Repository restructuring

utils/packeter.py

@@ -0,0 +1,133 @@
+import struct
+
+class StructWrapper:
+    @staticmethod
+    def _endian(e):
+        return ">" if e else "<"
+
+    @staticmethod
+    def _format_size(f):
+        format_sizes = {
+            "c": 1,
+            "h": 2, "H": 2,
+            "i": 4, "I": 4,
+            "q": 8, "Q": 8,
+        }
+
+        assert f in format_sizes
+        return format_sizes[f]
+
+class Parser(StructWrapper):
+    def __init__(self, data, big_endian=False):
+        self.data = data
+        self.offset = 0
+        self.big_endian = big_endian
+
+    def eof(self):
+        return self.offset >= len(self.data)
+
+    def remaining_size(self):
+        return len(self.data[self.offset:])
+
+    def _struct_unpack(self, big_endian, f):
+        size = self._format_size(f)
+        assert self.remaining_size() >= size
+
+        # grab default endianess, when none is given
+        if big_endian is None:
+            big_endian = self.big_endian
+
+        value = struct.unpack(self._endian(big_endian) + f, self.data[self.offset:self.offset+size])[0]
+        self.offset += size
+        return value
+
+    def read_byte(self):
+        return self._struct_unpack(big_endian, "c")
+
+    def read_char(self):
+        return chr(self.read_byte())
+
+    def read_signed_short(self, big_endian=None):
+        return self._struct_unpack(big_endian, "h")
+
+    def read_unsigned_short(self, big_endian=None):
+        return self._struct_unpack(big_endian, "H")
+
+    def read_signed_int(self, big_endian=None):
+        return self._struct_unpack(big_endian, "i")
+
+    def read_unsigned_int(self, big_endian=None):
+        return self._struct_unpack(big_endian, "I")
+
+    def read_signed_long(self, big_endian=None):
+        return self._struct_unpack(big_endian, "q")
+
+    def read_unsigned_long(self, big_endian=None):
+        return self._struct_unpack(big_endian, "Q")
+
+    def read_bin(self, length):
+        d = self.data[self.offset:self.offset+length]
+        assert len(self.data[self.offset:]) >= length
+        self.offset += length
+        return d
+
+    def read_until(self, byte):
+        data = b""
+        while not self.eof():
+            c = self.read_byte()
+            if c == byte:
+                break
+            data += c
+        return data
+
+class Packer(StructWrapper):
+    def __init__(self, big_endian=False):
+        self.buffer = b""
+        self.offset = 0
+        self.big_endian = big_endian
+
+    def get(self):
+        return self.buffer
+
+    def length(self):
+        return len(self.buffer)
+
+    def _struct_pack(self, big_endian, f, value):
+        # grab default endianess, when none is given
+        if big_endian is None:
+            big_endian = self.big_endian
+
+        size = self._format_size(f)
+        self.buffer += struct.pack(self._endian(big_endian) + f, value)
+        self.offset += size
+
+    def write_byte(self, value):
+        self._struct_pack(big_endian, "c", value)
+
+    def write_char(self, value):
+        self._struct_pack(big_endian, "c", value.encode())
+
+    def write_signed_short(self, value, big_endian=None):
+        self._struct_pack(big_endian, "c", value)
+
+    def write_unsigned_short(self, value, big_endian=None):
+        self._struct_pack(big_endian, "H", value)
+
+    def write_signed_int(self, value, big_endian=None):
+        self._struct_unpack(big_endian, "i", value)
+
+    def write_unsigned_int(self, value, big_endian=None):
+        self._struct_unpack(big_endian, "I", value)
+
+    def write_signed_long(self, value, big_endian=None):
+        self._struct_unpack(big_endian, "q", value)
+
+    def rwrite_unsigned_long(self, value, big_endian=None):
+        self._struct_unpack(big_endian, "Q", value)
+
+    def write_bin(self, value):
+        self.buffer += value
+        self.offset += len(value)
+
+    def write_string(self, value, encoding="UTF-8"):
+        self.write_bin(value.encode(encoding))