import struct from typing import Optional, List, Dict, Any from typing_extensions import Final from bemani.protocol.stream import InputStream, OutputStream from bemani.protocol.node import Node class BinaryEncodingException(Exception): """ Generic exception to be thrown when we encounter an issue decoding a binary stream """ class PackedOrdering: """ A class that helps us encapsulate Konami's batshit backtracking hole-fill algorithm. Everything is aligned on a boundary appropriate for its data size. Strings and arrays are forced to be aligned to a 4 byte boundary on account of having an integer length field. All of these are padded to 4 bytes in terms of the room they take up in the stream. For the things that are 2 byte or 1 byte aligned, we end up sticking them after each other in 4 byte increments. That is, to say, if we have a unsigned byte to pack, we reserve 4 bytes and stick it in the first byte slot, and if up to three additional bytes come in we will pack them after this in sequential order. It would make sense to not pad out strings and arrays and store bytes/shorts in these unused locations, but that's not what actually happens. Also note that we will never pack bytes after a short or vice versa, even if there is room. This also explains the bizarre behavior of not using spare bytes after strings or arrays. I'll emphasize again: everything is stored aligned, and in a 4 byte chunk, only similarly-sized objects can be packed. If this 4 byte chunk is already partially occupied, we can only add another thing to it if 1) the item being added is the same size as the object that exists and 2) the object can be added with the correct alignment. A simple example: [1: byte] [2: byte] [3: integer] Packing would look like this (assuming all locations are a byte): 1 2 0 0 3 3 3 3 An example: [1: byte] [2: string, length 3] [3: short] [4: byte] Packing would look like this (assuming all locations are a byte): 1 4 0 0 2 2 2 2 2 2 2 0 3 3 0 0 """ def __init__(self, size: int, allow_expansion: bool=False) -> None: """ Initialize with a known size. If this is to be used to create a packing instead of deduce a packing, then allow_expansion should be set to true and new holes will be created when needed. If this is to be used for decoding a current packing, allow_expansion should be set to False to ensure we don't choose locations outside the buffer. Parameters: size - Number of bytes to work with as an integer allow_expansion - Boolean describing whether to add to the end of the order when needed """ self.order: List[Optional[int]] = [] self.expand = allow_expansion for _ in range(size): self.order.append(None) self.__orderlen = size self.__lastbyte = 0 self.__lastshort = 0 self.__lastint = 0 def __append_empty(self) -> None: self.order.append(None) self.__orderlen = self.__orderlen + 1 def mark_used(self, size: int, offset: int, round_to: int=1) -> None: """ Mark size bytes at offset as being used. If needed, round to the nearest byte/half/integer. Parameters: size - Number of bytes to mark offset - Offset into binary chunk to start marking round_to - Optional integer specifying how many bytes to round to. Valid values are 1, 2 and 4 """ # Round to nearest value if needed while (size & (round_to - 1)) != 0: size = size + 1 # Expand buffer if needed if self.expand: while self.__orderlen < (size + offset): self.__append_empty() # Mark buffer as used for i in range(size): self.order[i + offset] = size def get_next_byte(self) -> Optional[int]: """ Returns an integer location where the next byte will be found/stored, respecting Konami logic. Will return None if its not possible to find this integer a spot and we aren't expanding. """ # If we expand for additions, make sure we've padded to a 4 byte boundary if self.expand: while (self.__orderlen & 3) != 0: self.__append_empty() for i in range(self.__lastbyte, self.__orderlen, 4): if self.order[i] is not None: # See if this has room for a byte for j in range(0, 4): if self.order[i + j] == 1: # This is okay, we can pack after this continue elif self.order[i + j] is None: # This is open, pack here self.__lastbyte = i return i + j else: # This is something else, can't pack here break else: # Couldn't find optimal packing, pack here self.__lastbyte = i return i if self.expand: self.__lastbyte = self.__orderlen return self.__orderlen else: return None def get_next_short(self) -> Optional[int]: """ Returns an integer location where the next short will be found/stored, respecting Konami logic. Will return None if its not possible to find this integer a spot and we aren't expanding. """ # If we expand for additions, make sure we've padded to a 4 byte boundary if self.expand: while (self.__orderlen & 3) != 0: self.__append_empty() for i in range(self.__lastshort, self.__orderlen, 4): if self.order[i] is not None: for j in range(0, 4, 2): if self.order[i + j] == 2 and self.order[i + j + 1] == 2: # This is okay, we can pack after this continue elif self.order[i + j] is None and self.order[i + j + 1] is None: # This is open, pack here self.__lastshort = i return i + j else: # This is something else, can't pack here break else: # Couldn't find optimal packing, pack here self.__lastshort = i return i if self.expand: self.__lastshort = self.__orderlen return self.__orderlen else: return None def get_next_int(self) -> Optional[int]: """ Returns an integer location where the next integer will be found/stored, respecting Konami logic. Will return None if its not possible to find this integer a spot and we aren't expanding. """ # If we expand for additions, make sure we've padded to a 4 byte boundary if self.expand: while (self.__orderlen & 3) != 0: self.__append_empty() for i in range(self.__lastint, self.__orderlen, 4): if self.order[i] is not None: continue if self.order[i + 1] is not None: continue if self.order[i + 2] is not None: continue if self.order[i + 3] is not None: continue self.__lastint = i return i if self.expand: self.__lastint = self.__orderlen return self.__orderlen else: return None @staticmethod def node_to_body_ordering(node: Node, include_children: bool=True, include_void: bool=False) -> List[Dict[str, Any]]: """ Walk this node, attributes and children in the correct order to create a node ordering for the purpose of mapping Node objects to their actual data in a binary packet data chunk. We will use this to unpack data to determine the values of nodes, or to create the data that goes with these nodes. Paramters: include_children - Whether this ordering should include children. Defaults to True. include_void - Whether this ordering should include positions for void nodes. Defaults to false. Returns: List of dictionary objects: - type - 'attribute' or 'value' to specify that this position in the node walk is a string attribute or a node value - node - This Node object, for the purpose of assignment - name - The name of the attribute if type is 'attribute' or the name of the node if type is 'value' - alignment - The alignment that this particular data object requiers """ ordering = [] # Include the node itself if it has a value or we include voids if node.data_length != 0 or include_void: alignment = node.data_length if alignment is None: # Take care of string types alignment = 4 if alignment > 4: # Take care of 64 bit integers that are 32 bit aligned alignment = 4 ordering.append({ 'type': 'value', 'node': node, 'name': node.name, 'alignment': alignment, }) order = sorted(node.attributes.keys()) for attr in order: ordering.append({ 'type': 'attribute', 'node': node, 'name': attr, 'alignment': 4, }) if include_children: for child in node.children: ordering.extend(PackedOrdering.node_to_body_ordering(child)) return ordering class BinaryDecoder: """ A class capable of taking a binary blob and decoding it to a Node tree. """ def __init__(self, data: bytes, encoding: str) -> None: """ Initialize the object. Parameters: - data - A binary blob of data to be decoded - encoding - A string representing the text encoding for string elements. Should be either 'shift-jis', 'euc-jp' or 'utf-8' """ self.stream = InputStream(data) self.encoding = encoding self.executed = False def __read_node_name(self) -> str: """ Given the current position in the stream, read the 6-bit-byte packed string name of the node. Returns: A string representing the name in ascii """ length = self.stream.read_int() if length is None: raise BinaryEncodingException("Ran out of data when attempting to read node name length!") binary_length = int(((length * 6) + 7) / 8) def int_to_bin(integer: int) -> str: val = bin(integer)[2:] while len(val) < 8: val = '0' + val return val data = '' for _ in range(binary_length): next_byte = self.stream.read_int() if next_byte is None: raise BinaryEncodingException("Ran out of data when attempting to read node name!") data = data + int_to_bin(next_byte) data_str = [data[i:(i + 6)] for i in range(0, len(data), 6)] data_int = [int(val, 2) for val in data_str] ret = ''.join([Node.NODE_NAME_CHARS[val] for val in data_int]) ret = ret[:length] return ret def __read_node(self, node_type: int) -> Node: """ Given an integer node type, read the node's name, possible attributes and children. Will return a Node representing this node. Note that calling this on the first node should return a tree of all nodes. Returns: Node object """ name = self.__read_node_name() node = Node(name=name, type=node_type) while True: child_type = self.stream.read_int() if child_type is None: raise BinaryEncodingException("Ran out of data when attempting to read node type!") if child_type == Node.END_OF_NODE: return node elif child_type == Node.ATTR_TYPE: key = self.__read_node_name() node.set_attribute(key) else: child = self.__read_node(child_type) node.add_child(child) def get_tree(self) -> Node: """ Parse the header and body such that we can return a Node tree representing the data passed to us. Returns: Node object """ if self.executed: raise BinaryEncodingException("Logic error, should only call this once per instance") self.executed = True # Read the header first header_length = self.stream.read_int(4) if header_length is None: raise BinaryEncodingException("Ran out of data when attempting to read header length!") node_type = self.stream.read_int() if node_type is None: raise BinaryEncodingException("Ran out of data when attempting to read root node type!") root = self.__read_node(node_type) eod = self.stream.read_int() if eod != Node.END_OF_DOCUMENT: raise BinaryEncodingException(f'Unknown node type {eod} at end of document') # Skip by any padding while self.stream.pos < header_length + 4: self.stream.read_byte() # Read the body next body_length = self.stream.read_int(4) if body_length is not None and body_length > 0: # We have a body body = self.stream.read_blob(body_length) if body is None: raise BinaryEncodingException('Body has insufficient data') ordering = PackedOrdering(body_length) values = PackedOrdering.node_to_body_ordering(root) for value in values: node = value['node'] if value['type'] == 'attribute': size = None enc = 's' dtype = 'str' array = False composite = False else: size = node.data_length enc = node.data_encoding dtype = node.data_type array = node.is_array composite = node.is_composite if composite and array: raise Exception('Logic error, no support for composite arrays!') if not array: # Scalar value alignment = value['alignment'] if alignment == 1: loc = ordering.get_next_byte() elif alignment == 2: loc = ordering.get_next_short() elif alignment == 4: loc = ordering.get_next_int() if loc is None: raise BinaryEncodingException("Ran out of data when attempting to read node data location!") if size is None: # The size should be read from the first 4 bytes size = struct.unpack('>I', body[loc:(loc + 4)])[0] ordering.mark_used(size + 4, loc, round_to=4) loc = loc + 4 decode_data = body[loc:(loc + size)] decode_value = f'>{size}{enc}' else: # The size is built-in ordering.mark_used(size, loc) decode_data = body[loc:(loc + size)] decode_value = f'>{enc}' if composite: val_list = list(struct.unpack(decode_value, decode_data)) if value['type'] == 'attribute': raise Exception('Logic error, shouldn\'t have composite attribute type!') node.set_value(val_list) continue val = struct.unpack(decode_value, decode_data)[0] if dtype == 'str': # Need to convert this from encoding to standard string. # Also, need to lob off the trailing null. try: val = val[:-1].decode(self.encoding) except UnicodeDecodeError: # Nothing we can do here pass if value['type'] == 'attribute': node.set_attribute(value['name'], val) else: node.set_value(val) else: # Array value loc = ordering.get_next_int() if loc is None: raise BinaryEncodingException("Ran out of data when attempting to read array length location!") # The raw size in bytes length = struct.unpack('>I', body[loc:(loc + 4)])[0] elems = int(length / size) ordering.mark_used(length + 4, loc, round_to=4) loc = loc + 4 decode_data = body[loc:(loc + length)] decode_value = f'>{enc * elems}' val = struct.unpack(decode_value, decode_data) node.set_value([v for v in val]) return root class BinaryEncoder: """ A class capable of taking a Node tree and encoding it into a binary format. """ def __init__(self, tree: Node, encoding: str) -> None: """ Initialize the object. Parameters: tree - A binary blob of data to be decoded encoding - A string representing the text encoding for string elements. Should be either 'shift-jis', 'euc-jp' or 'utf-8' """ self.stream = OutputStream() self.encoding = encoding self.tree = tree self.__body: List[int] = [] self.__body_len = 0 self.executed = False # Generate the characer LUT self.char_lut: Dict[str, int] = {} for i in range(len(Node.NODE_NAME_CHARS)): self.char_lut[Node.NODE_NAME_CHARS[i]] = i def __write_node_name(self, name: str) -> None: """ Given the current position in the stream, write the 6-bit-byte packed string name of the node. Parameters: name - A string name which should be encoded as a node name """ def char_to_bin(ch: str) -> str: index = self.char_lut[ch] val = bin(index)[2:] while len(val) < 6: val = '0' + val return val[-6:] # Convert to six bit bytes length = len(name) data = ''.join([char_to_bin(c) for c in name]) # Pad out the rest with zeros while (len(data) & 0x7) != 0: data = data + '0' # Convert to 8-bit bytes data_chunks = [data[i:(i + 8)] for i in range(0, len(data), 8)] data_int = [int(val, 2) for val in data_chunks] # Output self.stream.write_int(length) for val in data_int: self.stream.write_int(val) def __write_node(self, node: Node) -> None: """ Given an integer node type, read the node's name, possible attributes and children. Will return a Node representing this node. Note that calling this on the first node should return a tree of all nodes. Parameters: node - A Node which should be encoded. """ to_write = PackedOrdering.node_to_body_ordering(node, include_children=False, include_void=True) for thing in to_write: # First, write the type of this node out if thing['type'] == 'value': self.stream.write_int(thing['node'].type) else: self.stream.write_int(Node.ATTR_TYPE) # Now, write the name out self.__write_node_name(thing['name']) # Now, write out the children for child in node.children: self.__write_node(child) # Now, write out the end of node marker self.stream.write_int(Node.END_OF_NODE) def __add_data(self, data: bytes, length: int, offset: int) -> None: """ Given some binary data, a length and an offset, add the data to the offset in the output body. This function will ensure that any new bytes that aren't copied are zero'd out. This includes bytes before the offset as well as any pad bytes after the offset + length in order to pad this body to a 4 byte boundary. Parameters: data - A blob of binary data which should be copied into the output length - Number of characters of data to copy offset - Offset into the body to start copying """ while self.__body_len < (length + offset): self.__body.append(0) self.__body_len = self.__body_len + 1 # Make sure its padded to 4 bytes while (self.__body_len & 0x3) != 0: self.__body.append(0) self.__body_len = self.__body_len + 1 for i in range(length): self.__body[offset + i] = data[i] def get_data(self) -> bytes: """ Encode the header and body into binary formrt. Returns: Binary blob of data that can be decoded by a game. """ if self.executed: raise Exception("Logic error, should only call this once per instance") self.executed = True # Generate the header first self.__write_node(self.tree) self.stream.write_int(Node.END_OF_DOCUMENT) self.stream.write_pad(4) header_length = len(self.stream.data) header = self.stream.data[:] # Generate the body values = PackedOrdering.node_to_body_ordering(self.tree) if len(values) > 0: ordering = PackedOrdering(0, allow_expansion=True) for value in values: node = value['node'] if value['type'] == 'attribute': size = None enc = 's' dtype = 'str' array = False composite = False val = node.attribute(value['name']) else: size = node.data_length enc = node.data_encoding dtype = node.data_type array = node.is_array composite = node.is_composite val = node.value if val is None: raise BinaryEncodingException( f'Node \'{value["name"]}\' has invalid value None', ) if not array: # Scalar value alignment = value['alignment'] if alignment == 1: loc = ordering.get_next_byte() elif alignment == 2: loc = ordering.get_next_short() elif alignment == 4: loc = ordering.get_next_int() if loc is None: raise BinaryEncodingException("Ran out of data when attempting to allocate node location!") if dtype == 'str': # Need to convert this to encoding from standard string. # Also, need to lob off the trailing null. if not isinstance(val, str): raise BinaryEncodingException( f'Node \'{value["name"]}\' has non-string value!', ) try: valbytes = val.encode(self.encoding) + b'\0' except UnicodeEncodeError: raise BinaryEncodingException( f'Node \'{value["name"]}\' has un-encodable string value \'{val}\'' ) size = len(valbytes) self.__add_data(struct.pack('>I', size) + valbytes, size + 4, loc) ordering.mark_used(size + 4, loc, round_to=4) # We took care of this one continue elif dtype == 'bin': # Store raw binary size = len(val) self.__add_data(struct.pack('>I', size) + val, size + 4, loc) ordering.mark_used(size + 4, loc, round_to=4) # We took care of this one continue elif composite: # Array, but not, somewhat silly if size is None: raise Exception("Logic error, node size not set yet this is not an attribute!") encode_value = f'>{enc}' self.__add_data(struct.pack(encode_value, *val), size, loc) ordering.mark_used(size, loc) # We took care of this one continue elif dtype == 'bool': val = 1 if val else 0 # The size is built-in, emit it if size is None: raise Exception("Logic error, node size not set yet this is not an attribute!") encode_value = f'>{enc}' self.__add_data(struct.pack(encode_value, val), size, loc) ordering.mark_used(size, loc) else: # Array value loc = ordering.get_next_int() if loc is None: raise BinaryEncodingException("Ran out of data when attempting allocate array location!") if size is None: raise Exception("Logic error, node size not set yet this is not an attribute!") # The raw size in bytes elems = len(val) length = elems * size # Write out the header (number of bytes taken up) data = struct.pack('>I', length) encode_value = f'>{enc}' # Write out data one element at a time for v in val: if dtype == 'bool': data = data + struct.pack(encode_value, 1 if v else 0) else: data = data + struct.pack(encode_value, v) self.__add_data(data, length + 4, loc) ordering.mark_used(length + 4, loc, round_to=4) return b''.join([ struct.pack('>I', header_length), header, struct.pack('>I', self.__body_len), bytes(self.__body), ]) class BinaryEncoding: """ Wrapper class representing a Binary Encoding. """ MAGIC: Final[int] = 0xA0 COMPRESSED_WITH_DATA: Final[int] = 0x42 COMPRESSED_WITHOUT_DATA: Final[int] = 0x43 DECOMPRESSED_WITH_DATA: Final[int] = 0x45 DECOMPRESSED_WITHOUT_DATA: Final[int] = 0x46 # The string values should match the constants in EAmuseProtocol. # I have no better way to link these than to write this comment, # as otherwise we would have a circular dependency. ENCODINGS: Final[Dict[int, str]] = { 0x00: "ascii", 0x20: "shift-jis-legacy", 0x60: "euc-jp", 0x80: "shift-jis", 0xA0: "utf-8", } def __init__(self) -> None: """ Initialize the encoding object. """ self.encoding: Optional[str] = None def __sanitize_encoding(self, enc: str) -> str: """ Convert an internal encoding value from an externally acceptible value. Parameters: enc - The encoding as a string as passed from an outside caller Returns: An encoding string suitable for internal use. """ if enc == "shift-jis-legacy": return "shift-jis" return enc def decode(self, data: bytes, skip_on_exceptions: bool=False) -> Optional[Node]: """ Given a data blob, decode the data with the current encoding. Will also set the class property value 'encoding' to the encoding used on the last decode. Parameters: data - Binary blob representing the data to decode Returns: Node object representing the root of the decoded tree, or None if we couldn't decode the object for some reason. """ try: data_magic, contents, encoding_raw, encoding_swapped = struct.unpack(">BBBB", data[0:4]) except struct.error: # Couldn't even parse magic return None if data_magic != BinaryEncoding.MAGIC: return None if ((~encoding_raw) & 0xFF) != encoding_swapped: return None if contents not in [BinaryEncoding.COMPRESSED_WITH_DATA, BinaryEncoding.COMPRESSED_WITHOUT_DATA]: # We don't support uncompressed data. return None encoding = BinaryEncoding.ENCODINGS.get(encoding_raw) if encoding is not None: self.encoding = encoding try: decoder = BinaryDecoder(data[4:], self.__sanitize_encoding(encoding)) return decoder.get_tree() except BinaryEncodingException: if skip_on_exceptions: return None else: raise else: return None def encode(self, tree: Node, encoding: Optional[str]=None) -> bytes: """ Given a tree of Node objects, encode the data with the current encoding. Parameters: tree - Node tree representing the data to encode encoding - The text encoding to use. If None, will try to use the encoding from the last successful decode Returns: Binary blob representing encoded data """ if encoding is None: encoding = self.encoding if encoding is None: raise BinaryEncodingException('Unknown encoding') encoding_magic = None for magic, encstr in BinaryEncoding.ENCODINGS.items(): if encstr == encoding: encoding_magic = magic break if encoding_magic is None: raise BinaryEncodingException(f"Invalid text encoding {encoding}") encoder = BinaryEncoder(tree, self.__sanitize_encoding(encoding)) data = encoder.get_data() return struct.pack(">BBBB", BinaryEncoding.MAGIC, BinaryEncoding.COMPRESSED_WITH_DATA, encoding_magic, (~encoding_magic & 0xFF)) + data