net/sctp/chunk.c

   1 /* SCTP kernel reference Implementation
   2  * (C) Copyright IBM Corp. 2003, 2004
   3  *
   4  * This file is part of the SCTP kernel reference Implementation
   5  *
   6  * This file contains the code relating the the chunk abstraction.
   7  *
   8  * The SCTP reference 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  * The SCTP reference 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 }
  63
  64 /* Allocate and initialize datamsg. */
  65 SCTP_STATIC struct sctp_datamsg *sctp_datamsg_new(int 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         return msg;
  73 }
  74
  75 /* Final destructruction of datamsg memory. */
  76 static void sctp_datamsg_destroy(struct sctp_datamsg *msg)
  77 {
  78         struct list_head *pos, *temp;
  79         struct sctp_chunk *chunk;
  80         struct sctp_sock *sp;
  81         struct sctp_ulpevent *ev;
  82         struct sctp_association *asoc = NULL;
  83         int error = 0, notify;
  84
  85         /* If we failed, we may need to notify. */
  86         notify = msg->send_failed ? -1 : 0;
  87
  88         /* Release all references. */
  89         list_for_each_safe(pos, temp, &msg->chunks) {
  90                 list_del_init(pos);
  91                 chunk = list_entry(pos, struct sctp_chunk, frag_list);
  92                 /* Check whether we _really_ need to notify. */
  93                 if (notify < 0) {
  94                         asoc = chunk->asoc;
  95                         if (msg->send_error)
  96                                 error = msg->send_error;
  97                         else
  98                                 error = asoc->outqueue.error;
  99
 100                         sp = sctp_sk(asoc->base.sk);
 101                         notify = sctp_ulpevent_type_enabled(SCTP_SEND_FAILED,
 102                                                             &sp->subscribe);
 103                 }
 104
 105                 /* Generate a SEND FAILED event only if enabled. */
 106                 if (notify > 0) {
 107                         int sent;
 108                         if (chunk->has_tsn)
 109                                 sent = SCTP_DATA_SENT;
 110                         else
 111                                 sent = SCTP_DATA_UNSENT;
 112
 113                         ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent,
 114                                                             error, GFP_ATOMIC);
 115                         if (ev)
 116                                 sctp_ulpq_tail_event(&asoc->ulpq, ev);
 117                 }
 118
 119                 sctp_chunk_put(chunk);
 120         }
 121
 122         SCTP_DBG_OBJCNT_DEC(datamsg);
 123         kfree(msg);
 124 }
 125
 126 /* Hold a reference. */
 127 static void sctp_datamsg_hold(struct sctp_datamsg *msg)
 128 {
 129         atomic_inc(&msg->refcnt);
 130 }
 131
 132 /* Release a reference. */
 133 void sctp_datamsg_put(struct sctp_datamsg *msg)
 134 {
 135         if (atomic_dec_and_test(&msg->refcnt))
 136                 sctp_datamsg_destroy(msg);
 137 }
 138
 139 /* Free a message.  Really just give up a reference, the
 140  * really free happens in sctp_datamsg_destroy().
 141  */
 142 void sctp_datamsg_free(struct sctp_datamsg *msg)
 143 {
 144         sctp_datamsg_put(msg);
 145 }
 146
 147 /* Hold on to all the fragments until all chunks have been sent. */
 148 void sctp_datamsg_track(struct sctp_chunk *chunk)
 149 {
 150         sctp_chunk_hold(chunk);
 151 }
 152
 153 /* Assign a chunk to this datamsg. */
 154 static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk)
 155 {
 156         sctp_datamsg_hold(msg);
 157         chunk->msg = msg;
 158 }
 159
 160
 161 /* A data chunk can have a maximum payload of (2^16 - 20).  Break
 162  * down any such message into smaller chunks.  Opportunistically, fragment
 163  * the chunks down to the current MTU constraints.  We may get refragmented
 164  * later if the PMTU changes, but it is _much better_ to fragment immediately
 165  * with a reasonable guess than always doing our fragmentation on the
 166  * soft-interrupt.
 167  */
 168 struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
 169                                             struct sctp_sndrcvinfo *sinfo,
 170                                             struct msghdr *msgh, int msg_len)
 171 {
 172         int max, whole, i, offset, over, err;
 173         int len, first_len;
 174         struct sctp_chunk *chunk;
 175         struct sctp_datamsg *msg;
 176         struct list_head *pos, *temp;
 177         __u8 frag;
 178
 179         msg = sctp_datamsg_new(GFP_KERNEL);
 180         if (!msg)
 181                 return NULL;
 182
 183         /* Note: Calculate this outside of the loop, so that all fragments
 184          * have the same expiration.
 185          */
 186         if (sinfo->sinfo_timetolive) {
 187                 /* sinfo_timetolive is in milliseconds */
 188                 msg->expires_at = jiffies +
 189                                     msecs_to_jiffies(sinfo->sinfo_timetolive);
 190                 msg->can_abandon = 1;
 191                 SCTP_DEBUG_PRINTK("%s: msg:%p expires_at: %ld jiffies:%ld\n",
 192                                   __FUNCTION__, msg, msg->expires_at, jiffies);
 193         }
 194
 195         max = asoc->frag_point;
 196
 197         whole = 0;
 198         first_len = max;
 199
 200         /* Encourage Cookie-ECHO bundling. */
 201         if (asoc->state < SCTP_STATE_COOKIE_ECHOED) {
 202                 whole = msg_len / (max - SCTP_ARBITRARY_COOKIE_ECHO_LEN);
 203
 204                 /* Account for the DATA to be bundled with the COOKIE-ECHO. */
 205                 if (whole) {
 206                         first_len = max - SCTP_ARBITRARY_COOKIE_ECHO_LEN;
 207                         msg_len -= first_len;
 208                         whole = 1;
 209                 }
 210         }
 211
 212         /* How many full sized?  How many bytes leftover? */
 213         whole += msg_len / max;
 214         over = msg_len % max;
 215         offset = 0;
 216
 217         if ((whole > 1) || (whole && over))
 218                 SCTP_INC_STATS_USER(SCTP_MIB_FRAGUSRMSGS);
 219
 220         /* Create chunks for all the full sized DATA chunks. */
 221         for (i=0, len=first_len; i < whole; i++) {
 222                 frag = SCTP_DATA_MIDDLE_FRAG;
 223
 224                 if (0 == i)
 225                         frag |= SCTP_DATA_FIRST_FRAG;
 226
 227                 if ((i == (whole - 1)) && !over)
 228                         frag |= SCTP_DATA_LAST_FRAG;
 229
 230                 chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag, 0);
 231
 232                 if (!chunk)
 233                         goto errout;
 234                 err = sctp_user_addto_chunk(chunk, offset, len, msgh->msg_iov);
 235                 if (err < 0)
 236                         goto errout;
 237
 238                 offset += len;
 239
 240                 /* Put the chunk->skb back into the form expected by send.  */
 241                 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 242                            - (__u8 *)chunk->skb->data);
 243
 244                 sctp_datamsg_assign(msg, chunk);
 245                 list_add_tail(&chunk->frag_list, &msg->chunks);
 246
 247                 /* The first chunk, the first chunk was likely short
 248                  * to allow bundling, so reset to full size.
 249                  */
 250                 if (0 == i)
 251                         len = max;
 252         }
 253
 254         /* .. now the leftover bytes. */
 255         if (over) {
 256                 if (!whole)
 257                         frag = SCTP_DATA_NOT_FRAG;
 258                 else
 259                         frag = SCTP_DATA_LAST_FRAG;
 260
 261                 chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 0);
 262
 263                 if (!chunk)
 264                         goto errout;
 265
 266                 err = sctp_user_addto_chunk(chunk, offset, over,msgh->msg_iov);
 267
 268                 /* Put the chunk->skb back into the form expected by send.  */
 269                 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
 270                            - (__u8 *)chunk->skb->data);
 271                 if (err < 0)
 272                         goto errout;
 273
 274                 sctp_datamsg_assign(msg, chunk);
 275                 list_add_tail(&chunk->frag_list, &msg->chunks);
 276         }
 277
 278         return msg;
 279
 280 errout:
 281         list_for_each_safe(pos, temp, &msg->chunks) {
 282                 list_del_init(pos);
 283                 chunk = list_entry(pos, struct sctp_chunk, frag_list);
 284                 sctp_chunk_free(chunk);
 285         }
 286         sctp_datamsg_free(msg);
 287         return NULL;
 288 }
 289
 290 /* Check whether this message has expired. */
 291 int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 292 {
 293         struct sctp_datamsg *msg = chunk->msg;
 294
 295         if (!msg->can_abandon)
 296                 return 0;
 297
 298         if (time_after(jiffies, msg->expires_at))
 299                 return 1;
 300
 301         return 0;
 302 }
 303
 304 /* This chunk (and consequently entire message) has failed in its sending. */
 305 void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
 306 {
 307         chunk->msg->send_failed = 1;
 308         chunk->msg->send_error = error;
 309 }