inet_chksum.c File Reference

#include "lwip/opt.h"
#include "lwip/inet_chksum.h"
#include "lwip/def.h"
#include "lwip/ip_addr.h"
#include <string.h>

Functions
u16_t	ip6_chksum_pseudo (struct pbuf *p, u8_t proto, u16_t proto_len, const ip6_addr_t *src, const ip6_addr_t *dest)
u16_t	ip6_chksum_pseudo_partial (struct pbuf *p, u8_t proto, u16_t proto_len, u16_t chksum_len, const ip6_addr_t *src, const ip6_addr_t *dest)
u16_t	inet_chksum_pbuf (struct pbuf *p)

Detailed Description

Internet checksum functions.
These are some reference implementations of the checksum algorithm, with the aim of being simple, correct and fully portable. Checksumming is the first thing you would want to optimize for your platform. If you create your own version, link it in and in your cc.h put:

#define LWIP_CHKSUM your_checksum_routine

Or you can select from the implementations below by defining LWIP_CHKSUM_ALGORITHM to 1, 2 or 3.

Function Documentation

inet_chksum_pbuf()

u16_t inet_chksum_pbuf

(

struct pbuf *

p

)

Calculate a checksum over a chain of pbufs (without pseudo-header, much like inet_chksum only pbufs are used).

Parameters

p	pbuf chain over that the checksum should be calculated

Returns

checksum (as u16_t) to be saved directly in the protocol header

ip6_chksum_pseudo()

u16_t ip6_chksum_pseudo	(	struct pbuf *	p,
		u8_t	proto,
		u16_t	proto_len,
		const ip6_addr_t *	src,
		const ip6_addr_t *	dest
	)

Calculates the checksum with IPv6 pseudo header used by TCP and UDP for a pbuf chain. IPv6 addresses are expected to be in network byte order.

Parameters

p	chain of pbufs over that a checksum should be calculated (ip data part)
proto	ipv6 protocol/next header (used for checksum of pseudo header)
proto_len	length of the ipv6 payload (used for checksum of pseudo header)
src	source ipv6 address (used for checksum of pseudo header)
dest	destination ipv6 address (used for checksum of pseudo header)

Returns

checksum (as u16_t) to be saved directly in the protocol header

ip6_chksum_pseudo_partial()

u16_t ip6_chksum_pseudo_partial	(	struct pbuf *	p,
		u8_t	proto,
		u16_t	proto_len,
		u16_t	chksum_len,
		const ip6_addr_t *	src,
		const ip6_addr_t *	dest
	)

Calculates the checksum with IPv6 pseudo header used by TCP and UDP for a pbuf chain. IPv6 addresses are expected to be in network byte order. Will only compute for a portion of the payload.

Parameters

p	chain of pbufs over that a checksum should be calculated (ip data part)
proto	ipv6 protocol/next header (used for checksum of pseudo header)
proto_len	length of the ipv6 payload (used for checksum of pseudo header)
chksum_len	number of payload bytes used to compute chksum
src	source ipv6 address (used for checksum of pseudo header)
dest	destination ipv6 address (used for checksum of pseudo header)

Returns

checksum (as u16_t) to be saved directly in the protocol header