/home/jander/temp/etherdune/ARP.cpp

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// EtherDune ARP Service
// Author: Javier Peletier <jm@friendev.com>
// Summary: Implements the ARP protocol as an EtherDune service
//
// Copyright (c) 2015 All Rights Reserved, http://friendev.com
//
// This source is subject to the GPLv2 license.
// Please see the License.txt file for more information.
// All other rights reserved.
//
// THIS CODE AND INFORMATION ARE PROVIDED "AS IS" WITHOUT WARRANTY OF ANY 
// KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
// PARTICULAR PURPOSE.

#include "ARP.h"

#define AC_LOGLEVEL 2
#include <ACLog.h>
ACROSS_MODULE("ARP");

static uint16_t minuteTimer = 60 * 1000 / NETWORK_TIMER_RESOLUTION;

ARPEntry ARPService::arpTable[ARP_TABLE_LENGTH];



ARPService::ARPService()
{
    memset(arpTable, -2, ARP_TABLE_LENGTH * sizeof(ARPEntry));
}

bool ARPService::onPacketReceived()
{
    
    if (packet.eth.etherType != ETHTYPE_ARP)
        return false;

    ACTRACE("processHeader");

    switch (packet.arp.OPER.l)
    {
        case ARP_OPCODE_REPLY_L:
        {

            ACTRACE("ARP Reply=%02x:%02x:%02x:%02x:%02x:%02x", packet.arp.senderMAC.b[0], packet.arp.senderMAC.b[1], packet.arp.senderMAC.b[2], packet.arp.senderMAC.b[3], packet.arp.senderMAC.b[4], packet.arp.senderMAC.b[5]);
            processARPReply();

            return true;
        }break;

        case ARP_OPCODE_REQ_L:
        {
            ACTRACE("ARP Request from=%02x:%02x:%02x:%02x:%02x:%02x", packet.arp.senderMAC.b[0], packet.arp.senderMAC.b[1], packet.arp.senderMAC.b[2], packet.arp.senderMAC.b[3], packet.arp.senderMAC.b[4], packet.arp.senderMAC.b[5]);

            if (packet.arp.targetIP.u == localIP.u)
                makeARPReply();
            return true;
        }break;

        default:
        {
            return true;
        }break;
    }
}


void ARPService::tick()
{
    minuteTimer--;

    if (minuteTimer == 0)
    {
        minuteTimer = 60 * 1000 / NETWORK_TIMER_RESOLUTION;

        for (ARPEntry* entry = arpTable + (ARP_TABLE_LENGTH - 1); entry >= arpTable; entry--)
        {
            if (entry->status_TTL > 0)
                entry->status_TTL--;
        }
    }
}


MACAddress* ARPService::whoHas(IPAddress& ip)
{
    for (ARPEntry* entry = arpTable + (ARP_TABLE_LENGTH - 1); entry >= arpTable; entry--)
    {
        if (ip.u == entry->ip.u && entry->status_TTL > 0)
        {
            entry->status_TTL = MAX_ARP_TTL;
            return &entry->mac;
        }
    }

    makeWhoHasARPRequest(ip);

    return NULL;


}



void ARPService::makeWhoHasARPRequest(IPAddress& ip)
{
    memset(&packet.eth.dstMAC, 0xFF, sizeof(MACAddress));
    packet.eth.srcMAC = packet.arp.senderMAC = localMAC;
    packet.eth.etherType=ETHTYPE_ARP;
    packet.arp.HTYPE = 0x0001;
    packet.arp.PTYPE = 0x0800;
    packet.arp.HLEN = 0x06;
    packet.arp.PLEN = 0x04;
    packet.arp.OPER = 0x0001;
    memset(&packet.arp.targetMAC, 0x00, sizeof(MACAddress));
    packet.arp.targetIP = ip;
    packet.arp.senderIP = localIP;



    packetSend(sizeof(EthernetHeader) + sizeof(ARPPacket), packet.raw);

}

void ARPService::makeARPReply()
{
    packet.arp.targetMAC = packet.eth.dstMAC = packet.eth.srcMAC;
    packet.arp.senderMAC = packet.eth.srcMAC = localMAC;
    packet.arp.OPER.l = ARP_OPCODE_REPLY_L;
    packet.arp.targetIP = packet.arp.senderIP;
    packet.arp.senderIP = localIP;

    packetSend(sizeof(EthernetHeader) + sizeof(ARPPacket), packet.raw);
}

void ARPService::processARPReply()
{
    int16_t lowest = MAX_ARP_TTL;
    ARPEntry * selectedEntry = NULL;
    for (ARPEntry* entry = arpTable + (ARP_TABLE_LENGTH - 1); entry >= arpTable; entry--)
    {
        if (entry->ip.u == packet.arp.senderIP.u)
        {
            selectedEntry = entry;
            break;
        }

        if (entry->status_TTL <= lowest)
        {
            lowest = entry->status_TTL;
            selectedEntry = entry;
        }
    }

    ACBREAK(selectedEntry!=NULL,"selectedEntry is NULL");

    selectedEntry->status_TTL = MAX_ARP_TTL;
    selectedEntry->ip = packet.arp.senderIP;
    selectedEntry->mac = packet.arp.senderMAC;

}