Implement packet delay in packet relaying

[ancazamfir]

Crate

ibc-relayer and ibc-relayer-cli

Summary

To prevent certain attacks it is required that there is a delay between MsgUpdateClient and any packet messages: MsgRecvPacket, MsgAcknowledgment, MsgTimeout. This requires changes in the relayer that currently sends the Update Client in the same transaction as the packets. The lag should be obtained from the connection delay period parameter. Currently this is ignored if set by other relayer, always set to 0 by this relayer.

See cosmos/ibc#507 for more details

Note: This concerns the relayer functionality.
We'll cover packet delays in the IBC module in a separate issue.

Proposal

Will be detailed soon

---

For Admin Use

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