net/inet/route.c

/* */
This source file includes following definitions.
rt_print
rt_del
rt_flush
guess_mask
get_gw_dev
rt_add
rt_new
rt_kill
rt_get_info
rt_route
rt_ioctl
   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              ROUTE - implementation of the IP router.
   7  *
   8  * Version:     @(#)route.c     1.0.14  05/31/93
   9  *
  10  * Authors:     Ross Biro, <bir7@leland.Stanford.Edu>
  11  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  12  *
  13  * Fixes:
  14  *              Alan Cox        :       Verify area fixes.
  15  *              Alan Cox        :       cli() protects routing changes
  16  *              Rui Oliveira    :       ICMP routing table updates
  17  *              (rco@di.uminho.pt)      Routing table insertion and update
  18  *
  19  *              This program is free software; you can redistribute it and/or
  20  *              modify it under the terms of the GNU General Public License
  21  *              as published by the Free Software Foundation; either version
  22  *              2 of the License, or (at your option) any later version.
  23  */
  24 #include <asm/segment.h>
  25 #include <asm/system.h>
  26 #include <linux/types.h>
  27 #include <linux/kernel.h>
  28 #include <linux/sched.h>
  29 #include <linux/string.h>
  30 #include <linux/socket.h>
  31 #include <linux/sockios.h>
  32 #include <linux/errno.h>
  33 #include <linux/in.h>
  34 #include "inet.h"
  35 #include "dev.h"
  36 #include "ip.h"
  37 #include "protocol.h"
  38 #include "route.h"
  39 #include "tcp.h"
  40 #include "skbuff.h"
  41 #include "sock.h"
  42 #include "arp.h"
  43 #include "icmp.h"
  44 
  45 
  46 static struct rtable *rt_base = NULL;
  47 
  48 
  49 /* Dump the contents of a routing table entry. */
  50 static void
  51 rt_print(struct rtable *rt)
     /*  */
  52 {
  53   if (rt == NULL || inet_debug != DBG_RT) return;
  54 
  55   printk("RT: %06lx NXT=%06lx FLAGS=0x%02x\n",
  56                 (long) rt, (long) rt->rt_next, rt->rt_flags);
  57   printk("    TARGET=%s ", in_ntoa(rt->rt_dst));
  58   printk("GW=%s ", in_ntoa(rt->rt_gateway));
  59   printk("    DEV=%s USE=%ld REF=%d\n",
  60         (rt->rt_dev == NULL) ? "NONE" : rt->rt_dev->name,
  61         rt->rt_use, rt->rt_refcnt);
  62 }
  63 
  64 
  65 /*
  66  * Remove a routing table entry.
  67  */
  68 static void rt_del(unsigned long dst)
     /*  */
  69 {
  70         struct rtable *r, **rp;
  71         unsigned long flags;
  72 
  73         DPRINTF((DBG_RT, "RT: flushing for dst %s\n", in_ntoa(dst)));
  74         rp = &rt_base;
  75         save_flags(flags);
  76         cli();
  77         while((r = *rp) != NULL) {
  78                 if (r->rt_dst != dst) {
  79                         rp = &r->rt_next;
  80                         continue;
  81                 }
  82                 *rp = r->rt_next;
  83                 kfree_s(r, sizeof(struct rtable));
  84         } 
  85         restore_flags(flags);
  86 }
  87 
  88 
  89 /*
  90  * Remove all routing table entries for a device.
  91  */
  92 void rt_flush(struct device *dev)
     /*  */
  93 {
  94         struct rtable *r;
  95         struct rtable **rp;
  96         unsigned long flags;
  97 
  98         DPRINTF((DBG_RT, "RT: flushing for dev 0x%08lx (%s)\n", (long)dev, dev->name));
  99         rp = &rt_base;
 100         cli();
 101         save_flags(flags);
 102         while ((r = *rp) != NULL) {
 103                 if (r->rt_dev != dev) {
 104                         rp = &r->rt_next;
 105                         continue;
 106                 }
 107                 *rp = r->rt_next;
 108                 kfree_s(r, sizeof(struct rtable));
 109         } 
 110         restore_flags(flags);
 111 }
 112 
 113 /*
 114  * Used by 'rt_add()' when we can't get the netmask from the device..
 115  *
 116  * If the lower byte or two are zero, we guess the mask based on the
 117  * number of zero 8-bit net numbers, otherwise we use the "default"
 118  * masks judging by the destination address.
 119  *
 120  * We should really use masks everywhere, but the current system
 121  * interface for adding routes doesn't even contain a netmask field.
 122  * Similarly, ICMP redirect messages contain only the address to
 123  * redirect.. Anyway, this function should give reasonable values
 124  * for almost anything.
 125  */
 126 static unsigned long guess_mask(unsigned long dst)
     /*  */
 127 {
 128         unsigned long mask = 0xffffffff;
 129 
 130         while (mask & dst)
 131                 mask <<= 8;
 132         if (mask)
 133                 return ~mask;
 134         dst = ntohl(dst);
 135         if (IN_CLASSA(dst))
 136                 return htonl(IN_CLASSA_NET);
 137         if (IN_CLASSB(dst))
 138                 return htonl(IN_CLASSB_NET);
 139         return htonl(IN_CLASSC_NET);
 140 }
 141 
 142 static inline struct device * get_gw_dev(unsigned long gw)
     /*  */
 143 {
 144         struct rtable * rt;
 145 
 146         for (rt = rt_base ; rt ; rt = rt->rt_next) {
 147                 if ((gw ^ rt->rt_dst) & rt->rt_mask)
 148                         continue;
 149                 /* gateways behind gateways are a no-no */
 150                 if (rt->rt_flags & RTF_GATEWAY)
 151                         return NULL;
 152                 return rt->rt_dev;
 153         }
 154         return NULL;
 155 }
 156 
 157 /*
 158  * rewrote rt_add(), as the old one was weird. Linus
 159  */
 160 void
 161 rt_add(short flags, unsigned long dst, unsigned long gw, struct device *dev)
     /*  */
 162 {
 163         struct rtable *r, *rt;
 164         struct rtable **rp;
 165         unsigned long mask;
 166         unsigned long cpuflags;
 167 
 168         if (flags & RTF_HOST) {
 169                 mask = 0xffffffff;
 170         } else {
 171                 if (!((dst ^ dev->pa_addr) & dev->pa_mask)) {
 172                         mask = dev->pa_mask;
 173                         dst &= mask;
 174                         flags &= ~RTF_GATEWAY;
 175                         if (flags & RTF_DYNAMIC) {
 176                                 /*printk("Dynamic route to my own net rejected\n");*/
 177                                 return;
 178                         }
 179                 } else
 180                         mask = guess_mask(dst);
 181         }
 182         if (gw == dev->pa_addr)
 183                 flags &= ~RTF_GATEWAY;
 184         if (flags & RTF_GATEWAY) {
 185                 /* don't try to add a gateway we can't reach.. */
 186                 if (dev != get_gw_dev(gw))
 187                         return;
 188                 flags |= RTF_GATEWAY;
 189         } else
 190                 gw = 0;
 191         /* Allocate an entry. */
 192         rt = (struct rtable *) kmalloc(sizeof(struct rtable), GFP_ATOMIC);
 193         if (rt == NULL) {
 194                 DPRINTF((DBG_RT, "RT: no memory for new route!\n"));
 195                 return;
 196         }
 197         memset(rt, 0, sizeof(struct rtable));
 198         rt->rt_flags = flags | RTF_UP;
 199         rt->rt_dst = dst;
 200         rt->rt_dev = dev;
 201         rt->rt_gateway = gw;
 202         rt->rt_mask = mask;
 203         rt_print(rt);
 204         /*
 205          * What we have to do is loop though this until we have
 206          * found the first address which has a higher generality than
 207          * the one in rt.  Then we can put rt in right before it.
 208          */
 209         save_flags(cpuflags);
 210         cli();
 211         /* remove old route if we are getting a duplicate. */
 212         rp = &rt_base;
 213         while ((r = *rp) != NULL) {
 214                 if (r->rt_dst != dst) {
 215                         rp = &r->rt_next;
 216                         continue;
 217                 }
 218                 *rp = r->rt_next;
 219                 kfree_s(r, sizeof(struct rtable));
 220         }
 221         /* add the new route */
 222         rp = &rt_base;
 223         while ((r = *rp) != NULL) {
 224                 if ((r->rt_mask & mask) != mask)
 225                         break;
 226                 rp = &r->rt_next;
 227         }
 228         rt->rt_next = r;
 229         *rp = rt;
 230         restore_flags(cpuflags);
 231         return;
 232 }
 233 
 234 
 235 static int
 236 rt_new(struct rtentry *r)
     /*  */
 237 {
 238   struct device *dev;
 239 
 240   if ((r->rt_dst.sa_family != AF_INET) ||
 241       (r->rt_gateway.sa_family != AF_INET)) {
 242         DPRINTF((DBG_RT, "RT: We only know about AF_INET !\n"));
 243         return(-EAFNOSUPPORT);
 244   }
 245 
 246   /*
 247    * I admit that the following bits of code were "inspired" by
 248    * the Berkeley UNIX system source code.  I could think of no
 249    * other way to find out how to make it compatible with it (I
 250    * want this to be compatible to get "routed" up and running).
 251    * -FvK
 252    */
 253 
 254   /* If we have a 'gateway' route here, check the correct address. */
 255   if (!(r->rt_flags & RTF_GATEWAY))
 256         dev = dev_check(((struct sockaddr_in *) &r->rt_dst)->sin_addr.s_addr);
 257   else
 258         dev = get_gw_dev(((struct sockaddr_in *) &r->rt_gateway)->sin_addr.s_addr);
 259 
 260   DPRINTF((DBG_RT, "RT: dev for %s gw ",
 261         in_ntoa((*(struct sockaddr_in *)&r->rt_dst).sin_addr.s_addr)));
 262   DPRINTF((DBG_RT, "%s (0x%04X) is 0x%X (%s)\n",
 263         in_ntoa((*(struct sockaddr_in *)&r->rt_gateway).sin_addr.s_addr),
 264         r->rt_flags, dev, (dev == NULL) ? "NONE" : dev->name));
 265 
 266   if (dev == NULL) return(-ENETUNREACH);
 267 
 268   rt_add(r->rt_flags, (*(struct sockaddr_in *) &r->rt_dst).sin_addr.s_addr,
 269          (*(struct sockaddr_in *) &r->rt_gateway).sin_addr.s_addr, dev);
 270 
 271   return(0);
 272 }
 273 
 274 
 275 static int
 276 rt_kill(struct rtentry *r)
     /*  */
 277 {
 278   struct sockaddr_in *trg;
 279 
 280   trg = (struct sockaddr_in *) &r->rt_dst;
 281   rt_del(trg->sin_addr.s_addr);
 282 
 283   return(0);
 284 }
 285 
 286 
 287 /* Called from the PROCfs module. */
 288 int
 289 rt_get_info(char *buffer)
     /*  */
 290 {
 291   struct rtable *r;
 292   char *pos;
 293 
 294   pos = buffer;
 295 
 296   pos += sprintf(pos,
 297                  "Iface\tDestination\tGateway \tFlags\tRefCnt\tUse\tMetric\tMask\n");
 298   
 299   /* This isn't quite right -- r->rt_dst is a struct! */
 300   for (r = rt_base; r != NULL; r = r->rt_next) {
 301         pos += sprintf(pos, "%s\t%08lX\t%08lX\t%02X\t%d\t%lu\t%d\t%08lX\n",
 302                 r->rt_dev->name, r->rt_dst, r->rt_gateway,
 303                 r->rt_flags, r->rt_refcnt, r->rt_use, r->rt_metric,
 304                 r->rt_mask);
 305   }
 306   return(pos - buffer);
 307 }
 308 
 309 
 310 /*
 311  * rewrote this too.. Maybe somebody can understand it now. Linus
 312  */
 313 struct rtable * rt_route(unsigned long daddr, struct options *opt)
     /*  */
 314 {
 315         struct rtable *rt;
 316         int type;
 317 
 318   /*
 319    * This is a hack, I think. -FvK
 320    */
 321         if ((type=chk_addr(daddr)) == IS_MYADDR) daddr = my_addr();
 322 
 323   /*
 324    * Loop over the IP routing table to find a route suitable
 325    * for this packet.  Note that we really should have a look
 326    * at the IP options to see if we have been given a hint as
 327    * to what kind of path we should use... -FvK
 328    */
 329   /*
 330    * This depends on 'rt_mask' and the ordering set up in 'rt_add()' - Linus
 331    */
 332         for (rt = rt_base; rt != NULL; rt = rt->rt_next) {
 333                 if (!((rt->rt_dst ^ daddr) & rt->rt_mask)) {
 334                         rt->rt_use++;
 335                         return rt;
 336                 }
 337                 /* broadcast addresses can be special cases.. */
 338                 if ((rt->rt_dev->flags & IFF_BROADCAST) &&
 339                      rt->rt_dev->pa_brdaddr == daddr) {
 340                         rt->rt_use++;
 341                         return(rt);
 342                 }
 343         }
 344         return NULL;
 345 }
 346 
 347 
 348 int
 349 rt_ioctl(unsigned int cmd, void *arg)
     /*  */
 350 {
 351   struct device *dev;
 352   struct rtentry rt;
 353   char namebuf[32];
 354   int ret;
 355   int err;
 356 
 357   switch(cmd) {
 358         case DDIOCSDBG:
 359                 ret = dbg_ioctl(arg, DBG_RT);
 360                 break;
 361         case SIOCADDRT:
 362         case SIOCDELRT:
 363                 if (!suser()) return(-EPERM);
 364                 err=verify_area(VERIFY_READ, arg, sizeof(struct rtentry));
 365                 if(err)
 366                         return err;
 367                 memcpy_fromfs(&rt, arg, sizeof(struct rtentry));
 368                 if (rt.rt_dev) {
 369                     err=verify_area(VERIFY_READ, rt.rt_dev, sizeof namebuf);
 370                     if(err)
 371                         return err;
 372                     memcpy_fromfs(&namebuf, rt.rt_dev, sizeof namebuf);
 373                     dev = dev_get(namebuf);
 374                     rt.rt_dev = dev;
 375                 }
 376                 ret = (cmd == SIOCDELRT) ? rt_kill(&rt) : rt_new(&rt);
 377                 break;
 378         default:
 379                 ret = -EINVAL;
 380   }
 381 
 382   return(ret);
 383 }
/* */
root/net/inet/route.c

DEFINITIONS
