Crate catnip

Expand description

A no-std, panic-never, heapless, minimally-featured UDP/IP stack for bare-metal. Intended for fixed-time data acquisition and controls on LAN.

This crate currently relies on the nightly channel, and as a result, may break regularly until the required features stabilize.

Makes use of const generic expressions to provide flexibility in, and guaranteed correctness of, lengths of headers and data segments without an allocator.

This library is under active development; major functionality is yet to be implemented and I’m sure some bugs are yet to be found.

use catnip::*;

// Some made-up data with two 32-bit words' worth of bytes and some arbitrary addresses
let data: ByteArray<8> = ByteArray([0, 1, 2, 3, 4, 5, 6, 7]);

// Build frame
let mut frame = EthernetFrame::<IpV4Frame<UdpFrame<ByteArray<8>>>> {
    header: EthernetHeader {
        dst_macaddr: MacAddr::BROADCAST,
        src_macaddr: MacAddr::new([0x02, 0xAF, 0xFF, 0x1A, 0xE5, 0x3C]),
        ethertype: EtherType::IpV4,
    },
    data: IpV4Frame::<UdpFrame<ByteArray<8>>> {
        header: IpV4Header {
            version_and_header_length: VersionAndHeaderLength::new().with_version(4).with_header_length((IpV4Header::BYTE_LEN / 4) as u8),
            dscp: DSCP::Standard,
            total_length: IpV4Frame::<UdpFrame<ByteArray<8>>>::BYTE_LEN as u16,
            identification: 0,
            fragmentation: Fragmentation::default(),
            time_to_live: 10,
            protocol: Protocol::Udp,
            checksum: 0,
            src_ipaddr: IpV4Addr::new([10, 0, 0, 120]),
            dst_ipaddr: IpV4Addr::new([10, 0, 0, 121]),
        },
        data: UdpFrame::<ByteArray<8>> {
            header: UdpHeader {
                src_port: 8123,
                dst_port: 8125,
                length: UdpFrame::<ByteArray<8>>::BYTE_LEN as u16,
                checksum: 0,
            },
            data: data,
        },
    },
    checksum: 0_u32,
};

// Calculate IP and UDP checksums
frame.data.data.header.checksum = calc_udp_checksum(&frame.data);
frame.data.header.checksum = calc_ip_checksum(&frame.data.header.to_be_bytes());

// Reduce to bytes
let bytes = frame.to_be_bytes();

// Parse from bytes
let frame_parsed = EthernetFrame::<IpV4Frame<UdpFrame<ByteArray<8>>>>::read_bytes(&bytes);
assert_eq!(frame_parsed, frame);

Re-exports§

pub use modular_bitfield;
pub use arp::*;
pub use dhcp::*;
pub use enet::*;
pub use ip::*;
pub use udp::*;

Modules§

arp: Address Resolution Protocol implementation for IPV4.
dhcp: Dynamic Host Configuration Protocol for IPV4.
enet: Link layer: Ethernet II protocol. See https://en.wikipedia.org/wiki/Ethernet_frame#Ethernet_II.
ip: Internet layer: Internet Protocol message header construction
udp: Transport layer: User Datagram Protocol

Macros§

enum_with_unknown: Derive To/From with an added “Unknown” variant catch-all for converting from numerical values that do not match a valid variant in order to avoid either panicking or cumbersome error handling.

Structs§

ByteArray: Newtype for [u8; N] in order to be able to implement traits.

Enums§

DSCP: Type-of-Service for networks with differentiated services. See https://en.wikipedia.org/wiki/Differentiated_services.
Protocol: Common choices of transport-layer protocols and their IP header values. There are many more protocols not listed here. See https://en.wikipedia.org/wiki/List_of_IP_protocol_numbers.

Traits§

ByteStruct: A data structure that can be packed into or unpacked from raw bytes.
ByteStructLen: A type that can be packed into or unpacked from fixed-size bytes, but the method is unknown yet.
uDebug: Just like core::fmt::Debug
uDisplay: Just like core::fmt::Display
uWrite: A collection of methods that are required / used to format a message into a stream.

Functions§

calc_ip_checksum: Calculate IP checksum per IETF-RFC-768 following implementation guide in IETF-RFC-1071 section 4.1 . See https://datatracker.ietf.org/doc/html/rfc1071#section-4 . This function is provided for convenience and is not used directly.
calc_ip_checksum_finalize: Finalize an IP checksum by folding the accumulator from an i32 to a u16 and taking the one’s complement
calc_ip_checksum_incomplete: Calculate an IP checksum on incomplete data returning the unfolded accumulator as i32

Type Aliases§

IpV4Addr: IPV4 address as bytes
MacAddr: Standard 6-byte MAC address. Split 24/24 format, Block ID | Device ID . Locally-administered addresses are [0x02, …], [0x06, …], [0x0A, …], [0x0E, …]

Derive Macros§

ByteStruct: Derives trait ByteStruct for a data structure.
uDebug: Automatically derive the uDebug trait for a struct or enum

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