//
// Created by epagris on 2022.12.25..
//

#include "igmp_packet.h"
#include "../../utils.h"

//static uint16_t igmp_chksum(const uint8_t * hdr) {
//    // sum fields
//    uint32_t sum = 0;
//    const uint16_t *pField = (const uint16_t *) hdr;
//    for (uint8_t i = 0; i < (ETH_IGMP_HEADER_SIZE / sizeof(uint16_t)); i++) {
//        uint16_t field = pField[i];
//        if (i != 1) { // 6. 16-bit long field is the checksum itself, do not count in
//            sum += field;
//        }
//    }
//
//    while (sum >> 16) {
//        sum = (sum & 0xFFFF) + (sum >> 16);
//    }
//
//    // invert result
//    uint16_t sum16 = sum ^ 0xFFFF;
//    return sum16;
//}

void insert_igmp_header(uint8_t *hdr, const PcktHeaderElement *headers) {
    IgmpProps *igmpProps = HEADER_FETCH_PROPS(IgmpProps, headers);
    uint8_t * hdrBeg = hdr;

    FILL_ADVANCE(hdr, &igmpProps->type, 1);
    FILL_ADVANCE(hdr, &igmpProps->maxRespTime, 1);
    uint8_t * ChkSumPtr = hdr;
    igmpProps->checksum = 0;
    FILL_WORD_ADVANCE(hdr, igmpProps->checksum);
    FILL_DWORD_ADVANCE(hdr, igmpProps->groupAddr);

    igmpProps->checksum = chksum(hdrBeg, ETH_IGMP_HEADER_SIZE);
    memcpy(ChkSumPtr, &igmpProps->checksum, 2);
}

int parse_igmp(const uint8_t * hdr, uint32_t size, PcktHeaderElement * pcktHdrLe, struct EthInterface_ * intf) {
    // parse header
    IgmpProps *igmpProps = HEADER_FETCH_PROPS(IgmpProps, pcktHdrLe);
    FETCH_BYTE_ADVANCE(&igmpProps->type, hdr);
    FETCH_BYTE_ADVANCE(&igmpProps->maxRespTime, hdr);
    FETCH_WORD_ADVANCE(&igmpProps->checksum, hdr);
    FETCH_WORD_ADVANCE(&igmpProps->groupAddr, hdr);

    // fill-in common fields
    uint16_t calcChkSum = chksum(hdr, ETH_IGMP_HEADER_SIZE);
    igmpProps->validityOK = (calcChkSum == 0);
    igmpProps->containedPacketClass = 0;
    igmpProps->headerSize = ETH_IGMP_HEADER_SIZE;

    return 0;
}