Fixes https://github.com/bisq-network/bisq/issues/2804 and https://github.com/bisq-network/bisq/issues/2826

core/src/main/java/bisq/core/btc/exceptions/BsqChangeBelowDustException.java

@@ -0,0 +1,33 @@
+/*
+ * This file is part of Bisq.
+ *
+ * Bisq is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * Bisq is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Bisq. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package bisq.core.btc.exceptions;
+
+import org.bitcoinj.core.Coin;
+
+import lombok.Getter;
+
+public class BsqChangeBelowDustException extends Exception {
+    @Getter
+    private final Coin outputValue;
+
+    public BsqChangeBelowDustException(String message, Coin outputValue) {
+        super(message);
+
+        this.outputValue = outputValue;
+    }
+}

core/src/main/java/bisq/core/btc/wallet/BsqWalletService.java

@@ -17,6 +17,7 @@
 
 package bisq.core.btc.wallet;
 
+import bisq.core.btc.exceptions.BsqChangeBelowDustException;
 import bisq.core.btc.exceptions.InsufficientBsqException;
 import bisq.core.btc.exceptions.TransactionVerificationException;
 import bisq.core.btc.exceptions.WalletException;
@@ -475,7 +476,7 @@ public class BsqWalletService extends WalletService implements DaoStateListener
     ///////////////////////////////////////////////////////////////////////////////////////////
 
     public Transaction getPreparedSendBsqTx(String receiverAddress, Coin receiverAmount)
-            throws AddressFormatException, InsufficientBsqException, WalletException, TransactionVerificationException {
+            throws AddressFormatException, InsufficientBsqException, WalletException, TransactionVerificationException, BsqChangeBelowDustException {
         return getPreparedSendTx(receiverAddress, receiverAmount, bsqCoinSelector);
     }
 
@@ -484,12 +485,12 @@ public class BsqWalletService extends WalletService implements DaoStateListener
     ///////////////////////////////////////////////////////////////////////////////////////////
 
     public Transaction getPreparedSendBtcTx(String receiverAddress, Coin receiverAmount)
-            throws AddressFormatException, InsufficientBsqException, WalletException, TransactionVerificationException {
+            throws AddressFormatException, InsufficientBsqException, WalletException, TransactionVerificationException, BsqChangeBelowDustException {
         return getPreparedSendTx(receiverAddress, receiverAmount, nonBsqCoinSelector);
     }
 
     private Transaction getPreparedSendTx(String receiverAddress, Coin receiverAmount, CoinSelector coinSelector)
-            throws AddressFormatException, InsufficientBsqException, WalletException, TransactionVerificationException {
+            throws AddressFormatException, InsufficientBsqException, WalletException, TransactionVerificationException, BsqChangeBelowDustException {
         DaoKillSwitch.assertDaoIsNotDisabled();
         Transaction tx = new Transaction(params);
         checkArgument(Restrictions.isAboveDust(receiverAmount),
@@ -510,6 +511,18 @@ public class BsqWalletService extends WalletService implements DaoStateListener
             checkWalletConsistency(wallet);
             verifyTransaction(tx);
             // printTx("prepareSendTx", tx);
+
+            // Tx has as first output BSQ and an optional second BSQ change output.
+            // At that stage we do not have added the BTC inputs so there is no BTC change output here.
+            if (tx.getOutputs().size() == 2) {
+                TransactionOutput bsqChangeOutput = tx.getOutputs().get(1);
+                if (!Restrictions.isAboveDust(bsqChangeOutput.getValue())) {
+                    String msg = "BSQ change output is below dust limit. outputValue=" + bsqChangeOutput.getValue().toFriendlyString();
+                    log.warn(msg);
+                    throw new BsqChangeBelowDustException(msg, bsqChangeOutput.getValue());
+                }
+            }
+
             return tx;
         } catch (InsufficientMoneyException e) {
             log.error(e.toString());

core/src/main/resources/i18n/displayStrings.properties

@@ -2278,6 +2278,15 @@ popup.warning.noPriceFeedAvailable=There is no price feed available for that cur
 popup.warning.sendMsgFailed=Sending message to your trading partner failed.\nPlease try again and if it continue to fail report a bug.
 popup.warning.insufficientBtcFundsForBsqTx=You don''t have sufficient BTC funds for paying the miner fee for that transaction.\n\
 Please fund your BTC wallet.\nMissing funds: {0}
+popup.warning.bsqChangeBelowDustException=This transaction creates a BSQ change output which is below dust \
+  limit (5.46 BSQ) and would be rejected by the bitcoin network.\n\n\
+  You need to either send a higher amount to avoid the change output (e.g. by adding the dust amount to your \
+  sending amount) or add more BSQ funds to your wallet so you avoid to generate a dust output.\n\n\
+  The dust output is {0}.
+popup.warning.btcChangeBelowDustException=This transaction creates a change output which is below dust \
+  limit (546 Satoshi) and would be rejected by the bitcoin network.\n\n\
+  You need to add the dust amount to your sending amount to avoid to generate a dust output.\n\n\
+  The dust output is {0}.
 
 popup.warning.insufficientBsqFundsForBtcFeePayment=You don''t have sufficient BSQ funds for paying the trade fee in BSQ. \
 You can pay the fee in BTC or you need to fund your BSQ wallet. You can buy BSQ in Bisq.\n\n\

desktop/src/main/java/bisq/desktop/main/dao/wallet/send/BsqSendView.java

@@ -33,6 +33,7 @@ import bisq.desktop.util.validation.BsqAddressValidator;
 import bisq.desktop.util.validation.BsqValidator;
 import bisq.desktop.util.validation.BtcValidator;
 
+import bisq.core.btc.exceptions.BsqChangeBelowDustException;
 import bisq.core.btc.exceptions.TxBroadcastException;
 import bisq.core.btc.listeners.BsqBalanceListener;
 import bisq.core.btc.setup.WalletsSetup;
@@ -85,7 +86,7 @@ public class BsqSendView extends ActivatableView<GridPane, Void> implements BsqB
 
     private int gridRow = 0;
     private InputTextField amountInputTextField, btcAmountInputTextField;
-    private Button sendButton, sendBtcButton;
+    private Button sendBsqButton, sendBtcButton;
     private InputTextField receiversAddressInputTextField, receiversBtcAddressInputTextField;
     private ChangeListener<Boolean> focusOutListener;
     private TitledGroupBg btcTitledGroupBg;
@@ -200,7 +201,7 @@ public class BsqSendView extends ActivatableView<GridPane, Void> implements BsqB
         bsqValidator.setAvailableBalance(availableConfirmedBalance);
         boolean isValid = bsqAddressValidator.validate(receiversAddressInputTextField.getText()).isValid &&
                 bsqValidator.validate(amountInputTextField.getText()).isValid;
-        sendButton.setDisable(!isValid);
+        sendBsqButton.setDisable(!isValid);
 
         boolean isBtcValid = btcAddressValidator.validate(receiversBtcAddressInputTextField.getText()).isValid &&
                 btcValidator.validate(btcAmountInputTextField.getText()).isValid;
@@ -227,9 +228,9 @@ public class BsqSendView extends ActivatableView<GridPane, Void> implements BsqB
                 onUpdateBalances();
         };
 
-        sendButton = addButtonAfterGroup(root, ++gridRow, Res.get("dao.wallet.send.send"));
+        sendBsqButton = addButtonAfterGroup(root, ++gridRow, Res.get("dao.wallet.send.send"));
 
-        sendButton.setOnAction((event) -> {
+        sendBsqButton.setOnAction((event) -> {
             // TODO break up in methods
             if (GUIUtil.isReadyForTxBroadcast(p2PService, walletsSetup)) {
                 String receiversAddressString = bsqFormatter.getAddressFromBsqAddress(receiversAddressInputTextField.getText()).toString();
@@ -252,6 +253,9 @@ public class BsqSendView extends ActivatableView<GridPane, Void> implements BsqB
                                 receiversAddressInputTextField.setText("");
                                 amountInputTextField.setText("");
                             });
+                } catch (BsqChangeBelowDustException e) {
+                    String msg = Res.get("popup.warning.bsqChangeBelowDustException", bsqFormatter.formatCoinWithCode(e.getOutputValue()));
+                    new Popup<>().warning(msg).show();
                 } catch (Throwable t) {
                     handleError(t);
                 }
@@ -314,7 +318,9 @@ public class BsqSendView extends ActivatableView<GridPane, Void> implements BsqB
                                 });
 
                     }
-
+                } catch (BsqChangeBelowDustException e) {
+                    String msg = Res.get("popup.warning.btcChangeBelowDustException", btcFormatter.formatCoinWithCode(e.getOutputValue()));
+                    new Popup<>().warning(msg).show();
                 } catch (Throwable t) {
                     handleError(t);
                 }