IPv4 Internet datagram header More...

#include <ipv4_header.hh>

Public Member Functions
ParseResult	parse (NetParser &p)
	Parse the IP fields from the provided NetParser. More...

uint16_t	payload_length () const
	Length of the payload. More...

uint32_t	pseudo_cksum () const
	pseudo-header's contribution to the TCP checksum More...

std::string	serialize () const
	Serialize the IP fields. More...

std::string	summary () const
	Return a string containing a human-readable summary of the header. More...

std::string	to_string () const
	Return a string containing a header in human-readable format. More...

Public Attributes
IPv4 Header fields
uint8_t	ver = 4
	IP version. More...

uint8_t	hlen = LENGTH / 4
	header length (multiples of 32 bits) More...

uint8_t	tos = 0
	type of service More...

uint16_t	len = 0
	total length of packet More...

uint16_t	id = 0
	identification number More...

bool	df = true
	don't fragment flag More...

bool	mf = false
	more fragments flag More...

uint16_t	offset = 0
	fragment offset field More...

uint8_t	ttl = DEFAULT_TTL
	time to live field More...

uint8_t	proto = PROTO_TCP
	protocol field More...

uint16_t	cksum = 0
	checksum field More...

uint32_t	src = 0
	src address More...

uint32_t	dst = 0

Static Public Attributes
static constexpr uint8_t	DEFAULT_TTL = 128
	A reasonable default TTL value. More...

static constexpr size_t	LENGTH = 20
	IPv4 header length, not including options More...

static constexpr uint8_t	PROTO_TCP = 6
	Protocol number for tcp. More...

Detailed Description

IPv4 Internet datagram header

Note: IP options are not supported

 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    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

This struct can be used to parse an existing IP header or to create a new one.

Definition at line 8 of file ipv4_header.hh.

Member Function Documentation

◆ parse()

ParseResult IPv4Header::parse ( NetParser & p )

Parse the IP fields from the provided NetParser.

Parameters

[in,out] p is a NetParser from which the IP fields will be extracted

Returns: a ParseResult indicating success or the reason for failure

It is important to check for (at least) the following potential errors (but note that NetParser inherently checks for certain errors; use that fact to your advantage!):

data stream is too short to contain a header
wrong IP version number
the header's hlen field is shorter than the minimum allowed
there is less data in the header than the doff field claims
there is less data in the full datagram than the len field claims
the checksum is bad

Definition at line 23 of file ipv4_header.cc.

◆ payload_length()

uint16_t IPv4Header::payload_length ( ) const

Length of the payload.

Definition at line 112 of file ipv4_header.cc.

◆ pseudo_cksum()

uint32_t IPv4Header::pseudo_cksum ( ) const

pseudo-header's contribution to the TCP checksum

This value is needed when computing the checksum of an encapsulated TCP segment.

 0      7 8     15 16    23 24    31
+--------+--------+--------+--------+
|          source address           |
+--------+--------+--------+--------+
|        destination address        |
+--------+--------+--------+--------+
|  zero  |protocol|  payload length |
+--------+--------+--------+--------+

Definition at line 125 of file ipv4_header.cc.

◆ serialize()

string IPv4Header::serialize ( ) const

Serialize the IP fields.

Serialize the IPv4Header to a string (does not recompute the checksum)

Definition at line 78 of file ipv4_header.cc.

◆ summary()

std::string IPv4Header::summary ( ) const

Return a string containing a human-readable summary of the header.

Definition at line 151 of file ipv4_header.cc.

◆ to_string()

std::string IPv4Header::to_string ( ) const

Return a string containing a header in human-readable format.

Returns: A string with the header's contents

Definition at line 134 of file ipv4_header.cc.

Member Data Documentation

◆ cksum

uint16_t IPv4Header::cksum = 0

checksum field

Definition at line 44 of file ipv4_header.hh.

◆ DEFAULT_TTL

constexpr uint8_t IPv4Header::DEFAULT_TTL = 128

staticconstexpr

A reasonable default TTL value.

Definition at line 10 of file ipv4_header.hh.

◆ df

bool IPv4Header::df = true

don't fragment flag

Definition at line 39 of file ipv4_header.hh.

◆ dst

uint32_t IPv4Header::dst = 0

dst address

Definition at line 46 of file ipv4_header.hh.

◆ hlen

uint8_t IPv4Header::hlen = LENGTH / 4

header length (multiples of 32 bits)

Definition at line 35 of file ipv4_header.hh.

◆ id

uint16_t IPv4Header::id = 0

identification number

Definition at line 38 of file ipv4_header.hh.

◆ len

uint16_t IPv4Header::len = 0

total length of packet

Definition at line 37 of file ipv4_header.hh.

◆ LENGTH

constexpr size_t IPv4Header::LENGTH = 20

staticconstexpr

IPv4 header length, not including options

Definition at line 9 of file ipv4_header.hh.

◆ mf

bool IPv4Header::mf = false

more fragments flag

Definition at line 40 of file ipv4_header.hh.

◆ offset

uint16_t IPv4Header::offset = 0

fragment offset field

Definition at line 41 of file ipv4_header.hh.

◆ proto

uint8_t IPv4Header::proto = PROTO_TCP

protocol field

Definition at line 43 of file ipv4_header.hh.

◆ PROTO_TCP

constexpr uint8_t IPv4Header::PROTO_TCP = 6

staticconstexpr

Protocol number for tcp.

Definition at line 11 of file ipv4_header.hh.

◆ src

uint32_t IPv4Header::src = 0

src address

Definition at line 45 of file ipv4_header.hh.

◆ tos

uint8_t IPv4Header::tos = 0

type of service

Definition at line 36 of file ipv4_header.hh.

◆ ttl

uint8_t IPv4Header::ttl = DEFAULT_TTL

time to live field

Definition at line 42 of file ipv4_header.hh.

◆ ver

uint8_t IPv4Header::ver = 4

IP version.

Definition at line 34 of file ipv4_header.hh.

The documentation for this struct was generated from the following files:

/home/cs144/sponge/libsponge/tcp_helpers/ipv4_header.hh
/home/cs144/sponge/libsponge/tcp_helpers/ipv4_header.cc

Public Member Functions

Public Attributes

Static Public Attributes

Detailed Description

Member Function Documentation

◆ parse()

◆ payload_length()

◆ pseudo_cksum()

◆ serialize()

◆ summary()

◆ to_string()

Member Data Documentation

◆ cksum

◆ DEFAULT_TTL

◆ df

◆ dst

◆ hlen

◆ id

◆ len

◆ LENGTH

◆ mf

◆ offset

◆ proto

◆ PROTO_TCP

◆ src

◆ tos

◆ ttl

◆ ver