scriptbuilder

Documentation

Index

• Constants
• Variables
• func CanonicalDataSize(data []byte) int
• type ScriptBuilder
  • func NewScriptBuilder() *ScriptBuilder
  • func (b *ScriptBuilder) AddData(data []byte) *ScriptBuilder
  • func (b *ScriptBuilder) AddFullData(data []byte) *ScriptBuilder
  • func (b *ScriptBuilder) AddInt64(val int64) *ScriptBuilder
  • func (b *ScriptBuilder) AddOp(opcode byte) *ScriptBuilder
  • func (b *ScriptBuilder) AddOps(opcodes []byte) *ScriptBuilder
  • func (b *ScriptBuilder) Reset() *ScriptBuilder
  • func (b *ScriptBuilder) Script() ([]byte, er.R)

Constants

const (
	// DefaultScriptAlloc is the default size used for the backing array
	// for a script being built by the ScriptBuilder.  The array will
	// dynamically grow as needed, but this figure is intended to provide
	// enough space for vast majority of scripts without needing to grow the
	// backing array multiple times.
	DefaultScriptAlloc = 500
)

Variables

var ErrScriptNotCanonical = txscripterr.Err.Code("ErrScriptNotCanonical")

ErrScriptNotCanonical identifies a non-canonical script. The caller can use a type assertion to detect this error type.

Functions

func CanonicalDataSize

func CanonicalDataSize(data []byte) int

CanonicalDataSize returns the number of bytes the canonical encoding of the data will take.

Types

type ScriptBuilder

type ScriptBuilder struct {
	ScriptInt []byte
	ErrInt    er.R
}

ScriptBuilder provides a facility for building custom scripts. It allows you to push opcodes, ints, and data while respecting canonical encoding. In general it does not ensure the script will execute correctly, however any data pushes which would exceed the maximum allowed script engine limits and are therefore guaranteed not to execute will not be pushed and will result in the Script function returning an error.

For example, the following would build a 2-of-3 multisig script for usage in a pay-to-script-hash (although in this situation MultiSigScript() would be a better choice to generate the script):

builder := scriptbuilder.NewScriptBuilder()
builder.AddOp(opcode.OP_2).AddData(pubKey1).AddData(pubKey2)
builder.AddData(pubKey3).AddOp(opcode.OP_3)
builder.AddOp(opcode.OP_CHECKMULTISIG)
script, err := builder.Script()
if err != nil {
	// Handle the error.
	return
}
fmt.Printf("Final multi-sig script: %x\n", script)

func NewScriptBuilder

func NewScriptBuilder() *ScriptBuilder

NewScriptBuilder returns a new instance of a script builder. See ScriptBuilder for details.

func (*ScriptBuilder) AddData

func (b *ScriptBuilder) AddData(data []byte) *ScriptBuilder

AddData pushes the passed data to the end of the script. It automatically chooses canonical opcodes depending on the length of the data. A zero length buffer will lead to a push of empty data onto the stack (OP_0) and any push of data greater than MaxScriptElementSize will not modify the script since that is not allowed by the script engine. Also, the script will not be modified if pushing the data would cause the script to exceed the maximum allowed script engine size.

func (*ScriptBuilder) AddFullData

func (b *ScriptBuilder) AddFullData(data []byte) *ScriptBuilder

AddFullData should not typically be used by ordinary users as it does not include the checks which prevent data pushes larger than the maximum allowed sizes which leads to scripts that can't be executed. This is provided for testing purposes such as regression tests where sizes are intentionally made larger than allowed.

Use AddData instead.

func (*ScriptBuilder) AddInt64

func (b *ScriptBuilder) AddInt64(val int64) *ScriptBuilder

AddInt64 pushes the passed integer to the end of the script. The script will not be modified if pushing the data would cause the script to exceed the maximum allowed script engine size.

func (*ScriptBuilder) AddOp

func (b *ScriptBuilder) AddOp(opcode byte) *ScriptBuilder

AddOp pushes the passed opcode to the end of the script. The script will not be modified if pushing the opcode would cause the script to exceed the maximum allowed script engine size.

func (*ScriptBuilder) AddOps

func (b *ScriptBuilder) AddOps(opcodes []byte) *ScriptBuilder

AddOps pushes the passed opcodes to the end of the script. The script will not be modified if pushing the opcodes would cause the script to exceed the maximum allowed script engine size.

func (*ScriptBuilder) Reset

func (b *ScriptBuilder) Reset() *ScriptBuilder

Reset resets the script so it has no content.

func (*ScriptBuilder) Script

func (b *ScriptBuilder) Script() ([]byte, er.R)

Script returns the currently built script. When any errors occurred while building the script, the script will be returned up the point of the first error along with the error.