EstimateRouteFee

EstimateRouteFee allows callers to obtain a lower bound w.r.t how much it may cost to send an HTLC to the target end destination.

Source: routerrpc/router.proto

gRPC

rpc EstimateRouteFee (RouteFeeRequest) returns (RouteFeeResponse);

REST

HTTP Method	Path
POST	/v2/router/route/estimatefee

Code Samples

gRPC

Javascript

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

const GRPC_HOST = 'localhost:10009'
const MACAROON_PATH = 'LND_DIR/data/chain/bitcoin/regtest/admin.macaroon'
const TLS_PATH = 'LND_DIR/tls.cert'

const loaderOptions = {
  keepCase: true,
  longs: String,
  enums: String,
  defaults: true,
  oneofs: true,
};
const packageDefinition = protoLoader.loadSync(['lightning.proto', 'routerrpc/router.proto'], loaderOptions);
const routerrpc = grpc.loadPackageDefinition(packageDefinition).routerrpc;
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 routerrpc.Router(GRPC_HOST, creds);
let request = {
  dest: <bytes>,
  amt_sat: <int64>,
};
client.estimateRouteFee(request, function(err, response) {
  console.log(response);
});
// Console output:
//  {
//    "routing_fee_msat": <int64>,
//    "time_lock_delay": <int64>,
//  }

Python

import codecs, grpc, os
# Generate the following 2 modules by compiling the routerrpc/router.proto with the grpcio-tools.
# See https://github.com/lightningnetwork/lnd/blob/master/docs/grpc/python.md for instructions.
import router_pb2 as routerrpc, router_pb2_grpc as routerstub

GRPC_HOST = 'localhost:10009'
MACAROON_PATH = 'LND_DIR/data/chain/bitcoin/regtest/admin.macaroon'
TLS_PATH = 'LND_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 = routerstub.RouterStub(channel)
request = routerrpc.RouteFeeRequest(
  dest=<bytes>,
  amt_sat=<int64>,
)
response = stub.EstimateRouteFee(request)
print(response)
# {
#    "routing_fee_msat": <int64>,
#    "time_lock_delay": <int64>,
# }

REST

Javascript

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

const REST_HOST = 'localhost:8080'
const MACAROON_PATH = 'LND_DIR/data/chain/bitcoin/regtest/admin.macaroon'

let requestBody = {
  dest: <string>, // <bytes> (base64 encoded)
  amt_sat: <string>, // <int64> 
};
let options = {
  url: `https://${REST_HOST}/v2/router/route/estimatefee`,
  // Work-around for self-signed certificates.
  rejectUnauthorized: false,
  json: true,
  headers: {
    'Grpc-Metadata-macaroon': fs.readFileSync(MACAROON_PATH).toString('hex'),
  },
  form: JSON.stringify(requestBody),
}
request.post(options, function(error, response, body) {
  console.log(body);
});
// Console output:
//  {
//    "routing_fee_msat": <string>, // <int64> 
//    "time_lock_delay": <string>, // <int64> 
//  }

Python

import base64, codecs, json, requests

REST_HOST = 'localhost:8080'
MACAROON_PATH = 'LND_DIR/data/chain/bitcoin/regtest/admin.macaroon'
TLS_PATH = 'LND_DIR/tls.cert'

url = f'https://{REST_HOST}/v2/router/route/estimatefee'
macaroon = codecs.encode(open(MACAROON_PATH, 'rb').read(), 'hex')
headers = {'Grpc-Metadata-macaroon': macaroon}
data = {
  'dest': base64.b64encode(<bytes>),
  'amt_sat': <int64>,
}
r = requests.post(url, headers=headers, data=json.dumps(data), verify=TLS_PATH)
print(r.json())
# {
#    "routing_fee_msat": <int64>,
#    "time_lock_delay": <int64>,
# }

Shell

# There is no CLI command for this RPC

Messages

routerrpc.RouteFeeRequest

Source: routerrpc/router.proto

Field	gRPC Type	REST Type	REST Placement
dest The destination once wishes to obtain a routing fee quote to.	bytes	string	body
amt_sat The amount one wishes to send to the target destination.	int64	string	body

routerrpc.RouteFeeResponse

Source: routerrpc/router.proto

Field	gRPC Type	REST Type
routing_fee_msat A lower bound of the estimated fee to the target destination within the network, expressed in milli-satoshis.	int64	string
time_lock_delay An estimate of the worst case time delay that can occur. Note that callers will still need to factor in the final CLTV delta of the last hop into this value.	int64	string