bsd/net/pf_osfp.c

   1 /*
   2  * Copyright (c) 2007-2011 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 /*      $apfw: pf_osfp.c,v 1.4 2008/08/27 00:01:32 jhw Exp $ */
  30 /*      $OpenBSD: pf_osfp.c,v 1.12 2006/12/13 18:14:10 itojun Exp $ */
  31
  32 /*
  33  * Copyright (c) 2003 Mike Frantzen <frantzen@w4g.org>
  34  *
  35  * Permission to use, copy, modify, and distribute this software for any
  36  * purpose with or without fee is hereby granted, provided that the above
  37  * copyright notice and this permission notice appear in all copies.
  38  *
  39  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  40  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  41  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  42  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  43  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  44  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  45  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  46  *
  47  */
  48
  49 #include <machine/endian.h>
  50 #include <sys/param.h>
  51 #include <sys/socket.h>
  52 #include <sys/systm.h>
  53 #include <sys/mbuf.h>
  54
  55 #include <netinet/in.h>
  56 #include <netinet/in_systm.h>
  57 #include <netinet/ip.h>
  58 #include <netinet/tcp.h>
  59 #include <netinet/tcp_fsm.h>
  60
  61 #include <net/if.h>
  62 #include <net/pfvar.h>
  63
  64 #if INET6
  65 #include <netinet/ip6.h>
  66 #include <netinet6/in6_var.h>
  67 #endif /* INET6 */
  68
  69 #define DPFPRINTF(format, x...)                 \
  70         if (pf_status.debug >= PF_DEBUG_NOISY)  \
  71                 printf(format, ##x)
  72
  73 static SLIST_HEAD(pf_osfp_list, pf_os_fingerprint) pf_osfp_list;
  74 static struct pool pf_osfp_entry_pl;
  75 static struct pool pf_osfp_pl;
  76
  77 static struct pf_os_fingerprint *pf_osfp_find(struct pf_osfp_list *,
  78     struct pf_os_fingerprint *, u_int8_t);
  79 static struct pf_os_fingerprint *pf_osfp_find_exact(struct pf_osfp_list *,
  80     struct pf_os_fingerprint *);
  81 static void pf_osfp_insert(struct pf_osfp_list *, struct pf_os_fingerprint *);
  82
  83
  84 /*
  85  * Passively fingerprint the OS of the host (IPv4 TCP SYN packets only)
  86  * Returns the list of possible OSes.
  87  */
  88 struct pf_osfp_enlist *
  89 pf_osfp_fingerprint(struct pf_pdesc *pd, pbuf_t *pbuf, int off,
  90     const struct tcphdr *tcp)
  91 {
  92         struct ip *ip;
  93         struct ip6_hdr *ip6;
  94         char hdr[60];
  95
  96         if ((pd->af != PF_INET && pd->af != PF_INET6) ||
  97             pd->proto != IPPROTO_TCP ||
  98             (tcp->th_off << 2) < (int)sizeof(*tcp)) {
  99                 return NULL;
 100         }
 101
 102         if (pd->af == PF_INET) {
 103                 ip = pbuf->pb_data;
 104                 ip6 = (struct ip6_hdr *)NULL;
 105         } else {
 106                 ip = (struct ip *)NULL;
 107                 ip6 = pbuf->pb_data;
 108         }
 109         if (!pf_pull_hdr(pbuf, off, hdr, tcp->th_off << 2, NULL, NULL,
 110                 pd->af)) {
 111                 return NULL;
 112         }
 113
 114         return pf_osfp_fingerprint_hdr(ip, ip6, (struct tcphdr *)(void *)hdr);
 115 }
 116
 117 struct pf_osfp_enlist *
 118 pf_osfp_fingerprint_hdr(const struct ip *ip, const struct ip6_hdr *ip6,
 119     const struct tcphdr *tcp)
 120 {
 121 #if !INET6
 122 #pragma unused(ip6)
 123 #endif /* !INET6 */
 124         struct pf_os_fingerprint fp, *fpresult;
 125         int cnt, optlen = 0;
 126         const u_int8_t *optp;
 127         char srcname[128];
 128
 129         if ((tcp->th_flags & (TH_SYN | TH_ACK)) != TH_SYN) {
 130                 return NULL;
 131         }
 132         if (ip) {
 133                 if ((ip->ip_off & htons(IP_OFFMASK)) != 0) {
 134                         return NULL;
 135                 }
 136         }
 137
 138         memset(&fp, 0, sizeof(fp));
 139
 140         if (ip) {
 141                 fp.fp_psize = ntohs(ip->ip_len);
 142                 fp.fp_ttl = ip->ip_ttl;
 143                 if (ip->ip_off & htons(IP_DF)) {
 144                         fp.fp_flags |= PF_OSFP_DF;
 145                 }
 146                 (void) inet_ntop(AF_INET, &ip->ip_src, srcname,
 147                     (socklen_t)sizeof(srcname));
 148         }
 149 #if INET6
 150         else if (ip6) {
 151                 /* jumbo payload? */
 152                 fp.fp_psize = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen);
 153                 fp.fp_ttl = ip6->ip6_hlim;
 154                 fp.fp_flags |= PF_OSFP_DF;
 155                 fp.fp_flags |= PF_OSFP_INET6;
 156                 (void) inet_ntop(AF_INET6, &ip6->ip6_src, srcname,
 157                     (socklen_t)sizeof(srcname));
 158         }
 159 #endif
 160         else {
 161                 return NULL;
 162         }
 163         fp.fp_wsize = ntohs(tcp->th_win);
 164
 165
 166         cnt = (tcp->th_off << 2) - sizeof(*tcp);
 167         optp = (const u_int8_t *)((const char *)tcp + sizeof(*tcp));
 168         for (; cnt > 0; cnt -= optlen, optp += optlen) {
 169                 if (*optp == TCPOPT_EOL) {
 170                         break;
 171                 }
 172
 173                 fp.fp_optcnt++;
 174                 if (*optp == TCPOPT_NOP) {
 175                         fp.fp_tcpopts = (fp.fp_tcpopts << PF_OSFP_TCPOPT_BITS) |
 176                             PF_OSFP_TCPOPT_NOP;
 177                         optlen = 1;
 178                 } else {
 179                         if (cnt < 2) {
 180                                 return NULL;
 181                         }
 182                         optlen = optp[1];
 183                         if (optlen > cnt || optlen < 2) {
 184                                 return NULL;
 185                         }
 186                         switch (*optp) {
 187                         case TCPOPT_MAXSEG:
 188                                 if (optlen >= TCPOLEN_MAXSEG) {
 189                                         memcpy(&fp.fp_mss, &optp[2],
 190                                             sizeof(fp.fp_mss));
 191                                 }
 192                                 fp.fp_tcpopts = (fp.fp_tcpopts <<
 193                                         PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_MSS;
 194 #if BYTE_ORDER != BIG_ENDIAN
 195                                 NTOHS(fp.fp_mss);
 196 #endif
 197                                 break;
 198                         case TCPOPT_WINDOW:
 199                                 if (optlen >= TCPOLEN_WINDOW) {
 200                                         memcpy(&fp.fp_wscale, &optp[2],
 201                                             sizeof(fp.fp_wscale));
 202                                 }
 203 #if BYTE_ORDER != BIG_ENDIAN
 204                                 NTOHS(fp.fp_wscale);
 205 #endif
 206                                 fp.fp_tcpopts = (fp.fp_tcpopts <<
 207                                         PF_OSFP_TCPOPT_BITS) |
 208                                     PF_OSFP_TCPOPT_WSCALE;
 209                                 break;
 210                         case TCPOPT_SACK_PERMITTED:
 211                                 fp.fp_tcpopts = (fp.fp_tcpopts <<
 212                                         PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_SACK;
 213                                 break;
 214                         case TCPOPT_TIMESTAMP:
 215                                 if (optlen >= TCPOLEN_TIMESTAMP) {
 216                                         u_int32_t ts;
 217                                         memcpy(&ts, &optp[2], sizeof(ts));
 218                                         if (ts == 0) {
 219                                                 fp.fp_flags |= PF_OSFP_TS0;
 220                                         }
 221                                 }
 222                                 fp.fp_tcpopts = (fp.fp_tcpopts <<
 223                                         PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_TS;
 224                                 break;
 225                         default:
 226                                 return NULL;
 227                         }
 228                 }
 229                 optlen = MAX(optlen, 1);        /* paranoia */
 230         }
 231
 232         DPFPRINTF("fingerprinted %s:%d  %d:%d:%d:%d:%llx (%d) "
 233             "(TS=%s,M=%s%d,W=%s%d)\n",
 234             srcname, ntohs(tcp->th_sport),
 235             fp.fp_wsize, fp.fp_ttl, (fp.fp_flags & PF_OSFP_DF) != 0,
 236             fp.fp_psize, (long long int)fp.fp_tcpopts, fp.fp_optcnt,
 237             (fp.fp_flags & PF_OSFP_TS0) ? "0" : "",
 238             (fp.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
 239             (fp.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
 240             fp.fp_mss,
 241             (fp.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
 242             (fp.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
 243             fp.fp_wscale);
 244
 245         if ((fpresult = pf_osfp_find(&pf_osfp_list, &fp,
 246             PF_OSFP_MAXTTL_OFFSET))) {
 247                 return &fpresult->fp_oses;
 248         }
 249         return NULL;
 250 }
 251
 252 /* Match a fingerprint ID against a list of OSes */
 253 int
 254 pf_osfp_match(struct pf_osfp_enlist *list, pf_osfp_t os)
 255 {
 256         struct pf_osfp_entry *entry;
 257         int os_class, os_version, os_subtype;
 258         int en_class, en_version, en_subtype;
 259
 260         if (os == PF_OSFP_ANY) {
 261                 return 1;
 262         }
 263         if (list == NULL) {
 264                 DPFPRINTF("osfp no match against %x\n", os);
 265                 return os == PF_OSFP_UNKNOWN;
 266         }
 267         PF_OSFP_UNPACK(os, os_class, os_version, os_subtype);
 268         SLIST_FOREACH(entry, list, fp_entry) {
 269                 PF_OSFP_UNPACK(entry->fp_os, en_class, en_version, en_subtype);
 270                 if ((os_class == PF_OSFP_ANY || en_class == os_class) &&
 271                     (os_version == PF_OSFP_ANY || en_version == os_version) &&
 272                     (os_subtype == PF_OSFP_ANY || en_subtype == os_subtype)) {
 273                         DPFPRINTF("osfp matched %s %s %s  %x==%x\n",
 274                             entry->fp_class_nm, entry->fp_version_nm,
 275                             entry->fp_subtype_nm, os, entry->fp_os);
 276                         return 1;
 277                 }
 278         }
 279         DPFPRINTF("fingerprint 0x%x didn't match\n", os);
 280         return 0;
 281 }
 282
 283 /* Initialize the OS fingerprint system */
 284 void
 285 pf_osfp_initialize(void)
 286 {
 287         pool_init(&pf_osfp_entry_pl, sizeof(struct pf_osfp_entry), 0, 0, 0,
 288             "pfosfpen", NULL);
 289         pool_init(&pf_osfp_pl, sizeof(struct pf_os_fingerprint), 0, 0, 0,
 290             "pfosfp", NULL);
 291         SLIST_INIT(&pf_osfp_list);
 292 }
 293
 294 #if 0
 295 void
 296 pf_osfp_destroy(void)
 297 {
 298         pf_osfp_flush();
 299
 300         pool_destroy(&pf_osfp_pl);
 301         pool_destroy(&pf_osfp_entry_pl);
 302 }
 303 #endif
 304
 305 /* Flush the fingerprint list */
 306 void
 307 pf_osfp_flush(void)
 308 {
 309         struct pf_os_fingerprint *fp;
 310         struct pf_osfp_entry *entry;
 311
 312         while ((fp = SLIST_FIRST(&pf_osfp_list))) {
 313                 SLIST_REMOVE_HEAD(&pf_osfp_list, fp_next);
 314                 while ((entry = SLIST_FIRST(&fp->fp_oses))) {
 315                         SLIST_REMOVE_HEAD(&fp->fp_oses, fp_entry);
 316                         pool_put(&pf_osfp_entry_pl, entry);
 317                 }
 318                 pool_put(&pf_osfp_pl, fp);
 319         }
 320 }
 321
 322
 323 /* Add a fingerprint */
 324 int
 325 pf_osfp_add(struct pf_osfp_ioctl *fpioc)
 326 {
 327         struct pf_os_fingerprint *fp, fpadd;
 328         struct pf_osfp_entry *entry, *uentry;
 329
 330         memset(&fpadd, 0, sizeof(fpadd));
 331         fpadd.fp_tcpopts = fpioc->fp_tcpopts;
 332         fpadd.fp_wsize = fpioc->fp_wsize;
 333         fpadd.fp_psize = fpioc->fp_psize;
 334         fpadd.fp_mss = fpioc->fp_mss;
 335         fpadd.fp_flags = fpioc->fp_flags;
 336         fpadd.fp_optcnt = fpioc->fp_optcnt;
 337         fpadd.fp_wscale = fpioc->fp_wscale;
 338         fpadd.fp_ttl = fpioc->fp_ttl;
 339
 340         uentry = &fpioc->fp_os;
 341         uentry->fp_entry.sle_next = NULL;
 342         uentry->fp_class_nm[sizeof(uentry->fp_class_nm) - 1] = '\0';
 343         uentry->fp_version_nm[sizeof(uentry->fp_version_nm) - 1] = '\0';
 344         uentry->fp_subtype_nm[sizeof(uentry->fp_subtype_nm) - 1] = '\0';
 345
 346         DPFPRINTF("adding osfp %s %s %s = %s%d:%d:%d:%s%d:0x%llx %d "
 347             "(TS=%s,M=%s%d,W=%s%d) %x\n",
 348             fpioc->fp_os.fp_class_nm, fpioc->fp_os.fp_version_nm,
 349             fpioc->fp_os.fp_subtype_nm,
 350             (fpadd.fp_flags & PF_OSFP_WSIZE_MOD) ? "%" :
 351             (fpadd.fp_flags & PF_OSFP_WSIZE_MSS) ? "S" :
 352             (fpadd.fp_flags & PF_OSFP_WSIZE_MTU) ? "T" :
 353             (fpadd.fp_flags & PF_OSFP_WSIZE_DC) ? "*" : "",
 354             fpadd.fp_wsize,
 355             fpadd.fp_ttl,
 356             (fpadd.fp_flags & PF_OSFP_DF) ? 1 : 0,
 357             (fpadd.fp_flags & PF_OSFP_PSIZE_MOD) ? "%" :
 358             (fpadd.fp_flags & PF_OSFP_PSIZE_DC) ? "*" : "",
 359             fpadd.fp_psize,
 360             (long long int)fpadd.fp_tcpopts, fpadd.fp_optcnt,
 361             (fpadd.fp_flags & PF_OSFP_TS0) ? "0" : "",
 362             (fpadd.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
 363             (fpadd.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
 364             fpadd.fp_mss,
 365             (fpadd.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
 366             (fpadd.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
 367             fpadd.fp_wscale,
 368             fpioc->fp_os.fp_os);
 369
 370
 371         if ((fp = pf_osfp_find_exact(&pf_osfp_list, &fpadd))) {
 372                 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
 373                         if (PF_OSFP_ENTRY_EQ(entry, &fpioc->fp_os)) {
 374                                 return EEXIST;
 375                         }
 376                 }
 377                 if ((entry = pool_get(&pf_osfp_entry_pl, PR_WAITOK)) == NULL) {
 378                         return ENOMEM;
 379                 }
 380         } else {
 381                 if ((fp = pool_get(&pf_osfp_pl, PR_WAITOK)) == NULL) {
 382                         return ENOMEM;
 383                 }
 384                 memset(fp, 0, sizeof(*fp));
 385                 fp->fp_tcpopts = fpioc->fp_tcpopts;
 386                 fp->fp_wsize = fpioc->fp_wsize;
 387                 fp->fp_psize = fpioc->fp_psize;
 388                 fp->fp_mss = fpioc->fp_mss;
 389                 fp->fp_flags = fpioc->fp_flags;
 390                 fp->fp_optcnt = fpioc->fp_optcnt;
 391                 fp->fp_wscale = fpioc->fp_wscale;
 392                 fp->fp_ttl = fpioc->fp_ttl;
 393                 SLIST_INIT(&fp->fp_oses);
 394                 if ((entry = pool_get(&pf_osfp_entry_pl, PR_WAITOK)) == NULL) {
 395                         pool_put(&pf_osfp_pl, fp);
 396                         return ENOMEM;
 397                 }
 398                 pf_osfp_insert(&pf_osfp_list, fp);
 399         }
 400         memcpy(entry, &fpioc->fp_os, sizeof(*entry));
 401
 402         /* Make sure the strings are NUL terminated */
 403         entry->fp_class_nm[sizeof(entry->fp_class_nm) - 1] = '\0';
 404         entry->fp_version_nm[sizeof(entry->fp_version_nm) - 1] = '\0';
 405         entry->fp_subtype_nm[sizeof(entry->fp_subtype_nm) - 1] = '\0';
 406
 407         SLIST_INSERT_HEAD(&fp->fp_oses, entry, fp_entry);
 408
 409 #ifdef PFDEBUG
 410         if ((fp = pf_osfp_validate())) {
 411                 printf("Invalid fingerprint list\n");
 412         }
 413 #endif /* PFDEBUG */
 414         return 0;
 415 }
 416
 417
 418 /* Find a fingerprint in the list */
 419 struct pf_os_fingerprint *
 420 pf_osfp_find(struct pf_osfp_list *list, struct pf_os_fingerprint *find,
 421     u_int8_t ttldiff)
 422 {
 423         struct pf_os_fingerprint *f;
 424
 425 #define MATCH_INT(_MOD, _DC, _field)                                    \
 426         if ((f->fp_flags & _DC) == 0) {                                 \
 427                 if ((f->fp_flags & _MOD) == 0) {                        \
 428                         if (f->_field != find->_field)                  \
 429                                 continue;                               \
 430                 } else {                                                \
 431                         if (f->_field == 0 || find->_field % f->_field) \
 432                                 continue;                               \
 433                 }                                                       \
 434         }
 435
 436         SLIST_FOREACH(f, list, fp_next) {
 437                 if (f->fp_tcpopts != find->fp_tcpopts ||
 438                     f->fp_optcnt != find->fp_optcnt ||
 439                     f->fp_ttl < find->fp_ttl ||
 440                     f->fp_ttl - find->fp_ttl > ttldiff ||
 441                     (f->fp_flags & (PF_OSFP_DF | PF_OSFP_TS0)) !=
 442                     (find->fp_flags & (PF_OSFP_DF | PF_OSFP_TS0))) {
 443                         continue;
 444                 }
 445
 446                 MATCH_INT(PF_OSFP_PSIZE_MOD, PF_OSFP_PSIZE_DC, fp_psize)
 447                 MATCH_INT(PF_OSFP_MSS_MOD, PF_OSFP_MSS_DC, fp_mss)
 448                 MATCH_INT(PF_OSFP_WSCALE_MOD, PF_OSFP_WSCALE_DC, fp_wscale)
 449                 if ((f->fp_flags & PF_OSFP_WSIZE_DC) == 0) {
 450                         if (f->fp_flags & PF_OSFP_WSIZE_MSS) {
 451                                 if (find->fp_mss == 0) {
 452                                         continue;
 453                                 }
 454
 455 /*
 456  * Some "smart" NAT devices and DSL routers will tweak the MSS size and
 457  * will set it to whatever is suitable for the link type.
 458  */
 459 #define SMART_MSS       1460
 460                                 if ((find->fp_wsize % find->fp_mss ||
 461                                     find->fp_wsize / find->fp_mss !=
 462                                     f->fp_wsize) &&
 463                                     (find->fp_wsize % SMART_MSS ||
 464                                     find->fp_wsize / SMART_MSS !=
 465                                     f->fp_wsize)) {
 466                                         continue;
 467                                 }
 468                         } else if (f->fp_flags & PF_OSFP_WSIZE_MTU) {
 469                                 if (find->fp_mss == 0) {
 470                                         continue;
 471                                 }
 472
 473 #define MTUOFF  (sizeof (struct ip) + sizeof (struct tcphdr))
 474 #define SMART_MTU       (SMART_MSS + MTUOFF)
 475                                 if ((find->fp_wsize % (find->fp_mss + MTUOFF) ||
 476                                     find->fp_wsize / (find->fp_mss + MTUOFF) !=
 477                                     f->fp_wsize) &&
 478                                     (find->fp_wsize % SMART_MTU ||
 479                                     find->fp_wsize / SMART_MTU !=
 480                                     f->fp_wsize)) {
 481                                         continue;
 482                                 }
 483                         } else if (f->fp_flags & PF_OSFP_WSIZE_MOD) {
 484                                 if (f->fp_wsize == 0 || find->fp_wsize %
 485                                     f->fp_wsize) {
 486                                         continue;
 487                                 }
 488                         } else {
 489                                 if (f->fp_wsize != find->fp_wsize) {
 490                                         continue;
 491                                 }
 492                         }
 493                 }
 494                 return f;
 495         }
 496
 497         return NULL;
 498 }
 499
 500 /* Find an exact fingerprint in the list */
 501 struct pf_os_fingerprint *
 502 pf_osfp_find_exact(struct pf_osfp_list *list, struct pf_os_fingerprint *find)
 503 {
 504         struct pf_os_fingerprint *f;
 505
 506         SLIST_FOREACH(f, list, fp_next) {
 507                 if (f->fp_tcpopts == find->fp_tcpopts &&
 508                     f->fp_wsize == find->fp_wsize &&
 509                     f->fp_psize == find->fp_psize &&
 510                     f->fp_mss == find->fp_mss &&
 511                     f->fp_flags == find->fp_flags &&
 512                     f->fp_optcnt == find->fp_optcnt &&
 513                     f->fp_wscale == find->fp_wscale &&
 514                     f->fp_ttl == find->fp_ttl) {
 515                         return f;
 516                 }
 517         }
 518
 519         return NULL;
 520 }
 521
 522 /* Insert a fingerprint into the list */
 523 void
 524 pf_osfp_insert(struct pf_osfp_list *list, struct pf_os_fingerprint *ins)
 525 {
 526         struct pf_os_fingerprint *f, *prev = NULL;
 527
 528         /* XXX need to go semi tree based.  can key on tcp options */
 529
 530         SLIST_FOREACH(f, list, fp_next)
 531         prev = f;
 532         if (prev) {
 533                 SLIST_INSERT_AFTER(prev, ins, fp_next);
 534         } else {
 535                 SLIST_INSERT_HEAD(list, ins, fp_next);
 536         }
 537 }
 538
 539 /* Fill a fingerprint by its number (from an ioctl) */
 540 int
 541 pf_osfp_get(struct pf_osfp_ioctl *fpioc)
 542 {
 543         struct pf_os_fingerprint *fp;
 544         struct pf_osfp_entry *entry;
 545         int num = fpioc->fp_getnum;
 546         int i = 0;
 547
 548
 549         memset(fpioc, 0, sizeof(*fpioc));
 550         SLIST_FOREACH(fp, &pf_osfp_list, fp_next) {
 551                 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
 552                         if (i++ == num) {
 553                                 fpioc->fp_mss = fp->fp_mss;
 554                                 fpioc->fp_wsize = fp->fp_wsize;
 555                                 fpioc->fp_flags = fp->fp_flags;
 556                                 fpioc->fp_psize = fp->fp_psize;
 557                                 fpioc->fp_ttl = fp->fp_ttl;
 558                                 fpioc->fp_wscale = fp->fp_wscale;
 559                                 fpioc->fp_getnum = num;
 560                                 memcpy(&fpioc->fp_os, entry,
 561                                     sizeof(fpioc->fp_os));
 562                                 fpioc->fp_os.fp_entry.sle_next = NULL;
 563                                 return 0;
 564                         }
 565                 }
 566         }
 567
 568         return EBUSY;
 569 }
 570
 571
 572 /* Validate that each signature is reachable */
 573 struct pf_os_fingerprint *
 574 pf_osfp_validate(void)
 575 {
 576         struct pf_os_fingerprint *f, *f2, find;
 577
 578         SLIST_FOREACH(f, &pf_osfp_list, fp_next) {
 579                 memcpy(&find, f, sizeof(find));
 580
 581                 /* We do a few MSS/th_win percolations to make things unique */
 582                 if (find.fp_mss == 0) {
 583                         find.fp_mss = 128;
 584                 }
 585                 if (f->fp_flags & PF_OSFP_WSIZE_MSS) {
 586                         find.fp_wsize *= find.fp_mss;
 587                 } else if (f->fp_flags & PF_OSFP_WSIZE_MTU) {
 588                         find.fp_wsize *= (find.fp_mss + 40);
 589                 } else if (f->fp_flags & PF_OSFP_WSIZE_MOD) {
 590                         find.fp_wsize *= 2;
 591                 }
 592                 if (f != (f2 = pf_osfp_find(&pf_osfp_list, &find, 0))) {
 593                         if (f2) {
 594                                 printf("Found \"%s %s %s\" instead of "
 595                                     "\"%s %s %s\"\n",
 596                                     SLIST_FIRST(&f2->fp_oses)->fp_class_nm,
 597                                     SLIST_FIRST(&f2->fp_oses)->fp_version_nm,
 598                                     SLIST_FIRST(&f2->fp_oses)->fp_subtype_nm,
 599                                     SLIST_FIRST(&f->fp_oses)->fp_class_nm,
 600                                     SLIST_FIRST(&f->fp_oses)->fp_version_nm,
 601                                     SLIST_FIRST(&f->fp_oses)->fp_subtype_nm);
 602                         } else {
 603                                 printf("Couldn't find \"%s %s %s\"\n",
 604                                     SLIST_FIRST(&f->fp_oses)->fp_class_nm,
 605                                     SLIST_FIRST(&f->fp_oses)->fp_version_nm,
 606                                     SLIST_FIRST(&f->fp_oses)->fp_subtype_nm);
 607                         }
 608                         return f;
 609                 }
 610         }
 611         return NULL;
 612 }