285 lines
8.1 KiB
C
285 lines
8.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef LINUX_MLD_H
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#define LINUX_MLD_H
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#include <linux/in6.h>
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#include <linux/icmpv6.h>
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/* MLDv1 Query/Report/Done */
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struct mld_msg {
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struct icmp6hdr mld_hdr;
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struct in6_addr mld_mca;
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};
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#define mld_type mld_hdr.icmp6_type
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#define mld_code mld_hdr.icmp6_code
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#define mld_cksum mld_hdr.icmp6_cksum
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#define mld_maxdelay mld_hdr.icmp6_maxdelay
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#define mld_reserved mld_hdr.icmp6_dataun.un_data16[1]
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/* Multicast Listener Discovery version 2 headers */
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/* MLDv2 Report */
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struct mld2_grec {
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__u8 grec_type;
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__u8 grec_auxwords;
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__be16 grec_nsrcs;
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struct in6_addr grec_mca;
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struct in6_addr grec_src[];
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};
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struct mld2_report {
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struct icmp6hdr mld2r_hdr;
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struct mld2_grec mld2r_grec[];
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};
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#define mld2r_type mld2r_hdr.icmp6_type
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#define mld2r_resv1 mld2r_hdr.icmp6_code
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#define mld2r_cksum mld2r_hdr.icmp6_cksum
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#define mld2r_resv2 mld2r_hdr.icmp6_dataun.un_data16[0]
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#define mld2r_ngrec mld2r_hdr.icmp6_dataun.un_data16[1]
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/* MLDv2 Query */
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struct mld2_query {
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struct icmp6hdr mld2q_hdr;
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struct in6_addr mld2q_mca;
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#if defined(__LITTLE_ENDIAN_BITFIELD)
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__u8 mld2q_qrv:3,
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mld2q_suppress:1,
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mld2q_resv2:4;
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#elif defined(__BIG_ENDIAN_BITFIELD)
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__u8 mld2q_resv2:4,
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mld2q_suppress:1,
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mld2q_qrv:3;
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#else
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#error "Please fix <asm/byteorder.h>"
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#endif
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__u8 mld2q_qqic;
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__be16 mld2q_nsrcs;
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struct in6_addr mld2q_srcs[];
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};
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#define mld2q_type mld2q_hdr.icmp6_type
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#define mld2q_code mld2q_hdr.icmp6_code
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#define mld2q_cksum mld2q_hdr.icmp6_cksum
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#define mld2q_mrc mld2q_hdr.icmp6_maxdelay
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#define mld2q_resv1 mld2q_hdr.icmp6_dataun.un_data16[1]
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/* RFC3810, 5.1.3. Maximum Response Code:
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*
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* If Maximum Response Code >= 32768, Maximum Response Code represents a
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* floating-point value as follows:
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*
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* 0 1 2 3 4 5 6 7 8 9 A B C D E F
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* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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* |1| exp | mant |
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* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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*/
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#define MLDV2_MRC_EXP(value) (((value) >> 12) & 0x0007)
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#define MLDV2_MRC_MAN(value) ((value) & 0x0fff)
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/* RFC3810, 5.1.9. QQIC (Querier's Query Interval Code):
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*
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* If QQIC >= 128, QQIC represents a floating-point value as follows:
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*
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* 0 1 2 3 4 5 6 7
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* +-+-+-+-+-+-+-+-+
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* |1| exp | mant |
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* +-+-+-+-+-+-+-+-+
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*/
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#define MLDV2_QQIC_EXP(value) (((value) >> 4) & 0x07)
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#define MLDV2_QQIC_MAN(value) ((value) & 0x0f)
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/* MLDv2 QQIC floating-point exponential field min threshold */
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#define MLD_QQIC_MIN_THRESHOLD 128
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/* MLDv2 QQIC FP max threshold (mant = 0xF, exp = 7) -> 31744 */
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#define MLD_QQIC_MAX_THRESHOLD 31744
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/* MLDv2 MRC floating-point exponential field min threshold */
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#define MLD_MRC_MIN_THRESHOLD 32768UL
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/* MLDv2 MRC FP max threshold (mant = 0xFFF, exp = 7) -> 8387584 */
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#define MLD_MRC_MAX_THRESHOLD 8387584
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#define MLDV1_MRD_MAX_COMPAT (MLD_MRC_MIN_THRESHOLD - 1)
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#define MLD_MAX_QUEUE 8
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#define MLD_MAX_SKBS 32
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/* V2 exponential field encoding */
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/*
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* Calculate Maximum Response Code from Maximum Response Delay
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*
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* MRC represents the 16-bit encoded form of Maximum Response Delay (MRD);
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* once decoded, the resulting value is in milliseconds.
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*
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* RFC3810, 5.1.3. defines only the decoding formula:
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* Maximum Response Delay = (mant | 0x1000) << (exp + 3)
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*
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* but does NOT define the encoding procedure. To derive exponent:
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*
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* For the 16-bit MRC, the "hidden bit" (0x1000) is left shifted by 12 to
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* sit above the 12-bit mantissa. The RFC then shifts this entire block
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* left by (exp + 3) to reconstruct the value. So, 'hidden bit' is the
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* MSB which is shifted by (12 + exp + 3).
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*
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* Total left shift of the hidden bit = 12 + (exp + 3) = exp + 15.
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* This is the MSB at the 0-based bit position: (exp + 15).
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* Since fls() is 1-based, fls(value) - 1 = exp + 15.
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*
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* Therefore:
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* exp = fls(value) - 16
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* mant = (value >> (exp + 3)) & 0x0FFF
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*
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* Final encoding formula:
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* 0x8000 | (exp << 12) | mant
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*
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* Example (value = 1311744):
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* 0 1 2 3
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* 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
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* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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* |0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0| 1311744
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* | ^-^--------mant---------^ ^...(exp+3)...^| exp=5
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* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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*
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* Encoded:
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* 0x8000 | (5 << 12) | 0x404 = 0xD404
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*/
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static inline u16 mldv2_mrc(unsigned long mrd)
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{
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u16 mc_man, mc_exp;
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/* MRC < 32768 is literal */
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if (mrd < MLD_MRC_MIN_THRESHOLD)
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return mrd;
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/* Saturate at max representable (mant = 0xFFF, exp = 7) -> 8387584 */
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if (mrd >= MLD_MRC_MAX_THRESHOLD)
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return 0xFFFF;
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mc_exp = fls(mrd) - 16;
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mc_man = (mrd >> (mc_exp + 3)) & 0x0FFF;
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return 0x8000 | (mc_exp << 12) | mc_man;
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}
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/*
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* Calculate Querier's Query Interval Code from Querier's Query Interval
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*
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* QQIC represents the 8-bit encoded form of Querier's Query Interval (QQI);
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* once decoded, the resulting value is in seconds.
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*
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* RFC3810, 5.1.9. defines only the decoding formula:
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* QQI = (mant | 0x10) << (exp + 3)
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*
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* but does NOT define the encoding procedure. To derive exponent:
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*
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* For any value of mantissa and exponent, the decoding formula indicates
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* that the "hidden bit" (0x10) is shifted 4 bits left to sit above the
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* 4-bit mantissa. The RFC again shifts this entire block left by (exp + 3)
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* to reconstruct the value. So, 'hidden bit' is the MSB which is shifted
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* by (4 + exp + 3).
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*
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* Total left shift of the 'hidden bit' = 4 + (exp + 3) = exp + 7.
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* This is the MSB at the 0-based bit position: (exp + 7).
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* Since fls() is 1-based, fls(value) - 1 = exp + 7.
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*
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* Therefore:
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* exp = fls(value) - 8
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* mant = (value >> (exp + 3)) & 0x0F
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*
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* Final encoding formula:
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* 0x80 | (exp << 4) | mant
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*
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* Example (value = 3200):
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* 0 1
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* 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
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* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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* |0 0 0 0 1 1 0 0 1 0 0 0 0 0 0 0| (value = 3200)
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* | ^-^-mant^ ^..(exp+3)..^| exp = 4, mant = 9
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* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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*
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* Encoded:
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* 0x80 | (4 << 4) | 9 = 0xC9
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*/
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static inline u8 mldv2_qqic(unsigned long value)
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{
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u8 mc_man, mc_exp;
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/* QQIC < 128 is literal */
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if (value < MLD_QQIC_MIN_THRESHOLD)
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return value;
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/* Saturate at max representable (mant = 0xF, exp = 7) -> 31744 */
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if (value >= MLD_QQIC_MAX_THRESHOLD)
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return 0xFF;
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mc_exp = fls(value) - 8;
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mc_man = (value >> (mc_exp + 3)) & 0x0F;
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return 0x80 | (mc_exp << 4) | mc_man;
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}
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/* V2 exponential field decoding */
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/* Calculate Maximum Response Delay from Maximum Response Code
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*
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* RFC3810, relevant sections:
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* - 5.1.3. Maximum Response Code defines the decoding formula:
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* 0 1 2 3 4 5 6 7 8 9 A B C D E F
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* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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* |1| exp | mant |
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* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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* Maximum Response Delay = (mant | 0x1000) << (exp+3)
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* - 9.3. Query Response Interval
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*
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* After decode, MRC represents the Maximum Response Delay (MRD) in
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* units of milliseconds.
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*/
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static inline unsigned long mldv2_mrd(const struct mld2_query *mlh2)
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{
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unsigned long mc_mrc = ntohs(mlh2->mld2q_mrc);
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if (mc_mrc < MLD_MRC_MIN_THRESHOLD) {
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return mc_mrc;
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} else {
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unsigned long mc_man, mc_exp;
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mc_exp = MLDV2_MRC_EXP(mc_mrc);
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mc_man = MLDV2_MRC_MAN(mc_mrc);
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return (mc_man | 0x1000) << (mc_exp + 3);
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}
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}
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/* Calculate Querier's Query Interval from Querier's Query Interval Code
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*
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* RFC3810, relevant sections:
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* - 5.1.9. QQIC (Querier's Query Interval Code) defines the decoding formula:
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* 0 1 2 3 4 5 6 7
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* +-+-+-+-+-+-+-+-+
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* |1| exp | mant |
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* +-+-+-+-+-+-+-+-+
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* QQI = (mant | 0x10) << (exp + 3)
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* - 9.2. Query Interval
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* - 9.12. Older Version Querier Present Timeout
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* (the [Query Interval] in the last Query received)
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*
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* After decode, QQIC represents the Querier's Query Interval in units
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* of seconds.
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*/
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static inline unsigned long mldv2_qqi(const struct mld2_query *mlh2)
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{
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unsigned long qqic = mlh2->mld2q_qqic;
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if (qqic < MLD_QQIC_MIN_THRESHOLD) {
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return qqic;
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} else {
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unsigned long mc_man, mc_exp;
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mc_exp = MLDV2_QQIC_EXP(qqic);
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mc_man = MLDV2_QQIC_MAN(qqic);
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return (mc_man | 0x10) << (mc_exp + 3);
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}
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}
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#endif
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