upgrade-func.md

Lack of upgrade function

Configuration

• detector id: upgrade-func
• severity: low

Description

Contracts may need the upgrade function, Rustle will check if such an interface exists in the contract.

Without an upgrade function, the contract cannot be upgraded and contract states cannot be migrated.

Sample code

Here is a sample of an upgrade function.

// https://github.com/NearDeFi/burrowland/blob/687d72ab6c158b3160dc31d6840471a687eff9d5/contract/src/upgrade.rs#L46
mod upgrade {
    use near_sdk::{require, Gas};

    use super::*;
    use near_sys as sys;

    const GAS_TO_COMPLETE_UPGRADE_CALL: Gas = Gas(Gas::ONE_TERA.0 * 10);
    const GAS_FOR_GET_CONFIG_CALL: Gas = Gas(Gas::ONE_TERA.0 * 5);
    const MIN_GAS_FOR_MIGRATE_STATE_CALL: Gas = Gas(Gas::ONE_TERA.0 * 10);

    /// Self upgrade and call migrate, optimizes gas by not loading into memory the code.
    /// Takes as input non serialized set of bytes of the code.
    #[no_mangle]
    pub extern "C" fn upgrade() {
        env::setup_panic_hook();
        let contract: Contract = env::state_read().expect("ERR_CONTRACT_IS_NOT_INITIALIZED");
        contract.assert_owner();
        let current_account_id = env::current_account_id().as_bytes().to_vec();
        let migrate_method_name = b"migrate_state".to_vec();
        let get_config_method_name = b"get_config".to_vec();
        let empty_args = b"{}".to_vec();
        unsafe {
            sys::input(0);
            let promise_id = sys::promise_batch_create(
                current_account_id.len() as _,
                current_account_id.as_ptr() as _,
            );
            sys::promise_batch_action_deploy_contract(promise_id, u64::MAX as _, 0);
            // Gas required to complete this call.
            let required_gas =
                env::used_gas() + GAS_TO_COMPLETE_UPGRADE_CALL + GAS_FOR_GET_CONFIG_CALL;
            require!(
                env::prepaid_gas() >= required_gas + MIN_GAS_FOR_MIGRATE_STATE_CALL,
                "Not enough gas to complete state migration"
            );
            let migrate_state_attached_gas = env::prepaid_gas() - required_gas;
            // Scheduling state migration.
            sys::promise_batch_action_function_call(
                promise_id,
                migrate_method_name.len() as _,
                migrate_method_name.as_ptr() as _,
                empty_args.len() as _,
                empty_args.as_ptr() as _,
                0 as _,
                migrate_state_attached_gas.0,
            );
            // Scheduling to return config after the migration is completed.
            //
            // The upgrade method attaches it as an action, so the entire upgrade including deploy
            // contract action and migration can be rolled back if the config view call can't be
            // returned successfully. The view call deserializes the state and deserializes the
            // config which contains the owner_id. If the contract can deserialize the current config,
            // then it can validate the owner and execute the upgrade again (in case the previous
            // upgrade/migration went badly).
            //
            // It's an extra safety guard for the remote contract upgrades.
            sys::promise_batch_action_function_call(
                promise_id,
                get_config_method_name.len() as _,
                get_config_method_name.as_ptr() as _,
                empty_args.len() as _,
                empty_args.as_ptr() as _,
                0 as _,
                GAS_FOR_GET_CONFIG_CALL.0,
            );
            sys::promise_return(promise_id);
        }
    }
}