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 #define IPV6_RPL_BEST_ADDR_COMPRESSION 15
12
13 static void ipv6_rpl_addr_decompress(struct in6_addr *dst,
14 const struct in6_addr *daddr,
15 const void *post, unsigned char pfx)
16 {
17 memcpy(dst, daddr, pfx);
18 memcpy(&dst->s6_addr[pfx], post, IPV6_PFXTAIL_LEN(pfx));
19 }
20
21 static void ipv6_rpl_addr_compress(void *dst, const struct in6_addr *addr,
22 unsigned char pfx)
23 {
24 memcpy(dst, &addr->s6_addr[pfx], IPV6_PFXTAIL_LEN(pfx));
25 }
26
27 static void *ipv6_rpl_segdata_pos(const struct ipv6_rpl_sr_hdr *hdr, int i)
28 {
29 return (void *)&hdr->rpl_segdata[i * IPV6_PFXTAIL_LEN(hdr->cmpri)];
30 }
31
32 void ipv6_rpl_srh_decompress(struct ipv6_rpl_sr_hdr *outhdr,
33 const struct ipv6_rpl_sr_hdr *inhdr,
34 const struct in6_addr *daddr, unsigned char n)
35 {
36 int i;
37
38 outhdr->nexthdr = inhdr->nexthdr;
39 outhdr->hdrlen = (((n + 1) * sizeof(struct in6_addr)) >> 3);
40 outhdr->pad = 0;
41 outhdr->type = inhdr->type;
42 outhdr->segments_left = inhdr->segments_left;
43 outhdr->cmpri = 0;
44 outhdr->cmpre = 0;
45
46 for (i = 0; i < n; i++)
47 ipv6_rpl_addr_decompress(&outhdr->rpl_segaddr[i], daddr,
48 ipv6_rpl_segdata_pos(inhdr, i),
49 inhdr->cmpri);
50
51 ipv6_rpl_addr_decompress(&outhdr->rpl_segaddr[n], daddr,
52 ipv6_rpl_segdata_pos(inhdr, n),
53 inhdr->cmpre);
54 }
55
56 static unsigned char ipv6_rpl_srh_calc_cmpri(const struct ipv6_rpl_sr_hdr *inhdr,
57 const struct in6_addr *daddr,
58 unsigned char n)
59 {
60 unsigned char plen;
61 int i;
62
63 for (plen = 0; plen < sizeof(*daddr); plen++) {
64 for (i = 0; i < n; i++) {
65 if (daddr->s6_addr[plen] !=
66 inhdr->rpl_segaddr[i].s6_addr[plen])
67 return plen;
68 }
69 }
70
71 return IPV6_RPL_BEST_ADDR_COMPRESSION;
72 }
73
74 static unsigned char ipv6_rpl_srh_calc_cmpre(const struct in6_addr *daddr,
75 const struct in6_addr *last_segment)
76 {
77 unsigned int plen;
78
79 for (plen = 0; plen < sizeof(*daddr); plen++) {
80 if (daddr->s6_addr[plen] != last_segment->s6_addr[plen])
81 return plen;
82 }
83
84 return IPV6_RPL_BEST_ADDR_COMPRESSION;
85 }
86
87 void ipv6_rpl_srh_compress(struct ipv6_rpl_sr_hdr *outhdr,
88 const struct ipv6_rpl_sr_hdr *inhdr,
89 const struct in6_addr *daddr, unsigned char n)
90 {
91 unsigned char cmpri, cmpre;
92 size_t seglen;
93 int i;
94
95 cmpri = ipv6_rpl_srh_calc_cmpri(inhdr, daddr, n);
96 cmpre = ipv6_rpl_srh_calc_cmpre(daddr, &inhdr->rpl_segaddr[n]);
97
98 outhdr->nexthdr = inhdr->nexthdr;
99 seglen = (n * IPV6_PFXTAIL_LEN(cmpri)) + IPV6_PFXTAIL_LEN(cmpre);
100 outhdr->hdrlen = seglen >> 3;
101 if (seglen & 0x7) {
102 outhdr->hdrlen++;
103 outhdr->pad = 8 - (seglen & 0x7);
104 } else {
105 outhdr->pad = 0;
106 }
107 outhdr->type = inhdr->type;
108 outhdr->segments_left = inhdr->segments_left;
109 outhdr->cmpri = cmpri;
110 outhdr->cmpre = cmpre;
111
112 for (i = 0; i < n; i++)
113 ipv6_rpl_addr_compress(ipv6_rpl_segdata_pos(outhdr, i),
114 &inhdr->rpl_segaddr[i], cmpri);
115
116 ipv6_rpl_addr_compress(ipv6_rpl_segdata_pos(outhdr, n),
117 &inhdr->rpl_segaddr[n], cmpre);
118 }
119
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