ROHC CRC routines. More...

#include "crc.h"
#include "protocols/ip_numbers.h"
#include "protocols/ip.h"
#include "protocols/ipv4.h"
#include "protocols/ipv6.h"
#include "protocols/udp.h"
#include "protocols/rtp.h"
#include "protocols/esp.h"
#include "protocols/tcp.h"
#include <stdlib.h>
#include <assert.h>

Include dependency graph for crc.c:

Functions
static uint8_t	ipv6_ext_calc_crc_static (const uint8_t const ip, const rohc_crc_type_t crc_type, const uint8_t init_val, const uint8_t const crc_table)
	Compute the CRC-STATIC part of IPv6 extensions. More...

static uint8_t	ipv6_ext_calc_crc_dyn (const uint8_t const ip, const rohc_crc_type_t crc_type, const uint8_t init_val, const uint8_t const crc_table)
	Compute the CRC-DYNAMIC part of IPv6 extensions. More...

static uint8_t *	ipv6_get_first_extension (const uint8_t const ip, uint8_t const type)
	Get the first extension in an IPv6 packet. More...

static char	rohc_crc_get_polynom (const rohc_crc_type_t crc_type)
	Get the polynom for the given CRC type. More...

static uint8_t	crc_calc_8 (const uint8_t const buf, const size_t size, const uint8_t init_val, const uint8_t const crc_table)
	Optimized CRC-8 calculation using a table. More...

static uint8_t	crc_calc_7 (const uint8_t const buf, const size_t size, const uint8_t init_val, const uint8_t const crc_table)
	Optimized CRC-7 calculation using a table. More...

static uint8_t	crc_calc_3 (const uint8_t const buf, const size_t size, const uint8_t init_val, const uint8_t const crc_table)
	Optimized CRC-3 calculation using a table. More...

void	rohc_crc_init_table (uint8_t *const table, const rohc_crc_type_t crc_type)
	Initialize a CRC table given a 256-byte table and the CRC type to use. More...

uint8_t	crc_calculate (const rohc_crc_type_t crc_type, const uint8_t const data, const size_t length, const uint8_t init_val, const uint8_t const crc_table)
	Calculate the checksum for the given data. More...

uint32_t	crc_calc_fcs32 (const uint8_t *const data, const size_t length, const uint32_t init_val)
	Optimized CRC FCS-32 calculation using a table. More...

uint8_t	compute_crc_static (const uint8_t const outer_ip, const uint8_t const inner_ip, const uint8_t const next_header, const rohc_crc_type_t crc_type, const uint8_t init_val, const uint8_t const crc_table)
	Compute the CRC-STATIC part of an IP header. More...

uint8_t	compute_crc_dynamic (const uint8_t const outer_ip, const uint8_t const inner_ip, const uint8_t const next_header, const rohc_crc_type_t crc_type, const uint8_t init_val, const uint8_t const crc_table)
	Compute the CRC-DYNAMIC part of an IP header. More...

Variables
static const uint32_t	crc_table_fcs32 [256]
	The pre-computed table for 32-bit Frame Check Sequence (FCS) More...

Detailed Description

ROHC CRC routines.

Author: Didier Barvaux didie.nosp@m.r.ba.nosp@m.rvaux.nosp@m.@tou.nosp@m.louse.nosp@m..viv.nosp@m.eris..nosp@m.com; Didier Barvaux didie.nosp@m.r@ba.nosp@m.rvaux.nosp@m..org; FWX rohc_.nosp@m.team.nosp@m.@dial.nosp@m.ine..nosp@m.fr

Function Documentation

◆ compute_crc_dynamic()

uint8_t compute_crc_dynamic	(	const uint8_t *const	outer_ip,
		const uint8_t *const	inner_ip,
		const uint8_t *const	next_header,
		const rohc_crc_type_t	crc_type,
		const uint8_t	init_val,
		const uint8_t *const	crc_table
	)

Compute the CRC-DYNAMIC part of an IP header.

Concerned fields are:

bytes 3-4, 5-6, 11-12 in original IPv4 header
bytes 5-6 in original IPv6 header

Parameters

outer_ip	The outer IP packet
inner_ip	The inner IP packet if there is 2 IP headers, NULL otherwise
next_header	The next header located after the IP header(s)
crc_type	The type of CRC
init_val	The initial CRC value
crc_table	The pre-computed table for fast CRC computation

Returns: The checksum

◆ compute_crc_static()

uint8_t compute_crc_static	(	const uint8_t *const	outer_ip,
		const uint8_t *const	inner_ip,
		const uint8_t *const	next_header,
		const rohc_crc_type_t	crc_type,
		const uint8_t	init_val,
		const uint8_t *const	crc_table
	)

Compute the CRC-STATIC part of an IP header.

Concerned fields are: all fields expect those for CRC-DYNAMIC

bytes 1-2, 7-10, 13-20 in original IPv4 header
bytes 1-4, 7-40 in original IPv6 header

This function is one of the functions that must exist in one profile for the framework to work.

Parameters

outer_ip	The outer IP packet
inner_ip	The inner IP packet if there is 2 IP headers, NULL otherwise
next_header	The next header located after the IP header(s)
crc_type	The type of CRC
init_val	The initial CRC value
crc_table	The pre-computed table for fast CRC computation

Returns: The checksum

◆ crc_calc_3()

static uint8_t crc_calc_3	(	const uint8_t *const	buf,
		const size_t	size,
		const uint8_t	init_val,
		const uint8_t *const	crc_table
	)

inlinestatic

Optimized CRC-3 calculation using a table.

Parameters

buf	The data to compute the CRC for
size	The size of the data
init_val	The initial CRC value
crc_table	The pre-computed table for fast CRC computation

Returns: The CRC byte

◆ crc_calc_7()

static uint8_t crc_calc_7	(	const uint8_t *const	buf,
		const size_t	size,
		const uint8_t	init_val,
		const uint8_t *const	crc_table
	)

inlinestatic

Optimized CRC-7 calculation using a table.

Parameters

buf	The data to compute the CRC for
size	The size of the data
init_val	The initial CRC value
crc_table	The pre-computed table for fast CRC computation

Returns: The CRC byte

◆ crc_calc_8()

static uint8_t crc_calc_8	(	const uint8_t *const	buf,
		const size_t	size,
		const uint8_t	init_val,
		const uint8_t *const	crc_table
	)

inlinestatic

Optimized CRC-8 calculation using a table.

Parameters

buf	The data to compute the CRC for
size	The size of the data
init_val	The initial CRC value
crc_table	The pre-computed table for fast CRC computation

Returns: The CRC byte

◆ crc_calc_fcs32()

uint32_t crc_calc_fcs32	(	const uint8_t *const	data,
		const size_t	length,
		const uint32_t	init_val
	)

Optimized CRC FCS-32 calculation using a table.

Parameters

data	The data to compute the CRC for
length	The size of the data
init_val	The initial value of the CRC

Returns: The 32-bit CRC

◆ crc_calculate()

uint8_t crc_calculate	(	const rohc_crc_type_t	crc_type,
		const uint8_t *const	data,
		const size_t	length,
		const uint8_t	init_val,
		const uint8_t *const	crc_table
	)

Calculate the checksum for the given data.

Parameters

crc_type	The CRC type
data	The data to calculate the checksum on
length	The length of the data
init_val	The initial CRC value
crc_table	The pre-computed table for fast CRC computation

Returns: The checksum

◆ ipv6_ext_calc_crc_dyn()

static uint8_t ipv6_ext_calc_crc_dyn	(	const uint8_t *const	ip,
		const rohc_crc_type_t	crc_type,
		const uint8_t	init_val,
		const uint8_t *const	crc_table
	)

static

Compute the CRC-DYNAMIC part of IPv6 extensions.

Only entire AH header is concerned.

Parameters

ip	The IPv6 packet
crc_type	The type of CRC
init_val	The initial CRC value
crc_table	The pre-computed table for fast CRC computation

Returns: The checksum

◆ ipv6_ext_calc_crc_static()

static uint8_t ipv6_ext_calc_crc_static	(	const uint8_t *const	ip,
		const rohc_crc_type_t	crc_type,
		const uint8_t	init_val,
		const uint8_t *const	crc_table
	)

static

Compute the CRC-STATIC part of IPv6 extensions.

Prototypes of private functions

Private functions All extensions are concerned except entire AH header.

Parameters

ip	The IPv6 packet
crc_type	The type of CRC
init_val	The initial CRC value
crc_table	The pre-computed table for fast CRC computation

Returns: The checksum

◆ ipv6_get_first_extension()

static uint8_t * ipv6_get_first_extension	(	const uint8_t *const	ip,
		uint8_t *const	type
	)

static

Get the first extension in an IPv6 packet.

Parameters

ip	The IPv6 packet
type	The type of the extension

Returns: The extension, NULL if there is no extension

◆ rohc_crc_get_polynom()

static char rohc_crc_get_polynom ( const rohc_crc_type_t crc_type )

static

Get the polynom for the given CRC type.

Parameters

crc_type The CRC type

Returns: The polynom for the requested CRC type

◆ rohc_crc_init_table()

void rohc_crc_init_table	(	uint8_t *const	table,
		const rohc_crc_type_t	crc_type
	)

Initialize a CRC table given a 256-byte table and the CRC type to use.

Public functions

Parameters

table	IN/OUT: The 256-byte table to initialize
crc_type	The type of CRC to initialize the table for

Variable Documentation

◆ crc_table_fcs32

const uint32_t crc_table_fcs32[256]

static

The pre-computed table for 32-bit Frame Check Sequence (FCS)

x**0 + x**1 + x**2 + x**4 + x**5 + x**7 + x**8 + x**10 + x**11 + x**12 + x**16 + x**22 + x**23 + x**26 + x**32

Copied from RFC 1662, appendix C.3

Functions

Variables

Detailed Description

Function Documentation

◆ compute_crc_dynamic()

◆ compute_crc_static()

◆ crc_calc_3()

◆ crc_calc_7()

◆ crc_calc_8()

◆ crc_calc_fcs32()

◆ crc_calculate()

◆ ipv6_ext_calc_crc_dyn()

◆ ipv6_ext_calc_crc_static()

◆ ipv6_get_first_extension()

◆ rohc_crc_get_polynom()

◆ rohc_crc_init_table()

Variable Documentation

◆ crc_table_fcs32