LoopOutQuote

LoopOutQuote returns a quote for a loop out swap with the provided parameters.

Source: looprpc/client.proto

gRPC

rpc LoopOutQuote (QuoteRequest) returns (OutQuoteResponse);

REST

HTTP Method	Path
GET	/v1/loop/out/quote/{amt}

Code Samples

gRPC

Javascript

const fs = require('fs');
const grpc = require('@grpc/grpc-js');
const protoLoader = require('@grpc/proto-loader');

const GRPC_HOST = 'localhost:11010'
const MACAROON_PATH = 'LOOP_DIR/regtest/loop.macaroon'
const TLS_PATH = 'LOOP_DIR/tls.cert'

const loaderOptions = {
  keepCase: true,
  longs: String,
  enums: String,
  defaults: true,
  oneofs: true,
};
const packageDefinition = protoLoader.loadSync('looprpc/client.proto', loaderOptions);
const looprpc = grpc.loadPackageDefinition(packageDefinition).looprpc;
process.env.GRPC_SSL_CIPHER_SUITES = 'HIGH+ECDSA';
const tlsCert = fs.readFileSync(TLS_PATH);
const sslCreds = grpc.credentials.createSsl(tlsCert);
const macaroon = fs.readFileSync(MACAROON_PATH).toString('hex');
const macaroonCreds = grpc.credentials.createFromMetadataGenerator(function(args, callback) {
  let metadata = new grpc.Metadata();
  metadata.add('macaroon', macaroon);
  callback(null, metadata);
});
let creds = grpc.credentials.combineChannelCredentials(sslCreds, macaroonCreds);
let client = new looprpc.SwapClient(GRPC_HOST, creds);
let request = {
  amt: <int64>,
  conf_target: <int32>,
  external_htlc: <bool>,
  swap_publication_deadline: <uint64>,
  loop_in_last_hop: <bytes>,
  loop_in_route_hints: <RouteHint>,
  private: <bool>,
};
client.loopOutQuote(request, function(err, response) {
  console.log(response);
});
// Console output:
//  {
//    "swap_fee_sat": <int64>,
//    "prepay_amt_sat": <int64>,
//    "htlc_sweep_fee_sat": <int64>,
//    "swap_payment_dest": <bytes>,
//    "cltv_delta": <int32>,
//    "conf_target": <int32>,
//  }

Python

import codecs, grpc, os
# Generate the following 2 modules by compiling the looprpc/client.proto with the grpcio-tools.
# See https://github.com/lightningnetwork/lnd/blob/master/docs/grpc/python.md for instructions.
import client_pb2 as looprpc, client_pb2_grpc as clientstub

GRPC_HOST = 'localhost:11010'
MACAROON_PATH = 'LOOP_DIR/regtest/loop.macaroon'
TLS_PATH = 'LOOP_DIR/tls.cert'

# create macaroon credentials
macaroon = codecs.encode(open(MACAROON_PATH, 'rb').read(), 'hex')
def metadata_callback(context, callback):
  callback([('macaroon', macaroon)], None)
auth_creds = grpc.metadata_call_credentials(metadata_callback)
# create SSL credentials
os.environ['GRPC_SSL_CIPHER_SUITES'] = 'HIGH+ECDSA'
cert = open(TLS_PATH, 'rb').read()
ssl_creds = grpc.ssl_channel_credentials(cert)
# combine macaroon and SSL credentials
combined_creds = grpc.composite_channel_credentials(ssl_creds, auth_creds)
# make the request
channel = grpc.secure_channel(GRPC_HOST, combined_creds)
stub = clientstub.SwapClientStub(channel)
request = looprpc.QuoteRequest(
  amt=<int64>,
  conf_target=<int32>,
  external_htlc=<bool>,
  swap_publication_deadline=<uint64>,
  loop_in_last_hop=<bytes>,
  loop_in_route_hints=<RouteHint>,
  private=<bool>,
)
response = stub.LoopOutQuote(request)
print(response)
# {
#    "swap_fee_sat": <int64>,
#    "prepay_amt_sat": <int64>,
#    "htlc_sweep_fee_sat": <int64>,
#    "swap_payment_dest": <bytes>,
#    "cltv_delta": <int32>,
#    "conf_target": <int32>,
# }

REST

Javascript

const fs = require('fs');
const request = require('request');

const REST_HOST = 'localhost:8081'
const MACAROON_PATH = 'LOOP_DIR/regtest/loop.macaroon'

let options = {
  url: `https://${REST_HOST}/v1/loop/out/quote/{amt}`,
  // Work-around for self-signed certificates.
  rejectUnauthorized: false,
  json: true,
  headers: {
    'Grpc-Metadata-macaroon': fs.readFileSync(MACAROON_PATH).toString('hex'),
  },
}
request.get(options, function(error, response, body) {
  console.log(body);
});
// Console output:
//  {
//    "swap_fee_sat": <string>, // <int64> 
//    "prepay_amt_sat": <string>, // <int64> 
//    "htlc_sweep_fee_sat": <string>, // <int64> 
//    "swap_payment_dest": <string>, // <bytes> 
//    "cltv_delta": <integer>, // <int32> 
//    "conf_target": <integer>, // <int32> 
//  }

Python

import base64, codecs, json, requests

REST_HOST = 'localhost:8081'
MACAROON_PATH = 'LOOP_DIR/regtest/loop.macaroon'
TLS_PATH = 'LOOP_DIR/tls.cert'

url = f'https://{REST_HOST}/v1/loop/out/quote/{amt}'
macaroon = codecs.encode(open(MACAROON_PATH, 'rb').read(), 'hex')
headers = {'Grpc-Metadata-macaroon': macaroon}
r = requests.get(url, headers=headers, verify=TLS_PATH)
print(r.json())
# {
#    "swap_fee_sat": <int64>,
#    "prepay_amt_sat": <int64>,
#    "htlc_sweep_fee_sat": <int64>,
#    "swap_payment_dest": <bytes>,
#    "cltv_delta": <int32>,
#    "conf_target": <int32>,
# }

Shell

$ loop quote --help

NAME:
   loop quote - get a quote for the cost of a swap

USAGE:
   loop quote command [command options] [arguments...]

COMMANDS:
   in   get a quote for the cost of a loop in swap
   out  get a quote for the cost of a loop out swap

OPTIONS:
   --help, -h  show help
   

Messages

looprpc.QuoteRequest

Source: looprpc/client.proto

Field	gRPC Type	REST Type	REST Placement
amt The amount to swap in satoshis.	int64	string	path
conf_target The confirmation target that should be used either for the sweep of the on-chain HTLC broadcast by the swap server in the case of a Loop Out, or for the confirmation of the on-chain HTLC broadcast by the swap client in the case of a Loop In.	int32	integer	query
external_htlc If external_htlc is true, we expect the htlc to be published by an external actor.	bool	boolean	query
swap_publication_deadline The latest time (in unix seconds) we allow the server to wait before publishing the HTLC on chain. Setting this to a larger value will give the server the opportunity to batch multiple swaps together, and wait for low-fee periods before publishing the HTLC, potentially resulting in a lower total swap fee. This only has an effect on loop out quotes.	uint64	string	query
loop_in_last_hop Optionally the client can specify the last hop pubkey when requesting a loop-in quote. This is useful to get better off-chain routing fee from the server.	bytes	string	query
loop_in_route_hints Optional route hints to reach the destination through private channels.	RouteHint[]	object	unknown
private Private indicates whether the destination node should be considered private. In which case, loop will generate hophints to assist with probing and payment.	bool	boolean	query

looprpc.OutQuoteResponse

Source: looprpc/client.proto

Field	gRPC Type	REST Type
swap_fee_sat The fee that the swap server is charging for the swap.	int64	string
prepay_amt_sat The part of the swap fee that is requested as a prepayment.	int64	string
htlc_sweep_fee_sat An estimate of the on-chain fee that needs to be paid to sweep the HTLC for a loop out.	int64	string
swap_payment_dest The node pubkey where the swap payment needs to be paid to. This can be used to test connectivity before initiating the swap.	bytes	string
cltv_delta On-chain cltv expiry delta	int32	integer
conf_target The confirmation target to be used for the sweep of the on-chain HTLC.	int32	integer