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