/// <summary>
///
/// </summary>
/// <param name="request"></param>
/// <param name="userId"></param>
/// <param name="lndClient"></param>
/// <returns></returns>
public object TryWithdrawal(string request, string userId, string ip, LndRpcClient lndClient)
{
// Check if payment request is ok
// Check if already paid
var decoded = lndClient.DecodePayment(request);
if (decoded == null)
{
return(new { Result = "Error decoding invoice." });
}
if (decoded.destination == null)
{
return(new { Result = "Error decoding invoice." });
}
using (var db = new ZapContext())
{
var user = db.Users
.Include(usr => usr.Funds)
.FirstOrDefault(u => u.AppId == userId);
if (user == null)
{
MailingService.Send(new UserEmailModel()
{
Destination = "*****@*****.**",
Body = " Withdraw from user which doesn't exist.",
Email = "",
Name = "zapread.com Monitoring",
Subject = "User withdraw error",
});
// Don't reveal information that user doesn't exist
return(new { Result = "Error processing request." });
}
if (user.Funds.Balance < Convert.ToDouble(decoded.num_satoshis))
{
return(new { Result = "Insufficient Funds. You have " + user.Funds.Balance.ToString("0.") + ", invoice is for " + decoded.num_satoshis + "." });
}
//insert transaction as pending
LNTransaction t = new LNTransaction()
{
IsSettled = false,
Memo = decoded.description ?? "Withdraw",
HashStr = decoded.payment_hash,
Amount = Convert.ToInt64(decoded.num_satoshis),
IsDeposit = false,
TimestampSettled = DateTime.UtcNow,
TimestampCreated = DateTime.UtcNow, //can't know
PaymentRequest = request,
FeePaid_Satoshi = 0,
NodePubKey = decoded.destination,
User = user,
};
db.LightningTransactions.Add(t);
db.SaveChanges();
SendPaymentResponse paymentresult;
//all (should be) ok - make the payment
if (WithdrawRequests.TryAdd(request, DateTime.UtcNow))
{
paymentresult = lndClient.PayInvoice(request);
}
else
{
//double request!
return(new { Result = "Please click only once. Payment already in processing." });
}
WithdrawRequests.TryRemove(request, out DateTime reqInitTime);
if (paymentresult == null)
{
t.ErrorMessage = "Error executing payment.";
db.SaveChanges();
return(new { Result = "Error executing payment." });
}
if (paymentresult.error != null && paymentresult.error != "")
{
t.ErrorMessage = "Error: " + paymentresult.error;
db.SaveChanges();
return(new { Result = "Error: " + paymentresult.error });
}
if (paymentresult.payment_error != null)
{
t.ErrorMessage = "Error: " + paymentresult.payment_error;
db.SaveChanges();
return(new { Result = "Error: " + paymentresult.payment_error });
}
// should this be done here? Is there an async/sync check that payment was sent successfully?
user.Funds.Balance -= Convert.ToDouble(decoded.num_satoshis);
db.SaveChanges();
//update transaction status
t.IsSettled = true;
t.FeePaid_Satoshi = (paymentresult.payment_route.total_fees == null ? 0 : Convert.ToInt64(paymentresult.payment_route.total_fees));
//db.LightningTransactions.Add(t);
db.SaveChanges();
return(new { Result = "success", Fees = 0 });
}
}
/// <summary>
///
/// </summary>
/// <param name="request"></param>
/// <param name="userAppId"></param>
/// <param name="lndClient"></param>
/// <param name="ip"></param>
/// <returns></returns>
public object TryWithdrawal(Models.LNTransaction request, string userAppId, string ip, LndRpcClient lndClient)
{
if (request == null)
{
return(new { success = false, message = "Internal error." });
}
if (lndClient == null)
{
return(HandleLndClientIsNull());
}
long FeePaid_Satoshi; // This is used later if the invoice succeeds.
User user = null;
SendPaymentResponse paymentresult = null;
using (var db = new ZapContext())
{
// Check when user has made last LN transaction
var lasttx = db.LightningTransactions
.Where(tx => tx.User.AppId == userAppId) // This user
.Where(tx => tx.Id != request.Id) // Not the one being processed now
.OrderByDescending(tx => tx.TimestampCreated) // Most recent
.AsNoTracking()
.FirstOrDefault();
if (lasttx != null && (DateTime.UtcNow - lasttx.TimestampCreated < TimeSpan.FromMinutes(5)))
{
return(new { success = false, message = "Please wait 5 minutes between Lightning transaction requests." });
}
// Check if user has sufficient balance
var userFunds = db.Users
.Where(u => u.AppId == userAppId)
.Select(usr => usr.Funds)
.FirstOrDefault();
if (userFunds == null)
{
return(HandleUserIsNull());
}
if (userFunds.IsWithdrawLocked)
{
return(new { success = false, message = "User withdraw is locked. Please contact an administrator." });
}
string responseStr = "";
//all (should be) ok - make the payment
if (WithdrawRequests.TryAdd(request.PaymentRequest, DateTime.UtcNow)) // This is to prevent flood attacks
{
// Check if user has sufficient balance
if (userFunds.Balance < Convert.ToDouble(request.Amount, CultureInfo.InvariantCulture))
{
return(new
{
success = false,
message = "Insufficient Funds. You have "
+ userFunds.Balance.ToString("0.", CultureInfo.CurrentCulture)
+ ", invoice is for " + request.Amount.ToString(CultureInfo.CurrentCulture)
+ "."
});
}
// Mark funds for withdraw as "in limbo" - will be resolved if verified as paid.
userFunds.LimboBalance += Convert.ToDouble(request.Amount, CultureInfo.InvariantCulture);
userFunds.Balance -= Convert.ToDouble(request.Amount, CultureInfo.InvariantCulture);
// Funds are checked for optimistic concurrency here. If the Balance has been updated,
// we shouldn't proceed with the withdraw, so we will abort it.
try
{
db.SaveChanges(); // Synchronous to ensure balance is locked.
}
catch (DbUpdateConcurrencyException)
{
// The balance has changed - don't do withdraw.
// This may trigger if the user also gets funds added - such as a tip.
// For now, we will fail the withdraw under any condition.
// In the future, we may consider ignoring changes increasing balance.
// Remove this request from the lock so the user can retry.
WithdrawRequests.TryRemove(request.PaymentRequest, out DateTime reqInitTimeReset);
return(new { success = false, message = "Failed. User balances changed during withdraw." });
}
// Get an update-able entity for the transaction from the DB
var t = db.LightningTransactions
.Where(tx => tx.Id == request.Id)
.Where(tx => tx.User.AppId == userAppId)
.FirstOrDefault();
if (t == null)
{
return(new { success = false, message = "Validated invoice not found in database." });
}
t.IsLimbo = true; // Mark the transaction as in limbo as we try to pay it
// Save the transaction state
try
{
db.SaveChanges();
}
catch (DbUpdateConcurrencyException)
{
// Remove this request from the lock so the user can retry.
WithdrawRequests.TryRemove(request.PaymentRequest, out DateTime reqInitTimeReset);
return(new { success = false, message = "Failed. Validated invoice modified during transaction." });
}
// Execute payment
try
{
paymentresult = lndClient.PayInvoice(request.PaymentRequest, out responseStr);
}
catch (RestException e)
{
user = db.Users
.Where(u => u.AppId == userAppId)
.FirstOrDefault();
t.IsError = true;
t.ErrorMessage = "REST exception executing payment";
// Save the transaction state
try
{
db.SaveChanges();
}
catch (DbUpdateConcurrencyException ex)
{
return(HandleClientRestException(userAppId, request.Id, "DB Cuncurrency exception: " + ex.Message + " REST Exception: " + responseStr, e));
}
// A RestException happens when there was an error with the LN node.
// At this point, the funds will remain in limbo until it is verified as paid by the
// periodic LNTransactionMonitor service.
return(HandleClientRestException(userAppId, request.Id, responseStr, e));
}
}
else
{
//double request!
return(new { success = false, message = "Please click only once. Payment already in processing." });
}
// If we are at this point, we are now checking the status of the payment.
if (paymentresult == null)
{
// Something went wrong. Check if the payment went through
var payments = lndClient.GetPayments(include_incomplete: true);
var pmt = payments.payments
.Where(p => p.payment_hash == request.HashStr)
.FirstOrDefault();
MailingService.Send(new UserEmailModel()
{
Destination = System.Configuration.ConfigurationManager.AppSettings["ExceptionReportEmail"],
Body = " Withdraw error: PayInvoice returned null result. \r\n hash: " + request.HashStr
+ "\r\n recovered by getpayments: " + (pmt != null ? "true" : "false") + "\r\n invoice: "
+ request + "\r\n user: "******"",
Name = "zapread.com Exception",
Subject = "User withdraw error 3",
});
if (pmt != null && pmt.status == "SUCCEEDED")
{
// Looks like the payment may have gone through.
// the payment went through process withdrawal
paymentresult = new SendPaymentResponse()
{
payment_route = new PaymentRoute()
{
total_fees = "0",
}
};
MailingService.Send(new UserEmailModel()
{
Destination = System.Configuration.ConfigurationManager.AppSettings["ExceptionReportEmail"],
Body = " Withdraw error: payment error "
+ "\r\n user: "******"\r\n username: "******"\r\n <br><br> response: " + responseStr,
Email = "",
Name = "zapread.com Exception",
Subject = "User withdraw possible error 6",
});
}
else
{
// Not recovered - it will be cued for checkup later. This could be caused by LND being "laggy"
// Reserve the user funds to prevent another withdraw
//user.Funds.LimboBalance += Convert.ToDouble(decoded.num_satoshis);
//user.Funds.Balance -= Convert.ToDouble(decoded.num_satoshis);
return(HandlePaymentRecoveryFailed(userAppId, request.Id));
}
}
// This shouldn't ever be hit - this response is obsolete.
// TODO watch for this error, and if not found by June 2020 - delete this code
if (paymentresult.error != null && paymentresult.error != "")
{
return(HandleLegacyPaymentRecoveryFailed(userAppId, request.Id, paymentresult, responseStr));
}
// The LND node returned an error
if (!String.IsNullOrEmpty(paymentresult.payment_error))//paymentresult.payment_error != null && paymentresult.payment_error != "")
{
// Funds will remain in Limbo until failure verified by LNTransactionMonitor
// TODO: verify trust in this method - funds could be returned to user here.
return(HandleLNPaymentError(userAppId, request.Id, paymentresult, responseStr));
}
FeePaid_Satoshi = (paymentresult.payment_route.total_fees == null ? 0 : Convert.ToInt64(paymentresult.payment_route.total_fees, CultureInfo.InvariantCulture));
// Unblock this request since it was successful
WithdrawRequests.TryRemove(request.PaymentRequest, out DateTime reqInitTime);
}
// We're going to start a new context as we are updating the Limbo Balance
using (var db = new ZapContext())
{
user = db.Users
.Where(u => u.AppId == userAppId)
.FirstOrDefault();
// Get an update-able entity for the transaction from the DB
var t = db.LightningTransactions
.Where(tx => tx.Id == request.Id)
.Where(tx => tx.User.AppId == userAppId)
.FirstOrDefault();
// We have already subtracted the balance from the user account, since the payment was
// successful, we leave it subtracted from the account and we remove the balance from limbo.
bool saveFailed;
int attempts = 0;
do
{
attempts++;
if (attempts > 50)
{
// We REALLY should never get to this point. If we're here, there is some strange
// deadlock, or the user is being abusive and the funds will stay in Limbo.
}
saveFailed = false;
user.Funds.LimboBalance -= Convert.ToDouble(request.Amount, CultureInfo.InvariantCulture);
//update transaction status in DB
// payment hash and preimage are B64 encoded. Here we convert to hex strings
var HexEncoder = new LightningLib.DataEncoders.HexEncoder(); // static method
string payment_hash_str = null; // default
string payment_preimage_str = null; // default
if (paymentresult != null && paymentresult.payment_hash != null)
{
payment_hash_str = HexEncoder.EncodeData(Convert.FromBase64String(paymentresult.payment_hash));
}
if (paymentresult != null && paymentresult.payment_preimage != null)
{
payment_preimage_str = HexEncoder.EncodeData(Convert.FromBase64String(paymentresult.payment_preimage));
}
t.IsSettled = true;
t.IsLimbo = false;
t.PaymentHash = payment_hash_str;
t.PaymentPreimage = payment_preimage_str; // Important: this is proof that we paid it
try
{
t.FeePaid_Satoshi = FeePaid_Satoshi;// (paymentresult.payment_route.total_fees == null ? 0 : Convert.ToInt64(paymentresult.payment_route.total_fees, CultureInfo.InvariantCulture));
}
catch
{
t.FeePaid_Satoshi = 0;
}
try
{
db.SaveChanges();
}
catch (System.Data.Entity.Infrastructure.DbUpdateConcurrencyException ex)
{
saveFailed = true;
foreach (var entry in ex.Entries)//.Single();
{
entry.Reload();
}
}
}while (saveFailed);
return(new { success = true, message = "success", Fees = 0, userBalance = user.Funds.Balance });
}
}