/*

 * ip.c

 *

 * IP Level Specific functions

 *

 */



//Structure definitions

_IP_HEADER IP_HEADER;



//Have you ever heard about little endian and big endian machines and how they store data?

//Well, we have to deal with it here, inverting the IP values

static void swapIPHeader(_IP_HEADER*  header) {

   header->TotalLength = swap16(header->TotalLength);

   header->Identification = swap16(header->Identification);

   header->FragmentInfo = swap16(header->FragmentInfo);

   header->HeaderChecksum = swap16(header->HeaderChecksum);

}



//Process IP request reading from NIC and putting in correct vars

void processIP(void) {



   //Get 20 Bytes IP Header from nic, corrects it and put in IP_HEADER Structure

   getNicData(&IP_HEADER,20);

   swapIPHeader(&IP_HEADER);



   //Set other needed vars with sizes

   hdr_len = (IP_HEADER.VersionIHL & 0x0F) << 2;

   opt_len = hdr_len - 20;

   version = IP_HEADER.VersionIHL >> 4;



   #ifdef DEBUG

      printf("Src IP: %u.%u.%u.%u \n\r", IP_HEADER.SourceAddress.ip0, IP_HEADER.SourceAddress.ip1,

              IP_HEADER.SourceAddress.ip2, IP_HEADER.SourceAddress.ip3);

      printf("Prot: %x\n\r", IP_HEADER.Protocol);

      printf("Ident: %Lx\n\r", IP_HEADER.Identification);

   #endif      

}



//Send IP Header to the correct place in nic's buffer

void load_IP_header(long int IP_packet_length, int IP_send_protocol) {



   //Vars

   int i;

   long int prev_chksum;



   //Set IP on the Ethernet Field for Protocol Type

   outport(NIC_DATA, IP >> 8);   // IP packet

   outport(NIC_DATA, IP);



   //Go filling the IP Header fields

   chksum = 0;

   outportw(NIC_DATA, 0x4500);

   outportw(NIC_DATA, IP_packet_length);

   outportw(NIC_DATA, IP_HEADER.Identification);   //

   outportw(NIC_DATA, 0x0000);   // Okay to fragment

   outportw(NIC_DATA, 0x8000 + IP_send_protocol);   // Time-To-Live set a 255



   //Compute and send header checksum

   calc_chksum( make16(my_ip[0],my_ip[1]));

   calc_chksum( make16(my_ip[2],my_ip[3]));

   calc_chksum( make16(IP_HEADER.SourceAddress.ip0,IP_HEADER.SourceAddress.ip1));

   calc_chksum( make16(IP_HEADER.SourceAddress.ip2,IP_HEADER.SourceAddress.ip3));

   outportw(NIC_DATA, ~chksum);  // Header Checksum



   //And Write to the NIC the source IP (picnic ip) and destination IP (client)

   writeNicTxBuffer(my_ip,4);

   writeNicTxBuffer(&IP_HEADER.SourceAddress,4);

}