# Copyright 2019 Cameron Brown # Licensed under the Apache License, Version 2.0 (the 'License'); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # http://www.apache.org/licenses/LICENSE-2.0 # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an 'AS IS' BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. """A Source Engine .DEM file format is comprised of two parts, a header and a stream of 'frames'/events. Source: https://developer.valvesoftware.com/wiki/DEM_Format Types: Integer 4 bytes Float 4 bytes String 260 bytes Header: Type Field Value =========================================================================== String Header 8 characters, should be 'HL2DEMO'+NULL Int Demo Protocol Demo protocol version Int Network Protocol Network protocol version number String Server name 260 characters long String Client name 260 characters long String Map name 260 characters long String Game directory 260 characters long Float Playback time The length of the demo, in seconds Int Ticks Number of ticks in the demo Int Frames Number of frames in the demo (possibly) Int Sign on length Length of signon data (Init if first frame) Each frame begins with 0 or more of these commands. These are described in Source SDK code files. Frame (Network Protocols 7 and 8): Type Value Notes =========================================================================== dem_signon 1 Ignore. dem_packet 2 Ignore. dem_synctick 3 Ignore. dem_consolecmd 4 Read a standard data packet. dem_usercmd 5 Read a standard data packet. dem_datatables 6 Read a standard data packet. dem_stop 7 A signal that the demo is over. dem_lastcommand dem_stop Frame (Network Protocols 14 and 15): Type Value Notes =========================================================================== dem_stringtables 8 Read a standard data packet. dem_lastcommand dem_stringtables Frame (Network Protocols 36 and Higher): Type Value Notes =========================================================================== dem_customdata 8 n/a dem_stringtables 9 Read a standard data packet. dem_lastcommand dem_stringtables """ import struct from absl import app from absl import flags from absl import logging FLAGS = flags.FLAGS flags.DEFINE_string('file', None, 'Demo file to parse.') # First header field. Every demo must begin with this. HEADER = 'HL2DEMO\x00' # Default number of bytes for various data types. TYPE_INTEGER_LEN = 4 TYPE_FLOAT_LEN = 4 TYPE_STRING_LEN = 260 def __read_float(byte_arr, num_bytes=TYPE_FLOAT_LEN): """Reads a float from bytearray. Args: byte_arr (bytearray) Bytes to read float from. num_bytes (integer) Number of bytes to read. Source Engine has a default length of 4 bytes for float. Returns: buffer (string) The float that's been read. byte_arr (bytearray) The input bytearray with the read bytes trimmed off. """ buffer = struct.unpack('f', byte_arr[0:num_bytes])[0] return buffer, byte_arr[num_bytes:] def __read_int(byte_arr, num_bytes=TYPE_INTEGER_LEN): """Reads a integer from bytearray. Args: byte_arr (bytearray) Bytes to read integer from. num_bytes (integer) Number of bytes to read. Source Engine has a default length of 4 bytes for integer. Returns: buffer (string) The integer that's been read. byte_arr (bytearray) The input bytearray with the read bytes trimmed off. """ integer = int.from_bytes( byte_arr[0:num_bytes], byteorder='little', signed=False) return integer, byte_arr[num_bytes:] def __read_string(byte_arr, num_bytes=TYPE_STRING_LEN, strip=True): """Reads a string from bytearray. Args: byte_arr (bytearray) Bytes to read string from. num_bytes (integer) Number of bytes to read. Source Engine has a default length of 260 bytes, so that's what we're going with here. strip (boolean) Strip the null bytes. Returns: buffer (string) The string that's been read. byte_arr (bytearray) The input bytearray with the read bytes trimmed off. """ buffer = str(byte_arr[0:num_bytes], 'utf-8') if strip: buffer = buffer.replace('\x00', '') return buffer, byte_arr[num_bytes:] def parse_header(byte_arr): """Parse the demo's header. Args: byte_arr (bytearray) The byte array we're reading from. Returns: byte_arr (bytearray) Trimmed byte array without header. """ header = {} header['header'], byte_arr = __read_string(byte_arr, 8, False) # Check that the header field matches with the file format. if header['header'] != HEADER: raise Exception("Bad file format!") header['demo_protocol'], byte_arr = __read_int(byte_arr) header['network_protocol'], byte_arr = __read_int(byte_arr) header['server_name'], byte_arr = __read_string(byte_arr) header['client_name'], byte_arr = __read_string(byte_arr) header['map_name'], byte_arr = __read_string(byte_arr) header['game_directory'], byte_arr = __read_string(byte_arr) header['playback_time'], byte_arr = __read_float(byte_arr) header['total_ticks'], byte_arr = __read_int(byte_arr) header['total_frames'], byte_arr = __read_int(byte_arr) header['sign_on_length'], byte_arr = __read_int(byte_arr) header['tickrate'] = header['total_ticks'] / header['playback_time'] return header, byte_arr def parse_frame(byte_arr): """Parse a demo's frame. Args: byte_arr (bytearray) The byte array we're reading from. Returns: byte_arr (bytearray) Trimmed byte array without header. """ return None, byte_arr[4:] def parse_packet(byte_arr): """Parse a packet. Args: byte_arr (bytearray) The byte array we're reading from. Returns: byte_arr (bytearray) Trimmed byte array without header. """ length, byte_arr = __read_int(byte_arr) # Length of the data packet. print(length) return byte_arr[:length], byte_arr[length:] class Demo: """Represents a CS:GO demo.""" @staticmethod def from_bytes(byte_arr): """Create a Demo object from a raw file. Args: raw_file (bytearray) The raw contents of a demo. Returns: demo (Demo) The parsed demo object. """ if not isinstance(byte_arr, bytearray): raise Exception('File must be a bytearray type.') demo = Demo() header, byte_arr = parse_header(byte_arr) demo.header = header packet, byte_arr = parse_packet(byte_arr) # print(packet) # while len(byte_arr) > 0: # frame, byte_arr = parse_frame(byte_arr) # demo.frames.append(frame) # print(len(byte_arr)) return demo def __init__(self): self.header = {} self.frames = [] def main(argv): del argv # Unused. logging.info('Loading file %s.', FLAGS.file) if not FLAGS.file: print('You must provide a file!') return with open(FLAGS.file, 'rb') as f: output = bytearray(f.read()) logging.info('Parsing demo') demo = Demo.from_bytes(output) logging.info('Done!') if __name__ == '__main__': app.run(main)