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Proposal:-Transaction-Proxy-Hooks.md

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Requirements

Need an abstraction mechanism to allow ÐApps like the Wallet provide their services in an integrated manner without compromising the neutrality of the browser or placing undue burden on third-party ÐApp developers to support them.

Basic Design

The ethereum.js interface may be utilised to allow the ÐApp client to register itself as the transaction handler for each of a number of accounts; in doing so it will provide an additional callback.

This is done through one addition to the ethereum.js web3.eth object, registerProxyTransactor:

var addresses = [];
// TODO: populate addresses

function f(tx) {
  // tx includes tx.from, tx.to, tx.data, tx.value, tx.gasPrice, tx.gas
  // and is *exactly* the same as what was passed to eth.transact, but probably not in this
  // JS environment.
  // tx.from is guaranteed to be an element of addresses.
  // TODO: do something
}

web3.eth.registerProxyTransactor(addresses, f);

That's the entire JS API.

In terms of JSON-RPC, there must be an alteration to eth_accounts: rather than just including the accounts that we have the secret key for (and that the user has accepted are valid for this dapp to use and know about), all accounts passed as the first argument to registerProxyTransactor should also be contained (with the same safeguards as per user acceptance).

There are also two additional calls in the JSON-RPC; one for polling the status of whether any transactions are waiting to be signed by our callback that we registered as the second argument of registerProxyTransactor, and one for letting the core know that our ethereum.js object is capable of proxying transactions sent from the addresses passed as the first argument of registerProxyTransactor.

The first is eth_registerAddressHandler; it takes one argument which is an array of addresses and returns an integer identifier. Any otherwise unsignable transactions whose from address is included in this array should be, at some time later, returned to this session as a result of polling the RPC function eth_checkProxyTransactions.

eth_checkProxyTransactions takes one argument - the previous integer identifier and returns an array of transactions, each of the form that are passed to web3.eth.transact.

Core

Cores must maintain queues of proxy transactions together with sets of addresses, one each per ethereum.js web3.eth object (identified through the integer returned to eth_registerAddressHandler and provided by eth_checkProxyTransactions). These transactions are to be returned to the session via eth_checkProxyTransactions. They are to be filled whenever an eth_transact is called (from any session) with a from address that is contained in the corresponding set of proxyable addresses.

Notes

If it's called twice, all previous state associated with it is replaced. If two ethereum.js web3.eth objects both try to handle the same address, the first one wins and the second silently fails.

NatSpec messages should be shown for all transactions, ideally only a single ultimate user action required for any given high-level transaction. E.g.:

  • Send 56 ether to Dave - 0x56789123 from account Gav's Bank Account - 0x12345678.
  • Wallet ÐApp handling account Gav's Bank Account - 0x12345678 requests authorisation to conduct the above through: Message from Gav - 0x34343455 to Gav's Bank Account - 0x12345678 to: Send 56 ether to Dave - 0x56789123.

The first NatSpec line just corresponds to the first bare and impossible-to-sign transaction from a contract. The second is the actual transaction that will be signed, stating that Gav (the account for which we have a secret key), would sign a transaction instructing the wallet to send the funds.