From 4ac0321acb76ac3dbd692cb1033adfdd9ef4e4d2 Mon Sep 17 00:00:00 2001
From: gerlofvanek <gerlof@particl.io>
Date: Mon, 8 Jun 2026 22:47:23 +0200
Subject: [PATCH] Verify initiate lock-tx amount.

---
 basicswap/basicswap.py         | 12 ++++++++++++
 basicswap/interface/bch.py     |  1 +
 basicswap/interface/btc.py     |  4 ++++
 basicswap/interface/dcr/dcr.py |  1 +
 basicswap/interface/firo.py    |  2 ++
 basicswap/interface/nav.py     |  2 ++
 6 files changed, 22 insertions(+)

diff --git a/basicswap/basicswap.py b/basicswap/basicswap.py
index 1bc38e7..88c7c7b 100644
--- a/basicswap/basicswap.py
+++ b/basicswap/basicswap.py
@@ -8454,6 +8454,18 @@ class BasicSwap(BaseApp, BSXNetwork, UIApp):
                 )
                 index = None
                 if found:
+                    if (
+                        "value" in found
+                        and found["value"] is not None
+                        and found["value"] != int(bid.amount)
+                    ):
+                        self.setBidError(
+                            bid,
+                            "Incorrect output amount in initiate txn {}: {} != {}.".format(
+                                initiate_txnid_hex, found["value"], int(bid.amount)
+                            ),
+                        )
+                        return True
                     bid.initiate_tx.conf = found["depth"]
                     if "index" in found:
                         index = found["index"]
diff --git a/basicswap/interface/bch.py b/basicswap/interface/bch.py
index b81e1b1..2c71f4a 100644
--- a/basicswap/interface/bch.py
+++ b/basicswap/interface/bch.py
@@ -322,6 +322,7 @@ class BCHInterface(BTCInterface):
             "depth": confirmations,
             "index": found_vout,
             "height": block_height,
+            "value": self.make_int(txout["value"]),
         }
 
         return rv
diff --git a/basicswap/interface/btc.py b/basicswap/interface/btc.py
index da62769..0488deb 100644
--- a/basicswap/interface/btc.py
+++ b/basicswap/interface/btc.py
@@ -3006,6 +3006,8 @@ class BTCInterface(FeeValidator, Secp256k1Interface):
         if find_index:
             tx_obj = self.rpc("decoderawtransaction", [tx["hex"]])
             rv["index"] = find_vout_for_address_from_txobj(tx_obj, dest_address)
+            if rv["index"] is not None and rv["index"] >= 0:
+                rv["value"] = self.make_int(tx_obj["vout"][rv["index"]]["value"])
 
         if return_txid:
             rv["txid"] = txid.hex()
@@ -3063,6 +3065,7 @@ class BTCInterface(FeeValidator, Secp256k1Interface):
                             for idx, txout in enumerate(tx.vout):
                                 if txout.scriptPubKey == dest_script:
                                     rv["index"] = idx
+                                    rv["value"] = txout.nValue
                                     break
                     except Exception:
                         pass
@@ -3124,6 +3127,7 @@ class BTCInterface(FeeValidator, Secp256k1Interface):
                     for idx, txout in enumerate(tx.vout):
                         if txout.scriptPubKey == dest_script:
                             rv["index"] = idx
+                            rv["value"] = txout.nValue
                             break
             except Exception as e:
                 self._log.debug(
diff --git a/basicswap/interface/dcr/dcr.py b/basicswap/interface/dcr/dcr.py
index ac677a4..5765e97 100644
--- a/basicswap/interface/dcr/dcr.py
+++ b/basicswap/interface/dcr/dcr.py
@@ -940,6 +940,7 @@ class DCRInterface(FeeValidator, Secp256k1Interface):
             "depth": confirmations,
             "index": found_vout,
             "height": block_height,
+            "value": self.make_int(txout["value"]),
         }
 
         return rv
diff --git a/basicswap/interface/firo.py b/basicswap/interface/firo.py
index d799ab0..24b1d20 100644
--- a/basicswap/interface/firo.py
+++ b/basicswap/interface/firo.py
@@ -276,6 +276,8 @@ class FIROInterface(BTCInterface):
         if find_index:
             tx_obj = self.rpc("decoderawtransaction", [tx["hex"]])
             rv["index"] = find_vout_for_address_from_txobj(tx_obj, dest_address)
+            if rv["index"] is not None and rv["index"] >= 0:
+                rv["value"] = self.make_int(tx_obj["vout"][rv["index"]]["value"])
 
         if return_txid:
             rv["txid"] = txid.hex()
diff --git a/basicswap/interface/nav.py b/basicswap/interface/nav.py
index 920d426..5d3a2f1 100644
--- a/basicswap/interface/nav.py
+++ b/basicswap/interface/nav.py
@@ -614,6 +614,8 @@ class NAVInterface(BTCInterface):
         if find_index:
             tx_obj = self.rpc("decoderawtransaction", [tx["hex"]])
             rv["index"] = find_vout_for_address_from_txobj(tx_obj, dest_address)
+            if rv["index"] is not None and rv["index"] >= 0:
+                rv["value"] = self.make_int(tx_obj["vout"][rv["index"]]["value"])
 
         if return_txid:
             rv["txid"] = txid.hex()