Prevents EthereumBlobExporter from consuming dest when returning NotApplicable

bridges/snowbridge/primitives/router/src/outbound/mod.rs

@@ -71,9 +71,13 @@ impl<UniversalLocation, EthereumNetwork, OutboundQueue, AgentHashedDescription,
 		let dest = destination.take().ok_or(SendError::MissingArgument)?;
 		if dest != Here {
 			log::trace!(target: "xcm::ethereum_blob_exporter", "skipped due to unmatched remote destination {dest:?}.");
+			// We need to make sure that mutable variables are not consumed in case of
+			// `NotApplicable`, since they may be used by a subsequent exporter.
+			*destination = Some(dest);
 			return Err(SendError::NotApplicable)
 		}
 
+		let universal_source_value = universal_source.clone();
 		let (local_net, local_sub) = universal_source
 			.take()
 			.ok_or_else(|| {
@@ -88,6 +92,10 @@ impl<UniversalLocation, EthereumNetwork, OutboundQueue, AgentHashedDescription,
 
 		if Ok(local_net) != universal_location.global_consensus() {
 			log::trace!(target: "xcm::ethereum_blob_exporter", "skipped due to unmatched relay network {local_net:?}.");
+			// We need to make sure that mutable variables are not consumed in case of
+			// `NotApplicable`, since they may be used by a subsequent exporter.
+			*universal_source = universal_source_value.clone();
+			*destination = Some(dest);
 			return Err(SendError::NotApplicable)
 		}
 

bridges/snowbridge/primitives/router/src/outbound/tests.rs

@@ -1163,3 +1163,107 @@ fn xcm_converter_transfer_native_token_with_invalid_location_will_fail() {
 	let result = converter.convert();
 	assert_eq!(result.err(), Some(XcmConverterError::InvalidAsset));
 }
+
+#[test]
+fn exporter_validate_with_invalid_dest_does_not_alter_destination() {
+	let network = BridgedNetwork::get();
+	let destination: InteriorLocation = Parachain(1000).into();
+
+	let universal_source: InteriorLocation = [GlobalConsensus(Polkadot), Parachain(1000)].into();
+
+	let token_address: [u8; 20] = hex!("1000000000000000000000000000000000000000");
+	let beneficiary_address: [u8; 20] = hex!("2000000000000000000000000000000000000000");
+
+	let channel: u32 = 0;
+	let assets: Assets = vec![Asset {
+		id: AssetId([AccountKey20 { network: None, key: token_address }].into()),
+		fun: Fungible(1000),
+	}]
+	.into();
+	let fee = assets.clone().get(0).unwrap().clone();
+	let filter: AssetFilter = assets.clone().into();
+	let msg: Xcm<()> = vec![
+		WithdrawAsset(assets.clone()),
+		ClearOrigin,
+		BuyExecution { fees: fee, weight_limit: Unlimited },
+		DepositAsset {
+			assets: filter,
+			beneficiary: AccountKey20 { network: None, key: beneficiary_address }.into(),
+		},
+		SetTopic([0; 32]),
+	]
+	.into();
+	let mut msg_wrapper: Option<Xcm<()>> = Some(msg.clone());
+	let mut dest_wrapper = Some(destination.clone());
+	let mut universal_source_wrapper = Some(universal_source.clone());
+
+	let result =
+		EthereumBlobExporter::<
+			UniversalLocation,
+			BridgedNetwork,
+			MockOkOutboundQueue,
+			AgentIdOf,
+			MockTokenIdConvert,
+		>::validate(
+			network, channel, &mut universal_source_wrapper, &mut dest_wrapper, &mut msg_wrapper
+		);
+
+	assert_eq!(result, Err(XcmSendError::NotApplicable));
+
+	// ensure mutable variables are not changed
+	assert_eq!(Some(destination), dest_wrapper);
+	assert_eq!(Some(msg), msg_wrapper);
+	assert_eq!(Some(universal_source), universal_source_wrapper);
+}
+
+#[test]
+fn exporter_validate_with_invalid_universal_source_does_not_alter_universal_source() {
+	let network = BridgedNetwork::get();
+	let destination: InteriorLocation = Here.into();
+
+	let universal_source: InteriorLocation = [GlobalConsensus(Westend), Parachain(1000)].into();
+
+	let token_address: [u8; 20] = hex!("1000000000000000000000000000000000000000");
+	let beneficiary_address: [u8; 20] = hex!("2000000000000000000000000000000000000000");
+
+	let channel: u32 = 0;
+	let assets: Assets = vec![Asset {
+		id: AssetId([AccountKey20 { network: None, key: token_address }].into()),
+		fun: Fungible(1000),
+	}]
+	.into();
+	let fee = assets.clone().get(0).unwrap().clone();
+	let filter: AssetFilter = assets.clone().into();
+	let msg: Xcm<()> = vec![
+		WithdrawAsset(assets.clone()),
+		ClearOrigin,
+		BuyExecution { fees: fee, weight_limit: Unlimited },
+		DepositAsset {
+			assets: filter,
+			beneficiary: AccountKey20 { network: None, key: beneficiary_address }.into(),
+		},
+		SetTopic([0; 32]),
+	]
+	.into();
+	let mut msg_wrapper: Option<Xcm<()>> = Some(msg.clone());
+	let mut dest_wrapper = Some(destination.clone());
+	let mut universal_source_wrapper = Some(universal_source.clone());
+
+	let result =
+		EthereumBlobExporter::<
+			UniversalLocation,
+			BridgedNetwork,
+			MockOkOutboundQueue,
+			AgentIdOf,
+			MockTokenIdConvert,
+		>::validate(
+			network, channel, &mut universal_source_wrapper, &mut dest_wrapper, &mut msg_wrapper
+		);
+
+	assert_eq!(result, Err(XcmSendError::NotApplicable));
+
+	// ensure mutable variables are not changed
+	assert_eq!(Some(destination), dest_wrapper);
+	assert_eq!(Some(msg), msg_wrapper);
+	assert_eq!(Some(universal_source), universal_source_wrapper);
+}