Class: Bitcoin::Builder::TxBuilder

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

Overview

DSL to create Bitcoin::Protocol::Tx used by Builder#build_tx.

tx = tx do |t|
  t.input do |i|
    i.prev_out prev_tx  # previous transaction
    i.prev_out_index 0  # index of previous output
    i.signature_key key # Bitcoin::Key used to sign the input
  end
  t.output do |o|
    o.value 12345 # 0.00012345 BTC
    o.script {|s| s.type :address; s.recipient key.addr }
  end
end

signs every input that has a signature key. if the signature key is not specified, the input will include the #sig_hash that needs to be signed.

Instance Method Summary collapse

Constructor Details

#initialize ⇒ TxBuilder

Returns a new instance of TxBuilder.



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

def initialize
  @tx = P::Tx.new(nil)
  @tx.ver, @tx.lock_time = 1, 0
  @ins, @outs = [], []
end

Instance Method Details

#input {|c| ... } ⇒ Object

add an input to the transaction (see TxInBuilder).

Yields:

  • (c) 


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# File 'lib/bitcoin/builder.rb', line 151

def input
  c = TxInBuilder.new
  yield c
  @ins << c
end

#lock_time(n) ⇒ Object

specify tx lock_time. this is usually not necessary. defaults to 0.



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# File 'lib/bitcoin/builder.rb', line 146

def lock_time n
  @tx.lock_time = n
end

#output {|c| ... } ⇒ Object

add an output to the transaction (see TxOutBuilder).

Yields:

  • (c) 


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# File 'lib/bitcoin/builder.rb', line 158

def output
  c = TxOutBuilder.new
  yield c
  @outs << c
end

#tx ⇒ Object

create the transaction according to values specified via DSL. sign each input that has a signature key specified. if there is no key, store the sig_hash in the input, so it can easily be signed later.



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# File 'lib/bitcoin/builder.rb', line 168

def tx
  @ins.each {|i| @tx.add_in(i.txin) }
  @outs.each {|o| @tx.add_out(o.txout) }
  @ins.each_with_index do |inc, i|
    if @tx.in[i].coinbase?
      script_sig = [inc.coinbase_data].pack("H*")
      @tx.in[i].script_sig_length = script_sig.bytesize
      @tx.in[i].script_sig = script_sig
      next
    end
    prev_tx = inc.instance_variable_get(:@prev_out)
    @sig_hash = @tx.signature_hash_for_input(i, prev_tx)
    if inc.key && inc.key.priv
      sig = inc.key.sign(@sig_hash)
      script_sig = Script.to_signature_pubkey_script(sig, [inc.key.pub].pack("H*"))
      @tx.in[i].script_sig_length = script_sig.bytesize
      @tx.in[i].script_sig = script_sig
      raise "Signature error"  unless @tx.verify_input_signature(i, prev_tx)
    else
      @tx.in[i].script_sig_length = 0
      @tx.in[i].script_sig = ""
      @tx.in[i].sig_hash = @sig_hash
      @tx.in[i].sig_address = Script.new(prev_tx.out[@tx.in[i].prev_out_index].pk_script).get_address
    end
  end
  data = @tx.in.map {|i| [i.sig_hash, i.sig_address] }
  tx = P::Tx.new(@tx.to_payload)
  data.each.with_index {|d, i| i = tx.in[i]; i.sig_hash = d[0]; i.sig_address = d[1] }
  raise "Payload Error"  unless tx.to_payload == @tx.to_payload
  tx
end

#version(n) ⇒ Object

specify tx version. this is usually not necessary. defaults to 1.



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# File 'lib/bitcoin/builder.rb', line 141

def version n
  @tx.ver = n
end