From 8287561c45d1447563830375c3fb327f2653573f Mon Sep 17 00:00:00 2001
From: hanako mumei <81144685+2501babe@users.noreply.github.com>
Date: Tue, 22 Oct 2024 12:43:25 -0700
Subject: [PATCH] CODE: split nonce validation into its own function

---
 svm/src/transaction_processor.rs | 78 +++++++++++++++++++-------------
 1 file changed, 47 insertions(+), 31 deletions(-)

diff --git a/svm/src/transaction_processor.rs b/svm/src/transaction_processor.rs
index 0710b0d97c7b5a..66612c32563a25 100644
--- a/svm/src/transaction_processor.rs
+++ b/svm/src/transaction_processor.rs
@@ -9,6 +9,7 @@ use {
         },
         account_overrides::AccountOverrides,
         message_processor::MessageProcessor,
+        nonce_info::NonceInfo,
         program_loader::{get_program_modification_slot, load_program_with_pubkey},
         rollback_accounts::RollbackAccounts,
         transaction_account_state_info::TransactionAccountStateInfo,
@@ -494,38 +495,13 @@ impl<FG: ForkGraph> TransactionBatchProcessor<FG> {
             fee_details.total_fee(),
         )?;
 
-        // If the nonce has been used in this batch already, we must drop the transaction
-        // This is the same as if it was used in different batches in the same slot
-        // If the nonce account was closed in the batch, we error as if the blockhash didn't validate
-        // We must validate the account in case it was reopened, either as a normal system account, or a fake nonce account
         if let Some(ref advanced_nonce_info) = advanced_nonce {
-            let nonces_are_equal = account_loader
-                .load_account(advanced_nonce_info.address(), AccountUsagePattern::Writable)
-                .and_then(|loaded_nonce| {
-                    let current_nonce_account = &loaded_nonce.account;
-                    system_program::check_id(current_nonce_account.owner()).then_some(())?;
-                    StateMut::<NonceVersions>::state(current_nonce_account).ok()
-                })
-                .and_then(
-                    |current_nonce_versions| match current_nonce_versions.state() {
-                        NonceState::Initialized(ref current_nonce_data) => {
-                            Some(&current_nonce_data.durable_nonce == durable_nonce)
-                        }
-                        _ => None,
-                    },
-                );
-
-            match nonces_are_equal {
-                Some(false) => (),
-                Some(true) => {
-                    error_counters.account_not_found += 1;
-                    return Err(TransactionError::AccountNotFound);
-                }
-                None => {
-                    error_counters.blockhash_not_found += 1;
-                    return Err(TransactionError::BlockhashNotFound);
-                }
-            }
+            self.validate_transaction_nonce(
+                account_loader,
+                advanced_nonce_info,
+                durable_nonce,
+                error_counters,
+            )?;
         }
 
         // Capture fee-subtracted fee payer account and next nonce account state
@@ -546,6 +522,46 @@ impl<FG: ForkGraph> TransactionBatchProcessor<FG> {
         })
     }
 
+    fn validate_transaction_nonce<CB: TransactionProcessingCallback>(
+        &self,
+        account_loader: &mut AccountLoader<CB>,
+        advanced_nonce_info: &NonceInfo,
+        durable_nonce: &DurableNonce,
+        error_counters: &mut TransactionErrorMetrics,
+    ) -> transaction::Result<()> {
+        // If the nonce has been used in this batch already, we must drop the transaction
+        // This is the same as if it was used in different batches in the same slot
+        // If the nonce account was closed in the batch, we error as if the blockhash didn't validate
+        // We must validate the account in case it was reopened, either as a normal system account, or a fake nonce account
+        let nonces_are_equal = account_loader
+            .load_account(advanced_nonce_info.address(), AccountUsagePattern::Writable)
+            .and_then(|loaded_nonce| {
+                let current_nonce_account = &loaded_nonce.account;
+                system_program::check_id(current_nonce_account.owner()).then_some(())?;
+                StateMut::<NonceVersions>::state(current_nonce_account).ok()
+            })
+            .and_then(
+                |current_nonce_versions| match current_nonce_versions.state() {
+                    NonceState::Initialized(ref current_nonce_data) => {
+                        Some(&current_nonce_data.durable_nonce == durable_nonce)
+                    }
+                    _ => None,
+                },
+            );
+
+        match nonces_are_equal {
+            None => {
+                error_counters.blockhash_not_found += 1;
+                Err(TransactionError::BlockhashNotFound)
+            }
+            Some(true) => {
+                error_counters.account_not_found += 1;
+                Err(TransactionError::AccountNotFound)
+            }
+            Some(false) => Ok(()),
+        }
+    }
+
     /// Returns a map from executable program accounts (all accounts owned by any loader)
     /// to their usage counters, for the transactions with a valid blockhash or nonce.
     fn filter_executable_program_accounts<CB: TransactionProcessingCallback>(