PyPISS (v0.1)

Python Packet parser generator In Simple Structured format

Intro

PyPISS is a simple packet parser generator framework inspired by P4 Lang
If you tired about making every packet formats or,
If you want to make your own packet format (such as researching, game socket io, etc…)
This framework may be helpful for creating packet builder/parser.

Specification

Support bit,byte,short,int,string,list and so on …
Declare packet’s structure and setting each fields default value or action easily (such as CRC, Flag)
Creating packet by declared packet’s structure
Automatic validity check from packet’s structure
Creating new packet structure by compositing another packet’s structure

Supporting types

1. primitives

name	c-style type name	size(bytes)	note
bool	bool (not same size)	1bit	True / False
char	signed char	1
byte	unsigned char	1
short	signed short	2
u_short	unsigned short	2
int	signed long int	4
u_int	unsigned long int	4
long	signed long long int	8
u_long	unsigned long long int	8
float	float	4
double	double	8

2. iteratives

name	c-style type name	size(bytes)	note
str(size)	char[]	vary	return in python string
bytes(size)	unsigned char[]	vary	return in byte array
arr(size)	array of type	vary	return in list, must use with type

3. structures

name	c-style type name	size(bytes)	note
ipv4	byte[4]	4	return in IPv4 python class
ipv6	short[8]	16	return in IPv6 python class
hmac	byte[6]	6	return in HMAC python class

Supporting operators

{typename}(bits=0) : set field’s type, if bits is 0 then using default bit size.
val(val) : set default value for {val} when build
val(lambda) : set default value by lambda function when build
check(lambda) : check value by lambda function when parse

Installation

Python 2.x : pip install pypiss
Python 3.x : pip3 install pypiss

Example

IPv4 with Custom Packets

import enum.Enum
from pypiss.PacketStructure import *
from pypiss.PacketUtil import CRC32
class EtherType(Enum):
    IPV4 = 0x0800,
    ARP = 0x0806
class EthernetFrame(PacketHeader):
    _field = [
        field("dst").hmac(),
        field("src").hmac(),
        field("ether_type").u_short().enum(EtherType),
        field("payload").bytes(),   # if skip to define size, auto calculated from rest bytes
        field("crc").int().val(CRC32.make(['payload'])).check() # if skip to define check function, use same logic from make
    ]
class IPv4Frame(PacketHeader):
    _field = [
        field("src").ipv4(),
        field("dst").ipv4(),
        ...,
        field("len").u_short(),
        ...,
        field("payload").bytes()
    ]
    def parse(self, data):
        self.
        # In this function, all fields except payload should be assigned
class PingPongFrame(PacketHeader):
    _field = [
        field(type).byte(bits=3),
        payload()
    ]

Roadmap

See in ‘Issues’

make converter p4 lang to piss python structure

Contribution

I always need your helps.
don’t be shy, don’t hesitate, just fork & pull request thx!

If you have any suggestion (feature request, etc…), feel free to contact me!