sys/netpfil/pf/pf_osfp.c

   1 /*-
   2  * Copyright (c) 2003 Mike Frantzen <frantzen@w4g.org>
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15  *
  16  *      $OpenBSD: pf_osfp.c,v 1.14 2008/06/12 18:17:01 henning Exp $
  17  */
  18
  19 #include <sys/cdefs.h>
  20 __FBSDID("$FreeBSD$");
  21
  22 #include <sys/param.h>
  23 #include <sys/kernel.h>
  24 #include <sys/socket.h>
  25
  26 #include <netinet/in.h>
  27 #include <netinet/ip.h>
  28 #include <netinet/tcp.h>
  29
  30 #include <net/if.h>
  31 #include <net/pfvar.h>
  32
  33 #include <netinet/ip6.h>
  34 #include <netinet6/in6_var.h>
  35
  36 static MALLOC_DEFINE(M_PFOSFP, "pf_osfp", "pf(4) operating system fingerprints");
  37 #define DPFPRINTF(format, x...)         \
  38         if (V_pf_status.debug >= PF_DEBUG_NOISY)        \
  39                 printf(format , ##x)
  40
  41 SLIST_HEAD(pf_osfp_list, pf_os_fingerprint);
  42 static VNET_DEFINE(struct pf_osfp_list, pf_osfp_list) =
  43         SLIST_HEAD_INITIALIZER();
  44 #define V_pf_osfp_list                  VNET(pf_osfp_list)
  45
  46 static struct pf_osfp_enlist    *pf_osfp_fingerprint_hdr(const struct ip *,
  47                                     const struct ip6_hdr *,
  48                                     const struct tcphdr *);
  49 static struct pf_os_fingerprint *pf_osfp_find(struct pf_osfp_list *,
  50                                     struct pf_os_fingerprint *, u_int8_t);
  51 static struct pf_os_fingerprint *pf_osfp_find_exact(struct pf_osfp_list *,
  52                                     struct pf_os_fingerprint *);
  53 static void                      pf_osfp_insert(struct pf_osfp_list *,
  54                                     struct pf_os_fingerprint *);
  55 #ifdef PFDEBUG
  56 static struct pf_os_fingerprint *pf_osfp_validate(void);
  57 #endif
  58
  59 /*
  60  * Passively fingerprint the OS of the host (IPv4 TCP SYN packets only)
  61  * Returns the list of possible OSes.
  62  */
  63 struct pf_osfp_enlist *
  64 pf_osfp_fingerprint(struct pf_pdesc *pd, struct mbuf *m, int off,
  65     const struct tcphdr *tcp)
  66 {
  67         struct ip *ip;
  68         struct ip6_hdr *ip6;
  69         char hdr[60];
  70
  71         if ((pd->af != PF_INET && pd->af != PF_INET6) ||
  72             pd->proto != IPPROTO_TCP || (tcp->th_off << 2) < sizeof(*tcp))
  73                 return (NULL);
  74
  75         if (pd->af == PF_INET) {
  76                 ip = mtod(m, struct ip *);
  77                 ip6 = (struct ip6_hdr *)NULL;
  78         } else {
  79                 ip = (struct ip *)NULL;
  80                 ip6 = mtod(m, struct ip6_hdr *);
  81         }
  82         if (!pf_pull_hdr(m, off, hdr, tcp->th_off << 2, NULL, NULL,
  83             pd->af)) return (NULL);
  84
  85         return (pf_osfp_fingerprint_hdr(ip, ip6, (struct tcphdr *)hdr));
  86 }
  87
  88 static struct pf_osfp_enlist *
  89 pf_osfp_fingerprint_hdr(const struct ip *ip, const struct ip6_hdr *ip6, const struct tcphdr *tcp)
  90 {
  91         struct pf_os_fingerprint fp, *fpresult;
  92         int cnt, optlen = 0;
  93         const u_int8_t *optp;
  94         char srcname[128];
  95
  96         if ((tcp->th_flags & (TH_SYN|TH_ACK)) != TH_SYN)
  97                 return (NULL);
  98         if (ip) {
  99                 if ((ip->ip_off & htons(IP_OFFMASK)) != 0)
 100                         return (NULL);
 101         }
 102
 103         memset(&fp, 0, sizeof(fp));
 104
 105         if (ip) {
 106                 fp.fp_psize = ntohs(ip->ip_len);
 107                 fp.fp_ttl = ip->ip_ttl;
 108                 if (ip->ip_off & htons(IP_DF))
 109                         fp.fp_flags |= PF_OSFP_DF;
 110                 strlcpy(srcname, inet_ntoa(ip->ip_src), sizeof(srcname));
 111         }
 112 #ifdef INET6
 113         else if (ip6) {
 114                 /* jumbo payload? */
 115                 fp.fp_psize = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen);
 116                 fp.fp_ttl = ip6->ip6_hlim;
 117                 fp.fp_flags |= PF_OSFP_DF;
 118                 fp.fp_flags |= PF_OSFP_INET6;
 119                 strlcpy(srcname, ip6_sprintf((struct in6_addr *)&ip6->ip6_src),
 120                     sizeof(srcname));
 121         }
 122 #endif
 123         else
 124                 return (NULL);
 125         fp.fp_wsize = ntohs(tcp->th_win);
 126
 127
 128         cnt = (tcp->th_off << 2) - sizeof(*tcp);
 129         optp = (const u_int8_t *)((const char *)tcp + sizeof(*tcp));
 130         for (; cnt > 0; cnt -= optlen, optp += optlen) {
 131                 if (*optp == TCPOPT_EOL)
 132                         break;
 133
 134                 fp.fp_optcnt++;
 135                 if (*optp == TCPOPT_NOP) {
 136                         fp.fp_tcpopts = (fp.fp_tcpopts << PF_OSFP_TCPOPT_BITS) |
 137                             PF_OSFP_TCPOPT_NOP;
 138                         optlen = 1;
 139                 } else {
 140                         if (cnt < 2)
 141                                 return (NULL);
 142                         optlen = optp[1];
 143                         if (optlen > cnt || optlen < 2)
 144                                 return (NULL);
 145                         switch (*optp) {
 146                         case TCPOPT_MAXSEG:
 147                                 if (optlen >= TCPOLEN_MAXSEG)
 148                                         memcpy(&fp.fp_mss, &optp[2],
 149                                             sizeof(fp.fp_mss));
 150                                 fp.fp_tcpopts = (fp.fp_tcpopts <<
 151                                     PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_MSS;
 152                                 NTOHS(fp.fp_mss);
 153                                 break;
 154                         case TCPOPT_WINDOW:
 155                                 if (optlen >= TCPOLEN_WINDOW)
 156                                         memcpy(&fp.fp_wscale, &optp[2],
 157                                             sizeof(fp.fp_wscale));
 158                                 NTOHS(fp.fp_wscale);
 159                                 fp.fp_tcpopts = (fp.fp_tcpopts <<
 160                                     PF_OSFP_TCPOPT_BITS) |
 161                                     PF_OSFP_TCPOPT_WSCALE;
 162                                 break;
 163                         case TCPOPT_SACK_PERMITTED:
 164                                 fp.fp_tcpopts = (fp.fp_tcpopts <<
 165                                     PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_SACK;
 166                                 break;
 167                         case TCPOPT_TIMESTAMP:
 168                                 if (optlen >= TCPOLEN_TIMESTAMP) {
 169                                         u_int32_t ts;
 170                                         memcpy(&ts, &optp[2], sizeof(ts));
 171                                         if (ts == 0)
 172                                                 fp.fp_flags |= PF_OSFP_TS0;
 173
 174                                 }
 175                                 fp.fp_tcpopts = (fp.fp_tcpopts <<
 176                                     PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_TS;
 177                                 break;
 178                         default:
 179                                 return (NULL);
 180                         }
 181                 }
 182                 optlen = MAX(optlen, 1);        /* paranoia */
 183         }
 184
 185         DPFPRINTF("fingerprinted %s:%d  %d:%d:%d:%d:%llx (%d) "
 186             "(TS=%s,M=%s%d,W=%s%d)\n",
 187             srcname, ntohs(tcp->th_sport),
 188             fp.fp_wsize, fp.fp_ttl, (fp.fp_flags & PF_OSFP_DF) != 0,
 189             fp.fp_psize, (long long int)fp.fp_tcpopts, fp.fp_optcnt,
 190             (fp.fp_flags & PF_OSFP_TS0) ? "0" : "",
 191             (fp.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
 192             (fp.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
 193             fp.fp_mss,
 194             (fp.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
 195             (fp.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
 196             fp.fp_wscale);
 197
 198         if ((fpresult = pf_osfp_find(&V_pf_osfp_list, &fp,
 199             PF_OSFP_MAXTTL_OFFSET)))
 200                 return (&fpresult->fp_oses);
 201         return (NULL);
 202 }
 203
 204 /* Match a fingerprint ID against a list of OSes */
 205 int
 206 pf_osfp_match(struct pf_osfp_enlist *list, pf_osfp_t os)
 207 {
 208         struct pf_osfp_entry *entry;
 209         int os_class, os_version, os_subtype;
 210         int en_class, en_version, en_subtype;
 211
 212         if (os == PF_OSFP_ANY)
 213                 return (1);
 214         if (list == NULL) {
 215                 DPFPRINTF("osfp no match against %x\n", os);
 216                 return (os == PF_OSFP_UNKNOWN);
 217         }
 218         PF_OSFP_UNPACK(os, os_class, os_version, os_subtype);
 219         SLIST_FOREACH(entry, list, fp_entry) {
 220                 PF_OSFP_UNPACK(entry->fp_os, en_class, en_version, en_subtype);
 221                 if ((os_class == PF_OSFP_ANY || en_class == os_class) &&
 222                     (os_version == PF_OSFP_ANY || en_version == os_version) &&
 223                     (os_subtype == PF_OSFP_ANY || en_subtype == os_subtype)) {
 224                         DPFPRINTF("osfp matched %s %s %s  %x==%x\n",
 225                             entry->fp_class_nm, entry->fp_version_nm,
 226                             entry->fp_subtype_nm, os, entry->fp_os);
 227                         return (1);
 228                 }
 229         }
 230         DPFPRINTF("fingerprint 0x%x didn't match\n", os);
 231         return (0);
 232 }
 233
 234 /* Flush the fingerprint list */
 235 void
 236 pf_osfp_flush(void)
 237 {
 238         struct pf_os_fingerprint *fp;
 239         struct pf_osfp_entry *entry;
 240
 241         while ((fp = SLIST_FIRST(&V_pf_osfp_list))) {
 242                 SLIST_REMOVE_HEAD(&V_pf_osfp_list, fp_next);
 243                 while ((entry = SLIST_FIRST(&fp->fp_oses))) {
 244                         SLIST_REMOVE_HEAD(&fp->fp_oses, fp_entry);
 245                         free(entry, M_PFOSFP);
 246                 }
 247                 free(fp, M_PFOSFP);
 248         }
 249 }
 250
 251
 252 /* Add a fingerprint */
 253 int
 254 pf_osfp_add(struct pf_osfp_ioctl *fpioc)
 255 {
 256         struct pf_os_fingerprint *fp, fpadd;
 257         struct pf_osfp_entry *entry;
 258
 259         PF_RULES_WASSERT();
 260
 261         memset(&fpadd, 0, sizeof(fpadd));
 262         fpadd.fp_tcpopts = fpioc->fp_tcpopts;
 263         fpadd.fp_wsize = fpioc->fp_wsize;
 264         fpadd.fp_psize = fpioc->fp_psize;
 265         fpadd.fp_mss = fpioc->fp_mss;
 266         fpadd.fp_flags = fpioc->fp_flags;
 267         fpadd.fp_optcnt = fpioc->fp_optcnt;
 268         fpadd.fp_wscale = fpioc->fp_wscale;
 269         fpadd.fp_ttl = fpioc->fp_ttl;
 270
 271 #if 0   /* XXX RYAN wants to fix logging */
 272         DPFPRINTF("adding osfp %s %s %s = %s%d:%d:%d:%s%d:0x%llx %d "
 273             "(TS=%s,M=%s%d,W=%s%d) %x\n",
 274             fpioc->fp_os.fp_class_nm, fpioc->fp_os.fp_version_nm,
 275             fpioc->fp_os.fp_subtype_nm,
 276             (fpadd.fp_flags & PF_OSFP_WSIZE_MOD) ? "%" :
 277             (fpadd.fp_flags & PF_OSFP_WSIZE_MSS) ? "S" :
 278             (fpadd.fp_flags & PF_OSFP_WSIZE_MTU) ? "T" :
 279             (fpadd.fp_flags & PF_OSFP_WSIZE_DC) ? "*" : "",
 280             fpadd.fp_wsize,
 281             fpadd.fp_ttl,
 282             (fpadd.fp_flags & PF_OSFP_DF) ? 1 : 0,
 283             (fpadd.fp_flags & PF_OSFP_PSIZE_MOD) ? "%" :
 284             (fpadd.fp_flags & PF_OSFP_PSIZE_DC) ? "*" : "",
 285             fpadd.fp_psize,
 286             (long long int)fpadd.fp_tcpopts, fpadd.fp_optcnt,
 287             (fpadd.fp_flags & PF_OSFP_TS0) ? "0" : "",
 288             (fpadd.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
 289             (fpadd.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
 290             fpadd.fp_mss,
 291             (fpadd.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
 292             (fpadd.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
 293             fpadd.fp_wscale,
 294             fpioc->fp_os.fp_os);
 295 #endif
 296
 297         if ((fp = pf_osfp_find_exact(&V_pf_osfp_list, &fpadd))) {
 298                  SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
 299                         if (PF_OSFP_ENTRY_EQ(entry, &fpioc->fp_os))
 300                                 return (EEXIST);
 301                 }
 302                 if ((entry = malloc(sizeof(*entry), M_PFOSFP, M_NOWAIT))
 303                     == NULL)
 304                         return (ENOMEM);
 305         } else {
 306                 if ((fp = malloc(sizeof(*fp), M_PFOSFP, M_ZERO | M_NOWAIT))
 307                     == NULL)
 308                         return (ENOMEM);
 309                 fp->fp_tcpopts = fpioc->fp_tcpopts;
 310                 fp->fp_wsize = fpioc->fp_wsize;
 311                 fp->fp_psize = fpioc->fp_psize;
 312                 fp->fp_mss = fpioc->fp_mss;
 313                 fp->fp_flags = fpioc->fp_flags;
 314                 fp->fp_optcnt = fpioc->fp_optcnt;
 315                 fp->fp_wscale = fpioc->fp_wscale;
 316                 fp->fp_ttl = fpioc->fp_ttl;
 317                 SLIST_INIT(&fp->fp_oses);
 318                 if ((entry = malloc(sizeof(*entry), M_PFOSFP, M_NOWAIT))
 319                     == NULL) {
 320                         free(fp, M_PFOSFP);
 321                         return (ENOMEM);
 322                 }
 323                 pf_osfp_insert(&V_pf_osfp_list, fp);
 324         }
 325         memcpy(entry, &fpioc->fp_os, sizeof(*entry));
 326
 327         /* Make sure the strings are NUL terminated */
 328         entry->fp_class_nm[sizeof(entry->fp_class_nm)-1] = '\0';
 329         entry->fp_version_nm[sizeof(entry->fp_version_nm)-1] = '\0';
 330         entry->fp_subtype_nm[sizeof(entry->fp_subtype_nm)-1] = '\0';
 331
 332         SLIST_INSERT_HEAD(&fp->fp_oses, entry, fp_entry);
 333
 334 #ifdef PFDEBUG
 335         if ((fp = pf_osfp_validate()))
 336                 printf("Invalid fingerprint list\n");
 337 #endif /* PFDEBUG */
 338         return (0);
 339 }
 340
 341
 342 /* Find a fingerprint in the list */
 343 static struct pf_os_fingerprint *
 344 pf_osfp_find(struct pf_osfp_list *list, struct pf_os_fingerprint *find,
 345     u_int8_t ttldiff)
 346 {
 347         struct pf_os_fingerprint *f;
 348
 349 #define MATCH_INT(_MOD, _DC, _field)                                    \
 350         if ((f->fp_flags & _DC) == 0) {                                 \
 351                 if ((f->fp_flags & _MOD) == 0) {                        \
 352                         if (f->_field != find->_field)                  \
 353                                 continue;                               \
 354                 } else {                                                \
 355                         if (f->_field == 0 || find->_field % f->_field) \
 356                                 continue;                               \
 357                 }                                                       \
 358         }
 359
 360         SLIST_FOREACH(f, list, fp_next) {
 361                 if (f->fp_tcpopts != find->fp_tcpopts ||
 362                     f->fp_optcnt != find->fp_optcnt ||
 363                     f->fp_ttl < find->fp_ttl ||
 364                     f->fp_ttl - find->fp_ttl > ttldiff ||
 365                     (f->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)) !=
 366                     (find->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)))
 367                         continue;
 368
 369                 MATCH_INT(PF_OSFP_PSIZE_MOD, PF_OSFP_PSIZE_DC, fp_psize)
 370                 MATCH_INT(PF_OSFP_MSS_MOD, PF_OSFP_MSS_DC, fp_mss)
 371                 MATCH_INT(PF_OSFP_WSCALE_MOD, PF_OSFP_WSCALE_DC, fp_wscale)
 372                 if ((f->fp_flags & PF_OSFP_WSIZE_DC) == 0) {
 373                         if (f->fp_flags & PF_OSFP_WSIZE_MSS) {
 374                                 if (find->fp_mss == 0)
 375                                         continue;
 376
 377 /*
 378  * Some "smart" NAT devices and DSL routers will tweak the MSS size and
 379  * will set it to whatever is suitable for the link type.
 380  */
 381 #define SMART_MSS       1460
 382                                 if ((find->fp_wsize % find->fp_mss ||
 383                                     find->fp_wsize / find->fp_mss !=
 384                                     f->fp_wsize) &&
 385                                     (find->fp_wsize % SMART_MSS ||
 386                                     find->fp_wsize / SMART_MSS !=
 387                                     f->fp_wsize))
 388                                         continue;
 389                         } else if (f->fp_flags & PF_OSFP_WSIZE_MTU) {
 390                                 if (find->fp_mss == 0)
 391                                         continue;
 392
 393 #define MTUOFF          (sizeof(struct ip) + sizeof(struct tcphdr))
 394 #define SMART_MTU       (SMART_MSS + MTUOFF)
 395                                 if ((find->fp_wsize % (find->fp_mss + MTUOFF) ||
 396                                     find->fp_wsize / (find->fp_mss + MTUOFF) !=
 397                                     f->fp_wsize) &&
 398                                     (find->fp_wsize % SMART_MTU ||
 399                                     find->fp_wsize / SMART_MTU !=
 400                                     f->fp_wsize))
 401                                         continue;
 402                         } else if (f->fp_flags & PF_OSFP_WSIZE_MOD) {
 403                                 if (f->fp_wsize == 0 || find->fp_wsize %
 404                                     f->fp_wsize)
 405                                         continue;
 406                         } else {
 407                                 if (f->fp_wsize != find->fp_wsize)
 408                                         continue;
 409                         }
 410                 }
 411                 return (f);
 412         }
 413
 414         return (NULL);
 415 }
 416
 417 /* Find an exact fingerprint in the list */
 418 static struct pf_os_fingerprint *
 419 pf_osfp_find_exact(struct pf_osfp_list *list, struct pf_os_fingerprint *find)
 420 {
 421         struct pf_os_fingerprint *f;
 422
 423         SLIST_FOREACH(f, list, fp_next) {
 424                 if (f->fp_tcpopts == find->fp_tcpopts &&
 425                     f->fp_wsize == find->fp_wsize &&
 426                     f->fp_psize == find->fp_psize &&
 427                     f->fp_mss == find->fp_mss &&
 428                     f->fp_flags == find->fp_flags &&
 429                     f->fp_optcnt == find->fp_optcnt &&
 430                     f->fp_wscale == find->fp_wscale &&
 431                     f->fp_ttl == find->fp_ttl)
 432                         return (f);
 433         }
 434
 435         return (NULL);
 436 }
 437
 438 /* Insert a fingerprint into the list */
 439 static void
 440 pf_osfp_insert(struct pf_osfp_list *list, struct pf_os_fingerprint *ins)
 441 {
 442         struct pf_os_fingerprint *f, *prev = NULL;
 443
 444         /* XXX need to go semi tree based.  can key on tcp options */
 445
 446         SLIST_FOREACH(f, list, fp_next)
 447                 prev = f;
 448         if (prev)
 449                 SLIST_INSERT_AFTER(prev, ins, fp_next);
 450         else
 451                 SLIST_INSERT_HEAD(list, ins, fp_next);
 452 }
 453
 454 /* Fill a fingerprint by its number (from an ioctl) */
 455 int
 456 pf_osfp_get(struct pf_osfp_ioctl *fpioc)
 457 {
 458         struct pf_os_fingerprint *fp;
 459         struct pf_osfp_entry *entry;
 460         int num = fpioc->fp_getnum;
 461         int i = 0;
 462
 463
 464         memset(fpioc, 0, sizeof(*fpioc));
 465         SLIST_FOREACH(fp, &V_pf_osfp_list, fp_next) {
 466                 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
 467                         if (i++ == num) {
 468                                 fpioc->fp_mss = fp->fp_mss;
 469                                 fpioc->fp_wsize = fp->fp_wsize;
 470                                 fpioc->fp_flags = fp->fp_flags;
 471                                 fpioc->fp_psize = fp->fp_psize;
 472                                 fpioc->fp_ttl = fp->fp_ttl;
 473                                 fpioc->fp_wscale = fp->fp_wscale;
 474                                 fpioc->fp_getnum = num;
 475                                 memcpy(&fpioc->fp_os, entry,
 476                                     sizeof(fpioc->fp_os));
 477                                 return (0);
 478                         }
 479                 }
 480         }
 481
 482         return (EBUSY);
 483 }
 484
 485
 486 #ifdef PFDEBUG
 487 /* Validate that each signature is reachable */
 488 static struct pf_os_fingerprint *
 489 pf_osfp_validate(void)
 490 {
 491         struct pf_os_fingerprint *f, *f2, find;
 492
 493         SLIST_FOREACH(f, &V_pf_osfp_list, fp_next) {
 494                 memcpy(&find, f, sizeof(find));
 495
 496                 /* We do a few MSS/th_win percolations to make things unique */
 497                 if (find.fp_mss == 0)
 498                         find.fp_mss = 128;
 499                 if (f->fp_flags & PF_OSFP_WSIZE_MSS)
 500                         find.fp_wsize *= find.fp_mss;
 501                 else if (f->fp_flags & PF_OSFP_WSIZE_MTU)
 502                         find.fp_wsize *= (find.fp_mss + 40);
 503                 else if (f->fp_flags & PF_OSFP_WSIZE_MOD)
 504                         find.fp_wsize *= 2;
 505                 if (f != (f2 = pf_osfp_find(&V_pf_osfp_list, &find, 0))) {
 506                         if (f2)
 507                                 printf("Found \"%s %s %s\" instead of "
 508                                     "\"%s %s %s\"\n",
 509                                     SLIST_FIRST(&f2->fp_oses)->fp_class_nm,
 510                                     SLIST_FIRST(&f2->fp_oses)->fp_version_nm,
 511                                     SLIST_FIRST(&f2->fp_oses)->fp_subtype_nm,
 512                                     SLIST_FIRST(&f->fp_oses)->fp_class_nm,
 513                                     SLIST_FIRST(&f->fp_oses)->fp_version_nm,
 514                                     SLIST_FIRST(&f->fp_oses)->fp_subtype_nm);
 515                         else
 516                                 printf("Couldn't find \"%s %s %s\"\n",
 517                                     SLIST_FIRST(&f->fp_oses)->fp_class_nm,
 518                                     SLIST_FIRST(&f->fp_oses)->fp_version_nm,
 519                                     SLIST_FIRST(&f->fp_oses)->fp_subtype_nm);
 520                         return (f);
 521                 }
 522         }
 523         return (NULL);
 524 }
 525 #endif /* PFDEBUG */