/* SCTP kernel implementation

   * Copyright (c) 1999-2000 Cisco, Inc.
   * Copyright (c) 1999-2001 Motorola, Inc.
   * Copyright (c) 2002 International Business Machines, Corp.

   *

   * This file is part of the SCTP kernel implementation

   *

   * These functions are the methods for accessing the SCTP inqueue.
   *
   * An SCTP inqueue is a queue into which you push SCTP packets
   * (which might be bundles or fragments of chunks) and out of which you
   * pop SCTP whole chunks.

   *

   * This SCTP 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.

   *

   * This SCTP 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:

   *    La Monte H.P. Yarroll <piggy@acm.org>
   *    Karl Knutson <karl@athena.chicago.il.us>

   *

   * Any bugs reported given to us we will try to fix... any fixes shared will
   * be incorporated into the next SCTP release.
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <net/sctp/sctp.h>
  #include <net/sctp/sm.h>
  #include <linux/interrupt.h>

  #include <linux/slab.h>

  
  /* Initialize an SCTP inqueue.  */
  void sctp_inq_init(struct sctp_inq *queue)
  {

  	INIT_LIST_HEAD(&queue->in_chunk_list);

  	queue->in_progress = NULL;
  
  	/* Create a task for delivering data.  */

  	INIT_WORK(&queue->immediate, NULL);

  
  	queue->malloced = 0;
  }
  
  /* Release the memory associated with an SCTP inqueue.  */
  void sctp_inq_free(struct sctp_inq *queue)
  {

  	struct sctp_chunk *chunk, *tmp;

  
  	/* Empty the queue.  */

  	list_for_each_entry_safe(chunk, tmp, &queue->in_chunk_list, list) {
  		list_del_init(&chunk->list);

  		sctp_chunk_free(chunk);

  	}

  
  	/* If there is a packet which is currently being worked on,
  	 * free it as well.
  	 */

  	if (queue->in_progress) {

  		sctp_chunk_free(queue->in_progress);

  		queue->in_progress = NULL;
  	}

  
  	if (queue->malloced) {
  		/* Dump the master memory segment.  */
  		kfree(queue);
  	}
  }
  
  /* Put a new packet in an SCTP inqueue.
   * We assume that packet->sctp_hdr is set and in host byte order.
   */

  void sctp_inq_push(struct sctp_inq *q, struct sctp_chunk *chunk)

  {
  	/* Directly call the packet handling routine. */

  	if (chunk->rcvr->dead) {
  		sctp_chunk_free(chunk);
  		return;
  	}

  
  	/* We are now calling this either from the soft interrupt
  	 * or from the backlog processing.
  	 * Eventually, we should clean up inqueue to not rely
  	 * on the BH related data structures.
  	 */

  	list_add_tail(&chunk->list, &q->in_chunk_list);

  	q->immediate.func(&q->immediate);

  }

  /* Peek at the next chunk on the inqeue. */
  struct sctp_chunkhdr *sctp_inq_peek(struct sctp_inq *queue)
  {
  	struct sctp_chunk *chunk;
  	sctp_chunkhdr_t *ch = NULL;
  
  	chunk = queue->in_progress;
  	/* If there is no more chunks in this packet, say so */
  	if (chunk->singleton ||
  	    chunk->end_of_packet ||
  	    chunk->pdiscard)
  		    return NULL;
  
  	ch = (sctp_chunkhdr_t *)chunk->chunk_end;
  
  	return ch;
  }

  /* Extract a chunk from an SCTP inqueue.
   *
   * WARNING:  If you need to put the chunk on another queue, you need to
   * make a shallow copy (clone) of it.
   */
  struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
  {
  	struct sctp_chunk *chunk;
  	sctp_chunkhdr_t *ch = NULL;
  
  	/* The assumption is that we are safe to process the chunks
  	 * at this time.
  	 */
  
  	if ((chunk = queue->in_progress)) {
  		/* There is a packet that we have been working on.
  		 * Any post processing work to do before we move on?
  		 */
  		if (chunk->singleton ||
  		    chunk->end_of_packet ||
  		    chunk->pdiscard) {
  			sctp_chunk_free(chunk);
  			chunk = queue->in_progress = NULL;
  		} else {
  			/* Nothing to do. Next chunk in the packet, please. */
  			ch = (sctp_chunkhdr_t *) chunk->chunk_end;
  
  			/* Force chunk->skb->data to chunk->chunk_end.  */
  			skb_pull(chunk->skb,
  				 chunk->chunk_end - chunk->skb->data);

  
  			/* Verify that we have at least chunk headers
  			 * worth of buffer left.
  			 */
  			if (skb_headlen(chunk->skb) < sizeof(sctp_chunkhdr_t)) {
  				sctp_chunk_free(chunk);
  				chunk = queue->in_progress = NULL;
  			}

  		}
  	}
  
  	/* Do we need to take the next packet out of the queue to process? */
  	if (!chunk) {

  		struct list_head *entry;

  		/* Is the queue empty?  */

  		if (list_empty(&queue->in_chunk_list))

  			return NULL;

  		entry = queue->in_chunk_list.next;

  		chunk = queue->in_progress =

  			list_entry(entry, struct sctp_chunk, list);
  		list_del_init(entry);

  
  		/* This is the first chunk in the packet.  */
  		chunk->singleton = 1;
  		ch = (sctp_chunkhdr_t *) chunk->skb->data;

  		chunk->data_accepted = 0;

  	}

  	chunk->chunk_hdr = ch;
  	chunk->chunk_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));

  	/* In the unlikely case of an IP reassembly, the skb could be
  	 * non-linear. If so, update chunk_end so that it doesn't go past
  	 * the skb->tail.
  	 */
  	if (unlikely(skb_is_nonlinear(chunk->skb))) {

  		if (chunk->chunk_end > skb_tail_pointer(chunk->skb))
  			chunk->chunk_end = skb_tail_pointer(chunk->skb);

  	}
  	skb_pull(chunk->skb, sizeof(sctp_chunkhdr_t));
  	chunk->subh.v = NULL; /* Subheader is no longer valid.  */

  	if (chunk->chunk_end < skb_tail_pointer(chunk->skb)) {

  		/* This is not a singleton */
  		chunk->singleton = 0;

  	} else if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) {

  		/* RFC 2960, Section 6.10  Bundling

  		 *
  		 * Partial chunks MUST NOT be placed in an SCTP packet.
  		 * If the receiver detects a partial chunk, it MUST drop

  		 * the chunk.

  		 *
  		 * Since the end of the chunk is past the end of our buffer
  		 * (which contains the whole packet, we can freely discard
  		 * the whole packet.
  		 */
  		sctp_chunk_free(chunk);
  		chunk = queue->in_progress = NULL;
  
  		return NULL;
  	} else {
  		/* We are at the end of the packet, so mark the chunk
  		 * in case we need to send a SACK.
  		 */
  		chunk->end_of_packet = 1;
  	}
  
  	SCTP_DEBUG_PRINTK("+++sctp_inq_pop+++ chunk %p[%s],"
  			  " length %d, skb->len %d
  ",chunk,
  			  sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
  			  ntohs(chunk->chunk_hdr->length), chunk->skb->len);
  	return chunk;
  }
  
  /* Set a top-half handler.
   *
   * Originally, we the top-half handler was scheduled as a BH.  We now
   * call the handler directly in sctp_inq_push() at a time that
   * we know we are lock safe.
   * The intent is that this routine will pull stuff out of the
   * inqueue and process it.
   */

  void sctp_inq_set_th_handler(struct sctp_inq *q, work_func_t callback)

  {

  	INIT_WORK(&q->immediate, callback);

  }