File content as of revision 10:f0854784e960:

#include "mbed.h"
#include   "io.h"
#include  "log.h"
#include  "net.h"
#include  "arp.h"
#include  "ip4.h"
#include  "ip6.h"
#include  "phy.h"
#include  "eth.h"

#define HEADER_SIZE 14
__packed struct header
{
    char     dst[6];
    char     src[6];
    uint16_t typ;
};

char EthLocalMac[6];

static void typeToString(uint16_t type, int size, char* text)
{
    switch (type)
    {
        case ARP:  strncpy (text, "ARP" , size);        break;
        case IPV4: strncpy (text, "IPV4", size);        break;
        case IPV6: strncpy (text, "IPV6", size);        break;
        default:   snprintf(text, size, "%04hX", type); break;
    }
}
static bool getIsSolicited(char* p)
{
    if (*p++ != 0x33) return false;
    if (*p++ != 0x33) return false;
    if (*p++ != 0xff) return false;
    return true;
}
static bool getIsSame(char* pA, char* pB)
{
    return memcmp(pA, pB, 6) == 0;
}
static bool getIsSameGroup(char* pA, char* pB)
{
    pA += 3;
    pB += 3;
    if (*pA++ != *pB++) return false;
    if (*pA++ != *pB++) return false;
    return *pA == *pB;
}

static void finalisePacket(int action, int type, int dataLength, void* pPacket, int* pSize)
{
    struct header * pHeader = (header*)pPacket;

    switch (action)
    {
        case DO_NOTHING:
            return;
        case UNICAST:
        case UNICAST_DNS:
        case UNICAST_DHCP:
            break;
        case MULTICAST_NODE:
            pHeader->dst[0] = type == IPV6 ? 0x33 : 0x01;
            pHeader->dst[1] = type == IPV6 ? 0x33 : 0x00;
            pHeader->dst[2] = type == IPV6 ? 0x00 : 0x5e;
            pHeader->dst[3] = 0x00;
            pHeader->dst[4] = 0x00;
            pHeader->dst[5] = 0x01;
            break;
        case MULTICAST_ROUTER:
            pHeader->dst[0] = type == IPV6 ? 0x33 : 0x01;
            pHeader->dst[1] = type == IPV6 ? 0x33 : 0x00;
            pHeader->dst[2] = type == IPV6 ? 0x00 : 0x5e;
            pHeader->dst[3] = 0x00;
            pHeader->dst[4] = 0x00;
            pHeader->dst[5] = 0x02;
            break;
        case MULTICAST_MDNS:
            pHeader->dst[0] = type == IPV6 ? 0x33 : 0x01;
            pHeader->dst[1] = type == IPV6 ? 0x33 : 0x00;
            pHeader->dst[2] = type == IPV6 ? 0x00 : 0x5e;
            pHeader->dst[3] = 0x00;
            pHeader->dst[4] = 0x00;
            pHeader->dst[5] = 0xfb;
            break;
        case MULTICAST_LLMNR:
            pHeader->dst[0] = type == IPV6 ? 0x33 : 0x01;
            pHeader->dst[1] = type == IPV6 ? 0x33 : 0x00;
            pHeader->dst[2] = type == IPV6 ? 0x00 : 0x5e;
            pHeader->dst[3] = type == IPV6 ? 0x01 : 0x00;
            pHeader->dst[4] = type == IPV6 ? 0x00 : 0x00;
            pHeader->dst[5] = type == IPV6 ? 0x03 : 0xfc;
            break;
        case BROADCAST:
            memset(pHeader->dst, 0xFF, 6); //Set to broadcast
            break;
        default:
            LogTimeF("Unknown ETH action %d\r\n", action);
            return;
    }
    memcpy(pHeader->src,  EthLocalMac, 6);        //Put our MAC into the source
    pHeader->typ = NetToHost16(type);
    
    *pSize = HEADER_SIZE + dataLength;
}
int EthHandlePacket(void* pPacket, int* pSize)
{
    struct header * pHeader = (header*)pPacket;
    int dataLength = *pSize - HEADER_SIZE;
    void* pData = (char*)pPacket + HEADER_SIZE;
    
    bool isSpanningTree = pHeader->dst[0] == 0x01 && pHeader->dst[1] == 0x80 && pHeader->dst[2] == 0xC2;
    
    bool isMe           = getIsSame(pHeader->dst, EthLocalMac);
    bool isMulticast    = pHeader->dst[0] & 0x01;
    bool isSolicited    = getIsSolicited(pHeader->dst);
    bool isGroup        = isSolicited && getIsSameGroup(pHeader->dst, EthLocalMac);
    
    bool doIt = isMe || (isMulticast && !isSolicited) || isGroup;
    
    if (!doIt) return DO_NOTHING;

    if (isSpanningTree) return DO_NOTHING; //Drop - these multicast messages come from Sonos devices to prevent issues between wireless and wired.
    
    uint16_t type = NetToHost16(pHeader->typ);
    if (type < 1500) return DO_NOTHING; //drop 802.3 messages

    int   action = DO_NOTHING;
    switch (type)
    {
        case ARP:  action = ArpHandleReceivedPacket(pHeader->src, pData, &dataLength, pHeader->dst); break;
        case IPV4: action = Ip4HandleReceivedPacket(pHeader->src, pData, &dataLength, pHeader->dst); break;
        case IPV6: action = Ip6HandleReceivedPacket(pHeader->src, pData, &dataLength, pHeader->dst); break;
        default:
            char text[20];
            LogTimeF("\r\nEthernet packet not handled\r\n");
            NetMacToString(pHeader->dst, sizeof(text), text);
            LogTimeF("Destination:  %s\r\n", text);
            NetMacToString(pHeader->src, sizeof(text), text);
            LogTimeF("Source:       %s\r\n", text);
            typeToString(type, sizeof(text), text);
            LogTimeF("EtherType:    %s\r\n", text);        
            break;
    }
    
    finalisePacket(action, type, dataLength, pPacket, pSize);
    
    return action;
}
int EthPollForPacketToSend(void* pPacket, int* pSize)
{
    struct header * pHeader = (header*)pPacket;
    void* pData = (char*)pPacket + HEADER_SIZE;
    
    int dataLength = 0;
    int type = 0;
    int action = DO_NOTHING;

    if (action == DO_NOTHING)
    {
        action = Ip6PollForPacketToSend(pData, &dataLength, pHeader->dst);
        type = IPV6;
    }
    
    if (action == DO_NOTHING)
    {
        action = Ip4PollForPacketToSend(pData, &dataLength, pHeader->dst);
        type = IPV4;
    }
    
    finalisePacket(action, type, dataLength, pPacket, pSize);
    
    return action;
}