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 }
  63
  64 /* Allocate and initialize datamsg. */
  65 SCTP_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. */
  77 static 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. */
 128 static void sctp_datamsg_hold(struct sctp_datamsg *msg)
 129 {
 130         atomic_inc(&msg->refcnt);
 131 }
 132
 133 /* Release a reference. */
 134 void 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. */
 141 static 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  */
 155 struct 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
 279 errout:
 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. */
 290 int 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. */
 304 void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
 305 {
 306         chunk->msg->send_failed = 1;
 307         chunk->msg->send_error = error;
 308 }