net/sched/cls_rsvp.h

   1 /*
   2  * net/sched/cls_rsvp.h Template file for RSVPv[46] classifiers.
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10  */
  11
  12 /*
  13    Comparing to general packet classification problem,
  14    RSVP needs only sevaral relatively simple rules:
  15
  16    * (dst, protocol) are always specified,
  17      so that we are able to hash them.
  18    * src may be exact, or may be wildcard, so that
  19      we can keep a hash table plus one wildcard entry.
  20    * source port (or flow label) is important only if src is given.
  21
  22    IMPLEMENTATION.
  23
  24    We use a two level hash table: The top level is keyed by
  25    destination address and protocol ID, every bucket contains a list
  26    of "rsvp sessions", identified by destination address, protocol and
  27    DPI(="Destination Port ID"): triple (key, mask, offset).
  28
  29    Every bucket has a smaller hash table keyed by source address
  30    (cf. RSVP flowspec) and one wildcard entry for wildcard reservations.
  31    Every bucket is again a list of "RSVP flows", selected by
  32    source address and SPI(="Source Port ID" here rather than
  33    "security parameter index"): triple (key, mask, offset).
  34
  35
  36    NOTE 1. All the packets with IPv6 extension headers (but AH and ESP)
  37    and all fragmented packets go to the best-effort traffic class.
  38
  39
  40    NOTE 2. Two "port id"'s seems to be redundant, rfc2207 requires
  41    only one "Generalized Port Identifier". So that for classic
  42    ah, esp (and udp,tcp) both *pi should coincide or one of them
  43    should be wildcard.
  44
  45    At first sight, this redundancy is just a waste of CPU
  46    resources. But DPI and SPI add the possibility to assign different
  47    priorities to GPIs. Look also at note 4 about tunnels below.
  48
  49
  50    NOTE 3. One complication is the case of tunneled packets.
  51    We implement it as following: if the first lookup
  52    matches a special session with "tunnelhdr" value not zero,
  53    flowid doesn't contain the true flow ID, but the tunnel ID (1...255).
  54    In this case, we pull tunnelhdr bytes and restart lookup
  55    with tunnel ID added to the list of keys. Simple and stupid 8)8)
  56    It's enough for PIMREG and IPIP.
  57
  58
  59    NOTE 4. Two GPIs make it possible to parse even GRE packets.
  60    F.e. DPI can select ETH_P_IP (and necessary flags to make
  61    tunnelhdr correct) in GRE protocol field and SPI matches
  62    GRE key. Is it not nice? 8)8)
  63
  64
  65    Well, as result, despite its simplicity, we get a pretty
  66    powerful classification engine.  */
  67
  68
  69 struct rsvp_head
  70 {
  71         u32                     tmap[256/32];
  72         u32                     hgenerator;
  73         u8                      tgenerator;
  74         struct rsvp_session     *ht[256];
  75 };
  76
  77 struct rsvp_session
  78 {
  79         struct rsvp_session     *next;
  80         __be32                  dst[RSVP_DST_LEN];
  81         struct tc_rsvp_gpi      dpi;
  82         u8                      protocol;
  83         u8                      tunnelid;
  84         /* 16 (src,sport) hash slots, and one wildcard source slot */
  85         struct rsvp_filter      *ht[16+1];
  86 };
  87
  88
  89 struct rsvp_filter
  90 {
  91         struct rsvp_filter      *next;
  92         __be32                  src[RSVP_DST_LEN];
  93         struct tc_rsvp_gpi      spi;
  94         u8                      tunnelhdr;
  95
  96         struct tcf_result       res;
  97         struct tcf_exts         exts;
  98
  99         u32                     handle;
 100         struct rsvp_session     *sess;
 101 };
 102
 103 static __inline__ unsigned hash_dst(__be32 *dst, u8 protocol, u8 tunnelid)
 104 {
 105         unsigned h = (__force __u32)dst[RSVP_DST_LEN-1];
 106         h ^= h>>16;
 107         h ^= h>>8;
 108         return (h ^ protocol ^ tunnelid) & 0xFF;
 109 }
 110
 111 static __inline__ unsigned hash_src(__be32 *src)
 112 {
 113         unsigned h = (__force __u32)src[RSVP_DST_LEN-1];
 114         h ^= h>>16;
 115         h ^= h>>8;
 116         h ^= h>>4;
 117         return h & 0xF;
 118 }
 119
 120 static struct tcf_ext_map rsvp_ext_map = {
 121         .police = TCA_RSVP_POLICE,
 122         .action = TCA_RSVP_ACT
 123 };
 124
 125 #define RSVP_APPLY_RESULT()                             \
 126 {                                                       \
 127         int r = tcf_exts_exec(skb, &f->exts, res);      \
 128         if (r < 0)                                      \
 129                 continue;                               \
 130         else if (r > 0)                                 \
 131                 return r;                               \
 132 }
 133
 134 static int rsvp_classify(struct sk_buff *skb, struct tcf_proto *tp,
 135                          struct tcf_result *res)
 136 {
 137         struct rsvp_session **sht = ((struct rsvp_head*)tp->root)->ht;
 138         struct rsvp_session *s;
 139         struct rsvp_filter *f;
 140         unsigned h1, h2;
 141         __be32 *dst, *src;
 142         u8 protocol;
 143         u8 tunnelid = 0;
 144         u8 *xprt;
 145 #if RSVP_DST_LEN == 4
 146         struct ipv6hdr *nhptr;
 147
 148         if (!pskb_network_may_pull(skb, sizeof(*nhptr)))
 149                 return -1;
 150         nhptr = ipv6_hdr(skb);
 151 #else
 152         struct iphdr *nhptr;
 153
 154         if (!pskb_network_may_pull(skb, sizeof(*nhptr)))
 155                 return -1;
 156         nhptr = ip_hdr(skb);
 157 #endif
 158
 159 restart:
 160
 161 #if RSVP_DST_LEN == 4
 162         src = &nhptr->saddr.s6_addr32[0];
 163         dst = &nhptr->daddr.s6_addr32[0];
 164         protocol = nhptr->nexthdr;
 165         xprt = ((u8*)nhptr) + sizeof(struct ipv6hdr);
 166 #else
 167         src = &nhptr->saddr;
 168         dst = &nhptr->daddr;
 169         protocol = nhptr->protocol;
 170         xprt = ((u8*)nhptr) + (nhptr->ihl<<2);
 171         if (nhptr->frag_off & htons(IP_MF|IP_OFFSET))
 172                 return -1;
 173 #endif
 174
 175         h1 = hash_dst(dst, protocol, tunnelid);
 176         h2 = hash_src(src);
 177
 178         for (s = sht[h1]; s; s = s->next) {
 179                 if (dst[RSVP_DST_LEN-1] == s->dst[RSVP_DST_LEN-1] &&
 180                     protocol == s->protocol &&
 181                     !(s->dpi.mask &
 182                       (*(u32*)(xprt+s->dpi.offset)^s->dpi.key)) &&
 183 #if RSVP_DST_LEN == 4
 184                     dst[0] == s->dst[0] &&
 185                     dst[1] == s->dst[1] &&
 186                     dst[2] == s->dst[2] &&
 187 #endif
 188                     tunnelid == s->tunnelid) {
 189
 190                         for (f = s->ht[h2]; f; f = f->next) {
 191                                 if (src[RSVP_DST_LEN-1] == f->src[RSVP_DST_LEN-1] &&
 192                                     !(f->spi.mask & (*(u32*)(xprt+f->spi.offset)^f->spi.key))
 193 #if RSVP_DST_LEN == 4
 194                                     &&
 195                                     src[0] == f->src[0] &&
 196                                     src[1] == f->src[1] &&
 197                                     src[2] == f->src[2]
 198 #endif
 199                                     ) {
 200                                         *res = f->res;
 201                                         RSVP_APPLY_RESULT();
 202
 203 matched:
 204                                         if (f->tunnelhdr == 0)
 205                                                 return 0;
 206
 207                                         tunnelid = f->res.classid;
 208                                         nhptr = (void*)(xprt + f->tunnelhdr - sizeof(*nhptr));
 209                                         goto restart;
 210                                 }
 211                         }
 212
 213                         /* And wildcard bucket... */
 214                         for (f = s->ht[16]; f; f = f->next) {
 215                                 *res = f->res;
 216                                 RSVP_APPLY_RESULT();
 217                                 goto matched;
 218                         }
 219                         return -1;
 220                 }
 221         }
 222         return -1;
 223 }
 224
 225 static unsigned long rsvp_get(struct tcf_proto *tp, u32 handle)
 226 {
 227         struct rsvp_session **sht = ((struct rsvp_head*)tp->root)->ht;
 228         struct rsvp_session *s;
 229         struct rsvp_filter *f;
 230         unsigned h1 = handle&0xFF;
 231         unsigned h2 = (handle>>8)&0xFF;
 232
 233         if (h2 > 16)
 234                 return 0;
 235
 236         for (s = sht[h1]; s; s = s->next) {
 237                 for (f = s->ht[h2]; f; f = f->next) {
 238                         if (f->handle == handle)
 239                                 return (unsigned long)f;
 240                 }
 241         }
 242         return 0;
 243 }
 244
 245 static void rsvp_put(struct tcf_proto *tp, unsigned long f)
 246 {
 247 }
 248
 249 static int rsvp_init(struct tcf_proto *tp)
 250 {
 251         struct rsvp_head *data;
 252
 253         data = kzalloc(sizeof(struct rsvp_head), GFP_KERNEL);
 254         if (data) {
 255                 tp->root = data;
 256                 return 0;
 257         }
 258         return -ENOBUFS;
 259 }
 260
 261 static inline void
 262 rsvp_delete_filter(struct tcf_proto *tp, struct rsvp_filter *f)
 263 {
 264         tcf_unbind_filter(tp, &f->res);
 265         tcf_exts_destroy(tp, &f->exts);
 266         kfree(f);
 267 }
 268
 269 static void rsvp_destroy(struct tcf_proto *tp)
 270 {
 271         struct rsvp_head *data = xchg(&tp->root, NULL);
 272         struct rsvp_session **sht;
 273         int h1, h2;
 274
 275         if (data == NULL)
 276                 return;
 277
 278         sht = data->ht;
 279
 280         for (h1=0; h1<256; h1++) {
 281                 struct rsvp_session *s;
 282
 283                 while ((s = sht[h1]) != NULL) {
 284                         sht[h1] = s->next;
 285
 286                         for (h2=0; h2<=16; h2++) {
 287                                 struct rsvp_filter *f;
 288
 289                                 while ((f = s->ht[h2]) != NULL) {
 290                                         s->ht[h2] = f->next;
 291                                         rsvp_delete_filter(tp, f);
 292                                 }
 293                         }
 294                         kfree(s);
 295                 }
 296         }
 297         kfree(data);
 298 }
 299
 300 static int rsvp_delete(struct tcf_proto *tp, unsigned long arg)
 301 {
 302         struct rsvp_filter **fp, *f = (struct rsvp_filter*)arg;
 303         unsigned h = f->handle;
 304         struct rsvp_session **sp;
 305         struct rsvp_session *s = f->sess;
 306         int i;
 307
 308         for (fp = &s->ht[(h>>8)&0xFF]; *fp; fp = &(*fp)->next) {
 309                 if (*fp == f) {
 310                         tcf_tree_lock(tp);
 311                         *fp = f->next;
 312                         tcf_tree_unlock(tp);
 313                         rsvp_delete_filter(tp, f);
 314
 315                         /* Strip tree */
 316
 317                         for (i=0; i<=16; i++)
 318                                 if (s->ht[i])
 319                                         return 0;
 320
 321                         /* OK, session has no flows */
 322                         for (sp = &((struct rsvp_head*)tp->root)->ht[h&0xFF];
 323                              *sp; sp = &(*sp)->next) {
 324                                 if (*sp == s) {
 325                                         tcf_tree_lock(tp);
 326                                         *sp = s->next;
 327                                         tcf_tree_unlock(tp);
 328
 329                                         kfree(s);
 330                                         return 0;
 331                                 }
 332                         }
 333
 334                         return 0;
 335                 }
 336         }
 337         return 0;
 338 }
 339
 340 static unsigned gen_handle(struct tcf_proto *tp, unsigned salt)
 341 {
 342         struct rsvp_head *data = tp->root;
 343         int i = 0xFFFF;
 344
 345         while (i-- > 0) {
 346                 u32 h;
 347                 if ((data->hgenerator += 0x10000) == 0)
 348                         data->hgenerator = 0x10000;
 349                 h = data->hgenerator|salt;
 350                 if (rsvp_get(tp, h) == 0)
 351                         return h;
 352         }
 353         return 0;
 354 }
 355
 356 static int tunnel_bts(struct rsvp_head *data)
 357 {
 358         int n = data->tgenerator>>5;
 359         u32 b = 1<<(data->tgenerator&0x1F);
 360
 361         if (data->tmap[n]&b)
 362                 return 0;
 363         data->tmap[n] |= b;
 364         return 1;
 365 }
 366
 367 static void tunnel_recycle(struct rsvp_head *data)
 368 {
 369         struct rsvp_session **sht = data->ht;
 370         u32 tmap[256/32];
 371         int h1, h2;
 372
 373         memset(tmap, 0, sizeof(tmap));
 374
 375         for (h1=0; h1<256; h1++) {
 376                 struct rsvp_session *s;
 377                 for (s = sht[h1]; s; s = s->next) {
 378                         for (h2=0; h2<=16; h2++) {
 379                                 struct rsvp_filter *f;
 380
 381                                 for (f = s->ht[h2]; f; f = f->next) {
 382                                         if (f->tunnelhdr == 0)
 383                                                 continue;
 384                                         data->tgenerator = f->res.classid;
 385                                         tunnel_bts(data);
 386                                 }
 387                         }
 388                 }
 389         }
 390
 391         memcpy(data->tmap, tmap, sizeof(tmap));
 392 }
 393
 394 static u32 gen_tunnel(struct rsvp_head *data)
 395 {
 396         int i, k;
 397
 398         for (k=0; k<2; k++) {
 399                 for (i=255; i>0; i--) {
 400                         if (++data->tgenerator == 0)
 401                                 data->tgenerator = 1;
 402                         if (tunnel_bts(data))
 403                                 return data->tgenerator;
 404                 }
 405                 tunnel_recycle(data);
 406         }
 407         return 0;
 408 }
 409
 410 static const struct nla_policy rsvp_policy[TCA_RSVP_MAX + 1] = {
 411         [TCA_RSVP_CLASSID]      = { .type = NLA_U32 },
 412         [TCA_RSVP_DST]          = { .type = NLA_BINARY,
 413                                     .len = RSVP_DST_LEN * sizeof(u32) },
 414         [TCA_RSVP_SRC]          = { .type = NLA_BINARY,
 415                                     .len = RSVP_DST_LEN * sizeof(u32) },
 416         [TCA_RSVP_PINFO]        = { .len = sizeof(struct tc_rsvp_pinfo) },
 417 };
 418
 419 static int rsvp_change(struct tcf_proto *tp, unsigned long base,
 420                        u32 handle,
 421                        struct nlattr **tca,
 422                        unsigned long *arg)
 423 {
 424         struct rsvp_head *data = tp->root;
 425         struct rsvp_filter *f, **fp;
 426         struct rsvp_session *s, **sp;
 427         struct tc_rsvp_pinfo *pinfo = NULL;
 428         struct nlattr *opt = tca[TCA_OPTIONS-1];
 429         struct nlattr *tb[TCA_RSVP_MAX + 1];
 430         struct tcf_exts e;
 431         unsigned h1, h2;
 432         __be32 *dst;
 433         int err;
 434
 435         if (opt == NULL)
 436                 return handle ? -EINVAL : 0;
 437
 438         err = nla_parse_nested(tb, TCA_RSVP_MAX, opt, rsvp_policy);
 439         if (err < 0)
 440                 return err;
 441
 442         err = tcf_exts_validate(tp, tb, tca[TCA_RATE-1], &e, &rsvp_ext_map);
 443         if (err < 0)
 444                 return err;
 445
 446         if ((f = (struct rsvp_filter*)*arg) != NULL) {
 447                 /* Node exists: adjust only classid */
 448
 449                 if (f->handle != handle && handle)
 450                         goto errout2;
 451                 if (tb[TCA_RSVP_CLASSID-1]) {
 452                         f->res.classid = nla_get_u32(tb[TCA_RSVP_CLASSID-1]);
 453                         tcf_bind_filter(tp, &f->res, base);
 454                 }
 455
 456                 tcf_exts_change(tp, &f->exts, &e);
 457                 return 0;
 458         }
 459
 460         /* Now more serious part... */
 461         err = -EINVAL;
 462         if (handle)
 463                 goto errout2;
 464         if (tb[TCA_RSVP_DST-1] == NULL)
 465                 goto errout2;
 466
 467         err = -ENOBUFS;
 468         f = kzalloc(sizeof(struct rsvp_filter), GFP_KERNEL);
 469         if (f == NULL)
 470                 goto errout2;
 471
 472         h2 = 16;
 473         if (tb[TCA_RSVP_SRC-1]) {
 474                 memcpy(f->src, nla_data(tb[TCA_RSVP_SRC-1]), sizeof(f->src));
 475                 h2 = hash_src(f->src);
 476         }
 477         if (tb[TCA_RSVP_PINFO-1]) {
 478                 pinfo = nla_data(tb[TCA_RSVP_PINFO-1]);
 479                 f->spi = pinfo->spi;
 480                 f->tunnelhdr = pinfo->tunnelhdr;
 481         }
 482         if (tb[TCA_RSVP_CLASSID-1])
 483                 f->res.classid = nla_get_u32(tb[TCA_RSVP_CLASSID-1]);
 484
 485         dst = nla_data(tb[TCA_RSVP_DST-1]);
 486         h1 = hash_dst(dst, pinfo ? pinfo->protocol : 0, pinfo ? pinfo->tunnelid : 0);
 487
 488         err = -ENOMEM;
 489         if ((f->handle = gen_handle(tp, h1 | (h2<<8))) == 0)
 490                 goto errout;
 491
 492         if (f->tunnelhdr) {
 493                 err = -EINVAL;
 494                 if (f->res.classid > 255)
 495                         goto errout;
 496
 497                 err = -ENOMEM;
 498                 if (f->res.classid == 0 &&
 499                     (f->res.classid = gen_tunnel(data)) == 0)
 500                         goto errout;
 501         }
 502
 503         for (sp = &data->ht[h1]; (s=*sp) != NULL; sp = &s->next) {
 504                 if (dst[RSVP_DST_LEN-1] == s->dst[RSVP_DST_LEN-1] &&
 505                     pinfo && pinfo->protocol == s->protocol &&
 506                     memcmp(&pinfo->dpi, &s->dpi, sizeof(s->dpi)) == 0 &&
 507 #if RSVP_DST_LEN == 4
 508                     dst[0] == s->dst[0] &&
 509                     dst[1] == s->dst[1] &&
 510                     dst[2] == s->dst[2] &&
 511 #endif
 512                     pinfo->tunnelid == s->tunnelid) {
 513
 514 insert:
 515                         /* OK, we found appropriate session */
 516
 517                         fp = &s->ht[h2];
 518
 519                         f->sess = s;
 520                         if (f->tunnelhdr == 0)
 521                                 tcf_bind_filter(tp, &f->res, base);
 522
 523                         tcf_exts_change(tp, &f->exts, &e);
 524
 525                         for (fp = &s->ht[h2]; *fp; fp = &(*fp)->next)
 526                                 if (((*fp)->spi.mask&f->spi.mask) != f->spi.mask)
 527                                         break;
 528                         f->next = *fp;
 529                         wmb();
 530                         *fp = f;
 531
 532                         *arg = (unsigned long)f;
 533                         return 0;
 534                 }
 535         }
 536
 537         /* No session found. Create new one. */
 538
 539         err = -ENOBUFS;
 540         s = kzalloc(sizeof(struct rsvp_session), GFP_KERNEL);
 541         if (s == NULL)
 542                 goto errout;
 543         memcpy(s->dst, dst, sizeof(s->dst));
 544
 545         if (pinfo) {
 546                 s->dpi = pinfo->dpi;
 547                 s->protocol = pinfo->protocol;
 548                 s->tunnelid = pinfo->tunnelid;
 549         }
 550         for (sp = &data->ht[h1]; *sp; sp = &(*sp)->next) {
 551                 if (((*sp)->dpi.mask&s->dpi.mask) != s->dpi.mask)
 552                         break;
 553         }
 554         s->next = *sp;
 555         wmb();
 556         *sp = s;
 557
 558         goto insert;
 559
 560 errout:
 561         kfree(f);
 562 errout2:
 563         tcf_exts_destroy(tp, &e);
 564         return err;
 565 }
 566
 567 static void rsvp_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 568 {
 569         struct rsvp_head *head = tp->root;
 570         unsigned h, h1;
 571
 572         if (arg->stop)
 573                 return;
 574
 575         for (h = 0; h < 256; h++) {
 576                 struct rsvp_session *s;
 577
 578                 for (s = head->ht[h]; s; s = s->next) {
 579                         for (h1 = 0; h1 <= 16; h1++) {
 580                                 struct rsvp_filter *f;
 581
 582                                 for (f = s->ht[h1]; f; f = f->next) {
 583                                         if (arg->count < arg->skip) {
 584                                                 arg->count++;
 585                                                 continue;
 586                                         }
 587                                         if (arg->fn(tp, (unsigned long)f, arg) < 0) {
 588                                                 arg->stop = 1;
 589                                                 return;
 590                                         }
 591                                         arg->count++;
 592                                 }
 593                         }
 594                 }
 595         }
 596 }
 597
 598 static int rsvp_dump(struct tcf_proto *tp, unsigned long fh,
 599                      struct sk_buff *skb, struct tcmsg *t)
 600 {
 601         struct rsvp_filter *f = (struct rsvp_filter*)fh;
 602         struct rsvp_session *s;
 603         unsigned char *b = skb_tail_pointer(skb);
 604         struct nlattr *nest;
 605         struct tc_rsvp_pinfo pinfo;
 606
 607         if (f == NULL)
 608                 return skb->len;
 609         s = f->sess;
 610
 611         t->tcm_handle = f->handle;
 612
 613         nest = nla_nest_start(skb, TCA_OPTIONS);
 614         if (nest == NULL)
 615                 goto nla_put_failure;
 616
 617         NLA_PUT(skb, TCA_RSVP_DST, sizeof(s->dst), &s->dst);
 618         pinfo.dpi = s->dpi;
 619         pinfo.spi = f->spi;
 620         pinfo.protocol = s->protocol;
 621         pinfo.tunnelid = s->tunnelid;
 622         pinfo.tunnelhdr = f->tunnelhdr;
 623         pinfo.pad = 0;
 624         NLA_PUT(skb, TCA_RSVP_PINFO, sizeof(pinfo), &pinfo);
 625         if (f->res.classid)
 626                 NLA_PUT_U32(skb, TCA_RSVP_CLASSID, f->res.classid);
 627         if (((f->handle>>8)&0xFF) != 16)
 628                 NLA_PUT(skb, TCA_RSVP_SRC, sizeof(f->src), f->src);
 629
 630         if (tcf_exts_dump(skb, &f->exts, &rsvp_ext_map) < 0)
 631                 goto nla_put_failure;
 632
 633         nla_nest_end(skb, nest);
 634
 635         if (tcf_exts_dump_stats(skb, &f->exts, &rsvp_ext_map) < 0)
 636                 goto nla_put_failure;
 637         return skb->len;
 638
 639 nla_put_failure:
 640         nlmsg_trim(skb, b);
 641         return -1;
 642 }
 643
 644 static struct tcf_proto_ops RSVP_OPS = {
 645         .next           =       NULL,
 646         .kind           =       RSVP_ID,
 647         .classify       =       rsvp_classify,
 648         .init           =       rsvp_init,
 649         .destroy        =       rsvp_destroy,
 650         .get            =       rsvp_get,
 651         .put            =       rsvp_put,
 652         .change         =       rsvp_change,
 653         .delete         =       rsvp_delete,
 654         .walk           =       rsvp_walk,
 655         .dump           =       rsvp_dump,
 656         .owner          =       THIS_MODULE,
 657 };
 658
 659 static int __init init_rsvp(void)
 660 {
 661         return register_tcf_proto_ops(&RSVP_OPS);
 662 }
 663
 664 static void __exit exit_rsvp(void)
 665 {
 666         unregister_tcf_proto_ops(&RSVP_OPS);
 667 }
 668
 669 module_init(init_rsvp)
 670 module_exit(exit_rsvp)