Class: Bitcoin::Tx

Inherits:
Object show all
Defined in:
lib/bitcoin/tx.rb

Overview

Transaction class

Constant Summary collapse

MAX_STANDARD_VERSION = 
2
MAX_STANDARD_TX_WEIGHT =

The maximum weight for transactions we’re willing to relay/mine

400000
MARKER = 
0x00
FLAG = 
0x01

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Tx

Returns a new instance of Tx.



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# File 'lib/bitcoin/tx.rb', line 24

def initialize
  @inputs = []
  @outputs = []
  @version = 1
  @lock_time = 0
end

Instance Attribute Details

#flag ⇒ Object

Returns the value of attribute flag.



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# File 'lib/bitcoin/tx.rb', line 19

def flag
  @flag
end

#inputs ⇒ Object (readonly) Also known as: in

Returns the value of attribute inputs.



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# File 'lib/bitcoin/tx.rb', line 20

def inputs
  @inputs
end

#lock_time ⇒ Object

Returns the value of attribute lock_time.



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# File 'lib/bitcoin/tx.rb', line 22

def lock_time
  @lock_time
end

#marker ⇒ Object

Returns the value of attribute marker.



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# File 'lib/bitcoin/tx.rb', line 18

def marker
  @marker
end

#outputs ⇒ Object (readonly) Also known as: out

Returns the value of attribute outputs.



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# File 'lib/bitcoin/tx.rb', line 21

def outputs
  @outputs
end

#version ⇒ Object

Returns the value of attribute version.



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# File 'lib/bitcoin/tx.rb', line 17

def version
  @version
end

Class Method Details

.parse_from_payload(payload) ⇒ Object 



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# File 'lib/bitcoin/tx.rb', line 34

def self.parse_from_payload(payload)
  buf = payload.is_a?(String) ? StringIO.new(payload) : payload
  tx = new
  tx.version = buf.read(4).unpack('V').first

  in_count = Bitcoin.unpack_var_int_from_io(buf)
  witness = false
  if in_count.zero?
    tx.marker = 0
    tx.flag = buf.read(1).unpack('c').first
    if tx.flag.zero?
      buf.pos -= 1
    else
      in_count = Bitcoin.unpack_var_int_from_io(buf)
      witness = true
    end
  end

  in_count.times do
    tx.inputs << TxIn.parse_from_payload(buf)
  end

  out_count = Bitcoin.unpack_var_int_from_io(buf)
  out_count.times do
    tx.outputs << TxOut.parse_from_payload(buf)
  end

  if witness
    in_count.times do |i|
      tx.inputs[i].script_witness = Bitcoin::ScriptWitness.parse_from_payload(buf)
    end
  end

  tx.lock_time = buf.read(4).unpack('V').first

  tx
end

Instance Method Details

#==(other) ⇒ Object 



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# File 'lib/bitcoin/tx.rb', line 111

def ==(other)
  hash == other.hash
end

#coinbase_tx? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/bitcoin/tx.rb', line 103

def coinbase_tx?
  inputs.length == 1 && inputs.first.coinbase?
end

#hash ⇒ Object 



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# File 'lib/bitcoin/tx.rb', line 72

def hash
  Bitcoin.double_sha256(serialize_old_format).bth
end

#serialize_old_format ⇒ Object

serialize tx with old tx format



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# File 'lib/bitcoin/tx.rb', line 116

def serialize_old_format
  buf = [version].pack('V')
  buf << Bitcoin.pack_var_int(inputs.length) << inputs.map(&:to_payload).join
  buf << Bitcoin.pack_var_int(outputs.length) << outputs.map(&:to_payload).join
  buf << [lock_time].pack('V')
  buf
end

#serialize_witness_format ⇒ Object

serialize tx with segwit tx format github.com/bitcoin/bips/blob/master/bip-0144.mediawiki



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# File 'lib/bitcoin/tx.rb', line 126

def serialize_witness_format
  buf = [version, MARKER, FLAG].pack('Vcc')
  buf << Bitcoin.pack_var_int(inputs.length) << inputs.map(&:to_payload).join
  buf << Bitcoin.pack_var_int(outputs.length) << outputs.map(&:to_payload).join
  buf << witness_payload << [lock_time].pack('V')
  buf
end

#sighash_for_input(input_index, output_script, hash_type: , sig_version: :base, amount: nil, skip_separator_index: 0) ⇒ Object

get signature hash the script code needs is the witnessScript but removing everything up to and including the last executed OP_CODESEPARATOR before the signature checking opcode being executed.

Parameters:

  • input_index (Integer) —

    input index.

  • hash_type (Integer) (defaults to: ) —

    signature hash type

  • output_script (Bitcoin::Script) —

    script pubkey or script code. if script pubkey is P2WSH, set witness script to this.

  • amount (Integer) (defaults to: nil) —

    bitcoin amount locked in input. required for witness input only.

  • skip_separator_index (Integer) (defaults to: 0) —

    If output_script is P2WSH and output_script contains any OP_CODESEPARATOR,

Raises:

  • (ArgumentError) 


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# File 'lib/bitcoin/tx.rb', line 188

def sighash_for_input(input_index, output_script, hash_type: SIGHASH_TYPE[:all],
                      sig_version: :base, amount: nil, skip_separator_index: 0)
  raise ArgumentError, 'input_index must be specified.' unless input_index
  raise ArgumentError, 'does not exist input corresponding to input_index.' if input_index >= inputs.size
  raise ArgumentError, 'script_pubkey must be specified.' unless output_script
  raise ArgumentError, 'unsupported sig version specified.' unless SIG_VERSION.include?(sig_version)

  if sig_version == :witness_v0 || Bitcoin.chain_params.fork_chain?
    raise ArgumentError, 'amount must be specified.' unless amount
    sighash_for_witness(input_index, output_script, hash_type, amount, skip_separator_index)
  else
    sighash_for_legacy(input_index, output_script, hash_type)
  end
end

#size ⇒ Object

The serialized transaction size



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# File 'lib/bitcoin/tx.rb', line 162

def size
  to_payload.bytesize
end

#standard? ⇒ Boolean

check this tx is standard.

Returns:

  • (Boolean) 


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# File 'lib/bitcoin/tx.rb', line 139

def standard?
  return false if version > MAX_STANDARD_VERSION
  return false if weight > MAX_STANDARD_TX_WEIGHT
  inputs.each do |i|
    # Biggest 'standard' txin is a 15-of-15 P2SH multisig with compressed keys (remember the 520 byte limit on redeemScript size).
    # That works out to a (15*(33+1))+3=513 byte redeemScript, 513+1+15*(73+1)+3=1627
    # bytes of scriptSig, which we round off to 1650 bytes for some minor future-proofing.
    # That's also enough to spend a 20-of-20 CHECKMULTISIG scriptPubKey, though such a scriptPubKey is not considered standard.
    return false if i.script_sig.size > 1650
    return false unless i.script_sig.push_only?
  end
  data_count = 0
  outputs.each do |o|
    return false unless o.script_pubkey.standard?
    data_count += 1 if o.script_pubkey.op_return?
    # TODO add non P2SH multisig relay(permitbaremultisig)
    # TODO add dust relay check
  end
  return false if data_count > 1
  true
end

#to_h ⇒ Object 



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# File 'lib/bitcoin/tx.rb', line 225

def to_h
  {
      txid: txid, hash: witness_hash.rhex, version: version, size: size, vsize: vsize, locktime: lock_time,
      vin: inputs.map(&:to_h), vout: outputs.map.with_index{|tx_out, index| tx_out.to_h.merge({n: index})}
  }
end

#to_payload ⇒ Object 



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# File 'lib/bitcoin/tx.rb', line 99

def to_payload
  witness? ? serialize_witness_format : serialize_old_format
end

#txid ⇒ Object 



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# File 'lib/bitcoin/tx.rb', line 76

def txid
  hash.rhex
end

#verify_input_sig(input_index, script_pubkey, amount: nil, flags: STANDARD_SCRIPT_VERIFY_FLAGS) ⇒ Object

verify input signature.

Parameters:

  • input_index (Integer)
  • script_pubkey (Bitcoin::Script) —

    the script pubkey for target input.

  • amount (Integer) (defaults to: nil) —

    the amount of bitcoin, require for witness program only.

  • flags (Array) (defaults to: STANDARD_SCRIPT_VERIFY_FLAGS) —

    the flags used when execute script interpreter.



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# File 'lib/bitcoin/tx.rb', line 208

def verify_input_sig(input_index, script_pubkey, amount: nil, flags: STANDARD_SCRIPT_VERIFY_FLAGS)
  script_sig = inputs[input_index].script_sig
  has_witness = inputs[input_index].has_witness?

  if script_pubkey.p2sh?
    flags << SCRIPT_VERIFY_P2SH
    redeem_script = Script.parse_from_payload(script_sig.chunks.last)
    script_pubkey = redeem_script if redeem_script.p2wpkh?
  end

  if has_witness || Bitcoin.chain_params.fork_chain?
    verify_input_sig_for_witness(input_index, script_pubkey, amount, flags)
  else
    verify_input_sig_for_legacy(input_index, script_pubkey, flags)
  end
end

#vsize ⇒ Object

The virtual transaction size (differs from size for witness transactions)



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# File 'lib/bitcoin/tx.rb', line 167

def vsize
  (weight.to_f / 4).ceil
end

#weight ⇒ Object

calculate tx weight weight = (legacy tx payload) * 3 + (witness tx payload)



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# File 'lib/bitcoin/tx.rb', line 173

def weight
  if witness?
    serialize_old_format.bytesize * (WITNESS_SCALE_FACTOR - 1) + serialize_witness_format.bytesize
  else
    serialize_old_format.bytesize * WITNESS_SCALE_FACTOR
  end
end

#witness? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/bitcoin/tx.rb', line 107

def witness?
  !inputs.find { |i| !i.script_witness.empty? }.nil?
end

#witness_commitment ⇒ Object

get the witness commitment of coinbase tx. if this tx does not coinbase or not have commitment, return nil.



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# File 'lib/bitcoin/tx.rb', line 90

def witness_commitment
  return nil unless coinbase_tx?
  outputs.each do |output|
    commitment = output.script_pubkey.witness_commitment
    return commitment if commitment
  end
  nil
end

#witness_hash ⇒ Object 



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# File 'lib/bitcoin/tx.rb', line 80

def witness_hash
  Bitcoin.double_sha256(to_payload).bth
end

#witness_payload ⇒ Object 



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# File 'lib/bitcoin/tx.rb', line 134

def witness_payload
  inputs.map { |i| i.script_witness.to_payload }.join
end

#wtxid ⇒ Object 



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# File 'lib/bitcoin/tx.rb', line 84

def wtxid
  witness_hash.rhex
end