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

#include "icmp_packet.h"
#include "../../utils.h"
#include "ipv4_packet.h"

int parse_icmp(const uint8_t *hdr, uint32_t size, PcktHeaderElement *pcktHdrLe, struct EthInterface_ *intf) {
    // parse header
    IcmpProps *icmpProps = HEADER_FETCH_PROPS(IcmpProps, pcktHdrLe);
    FETCH_BYTE_ADVANCE(&icmpProps->type, hdr);
    FETCH_BYTE_ADVANCE(&icmpProps->code, hdr);
    FETCH_WORD_ADVANCE(&icmpProps->checksum, hdr);
    FETCH_WORD_ADVANCE(&icmpProps->identifier, hdr);
    FETCH_WORD_ADVANCE(&icmpProps->sequenceNumber, hdr);

    // fill-in common fields
    icmpProps->validityOK = true; // TODO...
    icmpProps->containedPacketClass = 0;
    icmpProps->headerSize = ETH_ICMP_HEADER_SIZE;

    return 0;
}

void insert_icmp_header(uint8_t *hdr, const PcktHeaderElement *headers) {
    uint8_t * hdrStart = hdr;
    IcmpProps *icmpProps = HEADER_FETCH_PROPS(IcmpProps, headers);
    FILL_BYTE_ADVANCE(hdr, &icmpProps->type);
    FILL_BYTE_ADVANCE(hdr, &icmpProps->code);
    uint8_t * ChkSumPtr = hdr;
    icmpProps->checksum = 0;
    FILL_ADVANCE(hdr, &icmpProps->checksum, 2);
    FILL_ADVANCE(hdr, &icmpProps->identifier, 2);
    FILL_ADVANCE(hdr, &icmpProps->sequenceNumber, 2);

    IPv4Props * ipProps = HEADER_FETCH_PROPS(IPv4Props, headers->prev);
    icmpProps->checksum = chksum(hdrStart, ipProps->TotalLength - ETH_IPv4_HEADER_SIZE);
    FILL_WORD_H2N_ADVANCE(ChkSumPtr, icmpProps->checksum);
}