axelar-cgp-sui

Module 0xa1::gateway

Implementation of the Axelar Gateway for Sui Move.

This code is based on the following:

• When call approvals is sent to Sui, it targets an object and not a module;
• To support cross-chain messaging, a Channel object has to be created;
• Channel can be either owned or shared but not frozen;
• Module developer on the Sui side will have to implement a system to support messaging;
• Checks for uniqueness of approvals should be done through Channels to avoid big value storage;

I. Sending call approvals

A approval is sent through the send function, a Channel is supplied to determine the source -> ID. Event is then emitted and Axelar network can operate

II. Receiving call approvals

Approval bytes and signatures are passed into create function to generate a CallApproval object.

• Signatures are checked against the known set of signers.
• CallApproval bytes are parsed to determine: source, destination_chain, payload and destination_id
• destination_id points to a Channel object

Once created, CallApproval needs to be consumed. And the only way to do it is by calling consume_call_approval function and pass a correct Channel instance alongside the CallApproval.

• CallApproval is checked for uniqueness (for this channel)
• CallApproval is checked to match the Channel.id

The Gateway object uses a versioned field to support upgradability. The current implementation uses Gateway_v0.

• Resource Gateway
• Resource CreatorCap
• Constants
• Function init
• Function setup
• Function approve_messages
• Function rotate_signers
• Function prepare_message
• Function send_message
• Function is_message_approved
• Function is_message_executed
• Function take_approved_message
• Function version_control

use 0x1::ascii;
use 0x1::vector;
use 0x2::bcs;
use 0x2::clock;
use 0x2::object;
use 0x2::table;
use 0x2::transfer;
use 0x2::tx_context;
use 0x2::versioned;
use 0xa1::auth;
use 0xa1::bytes32;
use 0xa1::channel;
use 0xa1::gateway_v0;
use 0xa1::message_status;
use 0xa1::message_ticket;
use 0xa1::weighted_signers;
use 0xb0::version_control;

Resource Gateway

struct Gateway has key

Fields

id: object::UID

inner: versioned::Versioned

Resource CreatorCap

struct CreatorCap has store, key

Fields

id: object::UID

Constants

const VERSION: u64 = 0;

Function init

Init the module by giving a CreatorCap to the sender to allow a full setup.

fun init(ctx: &mut tx_context::TxContext)

Implementation

fun init(ctx: &mut TxContext) {
    let cap = CreatorCap {
        id: object::new(ctx),
    };

    transfer::transfer(cap, ctx.sender());
}

Function setup

Setup the module by creating a new Gateway object.

entry fun setup(cap: gateway::CreatorCap, operator: address, domain_separator: address, minimum_rotation_delay: u64, previous_signers_retention: u64, initial_signers: vector<u8>, clock: &clock::Clock, ctx: &mut tx_context::TxContext)

Implementation

entry fun setup(
    cap: CreatorCap,
    operator: address,
    domain_separator: address,
    minimum_rotation_delay: u64,
    previous_signers_retention: u64,
    initial_signers: vector<u8>,
    clock: &Clock,
    ctx: &mut TxContext,
) {
    let CreatorCap { id } = cap;
    id.delete();

    let inner = versioned::create(
        VERSION,
        gateway_v0::new(
            operator,
            table::new(ctx),
            auth::setup(
                bytes32::new(domain_separator),
                minimum_rotation_delay,
                previous_signers_retention,
                utils::peel!(
                    initial_signers,
                    |bcs| weighted_signers::peel(bcs),
                ),
                clock,
                ctx,
            ),
            version_control(),
        ),
        ctx,
    );

    // Share the gateway object for anyone to use.
    transfer::share_object(Gateway {
        id: object::new(ctx),
        inner,
    });
}

Function approve_messages

The main entrypoint for approving Axelar signed messages. If proof is valid, message approvals are stored in the Gateway object, if not already approved before. This method is only intended to be called via a Transaction Block, keeping more flexibility for upgrades.

entry fun approve_messages(self: &mut gateway::Gateway, message_data: vector<u8>, proof_data: vector<u8>)

Implementation

entry fun approve_messages(
    self: &mut Gateway,
    message_data: vector<u8>,
    proof_data: vector<u8>,
) {
    let value = self.value_mut!(b"approve_messages");
    value.approve_messages(message_data, proof_data);
}

Function rotate_signers

The main entrypoint for rotating Axelar signers. If proof is valid, signers stored on the Gateway object are rotated. This method is only intended to be called via a Transaction Block, keeping more flexibility for upgrades.

entry fun rotate_signers(self: &mut gateway::Gateway, clock: &clock::Clock, new_signers_data: vector<u8>, proof_data: vector<u8>, ctx: &tx_context::TxContext)

Implementation

entry fun rotate_signers(
    self: &mut Gateway,
    clock: &Clock,
    new_signers_data: vector<u8>,
    proof_data: vector<u8>,
    ctx: &TxContext,
) {
    let value = self.value_mut!(b"rotate_signers");
    value.rotate_signers(
        clock,
        new_signers_data,
        proof_data,
        ctx,
    )
}

Function prepare_message

Prepare a MessageTicket to call a contract on the destination chain.

public fun prepare_message(channel: &channel::Channel, destination_chain: ascii::String, destination_address: ascii::String, payload: vector<u8>): message_ticket::MessageTicket

Implementation

public fun prepare_message(
    channel: &Channel,
    destination_chain: String,
    destination_address: String,
    payload: vector<u8>,
): MessageTicket {
    message_ticket::new(
        channel.to_address(),
        destination_chain,
        destination_address,
        payload,
        VERSION,
    )
}

Function send_message

Submit the MessageTicket which causes a contract call by sending an event from an authorized Channel.

public fun send_message(self: &gateway::Gateway, message: message_ticket::MessageTicket)

Implementation

public fun send_message(
    self: &Gateway,
    message: MessageTicket,
) {
    let value = self.value!(b"send_message");
    value.send_message(message, VERSION);
}

Function is_message_approved

public fun is_message_approved(self: &gateway::Gateway, source_chain: ascii::String, message_id: ascii::String, source_address: ascii::String, destination_id: address, payload_hash: bytes32::Bytes32): bool

Implementation

public fun is_message_approved(
    self: &Gateway,
    source_chain: String,
    message_id: String,
    source_address: String,
    destination_id: address,
    payload_hash: Bytes32,
): bool {
    let value = self.value!(b"is_message_approved");
    value.is_message_approved(
        source_chain,
        message_id,
        source_address,
        destination_id,
        payload_hash,
    )
}

Function is_message_executed

public fun is_message_executed(self: &gateway::Gateway, source_chain: ascii::String, message_id: ascii::String): bool

Implementation

public fun is_message_executed(
    self: &Gateway,
    source_chain: String,
    message_id: String,
): bool {
    let value = self.value!(b"is_message_executed");
    value.is_message_executed(source_chain, message_id)
}

Function take_approved_message

To execute a message, the relayer will call take_approved_message to get the hot potato ApprovedMessage object, and then trigger the app’s package via discovery.

public fun take_approved_message(self: &mut gateway::Gateway, source_chain: ascii::String, message_id: ascii::String, source_address: ascii::String, destination_id: address, payload: vector<u8>): channel::ApprovedMessage

Implementation

public fun take_approved_message(
    self: &mut Gateway,
    source_chain: String,
    message_id: String,
    source_address: String,
    destination_id: address,
    payload: vector<u8>,
): ApprovedMessage {
    let value = self.value_mut!(b"take_approved_message");
    value.take_approved_message(
        source_chain,
        message_id,
        source_address,
        destination_id,
        payload,
    )
}

Function version_control

fun version_control(): version_control::VersionControl

Implementation

fun version_control(): VersionControl {
    version_control::new(
        vector [
            // Version 0
            vector [
                b"approve_messages",
                b"rotate_signers",
                b"is_message_approved",
                b"is_message_executed",
                b"take_approved_message",
                b"send_message",
            ].map!(|function_name| function_name.to_ascii_string())
        ]
    )
}