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(dst: &outhdr->rpl_segaddr[i], daddr, |
48 | post: ipv6_rpl_segdata_pos(hdr: inhdr, i), |
49 | pfx: inhdr->cmpri); |
50 | |
51 | ipv6_rpl_addr_decompress(dst: &outhdr->rpl_segaddr[n], daddr, |
52 | post: ipv6_rpl_segdata_pos(hdr: inhdr, i: n), |
53 | pfx: 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, last_segment: &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(dst: ipv6_rpl_segdata_pos(hdr: outhdr, i), |
114 | addr: &inhdr->rpl_segaddr[i], pfx: cmpri); |
115 | |
116 | ipv6_rpl_addr_compress(dst: ipv6_rpl_segdata_pos(hdr: outhdr, i: n), |
117 | addr: &inhdr->rpl_segaddr[n], pfx: cmpre); |
118 | } |
119 | |