Implement Capability{Reader,Keeper} traits

[hu55a1n1]

Crate

ibc

Summary

The current implementation of ChannelReader::authenticated_capability() seems to assume a source authentication model. Also, the implementation is incomplete.

Proposal

Define Capability{Reader,Keeper} traits and add other related methods from ICS05. Make CapabilityReader a super-trait of ChannelReader and PortReader.

trait CapabilityReader {
    fn claim(name: String, capability: CapabilityKey);

    fn authenticate(&self, name: impl AsRef<str>, capability: &CapabilityKey) -> Result<(), Error>;
    
    // ...
}

pub trait PortReader: CapabilityReader {
    fn authenticate_capability(&self, port_id: PortId, capability: &CapabilityKey) -> Result<(), Error> {
        self.authenticate(Path::Ports(port_id), capability)
    }
    
    // ...
}

Acceptance Criteria

• Implement all capability related methods from ICS05.
• Allow lib users to decide if they'd like to opt for an object-capabilities model or source-authentication model.

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