Correctly fail back blinded HTLCs on onion decode and Channel error

TODO: finish tests

Author: valentinewallace

lightning/src/ln/channelmanager.rs

@@ -3001,10 +3001,18 @@ where
 		{
 			Ok(res) => res,
 			Err(onion_utils::OnionDecodeErr::Malformed { err_msg, err_code }) => {
-				return_malformed_err!(err_msg, err_code);
+				if msg.blinding_point.is_some() {
+					return_blinded_htlc_err!(err_msg);
+				} else {
+					return_malformed_err!(err_msg, err_code);
+				}
 			},
 			Err(onion_utils::OnionDecodeErr::Relay { err_msg, err_code }) => {
-				return_err!(err_msg, err_code, &[0; 0]);
+				if msg.blinding_point.is_some() {
+					return_blinded_htlc_err!(err_msg);
+				} else {
+					return_err!(err_msg, err_code, &[0; 0]);
+				}
 			},
 		};
 		let (outgoing_scid, outgoing_amt_msat, outgoing_cltv_value, next_packet_pk_opt, blinded)
@@ -3205,10 +3213,18 @@ where
 			($msg: expr, $err_code: expr, $data: expr) => {
 				{
 					log_info!(self.logger, "Failed to accept/forward incoming HTLC: {}", $msg);
+					let (err_code, err_data) = if msg.blinding_point.is_some() {
+						return PendingHTLCStatus::Fail(HTLCFailureMsg::Malformed(msgs::UpdateFailMalformedHTLC {
+							channel_id: msg.channel_id,
+							htlc_id: msg.htlc_id,
+							sha256_of_onion: [0; 32],
+							failure_code: INVALID_ONION_BLINDING,
+						}))
+					} else { ($err_code, $data) };
 					return PendingHTLCStatus::Fail(HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
 						channel_id: msg.channel_id,
 						htlc_id: msg.htlc_id,
-						reason: HTLCFailReason::reason($err_code, $data.to_vec())
+						reason: HTLCFailReason::reason(err_code, err_data.to_vec())
 							.get_encrypted_failure_packet(&shared_secret, &None),
 					}));
 				}
@@ -6104,8 +6120,21 @@ where
 					// but if we've sent a shutdown and they haven't acknowledged it yet, we just
 					// want to reject the new HTLC and fail it backwards instead of forwarding.
 					match pending_forward_info {
-						PendingHTLCStatus::Forward(PendingHTLCInfo { ref incoming_shared_secret, .. }) => {
-							let reason = if (error_code & 0x1000) != 0 {
+						PendingHTLCStatus::Forward(PendingHTLCInfo {
+							ref incoming_shared_secret, ref routing, ..
+						}) => {
+							if msg.blinding_point.is_some() {
+								let fail_malformed = msgs::UpdateFailMalformedHTLC {
+									channel_id: msg.channel_id,
+									htlc_id: msg.htlc_id,
+									sha256_of_onion: [0; 32],
+									failure_code: INVALID_ONION_BLINDING,
+								};
+								return PendingHTLCStatus::Fail(HTLCFailureMsg::Malformed(fail_malformed))
+							}
+							let reason = if routing.blinded().is_some() {
+								HTLCFailReason::reason(INVALID_ONION_BLINDING, vec![0; 32])
+							} else if (error_code & 0x1000) != 0 {
 								let (real_code, error_data) = self.get_htlc_inbound_temp_fail_err_and_data(error_code, chan);
 								HTLCFailReason::reason(real_code, error_data)
 							} else {