paymod: Add a deadline to the pay command and retry modifier

plugins/libplugin-pay.c

@@ -36,6 +36,7 @@ struct payment *payment_new(tal_t *ctx, struct command *cmd,
 
 		/* Re-establish the unmodified constraints for our sub-payment. */
 		p->constraints = *parent->start_constraints;
+		p->deadline = parent->deadline;
 	} else {
 		assert(cmd != NULL);
 		p->partid = 0;
@@ -1317,10 +1318,21 @@ static inline void retry_step_cb(struct retry_mod_data *rd,
 {
 	struct payment *subpayment;
 	struct retry_mod_data *rdata = payment_mod_retry_get_data(p);
+	struct timeabs now = time_now();
 
 	if (p->step != PAYMENT_STEP_FAILED)
 		return payment_continue(p);
 
+	if (time_after(now, p->deadline)) {
+		plugin_log(
+		    p->plugin, LOG_INFORM,
+		    "Payment deadline expired, not retrying (partial-)payment "
+		    "%s/%d",
+		    type_to_string(tmpctx, struct sha256, p->payment_hash),
+		    p->partid);
+		return payment_continue(p);
+	}
+
 	/* If we failed to find a route, it's unlikely we can suddenly find a
 	 * new one without any other changes, so it's time to give up. */
 	if (p->route == NULL)
@@ -1928,3 +1940,68 @@ static struct direct_pay_data *direct_pay_init(struct payment *p)
 
 REGISTER_PAYMENT_MODIFIER(directpay, struct direct_pay_data *, direct_pay_init,
 			  direct_pay_cb);
+
+static struct command_result *waitblockheight_rpc_cb(struct command *cmd,
+						     const char *buffer,
+						     const jsmntok_t *toks,
+						     struct payment *p)
+{
+	struct payment *subpayment;
+	subpayment = payment_new(p, NULL, p, p->modifiers);
+	payment_start(subpayment);
+	payment_set_step(p, PAYMENT_STEP_RETRY);
+	subpayment->why =
+		tal_fmt(subpayment, "Retrying after waiting for blockchain sync.");
+	payment_continue(p);
+	return command_still_pending(cmd);
+}
+
+static void waitblockheight_cb(void *d, struct payment *p)
+{
+	struct out_req *req;
+	struct timeabs now = time_now();
+	struct timerel remaining;
+	u32 blockheight;
+	int failcode;
+	const u8 *raw_message;
+	if (p->step != PAYMENT_STEP_FAILED)
+		return payment_continue(p);
+
+	/* If we don't have an error message to parse we can't wait for blockheight. */
+	if (p->result == NULL)
+		return payment_continue(p);
+
+	if (time_after(now, p->deadline))
+		return payment_continue(p);
+
+	failcode = p->result->failcode;
+	raw_message = p->result->raw_message;
+	remaining = time_between(p->deadline, now);
+
+	if (failcode != 17 /* Former final_expiry_too_soon */) {
+		blockheight = p->start_block + 1;
+	}  else {
+		/* If it's incorrect_or_unknown_payment_details, that tells us
+		 * what height they're at */
+		struct amount_msat unused;
+		const void *ptr = raw_message;
+		if (!fromwire_incorrect_or_unknown_payment_details(
+			ptr, &unused, &blockheight))
+			return payment_continue(p);
+	}
+
+	plugin_log(p->plugin, LOG_INFORM,
+		   "Remote node appears to be on a longer chain, which causes "
+		   "CLTV timeouts to be incorrect. Waiting up to %" PRIu64
+		   " seconds to catch up to block %d before retrying.",
+		   time_to_sec(remaining), blockheight);
+
+	req = jsonrpc_request_start(p->plugin, NULL, "waitblockheight",
+				    waitblockheight_rpc_cb,
+				    waitblockheight_rpc_cb, p);
+	json_add_u32(req->js, "blockheight", blockheight);
+	json_add_u32(req->js, "timeout", time_to_sec(remaining));
+	send_outreq(p->plugin, req);
+}
+
+REGISTER_PAYMENT_MODIFIER(waitblockheight, void *, NULL, waitblockheight_cb);

plugins/libplugin-pay.h

@@ -317,6 +317,7 @@ REGISTER_PAYMENT_MODIFIER_HEADER(routehints, struct routehints_data);
 REGISTER_PAYMENT_MODIFIER_HEADER(exemptfee, struct exemptfee_data);
 REGISTER_PAYMENT_MODIFIER_HEADER(shadowroute, struct shadow_route_data);
 REGISTER_PAYMENT_MODIFIER_HEADER(directpay, struct direct_pay_data);
+extern struct payment_modifier waitblockheight_pay_mod;
 
 /* For the root payment we can seed the channel_hints with the result from
  * `listpeers`, hence avoid channels that we know have insufficient capacity

plugins/pay.c

@@ -1842,6 +1842,7 @@ struct payment_modifier *paymod_mods[] = {
 	&shadowroute_pay_mod,
 	&exemptfee_pay_mod,
 	&routehints_pay_mod,
+	&waitblockheight_pay_mod,
 	&retry_pay_mod,
 	NULL,
 };
@@ -1861,6 +1862,7 @@ static struct command_result *json_paymod(struct command *cmd,
 	u32 *maxdelay;
 	struct amount_msat *exemptfee, *msat;
 	const char *label;
+	unsigned int *retryfor;
 #if DEVELOPER
 	bool *use_shadow;
 #endif
@@ -1876,6 +1878,7 @@ static struct command_result *json_paymod(struct command *cmd,
 		   p_opt_def("exemptfee", param_msat, &exemptfee, AMOUNT_MSAT(5000)),
 		   p_opt_def("maxdelay", param_number, &maxdelay,
 			     maxdelay_default),
+		   p_opt_def("retry_for", param_number, &retryfor, 60),
 		   p_opt_def("maxfeepercent", param_millionths,
 			     &maxfee_pct_millionths, 500000),
 #if DEVELOPER
@@ -1933,6 +1936,7 @@ static struct command_result *json_paymod(struct command *cmd,
 	p->bolt11 = tal_steal(p, b11str);
 	p->why = "Initial attempt";
 	p->constraints.cltv_budget = *maxdelay;
+	p->deadline = timeabs_add(time_now(), time_from_sec(*retryfor));
 
 	if (!amount_msat_fee(&p->constraints.fee_budget, p->amount, 0,
 			     *maxfee_pct_millionths / 100)) {

tests/test_pay.py

@@ -3077,7 +3077,7 @@ def test_pay_modifiers(node_factory):
     # Make sure that the dummy param is in the help (and therefore assigned to
     # the modifier data).
     hlp = l1.rpc.help("paymod")['help'][0]
-    assert(hlp['command'] == 'paymod bolt11 [msatoshi] [label] [exemptfee] [maxdelay] [maxfeepercent] [use_shadow]')
+    assert(hlp['command'] == 'paymod bolt11 [msatoshi] [label] [exemptfee] [maxdelay] [retry_for] [maxfeepercent] [use_shadow]')
 
     inv = l2.rpc.invoice(123, 'lbl', 'desc')['bolt11']
     r = l1.rpc.paymod(inv)