Change host_height, host_timestamp return value to a Result in ClientReader, ConnectionReader, ChannelReader and ValidationContext

[DaviRain-Su]

Summary

For downstream implementation of ibc-rs interface, host_height, host_timestamp may be wrong, here we suggest to return a Result type.

Problem Definition

Proposal

Acceptance Criteria

change before is

fn host_height(&self) -> Height;
fn host_timestamp(&self) -> Timestamp;

change after is

fn host_height(&self) -> Result<Height, Error>;
fn host_timestamp(&self) -> Result<Timestamp, Error>;

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[plafer]

Could you provide an example scenario where it would be the case that the host cannot provide either its height or timestamp?

[DaviRain-Su]

Could you provide an example scenario where it would be the case that the host cannot provide either its height or timestamp?

For downstream implementers to construct Height and timestap here there is a Result type, for the construction of Height returns a Result, my suggestion is that the host_height function returns a Return type of Result. For host_timestamp is similar.

https://github.com/octopus-network/substrate-ibc/blob/6d49011521414b167f05d54bf586a825be4d9a5f/src/module/core/ics02_client.rs#L292