RPCIEGE - Skirmish 9

It's time to have a go at Skirmish 9 of the Soroban RPCiege!
For a short recap on what RPCiege is, see my previous post.

Skirmish 9 is about upgrading our contract.

Our mission:

We're pointed to the game contract, which is a deployer: it will deploy a contract for us to work with.
Let's call it, then see what we have to work with.

(You'll notice I took the lazy route with the salt again: copied the example value and adjusted it slightly. You'll have to generate your own unique one)
A little spoiler: after you've used the deploy function, you don't need to do anything with the deployer contract anymore.

Now that we have a contract, let's see what it does.
Last time we used -h to let soroban-cli show us information about the functions. This time, we'll use fetch

soroban contract fetch --network rpciege --id <your_contract_id_here> -o skirmish_9.wasm

This lets soroban-sli download the contract (through the specified RPC server) and store it in the specified -o file.

Then, we can inspect it:

soroban contract inspect --wasm skirmish_9.wasm

It's not as pretty as -h, but it does show all functions and their parameters at once.
Here we can see that the run function doesn't take any parameters, and that the upgrade_contract function takes one parameter, named hash. It takes a value of the types BytesN.
Luckily, soroban-cli will handle the conversion from String to BytesN for us.

If you've completed any of the other skirmishes, you may notice that there's no parameter for _nft_dest.
That means we can't claim those slick trading cards!

But you've probably connected the dots by now:

1. Contract with missing function parameter
2. Upgradable contract
3. ??
4. Profit!

Yes, you need to write a new contract now.
I'm not going to show the exact Rust code to use.
You could write one from scratch, or modify one you have. I don't know if it must have a function called run, but I named my function that.
I know it doesn't need to do anything, but you can be creative.
Just make sure it also has a parameter _nft_dest.
Now soroban contract build it, and let's get to upgrading.

To upgrade a contract, three things are needed:

1. An existing contract with code to upgrade itself (already provided)
2. A new wasm thats been installed on the ledger. (It doesn't have to be deployed though)
3. A hash to identify which wasm you want to use.

To install the wasm of your new upgrade, you can use:

soroban contract install --network rpciege --source <your identity> --wasm <path_to_your_wasm>

The install command will return you the hash of your installed contract.

So, we finally reach the conclusion:

1. You have a target contract, with an upgrade_contract function that takes a --hash argument.
2. You also have your own contract, installed, and its hash

Happy cieging!