Parse denoms of incoming ICS-20 transfers

[anilhelvaci]

What is the Problem Being Solved?

When ics-20 transfers are received in an address hook (receiveUpcall), we should be able to tell the local denom for the token being received. For example, transfer/channel-0/transfer/channel-1/uatom. We must also handle the case for receiving token that are local to Agoric. Currently we cannot solve the problem of receiving BLD over multiple hops in a generic way, like transfer/channel-0/transfer/channel-1/uatom.

Description of the Design

@michaelfig came up with the idea that we can make a query to learn the ibc/ prefixed hash for a given trace information. Of course we need to handle the denoms that are native to Agoric.

The design is a standalone method placed under orchestration/src/exos/local-orchestration-account.js which accepts an VTransferIBCEvent.packet to extract transfer information including the denom and checks;

• Is this denom local to Agoric?
  • If the incoming denom is prefixed with source_port/source_channel that mean the base denom is local to receiving chain. See ICS-20 Spec
• If the incoming denom is not Agoric native, than query the hash that represents the voucher token in bank module