File content as of revision 43:bc028d5a6424:

#include   "mbed.h"
#include    "log.h"
#include "action.h"
#include    "net.h"
#include    "eth.h"
#include    "mac.h"
#include   "dhcp.h"
#include     "ar.h"
#include     "nr.h"
#include     "io.h"
#include    "ip4.h"

#define REQUEST   1
#define REPLY     2

bool ArpTrace = false;

uint32_t ArpAddressToResolve;
bool     ArpResolveRequestFlag = false;

__packed struct header
{
    int16_t  hardwareType;             //16.bit: (ar$hrd) Hardware address space (e.g., Ethernet, Packet Radio Net). Always 1.
    int16_t  protocolType;             //16.bit: (ar$pro) Protocol address space.  For Ethernet hardware, this is from the set of type fields ether_typ$<protocol>. As held in eth.h, eg IPv4 = 0x8000.
    int8_t   hardwareLength;           // 8.bit: (ar$hln) byte length of each hardware address. Always 6 bytes.
    int8_t   protocolLength;           // 8.bit: (ar$pln) byte length of each protocol address. Always 4 bytes.
    int16_t  opCode;                   //16.bit: (ar$op)  opcode (ares_op$REQUEST = 1 | ares_op$REPLY = 2), high byte transmitted first.
    char     senderHardwareAddress[6]; //nbytes: (ar$sha) Hardware address of sender of this packet, n from the ar$hln field.
    uint32_t senderProtocolAddress;    //mbytes: (ar$spa) Protocol address of sender of this packet, m from the ar$pln field.
    char     targetHardwareAddress[6]; //nbytes: (ar$tha) Hardware address of target of this packet (if known).
    uint32_t targetProtocolAddress;    //mbytes: (ar$tpa) Protocol address of target.
};

static void logHeader(void * pPacket)
{
    struct header*         pHeader = (header*)pPacket;
    char text[30];
    
    if (NetTraceVerbose)
    {
        LogTime("ARP header\r\n");
        if (NetToHost16(pHeader->hardwareType) == ETHERNET) Log ("  hardwareType          = ETHERNET\r\n");
        else                                                LogF("  hardwareType          = %d\r\n", NetToHost16(pHeader->hardwareType));
        EthProtocolToString(NetToHost16(pHeader->protocolType), sizeof(text), text);
        LogF("  protocolType          = %s\r\n", text);
        LogF("  hardwareLength        = %d\r\n",             pHeader->hardwareLength);
        LogF("  protocolLength        = %d\r\n",             pHeader->protocolLength);
        if      (NetToHost16(pHeader->opCode) == REQUEST) Log ("  opCode                = REQUEST\r\n");
        else if (NetToHost16(pHeader->opCode) == REPLY  ) Log ("  opCode                = REPLY\r\n");
        else                                              LogF("  opCode                = %d\r\n", NetToHost16(pHeader->opCode));
        MacToString(pHeader->senderHardwareAddress, sizeof(text), text);
        LogF("  senderHardwareAddress = %s\r\n", text);
        Ip4AddressToString(pHeader->senderProtocolAddress, sizeof(text), text);
        LogF("  senderProtocolAddress = %s\r\n", text);
        MacToString(pHeader->targetHardwareAddress, sizeof(text), text);
        LogF("  targetHardwareAddress = %s\r\n", text);
        Ip4AddressToString(pHeader->targetProtocolAddress, sizeof(text), text);
        LogF("  targetProtocolAddress = %s\r\n", text);
    }
    else
    {
        Log("ARP header ");
        MacToString       (pHeader->senderHardwareAddress, sizeof(text), text);           Log(text);
        Ip4AddressToString(pHeader->senderProtocolAddress, sizeof(text), text); Log("["); LogF(text); Log("] >>> ");
        MacToString       (pHeader->targetHardwareAddress, sizeof(text), text);           LogF(text);
        Ip4AddressToString(pHeader->targetProtocolAddress, sizeof(text), text); Log("["); LogF(text); Log("]\r\n");
        
    }
}

int ArpHandleReceivedPacket(void (*traceback)(void), char* pSrcMac, void * pPacket, int* pSize, char* pDstMac)
{
    struct header*         pHeader = (header*)pPacket;
    int16_t           hardwareType = NetToHost16(pHeader->hardwareType);
    int16_t           protocolType = NetToHost16(pHeader->protocolType);
    int8_t          hardwareLength =             pHeader->hardwareLength;
    int8_t          protocolLength =             pHeader->protocolLength;
    int16_t                 opCode = NetToHost16(pHeader->opCode);
    uint32_t targetProtocolAddress =             pHeader->targetProtocolAddress;
    
    if (hardwareType          != ETHERNET     ) return DO_NOTHING; //This is not ethernet
    if (protocolType          != IPV4         ) return DO_NOTHING; //This is not IPv4
    if (hardwareLength        != 6            ) return DO_NOTHING; //This is not a MAC hardware address
    if (protocolLength        != 4            ) return DO_NOTHING; //This is not an IPv4 IP address
    if (targetProtocolAddress != DhcpLocalIp  ) return DO_NOTHING; //This packet was not addressed to us
    
    switch (opCode)
    {
        case REQUEST:
            if (ArpTrace)
            {
                if (NetTraceNewLine) Log("\r\n");
                LogTime("ARP received request\r\n");
                logHeader(pPacket);
                if (NetTraceStack) traceback();
            }   
            MacCopy(pHeader->targetHardwareAddress,  pHeader->senderHardwareAddress);
                    pHeader->targetProtocolAddress = pHeader->senderProtocolAddress;
            MacCopy(pHeader->senderHardwareAddress,  MacLocal);
                    pHeader->senderProtocolAddress = DhcpLocalIp;
                    pHeader->opCode                = NetToHost16(REPLY);
            MacCopy(pDstMac, pSrcMac);
            if (ArpTrace) logHeader(pPacket);
            return ActionMakeFromDestAndTrace(UNICAST, ArpTrace && NetTraceStack);
            
        case REPLY:
            if (ArpTrace)
            {
                if (NetTraceNewLine) Log("\r\n");
                LogTime("ARP received reply\r\n");
                logHeader(pPacket);
                if (NetTraceStack) traceback();
            }   
            ArAddIp4Record(pHeader->senderHardwareAddress, pHeader->senderProtocolAddress);
            NrMakeRequestForNameFromIp4(pHeader->senderProtocolAddress);
            return DO_NOTHING;
            
        default:
            return DO_NOTHING;
    }
}
int ArpPollForPacketToSend(void* pPacket, int* pSize)
{
    if (!ArpResolveRequestFlag) return DO_NOTHING;
    ArpResolveRequestFlag = false;
        
    struct header* pHeader = (header*)pPacket;
    
    pHeader->hardwareType   = NetToHost16(ETHERNET);
    pHeader->protocolType   = NetToHost16(IPV4);
    pHeader->hardwareLength = 6;
    pHeader->protocolLength = 4;
    pHeader->opCode         = NetToHost16(REQUEST);
    
    MacClear(pHeader->targetHardwareAddress);
             pHeader->targetProtocolAddress = ArpAddressToResolve;
    MacCopy (pHeader->senderHardwareAddress,  MacLocal);
             pHeader->senderProtocolAddress = DhcpLocalIp;
           
    *pSize = sizeof(header);
    
    if (ArpTrace)
    {
        if (NetTraceNewLine) Log("\r\n");
        LogTime("ARP send request\r\n");
        logHeader(pPacket);
    }
    return ActionMakeFromDestAndTrace(BROADCAST, ArpTrace && NetTraceStack);
}