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
ipv6_rpl_addr_decompress(struct in6_addr * dst,const struct in6_addr * daddr,const void * post,unsigned char pfx)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
ipv6_rpl_addr_compress(void * dst,const struct in6_addr * addr,unsigned char pfx)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
ipv6_rpl_segdata_pos(const struct ipv6_rpl_sr_hdr * hdr,int i)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
ipv6_rpl_srh_size(unsigned char n,unsigned char cmpri,unsigned char cmpre)32 size_t ipv6_rpl_srh_size(unsigned char n, unsigned char cmpri,
33 unsigned char cmpre)
34 {
35 return sizeof(struct ipv6_rpl_sr_hdr) + (n * IPV6_PFXTAIL_LEN(cmpri)) +
36 IPV6_PFXTAIL_LEN(cmpre);
37 }
38
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)39 void ipv6_rpl_srh_decompress(struct ipv6_rpl_sr_hdr *outhdr,
40 const struct ipv6_rpl_sr_hdr *inhdr,
41 const struct in6_addr *daddr, unsigned char n)
42 {
43 int i;
44
45 outhdr->nexthdr = inhdr->nexthdr;
46 outhdr->hdrlen = (((n + 1) * sizeof(struct in6_addr)) >> 3);
47 outhdr->pad = 0;
48 outhdr->type = inhdr->type;
49 outhdr->segments_left = inhdr->segments_left;
50 outhdr->cmpri = 0;
51 outhdr->cmpre = 0;
52
53 for (i = 0; i < n; i++)
54 ipv6_rpl_addr_decompress(&outhdr->rpl_segaddr[i], daddr,
55 ipv6_rpl_segdata_pos(inhdr, i),
56 inhdr->cmpri);
57
58 ipv6_rpl_addr_decompress(&outhdr->rpl_segaddr[n], daddr,
59 ipv6_rpl_segdata_pos(inhdr, n),
60 inhdr->cmpre);
61 }
62
ipv6_rpl_srh_calc_cmpri(const struct ipv6_rpl_sr_hdr * inhdr,const struct in6_addr * daddr,unsigned char n)63 static unsigned char ipv6_rpl_srh_calc_cmpri(const struct ipv6_rpl_sr_hdr *inhdr,
64 const struct in6_addr *daddr,
65 unsigned char n)
66 {
67 unsigned char plen;
68 int i;
69
70 for (plen = 0; plen < sizeof(*daddr); plen++) {
71 for (i = 0; i < n; i++) {
72 if (daddr->s6_addr[plen] !=
73 inhdr->rpl_segaddr[i].s6_addr[plen])
74 return plen;
75 }
76 }
77
78 return IPV6_RPL_BEST_ADDR_COMPRESSION;
79 }
80
ipv6_rpl_srh_calc_cmpre(const struct in6_addr * daddr,const struct in6_addr * last_segment)81 static unsigned char ipv6_rpl_srh_calc_cmpre(const struct in6_addr *daddr,
82 const struct in6_addr *last_segment)
83 {
84 unsigned int plen;
85
86 for (plen = 0; plen < sizeof(*daddr); plen++) {
87 if (daddr->s6_addr[plen] != last_segment->s6_addr[plen])
88 return plen;
89 }
90
91 return IPV6_RPL_BEST_ADDR_COMPRESSION;
92 }
93
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)94 void ipv6_rpl_srh_compress(struct ipv6_rpl_sr_hdr *outhdr,
95 const struct ipv6_rpl_sr_hdr *inhdr,
96 const struct in6_addr *daddr, unsigned char n)
97 {
98 unsigned char cmpri, cmpre;
99 size_t seglen;
100 int i;
101
102 cmpri = ipv6_rpl_srh_calc_cmpri(inhdr, daddr, n);
103 cmpre = ipv6_rpl_srh_calc_cmpre(daddr, &inhdr->rpl_segaddr[n]);
104
105 outhdr->nexthdr = inhdr->nexthdr;
106 seglen = (n * IPV6_PFXTAIL_LEN(cmpri)) + IPV6_PFXTAIL_LEN(cmpre);
107 outhdr->hdrlen = seglen >> 3;
108 if (seglen & 0x7) {
109 outhdr->hdrlen++;
110 outhdr->pad = 8 - (seglen & 0x7);
111 } else {
112 outhdr->pad = 0;
113 }
114 outhdr->type = inhdr->type;
115 outhdr->segments_left = inhdr->segments_left;
116 outhdr->cmpri = cmpri;
117 outhdr->cmpre = cmpre;
118
119 for (i = 0; i < n; i++)
120 ipv6_rpl_addr_compress(ipv6_rpl_segdata_pos(outhdr, i),
121 &inhdr->rpl_segaddr[i], cmpri);
122
123 ipv6_rpl_addr_compress(ipv6_rpl_segdata_pos(outhdr, n),
124 &inhdr->rpl_segaddr[n], cmpre);
125 }
126