internal/ethapi: implement fillTransaction

[holiman]

This PR adds eth.fillTransaction, which is useful if signing is done outside of the actual node.

Below is a reference about what methods exist today (we might want to make it into a table and place in the docs)

Example

Example when using geth --dev, which does not really have a sensible GPO.

> eth.fillTransaction({"to":"0x17Ff1b635D4A1E4Ba1377E06d1dD0e1C9015FB5f", value:"100", from:"0x17Ff1b635D4A1E4Ba1377E06d1dD0e1C9015FB5f"})
{
  raw: "0xdf80018252089417ff1b635d4a1e4ba1377e06d1dd0e1c9015fb5f6480808080",
  tx: {
    gas: "0x5208",
    gasPrice: "0x1",
    hash: "0xea7d97f5fe68d9fc638410cf134f3785ef690330660069252e5d7bb2f122f6c7",
    input: "0x",
    nonce: "0x0",
    r: "0x0",
    s: "0x0",
    to: "0x17ff1b635d4a1e4ba1377e06d1dd0e1c9015fb5f",
    v: "0x0",
    value: "0x64"
  }
}

Transaction methods

Namespace	Function	Broadcasts	Requires accounts	Output	Fills defaults
eth	sendTransaction	Yes	Yes	hash	Yes
eth	sendRawTransaction	Yes	No	hash	No
eth	signTransaction	No	Yes	RLP + JSON (signed tx)	No
eth	resend	Yes	Yes	hash	Yes
eth	fillTransaction	No	No	RLP+JSON (unsigned tx)	Yes
personal	sendTransaction	Yes	Yes	hash	Yes
personal	signTransaction	No	Yes	RLP+JSON (signed tx)	No

• eth.sendTransaction
  • Creates a transaction from input, sign it and broadcast
  • Sets defaults
• eth.sendRawTransaction
  • Takes a fully complete (filled and signed) transactoin in RLP-form, and broadcasts
• eth.signTransaction
  • Takes a fully filled (unsigned) transaction, signs and broadasts
• eth.resend
  • Matches nonce if sending-account to an existing tx, applies modifications, signs and broadcasts
  • Requires nonce, fills other defaults
• eth.fillTransaction
  • Fills defaults and returns RLP + JSON
• personal.sendTransaction
  • Creates a transaction from input, fills defaults, sign it and broadcast
• personal.signTransaction
  • Creates a fully filled transaction from input, sign it and returns RLP + JSON

[holiman]

Fixed, ptal

[karalabe]

Hmmm, shouldn't we perhaps declare a type FillTransactionResult that does not return R, S, V?

[holiman]

Hm, maybe... I'm not sure it solves the usability question. So here are the steps you need to go through to actually fill and sign a tx:

> a = eth.fillTransaction({"to":"0x17Ff1b635D4A1E4Ba1377E06d1dD0e1C9015FB5f", value:"100", from:eth.accounts[0]})
{
  raw: "0xdf80018252089417ff1b635d4a1e4ba1377e06d1dd0e1c9015fb5f6480808080",
  tx: {
    gas: "0x5208",
    gasPrice: "0x1",
    hash: "0xea7d97f5fe68d9fc638410cf134f3785ef690330660069252e5d7bb2f122f6c7",
    input: "0x",
    nonce: "0x0",
    r: "0x0",
    s: "0x0",
    to: "0x17ff1b635d4a1e4ba1377e06d1dd0e1c9015fb5f",
    v: "0x0",
    value: "0x64"
  }
}
> a.tx.from = eth.accounts[0]
"0x42e44603164ac2384c2c0894fe67b344a9f1f50b"
> eth.signTransaction(a.tx)
{
  raw: "0xf86180018252089417ff1b635d4a1e4ba1377e06d1dd0e1c9015fb5f6480820a95a013c4a9a47cd447a6bef6a085b20e02ae393205bac903e74535c103c33bc54021a02d0ef0739ebd9267197625c0fb154619b0e385066e362dbac55fbdf57e68773a",
  tx: {
    gas: "0x5208",
    gasPrice: "0x1",
    hash: "0x656acc325802797f991d98ba48f8bd383332bcdbc4c390ac790740139c1adfe9",
    input: "0x",
    nonce: "0x0",
    r: "0x13c4a9a47cd447a6bef6a085b20e02ae393205bac903e74535c103c33bc54021",
    s: "0x2d0ef0739ebd9267197625c0fb154619b0e385066e362dbac55fbdf57e68773a",
    to: "0x17ff1b635d4a1e4ba1377e06d1dd0e1c9015fb5f",
    v: "0xa95",
    value: "0x64"
  }
}

You need to explicitly set the from. Would be neat if we could pass the output from fill as input to sign.

[karalabe]

LGTM