Perform fee padding in a larger bit width of integers

[Shaptic]

What

Modify fee calculation to use 64-bit integers + tests for overflow.

Why

In situations where the resource fee padding causes the transaction fee to exceed its maximum value, it will overflow and create an invalid transaction, instead (i.e. one where the transaction fee is lower than the resource fee).

This code ensures that the padding is done in a higher bit width (i.e. with a u64) and then cast down to a u32.

Known limitations

• Releasing this is blocked heavily on Incorporate soroban-spec-tools dependency and remove all Soroban CLI references #68.
• I'm in the process of adding unit tests.

[leighmcculloch]

Would be great to add a test to catch the overflow too.

[Shaptic]

@dmkozh @leighmcculloch please have another look! The logic is still the same but it should be easier to read:

• first, pick the larger of tx fee and base inclusion fee + min resource fee, ensuring this fits in a u32
• then, bump that by 15% via the same int math
• finally, cap that at u32_max

And the tests should reflect checks to these three steps.

[mn13]

Hey guys, could you please explain some details why fee should fit 32 bits?

Why: with soroban 20.3.1 I tried to call soroban contract install with a 61 kb wasm in testnet and got error: Fee was too large 4946582915. After some investigation I found that error occurs in https://github.com/stellar/soroban-rpc/blob/main/cmd/crates/soroban-rpc/src/txn.rs#L321 because classic_tx_fee + simulation.min_resource_fee = 4946582915 or 494.6582915 XLM.
Why values that exceed U32_MAX is not allowed for fee? Does it mean that there is no way to install wasm in mainnet with soroban-cli?

[2opremio]

Hi @mn13 ! Thanks for reporting your problem. However, could you please create a separate ticket for it? Thanks!

[leighmcculloch]

The 32-bit size is limited by the protocol, so any change to the size is a protocol change for the Stellar network itself, and not just a change to the rpc, or another tool.

@mn13 The best place to discuss possible protocol changes is currently over on the stellar-protocol repo's discussion form, if you'd like to open an issue there: https://github.com/stellar/stellar-protocol/discussions