Merge pull request #877 from 0xProject/feature/contracts/removeERC721Callback

Removed receiverData and `onReceive` callback from ERC721 proxy.

1 files changed, 22 insertions, 74 deletions

diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol
index 1f9958b43..53f5a14e0 100644
--- a/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol
@@ -26,7 +26,7 @@ contract ERC721Proxy is
     MixinAuthorizable
 {
     // Id of this proxy.
-    bytes4 constant internal PROXY_ID = bytes4(keccak256("ERC721Token(address,uint256,bytes)"));
+    bytes4 constant internal PROXY_ID = bytes4(keccak256("ERC721Token(address,uint256)"));
 
     // solhint-disable-next-line payable-fallback
     function () 
@@ -83,19 +83,15 @@ contract ERC721Proxy is
                 // 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:                |
+                // | Params   |        | 2 * 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.
@@ -103,14 +99,10 @@ contract ERC721Proxy is
                 // | Area     | Offset | Length  | Contents                            |
                 // |----------|--------|---------|-------------------------------------|
                 // | Header   | 0      | 4       | function selector                   |
-                // | Params   |        | 4 * 32  | function parameters:                |
+                // | Params   |        | 3 * 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               |
 
                 // There exists only 1 of each token.
                 // require(amount == 1, "INVALID_AMOUNT")
@@ -122,76 +114,32 @@ contract ERC721Proxy is
                     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("LENGTH_GREATER_THAN_131_REQUIRED")`
-                    mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
-                    mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
-                    mstore(64, 0x000000204c454e4754485f475245415445525f5448414e5f3133315f52455155)
-                    mstore(96, 0x4952454400000000000000000000000000000000000000000000000000000000)
-                    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)
+                mstore(0, 0x23b872dd00000000000000000000000000000000000000000000000000000000)
                 
                 /////// 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, 136))
-                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, 136), add(length, 32))
-                
-                /////// Call `token.safeTransferFrom` using the calldata ///////
+                // We copy the fields `from` and `to` in bulk
+                // from our own calldata to the new calldata.
+                calldatacopy(4, 36, 64)
+
+                // Copy `tokenId` field from our own calldata to the new calldata.
+                let assetDataOffset := calldataload(4)
+                calldatacopy(68, add(assetDataOffset, 72), 32)
+
+                /////// Call `token.transferFrom` using the calldata ///////
+                let token := calldataload(add(assetDataOffset, 40))
                 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
+                    gas,            // forward all gas
+                    token,          // call address of token contract
+                    0,              // don't send any ETH
+                    0,              // pointer to start of input
+                    100,            // length of input
+                    0,              // write output to null
+                    0               // output size is 0 bytes
                 )
                 if success {
                     return(0, 0)