ip.c

Pic Nic 16f877/18f452控制 rtl8019as 原代码

/*
 * 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);
}