/* SPDX-License-Identifier: GPL-2.0 */ #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[]; }; struct mld2_report { struct icmp6hdr mld2r_hdr; struct mld2_grec mld2r_grec[]; }; #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[]; }; #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) /* MLDv2 QQIC floating-point exponential field min threshold */ #define MLD_QQIC_MIN_THRESHOLD 128 /* MLDv2 QQIC FP max threshold (mant = 0xF, exp = 7) -> 31744 */ #define MLD_QQIC_MAX_THRESHOLD 31744 /* MLDv2 MRC floating-point exponential field min threshold */ #define MLD_MRC_MIN_THRESHOLD 32768UL /* MLDv2 MRC FP max threshold (mant = 0xFFF, exp = 7) -> 8387584 */ #define MLD_MRC_MAX_THRESHOLD 8387584 #define MLDV1_MRD_MAX_COMPAT (MLD_MRC_MIN_THRESHOLD - 1) #define MLD_MAX_QUEUE 8 #define MLD_MAX_SKBS 32 /* V2 exponential field encoding */ /* * Calculate Maximum Response Code from Maximum Response Delay * * MRC represents the 16-bit encoded form of Maximum Response Delay (MRD); * once decoded, the resulting value is in milliseconds. * * RFC3810, 5.1.3. defines only the decoding formula: * Maximum Response Delay = (mant | 0x1000) << (exp + 3) * * but does NOT define the encoding procedure. To derive exponent: * * For the 16-bit MRC, the "hidden bit" (0x1000) is left shifted by 12 to * sit above the 12-bit mantissa. The RFC then shifts this entire block * left by (exp + 3) to reconstruct the value. So, 'hidden bit' is the * MSB which is shifted by (12 + exp + 3). * * Total left shift of the hidden bit = 12 + (exp + 3) = exp + 15. * This is the MSB at the 0-based bit position: (exp + 15). * Since fls() is 1-based, fls(value) - 1 = exp + 15. * * Therefore: * exp = fls(value) - 16 * mant = (value >> (exp + 3)) & 0x0FFF * * Final encoding formula: * 0x8000 | (exp << 12) | mant * * Example (value = 1311744): * 0 1 2 3 * 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 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * |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 * | ^-^--------mant---------^ ^...(exp+3)...^| exp=5 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * * Encoded: * 0x8000 | (5 << 12) | 0x404 = 0xD404 */ static inline u16 mldv2_mrc(unsigned long mrd) { u16 mc_man, mc_exp; /* MRC < 32768 is literal */ if (mrd < MLD_MRC_MIN_THRESHOLD) return mrd; /* Saturate at max representable (mant = 0xFFF, exp = 7) -> 8387584 */ if (mrd >= MLD_MRC_MAX_THRESHOLD) return 0xFFFF; mc_exp = fls(mrd) - 16; mc_man = (mrd >> (mc_exp + 3)) & 0x0FFF; return 0x8000 | (mc_exp << 12) | mc_man; } /* * Calculate Querier's Query Interval Code from Querier's Query Interval * * QQIC represents the 8-bit encoded form of Querier's Query Interval (QQI); * once decoded, the resulting value is in seconds. * * RFC3810, 5.1.9. defines only the decoding formula: * QQI = (mant | 0x10) << (exp + 3) * * but does NOT define the encoding procedure. To derive exponent: * * For any value of mantissa and exponent, the decoding formula indicates * that the "hidden bit" (0x10) is shifted 4 bits left to sit above the * 4-bit mantissa. The RFC again shifts this entire block left by (exp + 3) * to reconstruct the value. So, 'hidden bit' is the MSB which is shifted * by (4 + exp + 3). * * Total left shift of the 'hidden bit' = 4 + (exp + 3) = exp + 7. * This is the MSB at the 0-based bit position: (exp + 7). * Since fls() is 1-based, fls(value) - 1 = exp + 7. * * Therefore: * exp = fls(value) - 8 * mant = (value >> (exp + 3)) & 0x0F * * Final encoding formula: * 0x80 | (exp << 4) | mant * * Example (value = 3200): * 0 1 * 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * |0 0 0 0 1 1 0 0 1 0 0 0 0 0 0 0| (value = 3200) * | ^-^-mant^ ^..(exp+3)..^| exp = 4, mant = 9 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * * Encoded: * 0x80 | (4 << 4) | 9 = 0xC9 */ static inline u8 mldv2_qqic(unsigned long value) { u8 mc_man, mc_exp; /* QQIC < 128 is literal */ if (value < MLD_QQIC_MIN_THRESHOLD) return value; /* Saturate at max representable (mant = 0xF, exp = 7) -> 31744 */ if (value >= MLD_QQIC_MAX_THRESHOLD) return 0xFF; mc_exp = fls(value) - 8; mc_man = (value >> (mc_exp + 3)) & 0x0F; return 0x80 | (mc_exp << 4) | mc_man; } /* V2 exponential field decoding */ /* Calculate Maximum Response Delay from Maximum Response Code * * RFC3810, relevant sections: * - 5.1.3. Maximum Response Code defines the decoding formula: * 0 1 2 3 4 5 6 7 8 9 A B C D E F * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * |1| exp | mant | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * Maximum Response Delay = (mant | 0x1000) << (exp+3) * - 9.3. Query Response Interval * * After decode, MRC represents the Maximum Response Delay (MRD) in * units of milliseconds. */ static inline unsigned long mldv2_mrd(const struct mld2_query *mlh2) { unsigned long mc_mrc = ntohs(mlh2->mld2q_mrc); if (mc_mrc < MLD_MRC_MIN_THRESHOLD) { return mc_mrc; } else { unsigned long mc_man, mc_exp; mc_exp = MLDV2_MRC_EXP(mc_mrc); mc_man = MLDV2_MRC_MAN(mc_mrc); return (mc_man | 0x1000) << (mc_exp + 3); } } /* Calculate Querier's Query Interval from Querier's Query Interval Code * * RFC3810, relevant sections: * - 5.1.9. QQIC (Querier's Query Interval Code) defines the decoding formula: * 0 1 2 3 4 5 6 7 * +-+-+-+-+-+-+-+-+ * |1| exp | mant | * +-+-+-+-+-+-+-+-+ * QQI = (mant | 0x10) << (exp + 3) * - 9.2. Query Interval * - 9.12. Older Version Querier Present Timeout * (the [Query Interval] in the last Query received) * * After decode, QQIC represents the Querier's Query Interval in units * of seconds. */ static inline unsigned long mldv2_qqi(const struct mld2_query *mlh2) { unsigned long qqic = mlh2->mld2q_qqic; if (qqic < MLD_QQIC_MIN_THRESHOLD) { return qqic; } else { unsigned long mc_man, mc_exp; mc_exp = MLDV2_QQIC_EXP(qqic); mc_man = MLDV2_QQIC_MAN(qqic); return (mc_man | 0x10) << (mc_exp + 3); } } #endif
