solana: Refactor token_authority_sig, simplify release_inbox_item logic, move constraint back to struct

Author: nvsriram

solana/programs/example-native-token-transfers/src/instructions/release_inbound.rs

@@ -62,6 +62,7 @@ pub struct ReleaseInboundArgs {
 pub struct ReleaseInboundMint<'info> {
     #[account(
         constraint = common.config.mode == Mode::Burning @ NTTError::InvalidMode,
+        constraint = common.mint.mint_authority.unwrap() == common.token_authority.key()
     )]
     common: ReleaseInbound<'info>,
 }
@@ -77,11 +78,6 @@ pub fn release_inbound_mint<'info>(
     ctx: Context<'_, '_, '_, 'info, ReleaseInboundMint<'info>>,
     args: ReleaseInboundArgs,
 ) -> Result<()> {
-    if ctx.accounts.common.mint.mint_authority.unwrap() != ctx.accounts.common.token_authority.key()
-    {
-        return Err(NTTError::InvalidMintAuthority.into());
-    }
-
     let inbox_item = release_inbox_item(&mut ctx.accounts.common.inbox_item, args.revert_on_delay)?;
 
     // NOTE: minting tokens is a two-step process:
@@ -99,6 +95,11 @@ pub fn release_inbound_mint<'info>(
     // The [`transfer_burn`] function operates in a similar way
     // (transfer to custody from sender, *then* burn).
 
+    let token_authority_sig: &[&[&[u8]]] = &[&[
+        crate::TOKEN_AUTHORITY_SEED,
+        &[ctx.bumps.common.token_authority],
+    ]];
+
     // Step 1: mint tokens to the custody account
     token_interface::mint_to(
         CpiContext::new_with_signer(
@@ -108,10 +109,7 @@ pub fn release_inbound_mint<'info>(
                 to: ctx.accounts.common.custody.to_account_info(),
                 authority: ctx.accounts.common.token_authority.to_account_info(),
             },
-            &[&[
-                crate::TOKEN_AUTHORITY_SEED,
-                &[ctx.bumps.common.token_authority],
-            ]],
+            token_authority_sig,
         ),
         inbox_item.amount,
     )?;
@@ -126,10 +124,7 @@ pub fn release_inbound_mint<'info>(
         ctx.remaining_accounts,
         inbox_item.amount,
         ctx.accounts.common.mint.decimals,
-        &[&[
-            crate::TOKEN_AUTHORITY_SEED,
-            &[ctx.bumps.common.token_authority],
-        ]],
+        token_authority_sig,
     )?;
     Ok(())
 }
@@ -167,27 +162,28 @@ pub fn release_inbound_mint_multisig<'info>(
     // The [`transfer_burn`] function operates in a similar way
     // (transfer to custody from sender, *then* burn).
 
+    let token_authority_sig: &[&[&[u8]]] = &[&[
+        crate::TOKEN_AUTHORITY_SEED,
+        &[ctx.bumps.common.token_authority],
+    ]];
+
     // Step 1: mint tokens to the custody account
-    let ix = spl_token_2022::instruction::mint_to(
-        &ctx.accounts.common.token_program.key(),
-        &ctx.accounts.common.mint.key(),
-        &ctx.accounts.common.custody.key(),
-        &ctx.accounts.multisig.key(),
-        &[&ctx.accounts.common.token_authority.key()],
-        inbox_item.amount,
-    )?;
     solana_program::program::invoke_signed(
-        &ix,
+        &spl_token_2022::instruction::mint_to(
+            &ctx.accounts.common.token_program.key(),
+            &ctx.accounts.common.mint.key(),
+            &ctx.accounts.common.custody.key(),
+            &ctx.accounts.multisig.key(),
+            &[&ctx.accounts.common.token_authority.key()],
+            inbox_item.amount,
+        )?,
         &[
             ctx.accounts.common.custody.to_account_info(),
             ctx.accounts.common.mint.to_account_info(),
             ctx.accounts.common.token_authority.to_account_info(),
             ctx.accounts.multisig.to_account_info(),
         ],
-        &[&[
-            crate::TOKEN_AUTHORITY_SEED,
-            &[ctx.bumps.common.token_authority],
-        ]],
+        token_authority_sig,
     )?;
 
     // Step 2: transfer the tokens from the custody account to the recipient
@@ -200,10 +196,7 @@ pub fn release_inbound_mint_multisig<'info>(
         ctx.remaining_accounts,
         inbox_item.amount,
         ctx.accounts.common.mint.decimals,
-        &[&[
-            crate::TOKEN_AUTHORITY_SEED,
-            &[ctx.bumps.common.token_authority],
-        ]],
+        token_authority_sig,
     )?;
     Ok(())
 }
@@ -250,17 +243,12 @@ pub fn release_inbound_unlock<'info>(
 }
 
 fn release_inbox_item(inbox_item: &mut InboxItem, revert_on_delay: bool) -> Result<&mut InboxItem> {
-    let released = inbox_item.try_release()?;
-
-    if !released {
-        if revert_on_delay {
-            return Err(NTTError::CantReleaseYet.into());
-        } else {
-            return Ok(inbox_item);
-        }
+    if inbox_item.try_release()? {
+        assert!(inbox_item.release_status == ReleaseStatus::Released);
+        Ok(inbox_item)
+    } else if revert_on_delay {
+        Err(NTTError::CantReleaseYet.into())
+    } else {
+        Ok(inbox_item)
     }
-
-    assert!(inbox_item.release_status == ReleaseStatus::Released);
-
-    Ok(inbox_item)
 }