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Version: Canary 🚧

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
}