DB: Store the remote channel announcement signatures into DB

1. Add the fields of remote channel announcement signatures into TABLE channels
2. Add the related function

wallet/db.c

@@ -382,6 +382,9 @@ static struct migration dbmigrations[] = {
 	{ "ALTER TABLE channels ADD remote_upfront_shutdown_script BLOB;", NULL },
 	/* PR #2524: Add failcode into forward_payment */
 	{ "ALTER TABLE forwarded_payments ADD failcode INTEGER;", NULL },
+	/* remote signatures for channel announcement */
+	{ "ALTER TABLE channels ADD remote_ann_node_sig BLOB;", NULL },
+	{ "ALTER TABLE channels ADD remote_ann_bitcoin_sig BLOB;", NULL },
 };
 
 /* Leak tracking. */

wallet/wallet.c

@@ -595,6 +595,50 @@ wallet_htlc_sigs_load(const tal_t *ctx, struct wallet *w, u64 channelid)
 	return htlc_sigs;
 }
 
+bool wallet_remote_ann_sigs_load(const tal_t *ctx, struct wallet *w, u64 id,
+				 secp256k1_ecdsa_signature **remote_ann_node_sig,
+				 secp256k1_ecdsa_signature **remote_ann_bitcoin_sig)
+{
+	sqlite3_stmt *stmt;
+	int res;
+	stmt = db_select_prepare(w->db,
+				 "remote_ann_node_sig, remote_ann_bitcoin_sig"
+				 " FROM channels WHERE id = ?");
+	sqlite3_bind_int64(stmt, 1, id);
+
+	res = sqlite3_step(stmt);
+
+	/* This must succeed, since we know the channel exists */
+	assert(res == SQLITE_ROW);
+
+	/* if only one sig exists, forget the sig and hope peer send new ones*/
+	if(sqlite3_column_type(stmt, 0) == SQLITE_NULL ||
+			sqlite3_column_type(stmt, 1) == SQLITE_NULL) {
+		*remote_ann_node_sig = *remote_ann_bitcoin_sig = NULL;
+		db_stmt_done(stmt);
+		return true;
+	}
+
+	/* the case left over is both sigs exist */
+	*remote_ann_node_sig = tal(ctx, secp256k1_ecdsa_signature);
+	*remote_ann_bitcoin_sig = tal(ctx, secp256k1_ecdsa_signature);
+
+	if (!sqlite3_column_signature(stmt, 0, *remote_ann_node_sig))
+		goto fail;
+
+	if (!sqlite3_column_signature(stmt, 1, *remote_ann_bitcoin_sig))
+		goto fail;
+
+	db_stmt_done(stmt);
+	return true;
+
+fail:
+	*remote_ann_node_sig = tal_free(*remote_ann_node_sig);
+	*remote_ann_bitcoin_sig = tal_free(*remote_ann_bitcoin_sig);
+	db_stmt_done(stmt);
+	return false;
+}
+
 /**
  * wallet_stmt2channel - Helper to populate a wallet_channel from a sqlite3_stmt
  */
@@ -951,6 +995,24 @@ u64 wallet_get_channel_dbid(struct wallet *wallet)
 	return ++wallet->max_channel_dbid;
 }
 
+/* When we receive the remote announcement message, we will also call this function */
+void wallet_announcement_save(struct wallet *w, u64 id,
+			      secp256k1_ecdsa_signature *remote_ann_node_sig,
+			      secp256k1_ecdsa_signature *remote_ann_bitcoin_sig)
+{
+	sqlite3_stmt *stmt;
+
+	stmt = db_prepare(w->db, "UPDATE channels SET"
+			  "  remote_ann_node_sig=?,"
+			  "  remote_ann_bitcoin_sig=?"
+			  " WHERE id=?");
+
+	sqlite3_bind_signature(stmt, 1, remote_ann_node_sig);
+	sqlite3_bind_signature(stmt, 2, remote_ann_bitcoin_sig);
+	sqlite3_bind_int64(stmt, 3, id);
+	db_exec_prepared(w->db, stmt);
+}
+
 void wallet_channel_save(struct wallet *w, struct channel *chan)
 {
 	sqlite3_stmt *stmt;

wallet/wallet.h

@@ -555,6 +555,21 @@ bool wallet_htlcs_load_for_channel(struct wallet *wallet,
 				   struct htlc_in_map *htlcs_in,
 				   struct htlc_out_map *htlcs_out);
 
+/**
+ * wallet_announcement_save - Save remote announcement information with channel.
+ *
+ * @wallet: wallet to load from
+ * @id: channel database id
+ * @remote_ann_node_sig: location to load remote_ann_node_sig to
+ * @remote_ann_bitcoin_sig: location to load remote_ann_bitcoin_sig to
+ *
+ * This function is only used to save REMOTE announcement information into DB
+ * when the channel has set the announce_channel bit and don't send the shutdown
+ * message(BOLT#7).
+ */
+void wallet_announcement_save(struct wallet *wallet, u64 id,
+			      secp256k1_ecdsa_signature *remote_ann_node_sig,
+			      secp256k1_ecdsa_signature *remote_ann_bitcoin_sig);
 
 /* /!\ This is a DB ENUM, please do not change the numbering of any
  * already defined elements (adding is ok) /!\ */
@@ -1052,4 +1067,17 @@ struct amount_msat wallet_total_forward_fees(struct wallet *w);
  */
 const struct forwarding *wallet_forwarded_payments_get(struct wallet *w,
 						       const tal_t *ctx);
+
+/**
+ * Load remote_ann_node_sig and remote_ann_bitcoin_sig
+ *
+ * @ctx: allocation context for the return value
+ * @w: wallet containing the channel
+ * @id: channel database id
+ * @remote_ann_node_sig: location to load remote_ann_node_sig to
+ * @remote_ann_bitcoin_sig: location to load remote_ann_bitcoin_sig to
+ */
+bool wallet_remote_ann_sigs_load(const tal_t *ctx, struct wallet *w, u64 id,
+				 secp256k1_ecdsa_signature **remote_ann_node_sig,
+				 secp256k1_ecdsa_signature **remote_ann_bitcoin_sig);
 #endif /* LIGHTNING_WALLET_WALLET_H */