Reading Multiple Instructions
Solana allows us to take a peek at all of the instructions in the current transaction. We can store them in a variable and iterate over them. We can do many things with this, like checking for suspicious transactions.
use anchor_lang::{
prelude::*,
solana_program::{
sysvar,
serialize_utils::{read_pubkey,read_u16}
}
};
declare_id!("8DJXJRV8DBFjJDYyU9cTHBVK1F1CTCi6JUBDVfyBxqsT");
#[program]
pub mod cookbook {
use super::*;
pub fn read_multiple_instruction<'info>(ctx: Context<ReadMultipleInstruction>, creator_bump: u8) -> Result<()> {
let instruction_sysvar_account = &ctx.accounts.instruction_sysvar_account;
let instruction_sysvar_account_info = instruction_sysvar_account.to_account_info();
let id = "8DJXJRV8DBFjJDYyU9cTHBVK1F1CTCi6JUBDVfyBxqsT";
let instruction_sysvar = instruction_sysvar_account_info.data.borrow();
let mut idx = 0;
let num_instructions = read_u16(&mut idx, &instruction_sysvar)
.map_err(|_| MyError::NoInstructionFound)?;
for index in 0..num_instructions {
let mut current = 2 + (index * 2) as usize;
let start = read_u16(&mut current, &instruction_sysvar).unwrap();
current = start as usize;
let num_accounts = read_u16(&mut current, &instruction_sysvar).unwrap();
current += (num_accounts as usize) * (1 + 32);
let program_id = read_pubkey(&mut current, &instruction_sysvar).unwrap();
if program_id != id
{
msg!("Transaction had ix with program id {}", program_id);
return Err(MyError::SuspiciousTransaction.into());
}
}
Ok(())
}
}
#[derive(Accounts)]
#[instruction(creator_bump:u8)]
pub struct ReadMultipleInstruction<'info> {
#[account(address = sysvar::instructions::id())]
instruction_sysvar_account: UncheckedAccount<'info>
}
#[error_code]
pub enum MyError {
#[msg("No instructions found")]
NoInstructionFound,
#[msg("Suspicious transaction detected")]
SuspiciousTransaction
}