Add 668 functions to solo machine

[colin-axner]

Summary

In preparation for the additional functions to the client state interface, #668, add:

• VerifyClientMsg
• CheckForMisbehaviour
• UpdateStateOnMisbehaviour
• UpdateState

for solomachine

Recommended splits:

PR 1

Rename Misbehaviour to DuplicateSignatureHeader

Decision to maintain existing naming: See comment

PR 2

Rename checkHeader to VerifyClientMsg.

Add functionality to account for Misbehaviour. Essentially verifying signatures twice. Code between checkHeader and verifySignatureAndData can be deduplicated.

Add a switch

switch header.(type) {
case NormalHeader:
   // https://github.com/cosmos/ibc-go/blob/c378ff3b9e637dbae171d2c5129d966b468a2305/modules/light-clients/06-solomachine/types/update.go#L40-#L59)
    data := normal header update code
     checkSignature(data)
     
case Misbehaviour:
    // https://github.com/cosmos/ibc-go/blob/c378ff3b9e637dbae171d2c5129d966b468a2305/modules/light-clients/06-solomachine/types/misbehaviour_handle.go#L37-#L44
    checkSignature(sig1)
    checkSignature(sig2)
   
default:
    return error
}

PR 3

Rename update to UpdateState

PR 4

CheckForMisbehaviour returns true (it passed VerifyClientMsg check)

PR 5

UpdateStateOnMisbehaviour set client state in state to be frozen

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For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged/assigned

[damiannolan]

I'll pick up PR 1 here to make a start!

[damiannolan]

I've got started with PR 2. @seantking I see you assigned but did you start any task? Happy to pair up on the work later today, let me know if you've started anything! :)

[colin-axner]

closed by the linked pr's!

[colin-axner]

great work @damiannolan