BIP79 Support

[Kukks]

This PR adds support for BIP79 Payjoin sender support.
When a BIP21 is pasted into the address field and the bpu parameter is specified, it will attempt to send the signed transaction to the specified endpoint. If the response is successful, you should have updated, partially signed transaction with more inputs which is then verified, signed and broadcasted.

This is a very rough implementation as my knowledge of the wasabi codebase is limited.

ToDo (Incomplete)

• Make sure CustomChangeAddress text box isn't visible when payjoin is used - Logical Operators on Binding AvaloniaUI/Avalonia#3666

[MaxHillebrand]

This is very exciting @Kukks, thanks for this!
Do you by now have the testnet payjoin btcpay server up and running? Can you please link to it here.

[Kukks]

https://demo.payjoin.kukks.org

…

On Sun, 15 Mar 2020, 10:03 Max Hillebrand, ***@***.***> wrote: ***@***.**** commented on this pull request. This is very exciting @Kukks <https://github.com/Kukks>, thanks for this! Do you by now have the testnet payjoin btcpay server up and running? Can you please link to it here. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#3256 (review)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAN357T4NTTR25OCOMFPWA3RHSKUXANCNFSM4LIRG3CA> .

[nopara73]

Something is off with CI here. For some strange reason only Linux runs. Other PRs are working properly.

[MaxHillebrand]

Tested on Qubes 4, Debian 10

At first, I pasted the url, and it showed the address, not the endpoint. When I pressed send, I got these errors.

2020-03-26 17:28:11 INFO	TransactionFactory (104)	Calculating dynamic transaction fee...
2020-03-26 17:28:11 INFO	TransactionFactory (171)	Fee: 141 Satoshi.
2020-03-26 17:28:11 INFO	TransactionFactory (174)	Estimated tx size: 141 vBytes.
2020-03-26 17:28:11 INFO	TransactionFactory (215)	Signing transaction...
2020-03-26 17:28:13 ERROR	SendControlViewModel (415)	System.AggregateException: One or more errors occurred. (Object reference not set to an instance of an object.)
 ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at WalletWasabi.TorSocks5.TorHttpClient.SendAsync(HttpRequestMessage request, CancellationToken cancel) in /home/user/WalletWasabi/WalletWasabi/TorSocks5/TorHttpClient.cs:line 174
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at System.Threading.Tasks.Task`1.get_Result()
   at WalletWasabi.Blockchain.Transactions.TransactionFactory.BuildTransaction(PaymentIntent payments, Func`1 feeRateFetcher, IEnumerable`1 allowedInputs, Func`1 lockTimeSelector, ITorHttpClient httpClient, String uri) in /home/user/WalletWasabi/WalletWasabi/Blockchain/Transactions/TransactionFactory.cs:line 236
   at WalletWasabi.Wallets.Wallet.BuildTransaction(String password, PaymentIntent payments, FeeStrategy feeStrategy, Boolean allowUnconfirmed, IEnumerable`1 allowedInputs, String bip79) in /home/user/WalletWasabi/WalletWasabi/Wallets/Wallet.cs:line 296
   at WalletWasabi.Gui.Controls.WalletExplorer.SendControlViewModel.<>c__DisplayClass45_0.<.ctor>b__42() in /home/user/WalletWasabi/WalletWasabi.Gui/Controls/WalletExplorer/SendControlViewModel.cs:line 398
   at System.Threading.Tasks.Task`1.InnerInvoke()
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location where exception was thrown ---
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
--- End of stack trace from previous location where exception was thrown ---
   at WalletWasabi.Gui.Controls.WalletExplorer.SendControlViewModel.<.ctor>b__45_26() in /home/user/WalletWasabi/WalletWasabi.Gui/Controls/WalletExplorer/SendControlViewModel.cs:line 398

Then, I pasted the same url again, and it showed the endpoint, and the transaction was successfully broadcasted, however, it was not a payjoin also not on the second attempt

2020-03-26 17:28:52 INFO	TransactionFactory (104)	Calculating dynamic transaction fee...
2020-03-26 17:28:52 INFO	TransactionFactory (171)	Fee: 141 Satoshi.
2020-03-26 17:28:52 INFO	TransactionFactory (174)	Estimated tx size: 141 vBytes.
2020-03-26 17:28:52 INFO	TransactionFactory (215)	Signing transaction...
2020-03-26 17:28:53 INFO	TransactionFactory (337)	Transaction is successfully built: e8d31e78f95d78cd190fdef84b08ab8380ff5f0e97f0047d259487b07f6e4b4c.
2020-03-26 17:28:53 INFO	TransactionBroadcaster (46)	Trying to broadcast transaction with random node (::ffff:198.251.83.19):e8d31e78f95d78cd190fdef84b08ab8380ff5f0e97f0047d259487b07f6e4b4c.
2020-03-26 17:28:56 INFO	P2pBehavior (113)	Successfully served transaction to node ([::ffff:198.251.83.19]:18333): e8d31e78f95d78cd190fdef84b08ab8380ff5f0e97f0047d259487b07f6e4b4c.
2020-03-26 17:28:56 INFO	TransactionBroadcaster (69)	Disconnected node: ::ffff:198.251.83.19. Successfully broadcasted transaction: e8d31e78f95d78cd190fdef84b08ab8380ff5f0e97f0047d259487b07f6e4b4c.
2020-03-26 17:28:58 INFO	Global (587)	Transaction Notification (Information): Sent - 0.00030377 BTC - e8d31e78f95d78cd190fdef84b08ab8380ff5f0e97f0047d259487b07f6e4b4c
2020-03-26 17:29:00 INFO	TransactionBroadcaster (82)	Transaction is successfully propagated: e8d31e78f95d78cd190fdef84b08ab8380ff5f0e97f0047d259487b07f6e4b4c.

[Kukks]

Superseded by #3528