Router Interfaces

Router Protocol provides the evm-gateway-contracts library to facilitate the development of cross-chain dApps.

Installation

Using Remix

If you're using Remix, you can import the contracts directly as shown in the examples below.

Using Hardhat

For Hardhat projects, install the package via npm, yarn or pnpm:

npm

npm install @routerprotocol/evm-gateway-contracts

pnpm

pnpm add @routerprotocol/evm-gateway-contracts

Yarn

yarn add @routerprotocol/evm-gateway-contracts

Gateway

The Router Gateway is deployed on all chains supported by Router Protocol and serves as the central communication point between chains.

IGateway

import "@routerprotocol/evm-gateway-contracts/contracts/IGateway.sol";

To develop cross-chain contracts, you should generally:

1. Import the IGateway.sol interface into all cross-chain contracts
2. Create a variable to store the Gateway contract address
3. Initialize it with the corresponding Gateway address of the given chain

This setup will be used later to call the iSend function.

iSend()

function iSend(
  uint256 version,
  uint256 routeAmount,
  string calldata routeRecipient,
  string calldata destChainId,
  bytes calldata requestMetadata,
  bytes calldata requestPacket
) external payable returns (uint256);

iSend is the function you'll call on the Gateway of the source chain to initiate a cross-chain message. Every contract that wants to make a cross-chain call needs to call it.

For a detailed description of each parameter, refer to the Router Protocol iSend documentation.

getRequestMetaData()

    function getRequestMetadata(
    uint64 destGasLimit,
    uint64 destGasPrice,
    uint64 ackGasLimit,
    uint64 ackGasPrice,
    uint128 relayerFees,
    uint8 ackType,
    bool isReadCall,
    string memory asmAddress
) public pure returns (bytes memory) {
    bytes memory requestMetadata = abi.encodePacked(
    destGasLimit,
    destGasPrice,
    ackGasLimit,
    ackGasPrice,
    relayerFees,
    ackType,
    isReadCall,
    asmAddress
    );
    return requestMetadata;
}

The getRequestMetadata function helps create the requestMetadata bytes object required for the iSend function call.

Here's an overview of the arguments:

Argument	Example Value	Description
destGasLimit	300000	Gas limit on destination chain
destGasPrice	100000000000	Gas price on destination chain
ackGasLimit	300000	Gas limit on source chain for ack
ackGasPrice	100000000000	Gas price on source chain for ack
relayerFees	10000000000	Relayer fees on Router chain
ackType	3	Acknowledge type
isReadCall	false	If the call is read-only
asmAddress	"0x"	Address for the additional security module

Alternatively, you can use ethers.js to encode the metadata:

const metadata = ethers.utils.solidityPack(
    ['uint64', 'uint64', 'uint64', 'uint64', 'uint128', 'uint8', 'bool', 'string'],
    [destGasLimit, destGasPrice, ackGasLimit, ackGasPrice, relayerFees, ackType, isReadCall, asmAddress]
);

For more information about encoding and the request metadata, see the Router metadata documentation.

IDapp

import "@routerprotocol/evm-gateway-contracts/contracts/IDapp.sol";

The IDapp interface consists of two main functions:

1. iReceive: The entry point for the cross-chain message on the destination chain
2. iAck: The entry point on the source chain to receive the acknowledgment

iReceive()

function iReceive(
    string memory requestSender,
    bytes memory packet,
    string memory srcChainId
  ) external returns (bytes memory)

iReceive is called by the Gateway on the destination chain.

For more information about iReceive, see the Router iReceive documentation.

iAck()

function iAck(
    uint256 requestIdentifier,
    bool execFlag,
    bytes memory execData
  ) external

iAck is called by the Gateway on the source chain.

For more information about iAck, see the Router iAck documentation.