Data type to represent an IPv4 packet header. More...

Detailed Description

Data type to represent an IPv4 packet header.

The structure of the header is as follows:

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version|  IHL  |Type of Service|          Total Length         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|         Identification        |Flags|      Fragment Offset    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  Time to Live |    Protocol   |         Header Checksum       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                       Source Address                          |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                    Destination Address                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                    Options                    |    Padding    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

See also: RFC 791, section 3.1

Definition at line 55 of file hdr.h.

#include <hdr.h>

Data Fields
uint8_t	v_ih
	Version and Internet Header Length.

uint8_t	ts
	type of service of packet

network_uint16_t	tl
	total length of the datagram

network_uint16_t	id
	identification value of packet

network_uint16_t	fl_fo
	version control flags and Fragment Offset.

uint8_t	ttl
	time to live for this packet

uint8_t	protocol
	protocol of this packet

network_uint16_t	csum
	checksum of this packet

ipv4_addr_t	src
	source address of this packet

ipv4_addr_t	dst
	destination address of this packet

Field Documentation

◆ csum

network_uint16_t ipv4_hdr_t::csum

checksum of this packet

Definition at line 88 of file hdr.h.

◆ dst

ipv4_addr_t ipv4_hdr_t::dst

destination address of this packet

Definition at line 90 of file hdr.h.

◆ fl_fo

network_uint16_t ipv4_hdr_t::fl_fo

version control flags and Fragment Offset.

The flags are the 3 most significant bits, and the remaining 13 bits are the fragment offset

This module provides helper functions to set, get, and check these fields accordingly:

Definition at line 85 of file hdr.h.

◆ id

network_uint16_t ipv4_hdr_t::id

identification value of packet

Definition at line 72 of file hdr.h.

◆ protocol

uint8_t ipv4_hdr_t::protocol

protocol of this packet

Definition at line 87 of file hdr.h.

◆ src

ipv4_addr_t ipv4_hdr_t::src

source address of this packet

Definition at line 89 of file hdr.h.

◆ tl

network_uint16_t ipv4_hdr_t::tl

total length of the datagram

Definition at line 71 of file hdr.h.

◆ ts

uint8_t ipv4_hdr_t::ts

type of service of packet

Definition at line 70 of file hdr.h.

◆ ttl

uint8_t ipv4_hdr_t::ttl

time to live for this packet

Definition at line 86 of file hdr.h.

◆ v_ih

uint8_t ipv4_hdr_t::v_ih

Version and Internet Header Length.

The version are the 4 most significant bits and the Internet Header Length the 4 next bit (see above).