IBC Token Transfer functionality

[adizere]

Context

Token transfer allows fungible token transfers between two IBC chains. Token transfer is one of the most valuable & straightforward application of IBC.

Further reading

Token transfer spec ICS20: ics-020-fungible-token-transfer
TLA+ spec for ICS20 fungible-token-transfer

Dependencies

The implementation of token transfers depends directly on:

• ICS04: ics-004-channel-and-packet-semantics

For complete implementation & acceptance:

• ICS02: ics-002-client-semantics
• ICS03: ics-003-connection-semantics
• ICS26: ics-026-routing-module
• ICS18: ics-018-relayer-algorithms
• model-based testing (MBT) harness

Acceptance criteria

Component	Functionality	Criteria	Status
Module	Token Transfer App Handlers	Impl & unit tests	partial
Module	Token Transfer App Handlers	MBT tests	[ ]
Module	Token Transfer App Handlers	TLA+ spec	[X]
Module	Token Transfer App Handlers	Integration tests with mock chain	[ ]
CLI	Token Transfer command (packet send)	Impl & end-to-end tests	[X]
CLI	Token Transfer command (packet recv, ack, timeouts)	Impl & end-to-end tests	partial

Related issues

The following ongoing issues provide a more fine-grained perspective on the different parts of IBC client functionality:

• Handler for Packets (ICS 004) Handler for Packets (ICS 004) cosmos/ibc-rs#101
• Introduce (PortId, ChannelId) domain type Introduce (PortId, ChannelId) domain type cosmos/ibc-rs#84
• Relay for all paths defined in the configuration Relay for all paths defined in the configuration #748
• Add CI test for the relayer loop Add CI test for the relayer loop #708
• Add test for MsgTimeout in CI Add test for MsgTimeout in CI #707