Enforce transparent sus fee receivers

Author: sug0

crates/sdk/src/args.rs

@@ -9,7 +9,7 @@ use std::time::Duration as StdDuration;
 use either::Either;
 use masp_primitives::transaction::components::sapling::builder::BuildParams;
 use masp_primitives::zip32::PseudoExtendedKey;
-use namada_core::address::Address;
+use namada_core::address::{Address, MASP};
 use namada_core::chain::{BlockHeight, ChainId, Epoch};
 use namada_core::collections::HashMap;
 use namada_core::dec::Dec;
@@ -677,7 +677,18 @@ impl TxOsmosisSwap<SdkTypes> {
                 break 'frontend_sus_fee None;
             }
 
-            let fee_receiver = target.effective_address();
+            let fee_receiver = match target {
+                crate::TransferTarget::Address(MASP)
+                | crate::TransferTarget::PaymentAddress(_)
+                | crate::TransferTarget::Ibc(_) => {
+                    return Err(Error::Other(
+                        "Only transparent sus fee receivers are supported in \
+                         Osmosis shielded swaps"
+                            .to_owned(),
+                    ));
+                }
+                crate::TransferTarget::Address(addr) => addr.clone(),
+            };
             let fee_amount = tx::compute_raw_masp_frontend_sus_fee(
                 &trade_min_output_amount,
                 percentage,