SweepHtlc

SweepHtlc spends a swap HTLC output via the preimage (success) path using the swap's known preimage or an optionally supplied one.

Source: looprpc/client.proto

gRPC

rpc SweepHtlc (SweepHtlcRequest) returns (SweepHtlcResponse);

REST

HTTP Method	Path
POST	/v1/loop/out/sweephtlc

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 = {
  dest_address: <string>,
  sat_per_vbyte: <uint32>,
  outpoint: <string>,
  preimage: <bytes>,
  publish: <bool>,
  htlc_address: <string>,
};
client.sweepHtlc(request, function(err, response) {
  console.log(response);
});
// Console output:
//  {
//    "sweep_tx": <bytes>,
//    "fee_sats": <uint64>,
//    "not_requested": <PublishNotRequested>,
//    "published": <PublishSucceeded>,
//    "failed": <PublishFailed>,
//  }

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.SweepHtlcRequest(
  dest_address=<string>,
  sat_per_vbyte=<uint32>,
  outpoint=<string>,
  preimage=<bytes>,
  publish=<bool>,
  htlc_address=<string>,
)
response = stub.SweepHtlc(request)
print(response)
# {
#    "sweep_tx": <bytes>,
#    "fee_sats": <uint64>,
#    "not_requested": <PublishNotRequested>,
#    "published": <PublishSucceeded>,
#    "failed": <PublishFailed>,
# }

REST

Javascript

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

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

let requestBody = {
  dest_address: <string>, // <string> 
  sat_per_vbyte: <integer>, // <uint32> 
  outpoint: <string>, // <string> 
  preimage: <string>, // <bytes> (base64 encoded)
  publish: <boolean>, // <bool> 
  htlc_address: <string>, // <string> 
};
let options = {
  url: `https://${REST_HOST}/v1/loop/out/sweephtlc`,
  // 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:
//  {
//    "sweep_tx": <string>, // <bytes> 
//    "fee_sats": <string>, // <uint64> 
//    "not_requested": <object>, // <PublishNotRequested> 
//    "published": <object>, // <PublishSucceeded> 
//    "failed": <object>, // <PublishFailed> 
//  }

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/sweephtlc'
macaroon = codecs.encode(open(MACAROON_PATH, 'rb').read(), 'hex')
headers = {'Grpc-Metadata-macaroon': macaroon}
data = {
  'dest_address': <string>,
  'sat_per_vbyte': <uint32>,
  'outpoint': <string>,
  'preimage': base64.b64encode(<bytes>),
  'publish': <bool>,
  'htlc_address': <string>,
}
r = requests.post(url, headers=headers, data=json.dumps(data), verify=TLS_PATH)
print(r.json())
# {
#    "sweep_tx": <bytes>,
#    "fee_sats": <uint64>,
#    "not_requested": <PublishNotRequested>,
#    "published": <PublishSucceeded>,
#    "failed": <PublishFailed>,
# }

Shell

# There is no CLI command for this RPC

Messages

looprpc.SweepHtlcRequest

Source: looprpc/client.proto

Field	gRPC Type	REST Type	REST Placement
dest_address Optional override for the sweep destination; defaults to a new address derived from the connected lnd wallet.	string	string	body
sat_per_vbyte Fee rate used for the sweep transaction in sat/vByte.	uint32	integer	body
outpoint HTLC outpoint to sweep, formatted as "txid:vout".	string	string	body
preimage Optional override for the stored swap preimage.	bytes	string	body
publish If true, publish the sweep transaction immediately.	bool	boolean	body
htlc_address The HTLC address whose output is being swept; used to derive the expected pkScript.	string	string	body

looprpc.SweepHtlcResponse

Source: looprpc/client.proto

Field	gRPC Type	REST Type
sweep_tx Raw sweep transaction bytes.	bytes	string
fee_sats Miner fee paid by the sweep transaction.	uint64	string
not_requested	PublishNotRequested	object
published	PublishSucceeded	object
failed	PublishFailed	object

Nested Messages

looprpc.PublishFailed

Field	gRPC Type	REST Type
error	string	string

looprpc.PublishNotRequested

note

This response has no parameters.

looprpc.PublishSucceeded

note

This response has no parameters.