solana: add dummy transfer hook

Author: kcsongor

solana/Anchor.toml

@@ -7,9 +7,10 @@ seeds = false
 skip-lint = false
 
 [programs.localnet]
+dummy-transfer-hook = "BgabMDLaxsyB7eGMBt9L22MSk9KMrL4zY2iNe14kyFP5"
 example_native_token_transfers = "nttiK1SepaQt6sZ4WGW5whvc9tEnGXGxuKeptcQPCcS"
-wormhole_governance = "wgvEiKVzX9yyEoh41jZAdC6JqGUTS4CFXbFGBV5TKdZ"
 ntt_quoter = "9jFBLvMZZERVmeY4tbq5MejbXRE18paGEuoB6xVJZgGe"
+wormhole_governance = "wgvEiKVzX9yyEoh41jZAdC6JqGUTS4CFXbFGBV5TKdZ"
 
 [registry]
 url = "https://api.apr.dev"
@@ -31,7 +32,10 @@ address = "worm2ZoG2kUd4vFXhvjh93UUH596ayRfgQ2MgjNMTth"
 program = "programs/example-native-token-transfers/tests/fixtures/mainnet_core_bridge.so"
 
 [test.validator]
+bind_address = "0.0.0.0"
 url = "https://api.mainnet-beta.solana.com"
+ledger = ".anchor/test-ledger"
+rpc_port = 8899
 ticks_per_slot = 16
 
 [[test.validator.account]]

solana/Cargo.lock

@@ -0,0 +1,23 @@
+[package]
+name = "dummy-transfer-hook"
+version = "0.1.0"
+description = "Created with Anchor"
+edition = "2021"
+
+[lib]
+crate-type = ["cdylib", "lib"]
+name = "dummy_transfer_hook"
+
+[features]
+no-entrypoint = []
+no-idl = []
+no-log-ix-name = []
+cpi = ["no-entrypoint"]
+default = []
+
+[dependencies]
+anchor-lang.workspace = true
+anchor-spl.workspace = true
+solana-program.workspace = true
+spl-tlv-account-resolution = "0.6.3"
+spl-transfer-hook-interface = "0.6.3"

solana/programs/dummy-transfer-hook/Cargo.toml

@@ -0,0 +1,2 @@
+[target.bpfel-unknown-unknown.dependencies.std]
+features = []

solana/programs/dummy-transfer-hook/Xargo.toml

@@ -0,0 +1,139 @@
+use anchor_lang::prelude::*;
+use anchor_spl::{
+    associated_token::AssociatedToken,
+    token_interface::{Mint, TokenAccount, TokenInterface},
+};
+use spl_tlv_account_resolution::state::ExtraAccountMetaList;
+
+declare_id!("BgabMDLaxsyB7eGMBt9L22MSk9KMrL4zY2iNe14kyFP5");
+
+/// Index of the sender token account in the accounts passed to the transfer hook
+pub const SENDER_TOKEN_ACCOUNT_INDEX: u8 = 0;
+/// Index of the mint account in the accounts passed to the transfer hook
+pub const MINT_ACCOUNT_INDEX: u8 = 1;
+/// Index of the destination token account in the accounts passed to the transfer hook
+pub const DESTINATION_TOKEN_ACCOUNT_INDEX: u8 = 2;
+/// Index of the authority account in the accounts passed to the transfer hook
+pub const AUTHORITY_ACCOUNT_INDEX: u8 = 3;
+
+/// Number of extra accounts in the ExtraAccountMetaList account
+pub const EXTRA_ACCOUNTS_LEN: u8 = 1;
+
+#[program]
+pub mod dummy_transfer_hook {
+    use spl_tlv_account_resolution::{
+        account::ExtraAccountMeta, seeds::Seed, state::ExtraAccountMetaList,
+    };
+    use spl_transfer_hook_interface::instruction::{ExecuteInstruction, TransferHookInstruction};
+
+    use super::*;
+
+    pub fn initialize_extra_account_meta_list(
+        ctx: Context<InitializeExtraAccountMetaList>,
+    ) -> Result<()> {
+        let account_metas = vec![ExtraAccountMeta::new_with_seeds(
+            &[
+                Seed::Literal {
+                    bytes: "dummy_account".as_bytes().to_vec(),
+                },
+                // owner field of the sender token account
+                Seed::AccountData {
+                    account_index: SENDER_TOKEN_ACCOUNT_INDEX,
+                    data_index: 32,
+                    length: 32,
+                },
+            ],
+            false, // is_signer
+            false, // is_writable
+        )?];
+
+        assert_eq!(EXTRA_ACCOUNTS_LEN as usize, account_metas.len());
+
+        // initialize ExtraAccountMetaList account with extra accounts
+        ExtraAccountMetaList::init::<ExecuteInstruction>(
+            &mut ctx.accounts.extra_account_meta_list.try_borrow_mut_data()?,
+            &account_metas,
+        )?;
+
+        Ok(())
+    }
+
+    pub fn transfer_hook(_ctx: Context<TransferHook>, _amount: u64) -> Result<()> {
+        // NOTE: for now, the account constraints implement all the restrictions.
+        Ok(())
+    }
+
+    // NOTE: the CPI call makes that the token2022 program makes (naturally) does not
+    // follow the anchor calling convention, so we need to implement a fallback
+    // instruction to handle the custom instruction
+    pub fn fallback<'info>(
+        program_id: &Pubkey,
+        accounts: &'info [AccountInfo<'info>],
+        data: &[u8],
+    ) -> Result<()> {
+        let instruction = TransferHookInstruction::unpack(data)?;
+
+        // match instruction discriminator to transfer hook interface execute instruction
+        // token2022 program CPIs this instruction on token transfer
+        match instruction {
+            TransferHookInstruction::Execute { amount } => {
+                let amount_bytes = amount.to_le_bytes();
+
+                // invoke custom transfer hook instruction on our program
+                __private::__global::transfer_hook(program_id, accounts, &amount_bytes)
+            }
+            _ => Err(ProgramError::InvalidInstructionData.into()),
+        }
+    }
+}
+
+#[derive(Accounts)]
+pub struct InitializeExtraAccountMetaList<'info> {
+    #[account(mut)]
+    payer: Signer<'info>,
+
+    /// CHECK: ExtraAccountMetaList Account, must use these seeds
+    #[account(
+        init,
+        payer = payer,
+        space = ExtraAccountMetaList::size_of(EXTRA_ACCOUNTS_LEN as usize)?,
+        seeds = [b"extra-account-metas", mint.key().as_ref()],
+        bump
+    )]
+    pub extra_account_meta_list: AccountInfo<'info>,
+    pub mint: InterfaceAccount<'info, Mint>,
+    pub token_program: Interface<'info, TokenInterface>,
+    pub associated_token_program: Program<'info, AssociatedToken>,
+    pub system_program: Program<'info, System>,
+}
+
+#[derive(Accounts)]
+/// NOTE: this is just a dummy transfer hook to test that the accounts are
+/// passed in correctly. Do NOT use this as a starting point in a real
+/// application, as it's not secure.
+pub struct TransferHook<'info> {
+    #[account(
+        token::mint = mint,
+    )]
+    pub source_token: InterfaceAccount<'info, TokenAccount>,
+    pub mint: InterfaceAccount<'info, Mint>,
+    #[account(
+        token::mint = mint,
+    )]
+    pub destination_token: InterfaceAccount<'info, TokenAccount>,
+    /// CHECK: source token account authority, can be SystemAccount or PDA owned by another program
+    pub authority: UncheckedAccount<'info>,
+    /// CHECK: ExtraAccountMetaList Account,
+    #[account(
+        seeds = [b"extra-account-metas", mint.key().as_ref()],
+        bump
+    )]
+    pub extra_account_meta_list: UncheckedAccount<'info>,
+    #[account(
+        seeds = [b"dummy_account", source_token.owner.as_ref()],
+        bump
+    )]
+    /// CHECK: dummy account. It just tests that the off-chain code correctly
+    /// computes and the on-chain code correctly passes on the PDA.
+    pub dummy_account: AccountInfo<'info>,
+}