On Mon, Mar 30, 2026 at 07:16:09PM +0000, Ujjal Roy wrote: > In IGMP, QQIC and MRC fields are not currently encoded
s/currently/correctly/ ? > when generating query packets. Since the receiver of the > query interprets these fields using the IGMPv3 floating- > point decoding logic, any raw interval value that exceeds > the linear threshold is currently parsed incorrectly as > an exponential value, leading to an incorrect interval > calculation. > > Encode and assign the corresponding protocol fields during > query generation. Introduce the logic to dynamically > calculate the exponent and mantissa using bit-scan (fls). > This ensures QQIC and MRC fields (8-bit) are properly > encoded when transmitting query packets with intervals > that exceed their respective linear threshold value of > 128 (for QQI/MRT). > > RFC 3376: if QQIC/MRC >= 128, the QQIC/MRC field represents > a floating-point value as follows: > 0 1 2 3 4 5 6 7 > +-+-+-+-+-+-+-+-+ > |1| exp | mant | > +-+-+-+-+-+-+-+-+ > > Signed-off-by: Ujjal Roy <[email protected]> [...] > +static inline u8 igmpv3_exp_field_encode(unsigned long value) > +{ > + u8 mc_exp, mc_man; > + > + /* RFC3376: QQIC/MRC < 128 is literal */ > + if (value < IGMPV3_EXP_MIN_THRESHOLD) > + return (u8)value; return value; > + > + /* Saturate at max representable (mant = 0xF, exp = 7) -> 31744 */ > + if (value >= IGMPV3_EXP_MAX_THRESHOLD) > + return 0xFF; > + > + mc_exp = (u8)(fls(value) - 8); > + mc_man = (u8)((value >> (mc_exp + 3)) & 0x0F); Drop the casts? Same in other places throughout the patchset. > + > + return 0x80 | (mc_exp << 4) | mc_man; > +}
