//
// Created by epagris on 2022.12.08..
//

#include "arp_packet.h"
#include "ethernet_frame.h"
#include "../../utils.h"
#include "../../eth_interface.h"

static EthernetAddress emptyEthAddr = { 0x00 };

static void arp_fetch_mapping(const ArpProps * arpProps, ArpCache * arpc) {
    ArpEntry entry;
    if ((memcmp(arpProps->SHA, emptyEthAddr, ETH_HW_ADDR_LEN) != 0) && (arpProps->SPA != 0)) {
        memcpy(entry.eth, arpProps->SHA, ETH_HW_ADDR_LEN);
        entry.ip = arpProps->SPA;
        arpc_learn(arpc, &entry);
    }
    if ((memcmp(arpProps->THA, emptyEthAddr, ETH_HW_ADDR_LEN) != 0) && (arpProps->TPA != 0)) {
        memcpy(entry.eth, arpProps->THA, ETH_HW_ADDR_LEN);
        entry.ip = arpProps->TPA;
        arpc_learn(arpc, &entry);
    }
}

int parse_arp(const uint8_t *hdr, uint32_t size, PcktHeaderElement *pcktHdrLe, struct EthInterface_ *intf, PcktProcFnPassbackData *pb) {
    // parse ARP packet
    ArpProps *arpProps = HEADER_FETCH_PROPS(ArpProps, pcktHdrLe);
    FETCH_WORD_H2N_ADVANCE(&arpProps->HTYPE, hdr); // hardware type
    FETCH_WORD_H2N_ADVANCE(&arpProps->PTYPE, hdr); // protocol type
    FETCH_BYTE_ADVANCE(&arpProps->HLEN, hdr); // hardware address size
    FETCH_BYTE_ADVANCE(&arpProps->PLEN, hdr); // protocol address size
    FETCH_WORD_H2N_ADVANCE(&arpProps->OPER, hdr); // operation code
    FETCH_ADVANCE(&arpProps->SHA, hdr, ETH_HW_ADDR_LEN); // sender HW address
    FETCH_ADVANCE(&arpProps->SPA, hdr, sizeof(ip4_addr)); // sender protocol address
    FETCH_ADVANCE(&arpProps->THA, hdr, ETH_HW_ADDR_LEN); // target HW address
    FETCH_ADVANCE(&arpProps->TPA, hdr, sizeof(ip4_addr)); // target protocol address

    // fill-in common packet header fields
    arpProps->validityOK = true; // TODO!
    arpProps->containedPacketClass = 0;
    arpProps->headerSize = ETH_ARP_HEADER_SIZE;

    // learn new mapping
    arp_fetch_mapping(arpProps, intf->arpc);

    return arpProps->validityOK ? PROC_FN_RET_OK : PROC_FN_RET_ABORT;
}

void insert_arp_header(uint8_t *hdr, const PcktHeaderElement *headers, EthInterface *intf) {
    ArpProps *arpProps = HEADER_FETCH_PROPS(ArpProps, headers);

    FILL_WORD_H2N_ADVANCE(hdr, arpProps->HTYPE); // hardware type
    FILL_WORD_H2N_ADVANCE(hdr, arpProps->PTYPE); // protocol type
    FILL_BYTE_ADVANCE(hdr, &arpProps->HLEN); // hardware address size
    FILL_BYTE_ADVANCE(hdr, &arpProps->PLEN); // protocol address size
    FILL_WORD_H2N_ADVANCE(hdr, arpProps->OPER); // operation code
    FILL_ADVANCE(hdr, &arpProps->SHA, ETH_HW_ADDR_LEN); // sender HW address
    FILL_ADVANCE(hdr, &arpProps->SPA, sizeof(ip4_addr)); // sender protocol address
    FILL_ADVANCE(hdr, &arpProps->THA, ETH_HW_ADDR_LEN); // target HW address
    FILL_ADVANCE(hdr, &arpProps->TPA, sizeof(ip4_addr)); // target protocol address
}