pimd/pim6_mld_protocol.h

   1 /*
   2  * MLD protocol definitions
   3  * Copyright (C) 2022  David Lamparter for NetDEF, Inc.
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by the Free
   7  * Software Foundation; either version 2 of the License, or (at your option)
   8  * any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; see the file COPYING; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  18  */
  19
  20 #ifndef _PIM6_MLD_PROTOCOL_H
  21 #define _PIM6_MLD_PROTOCOL_H
  22
  23 #include <stdalign.h>
  24 #include <stdint.h>
  25
  26 /* There is a struct icmp6_hdr provided by OS, but it includes 4 bytes of data.
  27  * Not helpful for us if we want to put the MLD struct after it.
  28  */
  29
  30 struct icmp6_plain_hdr {
  31         uint8_t icmp6_type;
  32         uint8_t icmp6_code;
  33         uint16_t icmp6_cksum;
  34 };
  35 static_assert(sizeof(struct icmp6_plain_hdr) == 4, "struct mismatch");
  36 static_assert(alignof(struct icmp6_plain_hdr) <= 4, "struct mismatch");
  37
  38 /* for MLDv1 query, report and leave all use the same packet format */
  39 struct mld_v1_pkt {
  40         uint16_t max_resp_code;
  41         uint16_t rsvd0;
  42         struct in6_addr grp;
  43 };
  44 static_assert(sizeof(struct mld_v1_pkt) == 20, "struct mismatch");
  45 static_assert(alignof(struct mld_v1_pkt) <= 4, "struct mismatch");
  46
  47
  48 struct mld_v2_query_hdr {
  49         uint16_t max_resp_code;
  50         uint16_t rsvd0;
  51         struct in6_addr grp;
  52         uint8_t flags;
  53         uint8_t qqic;
  54         uint16_t n_src;
  55         struct in6_addr srcs[0];
  56 };
  57 static_assert(sizeof(struct mld_v2_query_hdr) == 24, "struct mismatch");
  58 static_assert(alignof(struct mld_v2_query_hdr) <= 4, "struct mismatch");
  59
  60
  61 struct mld_v2_report_hdr {
  62         uint16_t rsvd;
  63         uint16_t n_records;
  64 };
  65 static_assert(sizeof(struct mld_v2_report_hdr) == 4, "struct mismatch");
  66 static_assert(alignof(struct mld_v2_report_hdr) <= 4, "struct mismatch");
  67
  68
  69 struct mld_v2_rec_hdr {
  70         uint8_t type;
  71         uint8_t aux_len;
  72         uint16_t n_src;
  73         struct in6_addr grp;
  74         struct in6_addr srcs[0];
  75 };
  76 static_assert(sizeof(struct mld_v2_rec_hdr) == 20, "struct mismatch");
  77 static_assert(alignof(struct mld_v2_rec_hdr) <= 4, "struct mismatch");
  78
  79 /* clang-format off */
  80 enum icmp6_mld_type {
  81         ICMP6_MLD_QUERY                 = 130,
  82         ICMP6_MLD_V1_REPORT             = 131,
  83         ICMP6_MLD_V1_DONE               = 132,
  84         ICMP6_MLD_V2_REPORT             = 143,
  85 };
  86
  87 enum mld_v2_rec_type {
  88         MLD_RECTYPE_IS_INCLUDE          = 1,
  89         MLD_RECTYPE_IS_EXCLUDE          = 2,
  90         MLD_RECTYPE_CHANGE_TO_INCLUDE   = 3,
  91         MLD_RECTYPE_CHANGE_TO_EXCLUDE   = 4,
  92         MLD_RECTYPE_ALLOW_NEW_SOURCES   = 5,
  93         MLD_RECTYPE_BLOCK_OLD_SOURCES   = 6,
  94 };
  95 /* clang-format on */
  96
  97 /* helper functions */
  98
  99 static inline unsigned int mld_max_resp_decode(uint16_t wire)
 100 {
 101         uint16_t code = ntohs(wire);
 102         uint8_t exp;
 103
 104         if (code < 0x8000)
 105                 return code;
 106         exp = (code >> 12) & 0x7;
 107         return ((code & 0xfff) | 0x1000) << (exp + 3);
 108 }
 109
 110 static inline uint16_t mld_max_resp_encode(uint32_t value)
 111 {
 112         uint16_t code;
 113         uint8_t exp;
 114
 115         if (value < 0x8000)
 116                 code = value;
 117         else {
 118                 exp = 16 - __builtin_clz(value);
 119                 code = (value >> (exp + 3)) & 0xfff;
 120                 code |= 0x8000 | (exp << 12);
 121         }
 122         return htons(code);
 123 }
 124
 125 #endif /* _PIM6_MLD_PROTOCOL_H */