linux/net/sctp/chunk.c
<<
>>
Prefs
   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. */
  54static 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}
  63
  64/* Allocate and initialize datamsg. */
  65SCTP_STATIC struct sctp_datamsg *sctp_datamsg_new(gfp_t gfp)
  66{
  67        struct sctp_datamsg *msg;
  68        msg = kmalloc(sizeof(struct sctp_datamsg), gfp);
  69        if (msg) {
  70                sctp_datamsg_init(msg);
  71                SCTP_DBG_OBJCNT_INC(datamsg);
  72        }
  73        return msg;
  74}
  75
  76/* Final destructruction of datamsg memory. */
  77static void sctp_datamsg_destroy(struct sctp_datamsg *msg)
  78{
  79        struct list_head *pos, *temp;
  80        struct sctp_chunk *chunk;
  81        struct sctp_sock *sp;
  82        struct sctp_ulpevent *ev;
  83        struct sctp_association *asoc = NULL;
  84        int error = 0, notify;
  85
  86        /* If we failed, we may need to notify. */
  87        notify = msg->send_failed ? -1 : 0;
  88
  89        /* Release all references. */
  90        list_for_each_safe(pos, temp, &msg->chunks) {
  91                list_del_init(pos);
  92                chunk = list_entry(pos, struct sctp_chunk, frag_list);
  93                /* Check whether we _really_ need to notify. */
  94                if (notify < 0) {
  95                        asoc = chunk->asoc;
  96                        if (msg->send_error)
  97                                error = msg->send_error;
  98                        else
  99                                error = asoc->outqueue.error;
 100
 101                        sp = sctp_sk(asoc->base.sk);
 102                        notify = sctp_ulpevent_type_enabled(SCTP_SEND_FAILED,
 103                                                            &sp->subscribe);
 104                }
 105
 106                /* Generate a SEND FAILED event only if enabled. */
 107                if (notify > 0) {
 108                        int sent;
 109                        if (chunk->has_tsn)
 110                                sent = SCTP_DATA_SENT;
 111                        else
 112                                sent = SCTP_DATA_UNSENT;
 113
 114                        ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent,
 115                                                            error, GFP_ATOMIC);
 116                        if (ev)
 117                                sctp_ulpq_tail_event(&asoc->ulpq, ev);
 118                }
 119
 120                sctp_chunk_put(chunk);
 121        }
 122
 123        SCTP_DBG_OBJCNT_DEC(datamsg);
 124        kfree(msg);
 125}
 126
 127/* Hold a reference. */
 128static void sctp_datamsg_hold(struct sctp_datamsg *msg)
 129{
 130        atomic_inc(&msg->refcnt);
 131}
 132
 133/* Release a reference. */
 134void sctp_datamsg_put(struct sctp_datamsg *msg)
 135{
 136        if (atomic_dec_and_test(&msg->refcnt))
 137                sctp_datamsg_destroy(msg);
 138}
 139
 140/* Assign a chunk to this datamsg. */
 141static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk)
 142{
 143        sctp_datamsg_hold(msg);
 144        chunk->msg = msg;
 145}
 146
 147
 148/* A data chunk can have a maximum payload of (2^16 - 20).  Break
 149 * down any such message into smaller chunks.  Opportunistically, fragment
 150 * the chunks down to the current MTU constraints.  We may get refragmented
 151 * later if the PMTU changes, but it is _much better_ to fragment immediately
 152 * with a reasonable guess than always doing our fragmentation on the
 153 * soft-interrupt.
 154 */
 155struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
 156                                            struct sctp_sndrcvinfo *sinfo,
 157                                            struct msghdr *msgh, int msg_len)
 158{
 159        int max, whole, i, offset, over, err;
 160        int len, first_len;
 161        struct sctp_chunk *chunk;
 162        struct sctp_datamsg *msg;
 163        struct list_head *pos, *temp;
 164        __u8 frag;
 165
 166        msg = sctp_datamsg_new(GFP_KERNEL);
 167        if (!msg)
 168                return NULL;
 169
 170        /* Note: Calculate this outside of the loop, so that all fragments
 171         * have the same expiration.
 172         */
 173        if (sinfo->sinfo_timetolive) {
 174                /* sinfo_timetolive is in milliseconds */
 175                msg->expires_at = jiffies +
 176                                    msecs_to_jiffies(sinfo->sinfo_timetolive);
 177                msg->can_abandon = 1;
 178                SCTP_DEBUG_PRINTK("%s: msg:%p expires_at: %ld jiffies:%ld\n",
 179                                  __func__, msg, msg->expires_at, jiffies);
 180        }
 181
 182        max = asoc->frag_point;
 183
 184        /* If the the peer requested that we authenticate DATA chunks
 185         * we need to accound for bundling of the AUTH chunks along with
 186         * DATA.
 187         */
 188        if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) {
 189                struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc);
 190
 191                if (hmac_desc)
 192                        max -= WORD_ROUND(sizeof(sctp_auth_chunk_t) +
 193                                            hmac_desc->hmac_len);
 194        }
 195
 196        whole = 0;
 197        first_len = max;
 198
 199        /* Encourage Cookie-ECHO bundling. */
 200        if (asoc->state < SCTP_STATE_COOKIE_ECHOED) {
 201                whole = msg_len / (max - SCTP_ARBITRARY_COOKIE_ECHO_LEN);
 202
 203                /* Account for the DATA to be bundled with the COOKIE-ECHO. */
 204                if (whole) {
 205                        first_len = max - SCTP_ARBITRARY_COOKIE_ECHO_LEN;
 206                        msg_len -= first_len;
 207                        whole = 1;
 208                }
 209        }
 210
 211        /* How many full sized?  How many bytes leftover? */
 212        whole += msg_len / max;
 213        over = msg_len % max;
 214        offset = 0;
 215
 216        if ((whole > 1) || (whole && over))
 217                SCTP_INC_STATS_USER(SCTP_MIB_FRAGUSRMSGS);
 218
 219        /* Create chunks for all the full sized DATA chunks. */
 220        for (i=0, len=first_len; i < whole; i++) {
 221                frag = SCTP_DATA_MIDDLE_FRAG;
 222
 223                if (0 == i)
 224                        frag |= SCTP_DATA_FIRST_FRAG;
 225
 226                if ((i == (whole - 1)) && !over)
 227                        frag |= SCTP_DATA_LAST_FRAG;
 228
 229                chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag, 0);
 230
 231                if (!chunk)
 232                        goto errout;
 233                err = sctp_user_addto_chunk(chunk, offset, len, msgh->msg_iov);
 234                if (err < 0)
 235                        goto errout;
 236
 237                offset += len;
 238
 239                /* Put the chunk->skb back into the form expected by send.  */
 240                __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 241                           - (__u8 *)chunk->skb->data);
 242
 243                sctp_datamsg_assign(msg, chunk);
 244                list_add_tail(&chunk->frag_list, &msg->chunks);
 245
 246                /* The first chunk, the first chunk was likely short
 247                 * to allow bundling, so reset to full size.
 248                 */
 249                if (0 == i)
 250                        len = max;
 251        }
 252
 253        /* .. now the leftover bytes. */
 254        if (over) {
 255                if (!whole)
 256                        frag = SCTP_DATA_NOT_FRAG;
 257                else
 258                        frag = SCTP_DATA_LAST_FRAG;
 259
 260                chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 0);
 261
 262                if (!chunk)
 263                        goto errout;
 264
 265                err = sctp_user_addto_chunk(chunk, offset, over,msgh->msg_iov);
 266
 267                /* Put the chunk->skb back into the form expected by send.  */
 268                __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 269                           - (__u8 *)chunk->skb->data);
 270                if (err < 0)
 271                        goto errout;
 272
 273                sctp_datamsg_assign(msg, chunk);
 274                list_add_tail(&chunk->frag_list, &msg->chunks);
 275        }
 276
 277        return msg;
 278
 279errout:
 280        list_for_each_safe(pos, temp, &msg->chunks) {
 281                list_del_init(pos);
 282                chunk = list_entry(pos, struct sctp_chunk, frag_list);
 283                sctp_chunk_free(chunk);
 284        }
 285        sctp_datamsg_put(msg);
 286        return NULL;
 287}
 288
 289/* Check whether this message has expired. */
 290int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 291{
 292        struct sctp_datamsg *msg = chunk->msg;
 293
 294        if (!msg->can_abandon)
 295                return 0;
 296
 297        if (time_after(jiffies, msg->expires_at))
 298                return 1;
 299
 300        return 0;
 301}
 302
 303/* This chunk (and consequently entire message) has failed in its sending. */
 304void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
 305{
 306        chunk->msg->send_failed = 1;
 307        chunk->msg->send_error = error;
 308}
 309