#include "icmp_connblock.h"

#include <stddef.h>

#include "../packet_parsers/packet_parsers.h"
#include "../../utils.h"
#include "../../dynmem.h"
#include "../../pckt_assembler.h"
#include "../../eth_interface.h"
#include "../packet_parsers/icmp_packet.h"
#include "ipv4_connblock.h"

static bool filtIcmp(const PcktSieveFilterCondition * filtCond, const PcktProps * contProps, const PcktProps * ownProps, EthInterface * intf) {
    IPv4Props * ipProps = (IPv4Props *) contProps;
    IcmpProps * icmpProps = (IcmpProps *) ownProps;

    return ipProps->Protocol == ETH_ICMP_PACKET_CLASS;
}

static int icmp_recv_cb(const Pckt * pckt, PcktSieveLayerTag tag) {
    IcmpProps * icmpProps = HEADER_FETCH_PROPS(IcmpProps, pckt->header);
    EthInterface * intf = (EthInterface *) tag.p; // icmp_new_connblock() puts pointer to intf into tag field

    switch (icmpProps->type) {
        case ICMP_MT_ECHO_REQUEST: {
            icmpProps->type = ICMP_MT_ECHO_REPLY; // replace request with reply
            icmpProps->hdrInsFn = insert_icmp_header;

            // swap source an destination IP addresses
            IPv4Props * iPv4Props = HEADER_FETCH_PROPS(IPv4Props, pckt->header->prev);
            ip4_addr tmpIp = iPv4Props->SourceIPAddr;
            iPv4Props->SourceIPAddr = iPv4Props->DestIPAddr;
            iPv4Props->DestIPAddr = tmpIp;
            iPv4Props->hdrInsFn = insert_ipv4_header;

            // swap Ethernet fields
            EthernetAddress tmpEth;
            EthernetProps * ethProps = HEADER_FETCH_PROPS(EthernetProps, pckt->header->prev->prev);
            HWACPY(tmpEth, ethProps->sourceAddr);
            HWACPY(ethProps->sourceAddr, ethProps->destAddr);
            HWACPY(ethProps->destAddr, tmpEth);
            ethProps->hdrInsFn = insert_ethernet_header;

            // payload is the same...

            // assemble packet
            RawPckt raw;
            pckt_assemble(&raw, pckt);

            // release headers
            pckthdr_chain_free(pckt->header);

            ethinf_transmit(intf, &raw);
        }
            break;
        default:
            break;
    }

    return 0;
}

ConnBlock icmp_new_connblock(EthInterface * intf) {
    ConnBlock icmpConnB;
    ConnBlock ipConnB = ipv4_new_connblock(intf, IPv4_IF_ADDR, NULL); // create new IPv4 connection block

    PcktSieveFilterCondition filtCond;
    packfiltcond_zero(&filtCond);
    PcktSieveLayerTag tag;
    tag.p = intf; // Ethernet-interface passed in 'tag.p'
    icmpConnB.sieveLayer = packsieve_new_layer(ipConnB.sieveLayer, &filtCond, false, filtIcmp, icmp_recv_cb, tag, ETH_ICMP_PACKET_CLASS);
    ASSERT_NULL(icmpConnB.sieveLayer);

    icmpConnB.intf = intf;

    SNPRINTF(icmpConnB.sieveLayer->infoTag, PCKT_SIEVE_INFOTAG_LEN, "ICMP (ping)");

    return icmpConnB;
}