Core Libraries
CoW Protocol employs specialized libraries designed for gas efficiency and security, using low-level optimizations where appropriate.
GPv2Order
Defines the complete order structure and provides utilities for order management.
Data Structure
struct Data {
IERC20 sellToken;
IERC20 buyToken;
address receiver;
uint256 sellAmount;
uint256 buyAmount;
uint32 validTo;
bytes32 appData;
uint256 feeAmount;
bytes32 kind;
bool partiallyFillable;
bytes32 sellTokenBalance;
bytes32 buyTokenBalance;
}
Key Functions
hash(Data memory order) - Computes EIP-712 digest for signingactualReceiver(Data memory order) - Resolves recipient address (handles zero-address as owner)packOrderUidParams() - Encodes 56-byte UID (32-byte digest + 20-byte owner + 4-byte timestamp)extractOrderUidParams() - Decodes UID components
Pre-computed Constants
bytes32 constant KIND_SELL = keccak256("sell");
bytes32 constant KIND_BUY = keccak256("buy");
bytes32 constant BALANCE_ERC20 = keccak256("erc20");
bytes32 constant BALANCE_EXTERNAL = keccak256("external");
bytes32 constant BALANCE_INTERNAL = keccak256("internal");
GPv2Trade
Handles compact settlement representation through a flags field that encodes order parameters into a single uint256 value.
Flag Encoding
| Bits | Field | Values |
|---|
| 0 | Order kind | 0 = sell, 1 = buy |
| 1 | Fill type | 0 = fill-or-kill, 1 = partially fillable |
| 2-3 | Sell token balance | 00 = ERC20, 01 = external, 10 = internal |
| 4 | Buy token balance | 0 = ERC20, 1 = internal |
| 5-6 | Signing scheme | 00 = EIP-712, 01 = eth_sign, 10 = EIP-1271, 11 = PreSign |
0x00 represents the most common case: a fill-or-kill sell order by an externally owned account using EIP-712 signatures.
Key Functions
extractOrder() - Converts trade data into a full order structextractFlags() - Unpacks flags into separate order parameters
GPv2Interaction
Enables arbitrary contract calls during settlement using inline assembly for gas optimization.
Data Structure
struct Data {
address target;
uint256 value;
bytes callData;
}
Key Functions
execute(Data calldata interaction) - Performs the contract interactionselector(Data calldata interaction) - Extracts 4-byte function selector
Settlement Phases
Interactions run at three distinct phases:
- Pre-settlement - Setup operations like approvals
- Intra-settlement - Liquidity transformations after input transfers
- Post-settlement - Cleanup tasks like token unwrapping
GPv2Signing
Supports four signature schemes:
| Scheme | Description |
|---|
| EIP-712 | Standard typed data signing |
| eth_sign | Legacy signing with message prefix |
| EIP-1271 | Smart contract signature verification |
| PreSign | On-chain pre-authorization |
Key Features
- Careful memory management to avoid unnecessary copies
- Extensive use of
calldata instead of memory for read-only data
- Domain separator includes contract address for replay protection
- Pre-computed hash constants for common types
Last modified on March 4, 2026
