linux/net/sctp/chunk.c
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   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. */
  55static 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. */
  67SCTP_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
  78void 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. */
  92static 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. */
 143static void sctp_datamsg_hold(struct sctp_datamsg *msg)
 144{
 145        atomic_inc(&msg->refcnt);
 146}
 147
 148/* Release a reference. */
 149void 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. */
 156static 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 */
 170struct 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
 333errout:
 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. */
 344int 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. */
 358void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
 359{
 360        chunk->msg->send_failed = 1;
 361        chunk->msg->send_error = error;
 362}
 363