ip_addr.c

00001 /**
00002  * @file
00003  * This is the IPv4 address tools implementation.
00004  *
00005  */
00006 
00007 /*
00008  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
00009  * All rights reserved. 
00010  * 
00011  * Redistribution and use in source and binary forms, with or without modification, 
00012  * are permitted provided that the following conditions are met:
00013  *
00014  * 1. Redistributions of source code must retain the above copyright notice,
00015  *    this list of conditions and the following disclaimer.
00016  * 2. Redistributions in binary form must reproduce the above copyright notice,
00017  *    this list of conditions and the following disclaimer in the documentation
00018  *    and/or other materials provided with the distribution.
00019  * 3. The name of the author may not be used to endorse or promote products
00020  *    derived from this software without specific prior written permission. 
00021  *
00022  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
00023  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
00024  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
00025  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
00026  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
00027  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
00028  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
00029  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
00030  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
00031  * OF SUCH DAMAGE.
00032  *
00033  * This file is part of the lwIP TCP/IP stack.
00034  * 
00035  * Author: Adam Dunkels <adam@sics.se>
00036  *
00037  */
00038 
00039 #include "lwip/opt.h"
00040 #include "lwip/ip_addr.h"
00041 #include "lwip/inet.h"
00042 #include "lwip/netif.h"
00043 
00044 #define IP_ADDR_ANY_VALUE 0x00000000UL
00045 #define IP_ADDR_BROADCAST_VALUE 0xffffffffUL
00046 
00047 /* used by IP_ADDR_ANY and IP_ADDR_BROADCAST in ip_addr.h */
00048 const struct ip_addr ip_addr_any = { IP_ADDR_ANY_VALUE };
00049 const struct ip_addr ip_addr_broadcast = { IP_ADDR_BROADCAST_VALUE };
00050 
00051 /**
00052  * Determine if an address is a broadcast address on a network interface 
00053  * 
00054  * @param addr address to be checked
00055  * @param netif the network interface against which the address is checked
00056  * @return returns non-zero if the address is a broadcast address
00057  */
00058 u8_t ip_addr_isbroadcast(struct ip_addr *addr, struct netif *netif)
00059 {
00060   u32_t addr2test;
00061 
00062   addr2test = addr->addr;
00063   /* all ones (broadcast) or all zeroes (old skool broadcast) */
00064   if ((~addr2test == IP_ADDR_ANY_VALUE) ||
00065       (addr2test == IP_ADDR_ANY_VALUE))
00066     return 1;
00067   /* no broadcast support on this network interface? */
00068   else if ((netif->flags & NETIF_FLAG_BROADCAST) == 0)
00069     /* the given address cannot be a broadcast address
00070      * nor can we check against any broadcast addresses */
00071     return 0;
00072   /* address matches network interface address exactly? => no broadcast */
00073   else if (addr2test == netif->ip_addr.addr)
00074     return 0;
00075   /*  on the same (sub) network... */
00076   else if (ip_addr_netcmp(addr, &(netif->ip_addr), &(netif->netmask))
00077          /* ...and host identifier bits are all ones? =>... */
00078           && ((addr2test & ~netif->netmask.addr) ==
00079            (IP_ADDR_BROADCAST_VALUE & ~netif->netmask.addr)))
00080     /* => network broadcast address */
00081     return 1;
00082   else
00083     return 0;
00084 }