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 <net/sock.h>
  46 #include <net/sctp/sctp.h>
  47 #include <net/sctp/sm.h>
  48
  49 /* This file is mostly in anticipation of future work, but initially
  50  * populate with fragment tracking for an outbound message.
  51  */
  52
  53 /* Initialize datamsg from memory. */
  54 static void sctp_datamsg_init(struct sctp_datamsg *msg)
  55 {
  56         atomic_set(&msg->refcnt, 1);
  57         msg->send_failed = 0;
  58         msg->send_error = 0;
  59         msg->can_abandon = 0;
  60         msg->expires_at = 0;
  61         INIT_LIST_HEAD(&msg->chunks);
  62         msg->msg_size = 0;
  63 }
  64
  65 /* Allocate and initialize datamsg. */
  66 SCTP_STATIC struct sctp_datamsg *sctp_datamsg_new(gfp_t gfp)
  67 {
  68         struct sctp_datamsg *msg;
  69         msg = kmalloc(sizeof(struct sctp_datamsg), gfp);
  70         if (msg) {
  71                 sctp_datamsg_init(msg);
  72                 SCTP_DBG_OBJCNT_INC(datamsg);
  73         }
  74         return msg;
  75 }
  76
  77 void sctp_datamsg_free(struct sctp_datamsg *msg)
  78 {
  79         struct sctp_chunk *chunk;
  80
  81         /* This doesn't have to be a _safe vairant because
  82          * sctp_chunk_free() only drops the refs.
  83          */
  84         list_for_each_entry(chunk, &msg->chunks, frag_list)
  85                 sctp_chunk_free(chunk);
  86
  87         sctp_datamsg_put(msg);
  88 }
  89
  90 /* Final destructruction of datamsg memory. */
  91 static void sctp_datamsg_destroy(struct sctp_datamsg *msg)
  92 {
  93         struct list_head *pos, *temp;
  94         struct sctp_chunk *chunk;
  95         struct sctp_sock *sp;
  96         struct sctp_ulpevent *ev;
  97         struct sctp_association *asoc = NULL;
  98         int error = 0, notify;
  99
 100         /* If we failed, we may need to notify. */
 101         notify = msg->send_failed ? -1 : 0;
 102
 103         /* Release all references. */
 104         list_for_each_safe(pos, temp, &msg->chunks) {
 105                 list_del_init(pos);
 106                 chunk = list_entry(pos, struct sctp_chunk, frag_list);
 107                 /* Check whether we _really_ need to notify. */
 108                 if (notify < 0) {
 109                         asoc = chunk->asoc;
 110                         if (msg->send_error)
 111                                 error = msg->send_error;
 112                         else
 113                                 error = asoc->outqueue.error;
 114
 115                         sp = sctp_sk(asoc->base.sk);
 116                         notify = sctp_ulpevent_type_enabled(SCTP_SEND_FAILED,
 117                                                             &sp->subscribe);
 118                 }
 119
 120                 /* Generate a SEND FAILED event only if enabled. */
 121                 if (notify > 0) {
 122                         int sent;
 123                         if (chunk->has_tsn)
 124                                 sent = SCTP_DATA_SENT;
 125                         else
 126                                 sent = SCTP_DATA_UNSENT;
 127
 128                         ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent,
 129                                                             error, GFP_ATOMIC);
 130                         if (ev)
 131                                 sctp_ulpq_tail_event(&asoc->ulpq, ev);
 132                 }
 133
 134                 sctp_chunk_put(chunk);
 135         }
 136
 137         SCTP_DBG_OBJCNT_DEC(datamsg);
 138         kfree(msg);
 139 }
 140
 141 /* Hold a reference. */
 142 static void sctp_datamsg_hold(struct sctp_datamsg *msg)
 143 {
 144         atomic_inc(&msg->refcnt);
 145 }
 146
 147 /* Release a reference. */
 148 void sctp_datamsg_put(struct sctp_datamsg *msg)
 149 {
 150         if (atomic_dec_and_test(&msg->refcnt))
 151                 sctp_datamsg_destroy(msg);
 152 }
 153
 154 /* Assign a chunk to this datamsg. */
 155 static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk)
 156 {
 157         sctp_datamsg_hold(msg);
 158         chunk->msg = msg;
 159         msg->msg_size += chunk->skb->len;
 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         }
 250
 251         /* How many full sized?  How many bytes leftover? */
 252         whole += msg_len / max;
 253         over = msg_len % max;
 254         offset = 0;
 255
 256         if ((whole > 1) || (whole && over))
 257                 SCTP_INC_STATS_USER(SCTP_MIB_FRAGUSRMSGS);
 258
 259         /* Create chunks for all the full sized DATA chunks. */
 260         for (i=0, len=first_len; i < whole; i++) {
 261                 frag = SCTP_DATA_MIDDLE_FRAG;
 262
 263                 if (0 == i)
 264                         frag |= SCTP_DATA_FIRST_FRAG;
 265
 266                 if ((i == (whole - 1)) && !over)
 267                         frag |= SCTP_DATA_LAST_FRAG;
 268
 269                 chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag, 0);
 270
 271                 if (!chunk)
 272                         goto errout;
 273                 err = sctp_user_addto_chunk(chunk, offset, len, msgh->msg_iov);
 274                 if (err < 0)
 275                         goto errout;
 276
 277                 offset += len;
 278
 279                 /* Put the chunk->skb back into the form expected by send.  */
 280                 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 281                            - (__u8 *)chunk->skb->data);
 282
 283                 sctp_datamsg_assign(msg, chunk);
 284                 list_add_tail(&chunk->frag_list, &msg->chunks);
 285
 286                 /* The first chunk, the first chunk was likely short
 287                  * to allow bundling, so reset to full size.
 288                  */
 289                 if (0 == i)
 290                         len = max;
 291         }
 292
 293         /* .. now the leftover bytes. */
 294         if (over) {
 295                 if (!whole)
 296                         frag = SCTP_DATA_NOT_FRAG;
 297                 else
 298                         frag = SCTP_DATA_LAST_FRAG;
 299
 300                 chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 0);
 301
 302                 if (!chunk)
 303                         goto errout;
 304
 305                 err = sctp_user_addto_chunk(chunk, offset, over,msgh->msg_iov);
 306
 307                 /* Put the chunk->skb back into the form expected by send.  */
 308                 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 309                            - (__u8 *)chunk->skb->data);
 310                 if (err < 0)
 311                         goto errout;
 312
 313                 sctp_datamsg_assign(msg, chunk);
 314                 list_add_tail(&chunk->frag_list, &msg->chunks);
 315         }
 316
 317         return msg;
 318
 319 errout:
 320         list_for_each_safe(pos, temp, &msg->chunks) {
 321                 list_del_init(pos);
 322                 chunk = list_entry(pos, struct sctp_chunk, frag_list);
 323                 sctp_chunk_free(chunk);
 324         }
 325         sctp_datamsg_put(msg);
 326         return NULL;
 327 }
 328
 329 /* Check whether this message has expired. */
 330 int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 331 {
 332         struct sctp_datamsg *msg = chunk->msg;
 333
 334         if (!msg->can_abandon)
 335                 return 0;
 336
 337         if (time_after(jiffies, msg->expires_at))
 338                 return 1;
 339
 340         return 0;
 341 }
 342
 343 /* This chunk (and consequently entire message) has failed in its sending. */
 344 void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
 345 {
 346         chunk->msg->send_failed = 1;
 347         chunk->msg->send_error = error;
 348 }