fix(wallet)!: enforce OP_RETURN standardness

Author: rustaceanrob

crates/wallet/src/wallet/error.rs

@@ -104,6 +104,10 @@ pub enum CreateTxError {
     MissingNonWitnessUtxo(OutPoint),
     /// Miniscript PSBT error
     MiniscriptPsbt(MiniscriptPsbtError),
+    /// Multiple recipients are OP_RETURN outputs
+    MultipleOpReturn,
+    /// The OP_RETURN data contains too many bytes
+    MaxDataCarrierSize,
 }
 
 impl fmt::Display for CreateTxError {
@@ -171,6 +175,12 @@ impl fmt::Display for CreateTxError {
             CreateTxError::MiniscriptPsbt(err) => {
                 write!(f, "Miniscript PSBT error: {}", err)
             }
+            CreateTxError::MultipleOpReturn => {
+                write!(f, "Multiple recipients are OP_RETURN outputs")
+            }
+            CreateTxError::MaxDataCarrierSize => {
+                write!(f, "The OP_RETURN data contains too many bytes")
+            }
         }
     }
 }

crates/wallet/src/wallet/mod.rs

@@ -87,6 +87,7 @@ pub use persisted::*;
 pub use utils::IsDust;
 
 const COINBASE_MATURITY: u32 = 100;
+const MAX_OP_RETURN_BYTES: usize = 83;
 
 /// A Bitcoin wallet
 ///
@@ -1388,12 +1389,23 @@ impl Wallet {
         let mut received = Amount::ZERO;
 
         let recipients = params.recipients.iter().map(|(r, v)| (r, *v));
+        let mut contains_op_return = false;
 
         for (index, (script_pubkey, value)) in recipients.enumerate() {
             if !params.allow_dust && value.is_dust(script_pubkey) && !script_pubkey.is_op_return() {
                 return Err(CreateTxError::OutputBelowDustLimit(index));
             }
 
+            if script_pubkey.is_op_return() {
+                if contains_op_return {
+                    return Err(CreateTxError::MultipleOpReturn);
+                }
+                if script_pubkey.len() > MAX_OP_RETURN_BYTES {
+                    return Err(CreateTxError::MaxDataCarrierSize);
+                }
+                contains_op_return = true;
+            }
+
             if self.is_mine(script_pubkey.clone()) {
                 received += value;
             }