pay: add a dev-only parameter to deactivate shadow routing

Had to make a special pylightning function to avoid rewriting all calls
to 'pay()' with 'rpc.call()' in the next commit..

contrib/pylightning/lightning/lightning.py

@@ -434,6 +434,28 @@ class LightningRpc(UnixDomainSocketRpc):
         """
         return self.call("dev-memleak")
 
+    def dev_pay(self, bolt11, msatoshi=None, label=None, riskfactor=None,
+                description=None, maxfeepercent=None, retry_for=None,
+                maxdelay=None, exemptfee=None, use_shadow=True):
+        """
+        A developer version of `pay`, with the possibility to deactivate
+        shadow routing (used for testing).
+        """
+        payload = {
+            "bolt11": bolt11,
+            "msatoshi": msatoshi,
+            "label": label,
+            "riskfactor": riskfactor,
+            "maxfeepercent": maxfeepercent,
+            "retry_for": retry_for,
+            "maxdelay": maxdelay,
+            "exemptfee": exemptfee,
+            "use_shadow": use_shadow,
+            # Deprecated.
+            "description": description,
+        }
+        return self.call("pay", payload)
+
     def dev_reenable_commit(self, peer_id):
         """
         Re-enable the commit timer on peer {id}
@@ -761,7 +783,9 @@ class LightningRpc(UnixDomainSocketRpc):
         """
         return self.call("newaddr", {"addresstype": addresstype})
 
-    def pay(self, bolt11, msatoshi=None, label=None, riskfactor=None, description=None):
+    def pay(self, bolt11, msatoshi=None, label=None, riskfactor=None,
+            description=None, maxfeepercent=None, retry_for=None,
+            maxdelay=None, exemptfee=None):
         """
         Send payment specified by {bolt11} with {msatoshi}
         (ignored if {bolt11} has an amount), optional {label}
@@ -772,6 +796,10 @@ class LightningRpc(UnixDomainSocketRpc):
             "msatoshi": msatoshi,
             "label": label,
             "riskfactor": riskfactor,
+            "maxfeepercent": maxfeepercent,
+            "retry_for": retry_for,
+            "maxdelay": maxdelay,
+            "exemptfee": exemptfee,
             # Deprecated.
             "description": description,
         }

plugins/pay.c

@@ -103,6 +103,11 @@ struct pay_command {
 	/* Any remaining routehints to try. */
 	struct route_info **routehints;
 
+#if DEVELOPER
+	/* Disable the use of shadow route ? */
+	double use_shadow;
+#endif
+
 	/* Current node during shadow route calculation. */
 	const char *shadow_dest;
 };
@@ -873,6 +878,10 @@ static struct command_result *add_shadow_route(struct command *cmd,
 static struct command_result *shadow_route(struct command *cmd,
 					   struct pay_command *pc)
 {
+#if DEVELOPER
+	if (!pc->use_shadow)
+		return start_pay_attempt(cmd, pc, "Initial attempt");
+#endif
 	if (pseudorand(2) == 0)
 		return start_pay_attempt(cmd, pc, "Initial attempt");
 
@@ -1034,6 +1043,9 @@ static struct command_result *json_pay(struct command *cmd,
 	double *maxfeepercent;
 	unsigned int *maxdelay;
 	struct amount_msat *exemptfee;
+#if DEVELOPER
+	bool *use_shadow;
+#endif
 
 	if (!param(cmd, buf, params,
 		   p_req("bolt11", param_string, &b11str),
@@ -1045,6 +1057,9 @@ static struct command_result *json_pay(struct command *cmd,
 		   p_opt_def("maxdelay", param_number, &maxdelay,
 			     maxdelay_default),
 		   p_opt_def("exemptfee", param_msat, &exemptfee, AMOUNT_MSAT(5000)),
+#if DEVELOPER
+		   p_opt_def("use_shadow", param_bool, &use_shadow, true),
+#endif
 		   NULL))
 		return command_param_failed();
 
@@ -1096,6 +1111,9 @@ static struct command_result *json_pay(struct command *cmd,
 	pc->current_routehint = NULL;
 	pc->routehints = filter_routehints(pc, b11->routes);
 	pc->expensive_route = NULL;
+#if DEVELOPER
+	pc->use_shadow = *use_shadow;
+#endif
 
 	/* Get capacities of local channels (no parameters) */
 	return send_outreq(cmd, "listpeers", listpeers_done, forward_error, pc,

tests/test_plugin.py

@@ -239,8 +239,11 @@ def test_pay_plugin(node_factory):
         l1.rpc.call('pay')
 
     # Make sure usage messages are present.
-    assert only_one(l1.rpc.help('pay')['help'])['command'] == 'pay bolt11 [msatoshi] [label] [riskfactor] [maxfeepercent] [retry_for] [maxdelay] [exemptfee]'
+    msg = 'pay bolt11 [msatoshi] [label] [riskfactor] [maxfeepercent] '\
-    assert only_one(l1.rpc.help('paystatus')['help'])['command'] == 'paystatus [bolt11]'
+          '[retry_for] [maxdelay] [exemptfee]'
+    if DEVELOPER:
+        msg += ' [use_shadow]'
+    assert only_one(l1.rpc.help('pay')['help'])['command'] == msg
 
 
 def test_plugin_connected_hook(node_factory):