lnrpc+lnd: adds required reserve in walletbalance rpc

lnrpc/lightning.proto

@@ -2567,6 +2567,9 @@ message WalletBalanceResponse {
     // other usage.
     int64 locked_balance = 5;
 
+    // The amount of reserve required.
+    int64 reserved_balance_anchor_chan = 6;
+
     // A mapping of each wallet account's name to its balance.
     map<string, WalletAccountBalance> account_balance = 4;
 }

lnrpc/lightning.swagger.json

@@ -6646,6 +6646,11 @@
           "format": "int64",
           "description": "The total amount of wallet UTXOs held in outputs that are locked for\nother usage."
         },
+        "reserved_balance_anchor_chan": {
+          "type": "string",
+          "format": "int64",
+          "description": "The amount of reserve required."
+        },
         "account_balance": {
           "type": "object",
           "additionalProperties": {

rpcserver.go

@@ -3136,6 +3136,17 @@ func (r *rpcServer) WalletBalance(ctx context.Context,
 		lockedBalance += utxoInfo.Value
 	}
 
+	// Get the current number of non-private anchor channels.
+	currentNumAnchorChans, err := r.server.cc.Wallet.CurrentNumAnchorChans()
+	if err != nil {
+		return nil, err
+	}
+
+	// Get the required reserve for the wallet.
+	requiredReserve := r.server.cc.Wallet.RequiredReserve(
+		uint32(currentNumAnchorChans),
+	)
+
 	rpcsLog.Debugf("[walletbalance] Total balance=%v (confirmed=%v, "+
 		"unconfirmed=%v)", totalBalance, confirmedBalance,
 		unconfirmedBalance)
@@ -3145,6 +3156,7 @@ func (r *rpcServer) WalletBalance(ctx context.Context,
 		ConfirmedBalance:          int64(confirmedBalance),
 		UnconfirmedBalance:        int64(unconfirmedBalance),
 		LockedBalance:             int64(lockedBalance),
+		ReservedBalanceAnchorChan: int64(requiredReserve),
 		AccountBalance:            rpcAccountBalances,
 	}, nil
 }