added payload utils

PayloadBuilder.py

@@ -0,0 +1,61 @@
+import struct
+
+class PayloadBuilder:
+    """
+    Utility for building binary payloads
+    """
+
+    def __init__(self, endian='little'):
+        self.buf = bytearray()
+        self.endian = endian
+
+    def close(self):
+        """ Get the byte buffer """
+        return self.buf
+
+    def u8(self, num):
+        """ Add a uint8_t """
+        self.buf.extend(num.to_bytes(length=1, byteorder=self.endian, signed=False))
+
+    def u16(self, num):
+        """ Add a uint16_t """
+        self.buf.extend(num.to_bytes(length=2, byteorder=self.endian, signed=False))
+
+    def u32(self, num):
+        """ Add a uint32_t """
+        self.buf.extend(num.to_bytes(length=4, byteorder=self.endian, signed=False))
+
+    def i8(self, num):
+        """ Add a int8_t """
+        self.buf.extend(num.to_bytes(length=1, byteorder=self.endian, signed=True))
+
+    def i16(self, num):
+        """ Add a int16_t """
+        self.buf.extend(num.to_bytes(length=2, byteorder=self.endian, signed=True))
+
+    def i32(self, num):
+        """ Add a int32_t """
+        self.buf.extend(num.to_bytes(length=4, byteorder=self.endian, signed=True))
+
+    def float(self, num):
+        """ Add a float (4 bytes) """
+        fmt = '<f' if self.endian == 'little' else '>f'
+        self.buf.extend(struct.pack(fmt, num))
+
+    def double(self, num):
+        """ Add a double (8 bytes) """
+        fmt = '<d' if self.endian == 'little' else '>d'
+        self.buf.extend(struct.pack(fmt, num))
+
+    def bool(self, num):
+        """ Add a bool (0 or 1) """
+        self.buf.append(1 if num != False else 0)
+
+    def str(self, string):
+        """ Add a 0-terminated string """
+        self.buf.extend(string.encode('utf-8'))
+        self.buf.append(0)
+
+    def blob(self, blob):
+        """ Ad an arbitrary blob (bytearray or binary string) """
+        self.buf.extend(blob)

PayloadParser.py

@@ -0,0 +1,89 @@
+import struct
+
+class PayloadParser:
+    """
+    Utility for parsing a binary payload
+    """
+
+    def __init__(self, buf, endian='little'):
+        """ buf - buffer to parse (bytearray or binary string) """
+        self.buf = buf
+        self.ptr = 0
+        self.endian = endian
+
+    def _slice(self, n):
+        """ Extract a slice and advance the read pointer for the next slice """
+        if self.ptr + n > len(self.buf):
+            raise Exception("Out of bounds")
+
+        slice = self.buf[self.ptr:self.ptr + n]
+        self.ptr += n
+        return slice
+
+    def rewind(self):
+        """ Reset the slice pointer to the beginning """
+        self.ptr = 0
+
+    def tail(self):
+        """ Get all remaining bytes """
+        return self._slice(len(self.buf) - self.ptr)
+
+    def u8(self):
+        """ Read a uint8_t """
+        slice = self._slice(1)
+        return int.from_bytes(slice, byteorder=self.endian, signed=False)
+
+    def u16(self):
+        """ Read a uint16_t """
+        slice = self._slice(2)
+        return int.from_bytes(slice, byteorder=self.endian, signed=False)
+
+    def u32(self):
+        """ Read a uint32_t """
+        slice = self._slice(4)
+        return int.from_bytes(slice, byteorder=self.endian, signed=False)
+
+    def i8(self):
+        """ Read a int8_t """
+        slice = self._slice(1)
+        return int.from_bytes(slice, byteorder=self.endian, signed=True)
+
+    def i16(self):
+        """ Read a int16_t """
+        slice = self._slice(2)
+        return int.from_bytes(slice, byteorder=self.endian, signed=True)
+
+    def i32(self):
+        """ Read a int32_t """
+        slice = self._slice(4)
+        return int.from_bytes(slice, byteorder=self.endian, signed=True)
+
+    def float(self):
+        """ Read a float (4 bytes) """
+        slice = self._slice(4)
+        fmt = '<f' if self.endian == 'little' else '>f'
+        return struct.unpack(fmt, slice)[0]
+
+    def double(self):
+        """ Read a double (8 bytes) """
+        slice = self._slice(8)
+        fmt = '<d' if self.endian == 'little' else '>d'
+        return struct.unpack(fmt, slice)[0]
+
+    def bool(self):
+        """ Read a bool (1 byte, True if != 0) """
+        return 0 != self._slice(1)[0]
+
+    def str(self):
+        """ Read a zero-terminated string """
+        p = self.ptr
+        while p < len(self.buf) and self.buf[p] != 0:
+            p += 1
+
+        bs = self._slice(p - self.ptr)
+        self.ptr += 1
+        return bs.decode('utf-8')
+
+    def blob(self, length):
+        """ Read a blob of given length """
+        return self._slice(length)

TinyFrame.py

@@ -1,19 +1,3 @@
-class TF_Msg:
-    def __init__(self):
-        self.data = bytearray()
-        self.len = 0
-        self.type = 0
-        self.id = 0
-
-    def __str__(self):
-        return f"ID {self.id:X}h, type {self.type:X}h, len {self.len:d}, body: {self.data}"
-
-class TF:
-    STAY = 'STAY'
-    RENEW = 'RENEW'
-    CLOSE = 'CLOSE'
-    NEXT = 'NEXT'
-
 class TinyFrame:
     def __init__(self, peer=1):
         self.write = None # the writer function should be attached here
@@ -349,19 +333,18 @@ class TinyFrame:
             'fn': lst,
         }
 
+class TF_Msg:
+    def __init__(self):
+        self.data = bytearray()
+        self.len = 0
+        self.type = 0
+        self.id = 0
 
+    def __str__(self):
+        return f"ID {self.id:X}h, type {self.type:X}h, len {self.len:d}, body: {self.data}"
 
-
+class TF:
-
+    STAY = 'STAY'
-
+    RENEW = 'RENEW'
-
+    CLOSE = 'CLOSE'
-
+    NEXT = 'NEXT'
-
-
-
-
-
-
-
-
-