Forbid prioritizing a spend if...

...the cpfp key is missing

src/daemon/jsonrpc/api/mod.rs

@@ -1293,6 +1293,15 @@ impl RpcApi for RpcImpl {
         let revaultd = meta.rpc_utils.revaultd.read().unwrap();
         let db_path = revaultd.db_file();
 
+        if revaultd.cpfp_key.is_none() {
+            return Err(JsonRpcError::invalid_params(
+                "Can't read the cpfp key. \
+                    Make sure you have a file called cpfp_secret containing \
+                    the private key in your datadir"
+                    .to_string(),
+            ));
+        }
+
         // Get the referenced Spend and the vaults it spends from the DB
         let mut spend_tx = db_spend_transaction(&db_path, &spend_txid)
             .map_err(|e| Error::from(e))?

tests/test_rpc.py

@@ -1141,3 +1141,22 @@ def test_getserverstatus(revault_network, bitcoind):
             assert not cosigner["reachable"]
             # Sadly we don't persist the cosigner ports
             assert cosigner["host"].startswith("127.0.0.1:")
+
+
+@pytest.mark.skipif(not POSTGRES_IS_SETUP, reason="Needs Postgres for servers db")
+def test_setspendtx_cpfp_not_enabled(revault_network, bitcoind):
+    CSV = 12
+    revault_network.deploy(2, 1, n_stkmanagers=1, csv=CSV, cpfp_enabled=False)
+    man = revault_network.mans()[1]
+    stks = revault_network.stks()
+    amount = 0.24
+    vault = revault_network.fund(amount)
+    deposit = f"{vault['txid']}:{vault['vout']}"
+
+    revault_network.secure_vault(vault)
+    revault_network.activate_vault(vault)
+    with pytest.raises(
+        RpcError,
+        match="Can't read the cpfp key",
+    ):
+        revault_network.unvault_vaults_anyhow_unconfirmed([vault], priority=True)