Summary

PoC implementation for multihop.

IBC specification

• ics-033
  • Might need updates with changes we make
• ics-004
  • Search for multihop to understand on-chain handling
• ics-003
  • Search for multihop to understand on-chain handling

ibc-go PoC implementation

• Repository
• Includes new/changed protos (to include and use in some ibc-proto-rs branch)
• Might need to make changes (forked Dec 2023)

Protos

• Update ibc-proto-rs (@romac)
  • Multi-hop protos cosmos/ibc-proto-rs#206

Channel CLIs

• tx chan-open-init
  • Add support for multiple connection hops in tx chan-open-init #3950
• tx chan-open-try
  • Add support for multiple connection hops in tx chan-open-try #3987
• tx chan-open-ack
  • Add support for multiple connection hops in tx chan-open-ack  #4049
• tx chan-open-confirm
  • Add support for multiple connection hops in tx chan-open-confirm #4055
• create channel
  • Add support for multiple connection hops in create channel command #4062

Hermes

• Add multihop support to packet relaying
  • Add multihop support to packet relaying #4084

Lesser priority

• Add multihop support to tx chan-close-init
• Add multihop support to tx chan-close-confirm
• Add multihop support to tx ft-transfer

Task overview

• Implement MultihopProof
• Implement GenerateMultihopProof
• Should look at the spec and figure out the best approach for Hermes, write a multihop ADR
  • e.g. calcProofHeights should actually be something like updateClientsAndGetProofHeights
  • queryIntermediateProofs could be done in parallel with updateClientsAndGetProofHeights
• Add multihop proofs to:
  • chann_open_try
  • ack
  • confirm
  • close
  • close_confirm
  • recv_packet
  • acknowledgement
  • timeout
  • timeout_on_close,
• Implement ChanCloseFrozen
  • Monitor spanned client states
  • Trigger ChanCloseFrozen to both channel ends
• Events - need to adapt as some change to include multihop connections (e.g. send_packet, etc)
• Upgrade a channel from single-hop to multi-hop, perform all required checks when upgrading (ie. that the connections are open, etc.)

For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate milestone (priority) applied
• Appropriate contributors tagged
• Contributor assigned/self-assigned