🐬Message Dispatching using Yaru and Yaho

For relaying arbitrary message between Ethereum/Goerli and Gnosis Chain, several contracts need to be deployed on top of the current AMB deployments: Yaho, Yaru, AMB Message Relay, AMB Adapter, and Hashi. The addresses from this article are for Goerli <-> Gnosis Chain.

Prerequisite

For Goerli->Gnosis Direction:

1. Deploy Yaho on Goerli, and Yaru on Gnosis Chain, with constructor _hashi: Hashi address on Gnosis Chain, _yaho: Yaho address on Goerli, _chainId: 5.

2. Optional: Deploy Hashi Module for Safe that will be called by Yaru, i.e. Safe on Gnosis Chain.

3. Deploy AMB Message Relay on Goerli, with constructor _amb: AMB address on Goerli, _yaho: Yaho address on Goerli.

4. Deploy AMB Adapter on Gnosis Chain, with constructor _amb: AMB address on Gnosis Chain, _reporter: AMB Message Relay on Goerli, _chainId: bytes32(5) .

In the current deployment, gas is added as a parameter in dispatchMessagesToAdapters() to justify the amb's gas requirement. It is not added into the official hashi code at the moment as it might raise incompatibility issue for other adapters. Please be aware that these contracts might be changed anytime.

Workflow: Ethereum -> Gnosis Chain

• User calls Yaho.dispatchMessagesToAdapters. Example

• Yaho calls AMB Message Relay relayMessages which will eventually calls storeHashes from AMB Adapter on Gnosis Chain.

• AMB Message Relay calls AMB requireToPassMessage, and the message will be relayed to AMB on Gnosis Chain.

• Once the AMB Adapter storeHashes is called, MessageDispatched event will be emitted and user need messageId data from the event. Example

• User calls Yaru.executeMessages with messageId and message as parameters. Example

Initiate Transaction

1. Create function calldata for the contract you want to call on Gnosis Chain.

const calldata = contractInterface.encodeFunctionData(function_name, parameters)

2. Optional: Create transaction calldata for Hashi Module.

This step is only needed when Safe is used.

const txData = hashi_module_interface.encodeFunctionData("executeTransaction", [
      ${contract_to_call_on_Gnosis_Chain},
      0,
      calldata,
      0,
]);

3. Create message with format below: With Safe:

const message =
{
    to: ${Hashi Module address},
    toChainId: 100 // Gnosis Chain,
    data: ${tx_data}
}

Without Safe:

const message =
{
    to: ${Contract address on Gnosis Chain},
    toChainId: 100 // Gnosis Chain,
    data: ${calldata}
}

4. Call Yaho.dispatchMessagesToAdapters([message],[AMB_Message_Relay_Address],[AMB_Adapter_Address]) using Safe or EOA.

5. Once the transaction is created, you need to collect messsage Id from MessageDispatched event emitted from Yaho.

Claim Transaction

After the message is relayed to Gnosis Chain by AMB bridge, you can proceed to claim your transaction. Make sure that your message is stored by checking if the AMB Adapter contract emits HashStored event with the correct message Id.

1. Call Yaru.executeMessages([message],[messageId],[Safe_from_Goerli or EOA from Goerli that calls Yaho],[AMB_Adapter_Address on Gnosis Chain])

Implement your hook

For a successful message execution to happen, the contract specified as message recipient on the destination chain must implement a hook to process correctly the message.data. The hook must revert unless the msg.sender matches the expected Yaru contract, Yaru.sender() matches the expected sender, and Yaru.adapters() matches the desired set of oracles that must have agreed on the reported hash.

Contract	Address	Chain
Yaho	0xC1289f49A1972E2C359a0647707a74E24ce73F8b	Goerli
AMB Message Relay	0x2433c921152B3dE133F96762a9b359D02dB34c93	Goerli
AMB Adapter for Message Relay	0xbA5B3f0643582E75AF252e7631dE62c046970167	GC
Yaru	0x171C1161bCde7adB32a9Ca92c412d39bE6F97C59	GC

Workflow: Gnosis Chain -> Ethereum

• User calls Yaho.dispatchMessagesToAdapters. Example

• Yaho calls AMB Message Relay relayMessages which will eventually calls storeHashes from AMB Adapter on Gnosis Chain.

• AMB Message Relay calls AMB requireToPassMessage, and UserRequestsForSignature event will be emitted.

• User calls AMB Helper contract's getSignature with the encodedData as parameters obtained from step3, the function will return signature.Tutorial

• User calls AMB on Goerli's executeSignature with encodedData and signature as parameters. The storeHashes from AMB Adapter will be called, MessageDispatched event will be emitted and user need messageId data from the event. Example

• User calls Yaru.executeMessages with messageId and message as parameters. Example

Contract	Address	Chain
Yaho	0x619360550f337bdA5A3A4709fEff2140c9577593	GC
AMB Message Relay	0x6796E267aa898464417BcD4D81690242bD39D68e	GC
AMB Helper	0xc7118ecF785871F08Feff5DE07d5F884b6199477	GC
AMB Adapter for Message Relay	0xBB448c841b1Ce6636aa804Bf97B1eBf9DF940f08	Goerli
Yaru	0x6Cdfa83b5b3e4eBc603fF12B8aAD893f7d7231d8	Goerli
Hashi	0x6a948572432818DeBbb04A0b82b6c12ec5Ca15B5	Goerli