Relay mempool transactions based on the ZIP-317 fee rules

[teor2345]

Motivation

We want to deploy the new relaying rules in ZIP-317, once enough wallets have updated:

Node developers SHOULD coordinate on schedules for deploying restrictions to their policies for transaction mempool acceptance and peer-to-peer relaying. These policy changes SHOULD NOT be deployed before the changes to transaction inclusion policy by miners described in the preceding paragraph.

https://zips.z.cash/zip-0317#deployment

This might happen in late 2022 or early 2023.

Specification

The relay part of: https://zips.z.cash/zip-0317#transaction-relaying

Design

Zebra currently relays all transactions, but we should consider doing whatever zcashd does for their ZIP 317 implementation.

As an alternative, we can relay transactions with a probability proportional to transaction_fee / conventional_fee.

[dconnolly]

We want to deploy the new relaying rules in ZIP-317 after most wallets have updated to the new conventional fee.

'The eviction weight is already proportional to the size of the transaction in bytes', so we should be able to deploy these changes before wallets do without negative effect (per daira). What will happen in practice is regardless of whether an attacker chooses big transactions or lots of smaller transactions, the total size of their transactions will be large compared to the legitimate ones, it will always be more likely that the adv. 's transactions will be dropped vs legitimate ones. // @daira

[teor2345]

@dconnolly you wrote in the description:

This is not necessarily contingent on a plurality of wallets adopting the new fee:

But the advice in the ZIP is to coordinate deployment of relaying changes with zcashd and wallets.

[mpguerra]

Hey team! Please add your planning poker estimate with Zenhub @arya2 @conradoplg @oxarbitrage @teor2345 @upbqdn

[daira]

We want to deploy the new relaying rules in ZIP-317 after most wallets have updated to the new conventional fee.

'The eviction weight is already proportional to the size of the transaction in bytes', so we should be able to deploy these changes before wallets do without negative effect (per daira). What will happen in practice is regardless of whether an attacker chooses big transactions or lots of smaller transactions, the total size of their transactions will be large compared to the legitimate ones, it will always be more likely that the adv. 's transactions will be dropped vs legitimate ones. // @daira

This was about mempool eviction (i.e. ZIP 401), not relaying.

[teor2345]

This ticket is currently blocked by the deployment of similar changes to wallets.