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// SPDX-License-Identifier: GPL-2.0-only
/*
* Authors:
* (C) 2020 Alexander Aring <alex.aring@gmail.com>
*/
#include <net/ipv6.h>
#include <net/rpl.h>
#define IPV6_PFXTAIL_LEN(x) (sizeof(struct in6_addr) - (x))
#define IPV6_RPL_BEST_ADDR_COMPRESSION 15
static void ipv6_rpl_addr_decompress(struct in6_addr *dst,
const struct in6_addr *daddr,
const void *post, unsigned char pfx)
{
memcpy(dst, daddr, pfx);
memcpy(&dst->s6_addr[pfx], post, IPV6_PFXTAIL_LEN(pfx));
}
static void ipv6_rpl_addr_compress(void *dst, const struct in6_addr *addr,
unsigned char pfx)
{
memcpy(dst, &addr->s6_addr[pfx], IPV6_PFXTAIL_LEN(pfx));
}
static void *ipv6_rpl_segdata_pos(const struct ipv6_rpl_sr_hdr *hdr, int i)
{
return (void *)&hdr->rpl_segdata[i * IPV6_PFXTAIL_LEN(hdr->cmpri)];
}
void ipv6_rpl_srh_decompress(struct ipv6_rpl_sr_hdr *outhdr,
const struct ipv6_rpl_sr_hdr *inhdr,
const struct in6_addr *daddr, unsigned char n)
{
int i;
outhdr->nexthdr = inhdr->nexthdr;
outhdr->hdrlen = (((n + 1) * sizeof(struct in6_addr)) >> 3);
outhdr->pad = 0;
outhdr->type = inhdr->type;
outhdr->segments_left = inhdr->segments_left;
outhdr->cmpri = 0;
outhdr->cmpre = 0;
for (i = 0; i < n; i++)
ipv6_rpl_addr_decompress(&outhdr->rpl_segaddr[i], daddr,
ipv6_rpl_segdata_pos(inhdr, i),
inhdr->cmpri);
ipv6_rpl_addr_decompress(&outhdr->rpl_segaddr[n], daddr,
ipv6_rpl_segdata_pos(inhdr, n),
inhdr->cmpre);
}
static unsigned char ipv6_rpl_srh_calc_cmpri(const struct ipv6_rpl_sr_hdr *inhdr,
const struct in6_addr *daddr,
unsigned char n)
{
unsigned char plen;
int i;
for (plen = 0; plen < sizeof(*daddr); plen++) {
for (i = 0; i < n; i++) {
if (daddr->s6_addr[plen] !=
inhdr->rpl_segaddr[i].s6_addr[plen])
return plen;
}
}
return IPV6_RPL_BEST_ADDR_COMPRESSION;
}
static unsigned char ipv6_rpl_srh_calc_cmpre(const struct in6_addr *daddr,
const struct in6_addr *last_segment)
{
unsigned int plen;
for (plen = 0; plen < sizeof(*daddr); plen++) {
if (daddr->s6_addr[plen] != last_segment->s6_addr[plen])
return plen;
}
return IPV6_RPL_BEST_ADDR_COMPRESSION;
}
void ipv6_rpl_srh_compress(struct ipv6_rpl_sr_hdr *outhdr,
const struct ipv6_rpl_sr_hdr *inhdr,
const struct in6_addr *daddr, unsigned char n)
{
unsigned char cmpri, cmpre;
size_t seglen;
int i;
cmpri = ipv6_rpl_srh_calc_cmpri(inhdr, daddr, n);
cmpre = ipv6_rpl_srh_calc_cmpre(daddr, &inhdr->rpl_segaddr[n]);
outhdr->nexthdr = inhdr->nexthdr;
seglen = (n * IPV6_PFXTAIL_LEN(cmpri)) + IPV6_PFXTAIL_LEN(cmpre);
outhdr->hdrlen = seglen >> 3;
if (seglen & 0x7) {
outhdr->hdrlen++;
outhdr->pad = 8 - (seglen & 0x7);
} else {
outhdr->pad = 0;
}
outhdr->type = inhdr->type;
outhdr->segments_left = inhdr->segments_left;
outhdr->cmpri = cmpri;
outhdr->cmpre = cmpre;
for (i = 0; i < n; i++)
ipv6_rpl_addr_compress(ipv6_rpl_segdata_pos(outhdr, i),
&inhdr->rpl_segaddr[i], cmpri);
ipv6_rpl_addr_compress(ipv6_rpl_segdata_pos(outhdr, n),
&inhdr->rpl_segaddr[n], cmpre);
}
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