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ulpevent.c

/* SCTP kernel reference Implementation
 * (C) Copyright IBM Corp. 2001, 2004
 * Copyright (c) 1999-2000 Cisco, Inc.
 * Copyright (c) 1999-2001 Motorola, Inc.
 * Copyright (c) 2001 Intel Corp.
 * Copyright (c) 2001 Nokia, Inc.
 * Copyright (c) 2001 La Monte H.P. Yarroll
 *
 * These functions manipulate an sctp event.   The struct ulpevent is used
 * to carry notifications and data to the ULP (sockets).
 * 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>
 *    La Monte H.P. Yarroll <piggy@acm.org>
 *    Ardelle Fan     <ardelle.fan@intel.com>
 *    Sridhar Samudrala     <sri@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/skbuff.h>
#include <net/sctp/structs.h>
#include <net/sctp/sctp.h>
#include <net/sctp/sm.h>

static void sctp_ulpevent_receive_data(struct sctp_ulpevent *event,
                               struct sctp_association *asoc);
static void sctp_ulpevent_release_data(struct sctp_ulpevent *event);
static void sctp_ulpevent_release_frag_data(struct sctp_ulpevent *event);


/* Initialize an ULP event from an given skb.  */
SCTP_STATIC void sctp_ulpevent_init(struct sctp_ulpevent *event,
                            int msg_flags,
                            unsigned int len)
{
      memset(event, 0, sizeof(struct sctp_ulpevent));
      event->msg_flags = msg_flags;
      event->rmem_len = len;
}

/* Create a new sctp_ulpevent.  */
SCTP_STATIC struct sctp_ulpevent *sctp_ulpevent_new(int size, int msg_flags,
                                        gfp_t gfp)
{
      struct sctp_ulpevent *event;
      struct sk_buff *skb;

      skb = alloc_skb(size, gfp);
      if (!skb)
            goto fail;

      event = sctp_skb2event(skb);
      sctp_ulpevent_init(event, msg_flags, skb->truesize);

      return event;

fail:
      return NULL;
}

/* Is this a MSG_NOTIFICATION?  */
int sctp_ulpevent_is_notification(const struct sctp_ulpevent *event)
{
      return MSG_NOTIFICATION == (event->msg_flags & MSG_NOTIFICATION);
}

/* Hold the association in case the msg_name needs read out of
 * the association.
 */
static inline void sctp_ulpevent_set_owner(struct sctp_ulpevent *event,
                                 const struct sctp_association *asoc)
{
      struct sk_buff *skb;

      /* Cast away the const, as we are just wanting to
       * bump the reference count.
       */
      sctp_association_hold((struct sctp_association *)asoc);
      skb = sctp_event2skb(event);
      event->asoc = (struct sctp_association *)asoc;
      atomic_add(event->rmem_len, &event->asoc->rmem_alloc);
      sctp_skb_set_owner_r(skb, asoc->base.sk);
}

/* A simple destructor to give up the reference to the association. */
static inline void sctp_ulpevent_release_owner(struct sctp_ulpevent *event)
{
      struct sctp_association *asoc = event->asoc;

      atomic_sub(event->rmem_len, &asoc->rmem_alloc);
      sctp_association_put(asoc);
}

/* Create and initialize an SCTP_ASSOC_CHANGE event.
 *
 * 5.3.1.1 SCTP_ASSOC_CHANGE
 *
 * Communication notifications inform the ULP that an SCTP association
 * has either begun or ended. The identifier for a new association is
 * provided by this notification.
 *
 * Note: There is no field checking here.  If a field is unused it will be
 * zero'd out.
 */
struct sctp_ulpevent  *sctp_ulpevent_make_assoc_change(
      const struct sctp_association *asoc,
      __u16 flags, __u16 state, __u16 error, __u16 outbound,
      __u16 inbound, struct sctp_chunk *chunk, gfp_t gfp)
{
      struct sctp_ulpevent *event;
      struct sctp_assoc_change *sac;
      struct sk_buff *skb;

      /* If the lower layer passed in the chunk, it will be
       * an ABORT, so we need to include it in the sac_info.
       */
      if (chunk) {
            /* Copy the chunk data to a new skb and reserve enough
             * head room to use as notification.
             */
            skb = skb_copy_expand(chunk->skb,
                              sizeof(struct sctp_assoc_change), 0, gfp);

            if (!skb)
                  goto fail;

            /* Embed the event fields inside the cloned skb.  */
            event = sctp_skb2event(skb);
            sctp_ulpevent_init(event, MSG_NOTIFICATION, skb->truesize);

            /* Include the notification structure */
            sac = (struct sctp_assoc_change *)
                  skb_push(skb, sizeof(struct sctp_assoc_change));

            /* Trim the buffer to the right length.  */
            skb_trim(skb, sizeof(struct sctp_assoc_change) +
                   ntohs(chunk->chunk_hdr->length) -
                   sizeof(sctp_chunkhdr_t));
      } else {
            event = sctp_ulpevent_new(sizeof(struct sctp_assoc_change),
                          MSG_NOTIFICATION, gfp);
            if (!event)
                  goto fail;

            skb = sctp_event2skb(event);
            sac = (struct sctp_assoc_change *) skb_put(skb,
                              sizeof(struct sctp_assoc_change));
      }

      /* Socket Extensions for SCTP
       * 5.3.1.1 SCTP_ASSOC_CHANGE
       *
       * sac_type:
       * It should be SCTP_ASSOC_CHANGE.
       */
      sac->sac_type = SCTP_ASSOC_CHANGE;

      /* Socket Extensions for SCTP
       * 5.3.1.1 SCTP_ASSOC_CHANGE
       *
       * sac_state: 32 bits (signed integer)
       * This field holds one of a number of values that communicate the
       * event that happened to the association.
       */
      sac->sac_state = state;

      /* Socket Extensions for SCTP
       * 5.3.1.1 SCTP_ASSOC_CHANGE
       *
       * sac_flags: 16 bits (unsigned integer)
       * Currently unused.
       */
      sac->sac_flags = 0;

      /* Socket Extensions for SCTP
       * 5.3.1.1 SCTP_ASSOC_CHANGE
       *
       * sac_length: sizeof (__u32)
       * This field is the total length of the notification data, including
       * the notification header.
       */
      sac->sac_length = sizeof(struct sctp_assoc_change);

      /* Socket Extensions for SCTP
       * 5.3.1.1 SCTP_ASSOC_CHANGE
       *
       * sac_error:  32 bits (signed integer)
       *
       * If the state was reached due to a error condition (e.g.
       * COMMUNICATION_LOST) any relevant error information is available in
       * this field. This corresponds to the protocol error codes defined in
       * [SCTP].
       */
      sac->sac_error = error;

      /* Socket Extensions for SCTP
       * 5.3.1.1 SCTP_ASSOC_CHANGE
       *
       * sac_outbound_streams:  16 bits (unsigned integer)
       * sac_inbound_streams:  16 bits (unsigned integer)
       *
       * The maximum number of streams allowed in each direction are
       * available in sac_outbound_streams and sac_inbound streams.
       */
      sac->sac_outbound_streams = outbound;
      sac->sac_inbound_streams = inbound;

      /* Socket Extensions for SCTP
       * 5.3.1.1 SCTP_ASSOC_CHANGE
       *
       * sac_assoc_id: sizeof (sctp_assoc_t)
       *
       * The association id field, holds the identifier for the association.
       * All notifications for a given association have the same association
       * identifier.  For TCP style socket, this field is ignored.
       */
      sctp_ulpevent_set_owner(event, asoc);
      sac->sac_assoc_id = sctp_assoc2id(asoc);

      return event;

fail:
      return NULL;
}

/* Create and initialize an SCTP_PEER_ADDR_CHANGE event.
 *
 * Socket Extensions for SCTP - draft-01
 * 5.3.1.2 SCTP_PEER_ADDR_CHANGE
 *
 * When a destination address on a multi-homed peer encounters a change
 * an interface details event is sent.
 */
struct sctp_ulpevent *sctp_ulpevent_make_peer_addr_change(
      const struct sctp_association *asoc,
      const struct sockaddr_storage *aaddr,
      int flags, int state, int error, gfp_t gfp)
{
      struct sctp_ulpevent *event;
      struct sctp_paddr_change  *spc;
      struct sk_buff *skb;

      event = sctp_ulpevent_new(sizeof(struct sctp_paddr_change),
                          MSG_NOTIFICATION, gfp);
      if (!event)
            goto fail;

      skb = sctp_event2skb(event);
      spc = (struct sctp_paddr_change *)
            skb_put(skb, sizeof(struct sctp_paddr_change));

      /* Sockets API Extensions for SCTP
       * Section 5.3.1.2 SCTP_PEER_ADDR_CHANGE
       *
       * spc_type:
       *
       *    It should be SCTP_PEER_ADDR_CHANGE.
       */
      spc->spc_type = SCTP_PEER_ADDR_CHANGE;

      /* Sockets API Extensions for SCTP
       * Section 5.3.1.2 SCTP_PEER_ADDR_CHANGE
       *
       * spc_length: sizeof (__u32)
       *
       * This field is the total length of the notification data, including
       * the notification header.
       */
      spc->spc_length = sizeof(struct sctp_paddr_change);

      /* Sockets API Extensions for SCTP
       * Section 5.3.1.2 SCTP_PEER_ADDR_CHANGE
       *
       * spc_flags: 16 bits (unsigned integer)
       * Currently unused.
       */
      spc->spc_flags = 0;

      /* Sockets API Extensions for SCTP
       * Section 5.3.1.2 SCTP_PEER_ADDR_CHANGE
       *
       * spc_state:  32 bits (signed integer)
       *
       * This field holds one of a number of values that communicate the
       * event that happened to the address.
       */
      spc->spc_state = state;

      /* Sockets API Extensions for SCTP
       * Section 5.3.1.2 SCTP_PEER_ADDR_CHANGE
       *
       * spc_error:  32 bits (signed integer)
       *
       * If the state was reached due to any error condition (e.g.
       * ADDRESS_UNREACHABLE) any relevant error information is available in
       * this field.
       */
      spc->spc_error = error;

      /* Socket Extensions for SCTP
       * 5.3.1.1 SCTP_ASSOC_CHANGE
       *
       * spc_assoc_id: sizeof (sctp_assoc_t)
       *
       * The association id field, holds the identifier for the association.
       * All notifications for a given association have the same association
       * identifier.  For TCP style socket, this field is ignored.
       */
      sctp_ulpevent_set_owner(event, asoc);
      spc->spc_assoc_id = sctp_assoc2id(asoc);

      /* Sockets API Extensions for SCTP
       * Section 5.3.1.2 SCTP_PEER_ADDR_CHANGE
       *
       * spc_aaddr: sizeof (struct sockaddr_storage)
       *
       * The affected address field, holds the remote peer's address that is
       * encountering the change of state.
       */
      memcpy(&spc->spc_aaddr, aaddr, sizeof(struct sockaddr_storage));

      /* Map ipv4 address into v4-mapped-on-v6 address.  */
      sctp_get_pf_specific(asoc->base.sk->sk_family)->addr_v4map(
                              sctp_sk(asoc->base.sk),
                              (union sctp_addr *)&spc->spc_aaddr);

      return event;

fail:
      return NULL;
}

/* Create and initialize an SCTP_REMOTE_ERROR notification.
 *
 * Note: This assumes that the chunk->skb->data already points to the
 * operation error payload.
 *
 * Socket Extensions for SCTP - draft-01
 * 5.3.1.3 SCTP_REMOTE_ERROR
 *
 * A remote peer may send an Operational Error message to its peer.
 * This message indicates a variety of error conditions on an
 * association. The entire error TLV as it appears on the wire is
 * included in a SCTP_REMOTE_ERROR event.  Please refer to the SCTP
 * specification [SCTP] and any extensions for a list of possible
 * error formats.
 */
struct sctp_ulpevent *sctp_ulpevent_make_remote_error(
      const struct sctp_association *asoc, struct sctp_chunk *chunk,
      __u16 flags, gfp_t gfp)
{
      struct sctp_ulpevent *event;
      struct sctp_remote_error *sre;
      struct sk_buff *skb;
      sctp_errhdr_t *ch;
      __be16 cause;
      int elen;

      ch = (sctp_errhdr_t *)(chunk->skb->data);
      cause = ch->cause;
      elen = WORD_ROUND(ntohs(ch->length)) - sizeof(sctp_errhdr_t);

      /* Pull off the ERROR header.  */
      skb_pull(chunk->skb, sizeof(sctp_errhdr_t));

      /* Copy the skb to a new skb with room for us to prepend
       * notification with.
       */
      skb = skb_copy_expand(chunk->skb, sizeof(struct sctp_remote_error),
                        0, gfp);

      /* Pull off the rest of the cause TLV from the chunk.  */
      skb_pull(chunk->skb, elen);
      if (!skb)
            goto fail;

      /* Embed the event fields inside the cloned skb.  */
      event = sctp_skb2event(skb);
      sctp_ulpevent_init(event, MSG_NOTIFICATION, skb->truesize);

      sre = (struct sctp_remote_error *)
            skb_push(skb, sizeof(struct sctp_remote_error));

      /* Trim the buffer to the right length.  */
      skb_trim(skb, sizeof(struct sctp_remote_error) + elen);

      /* Socket Extensions for SCTP
       * 5.3.1.3 SCTP_REMOTE_ERROR
       *
       * sre_type:
       *   It should be SCTP_REMOTE_ERROR.
       */
      sre->sre_type = SCTP_REMOTE_ERROR;

      /*
       * Socket Extensions for SCTP
       * 5.3.1.3 SCTP_REMOTE_ERROR
       *
       * sre_flags: 16 bits (unsigned integer)
       *   Currently unused.
       */
      sre->sre_flags = 0;

      /* Socket Extensions for SCTP
       * 5.3.1.3 SCTP_REMOTE_ERROR
       *
       * sre_length: sizeof (__u32)
       *
       * This field is the total length of the notification data,
       * including the notification header.
       */
      sre->sre_length = skb->len;

      /* Socket Extensions for SCTP
       * 5.3.1.3 SCTP_REMOTE_ERROR
       *
       * sre_error: 16 bits (unsigned integer)
       * This value represents one of the Operational Error causes defined in
       * the SCTP specification, in network byte order.
       */
      sre->sre_error = cause;

      /* Socket Extensions for SCTP
       * 5.3.1.3 SCTP_REMOTE_ERROR
       *
       * sre_assoc_id: sizeof (sctp_assoc_t)
       *
       * The association id field, holds the identifier for the association.
       * All notifications for a given association have the same association
       * identifier.  For TCP style socket, this field is ignored.
       */
      sctp_ulpevent_set_owner(event, asoc);
      sre->sre_assoc_id = sctp_assoc2id(asoc);

      return event;

fail:
      return NULL;
}

/* Create and initialize a SCTP_SEND_FAILED notification.
 *
 * Socket Extensions for SCTP - draft-01
 * 5.3.1.4 SCTP_SEND_FAILED
 */
struct sctp_ulpevent *sctp_ulpevent_make_send_failed(
      const struct sctp_association *asoc, struct sctp_chunk *chunk,
      __u16 flags, __u32 error, gfp_t gfp)
{
      struct sctp_ulpevent *event;
      struct sctp_send_failed *ssf;
      struct sk_buff *skb;

      /* Pull off any padding. */
      int len = ntohs(chunk->chunk_hdr->length);

      /* Make skb with more room so we can prepend notification.  */
      skb = skb_copy_expand(chunk->skb,
                        sizeof(struct sctp_send_failed), /* headroom */
                        0,                               /* tailroom */
                        gfp);
      if (!skb)
            goto fail;

      /* Pull off the common chunk header and DATA header.  */
      skb_pull(skb, sizeof(struct sctp_data_chunk));
      len -= sizeof(struct sctp_data_chunk);

      /* Embed the event fields inside the cloned skb.  */
      event = sctp_skb2event(skb);
      sctp_ulpevent_init(event, MSG_NOTIFICATION, skb->truesize);

      ssf = (struct sctp_send_failed *)
            skb_push(skb, sizeof(struct sctp_send_failed));

      /* Socket Extensions for SCTP
       * 5.3.1.4 SCTP_SEND_FAILED
       *
       * ssf_type:
       * It should be SCTP_SEND_FAILED.
       */
      ssf->ssf_type = SCTP_SEND_FAILED;

      /* Socket Extensions for SCTP
       * 5.3.1.4 SCTP_SEND_FAILED
       *
       * ssf_flags: 16 bits (unsigned integer)
       * The flag value will take one of the following values
       *
       * SCTP_DATA_UNSENT - Indicates that the data was never put on
       *                    the wire.
       *
       * SCTP_DATA_SENT   - Indicates that the data was put on the wire.
       *                    Note that this does not necessarily mean that the
       *                    data was (or was not) successfully delivered.
       */
      ssf->ssf_flags = flags;

      /* Socket Extensions for SCTP
       * 5.3.1.4 SCTP_SEND_FAILED
       *
       * ssf_length: sizeof (__u32)
       * This field is the total length of the notification data, including
       * the notification header.
       */
      ssf->ssf_length = sizeof(struct sctp_send_failed) + len;
      skb_trim(skb, ssf->ssf_length);

      /* Socket Extensions for SCTP
       * 5.3.1.4 SCTP_SEND_FAILED
       *
       * ssf_error: 16 bits (unsigned integer)
       * This value represents the reason why the send failed, and if set,
       * will be a SCTP protocol error code as defined in [SCTP] section
       * 3.3.10.
       */
      ssf->ssf_error = error;

      /* Socket Extensions for SCTP
       * 5.3.1.4 SCTP_SEND_FAILED
       *
       * ssf_info: sizeof (struct sctp_sndrcvinfo)
       * The original send information associated with the undelivered
       * message.
       */
      memcpy(&ssf->ssf_info, &chunk->sinfo, sizeof(struct sctp_sndrcvinfo));

      /* Per TSVWG discussion with Randy. Allow the application to
       * ressemble a fragmented message.
       */
      ssf->ssf_info.sinfo_flags = chunk->chunk_hdr->flags;

      /* Socket Extensions for SCTP
       * 5.3.1.4 SCTP_SEND_FAILED
       *
       * ssf_assoc_id: sizeof (sctp_assoc_t)
       * The association id field, sf_assoc_id, holds the identifier for the
       * association.  All notifications for a given association have the
       * same association identifier.  For TCP style socket, this field is
       * ignored.
       */
      sctp_ulpevent_set_owner(event, asoc);
      ssf->ssf_assoc_id = sctp_assoc2id(asoc);
      return event;

fail:
      return NULL;
}

/* Create and initialize a SCTP_SHUTDOWN_EVENT notification.
 *
 * Socket Extensions for SCTP - draft-01
 * 5.3.1.5 SCTP_SHUTDOWN_EVENT
 */
struct sctp_ulpevent *sctp_ulpevent_make_shutdown_event(
      const struct sctp_association *asoc,
      __u16 flags, gfp_t gfp)
{
      struct sctp_ulpevent *event;
      struct sctp_shutdown_event *sse;
      struct sk_buff *skb;

      event = sctp_ulpevent_new(sizeof(struct sctp_shutdown_event),
                          MSG_NOTIFICATION, gfp);
      if (!event)
            goto fail;

      skb = sctp_event2skb(event);
      sse = (struct sctp_shutdown_event *)
            skb_put(skb, sizeof(struct sctp_shutdown_event));

      /* Socket Extensions for SCTP
       * 5.3.1.5 SCTP_SHUTDOWN_EVENT
       *
       * sse_type
       * It should be SCTP_SHUTDOWN_EVENT
       */
      sse->sse_type = SCTP_SHUTDOWN_EVENT;

      /* Socket Extensions for SCTP
       * 5.3.1.5 SCTP_SHUTDOWN_EVENT
       *
       * sse_flags: 16 bits (unsigned integer)
       * Currently unused.
       */
      sse->sse_flags = 0;

      /* Socket Extensions for SCTP
       * 5.3.1.5 SCTP_SHUTDOWN_EVENT
       *
       * sse_length: sizeof (__u32)
       * This field is the total length of the notification data, including
       * the notification header.
       */
      sse->sse_length = sizeof(struct sctp_shutdown_event);

      /* Socket Extensions for SCTP
       * 5.3.1.5 SCTP_SHUTDOWN_EVENT
       *
       * sse_assoc_id: sizeof (sctp_assoc_t)
       * The association id field, holds the identifier for the association.
       * All notifications for a given association have the same association
       * identifier.  For TCP style socket, this field is ignored.
       */
      sctp_ulpevent_set_owner(event, asoc);
      sse->sse_assoc_id = sctp_assoc2id(asoc);

      return event;

fail:
      return NULL;
}

/* Create and initialize a SCTP_ADAPTATION_INDICATION notification.
 *
 * Socket Extensions for SCTP
 * 5.3.1.6 SCTP_ADAPTATION_INDICATION
 */
struct sctp_ulpevent *sctp_ulpevent_make_adaptation_indication(
      const struct sctp_association *asoc, gfp_t gfp)
{
      struct sctp_ulpevent *event;
      struct sctp_adaptation_event *sai;
      struct sk_buff *skb;

      event = sctp_ulpevent_new(sizeof(struct sctp_adaptation_event),
                          MSG_NOTIFICATION, gfp);
      if (!event)
            goto fail;

      skb = sctp_event2skb(event);
      sai = (struct sctp_adaptation_event *)
            skb_put(skb, sizeof(struct sctp_adaptation_event));

      sai->sai_type = SCTP_ADAPTATION_INDICATION;
      sai->sai_flags = 0;
      sai->sai_length = sizeof(struct sctp_adaptation_event);
      sai->sai_adaptation_ind = asoc->peer.adaptation_ind;
      sctp_ulpevent_set_owner(event, asoc);
      sai->sai_assoc_id = sctp_assoc2id(asoc);

      return event;

fail:
      return NULL;
}

/* A message has been received.  Package this message as a notification
 * to pass it to the upper layers.  Go ahead and calculate the sndrcvinfo
 * even if filtered out later.
 *
 * Socket Extensions for SCTP
 * 5.2.2 SCTP Header Information Structure (SCTP_SNDRCV)
 */
struct sctp_ulpevent *sctp_ulpevent_make_rcvmsg(struct sctp_association *asoc,
                                    struct sctp_chunk *chunk,
                                    gfp_t gfp)
{
      struct sctp_ulpevent *event = NULL;
      struct sk_buff *skb;
      size_t padding, len;
      int rx_count;

      /*
       * check to see if we need to make space for this
       * new skb, expand the rcvbuffer if needed, or drop
       * the frame
       */
      if (asoc->ep->rcvbuf_policy)
            rx_count = atomic_read(&asoc->rmem_alloc);
      else
            rx_count = atomic_read(&asoc->base.sk->sk_rmem_alloc);

      if (rx_count >= asoc->base.sk->sk_rcvbuf) {

            if ((asoc->base.sk->sk_userlocks & SOCK_RCVBUF_LOCK) ||
               (!sk_stream_rmem_schedule(asoc->base.sk, chunk->skb)))
                  goto fail;
      }

      /* Clone the original skb, sharing the data.  */
      skb = skb_clone(chunk->skb, gfp);
      if (!skb)
            goto fail;

      /* First calculate the padding, so we don't inadvertently
       * pass up the wrong length to the user.
       *
       * RFC 2960 - Section 3.2  Chunk Field Descriptions
       *
       * The total length of a chunk(including Type, Length and Value fields)
       * MUST be a multiple of 4 bytes.  If the length of the chunk is not a
       * multiple of 4 bytes, the sender MUST pad the chunk with all zero
       * bytes and this padding is not included in the chunk length field.
       * The sender should never pad with more than 3 bytes.  The receiver
       * MUST ignore the padding bytes.
       */
      len = ntohs(chunk->chunk_hdr->length);
      padding = WORD_ROUND(len) - len;

      /* Fixup cloned skb with just this chunks data.  */
      skb_trim(skb, chunk->chunk_end - padding - skb->data);

      /* Embed the event fields inside the cloned skb.  */
      event = sctp_skb2event(skb);

      /* Initialize event with flags 0  and correct length
       * Since this is a clone of the original skb, only account for
       * the data of this chunk as other chunks will be accounted separately.
       */
      sctp_ulpevent_init(event, 0, skb->len + sizeof(struct sk_buff));

      sctp_ulpevent_receive_data(event, asoc);

      event->stream = ntohs(chunk->subh.data_hdr->stream);
      event->ssn = ntohs(chunk->subh.data_hdr->ssn);
      event->ppid = chunk->subh.data_hdr->ppid;
      if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED) {
            event->flags |= SCTP_UNORDERED;
            event->cumtsn = sctp_tsnmap_get_ctsn(&asoc->peer.tsn_map);
      }
      event->tsn = ntohl(chunk->subh.data_hdr->tsn);
      event->msg_flags |= chunk->chunk_hdr->flags;
      event->iif = sctp_chunk_iif(chunk);

fail:
      return event;
}

/* Create a partial delivery related event.
 *
 * 5.3.1.7 SCTP_PARTIAL_DELIVERY_EVENT
 *
 *   When a receiver is engaged in a partial delivery of a
 *   message this notification will be used to indicate
 *   various events.
 */
struct sctp_ulpevent *sctp_ulpevent_make_pdapi(
      const struct sctp_association *asoc, __u32 indication,
      gfp_t gfp)
{
      struct sctp_ulpevent *event;
      struct sctp_pdapi_event *pd;
      struct sk_buff *skb;

      event = sctp_ulpevent_new(sizeof(struct sctp_pdapi_event),
                          MSG_NOTIFICATION, gfp);
      if (!event)
            goto fail;

      skb = sctp_event2skb(event);
      pd = (struct sctp_pdapi_event *)
            skb_put(skb, sizeof(struct sctp_pdapi_event));

      /* pdapi_type
       *   It should be SCTP_PARTIAL_DELIVERY_EVENT
       *
       * pdapi_flags: 16 bits (unsigned integer)
       *   Currently unused.
       */
      pd->pdapi_type = SCTP_PARTIAL_DELIVERY_EVENT;
      pd->pdapi_flags = 0;

      /* pdapi_length: 32 bits (unsigned integer)
       *
       * This field is the total length of the notification data, including
       * the notification header.  It will generally be sizeof (struct
       * sctp_pdapi_event).
       */
      pd->pdapi_length = sizeof(struct sctp_pdapi_event);

      /*  pdapi_indication: 32 bits (unsigned integer)
       *
       * This field holds the indication being sent to the application.
       */
      pd->pdapi_indication = indication;

      /*  pdapi_assoc_id: sizeof (sctp_assoc_t)
       *
       * The association id field, holds the identifier for the association.
       */
      sctp_ulpevent_set_owner(event, asoc);
      pd->pdapi_assoc_id = sctp_assoc2id(asoc);

      return event;
fail:
      return NULL;
}

struct sctp_ulpevent *sctp_ulpevent_make_authkey(
      const struct sctp_association *asoc, __u16 key_id,
      __u32 indication, gfp_t gfp)
{
      struct sctp_ulpevent *event;
      struct sctp_authkey_event *ak;
      struct sk_buff *skb;

      event = sctp_ulpevent_new(sizeof(struct sctp_authkey_event),
                          MSG_NOTIFICATION, gfp);
      if (!event)
            goto fail;

      skb = sctp_event2skb(event);
      ak = (struct sctp_authkey_event *)
            skb_put(skb, sizeof(struct sctp_authkey_event));

      ak->auth_type = SCTP_AUTHENTICATION_INDICATION;
      ak->auth_flags = 0;
      ak->auth_length = sizeof(struct sctp_authkey_event);

      ak->auth_keynumber = key_id;
      ak->auth_altkeynumber = 0;
      ak->auth_indication = indication;

      /*
       * The association id field, holds the identifier for the association.
       */
      sctp_ulpevent_set_owner(event, asoc);
      ak->auth_assoc_id = sctp_assoc2id(asoc);

      return event;
fail:
      return NULL;
}


/* Return the notification type, assuming this is a notification
 * event.
 */
__u16 sctp_ulpevent_get_notification_type(const struct sctp_ulpevent *event)
{
      union sctp_notification *notification;
      struct sk_buff *skb;

      skb = sctp_event2skb((struct sctp_ulpevent *)event);
      notification = (union sctp_notification *) skb->data;
      return notification->sn_header.sn_type;
}

/* Copy out the sndrcvinfo into a msghdr.  */
void sctp_ulpevent_read_sndrcvinfo(const struct sctp_ulpevent *event,
                           struct msghdr *msghdr)
{
      struct sctp_sndrcvinfo sinfo;

      if (sctp_ulpevent_is_notification(event))
            return;

      /* Sockets API Extensions for SCTP
       * Section 5.2.2 SCTP Header Information Structure (SCTP_SNDRCV)
       *
       * sinfo_stream: 16 bits (unsigned integer)
       *
       * For recvmsg() the SCTP stack places the message's stream number in
       * this value.
      */
      sinfo.sinfo_stream = event->stream;
      /* sinfo_ssn: 16 bits (unsigned integer)
       *
       * For recvmsg() this value contains the stream sequence number that
       * the remote endpoint placed in the DATA chunk.  For fragmented
       * messages this is the same number for all deliveries of the message
       * (if more than one recvmsg() is needed to read the message).
       */
      sinfo.sinfo_ssn = event->ssn;
      /* sinfo_ppid: 32 bits (unsigned integer)
       *
       * In recvmsg() this value is
       * the same information that was passed by the upper layer in the peer
       * application.  Please note that byte order issues are NOT accounted
       * for and this information is passed opaquely by the SCTP stack from
       * one end to the other.
       */
      sinfo.sinfo_ppid = event->ppid;
      /* sinfo_flags: 16 bits (unsigned integer)
       *
       * This field may contain any of the following flags and is composed of
       * a bitwise OR of these values.
       *
       * recvmsg() flags:
       *
       * SCTP_UNORDERED - This flag is present when the message was sent
       *                 non-ordered.
       */
      sinfo.sinfo_flags = event->flags;
      /* sinfo_tsn: 32 bit (unsigned integer)
       *
       * For the receiving side, this field holds a TSN that was
       * assigned to one of the SCTP Data Chunks.
       */
      sinfo.sinfo_tsn = event->tsn;
      /* sinfo_cumtsn: 32 bit (unsigned integer)
       *
       * This field will hold the current cumulative TSN as
       * known by the underlying SCTP layer.  Note this field is
       * ignored when sending and only valid for a receive
       * operation when sinfo_flags are set to SCTP_UNORDERED.
       */
      sinfo.sinfo_cumtsn = event->cumtsn;
      /* sinfo_assoc_id: sizeof (sctp_assoc_t)
       *
       * The association handle field, sinfo_assoc_id, holds the identifier
       * for the association announced in the COMMUNICATION_UP notification.
       * All notifications for a given association have the same identifier.
       * Ignored for one-to-one style sockets.
       */
      sinfo.sinfo_assoc_id = sctp_assoc2id(event->asoc);

      /* context value that is set via SCTP_CONTEXT socket option. */
      sinfo.sinfo_context = event->asoc->default_rcv_context;

      /* These fields are not used while receiving. */
      sinfo.sinfo_timetolive = 0;

      put_cmsg(msghdr, IPPROTO_SCTP, SCTP_SNDRCV,
             sizeof(struct sctp_sndrcvinfo), (void *)&sinfo);
}

/* Do accounting for bytes received and hold a reference to the association
 * for each skb.
 */
static void sctp_ulpevent_receive_data(struct sctp_ulpevent *event,
                               struct sctp_association *asoc)
{
      struct sk_buff *skb, *frag;

      skb = sctp_event2skb(event);
      /* Set the owner and charge rwnd for bytes received.  */
      sctp_ulpevent_set_owner(event, asoc);
      sctp_assoc_rwnd_decrease(asoc, skb_headlen(skb));

      if (!skb->data_len)
            return;

      /* Note:  Not clearing the entire event struct as this is just a
       * fragment of the real event.  However, we still need to do rwnd
       * accounting.
       * In general, the skb passed from IP can have only 1 level of
       * fragments. But we allow multiple levels of fragments.
       */
      for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next) {
            sctp_ulpevent_receive_data(sctp_skb2event(frag), asoc);
      }
}

/* Do accounting for bytes just read by user and release the references to
 * the association.
 */
static void sctp_ulpevent_release_data(struct sctp_ulpevent *event)
{
      struct sk_buff *skb, *frag;
      unsigned int      len;

      /* Current stack structures assume that the rcv buffer is
       * per socket.   For UDP style sockets this is not true as
       * multiple associations may be on a single UDP-style socket.
       * Use the local private area of the skb to track the owning
       * association.
       */

      skb = sctp_event2skb(event);
      len = skb->len;

      if (!skb->data_len)
            goto done;

      /* Don't forget the fragments. */
      for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next) {
            /* NOTE:  skb_shinfos are recursive. Although IP returns
             * skb's with only 1 level of fragments, SCTP reassembly can
             * increase the levels.
             */
            sctp_ulpevent_release_frag_data(sctp_skb2event(frag));
      }

done:
      sctp_assoc_rwnd_increase(event->asoc, len);
      sctp_ulpevent_release_owner(event);
}

static void sctp_ulpevent_release_frag_data(struct sctp_ulpevent *event)
{
      struct sk_buff *skb, *frag;

      skb = sctp_event2skb(event);

      if (!skb->data_len)
            goto done;

      /* Don't forget the fragments. */
      for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next) {
            /* NOTE:  skb_shinfos are recursive. Although IP returns
             * skb's with only 1 level of fragments, SCTP reassembly can
             * increase the levels.
             */
            sctp_ulpevent_release_frag_data(sctp_skb2event(frag));
      }

done:
      sctp_ulpevent_release_owner(event);
}

/* Free a ulpevent that has an owner.  It includes releasing the reference
 * to the owner, updating the rwnd in case of a DATA event and freeing the
 * skb.
 */
void sctp_ulpevent_free(struct sctp_ulpevent *event)
{
      if (sctp_ulpevent_is_notification(event))
            sctp_ulpevent_release_owner(event);
      else
            sctp_ulpevent_release_data(event);

      kfree_skb(sctp_event2skb(event));
}

/* Purge the skb lists holding ulpevents. */
void sctp_queue_purge_ulpevents(struct sk_buff_head *list)
{
      struct sk_buff *skb;
      while ((skb = skb_dequeue(list)) != NULL)
            sctp_ulpevent_free(sctp_skb2event(skb));
}

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