// SPDX-License-Identifier: GPL-2.0-or-later

  /* 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.

   *

   * Please send any bug reports or fixes you make to the
   * email address(es):

   *    lksctp developers <linux-sctp@vger.kernel.org>

   *

   * Written or modified by:

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

   */

  #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);

  }
  
  /* 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;
  	}

  }
  
  /* 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);

  	if (chunk->asoc)
  		chunk->asoc->stats.ipackets++;

  	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;

  	struct sctp_chunkhdr *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 = (struct sctp_chunkhdr *)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;

  	struct sctp_chunkhdr *ch = NULL;

  
  	/* The assumption is that we are safe to process the chunks
  	 * at this time.
  	 */

  	chunk = queue->in_progress;
  	if (chunk) {

  		/* 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) {

  			if (chunk->head_skb == chunk->skb) {
  				chunk->skb = skb_shinfo(chunk->skb)->frag_list;
  				goto new_skb;
  			}
  			if (chunk->skb->next) {
  				chunk->skb = chunk->skb->next;
  				goto new_skb;
  			}
  
  			if (chunk->head_skb)
  				chunk->skb = chunk->head_skb;

  			sctp_chunk_free(chunk);
  			chunk = queue->in_progress = NULL;
  		} else {
  			/* Nothing to do. Next chunk in the packet, please. */

  			ch = (struct sctp_chunkhdr *)chunk->chunk_end;

  			/* Force chunk->skb->data to chunk->chunk_end.  */

  			skb_pull(chunk->skb, chunk->chunk_end - chunk->skb->data);
  			/* We are guaranteed to pull a SCTP header. */

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

  		struct list_head *entry;

  next_chunk:

  		/* Is the queue empty?  */

  		entry = sctp_list_dequeue(&queue->in_chunk_list);
  		if (!entry)

  			return NULL;

  		chunk = list_entry(entry, struct sctp_chunk, list);

  		if (skb_is_gso(chunk->skb) && skb_is_gso_sctp(chunk->skb)) {

  			/* GSO-marked skbs but without frags, handle
  			 * them normally
  			 */
  			if (skb_shinfo(chunk->skb)->frag_list)
  				chunk->head_skb = chunk->skb;
  
  			/* skbs with "cover letter" */
  			if (chunk->head_skb && chunk->skb->data_len == chunk->skb->len)
  				chunk->skb = skb_shinfo(chunk->skb)->frag_list;
  
  			if (WARN_ON(!chunk->skb)) {
  				__SCTP_INC_STATS(dev_net(chunk->skb->dev), SCTP_MIB_IN_PKT_DISCARDS);
  				sctp_chunk_free(chunk);
  				goto next_chunk;
  			}
  		}
  
  		if (chunk->asoc)
  			sock_rps_save_rxhash(chunk->asoc->base.sk, chunk->skb);

  		queue->in_progress = chunk;

  new_skb:

  		/* This is the first chunk in the packet.  */

  		ch = (struct sctp_chunkhdr *)chunk->skb->data;

  		chunk->singleton = 1;

  		chunk->data_accepted = 0;

  		chunk->pdiscard = 0;
  		chunk->auth = 0;
  		chunk->has_asconf = 0;
  		chunk->end_of_packet = 0;

  		if (chunk->head_skb) {
  			struct sctp_input_cb
  				*cb = SCTP_INPUT_CB(chunk->skb),
  				*head_cb = SCTP_INPUT_CB(chunk->head_skb);
  
  			cb->chunk = head_cb->chunk;

  			cb->af = head_cb->af;

  		}

  	}

  	chunk->chunk_hdr = ch;

  	chunk->chunk_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length));

  	skb_pull(chunk->skb, sizeof(*ch));

  	chunk->subh.v = NULL; /* Subheader is no longer valid.  */

  	if (chunk->chunk_end + sizeof(*ch) <= skb_tail_pointer(chunk->skb)) {

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

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

  		/* Discard inside state machine. */
  		chunk->pdiscard = 1;
  		chunk->chunk_end = skb_tail_pointer(chunk->skb);

  	} 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;
  	}

  	pr_debug("+++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);

  }