feat(rpc): deposit & withdraw calls using lnd

This adds new rpc calls that allow to get new deposit addresses and
withdraw coins via xud. Currently these calls only support lnd.

Closes #1062.

lib/cli/commands/deposit.ts

@@ -0,0 +1,20 @@
+import { Arguments } from 'yargs';
+import { DepositRequest } from '../../proto/xudrpc_pb';
+import { callback, loadXudClient } from '../command';
+
+export const command = 'deposit <currency>';
+
+export const describe = 'gets an address to deposit funds to xud';
+
+export const builder = {
+  currency: {
+    description: 'the ticker symbol of the currency to deposit.',
+    type: 'string',
+  },
+};
+
+export const handler = (argv: Arguments<any>) => {
+  const request = new DepositRequest();
+  request.setCurrency(argv.currency);
+  loadXudClient(argv).deposit(request, callback(argv));
+};

lib/cli/commands/withdraw.ts

@@ -0,0 +1,44 @@
+import { Arguments } from 'yargs';
+import { WithdrawRequest } from '../../proto/xudrpc_pb';
+import { callback, loadXudClient } from '../command';
+
+export const command = 'withdraw <amount> <currency> <destination> [fee]';
+
+export const describe = 'withdraws on-chain funds from xud';
+
+export const builder = {
+  amount: {
+    description: 'the amount to withdraw',
+    type: 'number',
+  },
+  currency: {
+    description: 'the ticker symbol of the currency to withdraw.',
+    type: 'string',
+  },
+  destination: {
+    description: 'the address to send withdrawn funds to',
+    type: 'string',
+  },
+  fee: {
+    description: 'the fee in satoshis (or equivalent) per byte',
+    type: 'number',
+  },
+  all: {
+    description: 'whether to withdraw all available funds for the specified currency',
+    type: 'boolean',
+  },
+};
+
+export const handler = (argv: Arguments<any>) => {
+  const request = new WithdrawRequest();
+  request.setCurrency(argv.currency);
+  if (argv.all) {
+    request.setAll(argv.all);
+  } else {
+    request.setAmount(argv.amount);
+  }
+  request.setDestination(argv.destination);
+  request.setFee(argv.fee);
+
+  loadXudClient(argv).withdraw(request, callback(argv));
+};

lib/grpc/GrpcService.ts

@@ -309,7 +309,39 @@ class GrpcService {
     try {
       const { nodeUri } = call.request.toObject();
       await this.service.connect({ nodeUri, retryConnecting: false });
-      const response = new xudrpc.ConnectResponse();
+      const response = new xudrpc.WithdrawResponse();
+      callback(null, response);
+    } catch (err) {
+      callback(getGrpcError(err), null);
+    }
+  }
+
+  /**
+   * See [[Service.deposit]]
+   */
+  public deposit: grpc.handleUnaryCall<xudrpc.DepositRequest, xudrpc.DepositResponse> = async (call, callback) => {
+    if (!this.isReady(this.service, callback)) {
+      return;
+    }
+    try {
+      await this.service.deposit(call.request.toObject());
+      const response = new xudrpc.DepositResponse();
+      callback(null, response);
+    } catch (err) {
+      callback(getGrpcError(err), null);
+    }
+  }
+
+  /**
+   * See [[Service.withdraw]]
+   */
+  public withdraw: grpc.handleUnaryCall<xudrpc.WithdrawRequest, xudrpc.WithdrawResponse> = async (call, callback) => {
+    if (!this.isReady(this.service, callback)) {
+      return;
+    }
+    try {
+      await this.service.withdraw(call.request.toObject());
+      const response = new xudrpc.WithdrawResponse();
       callback(null, response);
     } catch (err) {
       callback(getGrpcError(err), null);

lib/lndclient/LndClient.ts

@@ -519,6 +519,26 @@ class LndClient extends SwapClient {
     return this.unaryCall<lndrpc.ClosedChannelsRequest, lndrpc.ClosedChannelsResponse>('closedChannels', new lndrpc.ClosedChannelsRequest());
   }
 
+  public withdraw = async ({ amount, destination, all = false, fee }: {
+    amount: number,
+    destination: string,
+    all?: boolean,
+    fee?: number,
+  }) => {
+    const request = new lndrpc.SendCoinsRequest();
+    request.setAddr(destination);
+    if (fee) {
+      request.setSatPerByte(fee);
+    }
+    if (all) {
+      request.setSendAll(all);
+    } else {
+      request.setAmount(amount);
+    }
+    const withdrawResponse = await this.unaryCall<lndrpc.SendCoinsRequest, lndrpc.SendCoinsResponse>('sendCoins', request);
+    return withdrawResponse.getTxid();
+  }
+
   public sendSmallestAmount = async (rHash: string, destination: string): Promise<string> => {
     const request = this.buildSendRequest({
       rHash,
@@ -633,10 +653,11 @@ class LndClient extends SwapClient {
   /**
    * Gets a new address for the internal lnd wallet.
    */
-  public newAddress = (addressType: lndrpc.AddressType): Promise<lndrpc.NewAddressResponse> => {
+  public newAddress = async (addressType = lndrpc.AddressType.WITNESS_PUBKEY_HASH) => {
     const request = new lndrpc.NewAddressRequest();
     request.setType(addressType);
-    return this.unaryCall<lndrpc.NewAddressRequest, lndrpc.NewAddressResponse>('newAddress', request);
+    const newAddressResponse = await this.unaryCall<lndrpc.NewAddressRequest, lndrpc.NewAddressResponse>('newAddress', request);
+    return newAddressResponse.getAddress();
   }
 
   /**