_FAILED"; // Transfer failed. + string constant ASSET_DATA_TO_SHORT = "ASSET_DATA_TO_SHORT"; // Asset data to short } |