Crate rips_packets

Overview

Network protocol packet representations. types that encapsulate byte slices (&[u8]) in a zero allocation, zero copy, zero-cost way and provide getter and setter methods for the fields in the corresponding protocols.

All packet types in this crate are represented by two structs, one for immutable data (used to read header fields) and one for mutable data (used to set header fields). These structs are defined like this:

pub struct FooPacket<'a>(&'a [u8]);
pub struct MutFooPacket<'a>(&'a mut [u8]);

Creating an immutable packet is done with FooPacket::new(a_slice_of_u8) and a mutable one with MutFooPacket::new(a_mut_slice_of_u8). This returns a new packet instance after making sure the given slice is at least as long as the header of a "Foo packet". The packet types has getters and setters for each header field. A getter/setter only bitshifts, masks out and optionally do endianess conversion of the bytes in the backing buffer, making the operations very cheap.

Usage

See the examples in examples/ for more examples.

extern crate rips_packets;

use rips_packets::ethernet::{EthernetPacket, MacAddr, MutEthernetPacket, EtherType};

fn main() {
    // Allocate a byte buffer that hold the bytes in the Ethernet frame.
    let mut buffer = [0; 14];

    {
        // Lend the buffer mutably to `MutEthernetPacket` so it can manipulate the
        // header fields.
        let mut ethernet_packet = MutEthernetPacket::new(&mut buffer[..])
            .expect("Too short buffer");

        // Use the setter methods to change the data in `buffer`
        ethernet_packet.set_destination(MacAddr::BROADCAST);
        ethernet_packet.set_source(MacAddr([0x01, 0x02, 0x03, 0x04, 0x05, 0x06]));
        ethernet_packet.set_ether_type(EtherType::IPV4);
    }

    // Create an immutable representation of the ethernet frame based on the same
    // buffer. Where a mutable `MutEthernetPacket` has setters `EthernetPacket` has the
    // corresponding getters.
    let packet = EthernetPacket::new(&buffer[..]).expect("Too short buffer");

    println!("Destination MAC: {}", packet.destination());
    println!("Source MAC: {}", packet.source());
    println!("EtherType: {:?}", packet.ether_type());
    println!("Packet data, including header: {:?}", packet.data())
}

Prior art and comparison

This crate is heavily inspired by pnet_packet from pnet. Basically this is a rewrite of that part of pnet with the purpose of being more light weight and versatile. The packet code generation in pnet is cool and very useful. But it brings in large and outdated dependencies (syntex), and somewhat limits what a packet can do. In comparison rips-packets aims to have no/very few dependencies at the cost of more manual work to implement each protocol representation. A benefit of the more manual implementations is that it is easy to hand optimize single getters or setters if needed.

Compiling rips-packets takes under a second on a modern computer, whereas pnet_packet take well over a minute on the same hardware.

Modules

arp
ethernet	Link layer primitives.
ip
ipv4
ipv6
types	Bit field type aliases.