lib/coinbasetx.py

   1 import binascii
   2 import halfnode
   3 import struct
   4 import util
   5
   6 class CoinbaseTransaction(halfnode.CTransaction):
   7     '''Construct special transaction used for coinbase tx.
   8     It also implements quick serialization using pre-cached
   9     scriptSig template.'''
  10
  11     extranonce_type = '>Q'
  12     extranonce_placeholder = struct.pack(extranonce_type, int('f000000ff111111f', 16))
  13     extranonce_size = struct.calcsize(extranonce_type)
  14
  15     def __init__(self, timestamper, coinbaser, value, flags, height, data):
  16         super(CoinbaseTransaction, self).__init__()
  17
  18         #self.extranonce = 0
  19
  20         if len(self.extranonce_placeholder) != self.extranonce_size:
  21             raise Exception("Extranonce placeholder don't match expected length!")
  22
  23         tx_in = halfnode.CTxIn()
  24         tx_in.prevout.hash = 0L
  25         tx_in.prevout.n = 2**32-1
  26         tx_in._scriptSig_template = (
  27             util.ser_number(height) + binascii.unhexlify(flags) + util.ser_number(int(timestamper.time())) + \
  28             chr(self.extranonce_size),
  29             util.ser_string(coinbaser.get_coinbase_data() + data)
  30         )
  31
  32         tx_in.scriptSig = tx_in._scriptSig_template[0] + self.extranonce_placeholder + tx_in._scriptSig_template[1]
  33
  34         tx_out = halfnode.CTxOut()
  35         tx_out.nValue = value
  36         tx_out.scriptPubKey = coinbaser.get_script_pubkey()
  37
  38         self.vin.append(tx_in)
  39         self.vout.append(tx_out)
  40
  41         # Two parts of serialized coinbase, just put part1 + extranonce + part2 to have final serialized tx
  42         self._serialized = super(CoinbaseTransaction, self).serialize().split(self.extranonce_placeholder)
  43
  44     def set_extranonce(self, extranonce):
  45         if len(extranonce) != self.extranonce_size:
  46             raise Exception("Incorrect extranonce size")
  47
  48         (part1, part2) = self.vin[0]._scriptSig_template
  49         self.vin[0].scriptSig = part1 + extranonce + part2