Introduce upper limit for settle_timeout

[LefterisJP]

Problem Definition

This is not a really serious problem, but we should also think of introducing an upper limit for the contract's settle_timeout property.

The only reason why we would need to do that is to protect users from themselves, by not letting them enter a settle_timeout close to 2**256 - 1 and then have either this or this modifier check overflow and have their channel botched with the tokens trapped in there forever.

Solution

Provide an upper limit for settle_timeout and enforce it in the contract.

Tasklist

• Provide upper limit for settle timeout
• Make test for that value
• Add a changelog entry.

[ulope]

Anything above a couple million to tens of millions of blocks (~ 1 - 10 year(s) with 20s blocks) could probably be considered "forever" for most practical use cases.

[hackaugusto]

Is #863 enough or do you want to add a check in the smart contract code?

[LefterisJP]

I want it in the smart contracts. It's an easy thing to add.