sys/contrib/pf/net/pf_osfp.c

   1 /*      $OpenBSD: pf_osfp.c,v 1.12 2006/12/13 18:14:10 itojun Exp $ */
   2
   3 /*
   4  * Copyright (c) 2003 Mike Frantzen <frantzen@w4g.org>
   5  *
   6  * Permission to use, copy, modify, and distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  *
  18  */
  19
  20 #ifdef __FreeBSD__
  21 #include <sys/cdefs.h>
  22 __FBSDID("$FreeBSD$");
  23 #endif
  24
  25 #include <sys/param.h>
  26 #include <sys/socket.h>
  27 #ifdef _KERNEL
  28 # include <sys/systm.h>
  29 #endif /* _KERNEL */
  30 #include <sys/mbuf.h>
  31
  32 #include <netinet/in.h>
  33 #include <netinet/in_systm.h>
  34 #include <netinet/ip.h>
  35 #include <netinet/tcp.h>
  36
  37 #include <net/if.h>
  38 #include <net/pfvar.h>
  39
  40 #include <netinet/ip6.h>
  41 #ifdef _KERNEL
  42 #include <netinet6/in6_var.h>
  43 #endif
  44
  45 #ifdef _KERNEL
  46 # define DPFPRINTF(format, x...)                \
  47         if (pf_status.debug >= PF_DEBUG_NOISY)  \
  48                 printf(format , ##x)
  49 #ifdef __FreeBSD__
  50 typedef uma_zone_t pool_t;
  51 #else
  52 typedef struct pool pool_t;
  53 #endif
  54
  55 #else
  56 /* Userland equivalents so we can lend code to tcpdump et al. */
  57
  58 # include <arpa/inet.h>
  59 # include <errno.h>
  60 # include <stdio.h>
  61 # include <stdlib.h>
  62 # include <string.h>
  63 # include <netdb.h>
  64 # define pool_t                 int
  65 # define pool_get(pool, flags)  malloc(*(pool))
  66 # define pool_put(pool, item)   free(item)
  67 # define pool_init(pool, size, a, ao, f, m, p)  (*(pool)) = (size)
  68
  69 # ifdef __FreeBSD__
  70 # define NTOHS(x) (x) = ntohs((u_int16_t)(x))
  71 # endif
  72
  73 # ifdef PFDEBUG
  74 #  include <sys/stdarg.h>
  75 #  define DPFPRINTF(format, x...)       fprintf(stderr, format , ##x)
  76 # else
  77 #  define DPFPRINTF(format, x...)       ((void)0)
  78 # endif /* PFDEBUG */
  79 #endif /* _KERNEL */
  80
  81
  82 SLIST_HEAD(pf_osfp_list, pf_os_fingerprint) pf_osfp_list;
  83 pool_t pf_osfp_entry_pl;
  84 pool_t pf_osfp_pl;
  85
  86 struct pf_os_fingerprint        *pf_osfp_find(struct pf_osfp_list *,
  87                                     struct pf_os_fingerprint *, u_int8_t);
  88 struct pf_os_fingerprint        *pf_osfp_find_exact(struct pf_osfp_list *,
  89                                     struct pf_os_fingerprint *);
  90 void                             pf_osfp_insert(struct pf_osfp_list *,
  91                                     struct pf_os_fingerprint *);
  92
  93
  94 #ifdef _KERNEL
  95 /*
  96  * Passively fingerprint the OS of the host (IPv4 TCP SYN packets only)
  97  * Returns the list of possible OSes.
  98  */
  99 struct pf_osfp_enlist *
 100 pf_osfp_fingerprint(struct pf_pdesc *pd, struct mbuf *m, int off,
 101     const struct tcphdr *tcp)
 102 {
 103         struct ip *ip;
 104         struct ip6_hdr *ip6;
 105         char hdr[60];
 106
 107         if ((pd->af != PF_INET && pd->af != PF_INET6) ||
 108             pd->proto != IPPROTO_TCP || (tcp->th_off << 2) < sizeof(*tcp))
 109                 return (NULL);
 110
 111         if (pd->af == PF_INET) {
 112                 ip = mtod(m, struct ip *);
 113                 ip6 = (struct ip6_hdr *)NULL;
 114         } else {
 115                 ip = (struct ip *)NULL;
 116                 ip6 = mtod(m, struct ip6_hdr *);
 117         }
 118         if (!pf_pull_hdr(m, off, hdr, tcp->th_off << 2, NULL, NULL,
 119             pd->af)) return (NULL);
 120
 121         return (pf_osfp_fingerprint_hdr(ip, ip6, (struct tcphdr *)hdr));
 122 }
 123 #endif /* _KERNEL */
 124
 125 struct pf_osfp_enlist *
 126 pf_osfp_fingerprint_hdr(const struct ip *ip, const struct ip6_hdr *ip6, const struct tcphdr *tcp)
 127 {
 128         struct pf_os_fingerprint fp, *fpresult;
 129         int cnt, optlen = 0;
 130         const u_int8_t *optp;
 131 #ifdef _KERNEL
 132         char srcname[128];
 133 #else
 134         char srcname[NI_MAXHOST];
 135 #endif
 136
 137         if ((tcp->th_flags & (TH_SYN|TH_ACK)) != TH_SYN)
 138                 return (NULL);
 139         if (ip) {
 140                 if ((ip->ip_off & htons(IP_OFFMASK)) != 0)
 141                         return (NULL);
 142         }
 143
 144         memset(&fp, 0, sizeof(fp));
 145
 146         if (ip) {
 147 #ifndef _KERNEL
 148                 struct sockaddr_in sin;
 149 #endif
 150
 151                 fp.fp_psize = ntohs(ip->ip_len);
 152                 fp.fp_ttl = ip->ip_ttl;
 153                 if (ip->ip_off & htons(IP_DF))
 154                         fp.fp_flags |= PF_OSFP_DF;
 155 #ifdef _KERNEL
 156                 strlcpy(srcname, inet_ntoa(ip->ip_src), sizeof(srcname));
 157 #else
 158                 memset(&sin, 0, sizeof(sin));
 159                 sin.sin_family = AF_INET;
 160                 sin.sin_len = sizeof(struct sockaddr_in);
 161                 sin.sin_addr = ip->ip_src;
 162                 (void)getnameinfo((struct sockaddr *)&sin,
 163                     sizeof(struct sockaddr_in), srcname, sizeof(srcname),
 164                     NULL, 0, NI_NUMERICHOST);
 165 #endif
 166         }
 167 #ifdef INET6
 168         else if (ip6) {
 169 #ifndef _KERNEL
 170                 struct sockaddr_in6 sin6;
 171 #endif
 172
 173                 /* jumbo payload? */
 174                 fp.fp_psize = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen);
 175                 fp.fp_ttl = ip6->ip6_hlim;
 176                 fp.fp_flags |= PF_OSFP_DF;
 177                 fp.fp_flags |= PF_OSFP_INET6;
 178 #ifdef _KERNEL
 179                 strlcpy(srcname, ip6_sprintf((struct in6_addr *)&ip6->ip6_src),
 180                     sizeof(srcname));
 181 #else
 182                 memset(&sin6, 0, sizeof(sin6));
 183                 sin6.sin6_family = AF_INET6;
 184                 sin6.sin6_len = sizeof(struct sockaddr_in6);
 185                 sin6.sin6_addr = ip6->ip6_src;
 186                 (void)getnameinfo((struct sockaddr *)&sin6,
 187                     sizeof(struct sockaddr_in6), srcname, sizeof(srcname),
 188                     NULL, 0, NI_NUMERICHOST);
 189 #endif
 190         }
 191 #endif
 192         else
 193                 return (NULL);
 194         fp.fp_wsize = ntohs(tcp->th_win);
 195
 196
 197         cnt = (tcp->th_off << 2) - sizeof(*tcp);
 198         optp = (const u_int8_t *)((const char *)tcp + sizeof(*tcp));
 199         for (; cnt > 0; cnt -= optlen, optp += optlen) {
 200                 if (*optp == TCPOPT_EOL)
 201                         break;
 202
 203                 fp.fp_optcnt++;
 204                 if (*optp == TCPOPT_NOP) {
 205                         fp.fp_tcpopts = (fp.fp_tcpopts << PF_OSFP_TCPOPT_BITS) |
 206                             PF_OSFP_TCPOPT_NOP;
 207                         optlen = 1;
 208                 } else {
 209                         if (cnt < 2)
 210                                 return (NULL);
 211                         optlen = optp[1];
 212                         if (optlen > cnt || optlen < 2)
 213                                 return (NULL);
 214                         switch (*optp) {
 215                         case TCPOPT_MAXSEG:
 216                                 if (optlen >= TCPOLEN_MAXSEG)
 217                                         memcpy(&fp.fp_mss, &optp[2],
 218                                             sizeof(fp.fp_mss));
 219                                 fp.fp_tcpopts = (fp.fp_tcpopts <<
 220                                     PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_MSS;
 221                                 NTOHS(fp.fp_mss);
 222                                 break;
 223                         case TCPOPT_WINDOW:
 224                                 if (optlen >= TCPOLEN_WINDOW)
 225                                         memcpy(&fp.fp_wscale, &optp[2],
 226                                             sizeof(fp.fp_wscale));
 227                                 NTOHS(fp.fp_wscale);
 228                                 fp.fp_tcpopts = (fp.fp_tcpopts <<
 229                                     PF_OSFP_TCPOPT_BITS) |
 230                                     PF_OSFP_TCPOPT_WSCALE;
 231                                 break;
 232                         case TCPOPT_SACK_PERMITTED:
 233                                 fp.fp_tcpopts = (fp.fp_tcpopts <<
 234                                     PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_SACK;
 235                                 break;
 236                         case TCPOPT_TIMESTAMP:
 237                                 if (optlen >= TCPOLEN_TIMESTAMP) {
 238                                         u_int32_t ts;
 239                                         memcpy(&ts, &optp[2], sizeof(ts));
 240                                         if (ts == 0)
 241                                                 fp.fp_flags |= PF_OSFP_TS0;
 242
 243                                 }
 244                                 fp.fp_tcpopts = (fp.fp_tcpopts <<
 245                                     PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_TS;
 246                                 break;
 247                         default:
 248                                 return (NULL);
 249                         }
 250                 }
 251                 optlen = MAX(optlen, 1);        /* paranoia */
 252         }
 253
 254         DPFPRINTF("fingerprinted %s:%d  %d:%d:%d:%d:%llx (%d) "
 255             "(TS=%s,M=%s%d,W=%s%d)\n",
 256             srcname, ntohs(tcp->th_sport),
 257             fp.fp_wsize, fp.fp_ttl, (fp.fp_flags & PF_OSFP_DF) != 0,
 258             fp.fp_psize, (long long int)fp.fp_tcpopts, fp.fp_optcnt,
 259             (fp.fp_flags & PF_OSFP_TS0) ? "0" : "",
 260             (fp.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
 261             (fp.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
 262             fp.fp_mss,
 263             (fp.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
 264             (fp.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
 265             fp.fp_wscale);
 266
 267         if ((fpresult = pf_osfp_find(&pf_osfp_list, &fp,
 268             PF_OSFP_MAXTTL_OFFSET)))
 269                 return (&fpresult->fp_oses);
 270         return (NULL);
 271 }
 272
 273 /* Match a fingerprint ID against a list of OSes */
 274 int
 275 pf_osfp_match(struct pf_osfp_enlist *list, pf_osfp_t os)
 276 {
 277         struct pf_osfp_entry *entry;
 278         int os_class, os_version, os_subtype;
 279         int en_class, en_version, en_subtype;
 280
 281         if (os == PF_OSFP_ANY)
 282                 return (1);
 283         if (list == NULL) {
 284                 DPFPRINTF("osfp no match against %x\n", os);
 285                 return (os == PF_OSFP_UNKNOWN);
 286         }
 287         PF_OSFP_UNPACK(os, os_class, os_version, os_subtype);
 288         SLIST_FOREACH(entry, list, fp_entry) {
 289                 PF_OSFP_UNPACK(entry->fp_os, en_class, en_version, en_subtype);
 290                 if ((os_class == PF_OSFP_ANY || en_class == os_class) &&
 291                     (os_version == PF_OSFP_ANY || en_version == os_version) &&
 292                     (os_subtype == PF_OSFP_ANY || en_subtype == os_subtype)) {
 293                         DPFPRINTF("osfp matched %s %s %s  %x==%x\n",
 294                             entry->fp_class_nm, entry->fp_version_nm,
 295                             entry->fp_subtype_nm, os, entry->fp_os);
 296                         return (1);
 297                 }
 298         }
 299         DPFPRINTF("fingerprint 0x%x didn't match\n", os);
 300         return (0);
 301 }
 302
 303 /* Initialize the OS fingerprint system */
 304 #ifdef __FreeBSD__
 305 int
 306 #else
 307 void
 308 #endif
 309 pf_osfp_initialize(void)
 310 {
 311 #if defined(__FreeBSD__) && defined(_KERNEL)
 312         int error = ENOMEM;
 313
 314         do {
 315                 pf_osfp_entry_pl = pf_osfp_pl = NULL;
 316                 UMA_CREATE(pf_osfp_entry_pl, struct pf_osfp_entry, "pfospfen");
 317                 UMA_CREATE(pf_osfp_pl, struct pf_os_fingerprint, "pfosfp");
 318                 error = 0;
 319         } while(0);
 320 #else
 321         pool_init(&pf_osfp_entry_pl, sizeof(struct pf_osfp_entry), 0, 0, 0,
 322             "pfosfpen", &pool_allocator_nointr);
 323         pool_init(&pf_osfp_pl, sizeof(struct pf_os_fingerprint), 0, 0, 0,
 324             "pfosfp", &pool_allocator_nointr);
 325 #endif
 326         SLIST_INIT(&pf_osfp_list);
 327 #ifdef __FreeBSD__
 328 #ifdef _KERNEL
 329         return (error);
 330 #else
 331         return (0);
 332 #endif
 333 #endif
 334 }
 335
 336 #if defined(__FreeBSD__) && (_KERNEL)
 337 void
 338 pf_osfp_cleanup(void)
 339 {
 340         UMA_DESTROY(pf_osfp_entry_pl);
 341         UMA_DESTROY(pf_osfp_pl);
 342 }
 343 #endif
 344
 345 /* Flush the fingerprint list */
 346 void
 347 pf_osfp_flush(void)
 348 {
 349         struct pf_os_fingerprint *fp;
 350         struct pf_osfp_entry *entry;
 351
 352         while ((fp = SLIST_FIRST(&pf_osfp_list))) {
 353                 SLIST_REMOVE_HEAD(&pf_osfp_list, fp_next);
 354                 while ((entry = SLIST_FIRST(&fp->fp_oses))) {
 355                         SLIST_REMOVE_HEAD(&fp->fp_oses, fp_entry);
 356                         pool_put(&pf_osfp_entry_pl, entry);
 357                 }
 358                 pool_put(&pf_osfp_pl, fp);
 359         }
 360 }
 361
 362
 363 /* Add a fingerprint */
 364 int
 365 pf_osfp_add(struct pf_osfp_ioctl *fpioc)
 366 {
 367         struct pf_os_fingerprint *fp, fpadd;
 368         struct pf_osfp_entry *entry;
 369
 370         memset(&fpadd, 0, sizeof(fpadd));
 371         fpadd.fp_tcpopts = fpioc->fp_tcpopts;
 372         fpadd.fp_wsize = fpioc->fp_wsize;
 373         fpadd.fp_psize = fpioc->fp_psize;
 374         fpadd.fp_mss = fpioc->fp_mss;
 375         fpadd.fp_flags = fpioc->fp_flags;
 376         fpadd.fp_optcnt = fpioc->fp_optcnt;
 377         fpadd.fp_wscale = fpioc->fp_wscale;
 378         fpadd.fp_ttl = fpioc->fp_ttl;
 379
 380         DPFPRINTF("adding osfp %s %s %s = %s%d:%d:%d:%s%d:0x%llx %d "
 381             "(TS=%s,M=%s%d,W=%s%d) %x\n",
 382             fpioc->fp_os.fp_class_nm, fpioc->fp_os.fp_version_nm,
 383             fpioc->fp_os.fp_subtype_nm,
 384             (fpadd.fp_flags & PF_OSFP_WSIZE_MOD) ? "%" :
 385             (fpadd.fp_flags & PF_OSFP_WSIZE_MSS) ? "S" :
 386             (fpadd.fp_flags & PF_OSFP_WSIZE_MTU) ? "T" :
 387             (fpadd.fp_flags & PF_OSFP_WSIZE_DC) ? "*" : "",
 388             fpadd.fp_wsize,
 389             fpadd.fp_ttl,
 390             (fpadd.fp_flags & PF_OSFP_DF) ? 1 : 0,
 391             (fpadd.fp_flags & PF_OSFP_PSIZE_MOD) ? "%" :
 392             (fpadd.fp_flags & PF_OSFP_PSIZE_DC) ? "*" : "",
 393             fpadd.fp_psize,
 394             (long long int)fpadd.fp_tcpopts, fpadd.fp_optcnt,
 395             (fpadd.fp_flags & PF_OSFP_TS0) ? "0" : "",
 396             (fpadd.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
 397             (fpadd.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
 398             fpadd.fp_mss,
 399             (fpadd.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
 400             (fpadd.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
 401             fpadd.fp_wscale,
 402             fpioc->fp_os.fp_os);
 403
 404
 405         if ((fp = pf_osfp_find_exact(&pf_osfp_list, &fpadd))) {
 406                  SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
 407                         if (PF_OSFP_ENTRY_EQ(entry, &fpioc->fp_os))
 408                                 return (EEXIST);
 409                 }
 410                 if ((entry = pool_get(&pf_osfp_entry_pl, PR_NOWAIT)) == NULL)
 411                         return (ENOMEM);
 412         } else {
 413                 if ((fp = pool_get(&pf_osfp_pl, PR_NOWAIT)) == NULL)
 414                         return (ENOMEM);
 415                 memset(fp, 0, sizeof(*fp));
 416                 fp->fp_tcpopts = fpioc->fp_tcpopts;
 417                 fp->fp_wsize = fpioc->fp_wsize;
 418                 fp->fp_psize = fpioc->fp_psize;
 419                 fp->fp_mss = fpioc->fp_mss;
 420                 fp->fp_flags = fpioc->fp_flags;
 421                 fp->fp_optcnt = fpioc->fp_optcnt;
 422                 fp->fp_wscale = fpioc->fp_wscale;
 423                 fp->fp_ttl = fpioc->fp_ttl;
 424                 SLIST_INIT(&fp->fp_oses);
 425                 if ((entry = pool_get(&pf_osfp_entry_pl, PR_NOWAIT)) == NULL) {
 426                         pool_put(&pf_osfp_pl, fp);
 427                         return (ENOMEM);
 428                 }
 429                 pf_osfp_insert(&pf_osfp_list, fp);
 430         }
 431         memcpy(entry, &fpioc->fp_os, sizeof(*entry));
 432
 433         /* Make sure the strings are NUL terminated */
 434         entry->fp_class_nm[sizeof(entry->fp_class_nm)-1] = '\0';
 435         entry->fp_version_nm[sizeof(entry->fp_version_nm)-1] = '\0';
 436         entry->fp_subtype_nm[sizeof(entry->fp_subtype_nm)-1] = '\0';
 437
 438         SLIST_INSERT_HEAD(&fp->fp_oses, entry, fp_entry);
 439
 440 #ifdef PFDEBUG
 441         if ((fp = pf_osfp_validate()))
 442                 printf("Invalid fingerprint list\n");
 443 #endif /* PFDEBUG */
 444         return (0);
 445 }
 446
 447
 448 /* Find a fingerprint in the list */
 449 struct pf_os_fingerprint *
 450 pf_osfp_find(struct pf_osfp_list *list, struct pf_os_fingerprint *find,
 451     u_int8_t ttldiff)
 452 {
 453         struct pf_os_fingerprint *f;
 454
 455 #define MATCH_INT(_MOD, _DC, _field)                                    \
 456         if ((f->fp_flags & _DC) == 0) {                                 \
 457                 if ((f->fp_flags & _MOD) == 0) {                        \
 458                         if (f->_field != find->_field)                  \
 459                                 continue;                               \
 460                 } else {                                                \
 461                         if (f->_field == 0 || find->_field % f->_field) \
 462                                 continue;                               \
 463                 }                                                       \
 464         }
 465
 466         SLIST_FOREACH(f, list, fp_next) {
 467                 if (f->fp_tcpopts != find->fp_tcpopts ||
 468                     f->fp_optcnt != find->fp_optcnt ||
 469                     f->fp_ttl < find->fp_ttl ||
 470                     f->fp_ttl - find->fp_ttl > ttldiff ||
 471                     (f->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)) !=
 472                     (find->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)))
 473                         continue;
 474
 475                 MATCH_INT(PF_OSFP_PSIZE_MOD, PF_OSFP_PSIZE_DC, fp_psize)
 476                 MATCH_INT(PF_OSFP_MSS_MOD, PF_OSFP_MSS_DC, fp_mss)
 477                 MATCH_INT(PF_OSFP_WSCALE_MOD, PF_OSFP_WSCALE_DC, fp_wscale)
 478                 if ((f->fp_flags & PF_OSFP_WSIZE_DC) == 0) {
 479                         if (f->fp_flags & PF_OSFP_WSIZE_MSS) {
 480                                 if (find->fp_mss == 0)
 481                                         continue;
 482
 483 /* Some "smart" NAT devices and DSL routers will tweak the MSS size and
 484  * will set it to whatever is suitable for the link type.
 485  */
 486 #define SMART_MSS       1460
 487                                 if ((find->fp_wsize % find->fp_mss ||
 488                                     find->fp_wsize / find->fp_mss !=
 489                                     f->fp_wsize) &&
 490                                     (find->fp_wsize % SMART_MSS ||
 491                                     find->fp_wsize / SMART_MSS !=
 492                                     f->fp_wsize))
 493                                         continue;
 494                         } else if (f->fp_flags & PF_OSFP_WSIZE_MTU) {
 495                                 if (find->fp_mss == 0)
 496                                         continue;
 497
 498 #define MTUOFF  (sizeof(struct ip) + sizeof(struct tcphdr))
 499 #define SMART_MTU       (SMART_MSS + MTUOFF)
 500                                 if ((find->fp_wsize % (find->fp_mss + MTUOFF) ||
 501                                     find->fp_wsize / (find->fp_mss + MTUOFF) !=
 502                                     f->fp_wsize) &&
 503                                     (find->fp_wsize % SMART_MTU ||
 504                                     find->fp_wsize / SMART_MTU !=
 505                                     f->fp_wsize))
 506                                         continue;
 507                         } else if (f->fp_flags & PF_OSFP_WSIZE_MOD) {
 508                                 if (f->fp_wsize == 0 || find->fp_wsize %
 509                                     f->fp_wsize)
 510                                         continue;
 511                         } else {
 512                                 if (f->fp_wsize != find->fp_wsize)
 513                                         continue;
 514                         }
 515                 }
 516                 return (f);
 517         }
 518
 519         return (NULL);
 520 }
 521
 522 /* Find an exact fingerprint in the list */
 523 struct pf_os_fingerprint *
 524 pf_osfp_find_exact(struct pf_osfp_list *list, struct pf_os_fingerprint *find)
 525 {
 526         struct pf_os_fingerprint *f;
 527
 528         SLIST_FOREACH(f, list, fp_next) {
 529                 if (f->fp_tcpopts == find->fp_tcpopts &&
 530                     f->fp_wsize == find->fp_wsize &&
 531                     f->fp_psize == find->fp_psize &&
 532                     f->fp_mss == find->fp_mss &&
 533                     f->fp_flags == find->fp_flags &&
 534                     f->fp_optcnt == find->fp_optcnt &&
 535                     f->fp_wscale == find->fp_wscale &&
 536                     f->fp_ttl == find->fp_ttl)
 537                         return (f);
 538         }
 539
 540         return (NULL);
 541 }
 542
 543 /* Insert a fingerprint into the list */
 544 void
 545 pf_osfp_insert(struct pf_osfp_list *list, struct pf_os_fingerprint *ins)
 546 {
 547         struct pf_os_fingerprint *f, *prev = NULL;
 548
 549         /* XXX need to go semi tree based.  can key on tcp options */
 550
 551         SLIST_FOREACH(f, list, fp_next)
 552                 prev = f;
 553         if (prev)
 554                 SLIST_INSERT_AFTER(prev, ins, fp_next);
 555         else
 556                 SLIST_INSERT_HEAD(list, ins, fp_next);
 557 }
 558
 559 /* Fill a fingerprint by its number (from an ioctl) */
 560 int
 561 pf_osfp_get(struct pf_osfp_ioctl *fpioc)
 562 {
 563         struct pf_os_fingerprint *fp;
 564         struct pf_osfp_entry *entry;
 565         int num = fpioc->fp_getnum;
 566         int i = 0;
 567
 568
 569         memset(fpioc, 0, sizeof(*fpioc));
 570         SLIST_FOREACH(fp, &pf_osfp_list, fp_next) {
 571                 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
 572                         if (i++ == num) {
 573                                 fpioc->fp_mss = fp->fp_mss;
 574                                 fpioc->fp_wsize = fp->fp_wsize;
 575                                 fpioc->fp_flags = fp->fp_flags;
 576                                 fpioc->fp_psize = fp->fp_psize;
 577                                 fpioc->fp_ttl = fp->fp_ttl;
 578                                 fpioc->fp_wscale = fp->fp_wscale;
 579                                 fpioc->fp_getnum = num;
 580                                 memcpy(&fpioc->fp_os, entry,
 581                                     sizeof(fpioc->fp_os));
 582                                 return (0);
 583                         }
 584                 }
 585         }
 586
 587         return (EBUSY);
 588 }
 589
 590
 591 /* Validate that each signature is reachable */
 592 struct pf_os_fingerprint *
 593 pf_osfp_validate(void)
 594 {
 595         struct pf_os_fingerprint *f, *f2, find;
 596
 597         SLIST_FOREACH(f, &pf_osfp_list, fp_next) {
 598                 memcpy(&find, f, sizeof(find));
 599
 600                 /* We do a few MSS/th_win percolations to make things unique */
 601                 if (find.fp_mss == 0)
 602                         find.fp_mss = 128;
 603                 if (f->fp_flags & PF_OSFP_WSIZE_MSS)
 604                         find.fp_wsize *= find.fp_mss, 1;
 605                 else if (f->fp_flags & PF_OSFP_WSIZE_MTU)
 606                         find.fp_wsize *= (find.fp_mss + 40);
 607                 else if (f->fp_flags & PF_OSFP_WSIZE_MOD)
 608                         find.fp_wsize *= 2;
 609                 if (f != (f2 = pf_osfp_find(&pf_osfp_list, &find, 0))) {
 610                         if (f2)
 611                                 printf("Found \"%s %s %s\" instead of "
 612                                     "\"%s %s %s\"\n",
 613                                     SLIST_FIRST(&f2->fp_oses)->fp_class_nm,
 614                                     SLIST_FIRST(&f2->fp_oses)->fp_version_nm,
 615                                     SLIST_FIRST(&f2->fp_oses)->fp_subtype_nm,
 616                                     SLIST_FIRST(&f->fp_oses)->fp_class_nm,
 617                                     SLIST_FIRST(&f->fp_oses)->fp_version_nm,
 618                                     SLIST_FIRST(&f->fp_oses)->fp_subtype_nm);
 619                         else
 620                                 printf("Couldn't find \"%s %s %s\"\n",
 621                                     SLIST_FIRST(&f->fp_oses)->fp_class_nm,
 622                                     SLIST_FIRST(&f->fp_oses)->fp_version_nm,
 623                                     SLIST_FIRST(&f->fp_oses)->fp_subtype_nm);
 624                         return (f);
 625                 }
 626         }
 627         return (NULL);
 628 }