CPI to SPL Token

Token operations go through the SPL Token program via spl_token::instruction builders. Validate mints, authorities, and decimals before any CPI.

Recipe

let ix = spl_token::instruction::transfer(
  token_program.key, source.key, dest.key, authority.key, &[], amount,
)?;
invoke(&ix, accounts)?;

When to reach for this:

• Escrow release transfers.
• Minting reward tokens.
• Burning fee tokens.

Working Example

pub fn cpi_transfer(amount: u64, token_program: &AccountInfo, source: &AccountInfo, dest: &AccountInfo, auth: &AccountInfo, bump: u8) -> ProgramResult {
    let ix = spl_token::instruction::transfer(token_program.key, source.key, dest.key, auth.key, &[], amount)?;
    invoke_signed(&ix, &[source.clone(), dest.clone(), auth.clone(), token_program.clone()], &[&[b"auth", &[bump]]])
}

What this demonstrates:

• spl_token helper builds data + metas.
• PDA authority uses invoke_signed.
• Amount is raw token units (decimals).

Deep Dive

Checks

• Source/dest mint match
• Authority owns source
• Token program id correct (Token vs Token-2022)

Token-2022

Separate program id - pass correct program account.

Rust Notes

use spl_token::state::Account as TokenAccount;

Gotchas

• Wrong token program id - Token-2022 vs classic.. Fix: Validate program account key.
• Mint mismatch - Drain wrong pool.. Fix: Unpack and compare mint pubkeys.
• Decimals confusion - Off-by 10^n.. Fix: Use raw amounts consistently.
• Missing delegate check - Unauthorized transfer.. Fix: Validate authority field.
• Freeze account - Transfer fails.. Fix: Handle error code.

Alternatives

FAQs

Related

• SPL Token in Programs - Overview
• PDAs as Authorities - PDA mint
• Vault & Escrow - Escrow

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, anchor-lang 0.32.1, Rust 1.91.1, @solana/kit 7.0.0, Surfpool 0.12.0, and LiteSVM 0.6.x.