net/sctp/chunk.c

   1 /* SCTP kernel implementation
   2  * (C) Copyright IBM Corp. 2003, 2004
   3  *
   4  * This file is part of the SCTP kernel implementation
   5  *
   6  * This file contains the code relating the chunk abstraction.
   7  *
   8  * This SCTP implementation is free software;
   9  * you can redistribute it and/or modify it under the terms of
  10  * the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2, or (at your option)
  12  * any later version.
  13  *
  14  * This SCTP implementation is distributed in the hope that it
  15  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  16  *                 ************************
  17  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  18  * See the GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with GNU CC; see the file COPYING.  If not, write to
  22  * the Free Software Foundation, 59 Temple Place - Suite 330,
  23  * Boston, MA 02111-1307, USA.
  24  *
  25  * Please send any bug reports or fixes you make to the
  26  * email address(es):
  27  *    lksctp developers <lksctp-developers@lists.sourceforge.net>
  28  *
  29  * Or submit a bug report through the following website:
  30  *    http://www.sf.net/projects/lksctp
  31  *
  32  * Written or modified by:
  33  *    Jon Grimm             <jgrimm@us.ibm.com>
  34  *    Sridhar Samudrala     <sri@us.ibm.com>
  35  *
  36  * Any bugs reported given to us we will try to fix... any fixes shared will
  37  * be incorporated into the next SCTP release.
  38  */
  39
  40 #include <linux/types.h>
  41 #include <linux/kernel.h>
  42 #include <linux/net.h>
  43 #include <linux/inet.h>
  44 #include <linux/skbuff.h>
  45 #include <linux/slab.h>
  46 #include <net/sock.h>
  47 #include <net/sctp/sctp.h>
  48 #include <net/sctp/sm.h>
  49
  50 /* This file is mostly in anticipation of future work, but initially
  51  * populate with fragment tracking for an outbound message.
  52  */
  53
  54 /* Initialize datamsg from memory. */
  55 static void sctp_datamsg_init(struct sctp_datamsg *msg)
  56 {
  57         atomic_set(&msg->refcnt, 1);
  58         msg->send_failed = 0;
  59         msg->send_error = 0;
  60         msg->can_abandon = 0;
  61         msg->can_delay = 1;
  62         msg->expires_at = 0;
  63         INIT_LIST_HEAD(&msg->chunks);
  64 }
  65
  66 /* Allocate and initialize datamsg. */
  67 SCTP_STATIC struct sctp_datamsg *sctp_datamsg_new(gfp_t gfp)
  68 {
  69         struct sctp_datamsg *msg;
  70         msg = kmalloc(sizeof(struct sctp_datamsg), gfp);
  71         if (msg) {
  72                 sctp_datamsg_init(msg);
  73                 SCTP_DBG_OBJCNT_INC(datamsg);
  74         }
  75         return msg;
  76 }
  77
  78 void sctp_datamsg_free(struct sctp_datamsg *msg)
  79 {
  80         struct sctp_chunk *chunk;
  81
  82         /* This doesn't have to be a _safe vairant because
  83          * sctp_chunk_free() only drops the refs.
  84          */
  85         list_for_each_entry(chunk, &msg->chunks, frag_list)
  86                 sctp_chunk_free(chunk);
  87
  88         sctp_datamsg_put(msg);
  89 }
  90
  91 /* Final destructruction of datamsg memory. */
  92 static void sctp_datamsg_destroy(struct sctp_datamsg *msg)
  93 {
  94         struct list_head *pos, *temp;
  95         struct sctp_chunk *chunk;
  96         struct sctp_sock *sp;
  97         struct sctp_ulpevent *ev;
  98         struct sctp_association *asoc = NULL;
  99         int error = 0, notify;
 100
 101         /* If we failed, we may need to notify. */
 102         notify = msg->send_failed ? -1 : 0;
 103
 104         /* Release all references. */
 105         list_for_each_safe(pos, temp, &msg->chunks) {
 106                 list_del_init(pos);
 107                 chunk = list_entry(pos, struct sctp_chunk, frag_list);
 108                 /* Check whether we _really_ need to notify. */
 109                 if (notify < 0) {
 110                         asoc = chunk->asoc;
 111                         if (msg->send_error)
 112                                 error = msg->send_error;
 113                         else
 114                                 error = asoc->outqueue.error;
 115
 116                         sp = sctp_sk(asoc->base.sk);
 117                         notify = sctp_ulpevent_type_enabled(SCTP_SEND_FAILED,
 118                                                             &sp->subscribe);
 119                 }
 120
 121                 /* Generate a SEND FAILED event only if enabled. */
 122                 if (notify > 0) {
 123                         int sent;
 124                         if (chunk->has_tsn)
 125                                 sent = SCTP_DATA_SENT;
 126                         else
 127                                 sent = SCTP_DATA_UNSENT;
 128
 129                         ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent,
 130                                                             error, GFP_ATOMIC);
 131                         if (ev)
 132                                 sctp_ulpq_tail_event(&asoc->ulpq, ev);
 133                 }
 134
 135                 sctp_chunk_put(chunk);
 136         }
 137
 138         SCTP_DBG_OBJCNT_DEC(datamsg);
 139         kfree(msg);
 140 }
 141
 142 /* Hold a reference. */
 143 static void sctp_datamsg_hold(struct sctp_datamsg *msg)
 144 {
 145         atomic_inc(&msg->refcnt);
 146 }
 147
 148 /* Release a reference. */
 149 void sctp_datamsg_put(struct sctp_datamsg *msg)
 150 {
 151         if (atomic_dec_and_test(&msg->refcnt))
 152                 sctp_datamsg_destroy(msg);
 153 }
 154
 155 /* Assign a chunk to this datamsg. */
 156 static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk)
 157 {
 158         sctp_datamsg_hold(msg);
 159         chunk->msg = msg;
 160 }
 161
 162
 163 /* A data chunk can have a maximum payload of (2^16 - 20).  Break
 164  * down any such message into smaller chunks.  Opportunistically, fragment
 165  * the chunks down to the current MTU constraints.  We may get refragmented
 166  * later if the PMTU changes, but it is _much better_ to fragment immediately
 167  * with a reasonable guess than always doing our fragmentation on the
 168  * soft-interrupt.
 169  */
 170 struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
 171                                             struct sctp_sndrcvinfo *sinfo,
 172                                             struct msghdr *msgh, int msg_len)
 173 {
 174         int max, whole, i, offset, over, err;
 175         int len, first_len;
 176         int max_data;
 177         struct sctp_chunk *chunk;
 178         struct sctp_datamsg *msg;
 179         struct list_head *pos, *temp;
 180         __u8 frag;
 181
 182         msg = sctp_datamsg_new(GFP_KERNEL);
 183         if (!msg)
 184                 return NULL;
 185
 186         /* Note: Calculate this outside of the loop, so that all fragments
 187          * have the same expiration.
 188          */
 189         if (sinfo->sinfo_timetolive) {
 190                 /* sinfo_timetolive is in milliseconds */
 191                 msg->expires_at = jiffies +
 192                                     msecs_to_jiffies(sinfo->sinfo_timetolive);
 193                 msg->can_abandon = 1;
 194                 SCTP_DEBUG_PRINTK("%s: msg:%p expires_at: %ld jiffies:%ld\n",
 195                                   __func__, msg, msg->expires_at, jiffies);
 196         }
 197
 198         /* This is the biggest possible DATA chunk that can fit into
 199          * the packet
 200          */
 201         max_data = asoc->pathmtu -
 202                 sctp_sk(asoc->base.sk)->pf->af->net_header_len -
 203                 sizeof(struct sctphdr) - sizeof(struct sctp_data_chunk);
 204
 205         max = asoc->frag_point;
 206         /* If the the peer requested that we authenticate DATA chunks
 207          * we need to accound for bundling of the AUTH chunks along with
 208          * DATA.
 209          */
 210         if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) {
 211                 struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc);
 212
 213                 if (hmac_desc)
 214                         max_data -= WORD_ROUND(sizeof(sctp_auth_chunk_t) +
 215                                             hmac_desc->hmac_len);
 216         }
 217
 218         /* Now, check if we need to reduce our max */
 219         if (max > max_data)
 220                 max = max_data;
 221
 222         whole = 0;
 223         first_len = max;
 224
 225         /* Check to see if we have a pending SACK and try to let it be bundled
 226          * with this message.  Do this if we don't have any data queued already.
 227          * To check that, look at out_qlen and retransmit list.
 228          * NOTE: we will not reduce to account for SACK, if the message would
 229          * not have been fragmented.
 230          */
 231         if (timer_pending(&asoc->timers[SCTP_EVENT_TIMEOUT_SACK]) &&
 232             asoc->outqueue.out_qlen == 0 &&
 233             list_empty(&asoc->outqueue.retransmit) &&
 234             msg_len > max)
 235                 max_data -= WORD_ROUND(sizeof(sctp_sack_chunk_t));
 236
 237         /* Encourage Cookie-ECHO bundling. */
 238         if (asoc->state < SCTP_STATE_COOKIE_ECHOED)
 239                 max_data -= SCTP_ARBITRARY_COOKIE_ECHO_LEN;
 240
 241         /* Now that we adjusted completely, reset first_len */
 242         if (first_len > max_data)
 243                 first_len = max_data;
 244
 245         /* Account for a different sized first fragment */
 246         if (msg_len >= first_len) {
 247                 msg_len -= first_len;
 248                 whole = 1;
 249                 msg->can_delay = 0;
 250         }
 251
 252         /* How many full sized?  How many bytes leftover? */
 253         whole += msg_len / max;
 254         over = msg_len % max;
 255         offset = 0;
 256
 257         if ((whole > 1) || (whole && over))
 258                 SCTP_INC_STATS_USER(SCTP_MIB_FRAGUSRMSGS);
 259
 260         /* Create chunks for all the full sized DATA chunks. */
 261         for (i=0, len=first_len; i < whole; i++) {
 262                 frag = SCTP_DATA_MIDDLE_FRAG;
 263
 264                 if (0 == i)
 265                         frag |= SCTP_DATA_FIRST_FRAG;
 266
 267                 if ((i == (whole - 1)) && !over) {
 268                         frag |= SCTP_DATA_LAST_FRAG;
 269
 270                         /* The application requests to set the I-bit of the
 271                          * last DATA chunk of a user message when providing
 272                          * the user message to the SCTP implementation.
 273                          */
 274                         if ((sinfo->sinfo_flags & SCTP_EOF) ||
 275                             (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
 276                                 frag |= SCTP_DATA_SACK_IMM;
 277                 }
 278
 279                 chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag, 0);
 280
 281                 if (!chunk)
 282                         goto errout;
 283                 err = sctp_user_addto_chunk(chunk, offset, len, msgh->msg_iov);
 284                 if (err < 0)
 285                         goto errout;
 286
 287                 offset += len;
 288
 289                 /* Put the chunk->skb back into the form expected by send.  */
 290                 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 291                            - (__u8 *)chunk->skb->data);
 292
 293                 sctp_datamsg_assign(msg, chunk);
 294                 list_add_tail(&chunk->frag_list, &msg->chunks);
 295
 296                 /* The first chunk, the first chunk was likely short
 297                  * to allow bundling, so reset to full size.
 298                  */
 299                 if (0 == i)
 300                         len = max;
 301         }
 302
 303         /* .. now the leftover bytes. */
 304         if (over) {
 305                 if (!whole)
 306                         frag = SCTP_DATA_NOT_FRAG;
 307                 else
 308                         frag = SCTP_DATA_LAST_FRAG;
 309
 310                 if ((sinfo->sinfo_flags & SCTP_EOF) ||
 311                     (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
 312                         frag |= SCTP_DATA_SACK_IMM;
 313
 314                 chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 0);
 315
 316                 if (!chunk)
 317                         goto errout;
 318
 319                 err = sctp_user_addto_chunk(chunk, offset, over,msgh->msg_iov);
 320
 321                 /* Put the chunk->skb back into the form expected by send.  */
 322                 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 323                            - (__u8 *)chunk->skb->data);
 324                 if (err < 0)
 325                         goto errout;
 326
 327                 sctp_datamsg_assign(msg, chunk);
 328                 list_add_tail(&chunk->frag_list, &msg->chunks);
 329         }
 330
 331         return msg;
 332
 333 errout:
 334         list_for_each_safe(pos, temp, &msg->chunks) {
 335                 list_del_init(pos);
 336                 chunk = list_entry(pos, struct sctp_chunk, frag_list);
 337                 sctp_chunk_free(chunk);
 338         }
 339         sctp_datamsg_put(msg);
 340         return NULL;
 341 }
 342
 343 /* Check whether this message has expired. */
 344 int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 345 {
 346         struct sctp_datamsg *msg = chunk->msg;
 347
 348         if (!msg->can_abandon)
 349                 return 0;
 350
 351         if (time_after(jiffies, msg->expires_at))
 352                 return 1;
 353
 354         return 0;
 355 }
 356
 357 /* This chunk (and consequently entire message) has failed in its sending. */
 358 void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
 359 {
 360         chunk->msg->send_failed = 1;
 361         chunk->msg->send_error = error;
 362 }