root/include/net/mld.h

DEFINITIONS

1. mldv2_mrc

#ifndef LINUX_MLD_H
#define LINUX_MLD_H

#include <linux/in6.h>
#include <linux/icmpv6.h>

/* MLDv1 Query/Report/Done */
struct mld_msg {
        struct icmp6hdr         mld_hdr;
        struct in6_addr         mld_mca;
};

#define mld_type                mld_hdr.icmp6_type
#define mld_code                mld_hdr.icmp6_code
#define mld_cksum               mld_hdr.icmp6_cksum
#define mld_maxdelay            mld_hdr.icmp6_maxdelay
#define mld_reserved            mld_hdr.icmp6_dataun.un_data16[1]

/* Multicast Listener Discovery version 2 headers */
/* MLDv2 Report */
struct mld2_grec {
        __u8            grec_type;
        __u8            grec_auxwords;
        __be16          grec_nsrcs;
        struct in6_addr grec_mca;
        struct in6_addr grec_src[0];
};

struct mld2_report {
        struct icmp6hdr         mld2r_hdr;
        struct mld2_grec        mld2r_grec[0];
};

#define mld2r_type              mld2r_hdr.icmp6_type
#define mld2r_resv1             mld2r_hdr.icmp6_code
#define mld2r_cksum             mld2r_hdr.icmp6_cksum
#define mld2r_resv2             mld2r_hdr.icmp6_dataun.un_data16[0]
#define mld2r_ngrec             mld2r_hdr.icmp6_dataun.un_data16[1]

/* MLDv2 Query */
struct mld2_query {
        struct icmp6hdr         mld2q_hdr;
        struct in6_addr         mld2q_mca;
#if defined(__LITTLE_ENDIAN_BITFIELD)
        __u8                    mld2q_qrv:3,
                                mld2q_suppress:1,
                                mld2q_resv2:4;
#elif defined(__BIG_ENDIAN_BITFIELD)
        __u8                    mld2q_resv2:4,
                                mld2q_suppress:1,
                                mld2q_qrv:3;
#else
#error "Please fix <asm/byteorder.h>"
#endif
        __u8                    mld2q_qqic;
        __be16                  mld2q_nsrcs;
        struct in6_addr         mld2q_srcs[0];
};

#define mld2q_type              mld2q_hdr.icmp6_type
#define mld2q_code              mld2q_hdr.icmp6_code
#define mld2q_cksum             mld2q_hdr.icmp6_cksum
#define mld2q_mrc               mld2q_hdr.icmp6_maxdelay
#define mld2q_resv1             mld2q_hdr.icmp6_dataun.un_data16[1]

/* RFC3810, 5.1.3. Maximum Response Code:
 *
 * If Maximum Response Code >= 32768, Maximum Response Code represents a
 * floating-point value as follows:
 *
 *  0 1 2 3 4 5 6 7 8 9 A B C D E F
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |1| exp |          mant         |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 */
#define MLDV2_MRC_EXP(value)    (((value) >> 12) & 0x0007)
#define MLDV2_MRC_MAN(value)    ((value) & 0x0fff)

/* RFC3810, 5.1.9. QQIC (Querier's Query Interval Code):
 *
 * If QQIC >= 128, QQIC represents a floating-point value as follows:
 *
 *  0 1 2 3 4 5 6 7
 * +-+-+-+-+-+-+-+-+
 * |1| exp | mant  |
 * +-+-+-+-+-+-+-+-+
 */
#define MLDV2_QQIC_EXP(value)   (((value) >> 4) & 0x07)
#define MLDV2_QQIC_MAN(value)   ((value) & 0x0f)

#define MLD_EXP_MIN_LIMIT       32768UL
#define MLDV1_MRD_MAX_COMPAT    (MLD_EXP_MIN_LIMIT - 1)

static inline unsigned long mldv2_mrc(const struct mld2_query *mlh2)
{
        /* RFC3810, 5.1.3. Maximum Response Code */
        unsigned long ret, mc_mrc = ntohs(mlh2->mld2q_mrc);

        if (mc_mrc < MLD_EXP_MIN_LIMIT) {
                ret = mc_mrc;
        } else {
                unsigned long mc_man, mc_exp;

                mc_exp = MLDV2_MRC_EXP(mc_mrc);
                mc_man = MLDV2_MRC_MAN(mc_mrc);

                ret = (mc_man | 0x1000) << (mc_exp + 3);
        }

        return ret;
}

#endif