wallet: recoverchannel RPC only stubs a channel if the id is vacant i…

…n the DB as well. Closed channels are not loaded inside the peer struct, hence find_channel_by_id fails when the id is occupied by a closed channel. So we need to create a function to directly check if the ID is occupied or not.

lightningd/opening_control.c

@@ -1480,13 +1480,10 @@ static struct channel *stub_chan(struct command *cmd,
 				    144);
 
 	/* If the channel is already stored, return NULL. */
-	peer = peer_by_id(cmd->ld, &nodeid);
-	if (peer) {
-		if (find_channel_by_id(peer, &cid)) {
-			log_debug(cmd->ld->log, "channel %s already exists!",
-				  fmt_channel_id(tmpctx, &cid));
-			return NULL;
-		}
+	if (channel_exists_by_id(cmd->ld->wallet, id)) {
+		log_debug(cmd->ld->log, "channel %s already exists!",
+				fmt_channel_id(tmpctx, &cid));
+		return NULL;
 	} else {
 		struct wireaddr_internal wint;
 

wallet/wallet.c

@@ -2586,6 +2586,26 @@ static void wallet_peer_save(struct wallet *w, struct peer *peer)
 	}
 }
 
+bool channel_exists_by_id(struct wallet *w, u64 dbid) {
+	struct db_stmt *stmt;
+	stmt = db_prepare_v2(w->db, SQL("SELECT *"
+					" FROM channels"
+					" WHERE id = ?"));
+
+	db_bind_u64(stmt, dbid);
+	db_query_prepared(stmt);
+
+	/* If we found a result it means channel exists at that place. */
+	if (db_step(stmt)) {
+		db_col_ignore(stmt, "*");
+		tal_free(stmt);
+		return true;
+	}
+
+	tal_free(stmt);
+	return false;
+}
+
 void wallet_channel_insert(struct wallet *w, struct channel *chan)
 {
 	struct db_stmt *stmt;

wallet/wallet.h

@@ -607,6 +607,16 @@ void wallet_htlcsigs_confirm_inflight(struct wallet *w, struct channel *chan,
  */
 void wallet_channel_save(struct wallet *w, struct channel *chan);
 
+/**
+ * wallet_channels_by_dbid -- Check if an ID is preoccupied inside the `channels` table
+ *
+ * @wallet: the wallet
+ * @dbid: the ID at which we want to check the value.
+ *
+ * Returns `true` if it is occupied, false otherwise.
+*/
+bool channel_exists_by_id(struct wallet *w, u64 dbid);
+
 /**
  * wallet_channel_insert -- Insert the initial channel into the database
  *