keysend: try to find description in TLV.

"Who needs specs?" FFS... Signed-off-by: Rusty Russell <[email protected]> Changelog-Added: Protocol: `keysend` will now attach the longest valid text field in the onion to the invoice (so you can have Sphinx.chat users spam you!)
docallag · Sep 22, 2022 · ce0f544 · ce0f544
1 parent 41502be
commit ce0f544
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Showing 2 changed files with 42 additions and 11 deletions.
diff --git a/plugins/keysend.c b/plugins/keysend.c
@@ -341,9 +341,8 @@ static struct command_result *htlc_accepted_call(struct command *cmd,
 	struct sha256 payment_hash;
 	size_t max;
 	struct tlv_tlv_payload *payload;
-	struct tlv_field *preimage_field = NULL, *unknown_field = NULL;
+	struct tlv_field *preimage_field = NULL, *unknown_field = NULL, *desc_field = NULL;
 	bigsize_t s;
-	struct tlv_field *field;
 	struct keysend_in *ki;
 	struct out_req *req;
 	struct timeabs now = time_now();
@@ -387,15 +386,21 @@ static struct command_result *htlc_accepted_call(struct command *cmd,
 	}
 
 	/* Try looking for the field that contains the preimage */
-	for (int i=0; i<tal_count(payload->fields); i++) {
-		field = &payload->fields[i];
+	for (size_t i = 0; i < tal_count(payload->fields); i++) {
+		struct tlv_field *field = &payload->fields[i];
 		if (field->numtype == PREIMAGE_TLV_TYPE) {
 			preimage_field = field;
-			break;
+			continue;
 		} else if (field->numtype % 2 == 0 && field->meta == NULL) {
 			/* This can only happen with FROMWIRE_TLV_ANY_TYPE! */
 			unknown_field = field;
 		}
+
+		/* Longest (unknown) text field wins. */
+		if (!field->meta
+		    && utf8_check(field->value, field->length)
+		    && (!desc_field || field->length > desc_field->length))
+			desc_field = field;
 	}
 
 	/* If we don't have a preimage field then this is not a keysend, let
@@ -464,7 +469,17 @@ static struct command_result *htlc_accepted_call(struct command *cmd,
 	plugin_log(cmd->plugin, LOG_INFORM, "Inserting a new invoice for keysend with payment_hash %s", type_to_string(tmpctx, struct sha256, &payment_hash));
 	json_add_string(req->js, "amount_msat", "any");
 	json_add_string(req->js, "label", ki->label);
-	json_add_string(req->js, "description", "Spontaneous incoming payment through keysend");
+	if (desc_field) {
+		const char *desc = tal_fmt(tmpctx, "keysend: %.*s",
+					   (int)desc_field->length,
+					   (const char *)desc_field->value);
+		json_add_string(req->js, "description", desc);
+		/* Don't exceed max possible desc length! */
+		if (strlen(desc) > 1023)
+			json_add_bool(req->js, "deschashonly", true);
+	} else {
+		json_add_string(req->js, "description", "keysend");
+	}
 	json_add_preimage(req->js, "preimage", &ki->payment_preimage);
 
 	return send_outreq(cmd->plugin, req);

diff --git a/tests/test_pay.py b/tests/test_pay.py
@@ -3585,17 +3585,33 @@ def test_keysend_extra_tlvs(node_factory):
         ]
     )
 
-    # Send an indirect one from l1 to l3
     l1.rpc.keysend(l2.info['id'], amt, extratlvs={133773310: 'FEEDC0DE'})
-    invs = l2.rpc.listinvoices()['invoices']
-    assert(len(invs) == 1)
+    inv = only_one(l2.rpc.listinvoices()['invoices'])
     assert(l2.daemon.is_in_log(r'plugin-sphinx-receiver.py.*extratlvs.*133773310.*feedc0de'))
 
-    inv = invs[0]
     assert(inv['amount_received_msat'] >= Millisatoshi(amt))
+    assert inv['description'] == 'keysend'
+    l2.rpc.delinvoice(inv['label'], 'paid')
 
     # Now try again with the TLV type in extra_tlvs as string:
-    l1.rpc.keysend(l2.info['id'], amt, extratlvs={133773310: 'FEEDC0DE'})
+    l1.rpc.keysend(l2.info['id'], amt, extratlvs={133773310: b'hello there'.hex()})
+    inv = only_one(l2.rpc.listinvoices()['invoices'])
+    assert inv['description'] == 'keysend: hello there'
+    l2.rpc.delinvoice(inv['label'], 'paid')
+
+    # We can (just!) fit a giant description in.
+    l1.rpc.keysend(l2.info['id'], amt, extratlvs={133773310: (b'a' * 1100).hex()})
+    inv = only_one(l2.rpc.listinvoices()['invoices'])
+    assert inv['description'] == 'keysend: ' + 'a' * 1100
+    l2.rpc.delinvoice(inv['label'], 'paid')
+
+    # Now try with some special characters
+    ksinfo = """💕 ₿"'
+More info
+"""
+    l1.rpc.keysend(l2.info['id'], amt, extratlvs={133773310: bytes(ksinfo, encoding='utf8').hex()})
+    inv = only_one(l2.rpc.listinvoices()['invoices'])
+    assert inv['description'] == 'keysend: ' + ksinfo
 
 
 def test_keysend_routehint(node_factory):