Can invoke_signed Be Used in Solana Native Programs to Handle SPL Tokens for Staking?

Question

While reviewing the Solana codebase, I came across the invoke_signed function, which is commonly used for cross-program invocations. I'm particularly interested in understanding if it's possible to utilize invoke_signed within a Solana native program, such as the Stake program.

My goal is to explore the feasibility of implementing staking functionality in a Solana native program while using SPL (Solana Program Library) tokens as the staked assets. In essence, I would like to know if it's possible to call SPL token methods via invoke_signed or any other suitable method within a native program. This would involve the ability to add or subtract SPL tokens from a wallet in a staking context.

I would greatly appreciate any insights, recommendations, or references to relevant code examples or documentation that can shed light on this matter. If invoke_signed is not the appropriate approach for this use case, I would welcome suggestions on alternative methods to achieve the desired functionality within a Solana native program.

Answer 1

You can call a CPI to any Solana program, including the Token program which generally manages SPL tokens.

If you look into the source of a CPI call like token::mint_to(cpi_ctx, amount), you'll see that it uses solana_program::program::invoke_signed itself under the hood. Here's how the Anchor source calls the native mint_to ix from the token program:

pub fn mint_to<'info>(
    ctx: CpiContext<'_, '_, '_, 'info, MintTo<'info>>,
    amount: u64,
) -> Result<()> {
    let ix = spl_token::instruction::mint_to(
        &spl_token::ID,
        ctx.accounts.mint.key,
        ctx.accounts.to.key,
        ctx.accounts.authority.key,
        &[],
        amount,
    )?;
    solana_program::program::invoke_signed(
        &ix,
        &[
            ctx.accounts.to.clone(),
            ctx.accounts.mint.clone(),
            ctx.accounts.authority.clone(),
        ],
        ctx.signer_seeds,
    )
    .map_err(Into::into)
}

(https://docs.rs/anchor-spl/latest/src/anchor_spl/token.rs.html#64)

Answer 2

This is possible.

invoke - Used when you want to cpi into another program using your keypair(an onCurve address)

invoke_signed - used when you want to cpi into another program but you want your pda to sign instead.

Here is a link to invoke being used to create a token mint - https://github.com/solana-developers/program-examples/blob/bbe6a8d8a43302c233bf8ae9017c74e9f73dabea/tokens/nft-minter/native/program/src/instructions/create.rs#L60-L74

Here is a link to invoke_signed being used to call mpl to create the metadata account - https://github.com/solana-developers/program-examples/blob/bbe6a8d8a43302c233bf8ae9017c74e9f73dabea/tokens/pda-mint-authority/native/program/src/instructions/create.rs#L91-L119

invoke and invoke signed docs - https://docs.solana.com/developing/programming-model/calling-between-programs