From 677b9b681f5e2819fe34599beb0947adc22afabd Mon Sep 17 00:00:00 2001
From: Luke Parker <lukeparker5132@gmail.com>
Date: Mon, 10 Jul 2023 14:43:46 -0400
Subject: [PATCH] 3.9/3.10. 3.9: Remove cast which fails on a several GB
 malicious TX

3.10 has its impossibility documented. A malicious RPC cananot effect this code.
---
 coins/bitcoin/src/wallet/mod.rs  | 7 ++++++-
 coins/bitcoin/src/wallet/send.rs | 2 ++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/coins/bitcoin/src/wallet/mod.rs b/coins/bitcoin/src/wallet/mod.rs
index 46ffff96..3997730e 100644
--- a/coins/bitcoin/src/wallet/mod.rs
+++ b/coins/bitcoin/src/wallet/mod.rs
@@ -137,11 +137,16 @@ impl Scanner {
   pub fn scan_transaction(&self, tx: &Transaction) -> Vec<ReceivedOutput> {
     let mut res = vec![];
     for (vout, output) in tx.output.iter().enumerate() {
+      // If the vout index exceeds 2**32, stop scanning outputs
+      let Ok(vout) = u32::try_from(vout) else {
+        break
+      };
+
       if let Some(offset) = self.scripts.get(&output.script_pubkey) {
         res.push(ReceivedOutput {
           offset: *offset,
           output: output.clone(),
-          outpoint: OutPoint::new(tx.txid(), u32::try_from(vout).unwrap()),
+          outpoint: OutPoint::new(tx.txid(), vout),
         });
       }
     }
diff --git a/coins/bitcoin/src/wallet/send.rs b/coins/bitcoin/src/wallet/send.rs
index a176c2fc..7e245407 100644
--- a/coins/bitcoin/src/wallet/send.rs
+++ b/coins/bitcoin/src/wallet/send.rs
@@ -221,6 +221,8 @@ impl SignableTransaction {
     let mut sigs = vec![];
     for i in 0 .. tx.input.len() {
       let mut transcript = transcript.clone();
+      // This unwrap is safe since any transaction with this many inputs violates the maximum
+      // size allowed under standards, which this lib will error on creation of
       transcript.append_message(b"signing_input", u32::try_from(i).unwrap().to_le_bytes());
 
       let offset = keys.clone().offset(self.offsets[i]);