source: edk_user_repository/WARP/sw_services/WARPxilnet_v3_01_a/src/xilnet_ip.c

////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2004 Xilinx, Inc.  All rights reserved.
//
// Xilinx, Inc.
// XILINX IS PROVIDING THIS DESIGN, CODE, OR INFORMATION "AS IS" AS A
// COURTESY TO YOU.  BY PROVIDING THIS DESIGN, CODE, OR INFORMATION AS
// ONE POSSIBLE   IMPLEMENTATION OF THIS FEATURE, APPLICATION OR
// STANDARD, XILINX IS MAKING NO REPRESENTATION THAT THIS IMPLEMENTATION
// IS FREE FROM ANY CLAIMS OF INFRINGEMENT, AND YOU ARE RESPONSIBLE
// FOR OBTAINING ANY RIGHTS YOU MAY REQUIRE FOR YOUR IMPLEMENTATION.
// XILINX EXPRESSLY DISCLAIMS ANY WARRANTY WHATSOEVER WITH RESPECT TO
// THE ADEQUACY OF THE IMPLEMENTATION, INCLUDING BUT NOT LIMITED TO
// ANY WARRANTIES OR REPRESENTATIONS THAT THIS IMPLEMENTATION IS FREE
// FROM CLAIMS OF INFRINGEMENT, IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS FOR A PARTICULAR PURPOSE.
//
// File   : ip.c
// Date   : 2002, March 20.
// Author : Sathya Thammanur
// Company: Xilinx
// Group  : Emerging Software Technologies
//
// Summary:
// IP layer specific functions
//
// $Id: ip.c,v 1.2.8.6 2005/11/15 23:41:10 salindac Exp $
//
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
// see copyright.txt for Rice University/Mango Communications modifications
////////////////////////////////////////////////////////////////////////////////

#include <xilnet_xilsock.h>


/*
 * initialize xilnet ip address
 */
void xilnet_ip_init(unsigned char* addr) {
   int k = 0;
   int j;
   int sum = 0;

   for (j = 0; j < 3; j++) {

      // parse input for dotted decimal notation of ip address
      while(addr[k] != '.') {
         sum = sum * 10 + addr[k] - 48;
         k++;
      }

      k++; // move over the dot
      node_ip_addr[j] = (unsigned char) sum;
      sum = 0;
   }

   // read last byte of ip address
   while (addr[k] != '\0') {
      sum = sum * 10 + addr[k] - 48;
      k++;
   }
   node_ip_addr[3] = (unsigned char) sum;

}


/*
 * ip datagram handler:
 * checks for the source ip address and calls the corr protocol handler
 * no checksum calc is done to detect any errors
 */

int xilnet_ip(unsigned char*buf, int len) {

  int iplen = 0;
  struct xilnet_ip_hdr *iph = (struct xilnet_ip_hdr *) (buf+ETH_HDR_LEN);
#ifdef _DEBUG_
  //print("In ip(): \n");
#endif

  if ((buf+ETH_HDR_LEN)[IP_DADDR_BASE] == node_ip_addr[0] && (buf+ETH_HDR_LEN)[IP_DADDR_BASE+1] == node_ip_addr[1] &&
      (buf+ETH_HDR_LEN)[IP_DADDR_BASE+2] == node_ip_addr[2] && ((buf+ETH_HDR_LEN)[IP_DADDR_BASE+3] == node_ip_addr[3] || (buf+ETH_HDR_LEN)[IP_DADDR_BASE+3] == 255 )) {
    // update hw addr table
    xilnet_eth_update_hw_tbl(buf, ETH_PROTO_IP);

    iplen = (unsigned short)( ((((unsigned short)buf[ETH_HDR_LEN+2]) << 8) & 0xFF00) +
                                (((unsigned short)buf[ETH_HDR_LEN+3]) & 0x00FF) );


    // call corr protocol handler with the ip datagram
    switch (iph->prot) {
      case IP_PROTO_UDP:
    return (xilnet_udp(buf+ETH_HDR_LEN, iplen));
    break;
      case IP_PROTO_TCP:
    return (xilnet_tcp(buf+ETH_HDR_LEN, iplen));
    break;
      case IP_PROTO_ICMP:
    return (xilnet_icmp(buf+ETH_HDR_LEN, iplen));
    break;
      default:
    break;
      }
  }

  return 0;
}


/*
 * xilnet_ip_header: fills in the ip header for proto
 */
int ip_id_cnt = 0;

void xilnet_ip_header(unsigned char* buf, int len, int proto, unsigned char *peer_ip_addr) {

   struct xilnet_ip_hdr *iph = (struct xilnet_ip_hdr*) buf;


#ifdef _DEBUG_
   //  print("ip_header(): \n");
#endif /*  _DEBUG_ */

   buf[0] = IP_VERSION << 4;
   buf[0] |= IP_HDR_LEN;
   iph->tos = IP_TOS;
   iph->total_len = Xil_Htons(len);
   iph->ident = Xil_Htons(ip_id_cnt++);
   iph->frag_off = Xil_Htons(IP_FRAG_OFF);
   iph->ttl = IP_TTL;
   iph->prot = proto;
   iph->check_sum = 0;
   buf[IP_SADDR_BASE]  = node_ip_addr[0];
   buf[IP_SADDR_BASE+1] = node_ip_addr[1];
   buf[IP_SADDR_BASE+2] = node_ip_addr[2];
   buf[IP_SADDR_BASE+3] = node_ip_addr[3];
   buf[IP_DADDR_BASE]  = peer_ip_addr[0];
   buf[IP_DADDR_BASE+1] = peer_ip_addr[1];
   buf[IP_DADDR_BASE+2] = peer_ip_addr[2];
   buf[IP_DADDR_BASE+3] = peer_ip_addr[3];
   iph->check_sum = Xil_Htons(xilnet_ip_calc_chksum(buf, IP_HDR_LEN*4));

}


/*
 * xilnet_ip_calc_chksum: compute checksum for ip header
 */

unsigned short xilnet_ip_calc_chksum(unsigned char* buf, int len) {

   unsigned int sum = 0;
   unsigned short w16 = 0;
   int i;

   for (i = 0; i < len; i = i + 2) {
      w16 = ((buf[i] << 8) & 0xFF00) + (buf[i+1] & 0x00FF);
      sum = sum + (unsigned int) w16;
   }

   while (sum >> 16)
      sum = (sum & 0xFFFF) + (sum >> 16);

   return (unsigned short) (~sum);
}