arp.c

Pic Nic 16f877/18f452控制 rtl8019as 原代码

/*
 * arp.c
 *
 * Address Resolution Protocol (ARP) specific functions
 *
 */

//The arp packet structure
_ARP_PACKET ARP_PACKET;

//Load Ethernet Frame Header to the NIC
void load_ethernet_header(void) {

   //Put nic in the beggining of tx buffer area
   remote_dma_setup(WRITE,XMT_BUF_START);

   //Write source and dst mac to the nic
   writeNicTxBuffer(ETHERNET_HEADER.mac_source,6);
   writeNicTxBuffer(physical_address,6);
}

//Swap ARP Packet Bytes
static void swapARP(_ARP_PACKET*  header) {
   header->HardwareType = swap16(header->HardwareType);
   header->Protocol = swap16(header->Protocol);
   header->Operation = swap32(header->Operation);
}

//Sends an ARP answer telling the client what mac address our IP have
void arpResponse(void) {
   int i;

   //Prepares and ARP Response Packet
   load_ethernet_header();

   //Send Protocol Specific definitions
   outportw(NIC_DATA, ARP );
   outportw(NIC_DATA, 0x0001 );
   outportw(NIC_DATA, 0x0800 );
   outportw(NIC_DATA, 0x0604 );
   outportw(NIC_DATA, 0x0002 );

   //Source and Destination MAC and IP Addresses
   writeNicTxBuffer(physical_address,6);
   writeNicTxBuffer(my_ip,4);
   writeNicTxBuffer(ETHERNET_HEADER.mac_source,6);
   writeNicTxBuffer(&ARP_PACKET.SenderIPAddr,4);

   //Pad to 46 bytes (46-28=18) cause we have a minimum size to send
   for (i=0 ; i<18 ;i++)
      outport(NIC_DATA, 0x00);

   //Packet assmebled so let's send it
   sendPacket(60);
}

//Get an ARP request, check some conditions and send the ARP answer
//Computer asks "WHO HAS ARP X"
//We answer with our MAC if it's searching for us
void procesa_arp(void) {

   //Get ARP Packet Data and adjust it
   getNicData(&ARP_PACKET,24);
   swapARP(&ARP_PACKET);

   //Is the ARP Packet asking for picnic's ip address MAC?
   //If not just abort
   if (my_ip[0] != ARP_PACKET.TargetIPAddr.ip0
    || my_ip[1] != ARP_PACKET.TargetIPAddr.ip1
    || my_ip[2] != ARP_PACKET.TargetIPAddr.ip2
    || my_ip[3] != ARP_PACKET.TargetIPAddr.ip3) {
      fin_rx();
      break;
   }

   #ifdef DEBUG
      printf("IP: %u.%u.%u.%u \n\r",ARP_PACKET.SenderIPAddr.ip0, ARP_PACKET.SenderIPAddr.ip1,
            ARP_PACKET.SenderIPAddr.ip2, ARP_PACKET.SenderIPAddr.ip3);
      printf("Dst IP: %u.%u.%u.%u \n\r",ARP_PACKET.TargetIPAddr.ip0, ARP_PACKET.TargetIPAddr.ip1,
            ARP_PACKET.TargetIPAddr.ip2, ARP_PACKET.TargetIPAddr.ip3);
      printf("Type: %Lx\n\r", ARP_PACKET.Operation);
   #endif

   //If we arrived here, we shall answer politely
   fin_rx();
   arpResponse();
}