pimd/pim6_mld_protocol.h

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * MLD protocol definitions
   4  * Copyright (C) 2022  David Lamparter for NetDEF, Inc.
   5  */
   6
   7 #ifndef _PIM6_MLD_PROTOCOL_H
   8 #define _PIM6_MLD_PROTOCOL_H
   9
  10 #include <stdalign.h>
  11 #include <stdint.h>
  12
  13 /* There is a struct icmp6_hdr provided by OS, but it includes 4 bytes of data.
  14  * Not helpful for us if we want to put the MLD struct after it.
  15  */
  16
  17 struct icmp6_plain_hdr {
  18         uint8_t icmp6_type;
  19         uint8_t icmp6_code;
  20         uint16_t icmp6_cksum;
  21 };
  22 static_assert(sizeof(struct icmp6_plain_hdr) == 4, "struct mismatch");
  23 static_assert(alignof(struct icmp6_plain_hdr) <= 4, "struct mismatch");
  24
  25 /* for MLDv1 query, report and leave all use the same packet format */
  26 struct mld_v1_pkt {
  27         uint16_t max_resp_code;
  28         uint16_t rsvd0;
  29         struct in6_addr grp;
  30 };
  31 static_assert(sizeof(struct mld_v1_pkt) == 20, "struct mismatch");
  32 static_assert(alignof(struct mld_v1_pkt) <= 4, "struct mismatch");
  33
  34
  35 struct mld_v2_query_hdr {
  36         uint16_t max_resp_code;
  37         uint16_t rsvd0;
  38         struct in6_addr grp;
  39         uint8_t flags;
  40         uint8_t qqic;
  41         uint16_t n_src;
  42         struct in6_addr srcs[0];
  43 };
  44 static_assert(sizeof(struct mld_v2_query_hdr) == 24, "struct mismatch");
  45 static_assert(alignof(struct mld_v2_query_hdr) <= 4, "struct mismatch");
  46
  47
  48 struct mld_v2_report_hdr {
  49         uint16_t rsvd;
  50         uint16_t n_records;
  51 };
  52 static_assert(sizeof(struct mld_v2_report_hdr) == 4, "struct mismatch");
  53 static_assert(alignof(struct mld_v2_report_hdr) <= 4, "struct mismatch");
  54
  55
  56 struct mld_v2_rec_hdr {
  57         uint8_t type;
  58         uint8_t aux_len;
  59         uint16_t n_src;
  60         struct in6_addr grp;
  61         struct in6_addr srcs[0];
  62 };
  63 static_assert(sizeof(struct mld_v2_rec_hdr) == 20, "struct mismatch");
  64 static_assert(alignof(struct mld_v2_rec_hdr) <= 4, "struct mismatch");
  65
  66 /* clang-format off */
  67 enum icmp6_mld_type {
  68         ICMP6_MLD_QUERY                 = 130,
  69         ICMP6_MLD_V1_REPORT             = 131,
  70         ICMP6_MLD_V1_DONE               = 132,
  71         ICMP6_MLD_V2_REPORT             = 143,
  72 };
  73
  74 enum mld_v2_rec_type {
  75         MLD_RECTYPE_IS_INCLUDE          = 1,
  76         MLD_RECTYPE_IS_EXCLUDE          = 2,
  77         MLD_RECTYPE_CHANGE_TO_INCLUDE   = 3,
  78         MLD_RECTYPE_CHANGE_TO_EXCLUDE   = 4,
  79         MLD_RECTYPE_ALLOW_NEW_SOURCES   = 5,
  80         MLD_RECTYPE_BLOCK_OLD_SOURCES   = 6,
  81 };
  82 /* clang-format on */
  83
  84 /* helper functions */
  85
  86 static inline unsigned int mld_max_resp_decode(uint16_t wire)
  87 {
  88         uint16_t code = ntohs(wire);
  89         uint8_t exp;
  90
  91         if (code < 0x8000)
  92                 return code;
  93         exp = (code >> 12) & 0x7;
  94         return ((code & 0xfff) | 0x1000) << (exp + 3);
  95 }
  96
  97 static inline uint16_t mld_max_resp_encode(uint32_t value)
  98 {
  99         uint16_t code;
 100         uint8_t exp;
 101
 102         if (value < 0x8000)
 103                 code = value;
 104         else {
 105                 exp = 16 - __builtin_clz(value);
 106                 code = (value >> (exp + 3)) & 0xfff;
 107                 code |= 0x8000 | (exp << 12);
 108         }
 109         return htons(code);
 110 }
 111
 112 #endif /* _PIM6_MLD_PROTOCOL_H */