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1// SPDX-License-Identifier: GPL-2.0-only
2/**
3 * Authors:
4 * (C) 2020 Alexander Aring <alex.aring@gmail.com>
5 */
6
7#include <net/ipv6.h>
8#include <net/rpl.h>
9
10#define IPV6_PFXTAIL_LEN(x) (sizeof(struct in6_addr) - (x))
11
12static void ipv6_rpl_addr_decompress(struct in6_addr *dst,
13 const struct in6_addr *daddr,
14 const void *post, unsigned char pfx)
15{
16 memcpy(dst, daddr, pfx);
17 memcpy(&dst->s6_addr[pfx], post, IPV6_PFXTAIL_LEN(pfx));
18}
19
20static void ipv6_rpl_addr_compress(void *dst, const struct in6_addr *addr,
21 unsigned char pfx)
22{
23 memcpy(dst, &addr->s6_addr[pfx], IPV6_PFXTAIL_LEN(pfx));
24}
25
26static void *ipv6_rpl_segdata_pos(const struct ipv6_rpl_sr_hdr *hdr, int i)
27{
28 return (void *)&hdr->rpl_segdata[i * IPV6_PFXTAIL_LEN(hdr->cmpri)];
29}
30
31size_t ipv6_rpl_srh_size(unsigned char n, unsigned char cmpri,
32 unsigned char cmpre)
33{
34 return (n * IPV6_PFXTAIL_LEN(cmpri)) + IPV6_PFXTAIL_LEN(cmpre);
35}
36
37void ipv6_rpl_srh_decompress(struct ipv6_rpl_sr_hdr *outhdr,
38 const struct ipv6_rpl_sr_hdr *inhdr,
39 const struct in6_addr *daddr, unsigned char n)
40{
41 int i;
42
43 outhdr->nexthdr = inhdr->nexthdr;
44 outhdr->hdrlen = (((n + 1) * sizeof(struct in6_addr)) >> 3);
45 outhdr->pad = 0;
46 outhdr->type = inhdr->type;
47 outhdr->segments_left = inhdr->segments_left;
48 outhdr->cmpri = 0;
49 outhdr->cmpre = 0;
50
51 for (i = 0; i < n; i++)
52 ipv6_rpl_addr_decompress(&outhdr->rpl_segaddr[i], daddr,
53 ipv6_rpl_segdata_pos(inhdr, i),
54 inhdr->cmpri);
55
56 ipv6_rpl_addr_decompress(&outhdr->rpl_segaddr[n], daddr,
57 ipv6_rpl_segdata_pos(inhdr, n),
58 inhdr->cmpre);
59}
60
61static unsigned char ipv6_rpl_srh_calc_cmpri(const struct ipv6_rpl_sr_hdr *inhdr,
62 const struct in6_addr *daddr,
63 unsigned char n)
64{
65 unsigned char plen;
66 int i;
67
68 for (plen = 0; plen < sizeof(*daddr); plen++) {
69 for (i = 0; i < n; i++) {
70 if (daddr->s6_addr[plen] !=
71 inhdr->rpl_segaddr[i].s6_addr[plen])
72 return plen;
73 }
74 }
75
76 return plen;
77}
78
79static unsigned char ipv6_rpl_srh_calc_cmpre(const struct in6_addr *daddr,
80 const struct in6_addr *last_segment)
81{
82 unsigned int plen;
83
84 for (plen = 0; plen < sizeof(*daddr); plen++) {
85 if (daddr->s6_addr[plen] != last_segment->s6_addr[plen])
86 break;
87 }
88
89 return plen;
90}
91
92void ipv6_rpl_srh_compress(struct ipv6_rpl_sr_hdr *outhdr,
93 const struct ipv6_rpl_sr_hdr *inhdr,
94 const struct in6_addr *daddr, unsigned char n)
95{
96 unsigned char cmpri, cmpre;
97 size_t seglen;
98 int i;
99
100 cmpri = ipv6_rpl_srh_calc_cmpri(inhdr, daddr, n);
101 cmpre = ipv6_rpl_srh_calc_cmpre(daddr, &inhdr->rpl_segaddr[n]);
102
103 outhdr->nexthdr = inhdr->nexthdr;
104 seglen = (n * IPV6_PFXTAIL_LEN(cmpri)) + IPV6_PFXTAIL_LEN(cmpre);
105 outhdr->hdrlen = seglen >> 3;
106 if (seglen & 0x7) {
107 outhdr->hdrlen++;
108 outhdr->pad = 8 - (seglen & 0x7);
109 } else {
110 outhdr->pad = 0;
111 }
112 outhdr->type = inhdr->type;
113 outhdr->segments_left = inhdr->segments_left;
114 outhdr->cmpri = cmpri;
115 outhdr->cmpre = cmpre;
116
117 for (i = 0; i < n; i++)
118 ipv6_rpl_addr_compress(ipv6_rpl_segdata_pos(outhdr, i),
119 &inhdr->rpl_segaddr[i], cmpri);
120
121 ipv6_rpl_addr_compress(ipv6_rpl_segdata_pos(outhdr, n),
122 &inhdr->rpl_segaddr[n], cmpre);
123}