ethapi: add personal.signTransaction

[holiman]

This pr adds personal.signTransaction( <tx> , <pw>) , which is a deficiency at the moment.

In order to create offline transactions, there's currently no great way to accomplish that:

1. Use personal.unlock and then eth.signTransaction
   • unlockis dangerous for various reasons
2. Start geth in --nodiscover --maxpeers=0, and use personal.sendTransaction(<tx>,<pw>).
   • This is also dangerous, since locally submitted transactions are stored in transactions.rlp, and geth will broadcast these on the next startup unless the file is deleted.

This pr resolves #15953

[karalabe]

Seems like an awfully lot of duplicated code. Can't we make SendTransaction call SignTransaction and submit the transaction at the end (instead of having the same thing copy-pasted twice)?

[karalabe]

Or if we want to avoid the RLP encoding, then perhaps make a common step that just returns the signer transaction and then SendTransaction can submit it, whilst SignTransaction can RLP encode and return it.

[holiman]

Fixed, PTAL

[karalabe]

Should we allow passing in a nil nonce/gaslimit/gasprice here? The only meaningful reason to not submit a transaction is if the node is not in sync (not yet or offline). If the node is not in sync however, we don't know the nonce, the gas limit cannot be estimated without the required contracts/states and the gasprice will be dangerous as it's some past one.

[karalabe]

I think it would be safer to explicitly disallow the nil fields, instead of deal with the slew of bugreports from people "using it wrong".

[holiman]

So, my primary usecase is offline transactions, and in those cases the user should supply all values himself, rather than rely on defaults. So I'm ok with that..
So, should we explicitly check that these fields are not nil:

	args.Gas
        args.GasPrice
	args.Nonce

(and still call SetDefault after that check has passed)

?

[holiman]

Hold on though. We already have eth.signTransaction. Don't we want those two to behave identically? If so, old or new behaviour?

[holiman]

PTAL, changed the behaviour of personal/eth.signTransaction to fail on missing nonce/gas/gasPrice

[holiman]

Testing:

> personal.signTransaction({from: eth.accounts[1], to:eth.accounts[1]},"test")
Error: gas not specified
    at web3.js:3143:20
    at web3.js:6347:15
    at web3.js:5081:36
    at <anonymous>:1:1

> personal.signTransaction({from: eth.accounts[1], to:eth.accounts[1], gas:1},"test")
Error: gasPrice not specified
    at web3.js:3143:20
    at web3.js:6347:15
    at web3.js:5081:36
    at <anonymous>:1:1

> personal.signTransaction({from: eth.accounts[1], to:eth.accounts[1],gas:1, gasPrice:1},"test")
Error: nonce not specified
    at web3.js:3143:20
    at web3.js:6347:15
    at web3.js:5081:36
    at <anonymous>:1:1

> personal.signTransaction({from: eth.accounts[1], to:eth.accounts[1],gas:1, gasPrice:1, nonce:1},"test")
{
  raw: "0xf85d01010194f3b3138e5eb1c75b43994d1bb760e2f9f735789680801ca08f8e7cb8d999250a30662a7b11d44afe808f7f9103bc80447599de46251bdcf7a00bc1ddff1fdd1d2c2496807c17cd1d33842fd394a066fb2a51b354a0c2b8d731",
  tx: {
    gas: "0x1",
    gasPrice: "0x1",
    hash: "0x6cb39e49763bc56a10016c8ea94aa9b8585b3037bc93c219ccb5d314cd3363e0",
    input: "0x",
    nonce: "0x1",
    r: "0x8f8e7cb8d999250a30662a7b11d44afe808f7f9103bc80447599de46251bdcf7",
    s: "0xbc1ddff1fdd1d2c2496807c17cd1d33842fd394a066fb2a51b354a0c2b8d731",
    to: "0xf3b3138e5eb1c75b43994d1bb760e2f9f7357896",
    v: "0x1c",
    value: "0x0"
  }
}
> personal.unlockAccount(eth.accounts[1],"test")
true

> eth.signTransaction({ from: eth.accounts[1], to: eth.accounts[1], value:0})
Error: gas not specified
    at web3.js:3143:20
    at web3.js:6347:15
    at web3.js:5081:36
    at <anonymous>:1:1

> eth.signTransaction({ from: eth.accounts[1], to: eth.accounts[1], gas:0})
Error: gasPrice not specified
    at web3.js:3143:20
    at web3.js:6347:15
    at web3.js:5081:36
    at <anonymous>:1:1

> eth.signTransaction({ from: eth.accounts[1], to: eth.accounts[1], gas:0, gasPrice:1})
Error: nonce not specified
    at web3.js:3143:20
    at web3.js:6347:15
    at web3.js:5081:36
    at <anonymous>:1:1

> eth.signTransaction({ from: eth.accounts[1], to: eth.accounts[1], gas:0, gasPrice:1, nonce:1})
{
  raw: "0xf85d01018094f3b3138e5eb1c75b43994d1bb760e2f9f735789680801ca06484d00575e961a7db35ebe5badaaca5cb7ee65d1f2f22f22da87c238b99d30da07a85d65797e4b555c1d3f64beebb2cb6f16a6fbd40c43cc48451eaf85305f66e",
  tx: {
    gas: "0x0",
    gasPrice: "0x1",
    hash: "0x0a32fb4e18bc6f7266a164579237b1b5c74271d453c04eab70444ca367d38418",
    input: "0x",
    nonce: "0x1",
    r: "0x6484d00575e961a7db35ebe5badaaca5cb7ee65d1f2f22f22da87c238b99d30d",
    s: "0x7a85d65797e4b555c1d3f64beebb2cb6f16a6fbd40c43cc48451eaf85305f66e",
    to: "0xf3b3138e5eb1c75b43994d1bb760e2f9f7357896",
    v: "0x1c",
    value: "0x0"
  }
}

[karalabe]

LGTM