linux/net/ipv6/ip6_checksum.c

// SPDX-License-Identifier: GPL-2.0
#include <net/ip.h>
#include <net/udp.h>
#include <net/udplite.h>
#include <asm/checksum.h>

#ifndef _HAVE_ARCH_IPV6_CSUM
__sum16 csum_ipv6_magic(const struct in6_addr *saddr,
			const struct in6_addr *daddr,
			__u32 len, __u8 proto, __wsum csum)
{

	int carry;
	__u32 ulen;
	__u32 uproto;
	__u32 sum = (__force u32)csum;

	sum += (__force u32)saddr->s6_addr32[0];
	carry = (sum < (__force u32)saddr->s6_addr32[0]);
	sum += carry;

	sum += (__force u32)saddr->s6_addr32[1];
	carry = (sum < (__force u32)saddr->s6_addr32[1]);
	sum += carry;

	sum += (__force u32)saddr->s6_addr32[2];
	carry = (sum < (__force u32)saddr->s6_addr32[2]);
	sum += carry;

	sum += (__force u32)saddr->s6_addr32[3];
	carry = (sum < (__force u32)saddr->s6_addr32[3]);
	sum += carry;

	sum += (__force u32)daddr->s6_addr32[0];
	carry = (sum < (__force u32)daddr->s6_addr32[0]);
	sum += carry;

	sum += (__force u32)daddr->s6_addr32[1];
	carry = (sum < (__force u32)daddr->s6_addr32[1]);
	sum += carry;

	sum += (__force u32)daddr->s6_addr32[2];
	carry = (sum < (__force u32)daddr->s6_addr32[2]);
	sum += carry;

	sum += (__force u32)daddr->s6_addr32[3];
	carry = (sum < (__force u32)daddr->s6_addr32[3]);
	sum += carry;

	ulen = (__force u32)htonl((__u32) len);
	sum += ulen;
	carry = (sum < ulen);
	sum += carry;

	uproto = (__force u32)htonl(proto);
	sum += uproto;
	carry = (sum < uproto);
	sum += carry;

	return csum_fold((__force __wsum)sum);
}
EXPORT_SYMBOL(csum_ipv6_magic);
#endif

int udp6_csum_init(struct sk_buff *skb, struct udphdr *uh, int proto)
{ … }
EXPORT_SYMBOL(…);

/* Function to set UDP checksum for an IPv6 UDP packet. This is intended
 * for the simple case like when setting the checksum for a UDP tunnel.
 */
void udp6_set_csum(bool nocheck, struct sk_buff *skb,
		   const struct in6_addr *saddr,
		   const struct in6_addr *daddr, int len)
{ … }
EXPORT_SYMBOL(…);