is there any way to check that user A owns spl token B inside solana contract? Maybe there is safe method to check it outside.
I need it to give some privileges to users, which own mine nfts. Users would write data to program only when they have nft.
To check the owner of an SPL token account from within a program, you'll have to deserialize it and check the owner field, ie:
use solana_program::{
account_info::next_account_info, account_info::AccountInfo, entrypoint,
entrypoint::ProgramResult, pubkey::Pubkey, program_pack::Pack,
};
use spl_token::state::Account;
entrypoint!(process_instruction);
const EXPECTED_OWNER: Pubkey = Pubkey::new_from_array([1; 32]);
fn process_instruction(
program_id: &Pubkey,
accounts: &[AccountInfo],
instruction_data: &[u8],
) -> ProgramResult {
let account_info_iter = &mut accounts.iter();
let spl_token_account_info = next_account_info(account_info_iter)?;
let spl_token_account_data = spl_token_account_info.try_borrow_data()?;
let spl_token_account = Account::unpack(&spl_token_account_data)?;
if spl_token_account.owner == EXPECTED_OWNER {
// your logic here
}
}
Note that I haven't tried to compile this, so use with caution!