pay: split into getroute and sendpay

This is less convenient to use, but makes far more sense for a real
user (like a wallet).  It can ask about the route, then decide whether
to use it or not.

This will make even more sense once we add a parameter to control how
long we let the HTLC be delayed for, so a client can query for high,
medium and low tolerances and compare results.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

daemon/json.c

@@ -425,6 +425,17 @@ void json_add_hex(struct json_result *result, const char *fieldname,
 	json_add_string(result, fieldname, hex);
 }
 
+void json_add_pubkey(struct json_result *response,
+		     secp256k1_context *secpctx,
+		     const char *fieldname,
+		     const struct pubkey *key)
+{
+	u8 der[PUBKEY_DER_LEN];
+
+	pubkey_to_der(secpctx, der, key);
+	json_add_hex(response, fieldname, der, sizeof(der));
+}
+
 void json_add_object(struct json_result *result, ...)
 {
 	va_list ap;

daemon/json.h

@@ -1,6 +1,7 @@
 #ifndef LIGHTNING_DAEMON_JSON_H
 #define LIGHTNING_DAEMON_JSON_H
 #include "config.h"
+#include <bitcoin/pubkey.h>
 #include <ccan/tal/tal.h>
 #include <stdbool.h>
 #include <stdint.h>
@@ -98,6 +99,11 @@ void json_add_null(struct json_result *result, const char *fieldname);
 /* '"fieldname" : "0189abcdef..."' or "0189abcdef..." if fieldname is NULL */
 void json_add_hex(struct json_result *result, const char *fieldname,
 		  const void *data, size_t len);
+/* '"fieldname" : "0289abcdef..."' or "0289abcdef..." if fieldname is NULL */
+void json_add_pubkey(struct json_result *response,
+		     secp256k1_context *secpctx,
+		     const char *fieldname,
+		     const struct pubkey *key);
 
 void json_add_object(struct json_result *result, ...);
 

daemon/jsonrpc.c

@@ -290,7 +290,8 @@ static const struct json_command *cmdlist[] = {
 	&close_command,
 	&newaddr_command,
 	&accept_payment_command,
-	&pay_command,
+	&getroute_command,
+	&sendpay_command,
 	&feerate_command,
 	/* Developer/debugging options. */
 	&echo_command,

daemon/jsonrpc.h

@@ -74,6 +74,7 @@ extern const struct json_command output_command;
 extern const struct json_command accept_payment_command;
 extern const struct json_command add_route_command;
 extern const struct json_command routefail_command;
-extern const struct json_command pay_command;
+extern const struct json_command getroute_command;
+extern const struct json_command sendpay_command;
 extern const struct json_command feerate_command;
 #endif /* LIGHTNING_DAEMON_JSONRPC_H */

daemon/lightning-cli.c

@@ -96,11 +96,13 @@ int main(int argc, char *argv[])
 		      method, idstr);
 
 	for (i = 2; i < argc; i++) {
-		/* Numbers and bools are left unquoted,
+		/* Numbers, bools, objects and arrays are left unquoted,
 		 * and quoted things left alone. */
 		if (strspn(argv[i], "0123456789") == strlen(argv[i])
 		    || streq(argv[i], "true")
 		    || streq(argv[i], "false")
+		    || argv[i][0] == '{'
+		    || argv[i][0] == '['
 		    || argv[i][0] == '"')
 			tal_append_fmt(&cmd, "%s", argv[i]);
 		else

daemon/onion.c

@@ -16,41 +16,35 @@ static const u8 *to_onion(const tal_t *ctx, const Route *r)
 	return onion;
 }
 
-/* Create an onion for sending msatoshi_with_fees down path. */
+/* Create an onion for this path. */
 const u8 *onion_create(const tal_t *ctx,
 		       secp256k1_context *secpctx,
-		       struct node_connection **path,
-		       u64 msatoshi, s64 fees)
+		       const struct pubkey *ids,
+		       const u64 *amounts,
+		       size_t num_hops)
 {
 	Route *r = tal(ctx, Route);
-	int i;
-	u64 amount = msatoshi;
+	size_t i;
 
 	route__init(r);
-	r->n_steps = tal_count(path) + 1;
+	r->n_steps = num_hops + 1;
 	r->steps = tal_arr(r, RouteStep *, r->n_steps);
 
-	/* Create backwards, so we can get fees correct. */
-	for (i = tal_count(path) - 1; i >= 0; i--) {
+	for (i = 0; i < num_hops; i++) {
 		r->steps[i] = tal(r, RouteStep);
 		route_step__init(r->steps[i]);
 		r->steps[i]->next_case = ROUTE_STEP__NEXT_BITCOIN;
-		r->steps[i]->bitcoin = pubkey_to_proto(r, secpctx,
-						       &path[i]->dst->id);
-		r->steps[i]->amount = amount;
-		amount += connection_fee(path[i], amount);
+		r->steps[i]->bitcoin = pubkey_to_proto(r, secpctx, &ids[i]);
+		r->steps[i]->amount = amounts[i];
 	}
 
 	/* Now the stop marker. */
-	i = tal_count(path);
 	r->steps[i] = tal(r, RouteStep);
 	route_step__init(r->steps[i]);
 	r->steps[i]->next_case = ROUTE_STEP__NEXT_END;
 	r->steps[i]->end = true;
 	r->steps[i]->amount = 0;
 
-	assert(amount == msatoshi + fees);
-	
 	return to_onion(ctx, r);
 }
 

daemon/onion.h

@@ -15,6 +15,7 @@ RouteStep *onion_unwrap(struct peer *peer,
 /* Create an onion for sending msatoshi down path, paying fees. */
 const u8 *onion_create(const tal_t *ctx,
 		       secp256k1_context *secpctx,
-		       struct node_connection **path,
-		       u64 msatoshi, s64 fees);
+		       const struct pubkey *ids,
+		       const u64 *amounts,
+		       size_t num_hops);
 #endif /* LIGHTNING_DAEMON_ONION_H */

daemon/pay.c

@@ -15,7 +15,7 @@
 struct pay_command {
 	struct list_node list;
 	struct sha256 rhash;
-	u64 msatoshis, fee;
+	u64 msatoshis;
 	struct pubkey id;
 	/* Set if this is in progress. */
 	struct htlc *htlc;
@@ -110,29 +110,37 @@ static struct pay_command *find_pay_command(struct lightningd_state *dstate,
 	return NULL;
 }
 
-static void json_pay(struct command *cmd,
-		     const char *buffer, const jsmntok_t *params)
+static void json_add_route(struct json_result *response,
+			   secp256k1_context *secpctx,
+			   const struct pubkey *id,
+			   u64 amount, unsigned int delay)
+{
+	json_object_start(response, NULL);
+	json_add_pubkey(response, secpctx, "id", id);
+	json_add_u64(response, "msatoshis", amount);
+	json_add_num(response, "delay", delay);
+	json_object_end(response);
+}
+
+static void json_getroute(struct command *cmd,
+			  const char *buffer, const jsmntok_t *params)
 {
 	struct pubkey id;
-	jsmntok_t *idtok, *msatoshistok, *rhashtok;
-	unsigned int expiry;
+	jsmntok_t *idtok, *msatoshistok;
+	struct json_result *response;
 	int i;
 	u64 msatoshis;
 	s64 fee;
-	struct sha256 rhash;
 	struct node_connection **route;
 	struct peer *peer;
-	struct pay_command *pc;
-	const u8 *onion;
-	enum fail_error error_code;
-	const char *err;
+	u64 *amounts, total_amount;
+	unsigned int total_delay, *delays;
 
 	if (!json_get_params(buffer, params,
 			     "id", &idtok,
 			     "msatoshis", &msatoshistok,
-			     "rhash", &rhashtok,
 			     NULL)) {
-		command_fail(cmd, "Need id, msatoshis and rhash");
+		command_fail(cmd, "Need id and msatoshis");
 		return;
 	}
 
@@ -150,6 +158,79 @@ static void json_pay(struct command *cmd,
 		return;
 	}
 
+	peer = find_route(cmd->dstate, &id, msatoshis, &fee, &route);
+	if (!peer) {
+		command_fail(cmd, "no route found");
+		return;
+	}
+
+	/* Fees, delays need to be calculated backwards along route. */
+	amounts = tal_arr(cmd, u64, tal_count(route)+1);
+	delays = tal_arr(cmd, unsigned int, tal_count(route)+1);
+	total_amount = msatoshis;
+
+	total_delay = 0;
+	for (i = tal_count(route) - 1; i >= 0; i--) {
+		amounts[i+1] = total_amount;
+		total_amount += connection_fee(route[i], total_amount);
+
+		total_delay += route[i]->delay;
+		if (total_delay < route[i]->min_blocks)
+			total_delay = route[i]->min_blocks;
+		delays[i+1] = total_delay;
+	}
+	/* We don't charge ourselves any fees. */
+	amounts[0] = total_amount;
+	/* We do require delay though. */
+	total_delay += peer->nc->delay;
+	if (total_delay < peer->nc->min_blocks)
+		total_delay = peer->nc->min_blocks;
+	delays[0] = total_delay;
+
+	response = new_json_result(cmd);
+	json_object_start(response, NULL);
+	json_array_start(response, "route");
+	json_add_route(response, cmd->dstate->secpctx,
+		       peer->id, amounts[0], delays[0]);
+	for (i = 0; i < tal_count(route); i++)
+		json_add_route(response, cmd->dstate->secpctx,
+			       &route[i]->dst->id, amounts[i+1], delays[i+1]);
+	json_array_end(response);
+	json_object_end(response);
+	command_success(cmd, response);
+}
+
+const struct json_command getroute_command = {
+	"getroute",
+	json_getroute,
+	"Return route for {msatoshis} to {id}",
+	"Returns a {route} array of {id} {msatoshis} {delay}: msatoshis and delay (in blocks) is cumulative."
+};
+
+static void json_sendpay(struct command *cmd,
+			 const char *buffer, const jsmntok_t *params)
+{
+	struct pubkey *ids;
+	u64 *amounts;
+	jsmntok_t *routetok, *rhashtok;
+	const jsmntok_t *t, *end;
+	unsigned int delay;
+	size_t n_hops;
+	struct sha256 rhash;
+	struct peer *peer;
+	struct pay_command *pc;
+	const u8 *onion;
+	enum fail_error error_code;
+	const char *err;
+
+	if (!json_get_params(buffer, params,
+			     "route", &routetok,
+			     "rhash", &rhashtok,
+			     NULL)) {
+		command_fail(cmd, "Need route and rhash");
+		return;
+	}
+
 	if (!hex_decode(buffer + rhashtok->start,
 			rhashtok->end - rhashtok->start,
 			&rhash, sizeof(rhash))) {
@@ -159,9 +240,65 @@ static void json_pay(struct command *cmd,
 		return;
 	}
 
+	if (routetok->type != JSMN_ARRAY) {
+		command_fail(cmd, "'%.*s' is not an array",
+			     (int)(routetok->end - routetok->start),
+			     buffer + routetok->start);
+		return;
+	}
+
+	end = json_next(routetok);
+	n_hops = 0;
+	amounts = tal_arr(cmd, u64, n_hops);
+	ids = tal_arr(cmd, struct pubkey, n_hops);
+	for (t = routetok + 1; t < end; t = json_next(t)) {
+		const jsmntok_t *amttok, *idtok, *delaytok;
+
+		if (t->type != JSMN_OBJECT) {
+			command_fail(cmd, "route %zu '%.*s' is not an object",
+				     n_hops,
+				     (int)(t->end - t->start),
+				     buffer + t->start);
+			return;
+		}
+		amttok = json_get_member(buffer, t, "msatoshis");
+		idtok = json_get_member(buffer, t, "id");
+		delaytok = json_get_member(buffer, t, "delay");
+		if (!amttok || !idtok || !delaytok) {
+			command_fail(cmd, "route %zu needs msatoshis/id/delay",
+				     n_hops);
+			return;
+		}
+
+		tal_resize(&amounts, n_hops+1);
+		if (!json_tok_u64(buffer, amttok, &amounts[n_hops])) {
+			command_fail(cmd, "route %zu invalid msatoshis", n_hops);
+			return;
+		}
+		tal_resize(&ids, n_hops+1);
+		if (!pubkey_from_hexstr(cmd->dstate->secpctx,
+					buffer + idtok->start,
+					idtok->end - idtok->start,
+					&ids[n_hops])) {
+			command_fail(cmd, "route %zu invalid id", n_hops);
+			return;
+		}
+		/* Only need first delay. */
+		if (n_hops == 0 && !json_tok_number(buffer, delaytok, &delay)) {
+			command_fail(cmd, "route %zu invalid delay", n_hops);
+			return;
+		}
+		n_hops++;
+	}
+
+	if (n_hops == 0) {
+		command_fail(cmd, "Empty route");
+		return;
+	}
+
 	pc = find_pay_command(cmd->dstate, &rhash);
 	if (pc) {
-		log_debug(cmd->dstate->base_log, "json_pay: found previous");
+		log_debug(cmd->dstate->base_log, "json_sendpay: found previous");
 		if (pc->htlc) {
 			log_add(cmd->dstate->base_log, "... still in progress");
 			command_fail(cmd, "still in progress");
@@ -170,13 +307,13 @@ static void json_pay(struct command *cmd,
 		if (pc->rval) {
 			log_add(cmd->dstate->base_log, "... succeeded");
 			/* Must match successful payment parameters. */
-			if (pc->msatoshis != msatoshis) {
+			if (pc->msatoshis != amounts[n_hops-1]) {
 				command_fail(cmd,
 					     "already succeeded with amount %"
 					     PRIu64, pc->msatoshis);
 				return;
 			}
-			if (!structeq(&pc->id, &id)) {
+			if (!structeq(&pc->id, &ids[n_hops-1])) {
 				char *previd;
 				previd = pubkey_to_hexstr(cmd,
 							  cmd->dstate->secpctx,
@@ -192,38 +329,28 @@ static void json_pay(struct command *cmd,
 		log_add(cmd->dstate->base_log, "... retrying");
 	}
 
-	/* FIXME: Add fee param, check for excessive fee. */
-	peer = find_route(cmd->dstate, &id, msatoshis, &fee, &route);
+	peer = find_peer(cmd->dstate, &ids[0]);
 	if (!peer) {
-		command_fail(cmd, "no route found");
+		command_fail(cmd, "no connection to first peer found");
 		return;
 	}
 
-	expiry = 0;
-	for (i = tal_count(route) - 1; i >= 0; i--) {
-		expiry += route[i]->delay;
-		if (expiry < route[i]->min_blocks)
-			expiry = route[i]->min_blocks;
-	}
-	expiry += peer->nc->delay;
-	if (expiry < peer->nc->min_blocks)
-		expiry = peer->nc->min_blocks;
-
-	/* Expiry for HTLCs is absolute.  And add one to give some margin. */
-	expiry += get_block_height(cmd->dstate) + 1;
-
-	onion = onion_create(cmd, cmd->dstate->secpctx, route, msatoshis, fee);
+	/* Onion will carry us from first peer onwards. */
+	onion = onion_create(cmd, cmd->dstate->secpctx, ids+1, amounts+1,
+			     n_hops-1);
 
 	if (!pc)
 		pc = tal(cmd->dstate, struct pay_command);
 	pc->cmd = cmd;
 	pc->rhash = rhash;
 	pc->rval = NULL;
-	pc->id = id;
-	pc->msatoshis = msatoshis;
-	pc->fee = fee;
+	pc->id = ids[n_hops-1];
+	pc->msatoshis = amounts[n_hops-1];
 
-	err = command_htlc_add(peer, msatoshis + fee, expiry, &rhash, NULL,
+	/* Expiry for HTLCs is absolute.  And add one to give some margin. */
+	err = command_htlc_add(peer, amounts[0],
+			       delay + get_block_height(cmd->dstate) + 1,
+			       &rhash, NULL,
 			       onion, &error_code, &pc->htlc);
 	if (err) {
 		command_fail(cmd, "could not add htlc: %u: %s", error_code, err);
@@ -235,9 +362,9 @@ static void json_pay(struct command *cmd,
 	tal_add_destructor(cmd, remove_cmd_from_pc);
 }
 
-const struct json_command pay_command = {
-	"pay",
-	json_pay,
-	"Send {id} {msatoshis} in return for preimage of {rhash}",
+const struct json_command sendpay_command = {
+	"sendpay",
+	json_sendpay,
+	"Send along {route} in return for preimage of {rhash}",
 	"Returns the {preimage} on success"
 };

daemon/peer.c

@@ -4169,17 +4169,6 @@ static void json_add_abstime(struct json_result *response,
 	json_object_end(response);
 }
 
-static void json_add_pubkey(struct json_result *response,
-			    secp256k1_context *secpctx,
-			    const char *id,
-			    const struct pubkey *key)
-{
-	u8 der[PUBKEY_DER_LEN];
-
-	pubkey_to_der(secpctx, der, key);
-	json_add_hex(response, id, der, sizeof(der));
-}
-
 static void json_add_htlcs(struct json_result *response,
 			   const char *id,
 			   struct peer *peer,
@@ -4344,15 +4333,6 @@ void cleanup_peers(struct lightningd_state *dstate)
 	}
 }
 
-/* A zero-fee single route to this peer. */
-static const u8 *dummy_single_route(const tal_t *ctx,
-				    const struct peer *peer,
-				    u64 msatoshis)
-{
-	struct node_connection **path = tal_arr(ctx, struct node_connection *, 0);
-	return onion_create(ctx, peer->dstate->secpctx, path, msatoshis, 0);
-}
-
 static void json_newhtlc(struct command *cmd,
 			 const char *buffer, const jsmntok_t *params)
 {
@@ -4416,7 +4396,8 @@ static void json_newhtlc(struct command *cmd,
 
 	log_debug(peer->log, "JSON command to add new HTLC");
 	err = command_htlc_add(peer, msatoshis, expiry, &rhash, NULL,
-			       dummy_single_route(cmd, peer, msatoshis),
+			       onion_create(cmd, cmd->dstate->secpctx,
+					    NULL, NULL, 0),
 			       &error_code, &htlc);
 	if (err) {
 		command_fail(cmd, "could not add htlc: %u:%s", error_code, err);

daemon/test/test.sh

@@ -1011,20 +1011,26 @@ if [ ! -n "$MANUALCOMMIT" ]; then
     # FIXME: We don't save payments in db yet!
     DO_RECONNECT=""
 
+    # Get route.
+    ROUTE=`lcli1 getroute $ID3 $HTLC_AMOUNT`
+    ROUTE=`echo $ROUTE | sed 's/^{ "route" : \(.*\) }$/\1/'`
+
     # Try wrong hash.
-    if lcli1 pay $ID3 $HTLC_AMOUNT $RHASH4; then
+    if lcli1 sendpay "$ROUTE" $RHASH4; then
 	echo Paid with wrong hash? >&2
 	exit 1
     fi
 
     # Try underpaying.
-    if lcli1 pay $ID3 $(($HTLC_AMOUNT-1)) $RHASH5; then
+    PAID=`echo "$ROUTE" | sed -n 's/.*"msatoshis" : \([0-9]*\),.*/\1/p'`
+    UNDERPAY=`echo "$ROUTE" | sed "s/: $PAID,/: $(($PAID - 1)),/"`
+    if lcli1 sendpay "$UNDERPAY" $RHASH5; then
 	echo Paid with too little? >&2
 	exit 1
     fi
 
     # Pay correctly.
-    lcli1 pay $ID3 $HTLC_AMOUNT $RHASH5
+    lcli1 sendpay "$ROUTE" $RHASH5
 
     # Node 3 should end up with that amount (minus 1/2 tx fee)
     # Note that it is delayed a little, since node2 fulfils as soon as fulfill
@@ -1033,11 +1039,12 @@ if [ ! -n "$MANUALCOMMIT" ]; then
     lcli3 close $ID2
 
     # Re-send should be a noop (doesn't matter that node3 is down!)
-    lcli1 pay $ID3 $HTLC_AMOUNT $RHASH5
+    lcli1 sendpay "$ROUTE" $RHASH5
 
     # Re-send to different id or amount should complain.
-    lcli1 pay $ID2 $HTLC_AMOUNT $RHASH5 | $FGREP "already succeeded to $ID3"
-    lcli1 pay $ID2 $(($HTLC_AMOUNT + 1)) $RHASH5 | $FGREP "already succeeded with amount $HTLC_AMOUNT"
+    SHORTROUTE=`echo "$ROUTE" | sed 's/, { "id" : .* }//' | sed 's/"msatoshis" : [0-9]*,/"msatoshis" : '$HTLC_AMOUNT,/`
+    lcli1 sendpay "$SHORTROUTE" $RHASH5 | $FGREP "already succeeded to $ID3"
+    lcli1 sendpay "$UNDERPAY" $RHASH5 | $FGREP "already succeeded with amount $HTLC_AMOUNT"
 
     DO_RECONNECT=$RECONNECT
 fi