Check Expr length when converting to abi.Address

[jasonpaulos]

Right now abi.Address.set called with an Expr argument does not verify at runtime that the length of the argument is in fact 32 bytes:

pyteal/pyteal/ast/abi/address.py

Line 98 in 9edc6f5

return self.stored_value.store(value)

Without this verification, it's possible for the address variable to contain an invalid value.

There is some precedent for verifying this constraint, namely the checks that occur in abi.Uint.set when called with an Expr:

pyteal/pyteal/ast/abi/uint.py

Line 244 in 9edc6f5

def set(self: T, value: Union[int, Expr, "Uint", ComputedValue[T]]) -> Expr:

[barnjamin]

I guess we may also want to verify at runtime the transaction types are accurate?

[cusma]

@jasonpaulos @barnjamin would be good also to generate checks that abi.Bool value is actually Int(0) or Int(1).

[jasonpaulos]

I guess we may also want to verify at runtime the transaction types are accurate?

Yes, this is even more important.

edit: #427

@jasonpaulos @barnjamin would be good also to generate checks that abi.Bool value is actually Int(0) or Int(1).

We do this one correctly!

pyteal/pyteal/ast/abi/bool.py

Line 74 in 9edc6f5

Assert(self.stored_value.load() < Int(2)),

Though I wonder if it would be more consistent with the rest of the AVM to convert values greater than 1 to 1. This is how the && and || opcodes behave.

[ahangsu]

fixed by #432