Packet Manipulator

RFQuacks comes with a powerful packet modification module:

  • q.packet_modification.add() takes several parameters:
  • position (number, optional) indicates the position in the payload that will be modified (e.g., 3rd byte);
  • content (byte, optional) indicates the content that will be modified (e.g., all octects which value is 'A');
  • pattern (optional) same as for the filter: only packets matching the pattern will be modified; if no pattern is specified, all packets will be modified.
  • operation (enum) is the action to be performed, available operations are:
    • (AND, OR, XOR, NOT, SLEFT, SRIGHT) + operand field.
    • (PREPEND, APPEND, INSERT) + payload field.
    • NOT.
  • operand (byte) is the "right" value for the operations that need it (AND, OR, XOR, NOT, SLEFT, SRIGHT).
  • payload (byte) is the "payload" value for the operations that need it (PREPEND, APPEND, INSERT).
  • pattern (string) a regular-expression pattern complying with the tiny-regex-c, to restrict modifications to matching packets only.
  • q.packet_modification.reset() will delete any stored rule.
  • q.packet_modification.dump() will dump to CLI any stored rule.
  • q.packet_modification.auto_shift (boolean), if enabled the module will automatically left shifts packets matching ^5555 to get ^aaaa packets.
  • q.packet_modification.enabled (boolean), controls whatever the module is enabled, do not forget to set it!

Example: Let's say that you want to invert byte 3 of all packets that end with 'XYZ' and XOR with 0x44 all bytes which value is 'A' (and in position 5) of all packets that start with 'AAA'. And you want to ignore any packet that do not contain at least 3 digits in their payload. You're going to need two modifications and one filter:

In [72]: q.packet_filter.add(
    pattern="[0-9]{3,}"  # ignore packets not containing at least 3 digits

# ...

In [73]: q.packet_modification.add(
    pattern="XYZ$"  # for all packets that end in "XYZ"
    position=3,     # at position 3
    operation=4     # apply a NOT of whatever value is there
                    # (no operand needed)

# ...

In [74]: q.packet_modification.add(
    pattern="^AAA"  # for all packets that start with "AAA"
    content=0x42,   # for all octects which value equals A
    position=5,     # and at position 5
    operation=3     # XOR the value with the operand

In [76]: q.packet_filter.enabled = True # enable packet filtering
In [77]: q.packet_modification.enabled = True # enable packet manipulation

Example: Let's say you are capturing packets by mean of a specific syncword filter; the radio will consume the preamble and the specified syncword to recognize the packet and, consequently, sends you the remaining payload. You are not happy with this and want to prepend the consumed part. Well, nothing easier:

In [78]: q.packet_modification.add(
    operation="PREPEND",                      # Select prepend action
    payload=bytes.fromhex("aaaaaaaaaae5e5")   # Prepend the consumed preamble and the syncword (\xE5\xE5)
In [79]: q.packet_modification.enabled = True # enable packet manipulation