invoice: Properly implement waitinvoice.

Fixes: #444

lightningd/invoice.c

@@ -86,6 +86,10 @@ static void tell_waiter(struct command *cmd, const struct invoice *paid)
 	json_object_end(response);
 	command_success(cmd, response);
 }
+static void tell_waiter_deleted(struct command *cmd, const struct invoice *paid)
+{
+	command_fail(cmd, "invoice deleted during wait");
+}
 
 void resolve_invoice(struct lightningd *ld, struct invoice *invoice)
 {
@@ -94,11 +98,16 @@ void resolve_invoice(struct lightningd *ld, struct invoice *invoice)
 
 	invoice->state = PAID;
 
-	/* Tell all the waiters about the new paid invoice */
+	/* Tell all the waitanyinvoice waiters about the new paid invoice */
 	while ((w = list_pop(&invs->invoice_waiters,
 			     struct invoice_waiter,
 			     list)) != NULL)
 		tell_waiter(w->cmd, invoice);
+	/* Tell any waitinvoice waiters about the invoice getting paid. */
+	while ((w = list_pop(&invoice->invoice_waiters,
+			     struct invoice_waiter,
+			     list)) != NULL)
+		tell_waiter(w->cmd, invoice);
 
 	wallet_invoice_save(ld->wallet, invoice);
 
@@ -131,11 +140,21 @@ static char *delete_invoice(const tal_t *cxt,
 			    struct invoices *invs,
 			    struct invoice *i)
 {
+	struct invoice_waiter *w;
 	if (!wallet_invoice_remove(wallet, i)) {
 		return tal_strdup(cxt, "Database error");
 	}
 	list_del_from(&invs->invlist, &i->list);
 
+	/* Tell all the waiters about the fact that it was deleted. */
+	while ((w = list_pop(&i->invoice_waiters,
+			     struct invoice_waiter,
+			     list)) != NULL) {
+		tell_waiter_deleted(w->cmd, i);
+		/* No need to free w: w is a sub-object of cmd,
+		 * and tell_waiter_deleted also deletes the cmd. */
+	}
+
 	tal_free(i);
 	return NULL;
 }
@@ -165,6 +184,7 @@ static void json_invoice(struct command *cmd,
 	invoice = tal(cmd, struct invoice);
 	invoice->id = 0;
 	invoice->state = UNPAID;
+	list_head_init(&invoice->invoice_waiters);
 	randombytes_buf(invoice->r.r, sizeof(invoice->r.r));
 
 	sha256(&invoice->rhash, invoice->r.r, sizeof(invoice->r.r));
@@ -472,7 +492,7 @@ static void json_waitinvoice(struct command *cmd,
 		/* There is an unpaid one matching, let's wait... */
 		w = tal(cmd, struct invoice_waiter);
 		w->cmd = cmd;
-		list_add_tail(&invs->invoice_waiters, &w->list);
+		list_add_tail(&i->invoice_waiters, &w->list);
 		command_still_pending(cmd);
 	}
 }

lightningd/invoice.h

@@ -25,6 +25,7 @@ struct invoice {
 	struct preimage r;
 	u64 expiry_time;
 	struct sha256 rhash;
+	struct list_head invoice_waiters;
 };
 
 #define INVOICE_MAX_LABEL_LEN 128

wallet/wallet.c

@@ -1286,6 +1286,8 @@ static bool wallet_stmt2invoice(sqlite3_stmt *stmt, struct invoice *inv)
 	inv->label = tal_strndup(inv, sqlite3_column_blob(stmt, 4), sqlite3_column_bytes(stmt, 4));
 	inv->msatoshi = sqlite3_column_int64(stmt, 5);
 	inv->expiry_time = sqlite3_column_int64(stmt, 6);
+
+	list_head_init(&inv->invoice_waiters);
 	return true;
 }