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/* SCTP kernel reference Implementation

 * Copyright (c) 2003 International Business Machines Corp.

 *

 * This file is part of the SCTP kernel reference Implementation

 *

 * This file contains the code relating the the chunk abstraction.

 *

 * The SCTP reference implementation is free software;

 * you can redistribute it and/or modify it under the terms of

 * the GNU General Public License as published by

 * the Free Software Foundation; either version 2, or (at your option)

 * any later version.

 *

 * The SCTP reference implementation is distributed in the hope that it

 * will be useful, but WITHOUT ANY WARRANTY; without even the implied

 *                 ************************

 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

 * See the GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with GNU CC; see the file COPYING.  If not, write to

 * the Free Software Foundation, 59 Temple Place - Suite 330,

 * Boston, MA 02111-1307, USA.

 *

 * Please send any bug reports or fixes you make to the

 * email address(es):

 *    lksctp developers <lksctp-developers@lists.sourceforge.net>

 *

 * Or submit a bug report through the following website:

 *    http://www.sf.net/projects/lksctp

 *

 * Written or modified by:

 *    Jon Grimm             <jgrimm@us.ibm.com>

 *

 * Any bugs reported given to us we will try to fix... any fixes shared will

 * be incorporated into the next SCTP release.

 */

#include <linux/types.h>

#include <linux/kernel.h>

#include <linux/net.h>

#include <linux/inet.h>

#include <linux/skbuff.h>

#include <net/sock.h>

#include <net/sctp/sctp.h>

#include <net/sctp/sm.h>

/* This file is mostly in anticipation of future work, but initially

 * populate with fragment tracking for an outbound message.

 */

/* Initialize datamsg from memory. */

void sctp_datamsg_init(struct sctp_datamsg *msg)

{

        atomic_set(&msg->refcnt, 1);

        msg->send_failed = 0;

        msg->send_error = 0;

        msg->can_expire = 0;

        INIT_LIST_HEAD(&msg->chunks);

}

/* Allocate and initialize datamsg. */

struct sctp_datamsg *sctp_datamsg_new(int gfp)

{

        struct sctp_datamsg *msg;

        msg = kmalloc(sizeof(struct sctp_datamsg), gfp);

        if (msg)

                sctp_datamsg_init(msg);

        SCTP_DBG_OBJCNT_INC(datamsg);

        return msg;

}

/* Final destructruction of datamsg memory. */

static void sctp_datamsg_destroy(struct sctp_datamsg *msg)

{

        struct list_head *pos, *temp;

        struct sctp_chunk *chunk;

        struct sctp_opt *sp;

        struct sctp_ulpevent *ev;

        struct sctp_association *asoc = NULL;

        int error = 0, notify;

        /* If we failed, we may need to notify. */

        notify = msg->send_failed ? -1 : 0;

        /* Release all references. */

        list_for_each_safe(pos, temp, &msg->chunks) {

                list_del_init(pos);

                chunk = list_entry(pos, struct sctp_chunk, frag_list);

                /* Check whether we _really_ need to notify. */

                if (notify < 0) {

                        asoc = chunk->asoc;

                        if (msg->send_error)

                                error = msg->send_error;

                        else

                                error = asoc->outqueue.error;

                        sp = sctp_sk(asoc->base.sk);

                        notify = sctp_ulpevent_type_enabled(SCTP_SEND_FAILED,

                                                            &sp->subscribe);

                }

                /* Generate a SEND FAILED event only if enabled. */

                if (notify > 0) {

                        int sent;

                        if (chunk->has_tsn)

                                sent = SCTP_DATA_SENT;

                        else

                                sent = SCTP_DATA_UNSENT;

                        ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent,

                                                            error, GFP_ATOMIC);

                        if (ev)

                                sctp_ulpq_tail_event(&asoc->ulpq, ev);

                }

                sctp_chunk_put(chunk);

        }

        SCTP_DBG_OBJCNT_DEC(datamsg);

        kfree(msg);

}

/* Hold a reference. */

void sctp_datamsg_hold(struct sctp_datamsg *msg)

{

        atomic_inc(&msg->refcnt);

}

/* Release a reference. */

void sctp_datamsg_put(struct sctp_datamsg *msg)

{

        if (atomic_dec_and_test(&msg->refcnt))

                sctp_datamsg_destroy(msg);

}

/* Free a message.  Really just give up a reference, the

 * really free happens in sctp_datamsg_destroy().

 */

void sctp_datamsg_free(struct sctp_datamsg *msg)

{

        sctp_datamsg_put(msg);

}

/* Hold on to all the fragments until all chunks have been sent. */

void sctp_datamsg_track(struct sctp_chunk *chunk)

{

        sctp_chunk_hold(chunk);

}

/* Assign a chunk to this datamsg. */

void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk)

{

        sctp_datamsg_hold(msg);

        chunk->msg = msg;

}

/* A data chunk can have a maximum payload of (2^16 - 20).  Break

 * down any such message into smaller chunks.  Opportunistically, fragment

 * the chunks down to the current MTU constraints.  We may get refragmented

 * later if the PMTU changes, but it is _much better_ to fragment immediately

 * with a reasonable guess than always doing our fragmentation on the

 * soft-interrupt.

 */

struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,

                                            struct sctp_sndrcvinfo *sinfo,

                                            struct msghdr *msgh, int msg_len)

{

        int max, whole, i, offset, over, err;

        int len, first_len;

        struct sctp_chunk *chunk;

        struct sctp_datamsg *msg;

        struct list_head *pos, *temp;

        __u8 frag;

        msg = sctp_datamsg_new(GFP_KERNEL);

        if (!msg)

                return NULL;

        /* Note: Calculate this outside of the loop, so that all fragments

         * have the same expiration.

         */

        if (sinfo->sinfo_timetolive) {

                /* sinfo_timetolive is in milliseconds */

                msg->expires_at = jiffies +

                                     SCTP_MSECS_TO_JIFFIES(sinfo->sinfo_timetolive);

                msg->can_expire = 1;

        }

        /* What is a reasonable fragmentation point right now? */

        max = asoc->pmtu;

        if (max < SCTP_MIN_PMTU)

                max = SCTP_MIN_PMTU;

        max -= SCTP_IP_OVERHEAD;

        /* Make sure not beyond maximum chunk size. */

        if (max > SCTP_MAX_CHUNK_LEN)

                max = SCTP_MAX_CHUNK_LEN;

        /* Subtract out the overhead of a data chunk header. */

        max -= sizeof(struct sctp_data_chunk);

        whole = 0;

        /* If user has specified smaller fragmentation, make it so. */

        if (sctp_sk(asoc->base.sk)->user_frag)

                max = min_t(int, max, sctp_sk(asoc->base.sk)->user_frag);

        first_len = max;

        /* Encourage Cookie-ECHO bundling. */

        if (asoc->state < SCTP_STATE_COOKIE_ECHOED) {

                whole = msg_len / (max - SCTP_ARBITRARY_COOKIE_ECHO_LEN);

                /* Account for the DATA to be bundled with the COOKIE-ECHO. */

                if (whole) {

                        first_len = max - SCTP_ARBITRARY_COOKIE_ECHO_LEN;

                        msg_len -= first_len;

                        whole = 1;

                }

        }

        /* How many full sized?  How many bytes leftover? */

        whole += msg_len / max;

        over = msg_len % max;

        offset = 0;

        if ((whole > 1) || (whole && over))

                SCTP_INC_STATS_USER(SctpFragUsrMsgs);

        /* Create chunks for all the full sized DATA chunks. */

        for (i=0, len=first_len; i < whole; i++) {

                frag = SCTP_DATA_MIDDLE_FRAG;

                if (0 == i)

                        frag |= SCTP_DATA_FIRST_FRAG;

                if ((i == (whole - 1)) && !over)

                        frag |= SCTP_DATA_LAST_FRAG;

                chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag, 0);

                if (!chunk)

                        goto errout;

                err = sctp_user_addto_chunk(chunk, offset, len, msgh->msg_iov);

                if (err < 0)

                        goto errout;

                offset += len;

                /* Put the chunk->skb back into the form expected by send.  */

                __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr

                           - (__u8 *)chunk->skb->data);

                sctp_datamsg_assign(msg, chunk);

                list_add_tail(&chunk->frag_list, &msg->chunks);

                /* The first chunk, the first chunk was likely short

                 * to allow bundling, so reset to full size.

                 */

                if (0 == i)

                        len = max;

        }

        /* .. now the leftover bytes. */

        if (over) {

                if (!whole)

                        frag = SCTP_DATA_NOT_FRAG;

                else

                        frag = SCTP_DATA_LAST_FRAG;

                chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 0);

                if (!chunk)

                        goto errout;

                err = sctp_user_addto_chunk(chunk, offset, over,msgh->msg_iov);

                /* Put the chunk->skb back into the form expected by send.  */

                __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr

                           - (__u8 *)chunk->skb->data);

                if (err < 0)

                        goto errout;

                sctp_datamsg_assign(msg, chunk);

                list_add_tail(&chunk->frag_list, &msg->chunks);

        }

        return msg;

errout:

        list_for_each_safe(pos, temp, &msg->chunks) {

                list_del_init(pos);

                chunk = list_entry(pos, struct sctp_chunk, frag_list);

                sctp_chunk_free(chunk);

        }

        sctp_datamsg_free(msg);

        return NULL;

}

/* Check whether this message has expired. */

int sctp_datamsg_expires(struct sctp_chunk *chunk)

{

        struct sctp_datamsg *msg = chunk->msg;

        /* FIXME: When PR-SCTP is supported we can make this

         * check more lenient.

         */

        if (!msg->can_expire)

                return 0;

        if (time_after(jiffies, msg->expires_at))

                return 1;

        return 0;

}

/* This chunk (and consequently entire message) has failed in its sending. */

void sctp_datamsg_fail(struct sctp_chunk *chunk, int error)

{

        chunk->msg->send_failed = 1;

        chunk->msg->send_error = error;

}