net/netfilter/nf_conntrack_sip.c

   1 /* SIP extension for IP connection tracking.
   2  *
   3  * (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar>
   4  * based on RR's ip_conntrack_ftp.c and other modules.
   5  * (C) 2007 United Security Providers
   6  * (C) 2007, 2008 Patrick McHardy <kaber@trash.net>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/ctype.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/inet.h>
  17 #include <linux/in.h>
  18 #include <linux/udp.h>
  19 #include <linux/netfilter.h>
  20
  21 #include <net/netfilter/nf_conntrack.h>
  22 #include <net/netfilter/nf_conntrack_core.h>
  23 #include <net/netfilter/nf_conntrack_expect.h>
  24 #include <net/netfilter/nf_conntrack_helper.h>
  25 #include <linux/netfilter/nf_conntrack_sip.h>
  26
  27 MODULE_LICENSE("GPL");
  28 MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
  29 MODULE_DESCRIPTION("SIP connection tracking helper");
  30 MODULE_ALIAS("ip_conntrack_sip");
  31 MODULE_ALIAS_NFCT_HELPER("sip");
  32
  33 #define MAX_PORTS       8
  34 static unsigned short ports[MAX_PORTS];
  35 static unsigned int ports_c;
  36 module_param_array(ports, ushort, &ports_c, 0400);
  37 MODULE_PARM_DESC(ports, "port numbers of SIP servers");
  38
  39 static unsigned int sip_timeout __read_mostly = SIP_TIMEOUT;
  40 module_param(sip_timeout, uint, 0600);
  41 MODULE_PARM_DESC(sip_timeout, "timeout for the master SIP session");
  42
  43 static int sip_direct_signalling __read_mostly = 1;
  44 module_param(sip_direct_signalling, int, 0600);
  45 MODULE_PARM_DESC(sip_direct_signalling, "expect incoming calls from registrar "
  46                                         "only (default 1)");
  47
  48 static int sip_direct_media __read_mostly = 1;
  49 module_param(sip_direct_media, int, 0600);
  50 MODULE_PARM_DESC(sip_direct_media, "Expect Media streams between signalling "
  51                                    "endpoints only (default 1)");
  52
  53 unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb,
  54                                 const char **dptr,
  55                                 unsigned int *datalen) __read_mostly;
  56 EXPORT_SYMBOL_GPL(nf_nat_sip_hook);
  57
  58 unsigned int (*nf_nat_sip_expect_hook)(struct sk_buff *skb,
  59                                        const char **dptr,
  60                                        unsigned int *datalen,
  61                                        struct nf_conntrack_expect *exp,
  62                                        unsigned int matchoff,
  63                                        unsigned int matchlen) __read_mostly;
  64 EXPORT_SYMBOL_GPL(nf_nat_sip_expect_hook);
  65
  66 unsigned int (*nf_nat_sdp_addr_hook)(struct sk_buff *skb,
  67                                      const char **dptr,
  68                                      unsigned int dataoff,
  69                                      unsigned int *datalen,
  70                                      enum sdp_header_types type,
  71                                      enum sdp_header_types term,
  72                                      const union nf_inet_addr *addr)
  73                                      __read_mostly;
  74 EXPORT_SYMBOL_GPL(nf_nat_sdp_addr_hook);
  75
  76 unsigned int (*nf_nat_sdp_port_hook)(struct sk_buff *skb,
  77                                      const char **dptr,
  78                                      unsigned int *datalen,
  79                                      unsigned int matchoff,
  80                                      unsigned int matchlen,
  81                                      u_int16_t port) __read_mostly;
  82 EXPORT_SYMBOL_GPL(nf_nat_sdp_port_hook);
  83
  84 unsigned int (*nf_nat_sdp_session_hook)(struct sk_buff *skb,
  85                                         const char **dptr,
  86                                         unsigned int dataoff,
  87                                         unsigned int *datalen,
  88                                         const union nf_inet_addr *addr)
  89                                         __read_mostly;
  90 EXPORT_SYMBOL_GPL(nf_nat_sdp_session_hook);
  91
  92 unsigned int (*nf_nat_sdp_media_hook)(struct sk_buff *skb,
  93                                       const char **dptr,
  94                                       unsigned int *datalen,
  95                                       struct nf_conntrack_expect *rtp_exp,
  96                                       struct nf_conntrack_expect *rtcp_exp,
  97                                       unsigned int mediaoff,
  98                                       unsigned int medialen,
  99                                       union nf_inet_addr *rtp_addr)
 100                                       __read_mostly;
 101 EXPORT_SYMBOL_GPL(nf_nat_sdp_media_hook);
 102
 103 static int string_len(const struct nf_conn *ct, const char *dptr,
 104                       const char *limit, int *shift)
 105 {
 106         int len = 0;
 107
 108         while (dptr < limit && isalpha(*dptr)) {
 109                 dptr++;
 110                 len++;
 111         }
 112         return len;
 113 }
 114
 115 static int digits_len(const struct nf_conn *ct, const char *dptr,
 116                       const char *limit, int *shift)
 117 {
 118         int len = 0;
 119         while (dptr < limit && isdigit(*dptr)) {
 120                 dptr++;
 121                 len++;
 122         }
 123         return len;
 124 }
 125
 126 /* get media type + port length */
 127 static int media_len(const struct nf_conn *ct, const char *dptr,
 128                      const char *limit, int *shift)
 129 {
 130         int len = string_len(ct, dptr, limit, shift);
 131
 132         dptr += len;
 133         if (dptr >= limit || *dptr != ' ')
 134                 return 0;
 135         len++;
 136         dptr++;
 137
 138         return len + digits_len(ct, dptr, limit, shift);
 139 }
 140
 141 static int parse_addr(const struct nf_conn *ct, const char *cp,
 142                       const char **endp, union nf_inet_addr *addr,
 143                       const char *limit)
 144 {
 145         const char *end;
 146         int ret = 0;
 147
 148         memset(addr, 0, sizeof(*addr));
 149         switch (nf_ct_l3num(ct)) {
 150         case AF_INET:
 151                 ret = in4_pton(cp, limit - cp, (u8 *)&addr->ip, -1, &end);
 152                 break;
 153         case AF_INET6:
 154                 ret = in6_pton(cp, limit - cp, (u8 *)&addr->ip6, -1, &end);
 155                 break;
 156         default:
 157                 BUG();
 158         }
 159
 160         if (ret == 0 || end == cp)
 161                 return 0;
 162         if (endp)
 163                 *endp = end;
 164         return 1;
 165 }
 166
 167 /* skip ip address. returns its length. */
 168 static int epaddr_len(const struct nf_conn *ct, const char *dptr,
 169                       const char *limit, int *shift)
 170 {
 171         union nf_inet_addr addr;
 172         const char *aux = dptr;
 173
 174         if (!parse_addr(ct, dptr, &dptr, &addr, limit)) {
 175                 pr_debug("ip: %s parse failed.!\n", dptr);
 176                 return 0;
 177         }
 178
 179         /* Port number */
 180         if (*dptr == ':') {
 181                 dptr++;
 182                 dptr += digits_len(ct, dptr, limit, shift);
 183         }
 184         return dptr - aux;
 185 }
 186
 187 /* get address length, skiping user info. */
 188 static int skp_epaddr_len(const struct nf_conn *ct, const char *dptr,
 189                           const char *limit, int *shift)
 190 {
 191         const char *start = dptr;
 192         int s = *shift;
 193
 194         /* Search for @, but stop at the end of the line.
 195          * We are inside a sip: URI, so we don't need to worry about
 196          * continuation lines. */
 197         while (dptr < limit &&
 198                *dptr != '@' && *dptr != '\r' && *dptr != '\n') {
 199                 (*shift)++;
 200                 dptr++;
 201         }
 202
 203         if (dptr < limit && *dptr == '@') {
 204                 dptr++;
 205                 (*shift)++;
 206         } else {
 207                 dptr = start;
 208                 *shift = s;
 209         }
 210
 211         return epaddr_len(ct, dptr, limit, shift);
 212 }
 213
 214 /* Parse a SIP request line of the form:
 215  *
 216  * Request-Line = Method SP Request-URI SP SIP-Version CRLF
 217  *
 218  * and return the offset and length of the address contained in the Request-URI.
 219  */
 220 int ct_sip_parse_request(const struct nf_conn *ct,
 221                          const char *dptr, unsigned int datalen,
 222                          unsigned int *matchoff, unsigned int *matchlen,
 223                          union nf_inet_addr *addr, __be16 *port)
 224 {
 225         const char *start = dptr, *limit = dptr + datalen, *end;
 226         unsigned int mlen;
 227         unsigned int p;
 228         int shift = 0;
 229
 230         /* Skip method and following whitespace */
 231         mlen = string_len(ct, dptr, limit, NULL);
 232         if (!mlen)
 233                 return 0;
 234         dptr += mlen;
 235         if (++dptr >= limit)
 236                 return 0;
 237
 238         /* Find SIP URI */
 239         limit -= strlen("sip:");
 240         for (; dptr < limit; dptr++) {
 241                 if (*dptr == '\r' || *dptr == '\n')
 242                         return -1;
 243                 if (strnicmp(dptr, "sip:", strlen("sip:")) == 0)
 244                         break;
 245         }
 246         if (!skp_epaddr_len(ct, dptr, limit, &shift))
 247                 return 0;
 248         dptr += shift;
 249
 250         if (!parse_addr(ct, dptr, &end, addr, limit))
 251                 return -1;
 252         if (end < limit && *end == ':') {
 253                 end++;
 254                 p = simple_strtoul(end, (char **)&end, 10);
 255                 if (p < 1024 || p > 65535)
 256                         return -1;
 257                 *port = htons(p);
 258         } else
 259                 *port = htons(SIP_PORT);
 260
 261         if (end == dptr)
 262                 return 0;
 263         *matchoff = dptr - start;
 264         *matchlen = end - dptr;
 265         return 1;
 266 }
 267 EXPORT_SYMBOL_GPL(ct_sip_parse_request);
 268
 269 /* SIP header parsing: SIP headers are located at the beginning of a line, but
 270  * may span several lines, in which case the continuation lines begin with a
 271  * whitespace character. RFC 2543 allows lines to be terminated with CR, LF or
 272  * CRLF, RFC 3261 allows only CRLF, we support both.
 273  *
 274  * Headers are followed by (optionally) whitespace, a colon, again (optionally)
 275  * whitespace and the values. Whitespace in this context means any amount of
 276  * tabs, spaces and continuation lines, which are treated as a single whitespace
 277  * character.
 278  *
 279  * Some headers may appear multiple times. A comma seperated list of values is
 280  * equivalent to multiple headers.
 281  */
 282 static const struct sip_header ct_sip_hdrs[] = {
 283         [SIP_HDR_CSEQ]                  = SIP_HDR("CSeq", NULL, NULL, digits_len),
 284         [SIP_HDR_FROM]                  = SIP_HDR("From", "f", "sip:", skp_epaddr_len),
 285         [SIP_HDR_TO]                    = SIP_HDR("To", "t", "sip:", skp_epaddr_len),
 286         [SIP_HDR_CONTACT]               = SIP_HDR("Contact", "m", "sip:", skp_epaddr_len),
 287         [SIP_HDR_VIA]                   = SIP_HDR("Via", "v", "UDP ", epaddr_len),
 288         [SIP_HDR_EXPIRES]               = SIP_HDR("Expires", NULL, NULL, digits_len),
 289         [SIP_HDR_CONTENT_LENGTH]        = SIP_HDR("Content-Length", "l", NULL, digits_len),
 290 };
 291
 292 static const char *sip_follow_continuation(const char *dptr, const char *limit)
 293 {
 294         /* Walk past newline */
 295         if (++dptr >= limit)
 296                 return NULL;
 297
 298         /* Skip '\n' in CR LF */
 299         if (*(dptr - 1) == '\r' && *dptr == '\n') {
 300                 if (++dptr >= limit)
 301                         return NULL;
 302         }
 303
 304         /* Continuation line? */
 305         if (*dptr != ' ' && *dptr != '\t')
 306                 return NULL;
 307
 308         /* skip leading whitespace */
 309         for (; dptr < limit; dptr++) {
 310                 if (*dptr != ' ' && *dptr != '\t')
 311                         break;
 312         }
 313         return dptr;
 314 }
 315
 316 static const char *sip_skip_whitespace(const char *dptr, const char *limit)
 317 {
 318         for (; dptr < limit; dptr++) {
 319                 if (*dptr == ' ')
 320                         continue;
 321                 if (*dptr != '\r' && *dptr != '\n')
 322                         break;
 323                 dptr = sip_follow_continuation(dptr, limit);
 324                 if (dptr == NULL)
 325                         return NULL;
 326         }
 327         return dptr;
 328 }
 329
 330 /* Search within a SIP header value, dealing with continuation lines */
 331 static const char *ct_sip_header_search(const char *dptr, const char *limit,
 332                                         const char *needle, unsigned int len)
 333 {
 334         for (limit -= len; dptr < limit; dptr++) {
 335                 if (*dptr == '\r' || *dptr == '\n') {
 336                         dptr = sip_follow_continuation(dptr, limit);
 337                         if (dptr == NULL)
 338                                 break;
 339                         continue;
 340                 }
 341
 342                 if (strnicmp(dptr, needle, len) == 0)
 343                         return dptr;
 344         }
 345         return NULL;
 346 }
 347
 348 int ct_sip_get_header(const struct nf_conn *ct, const char *dptr,
 349                       unsigned int dataoff, unsigned int datalen,
 350                       enum sip_header_types type,
 351                       unsigned int *matchoff, unsigned int *matchlen)
 352 {
 353         const struct sip_header *hdr = &ct_sip_hdrs[type];
 354         const char *start = dptr, *limit = dptr + datalen;
 355         int shift = 0;
 356
 357         for (dptr += dataoff; dptr < limit; dptr++) {
 358                 /* Find beginning of line */
 359                 if (*dptr != '\r' && *dptr != '\n')
 360                         continue;
 361                 if (++dptr >= limit)
 362                         break;
 363                 if (*(dptr - 1) == '\r' && *dptr == '\n') {
 364                         if (++dptr >= limit)
 365                                 break;
 366                 }
 367
 368                 /* Skip continuation lines */
 369                 if (*dptr == ' ' || *dptr == '\t')
 370                         continue;
 371
 372                 /* Find header. Compact headers must be followed by a
 373                  * non-alphabetic character to avoid mismatches. */
 374                 if (limit - dptr >= hdr->len &&
 375                     strnicmp(dptr, hdr->name, hdr->len) == 0)
 376                         dptr += hdr->len;
 377                 else if (hdr->cname && limit - dptr >= hdr->clen + 1 &&
 378                          strnicmp(dptr, hdr->cname, hdr->clen) == 0 &&
 379                          !isalpha(*(dptr + hdr->clen)))
 380                         dptr += hdr->clen;
 381                 else
 382                         continue;
 383
 384                 /* Find and skip colon */
 385                 dptr = sip_skip_whitespace(dptr, limit);
 386                 if (dptr == NULL)
 387                         break;
 388                 if (*dptr != ':' || ++dptr >= limit)
 389                         break;
 390
 391                 /* Skip whitespace after colon */
 392                 dptr = sip_skip_whitespace(dptr, limit);
 393                 if (dptr == NULL)
 394                         break;
 395
 396                 *matchoff = dptr - start;
 397                 if (hdr->search) {
 398                         dptr = ct_sip_header_search(dptr, limit, hdr->search,
 399                                                     hdr->slen);
 400                         if (!dptr)
 401                                 return -1;
 402                         dptr += hdr->slen;
 403                 }
 404
 405                 *matchlen = hdr->match_len(ct, dptr, limit, &shift);
 406                 if (!*matchlen)
 407                         return -1;
 408                 *matchoff = dptr - start + shift;
 409                 return 1;
 410         }
 411         return 0;
 412 }
 413 EXPORT_SYMBOL_GPL(ct_sip_get_header);
 414
 415 /* Get next header field in a list of comma seperated values */
 416 static int ct_sip_next_header(const struct nf_conn *ct, const char *dptr,
 417                               unsigned int dataoff, unsigned int datalen,
 418                               enum sip_header_types type,
 419                               unsigned int *matchoff, unsigned int *matchlen)
 420 {
 421         const struct sip_header *hdr = &ct_sip_hdrs[type];
 422         const char *start = dptr, *limit = dptr + datalen;
 423         int shift = 0;
 424
 425         dptr += dataoff;
 426
 427         dptr = ct_sip_header_search(dptr, limit, ",", strlen(","));
 428         if (!dptr)
 429                 return 0;
 430
 431         dptr = ct_sip_header_search(dptr, limit, hdr->search, hdr->slen);
 432         if (!dptr)
 433                 return 0;
 434         dptr += hdr->slen;
 435
 436         *matchoff = dptr - start;
 437         *matchlen = hdr->match_len(ct, dptr, limit, &shift);
 438         if (!*matchlen)
 439                 return -1;
 440         *matchoff += shift;
 441         return 1;
 442 }
 443
 444 /* Walk through headers until a parsable one is found or no header of the
 445  * given type is left. */
 446 static int ct_sip_walk_headers(const struct nf_conn *ct, const char *dptr,
 447                                unsigned int dataoff, unsigned int datalen,
 448                                enum sip_header_types type, int *in_header,
 449                                unsigned int *matchoff, unsigned int *matchlen)
 450 {
 451         int ret;
 452
 453         if (in_header && *in_header) {
 454                 while (1) {
 455                         ret = ct_sip_next_header(ct, dptr, dataoff, datalen,
 456                                                  type, matchoff, matchlen);
 457                         if (ret > 0)
 458                                 return ret;
 459                         if (ret == 0)
 460                                 break;
 461                         dataoff += *matchoff;
 462                 }
 463                 *in_header = 0;
 464         }
 465
 466         while (1) {
 467                 ret = ct_sip_get_header(ct, dptr, dataoff, datalen,
 468                                         type, matchoff, matchlen);
 469                 if (ret > 0)
 470                         break;
 471                 if (ret == 0)
 472                         return ret;
 473                 dataoff += *matchoff;
 474         }
 475
 476         if (in_header)
 477                 *in_header = 1;
 478         return 1;
 479 }
 480
 481 /* Locate a SIP header, parse the URI and return the offset and length of
 482  * the address as well as the address and port themselves. A stream of
 483  * headers can be parsed by handing in a non-NULL datalen and in_header
 484  * pointer.
 485  */
 486 int ct_sip_parse_header_uri(const struct nf_conn *ct, const char *dptr,
 487                             unsigned int *dataoff, unsigned int datalen,
 488                             enum sip_header_types type, int *in_header,
 489                             unsigned int *matchoff, unsigned int *matchlen,
 490                             union nf_inet_addr *addr, __be16 *port)
 491 {
 492         const char *c, *limit = dptr + datalen;
 493         unsigned int p;
 494         int ret;
 495
 496         ret = ct_sip_walk_headers(ct, dptr, dataoff ? *dataoff : 0, datalen,
 497                                   type, in_header, matchoff, matchlen);
 498         WARN_ON(ret < 0);
 499         if (ret == 0)
 500                 return ret;
 501
 502         if (!parse_addr(ct, dptr + *matchoff, &c, addr, limit))
 503                 return -1;
 504         if (*c == ':') {
 505                 c++;
 506                 p = simple_strtoul(c, (char **)&c, 10);
 507                 if (p < 1024 || p > 65535)
 508                         return -1;
 509                 *port = htons(p);
 510         } else
 511                 *port = htons(SIP_PORT);
 512
 513         if (dataoff)
 514                 *dataoff = c - dptr;
 515         return 1;
 516 }
 517 EXPORT_SYMBOL_GPL(ct_sip_parse_header_uri);
 518
 519 /* Parse address from header parameter and return address, offset and length */
 520 int ct_sip_parse_address_param(const struct nf_conn *ct, const char *dptr,
 521                                unsigned int dataoff, unsigned int datalen,
 522                                const char *name,
 523                                unsigned int *matchoff, unsigned int *matchlen,
 524                                union nf_inet_addr *addr)
 525 {
 526         const char *limit = dptr + datalen;
 527         const char *start, *end;
 528
 529         limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(","));
 530         if (!limit)
 531                 limit = dptr + datalen;
 532
 533         start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name));
 534         if (!start)
 535                 return 0;
 536
 537         start += strlen(name);
 538         if (!parse_addr(ct, start, &end, addr, limit))
 539                 return 0;
 540         *matchoff = start - dptr;
 541         *matchlen = end - start;
 542         return 1;
 543 }
 544 EXPORT_SYMBOL_GPL(ct_sip_parse_address_param);
 545
 546 /* Parse numerical header parameter and return value, offset and length */
 547 int ct_sip_parse_numerical_param(const struct nf_conn *ct, const char *dptr,
 548                                  unsigned int dataoff, unsigned int datalen,
 549                                  const char *name,
 550                                  unsigned int *matchoff, unsigned int *matchlen,
 551                                  unsigned int *val)
 552 {
 553         const char *limit = dptr + datalen;
 554         const char *start;
 555         char *end;
 556
 557         limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(","));
 558         if (!limit)
 559                 limit = dptr + datalen;
 560
 561         start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name));
 562         if (!start)
 563                 return 0;
 564
 565         start += strlen(name);
 566         *val = simple_strtoul(start, &end, 0);
 567         if (start == end)
 568                 return 0;
 569         if (matchoff && matchlen) {
 570                 *matchoff = start - dptr;
 571                 *matchlen = end - start;
 572         }
 573         return 1;
 574 }
 575 EXPORT_SYMBOL_GPL(ct_sip_parse_numerical_param);
 576
 577 /* SDP header parsing: a SDP session description contains an ordered set of
 578  * headers, starting with a section containing general session parameters,
 579  * optionally followed by multiple media descriptions.
 580  *
 581  * SDP headers always start at the beginning of a line. According to RFC 2327:
 582  * "The sequence CRLF (0x0d0a) is used to end a record, although parsers should
 583  * be tolerant and also accept records terminated with a single newline
 584  * character". We handle both cases.
 585  */
 586 static const struct sip_header ct_sdp_hdrs[] = {
 587         [SDP_HDR_VERSION]               = SDP_HDR("v=", NULL, digits_len),
 588         [SDP_HDR_OWNER_IP4]             = SDP_HDR("o=", "IN IP4 ", epaddr_len),
 589         [SDP_HDR_CONNECTION_IP4]        = SDP_HDR("c=", "IN IP4 ", epaddr_len),
 590         [SDP_HDR_OWNER_IP6]             = SDP_HDR("o=", "IN IP6 ", epaddr_len),
 591         [SDP_HDR_CONNECTION_IP6]        = SDP_HDR("c=", "IN IP6 ", epaddr_len),
 592         [SDP_HDR_MEDIA]                 = SDP_HDR("m=", NULL, media_len),
 593 };
 594
 595 /* Linear string search within SDP header values */
 596 static const char *ct_sdp_header_search(const char *dptr, const char *limit,
 597                                         const char *needle, unsigned int len)
 598 {
 599         for (limit -= len; dptr < limit; dptr++) {
 600                 if (*dptr == '\r' || *dptr == '\n')
 601                         break;
 602                 if (strncmp(dptr, needle, len) == 0)
 603                         return dptr;
 604         }
 605         return NULL;
 606 }
 607
 608 /* Locate a SDP header (optionally a substring within the header value),
 609  * optionally stopping at the first occurence of the term header, parse
 610  * it and return the offset and length of the data we're interested in.
 611  */
 612 int ct_sip_get_sdp_header(const struct nf_conn *ct, const char *dptr,
 613                           unsigned int dataoff, unsigned int datalen,
 614                           enum sdp_header_types type,
 615                           enum sdp_header_types term,
 616                           unsigned int *matchoff, unsigned int *matchlen)
 617 {
 618         const struct sip_header *hdr = &ct_sdp_hdrs[type];
 619         const struct sip_header *thdr = &ct_sdp_hdrs[term];
 620         const char *start = dptr, *limit = dptr + datalen;
 621         int shift = 0;
 622
 623         for (dptr += dataoff; dptr < limit; dptr++) {
 624                 /* Find beginning of line */
 625                 if (*dptr != '\r' && *dptr != '\n')
 626                         continue;
 627                 if (++dptr >= limit)
 628                         break;
 629                 if (*(dptr - 1) == '\r' && *dptr == '\n') {
 630                         if (++dptr >= limit)
 631                                 break;
 632                 }
 633
 634                 if (term != SDP_HDR_UNSPEC &&
 635                     limit - dptr >= thdr->len &&
 636                     strnicmp(dptr, thdr->name, thdr->len) == 0)
 637                         break;
 638                 else if (limit - dptr >= hdr->len &&
 639                          strnicmp(dptr, hdr->name, hdr->len) == 0)
 640                         dptr += hdr->len;
 641                 else
 642                         continue;
 643
 644                 *matchoff = dptr - start;
 645                 if (hdr->search) {
 646                         dptr = ct_sdp_header_search(dptr, limit, hdr->search,
 647                                                     hdr->slen);
 648                         if (!dptr)
 649                                 return -1;
 650                         dptr += hdr->slen;
 651                 }
 652
 653                 *matchlen = hdr->match_len(ct, dptr, limit, &shift);
 654                 if (!*matchlen)
 655                         return -1;
 656                 *matchoff = dptr - start + shift;
 657                 return 1;
 658         }
 659         return 0;
 660 }
 661 EXPORT_SYMBOL_GPL(ct_sip_get_sdp_header);
 662
 663 static int ct_sip_parse_sdp_addr(const struct nf_conn *ct, const char *dptr,
 664                                  unsigned int dataoff, unsigned int datalen,
 665                                  enum sdp_header_types type,
 666                                  enum sdp_header_types term,
 667                                  unsigned int *matchoff, unsigned int *matchlen,
 668                                  union nf_inet_addr *addr)
 669 {
 670         int ret;
 671
 672         ret = ct_sip_get_sdp_header(ct, dptr, dataoff, datalen, type, term,
 673                                     matchoff, matchlen);
 674         if (ret <= 0)
 675                 return ret;
 676
 677         if (!parse_addr(ct, dptr + *matchoff, NULL, addr,
 678                         dptr + *matchoff + *matchlen))
 679                 return -1;
 680         return 1;
 681 }
 682
 683 static int refresh_signalling_expectation(struct nf_conn *ct,
 684                                           union nf_inet_addr *addr,
 685                                           __be16 port,
 686                                           unsigned int expires)
 687 {
 688         struct nf_conn_help *help = nfct_help(ct);
 689         struct nf_conntrack_expect *exp;
 690         struct hlist_node *n, *next;
 691         int found = 0;
 692
 693         spin_lock_bh(&nf_conntrack_lock);
 694         hlist_for_each_entry_safe(exp, n, next, &help->expectations, lnode) {
 695                 if (exp->class != SIP_EXPECT_SIGNALLING ||
 696                     !nf_inet_addr_cmp(&exp->tuple.dst.u3, addr) ||
 697                     exp->tuple.dst.u.udp.port != port)
 698                         continue;
 699                 if (!del_timer(&exp->timeout))
 700                         continue;
 701                 exp->flags &= ~NF_CT_EXPECT_INACTIVE;
 702                 exp->timeout.expires = jiffies + expires * HZ;
 703                 add_timer(&exp->timeout);
 704                 found = 1;
 705                 break;
 706         }
 707         spin_unlock_bh(&nf_conntrack_lock);
 708         return found;
 709 }
 710
 711 static void flush_expectations(struct nf_conn *ct, bool media)
 712 {
 713         struct nf_conn_help *help = nfct_help(ct);
 714         struct nf_conntrack_expect *exp;
 715         struct hlist_node *n, *next;
 716
 717         spin_lock_bh(&nf_conntrack_lock);
 718         hlist_for_each_entry_safe(exp, n, next, &help->expectations, lnode) {
 719                 if ((exp->class != SIP_EXPECT_SIGNALLING) ^ media)
 720                         continue;
 721                 if (!del_timer(&exp->timeout))
 722                         continue;
 723                 nf_ct_unlink_expect(exp);
 724                 nf_ct_expect_put(exp);
 725                 if (!media)
 726                         break;
 727         }
 728         spin_unlock_bh(&nf_conntrack_lock);
 729 }
 730
 731 static int set_expected_rtp_rtcp(struct sk_buff *skb,
 732                                  const char **dptr, unsigned int *datalen,
 733                                  union nf_inet_addr *daddr, __be16 port,
 734                                  enum sip_expectation_classes class,
 735                                  unsigned int mediaoff, unsigned int medialen)
 736 {
 737         struct nf_conntrack_expect *exp, *rtp_exp, *rtcp_exp;
 738         enum ip_conntrack_info ctinfo;
 739         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
 740         struct net *net = nf_ct_net(ct);
 741         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 742         union nf_inet_addr *saddr;
 743         struct nf_conntrack_tuple tuple;
 744         int direct_rtp = 0, skip_expect = 0, ret = NF_DROP;
 745         u_int16_t base_port;
 746         __be16 rtp_port, rtcp_port;
 747         typeof(nf_nat_sdp_port_hook) nf_nat_sdp_port;
 748         typeof(nf_nat_sdp_media_hook) nf_nat_sdp_media;
 749
 750         saddr = NULL;
 751         if (sip_direct_media) {
 752                 if (!nf_inet_addr_cmp(daddr, &ct->tuplehash[dir].tuple.src.u3))
 753                         return NF_ACCEPT;
 754                 saddr = &ct->tuplehash[!dir].tuple.src.u3;
 755         }
 756
 757         /* We need to check whether the registration exists before attempting
 758          * to register it since we can see the same media description multiple
 759          * times on different connections in case multiple endpoints receive
 760          * the same call.
 761          *
 762          * RTP optimization: if we find a matching media channel expectation
 763          * and both the expectation and this connection are SNATed, we assume
 764          * both sides can reach each other directly and use the final
 765          * destination address from the expectation. We still need to keep
 766          * the NATed expectations for media that might arrive from the
 767          * outside, and additionally need to expect the direct RTP stream
 768          * in case it passes through us even without NAT.
 769          */
 770         memset(&tuple, 0, sizeof(tuple));
 771         if (saddr)
 772                 tuple.src.u3 = *saddr;
 773         tuple.src.l3num         = nf_ct_l3num(ct);
 774         tuple.dst.protonum      = IPPROTO_UDP;
 775         tuple.dst.u3            = *daddr;
 776         tuple.dst.u.udp.port    = port;
 777
 778         rcu_read_lock();
 779         do {
 780                 exp = __nf_ct_expect_find(net, &tuple);
 781
 782                 if (!exp || exp->master == ct ||
 783                     nfct_help(exp->master)->helper != nfct_help(ct)->helper ||
 784                     exp->class != class)
 785                         break;
 786 #ifdef CONFIG_NF_NAT_NEEDED
 787                 if (exp->tuple.src.l3num == AF_INET && !direct_rtp &&
 788                     (exp->saved_ip != exp->tuple.dst.u3.ip ||
 789                      exp->saved_proto.udp.port != exp->tuple.dst.u.udp.port) &&
 790                     ct->status & IPS_NAT_MASK) {
 791                         daddr->ip               = exp->saved_ip;
 792                         tuple.dst.u3.ip         = exp->saved_ip;
 793                         tuple.dst.u.udp.port    = exp->saved_proto.udp.port;
 794                         direct_rtp = 1;
 795                 } else
 796 #endif
 797                         skip_expect = 1;
 798         } while (!skip_expect);
 799         rcu_read_unlock();
 800
 801         base_port = ntohs(tuple.dst.u.udp.port) & ~1;
 802         rtp_port = htons(base_port);
 803         rtcp_port = htons(base_port + 1);
 804
 805         if (direct_rtp) {
 806                 nf_nat_sdp_port = rcu_dereference(nf_nat_sdp_port_hook);
 807                 if (nf_nat_sdp_port &&
 808                     !nf_nat_sdp_port(skb, dptr, datalen,
 809                                      mediaoff, medialen, ntohs(rtp_port)))
 810                         goto err1;
 811         }
 812
 813         if (skip_expect)
 814                 return NF_ACCEPT;
 815
 816         rtp_exp = nf_ct_expect_alloc(ct);
 817         if (rtp_exp == NULL)
 818                 goto err1;
 819         nf_ct_expect_init(rtp_exp, class, nf_ct_l3num(ct), saddr, daddr,
 820                           IPPROTO_UDP, NULL, &rtp_port);
 821
 822         rtcp_exp = nf_ct_expect_alloc(ct);
 823         if (rtcp_exp == NULL)
 824                 goto err2;
 825         nf_ct_expect_init(rtcp_exp, class, nf_ct_l3num(ct), saddr, daddr,
 826                           IPPROTO_UDP, NULL, &rtcp_port);
 827
 828         nf_nat_sdp_media = rcu_dereference(nf_nat_sdp_media_hook);
 829         if (nf_nat_sdp_media && ct->status & IPS_NAT_MASK && !direct_rtp)
 830                 ret = nf_nat_sdp_media(skb, dptr, datalen, rtp_exp, rtcp_exp,
 831                                        mediaoff, medialen, daddr);
 832         else {
 833                 if (nf_ct_expect_related(rtp_exp) == 0) {
 834                         if (nf_ct_expect_related(rtcp_exp) != 0)
 835                                 nf_ct_unexpect_related(rtp_exp);
 836                         else
 837                                 ret = NF_ACCEPT;
 838                 }
 839         }
 840         nf_ct_expect_put(rtcp_exp);
 841 err2:
 842         nf_ct_expect_put(rtp_exp);
 843 err1:
 844         return ret;
 845 }
 846
 847 static const struct sdp_media_type sdp_media_types[] = {
 848         SDP_MEDIA_TYPE("audio ", SIP_EXPECT_AUDIO),
 849         SDP_MEDIA_TYPE("video ", SIP_EXPECT_VIDEO),
 850 };
 851
 852 static const struct sdp_media_type *sdp_media_type(const char *dptr,
 853                                                    unsigned int matchoff,
 854                                                    unsigned int matchlen)
 855 {
 856         const struct sdp_media_type *t;
 857         unsigned int i;
 858
 859         for (i = 0; i < ARRAY_SIZE(sdp_media_types); i++) {
 860                 t = &sdp_media_types[i];
 861                 if (matchlen < t->len ||
 862                     strncmp(dptr + matchoff, t->name, t->len))
 863                         continue;
 864                 return t;
 865         }
 866         return NULL;
 867 }
 868
 869 static int process_sdp(struct sk_buff *skb,
 870                        const char **dptr, unsigned int *datalen,
 871                        unsigned int cseq)
 872 {
 873         enum ip_conntrack_info ctinfo;
 874         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
 875         struct nf_conn_help *help = nfct_help(ct);
 876         unsigned int matchoff, matchlen;
 877         unsigned int mediaoff, medialen;
 878         unsigned int sdpoff;
 879         unsigned int caddr_len, maddr_len;
 880         unsigned int i;
 881         union nf_inet_addr caddr, maddr, rtp_addr;
 882         unsigned int port;
 883         enum sdp_header_types c_hdr;
 884         const struct sdp_media_type *t;
 885         int ret = NF_ACCEPT;
 886         typeof(nf_nat_sdp_addr_hook) nf_nat_sdp_addr;
 887         typeof(nf_nat_sdp_session_hook) nf_nat_sdp_session;
 888
 889         nf_nat_sdp_addr = rcu_dereference(nf_nat_sdp_addr_hook);
 890         c_hdr = nf_ct_l3num(ct) == AF_INET ? SDP_HDR_CONNECTION_IP4 :
 891                                              SDP_HDR_CONNECTION_IP6;
 892
 893         /* Find beginning of session description */
 894         if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen,
 895                                   SDP_HDR_VERSION, SDP_HDR_UNSPEC,
 896                                   &matchoff, &matchlen) <= 0)
 897                 return NF_ACCEPT;
 898         sdpoff = matchoff;
 899
 900         /* The connection information is contained in the session description
 901          * and/or once per media description. The first media description marks
 902          * the end of the session description. */
 903         caddr_len = 0;
 904         if (ct_sip_parse_sdp_addr(ct, *dptr, sdpoff, *datalen,
 905                                   c_hdr, SDP_HDR_MEDIA,
 906                                   &matchoff, &matchlen, &caddr) > 0)
 907                 caddr_len = matchlen;
 908
 909         mediaoff = sdpoff;
 910         for (i = 0; i < ARRAY_SIZE(sdp_media_types); ) {
 911                 if (ct_sip_get_sdp_header(ct, *dptr, mediaoff, *datalen,
 912                                           SDP_HDR_MEDIA, SDP_HDR_UNSPEC,
 913                                           &mediaoff, &medialen) <= 0)
 914                         break;
 915
 916                 /* Get media type and port number. A media port value of zero
 917                  * indicates an inactive stream. */
 918                 t = sdp_media_type(*dptr, mediaoff, medialen);
 919                 if (!t) {
 920                         mediaoff += medialen;
 921                         continue;
 922                 }
 923                 mediaoff += t->len;
 924                 medialen -= t->len;
 925
 926                 port = simple_strtoul(*dptr + mediaoff, NULL, 10);
 927                 if (port == 0)
 928                         continue;
 929                 if (port < 1024 || port > 65535)
 930                         return NF_DROP;
 931
 932                 /* The media description overrides the session description. */
 933                 maddr_len = 0;
 934                 if (ct_sip_parse_sdp_addr(ct, *dptr, mediaoff, *datalen,
 935                                           c_hdr, SDP_HDR_MEDIA,
 936                                           &matchoff, &matchlen, &maddr) > 0) {
 937                         maddr_len = matchlen;
 938                         memcpy(&rtp_addr, &maddr, sizeof(rtp_addr));
 939                 } else if (caddr_len)
 940                         memcpy(&rtp_addr, &caddr, sizeof(rtp_addr));
 941                 else
 942                         return NF_DROP;
 943
 944                 ret = set_expected_rtp_rtcp(skb, dptr, datalen,
 945                                             &rtp_addr, htons(port), t->class,
 946                                             mediaoff, medialen);
 947                 if (ret != NF_ACCEPT)
 948                         return ret;
 949
 950                 /* Update media connection address if present */
 951                 if (maddr_len && nf_nat_sdp_addr && ct->status & IPS_NAT_MASK) {
 952                         ret = nf_nat_sdp_addr(skb, dptr, mediaoff, datalen,
 953                                               c_hdr, SDP_HDR_MEDIA, &rtp_addr);
 954                         if (ret != NF_ACCEPT)
 955                                 return ret;
 956                 }
 957                 i++;
 958         }
 959
 960         /* Update session connection and owner addresses */
 961         nf_nat_sdp_session = rcu_dereference(nf_nat_sdp_session_hook);
 962         if (nf_nat_sdp_session && ct->status & IPS_NAT_MASK)
 963                 ret = nf_nat_sdp_session(skb, dptr, sdpoff, datalen, &rtp_addr);
 964
 965         if (ret == NF_ACCEPT && i > 0)
 966                 help->help.ct_sip_info.invite_cseq = cseq;
 967
 968         return ret;
 969 }
 970 static int process_invite_response(struct sk_buff *skb,
 971                                    const char **dptr, unsigned int *datalen,
 972                                    unsigned int cseq, unsigned int code)
 973 {
 974         enum ip_conntrack_info ctinfo;
 975         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
 976         struct nf_conn_help *help = nfct_help(ct);
 977
 978         if ((code >= 100 && code <= 199) ||
 979             (code >= 200 && code <= 299))
 980                 return process_sdp(skb, dptr, datalen, cseq);
 981         else if (help->help.ct_sip_info.invite_cseq == cseq)
 982                 flush_expectations(ct, true);
 983         return NF_ACCEPT;
 984 }
 985
 986 static int process_update_response(struct sk_buff *skb,
 987                                    const char **dptr, unsigned int *datalen,
 988                                    unsigned int cseq, unsigned int code)
 989 {
 990         enum ip_conntrack_info ctinfo;
 991         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
 992         struct nf_conn_help *help = nfct_help(ct);
 993
 994         if ((code >= 100 && code <= 199) ||
 995             (code >= 200 && code <= 299))
 996                 return process_sdp(skb, dptr, datalen, cseq);
 997         else if (help->help.ct_sip_info.invite_cseq == cseq)
 998                 flush_expectations(ct, true);
 999         return NF_ACCEPT;
1000 }
1001
1002 static int process_prack_response(struct sk_buff *skb,
1003                                   const char **dptr, unsigned int *datalen,
1004                                   unsigned int cseq, unsigned int code)
1005 {
1006         enum ip_conntrack_info ctinfo;
1007         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1008         struct nf_conn_help *help = nfct_help(ct);
1009
1010         if ((code >= 100 && code <= 199) ||
1011             (code >= 200 && code <= 299))
1012                 return process_sdp(skb, dptr, datalen, cseq);
1013         else if (help->help.ct_sip_info.invite_cseq == cseq)
1014                 flush_expectations(ct, true);
1015         return NF_ACCEPT;
1016 }
1017
1018 static int process_bye_request(struct sk_buff *skb,
1019                                const char **dptr, unsigned int *datalen,
1020                                unsigned int cseq)
1021 {
1022         enum ip_conntrack_info ctinfo;
1023         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1024
1025         flush_expectations(ct, true);
1026         return NF_ACCEPT;
1027 }
1028
1029 /* Parse a REGISTER request and create a permanent expectation for incoming
1030  * signalling connections. The expectation is marked inactive and is activated
1031  * when receiving a response indicating success from the registrar.
1032  */
1033 static int process_register_request(struct sk_buff *skb,
1034                                     const char **dptr, unsigned int *datalen,
1035                                     unsigned int cseq)
1036 {
1037         enum ip_conntrack_info ctinfo;
1038         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1039         struct nf_conn_help *help = nfct_help(ct);
1040         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
1041         unsigned int matchoff, matchlen;
1042         struct nf_conntrack_expect *exp;
1043         union nf_inet_addr *saddr, daddr;
1044         __be16 port;
1045         unsigned int expires = 0;
1046         int ret;
1047         typeof(nf_nat_sip_expect_hook) nf_nat_sip_expect;
1048
1049         /* Expected connections can not register again. */
1050         if (ct->status & IPS_EXPECTED)
1051                 return NF_ACCEPT;
1052
1053         /* We must check the expiration time: a value of zero signals the
1054          * registrar to release the binding. We'll remove our expectation
1055          * when receiving the new bindings in the response, but we don't
1056          * want to create new ones.
1057          *
1058          * The expiration time may be contained in Expires: header, the
1059          * Contact: header parameters or the URI parameters.
1060          */
1061         if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES,
1062                               &matchoff, &matchlen) > 0)
1063                 expires = simple_strtoul(*dptr + matchoff, NULL, 10);
1064
1065         ret = ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
1066                                       SIP_HDR_CONTACT, NULL,
1067                                       &matchoff, &matchlen, &daddr, &port);
1068         if (ret < 0)
1069                 return NF_DROP;
1070         else if (ret == 0)
1071                 return NF_ACCEPT;
1072
1073         /* We don't support third-party registrations */
1074         if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, &daddr))
1075                 return NF_ACCEPT;
1076
1077         if (ct_sip_parse_numerical_param(ct, *dptr,
1078                                          matchoff + matchlen, *datalen,
1079                                          "expires=", NULL, NULL, &expires) < 0)
1080                 return NF_DROP;
1081
1082         if (expires == 0) {
1083                 ret = NF_ACCEPT;
1084                 goto store_cseq;
1085         }
1086
1087         exp = nf_ct_expect_alloc(ct);
1088         if (!exp)
1089                 return NF_DROP;
1090
1091         saddr = NULL;
1092         if (sip_direct_signalling)
1093                 saddr = &ct->tuplehash[!dir].tuple.src.u3;
1094
1095         nf_ct_expect_init(exp, SIP_EXPECT_SIGNALLING, nf_ct_l3num(ct),
1096                           saddr, &daddr, IPPROTO_UDP, NULL, &port);
1097         exp->timeout.expires = sip_timeout * HZ;
1098         exp->helper = nfct_help(ct)->helper;
1099         exp->flags = NF_CT_EXPECT_PERMANENT | NF_CT_EXPECT_INACTIVE;
1100
1101         nf_nat_sip_expect = rcu_dereference(nf_nat_sip_expect_hook);
1102         if (nf_nat_sip_expect && ct->status & IPS_NAT_MASK)
1103                 ret = nf_nat_sip_expect(skb, dptr, datalen, exp,
1104                                         matchoff, matchlen);
1105         else {
1106                 if (nf_ct_expect_related(exp) != 0)
1107                         ret = NF_DROP;
1108                 else
1109                         ret = NF_ACCEPT;
1110         }
1111         nf_ct_expect_put(exp);
1112
1113 store_cseq:
1114         if (ret == NF_ACCEPT)
1115                 help->help.ct_sip_info.register_cseq = cseq;
1116         return ret;
1117 }
1118
1119 static int process_register_response(struct sk_buff *skb,
1120                                      const char **dptr, unsigned int *datalen,
1121                                      unsigned int cseq, unsigned int code)
1122 {
1123         enum ip_conntrack_info ctinfo;
1124         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1125         struct nf_conn_help *help = nfct_help(ct);
1126         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
1127         union nf_inet_addr addr;
1128         __be16 port;
1129         unsigned int matchoff, matchlen, dataoff = 0;
1130         unsigned int expires = 0;
1131         int in_contact = 0, ret;
1132
1133         /* According to RFC 3261, "UAs MUST NOT send a new registration until
1134          * they have received a final response from the registrar for the
1135          * previous one or the previous REGISTER request has timed out".
1136          *
1137          * However, some servers fail to detect retransmissions and send late
1138          * responses, so we store the sequence number of the last valid
1139          * request and compare it here.
1140          */
1141         if (help->help.ct_sip_info.register_cseq != cseq)
1142                 return NF_ACCEPT;
1143
1144         if (code >= 100 && code <= 199)
1145                 return NF_ACCEPT;
1146         if (code < 200 || code > 299)
1147                 goto flush;
1148
1149         if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES,
1150                               &matchoff, &matchlen) > 0)
1151                 expires = simple_strtoul(*dptr + matchoff, NULL, 10);
1152
1153         while (1) {
1154                 unsigned int c_expires = expires;
1155
1156                 ret = ct_sip_parse_header_uri(ct, *dptr, &dataoff, *datalen,
1157                                               SIP_HDR_CONTACT, &in_contact,
1158                                               &matchoff, &matchlen,
1159                                               &addr, &port);
1160                 if (ret < 0)
1161                         return NF_DROP;
1162                 else if (ret == 0)
1163                         break;
1164
1165                 /* We don't support third-party registrations */
1166                 if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, &addr))
1167                         continue;
1168
1169                 ret = ct_sip_parse_numerical_param(ct, *dptr,
1170                                                    matchoff + matchlen,
1171                                                    *datalen, "expires=",
1172                                                    NULL, NULL, &c_expires);
1173                 if (ret < 0)
1174                         return NF_DROP;
1175                 if (c_expires == 0)
1176                         break;
1177                 if (refresh_signalling_expectation(ct, &addr, port, c_expires))
1178                         return NF_ACCEPT;
1179         }
1180
1181 flush:
1182         flush_expectations(ct, false);
1183         return NF_ACCEPT;
1184 }
1185
1186 static const struct sip_handler sip_handlers[] = {
1187         SIP_HANDLER("INVITE", process_sdp, process_invite_response),
1188         SIP_HANDLER("UPDATE", process_sdp, process_update_response),
1189         SIP_HANDLER("ACK", process_sdp, NULL),
1190         SIP_HANDLER("PRACK", process_sdp, process_prack_response),
1191         SIP_HANDLER("BYE", process_bye_request, NULL),
1192         SIP_HANDLER("REGISTER", process_register_request, process_register_response),
1193 };
1194
1195 static int process_sip_response(struct sk_buff *skb,
1196                                 const char **dptr, unsigned int *datalen)
1197 {
1198         enum ip_conntrack_info ctinfo;
1199         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1200         unsigned int matchoff, matchlen;
1201         unsigned int code, cseq, dataoff, i;
1202
1203         if (*datalen < strlen("SIP/2.0 200"))
1204                 return NF_ACCEPT;
1205         code = simple_strtoul(*dptr + strlen("SIP/2.0 "), NULL, 10);
1206         if (!code)
1207                 return NF_DROP;
1208
1209         if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ,
1210                               &matchoff, &matchlen) <= 0)
1211                 return NF_DROP;
1212         cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
1213         if (!cseq)
1214                 return NF_DROP;
1215         dataoff = matchoff + matchlen + 1;
1216
1217         for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) {
1218                 const struct sip_handler *handler;
1219
1220                 handler = &sip_handlers[i];
1221                 if (handler->response == NULL)
1222                         continue;
1223                 if (*datalen < dataoff + handler->len ||
1224                     strnicmp(*dptr + dataoff, handler->method, handler->len))
1225                         continue;
1226                 return handler->response(skb, dptr, datalen, cseq, code);
1227         }
1228         return NF_ACCEPT;
1229 }
1230
1231 static int process_sip_request(struct sk_buff *skb,
1232                                const char **dptr, unsigned int *datalen)
1233 {
1234         enum ip_conntrack_info ctinfo;
1235         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1236         unsigned int matchoff, matchlen;
1237         unsigned int cseq, i;
1238
1239         for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) {
1240                 const struct sip_handler *handler;
1241
1242                 handler = &sip_handlers[i];
1243                 if (handler->request == NULL)
1244                         continue;
1245                 if (*datalen < handler->len ||
1246                     strnicmp(*dptr, handler->method, handler->len))
1247                         continue;
1248
1249                 if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ,
1250                                       &matchoff, &matchlen) <= 0)
1251                         return NF_DROP;
1252                 cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
1253                 if (!cseq)
1254                         return NF_DROP;
1255
1256                 return handler->request(skb, dptr, datalen, cseq);
1257         }
1258         return NF_ACCEPT;
1259 }
1260
1261 static int sip_help(struct sk_buff *skb,
1262                     unsigned int protoff,
1263                     struct nf_conn *ct,
1264                     enum ip_conntrack_info ctinfo)
1265 {
1266         unsigned int dataoff, datalen;
1267         const char *dptr;
1268         int ret;
1269         typeof(nf_nat_sip_hook) nf_nat_sip;
1270
1271         /* No Data ? */
1272         dataoff = protoff + sizeof(struct udphdr);
1273         if (dataoff >= skb->len)
1274                 return NF_ACCEPT;
1275
1276         nf_ct_refresh(ct, skb, sip_timeout * HZ);
1277
1278         if (!skb_is_nonlinear(skb))
1279                 dptr = skb->data + dataoff;
1280         else {
1281                 pr_debug("Copy of skbuff not supported yet.\n");
1282                 return NF_ACCEPT;
1283         }
1284
1285         datalen = skb->len - dataoff;
1286         if (datalen < strlen("SIP/2.0 200"))
1287                 return NF_ACCEPT;
1288
1289         if (strnicmp(dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0)
1290                 ret = process_sip_request(skb, &dptr, &datalen);
1291         else
1292                 ret = process_sip_response(skb, &dptr, &datalen);
1293
1294         if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
1295                 nf_nat_sip = rcu_dereference(nf_nat_sip_hook);
1296                 if (nf_nat_sip && !nf_nat_sip(skb, &dptr, &datalen))
1297                         ret = NF_DROP;
1298         }
1299
1300         return ret;
1301 }
1302
1303 static struct nf_conntrack_helper sip[MAX_PORTS][2] __read_mostly;
1304 static char sip_names[MAX_PORTS][2][sizeof("sip-65535")] __read_mostly;
1305
1306 static const struct nf_conntrack_expect_policy sip_exp_policy[SIP_EXPECT_MAX + 1] = {
1307         [SIP_EXPECT_SIGNALLING] = {
1308                 .max_expected   = 1,
1309                 .timeout        = 3 * 60,
1310         },
1311         [SIP_EXPECT_AUDIO] = {
1312                 .max_expected   = 2 * IP_CT_DIR_MAX,
1313                 .timeout        = 3 * 60,
1314         },
1315         [SIP_EXPECT_VIDEO] = {
1316                 .max_expected   = 2 * IP_CT_DIR_MAX,
1317                 .timeout        = 3 * 60,
1318         },
1319 };
1320
1321 static void nf_conntrack_sip_fini(void)
1322 {
1323         int i, j;
1324
1325         for (i = 0; i < ports_c; i++) {
1326                 for (j = 0; j < 2; j++) {
1327                         if (sip[i][j].me == NULL)
1328                                 continue;
1329                         nf_conntrack_helper_unregister(&sip[i][j]);
1330                 }
1331         }
1332 }
1333
1334 static int __init nf_conntrack_sip_init(void)
1335 {
1336         int i, j, ret;
1337         char *tmpname;
1338
1339         if (ports_c == 0)
1340                 ports[ports_c++] = SIP_PORT;
1341
1342         for (i = 0; i < ports_c; i++) {
1343                 memset(&sip[i], 0, sizeof(sip[i]));
1344
1345                 sip[i][0].tuple.src.l3num = AF_INET;
1346                 sip[i][1].tuple.src.l3num = AF_INET6;
1347                 for (j = 0; j < 2; j++) {
1348                         sip[i][j].tuple.dst.protonum = IPPROTO_UDP;
1349                         sip[i][j].tuple.src.u.udp.port = htons(ports[i]);
1350                         sip[i][j].expect_policy = sip_exp_policy;
1351                         sip[i][j].expect_class_max = SIP_EXPECT_MAX;
1352                         sip[i][j].me = THIS_MODULE;
1353                         sip[i][j].help = sip_help;
1354
1355                         tmpname = &sip_names[i][j][0];
1356                         if (ports[i] == SIP_PORT)
1357                                 sprintf(tmpname, "sip");
1358                         else
1359                                 sprintf(tmpname, "sip-%u", i);
1360                         sip[i][j].name = tmpname;
1361
1362                         pr_debug("port #%u: %u\n", i, ports[i]);
1363
1364                         ret = nf_conntrack_helper_register(&sip[i][j]);
1365                         if (ret) {
1366                                 printk("nf_ct_sip: failed to register helper "
1367                                        "for pf: %u port: %u\n",
1368                                        sip[i][j].tuple.src.l3num, ports[i]);
1369                                 nf_conntrack_sip_fini();
1370                                 return ret;
1371                         }
1372                 }
1373         }
1374         return 0;
1375 }
1376
1377 module_init(nf_conntrack_sip_init);
1378 module_exit(nf_conntrack_sip_fini);