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 size_t ipv6_rpl_srh_size(unsigned char n, unsigned char cmpri,
33 unsigned char cmpre)
34 {
35 return (n * IPV6_PFXTAIL_LEN(cmpri)) + IPV6_PFXTAIL_LEN(cmpre);
36 }
37
38 void ipv6_rpl_srh_decompress(struct ipv6_rpl_sr_hdr *outhdr,
39 const struct ipv6_rpl_sr_hdr *inhdr,
40 const struct in6_addr *daddr, unsigned char n)
41 {
42 int i;
43
44 outhdr->nexthdr = inhdr->nexthdr;
45 outhdr->hdrlen = (((n + 1) * sizeof(struct in6_addr)) >> 3);
46 outhdr->pad = 0;
47 outhdr->type = inhdr->type;
48 outhdr->segments_left = inhdr->segments_left;
49 outhdr->cmpri = 0;
50 outhdr->cmpre = 0;
51
52 for (i = 0; i < n; i++)
53 ipv6_rpl_addr_decompress(&outhdr->rpl_segaddr[i], daddr,
54 ipv6_rpl_segdata_pos(inhdr, i),
55 inhdr->cmpri);
56
57 ipv6_rpl_addr_decompress(&outhdr->rpl_segaddr[n], daddr,
58 ipv6_rpl_segdata_pos(inhdr, n),
59 inhdr->cmpre);
60 }
61
62 static unsigned char ipv6_rpl_srh_calc_cmpri(const struct ipv6_rpl_sr_hdr *inhdr,
63 const struct in6_addr *daddr,
64 unsigned char n)
65 {
66 unsigned char plen;
67 int i;
68
69 for (plen = 0; plen < sizeof(*daddr); plen++) {
70 for (i = 0; i < n; i++) {
71 if (daddr->s6_addr[plen] !=
72 inhdr->rpl_segaddr[i].s6_addr[plen])
73 return plen;
74 }
75 }
76
77 return IPV6_RPL_BEST_ADDR_COMPRESSION;
78 }
79
80 static unsigned char ipv6_rpl_srh_calc_cmpre(const struct in6_addr *daddr,
81 const struct in6_addr *last_segment)
82 {
83 unsigned int plen;
84
85 for (plen = 0; plen < sizeof(*daddr); plen++) {
86 if (daddr->s6_addr[plen] != last_segment->s6_addr[plen])
87 return plen;
88 }
89
90 return IPV6_RPL_BEST_ADDR_COMPRESSION;
91 }
92
93 void ipv6_rpl_srh_compress(struct ipv6_rpl_sr_hdr *outhdr,
94 const struct ipv6_rpl_sr_hdr *inhdr,
95 const struct in6_addr *daddr, unsigned char n)
96 {
97 unsigned char cmpri, cmpre;
98 size_t seglen;
99 int i;
100
101 cmpri = ipv6_rpl_srh_calc_cmpri(inhdr, daddr, n);
102 cmpre = ipv6_rpl_srh_calc_cmpre(daddr, &inhdr->rpl_segaddr[n]);
103
104 outhdr->nexthdr = inhdr->nexthdr;
105 seglen = (n * IPV6_PFXTAIL_LEN(cmpri)) + IPV6_PFXTAIL_LEN(cmpre);
106 outhdr->hdrlen = seglen >> 3;
107 if (seglen & 0x7) {
108 outhdr->hdrlen++;
109 outhdr->pad = 8 - (seglen & 0x7);
110 } else {
111 outhdr->pad = 0;
112 }
113 outhdr->type = inhdr->type;
114 outhdr->segments_left = inhdr->segments_left;
115 outhdr->cmpri = cmpri;
116 outhdr->cmpre = cmpre;
117
118 for (i = 0; i < n; i++)
119 ipv6_rpl_addr_compress(ipv6_rpl_segdata_pos(outhdr, i),
120 &inhdr->rpl_segaddr[i], cmpri);
121
122 ipv6_rpl_addr_compress(ipv6_rpl_segdata_pos(outhdr, n),
123 &inhdr->rpl_segaddr[n], cmpre);
124 }
125
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