Pretix Ethereum Payment Provider

Important disclaimers

!! Smart contract wallet payments are NOT supported (except Safe) and users will be told so (and be unable to pay) when they connect with one. A rare edge case exists with counterfactual wallets that will prevent the plugin from detecting if the connected wallet is a smart contract - if a user manages to pay this way, their payment will not confirm automatically (note: an organizer can still manually confirm payments in this case)

!! This plugin is no longer actively being worked on. PRs to finish smart contract wallet support are welcome (further details below). As of early 2024, The Devcon team is working with third party payment providers to improve payment UX and add smart contract wallet support, and may publish this work under a different plugin some time in the future.

What is this

This is a plugin for pretix. This plugin supports both Ethereum and DAI.

History

It started with ligi suggesting pretix for Ethereum Magicians.

Then it was used for Ethereum Magicians in Paris (shout out to boris for making this possible) - but accepting ETH or DAI was a fully manual process there.

Afterwards boris put up some funds for a gitcoin bounty to make a plugin that automates this process. And nanexcool increased the funds and added the requirement for DAI.

The initial version was developed by vic-en but he vanished from the project after cashing in the bounty money and left the plugin in a non-working state.

Then the idea came up to use this plugin for DevCon5 and the plugin was forked to this repo and ligi, david sanders, piper meriam, rami, Pedro Gomes, and Jamie Pitts brought it to a state where it is usable for DevCon5 (still a lot of work to be done to make this a good plugin). Currently, it is semi-automatic. But it now has ERC-681 and Web3Modal support. If you want to dig a bit into the problems that emerged short before the launch you can have a look at this issue

For DEVcon6 the plugin was extended with some more features like Layer2 support by Rahul. Layer2 will play a significant role in Ethereum. Unfortunately DEVcon6 was delayed due to covid - but we where able to use and this way test via the LisCon ticket sale. As far as we know this was the first event ever offering a Layer2 payment option. In the process tooling like Web3Modal / Checkout that we depend on was improved.

For Devconnect IST an effort was made to improve the plugin in a variety of ways: WalletConnect support, single receiver mode (accept payments using just one wallet), more networks, automatic ETH rate fetching, improved UI and messaging, and smart contract wallet support. All of these features made it into this version of the plugin, except for smart contract wallet support - issues processing transactions stemming from sc wallets meant that we ultimately had to turn away sc wallet payments altogether.

If you are a dev and want to "finish" the plugin by adding smart contract wallet support, the main thing missing is the ability to verify the sender+receiver addresses and the amount sent given a tx hash stemming from a smart contract wallet. Smart contract transaction receipts aren't easy to process because the "to" and "value" field are not useful - to get the actual receiver wallet and the amount sent, more complex processing is needed (presumably by looking at the transaction logs - but it has to be generic, because each sc wallet has different internals). ERC1271 support is already added, so it really is just about building this "verifier".

Recently added features

• A payment confirmation management command was added that confirms pending payments based on the address assigned to them during checkout. See the confirm_payments section below for details.
• "Single receiver" mode (accept all payments using just one wallet)
• WalletConnect support
• Automatic ETH rate fetching
• More L2s added
• Updated user-facing UI and error messaging
• ERC1271 support (note: smart contract payments not yet fully supported - the confirm payment cannot handle sc wallet payments, see warning above for details)

Development setup

1. Clone this repository, e.g. to local/pretix-eth-payment-plugin.
2. Create and activate a virtual environment.
3. Execute pip install -e .[dev] within the pretix-eth-payment-plugin repo directory.
4. Setup a local database by running make devmigrate.
5. Fire up a local dev server by running make devserver.
6. Visit http://localhost:8000/control/login in a browser windows and enter username admin@localhost and password admin to log in.
7. Enter "Admin mode" by clicking the "Admin mode" text in the upper-right corner of the admin interface to create a test organization and event.
8. Follow instructions in Event Setup Instructions
9. If you need to update web3modal/walletconnect related code, this happens in the web3modal folder - check the README there.

Event Setup Instructions

1. Under the event, go to Settings -> Plugins -> Payment Providers -> click on Enable under "Pretix Ethereum Payment Provider"
2. Next, under Settings, go to Payments -> "ETH or DAI" -> Settings -> click on "enable payment method".
3. Next, scroll down and set the values for the following:

• "TOKEN_RATE" - This is a JSON e.g.

  {"ETH_RATE": 4000, "DAI_RATE": 1}
  

  i.e. KEY = <CRYPTO_SMBOL>_RATE and VALUE = value of 1 unit in your fiat currency e.g. USD, EUR etc. For USD, above example says 1 ETH = 4000$. If EUR was chosen, then this says 1 ETH = 4000EUR.

  Note that the Ethereum rate will automatically reflect the current market price (regardless of which ETH_RATE you put in the config) - the ETH_RATE you define here is a fallback in the unlikely scenario that the plugin price feeds are down. The ETH_RATE will ONLY automatically reflect the current market price when Event Currency is set to either USD or EUR. If you set your event currency to ANYTHING ELSE the ETH rate will not automatically reflect its market price - it must then be manually input & updated regularly.

• Select the networks you want under the "Networks" option - Choose from Ethereum Mainnet, Optimism, Arbitrum and their testnets.

• "NETWORK_RPC_URLS" - This is a JSON e.g.

  {
    "L1_RPC_URL": "https://mainnet.infura.io/v3/somekeyhere",
    "Rinkeby_RPC_URL": "...",
    "RinkebyArbitrum_RPC_URL": "..."  
  }
  

  i.e. KEY = <Network ID>_RPC_URL and VALUE = RPC URL. Network IDs can be found in tokens.py

• "Payment receiver address" - Ethereum address at which all payments will be sent to

• "WalletConnect project ID" - WalletConnect requires a project id - you can generate one on https://walletconnect.com/

You can now play with the event by clicking on the "Go to Shop" button at the top left (next to the event name)

Automatic payment confirmation with the confirm_payments command

This plugin includes a django management command that can be used to automatically confirm orders from the Ethereum address associated with each order across all events. By default, this command will perform a dry run which only displays payment records that would be modified and why but without actually modifying them.

Here's an example invocation of this command:

python -mpretix confirm_payments \
    --no-dry-run

Note that this doesn't require you to pass any event slug, since it runs for all events at once. It inspects the address that was associated with each order (at the time the ticket was reserved) to determine if sufficient payments were made for the order. It may check for an ethereum payment or some kind of token payment depending on what was chosen during the checkout process. It checks using the RPC URLs that were configured in the admin settings while setting up the event. If no rpc urls were set, then the command gives yet another chance to type in a rpc url (like infura). The --no-dry-run flag directs the command to update order statuses based on the checks that are performed. Without this flag, the command will only display how records would be modified.

For more details about the confirm_payments command and its options, the command may be invoked with --help:

python -mpretix confirm_payments --help

License

Copyright 2019 Victor (https://github.com/vic-en)

Released under the terms of the Apache License 2.0