waitsendpay: indicate which channel direction the error was.

You can figure this yourself by knowing the route, but it's better to report
it directly here.

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

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 - plugins: fully enabled, and ready for you to write some!
 - lightning-cli: `help <cmd>` finds man pages even if `make install` not run.
+- JSON API: `waitsendpay` now has an `erring_channel_direction` field.
 
 ### Changed
 

bitcoin/pubkey.h

@@ -45,6 +45,12 @@ void pubkey_to_der(u8 der[PUBKEY_DER_LEN], const struct pubkey *key);
 /* Compare the keys `a` and `b`. Return <0 if `a`<`b`, 0 if equal and >0 otherwise */
 int pubkey_cmp(const struct pubkey *a, const struct pubkey *b);
 
+/* If the two nodes[] are id1 and id2, which index would id1 be? */
+static inline int pubkey_idx(const struct pubkey *id1, const struct pubkey *id2)
+{
+	return pubkey_cmp(id1, id2) > 0;
+}
+
 /**
  * pubkey_to_hash160 - Get the hash for p2pkh payments for a given pubkey
  */

gossipd/routing.h

@@ -136,12 +136,6 @@ HTABLE_DEFINE_TYPE(struct node, node_map_keyof_node, node_map_hash_key, node_map
 struct pending_node_map;
 struct pending_cannouncement;
 
-/* If the two nodes[] are id1 and id2, which index would id1 be? */
-static inline int pubkey_idx(const struct pubkey *id1, const struct pubkey *id2)
-{
-	return pubkey_cmp(id1, id2) > 0;
-}
-
 /* Fast versions: if you know n is one end of the channel */
 static inline struct node *other_node(const struct node *n,
 				      const struct chan *chan)

lightningd/pay.c

@@ -252,7 +252,8 @@ static struct routing_failure*
 immediate_routing_failure(const tal_t *ctx,
 			  const struct lightningd *ld,
 			  enum onion_type failcode,
-			  const struct short_channel_id *channel0)
+			  const struct short_channel_id *channel0,
+			  const struct pubkey *dstid)
 {
 	struct routing_failure *routing_failure;
 
@@ -263,6 +264,11 @@ immediate_routing_failure(const tal_t *ctx,
 	routing_failure->failcode = failcode;
 	routing_failure->erring_node = ld->id;
 	routing_failure->erring_channel = *channel0;
+	if (dstid)
+		routing_failure->channel_dir = pubkey_idx(&ld->id, dstid);
+	/* FIXME: Don't set at all unless we know. */
+	else
+		routing_failure->channel_dir = 0;
 	routing_failure->channel_update = NULL;
 
 	return routing_failure;
@@ -285,6 +291,8 @@ local_routing_failure(const tal_t *ctx,
 	routing_failure->failcode = hout->failcode;
 	routing_failure->erring_node = ld->id;
 	routing_failure->erring_channel = payment->route_channels[0];
+	routing_failure->channel_dir = pubkey_idx(&ld->id,
+						  &payment->route_nodes[0]);
 	routing_failure->channel_update = NULL;
 
 	return routing_failure;
@@ -313,6 +321,7 @@ remote_routing_failure(const tal_t *ctx,
 	int origin_index;
 	bool retry_plausible;
 	bool report_to_gossipd;
+	int dir;
 
 	routing_failure = tal(ctx, struct routing_failure);
 	route_nodes = payment->route_nodes;
@@ -333,7 +342,10 @@ remote_routing_failure(const tal_t *ctx,
 
 	/* Check if at destination. */
 	if (origin_index == tal_count(route_nodes) - 1) {
+		/* FIXME: Don't set erring_channel or dir in this case! */
 		erring_channel = &dummy_channel;
+		dir = 0;
+
 		/* BOLT #4:
 		 *
 		 * - if the _final node_ is returning the error:
@@ -356,6 +368,9 @@ remote_routing_failure(const tal_t *ctx,
 		/* Report the *next* channel as failing. */
 		erring_channel = &route_channels[origin_index + 1];
 
+		dir = pubkey_idx(&route_nodes[origin_index],
+				 &route_nodes[origin_index+1]);
+
 		/* If the error is a BADONION, then it's on behalf of the
 		 * following node. */
 		if (failcode & BADONION) {
@@ -371,6 +386,7 @@ remote_routing_failure(const tal_t *ctx,
 	routing_failure->erring_node = *erring_node;
 	routing_failure->erring_channel = *erring_channel;
 	routing_failure->channel_update = channel_update;
+	routing_failure->channel_dir = dir;
 
 	*p_retry_plausible = retry_plausible;
 	*p_report_to_gossipd = report_to_gossipd;
@@ -559,7 +575,8 @@ void payment_failed(struct lightningd *ld, const struct htlc_out *hout,
 				    fail ? &fail->erring_node : NULL,
 				    fail ? &fail->erring_channel : NULL,
 				    fail ? fail->channel_update : NULL,
-				    failmsg);
+				    failmsg,
+				    fail ? fail->channel_dir : 0);
 
 	/* Report to gossipd if we decided we should. */
 	if (report_to_gossipd)
@@ -595,6 +612,7 @@ bool wait_payment(const tal_t *cxt,
 	u8 *failupdate;
 	char *faildetail;
 	struct routing_failure *fail;
+	int faildirection;
 
 	payment = wallet_payment_by_hash(tmpctx, ld->wallet, payment_hash);
 	if (!payment) {
@@ -634,7 +652,8 @@ bool wait_payment(const tal_t *cxt,
 					    &failnode,
 					    &failchannel,
 					    &failupdate,
-					    &faildetail);
+					    &faildetail,
+					    &faildirection);
 		/* Old DB might not save failure information */
 		if (!failonionreply && !failnode)
 			result = sendpay_result_simple_fail(tmpctx,
@@ -653,6 +672,7 @@ bool wait_payment(const tal_t *cxt,
 			fail->erring_node = *failnode;
 			fail->erring_channel = *failchannel;
 			fail->channel_update = failupdate;
+			fail->channel_dir = faildirection;
 			result = sendpay_result_route_failure(tmpctx, !faildestperm, fail, NULL, faildetail);
 		}
 
@@ -770,7 +790,8 @@ send_payment(const tal_t *ctx,
 		/* Report routing failure to gossipd */
 		fail = immediate_routing_failure(ctx, ld,
 						 WIRE_UNKNOWN_NEXT_PEER,
-						 &route[0].channel_id);
+						 &route[0].channel_id,
+						 0);
 		report_routing_failure(ld->log, ld->gossip, fail);
 
 		/* Report routing failure to caller */
@@ -798,7 +819,8 @@ send_payment(const tal_t *ctx,
 		/* Report routing failure to gossipd */
 		fail = immediate_routing_failure(ctx, ld,
 						 failcode,
-						 &route[0].channel_id);
+						 &route[0].channel_id,
+						 &channel->peer->id);
 		report_routing_failure(ld->log, ld->gossip, fail);
 
 		/* Report routing failure to caller */
@@ -922,6 +944,8 @@ static void json_waitsendpay_on_resolve(const struct sendpay_result *r,
 			json_add_pubkey(data, "erring_node", &fail->erring_node);
 			json_add_short_channel_id(data, "erring_channel",
 						  &fail->erring_channel);
+			json_add_num(data, "erring_channel_direction",
+				     fail->channel_dir);
 			if (fail->channel_update)
 				json_add_hex_talarr(data, "channel_update",
 						    fail->channel_update);

lightningd/pay.h

@@ -19,6 +19,7 @@ struct routing_failure {
 	enum onion_type failcode;
 	struct pubkey erring_node;
 	struct short_channel_id erring_channel;
+	int channel_dir;
 	u8 *channel_update;
 };
 

wallet/db.c

@@ -354,6 +354,8 @@ char *dbmigrations[] = {
     ", state INTEGER"
     ", UNIQUE(in_htlc_id, out_htlc_id)"
     ");",
+    /* Add a direction for failed payments. */
+    "ALTER TABLE payments ADD faildirection INTEGER;", /* erring_direction */
     NULL,
 };
 

wallet/wallet.c

@@ -1838,7 +1838,8 @@ void wallet_payment_get_failinfo(const tal_t *ctx,
 				 struct pubkey **failnode,
 				 struct short_channel_id **failchannel,
 				 u8 **failupdate,
-				 char **faildetail)
+				 char **faildetail,
+				 int *faildirection)
 {
 	sqlite3_stmt *stmt;
 	int res;
@@ -1849,7 +1850,7 @@ void wallet_payment_get_failinfo(const tal_t *ctx,
 			  "SELECT failonionreply, faildestperm"
 			  "     , failindex, failcode"
 			  "     , failnode, failchannel"
-			  "     , failupdate, faildetail"
+			  "     , failupdate, faildetail, faildirection"
 			  "  FROM payments"
 			  " WHERE payment_hash=?;");
 	sqlite3_bind_sha256(stmt, 1, payment_hash);
@@ -1878,6 +1879,9 @@ void wallet_payment_get_failinfo(const tal_t *ctx,
 		*failchannel = tal(ctx, struct short_channel_id);
 		resb = sqlite3_column_short_channel_id(stmt, 5, *failchannel);
 		assert(resb);
+
+		/* For pre-0.6.2 dbs, direction will be 0 */
+		*faildirection = sqlite3_column_int(stmt, 8);
 	}
 	if (sqlite3_column_type(stmt, 6) == SQLITE_NULL)
 		*failupdate = NULL;
@@ -1901,7 +1905,8 @@ void wallet_payment_set_failinfo(struct wallet *wallet,
 				 const struct pubkey *failnode,
 				 const struct short_channel_id *failchannel,
 				 const u8 *failupdate /*tal_arr*/,
-				 const char *faildetail)
+				 const char *faildetail,
+				 int faildirection)
 {
 	sqlite3_stmt *stmt;
 
@@ -1915,6 +1920,7 @@ void wallet_payment_set_failinfo(struct wallet *wallet,
 			  "     , failchannel=?"
 			  "     , failupdate=?"
 			  "     , faildetail=?"
+			  "     , faildirection=?"
 			  " WHERE payment_hash=?;");
 	if (failonionreply)
 		sqlite3_bind_blob(stmt, 1,
@@ -1935,8 +1941,11 @@ void wallet_payment_set_failinfo(struct wallet *wallet,
 		struct short_channel_id *scid = tal(tmpctx, struct short_channel_id);
 		*scid = *failchannel;
 		sqlite3_bind_short_channel_id(stmt, 6, scid);
-	} else
+		sqlite3_bind_int(stmt, 9, faildirection);
+	} else {
 		sqlite3_bind_null(stmt, 6);
+		sqlite3_bind_null(stmt, 9);
+	}
 	if (failupdate)
 		sqlite3_bind_blob(stmt, 7,
 				  failupdate, tal_count(failupdate),
@@ -1947,7 +1956,7 @@ void wallet_payment_set_failinfo(struct wallet *wallet,
 			  faildetail, strlen(faildetail),
 			  SQLITE_TRANSIENT);
 
-	sqlite3_bind_sha256(stmt, 9, payment_hash);
+	sqlite3_bind_sha256(stmt, 10, payment_hash);
 
 	db_exec_prepared(wallet->db, stmt);
 }

wallet/wallet.h

@@ -883,7 +883,8 @@ void wallet_payment_set_status(struct wallet *wallet,
  * wallet_payment_get_failinfo - Get failure information for a given
  * `payment_hash`.
  *
- * Data is allocated as children of the given context.
+ * Data is allocated as children of the given context. *faildirection
+ * is only set if *failchannel is set non-NULL.
  */
 void wallet_payment_get_failinfo(const tal_t *ctx,
 				 struct wallet *wallet,
@@ -896,7 +897,8 @@ void wallet_payment_get_failinfo(const tal_t *ctx,
 				 struct pubkey **failnode,
 				 struct short_channel_id **failchannel,
 				 u8 **failupdate,
-				 char **faildetail);
+				 char **faildetail,
+				 int *faildirection);
 /**
  * wallet_payment_set_failinfo - Set failure information for a given
  * `payment_hash`.
@@ -910,7 +912,8 @@ void wallet_payment_set_failinfo(struct wallet *wallet,
 				 const struct pubkey *failnode,
 				 const struct short_channel_id *failchannel,
 				 const u8 *failupdate,
-				 const char *faildetail);
+				 const char *faildetail,
+				 int faildirection);
 
 /**
  * wallet_payment_list - Retrieve a list of payments