Class: BTC::ScriptChunk

Inherits:
Object
  • Object
show all
Includes:
Opcodes
Defined in:
lib/btcruby/script/script_chunk.rb

Overview

ScriptChunk represents either an opcode or a pushdata command.

Constant Summary

Constants included from Opcodes

Opcodes::OPCODE_NAME_TO_VALUE, Opcodes::OPCODE_VALUE_TO_NAME, Opcodes::OP_0, Opcodes::OP_0NOTEQUAL, Opcodes::OP_1, Opcodes::OP_10, Opcodes::OP_11, Opcodes::OP_12, Opcodes::OP_13, Opcodes::OP_14, Opcodes::OP_15, Opcodes::OP_16, Opcodes::OP_1ADD, Opcodes::OP_1NEGATE, Opcodes::OP_1SUB, Opcodes::OP_2, Opcodes::OP_2DIV, Opcodes::OP_2DROP, Opcodes::OP_2DUP, Opcodes::OP_2MUL, Opcodes::OP_2OVER, Opcodes::OP_2ROT, Opcodes::OP_2SWAP, Opcodes::OP_3, Opcodes::OP_3DUP, Opcodes::OP_4, Opcodes::OP_5, Opcodes::OP_6, Opcodes::OP_7, Opcodes::OP_8, Opcodes::OP_9, Opcodes::OP_ABS, Opcodes::OP_ADD, Opcodes::OP_AND, Opcodes::OP_BOOLAND, Opcodes::OP_BOOLOR, Opcodes::OP_CAT, Opcodes::OP_CHECKLOCKTIMEVERIFY, Opcodes::OP_CHECKMULTISIG, Opcodes::OP_CHECKMULTISIGVERIFY, Opcodes::OP_CHECKSIG, Opcodes::OP_CHECKSIGVERIFY, Opcodes::OP_CODESEPARATOR, Opcodes::OP_DEPTH, Opcodes::OP_DIV, Opcodes::OP_DROP, Opcodes::OP_DUP, Opcodes::OP_ELSE, Opcodes::OP_ENDIF, Opcodes::OP_EQUAL, Opcodes::OP_EQUALVERIFY, Opcodes::OP_FALSE, Opcodes::OP_FROMALTSTACK, Opcodes::OP_GREATERTHAN, Opcodes::OP_GREATERTHANOREQUAL, Opcodes::OP_HASH160, Opcodes::OP_HASH256, Opcodes::OP_IF, Opcodes::OP_IFDUP, Opcodes::OP_INVALIDOPCODE, Opcodes::OP_INVERT, Opcodes::OP_LEFT, Opcodes::OP_LESSTHAN, Opcodes::OP_LESSTHANOREQUAL, Opcodes::OP_LSHIFT, Opcodes::OP_MAX, Opcodes::OP_MIN, Opcodes::OP_MOD, Opcodes::OP_MUL, Opcodes::OP_NEGATE, Opcodes::OP_NIP, Opcodes::OP_NOP, Opcodes::OP_NOP1, Opcodes::OP_NOP10, Opcodes::OP_NOP2, Opcodes::OP_NOP3, Opcodes::OP_NOP4, Opcodes::OP_NOP5, Opcodes::OP_NOP6, Opcodes::OP_NOP7, Opcodes::OP_NOP8, Opcodes::OP_NOP9, Opcodes::OP_NOT, Opcodes::OP_NOTIF, Opcodes::OP_NUMEQUAL, Opcodes::OP_NUMEQUALVERIFY, Opcodes::OP_NUMNOTEQUAL, Opcodes::OP_OR, Opcodes::OP_OVER, Opcodes::OP_PICK, Opcodes::OP_PUSHDATA1, Opcodes::OP_PUSHDATA2, Opcodes::OP_PUSHDATA4, Opcodes::OP_RESERVED, Opcodes::OP_RESERVED1, Opcodes::OP_RESERVED2, Opcodes::OP_RETURN, Opcodes::OP_RIGHT, Opcodes::OP_RIPEMD160, Opcodes::OP_ROLL, Opcodes::OP_ROT, Opcodes::OP_RSHIFT, Opcodes::OP_SHA1, Opcodes::OP_SHA256, Opcodes::OP_SIZE, Opcodes::OP_SUB, Opcodes::OP_SUBSTR, Opcodes::OP_SWAP, Opcodes::OP_TOALTSTACK, Opcodes::OP_TRUE, Opcodes::OP_TUCK, Opcodes::OP_VER, Opcodes::OP_VERIF, Opcodes::OP_VERIFY, Opcodes::OP_VERNOTIF, Opcodes::OP_WITHIN, Opcodes::OP_XOR

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(raw_data) ⇒ ScriptChunk 



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# File 'lib/btcruby/script/script_chunk.rb', line 199

def initialize(raw_data)
  @raw_data = raw_data
end

Instance Attribute Details

#opcode ⇒ Object (readonly)

Opcode for this chunk (first byte of the raw_data).



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# File 'lib/btcruby/script/script_chunk.rb', line 12

def opcode
  @opcode
end

#pushdata ⇒ Object (readonly)

If opcode is OP_PUSHDATA*, contains pure data being pushed. If opcode is OP_0, returns an empty string. If opcode is not pushdata, returns nil.



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# File 'lib/btcruby/script/script_chunk.rb', line 17

def pushdata
  @pushdata
end

#raw_data ⇒ Object (readonly)

Raw data for this chunk. 1 byte for regular opcode, 1 or more bytes for pushdata command. We do not call it ‘data’ to avoid confusion with pushdata (see below). The encoding is guaranteed to be binary.



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# File 'lib/btcruby/script/script_chunk.rb', line 9

def raw_data
  @raw_data
end

#size ⇒ Object (readonly)

Length of raw_data in bytes.



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# File 'lib/btcruby/script/script_chunk.rb', line 20

def size
  @size
end

Class Method Details

.with_data(data, offset: 0) ⇒ Object

Parses the chunk with binary data. Assumes the encoding is binary.

Raises:

  • (ArgumentError) 


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# File 'lib/btcruby/script/script_chunk.rb', line 143

def self.with_data(data, offset: 0)
  raise ArgumentError, "Data is missing" if !data

  opcode, _ = BTC::WireFormat.read_uint8(data: data, offset: offset)

  raise ArgumentError, "Failed to read opcode of the script chunk" if !opcode

  # push data opcode
  if opcode <= OP_PUSHDATA4

    length = data.bytesize

    if opcode < OP_PUSHDATA1
      pushdata_length = opcode
      chunk_length = 1 + pushdata_length
      if offset + chunk_length > length
        raise ArgumentError, "PUSHDATA is longer than we have bytes available"
      end
      return self.new(data[offset, chunk_length])
    elsif opcode == OP_PUSHDATA1
      pushdata_length, _ = BTC::WireFormat.read_uint8(data: data, offset: offset + 1)
      if !pushdata_length
        raise ArgumentError, "Failed to read length for PUSHDATA1"
      end
      chunk_length = 1 + 1 + pushdata_length
      if offset + chunk_length > length
        raise ArgumentError, "PUSHDATA1 is longer than we have bytes available"
      end
      return self.new(data[offset, chunk_length])
    elsif (opcode == OP_PUSHDATA2)
      pushdata_length, _ = BTC::WireFormat.read_uint16le(data: data, offset: offset + 1)
      if !pushdata_length
        raise ArgumentError, "Failed to read length for PUSHDATA2"
      end
      chunk_length = 1 + 2 + pushdata_length
      if offset + chunk_length > length
        raise ArgumentError, "PUSHDATA2 is longer than we have bytes available"
      end
      return self.new(data[offset, chunk_length])
    elsif (opcode == OP_PUSHDATA4)
      pushdata_length, _ = BTC::WireFormat.read_uint32le(data: data, offset: offset + 1)
      if !pushdata_length
        raise ArgumentError, "Failed to read length for PUSHDATA4"
      end
      chunk_length = 1 + 4 + pushdata_length
      if offset + chunk_length > length
        raise ArgumentError, "PUSHDATA4 is longer than we have bytes available"
      end
      return self.new(data[offset, chunk_length])
    end
  else
    # simple opcode - 1 byte
    return self.new(data[offset, 1])
  end
end

Instance Method Details

#==(other) ⇒ Object 



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# File 'lib/btcruby/script/script_chunk.rb', line 203

def ==(other)
  @raw_data == other.raw_data
end

#canonical? ⇒ Boolean

Returns true if this chunk is in canonical form (the most compact one). Returns false if it contains pushdata with too big length prefix. Example of non-canonical chunk: 75 bytes pushed with OP_PUSHDATA1 instead of simple 0x4b prefix. Note: this is not as strict as check_minimal_push in ScriptInterpreter.



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# File 'lib/btcruby/script/script_chunk.rb', line 44

def canonical?
  opcode = self.opcode
  if opcode < OP_PUSHDATA1
    return true # most compact pushdata is always canonical.
  elsif opcode == OP_PUSHDATA1
    return (self.raw_data.bytesize - (1+1)) >= OP_PUSHDATA1
  elsif opcode == OP_PUSHDATA2
    return (self.raw_data.bytesize - (1+2)) > 0xff
  elsif opcode == OP_PUSHDATA4
    return (self.raw_data.bytesize - (1+4)) > 0xffff
  else
    return true # all other opcodes are canonical (just 1 byte code)
  end
end

#data_only? ⇒ Boolean 



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# File 'lib/btcruby/script/script_chunk.rb', line 35

def data_only?
  opcode <= OP_16
end

#interpreted_data ⇒ Object

Returns corresponding data for data_only opcodes: pushdata or OP_N-encoded numbers. For all other opcodes returns nil.



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# File 'lib/btcruby/script/script_chunk.rb', line 82

def interpreted_data
  if d = pushdata
    return d
  end
  opcode = self.opcode
  if opcode == OP_1NEGATE || (opcode >= OP_1 && opcode <= OP_16)
    ScriptNumber.new(integer: opcode - OP_1 + 1).data
  else
    nil
  end
end

#length ⇒ Object

Length of raw_data in bytes.



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# File 'lib/btcruby/script/script_chunk.rb', line 21

def size
  @size
end

#opcode? ⇒ Boolean

Returns true if this is a non-pushdata (also not OP_0) opcode.



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# File 'lib/btcruby/script/script_chunk.rb', line 24

def opcode?
  !pushdata?
end

#pushdata? ⇒ Boolean

Returns true if this is a pushdata chunk (or OP_0 opcode).



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# File 'lib/btcruby/script/script_chunk.rb', line 29

def pushdata?
  # Compact pushdata opcodes are "virtual", just length prefixes.
  # Attention: OP_0 is also "pushdata" code that pushes empty data.
  opcode <= OP_PUSHDATA4
end

#to_s ⇒ Object 



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# File 'lib/btcruby/script/script_chunk.rb', line 98

def to_s
  opcode = self.opcode

  if self.opcode?
    return "OP_0"       if opcode == OP_0
    return "OP_1NEGATE" if opcode == OP_1NEGATE
    if opcode >= OP_1 && opcode <= OP_16
      return "OP_#{opcode + 1 - OP_1}"
    end
    return Opcode.name_for_opcode(opcode)
  end

  pushdata = self.pushdata
  return "OP_0" if pushdata.bytesize == 0 # Empty data is encoded as OP_0.

  string = ""

  # If it's some weird readable string, show it as a readable string.
  if data_is_ascii_printable?(pushdata) && (pushdata.bytesize < 20 || pushdata.bytesize > 65)
    string = pushdata.encode(Encoding::ASCII)
    # Escape escapes & single quote characters.
    string.gsub!("\\", "\\\\")
    string.gsub!("'", "\\'")
    # Wrap in single quotes. Why not double? Because they are already used in JSON and we don't want to multiply the mess.
    string = "'#{string}'"
  else
    string = BTC.to_hex(pushdata)
    # Shorter than 128-bit chunks are wrapped in square brackets to avoid ambiguity with big all-decimal numbers.
    if (pushdata.bytesize < 16)
        string = "[#{string}]"
    end
  end

  # Pushdata with non-compact encoding will have explicit length prefix (1 for OP_PUSHDATA1, 2 for OP_PUSHDATA2 and 4 for OP_PUSHDATA4).
  if !canonical?
    prefix = 1
    prefix = 2 if opcode == OP_PUSHDATA2
    prefix = 4 if opcode == OP_PUSHDATA4
    string = "#{prefix}:#{string}"
  end

  return string
end