www.pudn.com > lwip-1.3.0.rar > ip_addr.c

/** 
 * @file 
 * This is the IPv4 address tools implementation. 
 * 
 */ 
 
/* 
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science. 
 * All rights reserved.  
 *  
 * Redistribution and use in source and binary forms, with or without modification,  
 * are permitted provided that the following conditions are met: 
 * 
 * 1. Redistributions of source code must retain the above copyright notice, 
 *    this list of conditions and the following disclaimer. 
 * 2. Redistributions in binary form must reproduce the above copyright notice, 
 *    this list of conditions and the following disclaimer in the documentation 
 *    and/or other materials provided with the distribution. 
 * 3. The name of the author may not be used to endorse or promote products 
 *    derived from this software without specific prior written permission.  
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED  
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF  
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT  
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,  
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT  
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS  
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN  
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING  
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY  
 * OF SUCH DAMAGE. 
 * 
 * This file is part of the lwIP TCP/IP stack. 
 *  
 * Author: Adam Dunkels  
 * 
 */ 
 
#include "lwip/opt.h" 
#include "lwip/ip_addr.h" 
#include "lwip/inet.h" 
#include "lwip/netif.h" 
 
#define IP_ADDR_ANY_VALUE 0x00000000UL 
#define IP_ADDR_BROADCAST_VALUE 0xffffffffUL 
 
/* used by IP_ADDR_ANY and IP_ADDR_BROADCAST in ip_addr.h */ 
const struct ip_addr ip_addr_any = { IP_ADDR_ANY_VALUE }; 
const struct ip_addr ip_addr_broadcast = { IP_ADDR_BROADCAST_VALUE }; 
 
/** 
 * Determine if an address is a broadcast address on a network interface  
 *  
 * @param addr address to be checked 
 * @param netif the network interface against which the address is checked 
 * @return returns non-zero if the address is a broadcast address 
 */ 
u8_t ip_addr_isbroadcast(struct ip_addr *addr, struct netif *netif) 
{ 
  u32_t addr2test; 
 
  addr2test = addr->addr; 
  /* all ones (broadcast) or all zeroes (old skool broadcast) */ 
  if ((~addr2test == IP_ADDR_ANY_VALUE) || 
      (addr2test == IP_ADDR_ANY_VALUE)) 
    return 1; 
  /* no broadcast support on this network interface? */ 
  else if ((netif->flags & NETIF_FLAG_BROADCAST) == 0) 
    /* the given address cannot be a broadcast address 
     * nor can we check against any broadcast addresses */ 
    return 0; 
  /* address matches network interface address exactly? => no broadcast */ 
  else if (addr2test == netif->ip_addr.addr) 
    return 0; 
  /*  on the same (sub) network... */ 
  else if (ip_addr_netcmp(addr, &(netif->ip_addr), &(netif->netmask)) 
         /* ...and host identifier bits are all ones? =>... */ 
          && ((addr2test & ~netif->netmask.addr) == 
           (IP_ADDR_BROADCAST_VALUE & ~netif->netmask.addr))) 
    /* => network broadcast address */ 
    return 1; 
  else 
    return 0; 
}