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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  41
  42#include <linux/types.h>
  43#include <linux/kernel.h>
  44#include <linux/net.h>
  45#include <linux/inet.h>
  46#include <linux/skbuff.h>
  47#include <linux/slab.h>
  48#include <net/sock.h>
  49#include <net/sctp/sctp.h>
  50#include <net/sctp/sm.h>
  51
  52/* This file is mostly in anticipation of future work, but initially
  53 * populate with fragment tracking for an outbound message.
  54 */
  55
  56/* Initialize datamsg from memory. */
  57static void sctp_datamsg_init(struct sctp_datamsg *msg)
  58{
  59        atomic_set(&msg->refcnt, 1);
  60        msg->send_failed = 0;
  61        msg->send_error = 0;
  62        msg->can_abandon = 0;
  63        msg->can_delay = 1;
  64        msg->expires_at = 0;
  65        INIT_LIST_HEAD(&msg->chunks);
  66}
  67
  68/* Allocate and initialize datamsg. */
  69SCTP_STATIC struct sctp_datamsg *sctp_datamsg_new(gfp_t gfp)
  70{
  71        struct sctp_datamsg *msg;
  72        msg = kmalloc(sizeof(struct sctp_datamsg), gfp);
  73        if (msg) {
  74                sctp_datamsg_init(msg);
  75                SCTP_DBG_OBJCNT_INC(datamsg);
  76        }
  77        return msg;
  78}
  79
  80void sctp_datamsg_free(struct sctp_datamsg *msg)
  81{
  82        struct sctp_chunk *chunk;
  83
  84        /* This doesn't have to be a _safe vairant because
  85         * sctp_chunk_free() only drops the refs.
  86         */
  87        list_for_each_entry(chunk, &msg->chunks, frag_list)
  88                sctp_chunk_free(chunk);
  89
  90        sctp_datamsg_put(msg);
  91}
  92
  93/* Final destructruction of datamsg memory. */
  94static void sctp_datamsg_destroy(struct sctp_datamsg *msg)
  95{
  96        struct list_head *pos, *temp;
  97        struct sctp_chunk *chunk;
  98        struct sctp_sock *sp;
  99        struct sctp_ulpevent *ev;
 100        struct sctp_association *asoc = NULL;
 101        int error = 0, notify;
 102
 103        /* If we failed, we may need to notify. */
 104        notify = msg->send_failed ? -1 : 0;
 105
 106        /* Release all references. */
 107        list_for_each_safe(pos, temp, &msg->chunks) {
 108                list_del_init(pos);
 109                chunk = list_entry(pos, struct sctp_chunk, frag_list);
 110                /* Check whether we _really_ need to notify. */
 111                if (notify < 0) {
 112                        asoc = chunk->asoc;
 113                        if (msg->send_error)
 114                                error = msg->send_error;
 115                        else
 116                                error = asoc->outqueue.error;
 117
 118                        sp = sctp_sk(asoc->base.sk);
 119                        notify = sctp_ulpevent_type_enabled(SCTP_SEND_FAILED,
 120                                                            &sp->subscribe);
 121                }
 122
 123                /* Generate a SEND FAILED event only if enabled. */
 124                if (notify > 0) {
 125                        int sent;
 126                        if (chunk->has_tsn)
 127                                sent = SCTP_DATA_SENT;
 128                        else
 129                                sent = SCTP_DATA_UNSENT;
 130
 131                        ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent,
 132                                                            error, GFP_ATOMIC);
 133                        if (ev)
 134                                sctp_ulpq_tail_event(&asoc->ulpq, ev);
 135                }
 136
 137                sctp_chunk_put(chunk);
 138        }
 139
 140        SCTP_DBG_OBJCNT_DEC(datamsg);
 141        kfree(msg);
 142}
 143
 144/* Hold a reference. */
 145static void sctp_datamsg_hold(struct sctp_datamsg *msg)
 146{
 147        atomic_inc(&msg->refcnt);
 148}
 149
 150/* Release a reference. */
 151void sctp_datamsg_put(struct sctp_datamsg *msg)
 152{
 153        if (atomic_dec_and_test(&msg->refcnt))
 154                sctp_datamsg_destroy(msg);
 155}
 156
 157/* Assign a chunk to this datamsg. */
 158static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk)
 159{
 160        sctp_datamsg_hold(msg);
 161        chunk->msg = msg;
 162}
 163
 164
 165/* A data chunk can have a maximum payload of (2^16 - 20).  Break
 166 * down any such message into smaller chunks.  Opportunistically, fragment
 167 * the chunks down to the current MTU constraints.  We may get refragmented
 168 * later if the PMTU changes, but it is _much better_ to fragment immediately
 169 * with a reasonable guess than always doing our fragmentation on the
 170 * soft-interrupt.
 171 */
 172struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
 173                                            struct sctp_sndrcvinfo *sinfo,
 174                                            struct msghdr *msgh, int msg_len)
 175{
 176        int max, whole, i, offset, over, err;
 177        int len, first_len;
 178        int max_data;
 179        struct sctp_chunk *chunk;
 180        struct sctp_datamsg *msg;
 181        struct list_head *pos, *temp;
 182        __u8 frag;
 183
 184        msg = sctp_datamsg_new(GFP_KERNEL);
 185        if (!msg)
 186                return NULL;
 187
 188        /* Note: Calculate this outside of the loop, so that all fragments
 189         * have the same expiration.
 190         */
 191        if (sinfo->sinfo_timetolive) {
 192                /* sinfo_timetolive is in milliseconds */
 193                msg->expires_at = jiffies +
 194                                    msecs_to_jiffies(sinfo->sinfo_timetolive);
 195                msg->can_abandon = 1;
 196                SCTP_DEBUG_PRINTK("%s: msg:%p expires_at: %ld jiffies:%ld\n",
 197                                  __func__, msg, msg->expires_at, jiffies);
 198        }
 199
 200        /* This is the biggest possible DATA chunk that can fit into
 201         * the packet
 202         */
 203        max_data = asoc->pathmtu -
 204                sctp_sk(asoc->base.sk)->pf->af->net_header_len -
 205                sizeof(struct sctphdr) - sizeof(struct sctp_data_chunk);
 206
 207        max = asoc->frag_point;
 208        /* If the the peer requested that we authenticate DATA chunks
 209         * we need to accound for bundling of the AUTH chunks along with
 210         * DATA.
 211         */
 212        if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) {
 213                struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc);
 214
 215                if (hmac_desc)
 216                        max_data -= WORD_ROUND(sizeof(sctp_auth_chunk_t) +
 217                                            hmac_desc->hmac_len);
 218        }
 219
 220        /* Now, check if we need to reduce our max */
 221        if (max > max_data)
 222                max = max_data;
 223
 224        whole = 0;
 225        first_len = max;
 226
 227        /* Check to see if we have a pending SACK and try to let it be bundled
 228         * with this message.  Do this if we don't have any data queued already.
 229         * To check that, look at out_qlen and retransmit list.
 230         * NOTE: we will not reduce to account for SACK, if the message would
 231         * not have been fragmented.
 232         */
 233        if (timer_pending(&asoc->timers[SCTP_EVENT_TIMEOUT_SACK]) &&
 234            asoc->outqueue.out_qlen == 0 &&
 235            list_empty(&asoc->outqueue.retransmit) &&
 236            msg_len > max)
 237                max_data -= WORD_ROUND(sizeof(sctp_sack_chunk_t));
 238
 239        /* Encourage Cookie-ECHO bundling. */
 240        if (asoc->state < SCTP_STATE_COOKIE_ECHOED)
 241                max_data -= SCTP_ARBITRARY_COOKIE_ECHO_LEN;
 242
 243        /* Now that we adjusted completely, reset first_len */
 244        if (first_len > max_data)
 245                first_len = max_data;
 246
 247        /* Account for a different sized first fragment */
 248        if (msg_len >= first_len) {
 249                msg_len -= first_len;
 250                whole = 1;
 251                msg->can_delay = 0;
 252        }
 253
 254        /* How many full sized?  How many bytes leftover? */
 255        whole += msg_len / max;
 256        over = msg_len % max;
 257        offset = 0;
 258
 259        if ((whole > 1) || (whole && over))
 260                SCTP_INC_STATS_USER(SCTP_MIB_FRAGUSRMSGS);
 261
 262        /* Create chunks for all the full sized DATA chunks. */
 263        for (i=0, len=first_len; i < whole; i++) {
 264                frag = SCTP_DATA_MIDDLE_FRAG;
 265
 266                if (0 == i)
 267                        frag |= SCTP_DATA_FIRST_FRAG;
 268
 269                if ((i == (whole - 1)) && !over) {
 270                        frag |= SCTP_DATA_LAST_FRAG;
 271
 272                        /* The application requests to set the I-bit of the
 273                         * last DATA chunk of a user message when providing
 274                         * the user message to the SCTP implementation.
 275                         */
 276                        if ((sinfo->sinfo_flags & SCTP_EOF) ||
 277                            (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
 278                                frag |= SCTP_DATA_SACK_IMM;
 279                }
 280
 281                chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag, 0);
 282
 283                if (!chunk)
 284                        goto errout;
 285                err = sctp_user_addto_chunk(chunk, offset, len, msgh->msg_iov);
 286                if (err < 0)
 287                        goto errout;
 288
 289                offset += len;
 290
 291                /* Put the chunk->skb back into the form expected by send.  */
 292                __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 293                           - (__u8 *)chunk->skb->data);
 294
 295                sctp_datamsg_assign(msg, chunk);
 296                list_add_tail(&chunk->frag_list, &msg->chunks);
 297
 298                /* The first chunk, the first chunk was likely short
 299                 * to allow bundling, so reset to full size.
 300                 */
 301                if (0 == i)
 302                        len = max;
 303        }
 304
 305        /* .. now the leftover bytes. */
 306        if (over) {
 307                if (!whole)
 308                        frag = SCTP_DATA_NOT_FRAG;
 309                else
 310                        frag = SCTP_DATA_LAST_FRAG;
 311
 312                if ((sinfo->sinfo_flags & SCTP_EOF) ||
 313                    (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
 314                        frag |= SCTP_DATA_SACK_IMM;
 315
 316                chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 0);
 317
 318                if (!chunk)
 319                        goto errout;
 320
 321                err = sctp_user_addto_chunk(chunk, offset, over,msgh->msg_iov);
 322
 323                /* Put the chunk->skb back into the form expected by send.  */
 324                __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 325                           - (__u8 *)chunk->skb->data);
 326                if (err < 0)
 327                        goto errout;
 328
 329                sctp_datamsg_assign(msg, chunk);
 330                list_add_tail(&chunk->frag_list, &msg->chunks);
 331        }
 332
 333        return msg;
 334
 335errout:
 336        list_for_each_safe(pos, temp, &msg->chunks) {
 337                list_del_init(pos);
 338                chunk = list_entry(pos, struct sctp_chunk, frag_list);
 339                sctp_chunk_free(chunk);
 340        }
 341        sctp_datamsg_put(msg);
 342        return NULL;
 343}
 344
 345/* Check whether this message has expired. */
 346int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 347{
 348        struct sctp_datamsg *msg = chunk->msg;
 349
 350        if (!msg->can_abandon)
 351                return 0;
 352
 353        if (time_after(jiffies, msg->expires_at))
 354                return 1;
 355
 356        return 0;
 357}
 358
 359/* This chunk (and consequently entire message) has failed in its sending. */
 360void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
 361{
 362        chunk->msg->send_failed = 1;
 363        chunk->msg->send_error = error;
 364}
 365
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