fix: mpay forbid self payments

tools/plugins/mpay/pay/invoice_check.py

@@ -6,6 +6,10 @@
 from plugins.hold.encoder import get_network_prefix
 
 
+class InvoiceNoSelfPaymentError(Exception):
+    pass
+
+
 class InvoiceNetworkInvalidError(Exception):
     pass
 
@@ -16,25 +20,32 @@ class InvoiceExpiredError(Exception):
 
 class InvoiceChecker:
     _pl: Plugin
+    _node_id: str
     _prefix: str
 
     def __init__(self, pl: Plugin) -> None:
         self._pl = pl
 
     def init(self) -> None:
         info = self._pl.rpc.getinfo()
+        self._node_id = info["id"]
         self._prefix = get_network_prefix(info["network"])
 
     def check(self, invoice: str) -> None:
         dec = decode(invoice)
 
         self._check_network(dec)
+        self._check_self_payment(dec)
         self._check_expiry(dec)
 
     def _check_network(self, dec: Bolt11) -> None:
         if dec.currency != self._prefix:
             raise InvoiceNetworkInvalidError
 
+    def _check_self_payment(self, dec: Bolt11) -> None:
+        if dec.payee == self._node_id:
+            raise InvoiceNoSelfPaymentError
+
     @staticmethod
     def _check_expiry(dec: Bolt11) -> None:
         if dec.date + dec.expiry <= int(time.time()):

tools/plugins/mpay/pay/tests/test_invoice_check.py

@@ -12,13 +12,17 @@
     InvoiceChecker,
     InvoiceExpiredError,
     InvoiceNetworkInvalidError,
+    InvoiceNoSelfPaymentError,
 )
 
 
 class RpcCaller:
     @staticmethod
     def getinfo() -> dict[str, str]:
-        return {"network": "regtest"}
+        return {
+            "id": "03b40f44ad0ebd864916bc2fdd424acc648a6373ace27b9f8d337edac498383982",
+            "network": "regtest",
+        }
 
 
 class RpcPlugin:
@@ -31,6 +35,7 @@ class TestInvoiceCheck:
     def test_init(self) -> None:
         self.checker.init()
         assert self.checker._prefix == "bcrt"  # noqa: SLF001
+        assert self.checker._node_id == RpcPlugin().rpc.getinfo()["id"]  # noqa: SLF001
 
     @pytest.mark.parametrize(
         ("ok", "invoice"),
@@ -56,6 +61,26 @@ def test_check_network(self, invoice: str, ok: bool) -> None:
             with pytest.raises(InvoiceNetworkInvalidError):
                 self.checker._check_network(decode(invoice))  # noqa: SLF001
 
+    @pytest.mark.parametrize(
+        ("ok", "invoice"),
+        [
+            (
+                True,
+                "lnbcrt1231230n1pjuwm72pp59sf47h44yjzl5x8w2v3v3gqctu6uad9zkwf9qnspxl6ajkeeq6eqdqqcqzzsxqyz5vqsp5wg079faqgp5pplt7nks643mqt0y6wwfsq5zetpm9dt4uuv5dj6yq9qyyssq6d9cdgr3v3ncq2yavcxyz4ku9yx399aqynw8s3dhm2tu00yy98n5urke94l59dn5pngpxysnzptyv9alrrq5rdr2pjj4dvpmt272j0cpszwkwq",
+            ),
+            (
+                False,
+                "lnbcrt1231231230p1pjuwma7sp5plj4ntddejnx8hc0l3xptagmvp32anz7hccxrzrr6xwsqrtyea3qpp5qjnz9rewdr5ly07ngw7kdf695jzrdt2cy2h043dlxt8yfdwnnk0qdq8v9ekgesxqyjw5qcqp2rzjq0kuk5cssreq495qpyf8q8v9dssd05ujxa3e7f5chk7pf0al6npevqqq0sqqqqgqqqqqqqlgqqqqqqgq2q9qxpqysgqz0w3la2mkkspuc2285x2wfcq479lg96z3fjy9exu05xzx4l5j8g9gww60237adryf5vpykxf2gxlqvtf00p98s5af02k8zac4440gzsq3cak6u",
+            ),
+        ],
+    )
+    def test_check_self_payment(self, invoice: str, ok: bool) -> None:
+        if ok:
+            self.checker._check_self_payment(decode(invoice))  # noqa: SLF001
+        else:
+            with pytest.raises(InvoiceNoSelfPaymentError):
+                self.checker._check_self_payment(decode(invoice))  # noqa: SLF001
+
     @pytest.mark.parametrize(
         ("ok", "invoice"),
         [