What is this?

This is a stand-alone P2P transaction submission tool.

The motivation for this command is the -walletbroadcast=0 command introduced in Bitcoin Core 0.11 (see the release notes.)

Dependencies

This tool uses python-bitcoinlib, which can be installed using:

pip3 install --user python-bitcoinlib

Alternatively, to go without installing anything, clone the git repository and symlink the bitcoin directory inside into the root of this repository.

Usage

Usage:

usage: bitcoin-submittx [-h] [--proxy PROXY] [--timeout TIMEOUT] [--no-color]
                        [--nodes-file NODES_FILE] [--tx-file TX_FILE]
                        NETWORK TXHEX [NODES [NODES ...]]

Transaction submission tool

positional arguments:
  NETWORK               Network to connect to (mainnet, regtest, testnet).
                        This also determines the default port
  TXHEX                 Serialized transactions to broadcast, separated by
                        commas
  NODES                 Nodes to connect to, denoted either host or host:port

optional arguments:
  -h, --help            show this help message and exit
  --proxy PROXY, -p PROXY
                        SOCKS5 proxy to connect through
  --timeout TIMEOUT, -t TIMEOUT
                        Number of seconds to wait before disconnecting from
                        nodes (default is 10)
  --no-color            Use no terminal color in output
  --nodes-file NODES_FILE, -n NODES_FILE
                        Read list of nodes from file (format: one per line)
  --tx-file TX_FILE, -r TX_FILE
                        Read list of transactions from file (format: one per
                        line)

The tool will connect to the provided nodes and announce the transactions. If the nodes subsequently request them within the timeout, they are sent.

The return status of the program will be 0 if at least one node requested the transaction, and 1 otherwise.

Example w/ Bitcoin Core

• Send the transaction as normal, either e.g. through RPC sendtoaddress or the GUI

$ bitcoin-cli sendtoaddress mjqhocRebTHZRhkbkQs8Uzzb1T3GhEvEB4 0.25
f91948e5...

• Using the transaction hash, retrieve the transaction data through RPC using gettransaction (NOT getrawtransaction). The hex field of the result will contain the raw hexadecimal representation of the transaction

$ bitcoin-cli gettransaction f91948e5...
{
  ...
  "txid": "f91948e5...",
  ...
  "hex": "010000000..."
}

• Provide the hex field as TXHEX to this tool. e.g.

$ bitcoin-submittx mainnet '010000000...' 127.0.0.1

(normally one would not submit the transaction to the localhost node, but this is just an illustrative example)

Segwit support

As of 2017-11-30, this requires the master version of python-bitcoinlib. Version 0.8 fails with bitcoin.core.serialize.DeserializationExtraDataError: Not all bytes consumed during deserialization.

A known issue is that bitcoin-submittx invs the wtxid instead of the txid, but when it sends the tx the node accepts it. This is probably not correct per BIP141. Patches welcome!

Fork support

bitcoin-submittx

• can be used for BCH by passing BCH nodes, and using the mainnet network parameter.

• can be used for BSV by passing BSV nodes, and using the mainnet network parameter.

• can be used for BTG by passing BTG nodes, and using the btg-mainnet network parameter.

• can be used for BCX by passing BCX nodes, and using the bcx-mainnet network parameter.

You can find nodes for the appropriate fork on https://bitnodes.earn.com/, or by manually querying their DNS seed.

TODOs and contribution ideas

• Automatically fetch list of nodes to submit to
  • possibly from DNS seeds (but this won't work behind Tor)
• IPv6 support
• Provide feedback of transaction reach, e.g. when connected to multiple nodes, it could monitor if the transaction comes back via another route.
• Tor stream isolation (like -proxyrandomize in Bitcoin Core)
• Multi-hop proxies, different proxy types?
• Feature to handle incoming connections: can be handy when submitting transactions to nodes that are not listening for e.g. testing

Other projects

Some other projects that might be useful when working with bitcoin transactions at a low level:

• payment-proto-interface This is a simple (Python) application which allows you to interact with the Bitcoin payment protocol manually