dhcparse

A zero-copy DHCPv4 parser.

This crate is especially suitable for writing DHCP relay agents, which only need to read and write a few fields, set and possibly remove a couple of options, before forwarding an incoming DHCP message.

Examples

Basic usage:

use dhcparse::{v4_options, dhcpv4::{Message, MessageType}};
use std::net::Ipv4Addr;

let mut msg = Message::new(EXAMPLE_DISCOVER_MSG)?;

// Read a field
assert_eq!(msg.chaddr()?, [0x01, 0x02, 0x03, 0x04, 0x05, 0x06]);

// Set a field
*msg.giaddr_mut() = Ipv4Addr::new(192, 168, 1, 50).into();

// Parse a set of options
assert_eq!(
    v4_options!(msg; MessageType required, ServerIdentifier, RequestedIpAddress)?,
    (
        MessageType::DISCOVER,
        None,
        Some(&Ipv4Addr::new(192, 168, 1, 100).into())
    )
);

Constructing a new message:

use dhcparse::dhcpv4::{DhcpOption, Encode as _, Encoder, Message, MessageType, OpCode};
// Create a copy of an empty message with the message type option added
let mut msg = Encoder
    .append_option(DhcpOption::MessageType(MessageType::DISCOVER))
    .encode_to_owned(&Message::default())?;
msg.set_op(OpCode::BootRequest);

assert_eq!(msg.options()?.count(), 1);

Related projects

• dhcproto is another Rust crate that instead parses DHCP messages into an owned representation. This may be more convenient for some applications, but comes with the overhead of copying and heap allocations. For instance, the current set of dhcproto benchmarks would be no-ops with dhcparse.