chaincfg

Documentation

Overview

Package chaincfg defines chain configuration parameters.

In addition to the main Bitcoin network, which is intended for the transfer of monetary value, there also exists two currently active standard networks: regression test and testnet (version 3). These networks are incompatible with each other (each sharing a different genesis block) and software should handle errors where input intended for one network is used on an application instance running on a different network.

For library packages, chaincfg provides the ability to lookup chain parameters and encoding magics when passed a *Params. Older APIs not updated to the new convention of passing a *Params may lookup the parameters for a wire.BitcoinNet using ParamsForNet, but be aware that this usage is deprecated and will be removed from chaincfg in the future.

For main packages, a (typically global) var may be assigned the address of one of the standard Param vars for use as the application's "active" network. When a network parameter is needed, it may then be looked up through this variable (either directly, or hidden in a library call).

package main

import (
        "flag"
        "fmt"
        "github.com/mit-dci/lit/logging"

        "github.com/mit-dci/lit/btcutil"
        "github.com/mit-dci/lit/btcutil/chaincfg"
)

var testnet = flag.Bool("testnet", false, "operate on the testnet Bitcoin network")

// By default (without -testnet), use mainnet.
var chainParams = &chaincfg.MainNetParams

func main() {
        flag.Parse()

        // Modify active network parameters if operating on testnet.
        if *testnet {
                chainParams = &chaincfg.TestNet3Params
        }

        // later...

        // Create and print new payment address, specific to the active network.
        pubKeyHash := make([]byte, 20)
        addr, err := btcutil.NewAddressPubKeyHash(pubKeyHash, chainParams)
        if err != nil {
                logging.Fatal(err)
        }
        fmt.Println(addr)
}

If an application does not use one of the three standard Bitcoin networks, a new Params struct may be created which defines the parameters for the non-standard network. As a general rule of thumb, all network parameters should be unique to the network, but parameter collisions can still occur (unfortunately, this is the case with regtest and testnet3 sharing magics).