Build your own protocol

In the following sections, we will guide you through the process of building your own IBC protocol. We will cover how to establish a channel between two chains, send and receive packets and how to handle timeouts and acknowledgements.

Entrypoints

To get an IBC-enabled contract, you need to implement a few IBC-specific entrypoints.

Three for the channel lifecycle:

#[cfg_attr(not(feature = "library"), entry_point)]
pub fn ibc_channel_open(
    deps: DepsMut,
    env: Env,
    msg: IbcChannelOpenMsg
) -> StdResult<IbcChannelOpenResponse> {
    Ok(None)
}
 
#[cfg_attr(not(feature = "library"), entry_point)]
pub fn ibc_channel_connect(
    deps: DepsMut,
    env: Env,
    msg: IbcChannelConnectMsg,
) -> StdResult<IbcBasicResponse> {
    Ok(IbcBasicResponse::new())
}
 
#[cfg_attr(not(feature = "library"), entry_point)]
pub fn ibc_channel_close(
    deps: DepsMut,
    env: Env,
    msg: IbcChannelCloseMsg,
) -> StdResult<IbcBasicResponse> {
    Ok(IbcBasicResponse::new())
}

And three for the packet lifecycle:

#[cfg_attr(not(feature = "library"), entry_point)]
pub fn ibc_packet_receive(
    deps: DepsMut,
    env: Env,
    msg: IbcPacketReceiveMsg,
) -> StdResult<IbcReceiveResponse> {
    Ok(IbcReceiveResponse::new(b""))
}
 
#[cfg_attr(not(feature = "library"), entry_point)]
pub fn ibc_packet_ack(
    deps: DepsMut,
    env: Env,
    msg: IbcPacketAckMsg,
) -> StdResult<IbcBasicResponse> {
    Ok(IbcBasicResponse::new())
}
 
#[cfg_attr(not(feature = "library"), entry_point)]
pub fn ibc_packet_timeout(
    _deps: DepsMut,
    _env: Env,
    _msg: IbcPacketTimeoutMsg,
) -> StdResult<IbcBasicResponse> {
    Ok(IbcBasicResponse::new())
}

We will explain what these are for in the next sections, but it is important to understand that you need to implement all of these entrypoints to get a working IBC contract. You can always return errors in some of them if that makes sense for your protocol, but you need to have them all.

Basic concepts Channel lifecycle