Merge bitcoin/bitcoin#26344: wallet: Fix sendall with watchonly wallets and specified inputs

315fd4dbabb6b631b755811742a3bdf93e1241bf test: Test for out of bounds vout in sendall (Andrew Chow)
b132c85650afb2182f2e58e903f3d6f86fd3fb22 wallet: Check utxo prevout index out of bounds in sendall (Andrew Chow)
708b72b7151c855cb5dac2fb6a81e8f35153c46f test: Test that sendall works with watchonly spending specific utxos (Andrew Chow)
6bcd7e2a3b52f855db84cd23b5ee70d27be3434f wallet: Correctly check ismine for sendall (Andrew Chow)

Pull request description:

  The `sendall` RPC would previously fail when used with a watchonly wallet and specified inputs. This failure was caused by checking isminetype equality with ISMINE_ALL rather than a bitwise AND as IsMine can never return ISMINE_ALL.

  Also added a test.

ACKs for top commit:
  w0xlt:
    ACK https://github.com/bitcoin/bitcoin/pull/26344/commits/315fd4dbabb6b631b755811742a3bdf93e1241bf
  furszy:
    ACK 315fd4db

Tree-SHA512: fb55cf6524e789964770b803f401027319f0351433ea084ffa7c5e6f1797567a608c956b7f7c5bd542aa172c4b7b38b07d0976f5ec587569efead27266e8664c

2 files changed, 36 insertions, 1 deletions

diff --git a/src/wallet/rpc/spend.cpp b/src/wallet/rpc/spend.cpp
index ebf694157b..6cb33fc11e 100644
--- a/src/wallet/rpc/spend.cpp
+++ b/src/wallet/rpc/spend.cpp
@@ -1379,7 +1379,7 @@ RPCHelpMan sendall()
                         throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Input not available. UTXO (%s:%d) was already spent.", input.prevout.hash.ToString(), input.prevout.n));
                     }
                     const CWalletTx* tx{pwallet->GetWalletTx(input.prevout.hash)};
-                    if (!tx || pwallet->IsMine(tx->tx->vout[input.prevout.n]) != (coin_control.fAllowWatchOnly ? ISMINE_ALL : ISMINE_SPENDABLE)) {
+                    if (!tx || input.prevout.n >= tx->tx->vout.size() || !(pwallet->IsMine(tx->tx->vout[input.prevout.n]) & (coin_control.fAllowWatchOnly ? ISMINE_ALL : ISMINE_SPENDABLE))) {
                         throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Input not found. UTXO (%s:%d) is not part of wallet.", input.prevout.hash.ToString(), input.prevout.n));
                     }
                     total_input_value += tx->tx->vout[input.prevout.n].nValue;
diff --git a/test/functional/wallet_sendall.py b/test/functional/wallet_sendall.py
index db4f32fe16..4fe11455b1 100755
--- a/test/functional/wallet_sendall.py
+++ b/test/functional/wallet_sendall.py
@@ -221,6 +221,11 @@ class SendallTest(BitcoinTestFramework):
         self.add_utxos([16, 5])
         spent_utxo = self.wallet.listunspent()[0]
 
+        # fails on out of bounds vout
+        assert_raises_rpc_error(-8,
+                "Input not found. UTXO ({}:{}) is not part of wallet.".format(spent_utxo["txid"], 1000),
+                self.wallet.sendall, recipients=[self.remainder_target], options={"inputs": [{"txid": spent_utxo["txid"], "vout": 1000}]})
+
         # fails on unconfirmed spent UTXO
         self.wallet.sendall(recipients=[self.remainder_target])
         assert_raises_rpc_error(-8,
@@ -276,6 +281,33 @@ class SendallTest(BitcoinTestFramework):
                 recipients=[self.remainder_target],
                 fee_rate=100000)
 
+    @cleanup
+    def sendall_watchonly_specific_inputs(self):
+        self.log.info("Test sendall with a subset of UTXO pool in a watchonly wallet")
+        self.add_utxos([17, 4])
+        utxo = self.wallet.listunspent()[0]
+
+        self.nodes[0].createwallet(wallet_name="watching", disable_private_keys=True)
+        watchonly = self.nodes[0].get_wallet_rpc("watching")
+
+        import_req = [{
+            "desc": utxo["desc"],
+            "timestamp": 0,
+        }]
+        if self.options.descriptors:
+            watchonly.importdescriptors(import_req)
+        else:
+            watchonly.importmulti(import_req)
+
+        sendall_tx_receipt = watchonly.sendall(recipients=[self.remainder_target], options={"inputs": [utxo]})
+        psbt = sendall_tx_receipt["psbt"]
+        decoded = self.nodes[0].decodepsbt(psbt)
+        assert_equal(len(decoded["inputs"]), 1)
+        assert_equal(len(decoded["outputs"]), 1)
+        assert_equal(decoded["tx"]["vin"][0]["txid"], utxo["txid"])
+        assert_equal(decoded["tx"]["vin"][0]["vout"], utxo["vout"])
+        assert_equal(decoded["tx"]["vout"][0]["scriptPubKey"]["address"], self.remainder_target)
+
     # This tests needs to be the last one otherwise @cleanup will fail with "Transaction too large" error
     def sendall_fails_with_transaction_too_large(self):
         self.log.info("Test that sendall fails if resulting transaction is too large")
@@ -341,6 +373,9 @@ class SendallTest(BitcoinTestFramework):
         # Sendall fails when providing a fee that is too high
         self.sendall_fails_on_high_fee()
 
+        # Sendall succeeds with watchonly wallets spending specific UTXOs
+        self.sendall_watchonly_specific_inputs()
+
         # Sendall fails when many inputs result to too large transaction
         self.sendall_fails_with_transaction_too_large()