[Wallet][RPC] FundTransaction - fundrawtransaction

[random-zebra]

based on top of

• [Cleanup] Remove obsolete multisig code #1662

This introduces a new wallet function, CWallet::FundTransaction() (and exposes it via RPC with fundrawtransaction), to fill a tx containing only vouts (or not enough vins to cover the vouts) with unspent coins from the wallet.

fundrawtransaction will not modify existing inputs, and will add one change output (if needed) to the outputs. It will not sign the inputs (so can include also watch-only or multi-sig inputs, if enabled).

backported from:

• fundrawtransaction bitcoin/bitcoin#6088
• wallet: allow transaction without change if keypool is empty bitcoin/bitcoin#17219 [*]
• [QA] fix possible reorg issue in (fund)rawtransaction(s).py RPC test bitcoin/bitcoin#6417
• Exempt unspendable transaction outputs from dust checks bitcoin/bitcoin#6444
• Implement watchonly support in fundrawtransaction bitcoin/bitcoin#6415
• [rpc-tests] fundrawtransaction: Update fee after minRelayTxFee increase bitcoin/bitcoin#6828
• Add sane fallback for fee estimation bitcoin/bitcoin#7296 (only bebe58b)
• Use CCoinControl selection in CWallet::FundTransaction bitcoin/bitcoin#7506
• Add multiple options to fundrawtransaction bitcoin/bitcoin#7518
• [RPC] add feerate option to fundrawtransaction bitcoin/bitcoin#7967

adapting the tests for the (more recent) framework.

[*] Note: this has been included to be able to call fundrawtransaction without the need for an unencrypted wallet (for the change address key)

[random-zebra]

Rebased. Ready for review/QA.

[ambassador000]

fundrawtransaction RPC command is working as intended (also with encrypted wallet), however I couldn't get working createrawtransaction and signrawtransaction commands, always ended up with various errors, probably because of the confusing input format needed.

[random-zebra]

@NoobieDev12 , what kind of errors?
It should be straightforward.
Here's a brief tutorial to (1) create, (2) fund, (3) sign, and (4) broadcast a transaction:

1. Create a transaction without inputs (empty list []), only outputs (dictionary {"address": amount}):

$ ./pivx-cli createrawtransaction '[]' '{"yCrjZ7EcS2y7jFo48dMvmUxPtp1fTt9W4U": 100}'

01000000000100e40b54020000001976a914ae29d55979ebcaceccf4d660810a3390e728b5fa88ac00000000

2. Fund the transaction (i.e. add enough inputs to cover the output values):

$ ./pivx-cli fundrawtransaction 01000000000100e40b54020000001976a914ae29d55979ebcaceccf4d660810a3390e728b5fa88ac00000000

{
  "hex": "01000000014da53ec78886990bb07b27ab9ce67cc586be60c58cdc622bd35380657219a57f0000000000ffffffff02ace41b78030000001976a914d764b754e913a26bce160c6a5ca2c1c20ebb8dc588ac00e40b54020000001976a914ae29d55979ebcaceccf4d660810a3390e728b5fa88ac00000000",
  "changepos": 0,
  "fee": 0.00002260
}

3. The raw transaction ("hex" string from the output of the previous command) is unsigned, as we can see decoding it:

$ ./pivx-cli decoderawtransaction 01000000014da53ec78886990bb07b27ab9ce67cc586be60c58cdc622bd35380657219a57f0000000000ffffffff02ace41b78030000001976a914d764b754e913a26bce160c6a5ca2c1c20ebb8dc588ac00e40b54020000001976a914ae29d55979ebcaceccf4d660810a3390e728b5fa88ac00000000

{
  "txid": "0d9ab9ea5324fc9d3d7ce98bf8b4e3bf722fc0404d105b42fd4f9b8ac7cbbcb0",
  "version": 1,
  "size": 119,
  "locktime": 0,
  "vin": [
    {
      "txid": "7fa51972658053d32b62dc8cc560be86c57ce69cab277bb00b998688c73ea54d",
      "vout": 0,
      "scriptSig": {
        "asm": "",
        "hex": ""
      },
      "sequence": 4294967295
    }
  ],
  ...
}

Let's add the signatures to the input:

$ ./pivx-cli signrawtransaction 01000000014da53ec78886990bb07b27ab9ce67cc586be60c58cdc622bd35380657219a57f0000000000ffffffff02ace41b78030000001976a914d764b754e913a26bce160c6a5ca2c1c20ebb8dc588ac00e40b54020000001976a914ae29d55979ebcaceccf4d660810a3390e728b5fa88ac00000000

{
  "hex": "01000000014da53ec78886990bb07b27ab9ce67cc586be60c58cdc622bd35380657219a57f000000006a4730440220546266cdd03230f0c7c71aed643704651c50228c910b102c36d96780ec14c02f0220152ff071e9d67a836c7fbcc5c019e072692a836e8210830de17c5aa3501676aa012102271fb71ea03d9c9d6014d192dcda21de7d47f9044f6786b72761fb9c7034c162ffffffff02ace41b78030000001976a914d764b754e913a26bce160c6a5ca2c1c20ebb8dc588ac00e40b54020000001976a914ae29d55979ebcaceccf4d660810a3390e728b5fa88ac00000000",
  "complete": true
}

4. The transaction (again "hex" string from the output of the previous command) is now signed:

$ ./pivx-cli decoderawtransaction 01000000014da53ec78886990bb07b27ab9ce67cc586be60c58cdc622bd35380657219a57f000000006a4730440220546266cdd03230f0c7c71aed643704651c50228c910b102c36d96780ec14c02f0220152ff071e9d67a836c7fbcc5c019e072692a836e8210830de17c5aa3501676aa012102271fb71ea03d9c9d6014d192dcda21de7d47f9044f6786b72761fb9c7034c162ffffffff02ace41b78030000001976a914d764b754e913a26bce160c6a5ca2c1c20ebb8dc588ac00e40b54020000001976a914ae29d55979ebcaceccf4d660810a3390e728b5fa88ac00000000

{
  "txid": "6751d397bc4e97bf444248844b783b83f652a4fb900d4df85fb148b9f89ee86d",
  "version": 1,
  "size": 225,
  "locktime": 0,
  "vin": [
    {
      "txid": "7fa51972658053d32b62dc8cc560be86c57ce69cab277bb00b998688c73ea54d",
      "vout": 0,
      "scriptSig": {
        "asm": "30440220546266cdd03230f0c7c71aed643704651c50228c910b102c36d96780ec14c02f0220152ff071e9d67a836c7fbcc5c019e072692a836e8210830de17c5aa3501676aa[ALL] 02271fb71ea03d9c9d6014d192dcda21de7d47f9044f6786b72761fb9c7034c162",
        "hex": "4730440220546266cdd03230f0c7c71aed643704651c50228c910b102c36d96780ec14c02f0220152ff071e9d67a836c7fbcc5c019e072692a836e8210830de17c5aa3501676aa012102271fb71ea03d9c9d6014d192dcda21de7d47f9044f6786b72761fb9c7034c162"
      },
      "sequence": 4294967295
    }
  ],
  ...
}

Let's broadcast it to the network:

$ ./pivx-cli sendrawtransaction 01000000014da53ec78886990bb07b27ab9ce67cc586be60c58cdc622bd35380657219a57f000000006a4730440220546266cdd03230f0c7c71aed643704651c50228c910b102c36d96780ec14c02f0220152ff071e9d67a836c7fbcc5c019e072692a836e8210830de17c5aa3501676aa012102271fb71ea03d9c9d6014d192dcda21de7d47f9044f6786b72761fb9c7034c162ffffffff02ace41b78030000001976a914d764b754e913a26bce160c6a5ca2c1c20ebb8dc588ac00e40b54020000001976a914ae29d55979ebcaceccf4d660810a3390e728b5fa88ac00000000

6751d397bc4e97bf444248844b783b83f652a4fb900d4df85fb148b9f89ee86d

[furszy]

Code review ACK 5a41ebb.

[furszy]

Working as intended 👌 , tested ACK 5a41ebb.

[ambassador000]

Thanks for the detailed reply and explanation RZ!
All working now! However, just for the reference, I cannot reproduce it again, but yesterday at some point using the fundrawtransaction I got the "changepos": -1, output. Other errors were mostly related to invalid inputs and are irrelevant because of that.

[Fuzzbawls]

Needs a rebase, but otherwise ACK

[random-zebra]

Rebased, and added one last case to the functional test.

[furszy]

re ACK fc81158 .

[Fuzzbawls]

ACK fc81158