net/inet/devinet.c

/* */
This source file includes following definitions.
ip_get_mask
ip_chk_addr
ip_my_addr
ip_dev_check
   1 /*
   2  *      NET3    IP device support routines.
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  *      Derived from the IP parts of dev.c 1.0.19
  10  *              Authors:        Ross Biro, <bir7@leland.Stanford.Edu>
  11  *                              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  12  *                              Mark Evans, <evansmp@uhura.aston.ac.uk>
  13  *
  14  *      Additional Authors:
  15  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  16  */
  17  
  18 #include <asm/segment.h>
  19 #include <asm/system.h>
  20 #include <asm/bitops.h>
  21 #include <linux/types.h>
  22 #include <linux/kernel.h>
  23 #include <linux/sched.h>
  24 #include <linux/string.h>
  25 #include <linux/mm.h>
  26 #include <linux/socket.h>
  27 #include <linux/sockios.h>
  28 #include <linux/in.h>
  29 #include <linux/errno.h>
  30 #include <linux/interrupt.h>
  31 #include <linux/if_ether.h>
  32 #include <linux/inet.h>
  33 #include <linux/netdevice.h>
  34 #include <linux/etherdevice.h>
  35 #include "ip.h"
  36 #include "route.h"
  37 #include "protocol.h"
  38 #include "tcp.h"
  39 #include <linux/skbuff.h>
  40 #include "sock.h"
  41 #include "arp.h"
  42 
  43 /* 
  44  *      Determine a default network mask, based on the IP address. 
  45  */
  46  
  47 unsigned long ip_get_mask(unsigned long addr)
     /*  */
  48 {
  49         unsigned long dst;
  50 
  51         if (addr == 0L) 
  52                 return(0L);     /* special case */
  53 
  54         dst = ntohl(addr);
  55         if (IN_CLASSA(dst)) 
  56                 return(htonl(IN_CLASSA_NET));
  57         if (IN_CLASSB(dst)) 
  58                 return(htonl(IN_CLASSB_NET));
  59         if (IN_CLASSC(dst)) 
  60                 return(htonl(IN_CLASSC_NET));
  61   
  62         /*
  63          *      Something else, probably a multicast. 
  64          */
  65          
  66         return(0);
  67 }
  68 
  69 /* 
  70  *      Check the address for our address, broadcasts, etc. 
  71  *
  72  *      I intend to fix this to at the very least cache the last
  73  *      resolved entry.
  74  */
  75  
  76 int ip_chk_addr(unsigned long addr)
     /*  */
  77 {
  78         struct device *dev;
  79         unsigned long mask;
  80 
  81         /* 
  82          *      Accept both `all ones' and `all zeros' as BROADCAST. 
  83          *      (Support old BSD in other words). This old BSD 
  84          *      support will go very soon as it messes other things
  85          *      up.
  86          *      Also accept `loopback broadcast' as BROADCAST.
  87          */
  88 
  89         if (addr == INADDR_ANY || addr == INADDR_BROADCAST ||
  90             addr == htonl(0x7FFFFFFFL))
  91                 return IS_BROADCAST;
  92 
  93         mask = ip_get_mask(addr);
  94 
  95         /*
  96          *      Accept all of the `loopback' class A net. 
  97          */
  98          
  99         if ((addr & mask) == htonl(0x7F000000L))
 100                 return IS_MYADDR;
 101 
 102         /*
 103          *      OK, now check the interface addresses. 
 104          */
 105          
 106         for (dev = dev_base; dev != NULL; dev = dev->next) 
 107         {
 108                 if (!(dev->flags & IFF_UP))
 109                         continue;
 110                 /*
 111                  *      If the protocol address of the device is 0 this is special
 112                  *      and means we are address hunting (eg bootp).
 113                  */
 114                  
 115                 if ((dev->pa_addr == 0)/* || (dev->flags&IFF_PROMISC)*/)
 116                         return IS_MYADDR;
 117                 /*
 118                  *      Is it the exact IP address? 
 119                  */
 120                  
 121                 if (addr == dev->pa_addr)
 122                         return IS_MYADDR;
 123                 /*
 124                  *      Is it our broadcast address? 
 125                  */
 126                  
 127                 if ((dev->flags & IFF_BROADCAST) && addr == dev->pa_brdaddr)
 128                         return IS_BROADCAST;
 129                 /*
 130                  *      Nope. Check for a subnetwork broadcast. 
 131                  */
 132                  
 133                 if (((addr ^ dev->pa_addr) & dev->pa_mask) == 0) 
 134                 {
 135                         if ((addr & ~dev->pa_mask) == 0)
 136                                 return IS_BROADCAST;
 137                         if ((addr & ~dev->pa_mask) == ~dev->pa_mask)
 138                                 return IS_BROADCAST;
 139                 }
 140                 
 141                 /*
 142                  *      Nope. Check for Network broadcast. 
 143                  */
 144                  
 145                 if (((addr ^ dev->pa_addr) & mask) == 0) 
 146                 {
 147                         if ((addr & ~mask) == 0)
 148                                 return IS_BROADCAST;
 149                         if ((addr & ~mask) == ~mask)
 150                                 return IS_BROADCAST;
 151                 }
 152         }
 153         if(IN_MULTICAST(ntohl(addr)))
 154                 return IS_MULTICAST;
 155         return 0;               /* no match at all */
 156 }
 157 
 158 
 159 /*
 160  *      Retrieve our own address.
 161  *
 162  *      Because the loopback address (127.0.0.1) is already recognized
 163  *      automatically, we can use the loopback interface's address as
 164  *      our "primary" interface.  This is the address used by IP et
 165  *      al when it doesn't know which address to use (i.e. it does not
 166  *      yet know from or to which interface to go...).
 167  */
 168  
 169 unsigned long ip_my_addr(void)
     /*  */
 170 {
 171         struct device *dev;
 172 
 173         for (dev = dev_base; dev != NULL; dev = dev->next) 
 174         {
 175                 if (dev->flags & IFF_LOOPBACK) 
 176                         return(dev->pa_addr);
 177         }
 178         return(0);
 179 }
 180 
 181 /*
 182  *      Find an interface that can handle addresses for a certain address. 
 183  *
 184  *      This needs optimising, since its relatively trivial to collapse
 185  *      the two loops into one.
 186  */
 187  
 188 struct device * ip_dev_check(unsigned long addr)
     /*  */
 189 {
 190         struct device *dev;
 191 
 192         for (dev = dev_base; dev; dev = dev->next) 
 193         {
 194                 if (!(dev->flags & IFF_UP))
 195                         continue;
 196                 if (!(dev->flags & IFF_POINTOPOINT))
 197                         continue;
 198                 if (addr != dev->pa_dstaddr)
 199                         continue;
 200                 return dev;
 201         }
 202         for (dev = dev_base; dev; dev = dev->next) 
 203         {
 204                 if (!(dev->flags & IFF_UP))
 205                         continue;
 206                 if (dev->flags & IFF_POINTOPOINT)
 207                         continue;
 208                 if (dev->pa_mask & (addr ^ dev->pa_addr))
 209                         continue;
 210                 return dev;
 211         }
 212         return NULL;
 213 }
/* */
root/net/inet/devinet.c

DEFINITIONS
