Meta transaction (a.k.a. Gasless transactions) using ethers.js

[digvjs]

Is there a way to implement a meta transaction using ethers.js library.

Consider a transaction to transfer 100 tokens from 0xAccountA to 0xAccountB. The transaction will be signed by 0xAccountA but the gas would be payed by some other 0xAccountC.

[ricmoo]

I have not actually used Meta-transactions yet, but all the necessary functions should certainly be available. I will be bugging the metatx cartel during DevCon5 to get caught up on the latest techniques. :)

[digvjs]

I have not actually used Meta-transactions yet, but all the necessary functions should certainly be available. I will be bugging the metatx cartel during DevCon5 to get caught up on the latest techniques. :)

Is there any discussion channel such for this thing?

[ricmoo]

There may be an ETH Magicians event for it, otherwise I'm sure they will post something. I just haven't had time to look into it yet. Feel free to look it up and let me know. ;)

[Amxx]

Each wallet has it's own meta-transaction format & signature. So I don't really think there is a "generic" way for ethers to support meta-tx. However, ethers can (and is already) used to build wallet specific tolling. For exemple, this is my SDK for doing metatransaction with (my) KitsuneWallets:

• https://github.com/Amxx/KitsuneWallet-ERC1836/blob/ERC712/kitsune-sdk/lib/modules/Multisig.ts
• https://github.com/Amxx/KitsuneWallet-ERC1836/blob/ERC712/kitsune-sdk/lib/modules/Meta.ts

[ricmoo]

Awesome, thanks! I’ll look into that.

I thought the meta-ts cartel was trying to create a standard so that relay networks (or whatever they are called) can be used as a market to make meta-tax reliable... I honesty haven’t looked into it enough though since the eth magicians last DevCon...

[Amxx]

More and more people are moving away from the relay gas network due to it's (many) limitations. Universal Login (for one) is not compatible (that I'm sure of) ... I also suspect argent/other to not be compatible. I'll be in Devcon, reach me @amxx (ethereum-magicians / twitter) if you want to discuss that

[marcelomorgado]

I think it's related to https://github.com/OpenZeppelin/openzeppelin-gsn-provider

[ricmoo]

I'm going to track this (GSN and meta-transactions in general) in #636, so I'll close this issue.

@yuetloo has started looking into it and figuring out how to create a GsnSigner. :)

[joeb000]

@ricmoo just FYI I am working on extending ethers.js to add an intuitive way for Dapp devs to integrate meta transactions into their dapp with only a couple lines of code.

I am imagining something like this:

    const metaConfig = {
        relayerURL: "https://somerelayernode.com",
        metaType: "erc1776" // metamask Generalized MetaTransaction Contest winner: https://github.com/wighawag/singleton-1776-meta-transaction
    }
    const metaSigner = provider.getMetaSigner(metaConfig)
    const metaContract = new ethers.MetaContract(address, abi, metaSigner)

    // call it just like you would with a normal ethers contract
    let metaTx = await metaContract.someFunction(param1, param2)

Basically allow dapp devs using ethers to set their relayer and metaType in a config object and initialize a MetaSigner (extension of Signer) which instead of signing a transaction and POSTing to the Provider's URL, it will sign a meta transaction (in the above example with signTypedData_v4) and send the signed meta transaction hex string to the relayerURL.

To pilot this concept I extended ethers.js with my own meta-ethers library and used my own simplified meta transaction schema. My experiments have gone very well, so I am now working on forking ethers.js base code to build this functionality into the native ethers.js source code itself. Will post back here when I have anything worthy of review/beta testing.

[holgerd77]

Can't this be done in a more modular/plugin-like way? Also question for @ricmoo

[ricmoo]

I don't know how those last few comments slipped past me...

@yuetloo has a working GsnSigner, which is just another normal ethers Signer, there shouldn't be any need to fork ethers.Basically, you instantiate a GsnSigner and just use ethers normally, except all transactions just happen over the GSN, no additional changes are needed by users.

I haven't had a chance to do the code review yet, but she her fork and changes are available. :)

This will be added to the experimental package at first, until it is stable, but yes this would eventually be its own sub-package, or may be bundled with similar Signers, but will be under a @ethersproject/ package in the packages/ folder.