Struct etherparse::Ipv4Header

pub struct Ipv4Header {
    pub differentiated_services_code_point: u8,
    pub explicit_congestion_notification: u8,
    pub payload_len: u16,
    pub identification: u16,
    pub dont_fragment: bool,
    pub more_fragments: bool,
    pub fragments_offset: u16,
    pub time_to_live: u8,
    pub protocol: u8,
    pub header_checksum: u16,
    pub source: [u8; 4],
    pub destination: [u8; 4],
    // some fields omitted
}

IPv4 header without options.

Fields

differentiated_services_code_point: u8

explicit_congestion_notification: u8

payload_len: u16

Length of the payload of the ipv4 packet in bytes (does not contain the options).

This field does not directly exist in an ipv4 header but instead is decoded from & encoded to the total_size field together with the options length (using the ihl). If the total_length field in a ipv4 header is smaller then

identification: u16

dont_fragment: bool

more_fragments: bool

fragments_offset: u16

time_to_live: u8

protocol: u8

header_checksum: u16

source: [u8; 4]

destination: [u8; 4]

Methods

impl Ipv4Header

pub fn new(
    payload_len: u16,
    time_to_live: u8,
    protocol: IpTrafficClass,
    source: [u8; 4],
    destination: [u8; 4]
) -> Ipv4Header

Constructs an Ipv4Header with standard values for non specified values.

pub fn ihl(&self) -> u8

Length of the header in 4 bytes (often also called IHL - Internet Header Lenght).

The minimum allowed length of a header is 5 (= 20 bytes) and the maximum length is 15 (= 60 bytes).

pub fn options(&self) -> &[u8]

Returns a slice to the options part of the header (empty if no options are present).

pub fn header_len(&self) -> usize

Length of the header (includes options) in bytes.

pub fn total_len(&self) -> u16

Returns the total length of the header + payload in bytes.

pub fn set_payload_len(&mut self, value: usize) -> Result<(), ValueError>

Sets the payload length if the value is not too big. Otherwise an error is returned.

pub fn max_payload_len(&self) -> u16

Returns the maximum payload size based on the current options size.

pub fn set_options(&mut self, data: &[u8]) -> Result<(), ValueError>

Sets the options & header_length based on the provided length. The length of the given slice must be a multiple of 4 and maximum 40 bytes. If the length is not fullfilling these constraints, no data is set and an error is returned.

pub fn read_from_slice(slice: &[u8]) -> Result<(Ipv4Header, &[u8]), ReadError>

Read an Ipv4Header from a slice and return the header & unused parts of the slice.

pub fn read<T: Read + Seek + Sized>(
    reader: &mut T
) -> Result<Ipv4Header, ReadError>

Reads an IPv4 header from the current position.

pub fn read_without_version<T: Read + Seek + Sized>(
    reader: &mut T,
    version_rest: u8
) -> Result<Ipv4Header, ReadError>

Reads an IPv4 header assuming the version & ihl field have already been read.

pub fn check_ranges(&self) -> Result<(), ValueError>

Checks if the values in this header are valid values for an ipv4 header.

Specifically it will be checked, that:

• payload_len + options_len is not too big to be encoded in the total_size header field
• differentiated_services_code_point is not greater then 0x3f
• explicit_congestion_notification is not greater then 0x3
• fragments_offset is not greater then 0x1fff

pub fn write<T: Write + Sized>(&self, writer: &mut T) -> Result<(), WriteError>

Writes a given IPv4 header to the current position (this method automatically calculates the header length and checksum).

pub fn write_raw<T: Write + Sized>(
    &self,
    writer: &mut T
) -> Result<(), WriteError>

Writes a given IPv4 header to the current position (this method just writes the specified checksum and does note compute it).

pub fn calc_header_checksum(&self) -> Result<u16, ValueError>

Calculate header checksum of the current ipv4 header.

Trait Implementations

impl SerializedSize for Ipv4Header

const SERIALIZED_SIZE: usize

Size of the header itself (without options) in bytes.

impl Default for Ipv4Header

fn default() -> Ipv4Header

Returns the "default value" for a type.

impl Clone for Ipv4Header

fn clone(&self) -> Ipv4Header

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Eq for Ipv4Header

impl PartialEq<Ipv4Header> for Ipv4Header

fn eq(&self, other: &Ipv4Header) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl Debug for Ipv4Header

fn fmt(&self, fotmatter: &mut Formatter) -> Result<(), Error>

Formats the value using the given formatter.