git.oblomov.eu Git - linux-2.6/blob - net/ipv4/ip_options.c

   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  *              The options processing module for ip.c
   7  *
   8  * Version:     $Id: ip_options.c,v 1.21 2001/09/01 00:31:50 davem Exp $
   9  *
  10  * Authors:     A.N.Kuznetsov
  11  *
  12  */
  13
  14 #include <linux/capability.h>
  15 #include <linux/module.h>
  16 #include <linux/types.h>
  17 #include <asm/uaccess.h>
  18 #include <linux/skbuff.h>
  19 #include <linux/ip.h>
  20 #include <linux/icmp.h>
  21 #include <linux/netdevice.h>
  22 #include <linux/rtnetlink.h>
  23 #include <net/sock.h>
  24 #include <net/ip.h>
  25 #include <net/icmp.h>
  26 #include <net/route.h>
  27 #include <net/cipso_ipv4.h>
  28
  29 /*
  30  * Write options to IP header, record destination address to
  31  * source route option, address of outgoing interface
  32  * (we should already know it, so that this  function is allowed be
  33  * called only after routing decision) and timestamp,
  34  * if we originate this datagram.
  35  *
  36  * daddr is real destination address, next hop is recorded in IP header.
  37  * saddr is address of outgoing interface.
  38  */
  39
  40 void ip_options_build(struct sk_buff * skb, struct ip_options * opt,
  41                             __be32 daddr, struct rtable *rt, int is_frag)
  42 {
  43         unsigned char *iph = skb_network_header(skb);
  44
  45         memcpy(&(IPCB(skb)->opt), opt, sizeof(struct ip_options));
  46         memcpy(iph+sizeof(struct iphdr), opt->__data, opt->optlen);
  47         opt = &(IPCB(skb)->opt);
  48
  49         if (opt->srr)
  50                 memcpy(iph+opt->srr+iph[opt->srr+1]-4, &daddr, 4);
  51
  52         if (!is_frag) {
  53                 if (opt->rr_needaddr)
  54                         ip_rt_get_source(iph+opt->rr+iph[opt->rr+2]-5, rt);
  55                 if (opt->ts_needaddr)
  56                         ip_rt_get_source(iph+opt->ts+iph[opt->ts+2]-9, rt);
  57                 if (opt->ts_needtime) {
  58                         struct timespec tv;
  59                         __be32 midtime;
  60                         getnstimeofday(&tv);
  61                         midtime = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + tv.tv_nsec / NSEC_PER_MSEC);
  62                         memcpy(iph+opt->ts+iph[opt->ts+2]-5, &midtime, 4);
  63                 }
  64                 return;
  65         }
  66         if (opt->rr) {
  67                 memset(iph+opt->rr, IPOPT_NOP, iph[opt->rr+1]);
  68                 opt->rr = 0;
  69                 opt->rr_needaddr = 0;
  70         }
  71         if (opt->ts) {
  72                 memset(iph+opt->ts, IPOPT_NOP, iph[opt->ts+1]);
  73                 opt->ts = 0;
  74                 opt->ts_needaddr = opt->ts_needtime = 0;
  75         }
  76 }
  77
  78 /*
  79  * Provided (sopt, skb) points to received options,
  80  * build in dopt compiled option set appropriate for answering.
  81  * i.e. invert SRR option, copy anothers,
  82  * and grab room in RR/TS options.
  83  *
  84  * NOTE: dopt cannot point to skb.
  85  */
  86
  87 int ip_options_echo(struct ip_options * dopt, struct sk_buff * skb)
  88 {
  89         struct ip_options *sopt;
  90         unsigned char *sptr, *dptr;
  91         int soffset, doffset;
  92         int     optlen;
  93         __be32  daddr;
  94
  95         memset(dopt, 0, sizeof(struct ip_options));
  96
  97         sopt = &(IPCB(skb)->opt);
  98
  99         if (sopt->optlen == 0) {
 100                 dopt->optlen = 0;
 101                 return 0;
 102         }
 103
 104         sptr = skb_network_header(skb);
 105         dptr = dopt->__data;
 106
 107         daddr = skb->rtable->rt_spec_dst;
 108
 109         if (sopt->rr) {
 110                 optlen  = sptr[sopt->rr+1];
 111                 soffset = sptr[sopt->rr+2];
 112                 dopt->rr = dopt->optlen + sizeof(struct iphdr);
 113                 memcpy(dptr, sptr+sopt->rr, optlen);
 114                 if (sopt->rr_needaddr && soffset <= optlen) {
 115                         if (soffset + 3 > optlen)
 116                                 return -EINVAL;
 117                         dptr[2] = soffset + 4;
 118                         dopt->rr_needaddr = 1;
 119                 }
 120                 dptr += optlen;
 121                 dopt->optlen += optlen;
 122         }
 123         if (sopt->ts) {
 124                 optlen = sptr[sopt->ts+1];
 125                 soffset = sptr[sopt->ts+2];
 126                 dopt->ts = dopt->optlen + sizeof(struct iphdr);
 127                 memcpy(dptr, sptr+sopt->ts, optlen);
 128                 if (soffset <= optlen) {
 129                         if (sopt->ts_needaddr) {
 130                                 if (soffset + 3 > optlen)
 131                                         return -EINVAL;
 132                                 dopt->ts_needaddr = 1;
 133                                 soffset += 4;
 134                         }
 135                         if (sopt->ts_needtime) {
 136                                 if (soffset + 3 > optlen)
 137                                         return -EINVAL;
 138                                 if ((dptr[3]&0xF) != IPOPT_TS_PRESPEC) {
 139                                         dopt->ts_needtime = 1;
 140                                         soffset += 4;
 141                                 } else {
 142                                         dopt->ts_needtime = 0;
 143
 144                                         if (soffset + 8 <= optlen) {
 145                                                 __be32 addr;
 146
 147                                                 memcpy(&addr, sptr+soffset-1, 4);
 148                                                 if (inet_addr_type(dev_net(skb->dst->dev), addr) != RTN_LOCAL) {
 149                                                         dopt->ts_needtime = 1;
 150                                                         soffset += 8;
 151                                                 }
 152                                         }
 153                                 }
 154                         }
 155                         dptr[2] = soffset;
 156                 }
 157                 dptr += optlen;
 158                 dopt->optlen += optlen;
 159         }
 160         if (sopt->srr) {
 161                 unsigned char * start = sptr+sopt->srr;
 162                 __be32 faddr;
 163
 164                 optlen  = start[1];
 165                 soffset = start[2];
 166                 doffset = 0;
 167                 if (soffset > optlen)
 168                         soffset = optlen + 1;
 169                 soffset -= 4;
 170                 if (soffset > 3) {
 171                         memcpy(&faddr, &start[soffset-1], 4);
 172                         for (soffset-=4, doffset=4; soffset > 3; soffset-=4, doffset+=4)
 173                                 memcpy(&dptr[doffset-1], &start[soffset-1], 4);
 174                         /*
 175                          * RFC1812 requires to fix illegal source routes.
 176                          */
 177                         if (memcmp(&ip_hdr(skb)->saddr,
 178                                    &start[soffset + 3], 4) == 0)
 179                                 doffset -= 4;
 180                 }
 181                 if (doffset > 3) {
 182                         memcpy(&start[doffset-1], &daddr, 4);
 183                         dopt->faddr = faddr;
 184                         dptr[0] = start[0];
 185                         dptr[1] = doffset+3;
 186                         dptr[2] = 4;
 187                         dptr += doffset+3;
 188                         dopt->srr = dopt->optlen + sizeof(struct iphdr);
 189                         dopt->optlen += doffset+3;
 190                         dopt->is_strictroute = sopt->is_strictroute;
 191                 }
 192         }
 193         if (sopt->cipso) {
 194                 optlen  = sptr[sopt->cipso+1];
 195                 dopt->cipso = dopt->optlen+sizeof(struct iphdr);
 196                 memcpy(dptr, sptr+sopt->cipso, optlen);
 197                 dptr += optlen;
 198                 dopt->optlen += optlen;
 199         }
 200         while (dopt->optlen & 3) {
 201                 *dptr++ = IPOPT_END;
 202                 dopt->optlen++;
 203         }
 204         return 0;
 205 }
 206
 207 /*
 208  *      Options "fragmenting", just fill options not
 209  *      allowed in fragments with NOOPs.
 210  *      Simple and stupid 8), but the most efficient way.
 211  */
 212
 213 void ip_options_fragment(struct sk_buff * skb)
 214 {
 215         unsigned char *optptr = skb_network_header(skb) + sizeof(struct iphdr);
 216         struct ip_options * opt = &(IPCB(skb)->opt);
 217         int  l = opt->optlen;
 218         int  optlen;
 219
 220         while (l > 0) {
 221                 switch (*optptr) {
 222                 case IPOPT_END:
 223                         return;
 224                 case IPOPT_NOOP:
 225                         l--;
 226                         optptr++;
 227                         continue;
 228                 }
 229                 optlen = optptr[1];
 230                 if (optlen<2 || optlen>l)
 231                   return;
 232                 if (!IPOPT_COPIED(*optptr))
 233                         memset(optptr, IPOPT_NOOP, optlen);
 234                 l -= optlen;
 235                 optptr += optlen;
 236         }
 237         opt->ts = 0;
 238         opt->rr = 0;
 239         opt->rr_needaddr = 0;
 240         opt->ts_needaddr = 0;
 241         opt->ts_needtime = 0;
 242         return;
 243 }
 244
 245 /*
 246  * Verify options and fill pointers in struct options.
 247  * Caller should clear *opt, and set opt->data.
 248  * If opt == NULL, then skb->data should point to IP header.
 249  */
 250
 251 int ip_options_compile(struct net *net,
 252                        struct ip_options * opt, struct sk_buff * skb)
 253 {
 254         int l;
 255         unsigned char * iph;
 256         unsigned char * optptr;
 257         int optlen;
 258         unsigned char * pp_ptr = NULL;
 259         struct rtable *rt = NULL;
 260
 261         if (skb != NULL) {
 262                 rt = skb->rtable;
 263                 optptr = (unsigned char *)&(ip_hdr(skb)[1]);
 264         } else
 265                 optptr = opt->__data;
 266         iph = optptr - sizeof(struct iphdr);
 267
 268         for (l = opt->optlen; l > 0; ) {
 269                 switch (*optptr) {
 270                       case IPOPT_END:
 271                         for (optptr++, l--; l>0; optptr++, l--) {
 272                                 if (*optptr != IPOPT_END) {
 273                                         *optptr = IPOPT_END;
 274                                         opt->is_changed = 1;
 275                                 }
 276                         }
 277                         goto eol;
 278                       case IPOPT_NOOP:
 279                         l--;
 280                         optptr++;
 281                         continue;
 282                 }
 283                 optlen = optptr[1];
 284                 if (optlen<2 || optlen>l) {
 285                         pp_ptr = optptr;
 286                         goto error;
 287                 }
 288                 switch (*optptr) {
 289                       case IPOPT_SSRR:
 290                       case IPOPT_LSRR:
 291                         if (optlen < 3) {
 292                                 pp_ptr = optptr + 1;
 293                                 goto error;
 294                         }
 295                         if (optptr[2] < 4) {
 296                                 pp_ptr = optptr + 2;
 297                                 goto error;
 298                         }
 299                         /* NB: cf RFC-1812 5.2.4.1 */
 300                         if (opt->srr) {
 301                                 pp_ptr = optptr;
 302                                 goto error;
 303                         }
 304                         if (!skb) {
 305                                 if (optptr[2] != 4 || optlen < 7 || ((optlen-3) & 3)) {
 306                                         pp_ptr = optptr + 1;
 307                                         goto error;
 308                                 }
 309                                 memcpy(&opt->faddr, &optptr[3], 4);
 310                                 if (optlen > 7)
 311                                         memmove(&optptr[3], &optptr[7], optlen-7);
 312                         }
 313                         opt->is_strictroute = (optptr[0] == IPOPT_SSRR);
 314                         opt->srr = optptr - iph;
 315                         break;
 316                       case IPOPT_RR:
 317                         if (opt->rr) {
 318                                 pp_ptr = optptr;
 319                                 goto error;
 320                         }
 321                         if (optlen < 3) {
 322                                 pp_ptr = optptr + 1;
 323                                 goto error;
 324                         }
 325                         if (optptr[2] < 4) {
 326                                 pp_ptr = optptr + 2;
 327                                 goto error;
 328                         }
 329                         if (optptr[2] <= optlen) {
 330                                 if (optptr[2]+3 > optlen) {
 331                                         pp_ptr = optptr + 2;
 332                                         goto error;
 333                                 }
 334                                 if (skb) {
 335                                         memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
 336                                         opt->is_changed = 1;
 337                                 }
 338                                 optptr[2] += 4;
 339                                 opt->rr_needaddr = 1;
 340                         }
 341                         opt->rr = optptr - iph;
 342                         break;
 343                       case IPOPT_TIMESTAMP:
 344                         if (opt->ts) {
 345                                 pp_ptr = optptr;
 346                                 goto error;
 347                         }
 348                         if (optlen < 4) {
 349                                 pp_ptr = optptr + 1;
 350                                 goto error;
 351                         }
 352                         if (optptr[2] < 5) {
 353                                 pp_ptr = optptr + 2;
 354                                 goto error;
 355                         }
 356                         if (optptr[2] <= optlen) {
 357                                 __be32 *timeptr = NULL;
 358                                 if (optptr[2]+3 > optptr[1]) {
 359                                         pp_ptr = optptr + 2;
 360                                         goto error;
 361                                 }
 362                                 switch (optptr[3]&0xF) {
 363                                       case IPOPT_TS_TSONLY:
 364                                         opt->ts = optptr - iph;
 365                                         if (skb)
 366                                                 timeptr = (__be32*)&optptr[optptr[2]-1];
 367                                         opt->ts_needtime = 1;
 368                                         optptr[2] += 4;
 369                                         break;
 370                                       case IPOPT_TS_TSANDADDR:
 371                                         if (optptr[2]+7 > optptr[1]) {
 372                                                 pp_ptr = optptr + 2;
 373                                                 goto error;
 374                                         }
 375                                         opt->ts = optptr - iph;
 376                                         if (skb) {
 377                                                 memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
 378                                                 timeptr = (__be32*)&optptr[optptr[2]+3];
 379                                         }
 380                                         opt->ts_needaddr = 1;
 381                                         opt->ts_needtime = 1;
 382                                         optptr[2] += 8;
 383                                         break;
 384                                       case IPOPT_TS_PRESPEC:
 385                                         if (optptr[2]+7 > optptr[1]) {
 386                                                 pp_ptr = optptr + 2;
 387                                                 goto error;
 388                                         }
 389                                         opt->ts = optptr - iph;
 390                                         {
 391                                                 __be32 addr;
 392                                                 memcpy(&addr, &optptr[optptr[2]-1], 4);
 393                                                 if (inet_addr_type(net, addr) == RTN_UNICAST)
 394                                                         break;
 395                                                 if (skb)
 396                                                         timeptr = (__be32*)&optptr[optptr[2]+3];
 397                                         }
 398                                         opt->ts_needtime = 1;
 399                                         optptr[2] += 8;
 400                                         break;
 401                                       default:
 402                                         if (!skb && !capable(CAP_NET_RAW)) {
 403                                                 pp_ptr = optptr + 3;
 404                                                 goto error;
 405                                         }
 406                                         break;
 407                                 }
 408                                 if (timeptr) {
 409                                         struct timespec tv;
 410                                         __be32  midtime;
 411                                         getnstimeofday(&tv);
 412                                         midtime = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + tv.tv_nsec / NSEC_PER_MSEC);
 413                                         memcpy(timeptr, &midtime, sizeof(__be32));
 414                                         opt->is_changed = 1;
 415                                 }
 416                         } else {
 417                                 unsigned overflow = optptr[3]>>4;
 418                                 if (overflow == 15) {
 419                                         pp_ptr = optptr + 3;
 420                                         goto error;
 421                                 }
 422                                 opt->ts = optptr - iph;
 423                                 if (skb) {
 424                                         optptr[3] = (optptr[3]&0xF)|((overflow+1)<<4);
 425                                         opt->is_changed = 1;
 426                                 }
 427                         }
 428                         break;
 429                       case IPOPT_RA:
 430                         if (optlen < 4) {
 431                                 pp_ptr = optptr + 1;
 432                                 goto error;
 433                         }
 434                         if (optptr[2] == 0 && optptr[3] == 0)
 435                                 opt->router_alert = optptr - iph;
 436                         break;
 437                       case IPOPT_CIPSO:
 438                         if ((!skb && !capable(CAP_NET_RAW)) || opt->cipso) {
 439                                 pp_ptr = optptr;
 440                                 goto error;
 441                         }
 442                         opt->cipso = optptr - iph;
 443                         if (cipso_v4_validate(&optptr)) {
 444                                 pp_ptr = optptr;
 445                                 goto error;
 446                         }
 447                         break;
 448                       case IPOPT_SEC:
 449                       case IPOPT_SID:
 450                       default:
 451                         if (!skb && !capable(CAP_NET_RAW)) {
 452                                 pp_ptr = optptr;
 453                                 goto error;
 454                         }
 455                         break;
 456                 }
 457                 l -= optlen;
 458                 optptr += optlen;
 459         }
 460
 461 eol:
 462         if (!pp_ptr)
 463                 return 0;
 464
 465 error:
 466         if (skb) {
 467                 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((pp_ptr-iph)<<24));
 468         }
 469         return -EINVAL;
 470 }
 471
 472
 473 /*
 474  *      Undo all the changes done by ip_options_compile().
 475  */
 476
 477 void ip_options_undo(struct ip_options * opt)
 478 {
 479         if (opt->srr) {
 480                 unsigned  char * optptr = opt->__data+opt->srr-sizeof(struct  iphdr);
 481                 memmove(optptr+7, optptr+3, optptr[1]-7);
 482                 memcpy(optptr+3, &opt->faddr, 4);
 483         }
 484         if (opt->rr_needaddr) {
 485                 unsigned  char * optptr = opt->__data+opt->rr-sizeof(struct  iphdr);
 486                 optptr[2] -= 4;
 487                 memset(&optptr[optptr[2]-1], 0, 4);
 488         }
 489         if (opt->ts) {
 490                 unsigned  char * optptr = opt->__data+opt->ts-sizeof(struct  iphdr);
 491                 if (opt->ts_needtime) {
 492                         optptr[2] -= 4;
 493                         memset(&optptr[optptr[2]-1], 0, 4);
 494                         if ((optptr[3]&0xF) == IPOPT_TS_PRESPEC)
 495                                 optptr[2] -= 4;
 496                 }
 497                 if (opt->ts_needaddr) {
 498                         optptr[2] -= 4;
 499                         memset(&optptr[optptr[2]-1], 0, 4);
 500                 }
 501         }
 502 }
 503
 504 static struct ip_options *ip_options_get_alloc(const int optlen)
 505 {
 506         return kzalloc(sizeof(struct ip_options) + ((optlen + 3) & ~3),
 507                        GFP_KERNEL);
 508 }
 509
 510 static int ip_options_get_finish(struct net *net, struct ip_options **optp,
 511                                  struct ip_options *opt, int optlen)
 512 {
 513         while (optlen & 3)
 514                 opt->__data[optlen++] = IPOPT_END;
 515         opt->optlen = optlen;
 516         if (optlen && ip_options_compile(net, opt, NULL)) {
 517                 kfree(opt);
 518                 return -EINVAL;
 519         }
 520         kfree(*optp);
 521         *optp = opt;
 522         return 0;
 523 }
 524
 525 int ip_options_get_from_user(struct net *net, struct ip_options **optp,
 526                              unsigned char __user *data, int optlen)
 527 {
 528         struct ip_options *opt = ip_options_get_alloc(optlen);
 529
 530         if (!opt)
 531                 return -ENOMEM;
 532         if (optlen && copy_from_user(opt->__data, data, optlen)) {
 533                 kfree(opt);
 534                 return -EFAULT;
 535         }
 536         return ip_options_get_finish(net, optp, opt, optlen);
 537 }
 538
 539 int ip_options_get(struct net *net, struct ip_options **optp,
 540                    unsigned char *data, int optlen)
 541 {
 542         struct ip_options *opt = ip_options_get_alloc(optlen);
 543
 544         if (!opt)
 545                 return -ENOMEM;
 546         if (optlen)
 547                 memcpy(opt->__data, data, optlen);
 548         return ip_options_get_finish(net, optp, opt, optlen);
 549 }
 550
 551 void ip_forward_options(struct sk_buff *skb)
 552 {
 553         struct   ip_options * opt       = &(IPCB(skb)->opt);
 554         unsigned char * optptr;
 555         struct rtable *rt = skb->rtable;
 556         unsigned char *raw = skb_network_header(skb);
 557
 558         if (opt->rr_needaddr) {
 559                 optptr = (unsigned char *)raw + opt->rr;
 560                 ip_rt_get_source(&optptr[optptr[2]-5], rt);
 561                 opt->is_changed = 1;
 562         }
 563         if (opt->srr_is_hit) {
 564                 int srrptr, srrspace;
 565
 566                 optptr = raw + opt->srr;
 567
 568                 for ( srrptr=optptr[2], srrspace = optptr[1];
 569                      srrptr <= srrspace;
 570                      srrptr += 4
 571                      ) {
 572                         if (srrptr + 3 > srrspace)
 573                                 break;
 574                         if (memcmp(&rt->rt_dst, &optptr[srrptr-1], 4) == 0)
 575                                 break;
 576                 }
 577                 if (srrptr + 3 <= srrspace) {
 578                         opt->is_changed = 1;
 579                         ip_rt_get_source(&optptr[srrptr-1], rt);
 580                         ip_hdr(skb)->daddr = rt->rt_dst;
 581                         optptr[2] = srrptr+4;
 582                 } else if (net_ratelimit())
 583                         printk(KERN_CRIT "ip_forward(): Argh! Destination lost!\n");
 584                 if (opt->ts_needaddr) {
 585                         optptr = raw + opt->ts;
 586                         ip_rt_get_source(&optptr[optptr[2]-9], rt);
 587                         opt->is_changed = 1;
 588                 }
 589         }
 590         if (opt->is_changed) {
 591                 opt->is_changed = 0;
 592                 ip_send_check(ip_hdr(skb));
 593         }
 594 }
 595
 596 int ip_options_rcv_srr(struct sk_buff *skb)
 597 {
 598         struct ip_options *opt = &(IPCB(skb)->opt);
 599         int srrspace, srrptr;
 600         __be32 nexthop;
 601         struct iphdr *iph = ip_hdr(skb);
 602         unsigned char *optptr = skb_network_header(skb) + opt->srr;
 603         struct rtable *rt = skb->rtable;
 604         struct rtable *rt2;
 605         int err;
 606
 607         if (!opt->srr)
 608                 return 0;
 609
 610         if (skb->pkt_type != PACKET_HOST)
 611                 return -EINVAL;
 612         if (rt->rt_type == RTN_UNICAST) {
 613                 if (!opt->is_strictroute)
 614                         return 0;
 615                 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl(16<<24));
 616                 return -EINVAL;
 617         }
 618         if (rt->rt_type != RTN_LOCAL)
 619                 return -EINVAL;
 620
 621         for (srrptr=optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4) {
 622                 if (srrptr + 3 > srrspace) {
 623                         icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((opt->srr+2)<<24));
 624                         return -EINVAL;
 625                 }
 626                 memcpy(&nexthop, &optptr[srrptr-1], 4);
 627
 628                 rt = skb->rtable;
 629                 skb->rtable = NULL;
 630                 err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, skb->dev);
 631                 rt2 = skb->rtable;
 632                 if (err || (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) {
 633                         ip_rt_put(rt2);
 634                         skb->rtable = rt;
 635                         return -EINVAL;
 636                 }
 637                 ip_rt_put(rt);
 638                 if (rt2->rt_type != RTN_LOCAL)
 639                         break;
 640                 /* Superfast 8) loopback forward */
 641                 memcpy(&iph->daddr, &optptr[srrptr-1], 4);
 642                 opt->is_changed = 1;
 643         }
 644         if (srrptr <= srrspace) {
 645                 opt->srr_is_hit = 1;
 646                 opt->is_changed = 1;
 647         }
 648         return 0;
 649 }