/* 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 * * This abstraction carries sctp events 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> *    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/sock.h>#include <net/sctp/structs.h>#include <net/sctp/sctp.h>#include <net/sctp/sm.h> /* Forward declarations for internal helpers.  */static struct sctp_ulpevent * sctp_ulpq_reasm(struct sctp_ulpq *ulpq,					      struct sctp_ulpevent *);static struct sctp_ulpevent * sctp_ulpq_order(struct sctp_ulpq *,					      struct sctp_ulpevent *); /* 1st Level Abstractions */ /* Initialize a ULP queue from a block of memory.  */struct sctp_ulpq *sctp_ulpq_init(struct sctp_ulpq *ulpq,				 struct sctp_association *asoc){	memset(ulpq, 0, sizeof(struct sctp_ulpq)); 	ulpq->asoc = asoc;	skb_queue_head_init(&ulpq->reasm);	skb_queue_head_init(&ulpq->lobby);	ulpq->pd_mode  = 0;	ulpq->malloced = 0; 	return ulpq;}  /* Flush the reassembly and ordering queues.  */static void sctp_ulpq_flush(struct sctp_ulpq *ulpq){	struct sk_buff *skb;	struct sctp_ulpevent *event; 	while ((skb = __skb_dequeue(&ulpq->lobby)) != NULL) {		event = sctp_skb2event(skb);		sctp_ulpevent_free(event);	} 	while ((skb = __skb_dequeue(&ulpq->reasm)) != NULL) {		event = sctp_skb2event(skb);		sctp_ulpevent_free(event);	} } /* Dispose of a ulpqueue.  */void sctp_ulpq_free(struct sctp_ulpq *ulpq){	sctp_ulpq_flush(ulpq);	if (ulpq->malloced)		kfree(ulpq);} /* Process an incoming DATA chunk.  */int sctp_ulpq_tail_data(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk,			gfp_t gfp){	struct sk_buff_head temp;	sctp_data_chunk_t *hdr;	struct sctp_ulpevent *event; 	hdr = (sctp_data_chunk_t *) chunk->chunk_hdr; 	/* Create an event from the incoming chunk. */	event = sctp_ulpevent_make_rcvmsg(chunk->asoc, chunk, gfp);	if (!event)		return -ENOMEM; 	/* Do reassembly if needed.  */	event = sctp_ulpq_reasm(ulpq, event); 	/* Do ordering if needed.  */	if ((event) && (event->msg_flags & MSG_EOR)){		/* Create a temporary list to collect chunks on.  */		skb_queue_head_init(&temp);		__skb_queue_tail(&temp, sctp_event2skb(event)); 		event = sctp_ulpq_order(ulpq, event);	} 	/* Send event to the ULP.  'event' is the sctp_ulpevent for	 * very first SKB on the 'temp' list.	 */	if (event)		sctp_ulpq_tail_event(ulpq, event); 	return 0;} /* Add a new event for propagation to the ULP.  *//* Clear the partial delivery mode for this socket.   Note: This * assumes that no association is currently in partial delivery mode. */int sctp_clear_pd(struct sock *sk){	struct sctp_sock *sp = sctp_sk(sk); 	sp->pd_mode = 0;	if (!skb_queue_empty(&sp->pd_lobby)) {		struct list_head *list;		sctp_skb_list_tail(&sp->pd_lobby, &sk->sk_receive_queue);		list = (struct list_head *)&sctp_sk(sk)->pd_lobby;		INIT_LIST_HEAD(list);		return 1;	}	return 0;} /* Clear the pd_mode and restart any pending messages waiting for delivery. */static int sctp_ulpq_clear_pd(struct sctp_ulpq *ulpq){	ulpq->pd_mode = 0;	return sctp_clear_pd(ulpq->asoc->base.sk);} /* If the SKB of 'event' is on a list, it is the first such member * of that list. */int sctp_ulpq_tail_event(struct sctp_ulpq *ulpq, struct sctp_ulpevent *event){	struct sock *sk = ulpq->asoc->base.sk;	struct sk_buff_head *queue, *skb_list;	struct sk_buff *skb = sctp_event2skb(event);	int clear_pd = 0; 	skb_list = (struct sk_buff_head *) skb->prev; 	/* If the socket is just going to throw this away, do not	 * even try to deliver it.	 */	if (sock_flag(sk, SOCK_DEAD) || (sk->sk_shutdown & RCV_SHUTDOWN))		goto out_free; 	/* Check if the user wishes to receive this event.  */	if (!sctp_ulpevent_is_enabled(event, &sctp_sk(sk)->subscribe))		goto out_free; 	/* If we are in partial delivery mode, post to the lobby until	 * partial delivery is cleared, unless, of course _this_ is	 * the association the cause of the partial delivery.	 */ 	if (!sctp_sk(sk)->pd_mode) {		queue = &sk->sk_receive_queue;	} else if (ulpq->pd_mode) {		if (event->msg_flags & MSG_NOTIFICATION)		       	queue = &sctp_sk(sk)->pd_lobby;		else {			clear_pd = event->msg_flags & MSG_EOR;			queue = &sk->sk_receive_queue;		}	} else		queue = &sctp_sk(sk)->pd_lobby;  	/* If we are harvesting multiple skbs they will be	 * collected on a list.	 */	if (skb_list)		sctp_skb_list_tail(skb_list, queue);	else		__skb_queue_tail(queue, skb); 	/* Did we just complete partial delivery and need to get	 * rolling again?  Move pending data to the receive	 * queue.	 */	if (clear_pd)		sctp_ulpq_clear_pd(ulpq); 	if (queue == &sk->sk_receive_queue)		sk->sk_data_ready(sk, 0);	return 1; out_free:	if (skb_list)		sctp_queue_purge_ulpevents(skb_list);	else		sctp_ulpevent_free(event); 	return 0;} /* 2nd Level Abstractions */ /* Helper function to store chunks that need to be reassembled.  */static inline void sctp_ulpq_store_reasm(struct sctp_ulpq *ulpq,					 struct sctp_ulpevent *event){	struct sk_buff *pos;	struct sctp_ulpevent *cevent;	__u32 tsn, ctsn; 	tsn = event->tsn; 	/* See if it belongs at the end. */	pos = skb_peek_tail(&ulpq->reasm);	if (!pos) {		__skb_queue_tail(&ulpq->reasm, sctp_event2skb(event));		return;	} 	/* Short circuit just dropping it at the end. */	cevent = sctp_skb2event(pos);	ctsn = cevent->tsn;	if (TSN_lt(ctsn, tsn)) {		__skb_queue_tail(&ulpq->reasm, sctp_event2skb(event));		return;	} 	/* Find the right place in this list. We store them by TSN.  */	skb_queue_walk(&ulpq->reasm, pos) {		cevent = sctp_skb2event(pos);		ctsn = cevent->tsn; 		if (TSN_lt(tsn, ctsn))			break;	} 	/* Insert before pos. */	__skb_insert(sctp_event2skb(event), pos->prev, pos, &ulpq->reasm); } /* Helper function to return an event corresponding to the reassembled * datagram. * This routine creates a re-assembled skb given the first and last skb's * as stored in the reassembly queue. The skb's may be non-linear if the sctp * payload was fragmented on the way and ip had to reassemble them. * We add the rest of skb's to the first skb's fraglist. */static struct sctp_ulpevent *sctp_make_reassembled_event(struct sk_buff_head *queue, struct sk_buff *f_frag, struct sk_buff *l_frag){	struct sk_buff *pos;	struct sk_buff *new = NULL;	struct sctp_ulpevent *event;	struct sk_buff *pnext, *last;	struct sk_buff *list = skb_shinfo(f_frag)->frag_list; 	/* Store the pointer to the 2nd skb */	if (f_frag == l_frag)		pos = NULL;	else		pos = f_frag->next; 	/* Get the last skb in the f_frag's frag_list if present. */	for (last = list; list; last = list, list = list->next); 	/* Add the list of remaining fragments to the first fragments	 * frag_list.	 */	if (last)		last->next = pos; 	else { 		if (skb_cloned(f_frag)) { 			/* This is a cloned skb, we can't just modify 			 * the frag_list.  We need a new skb to do that. 			 * Instead of calling skb_unshare(), we'll do it 			 * ourselves since we need to delay the free. 			 */ 			new = skb_copy(f_frag, GFP_ATOMIC); 			if (!new) 				return NULL;	/* try again later */  			new->sk = f_frag->sk;  			skb_shinfo(new)->frag_list = pos; 		} else 			skb_shinfo(f_frag)->frag_list = pos; 	} 	/* Remove the first fragment from the reassembly queue.  */	__skb_unlink(f_frag, queue);  	/* if we did unshare, then free the old skb and re-assign */ 	if (new) { 		kfree_skb(f_frag); 		f_frag = new; 	} 	while (pos) { 		pnext = pos->next; 		/* Update the len and data_len fields of the first fragment. */		f_frag->len += pos->len;		f_frag->data_len += pos->len; 		/* Remove the fragment from the reassembly queue.  */		__skb_unlink(pos, queue);			/* Break if we have reached the last fragment.  */		if (pos == l_frag)			break;		pos->next = pnext;		pos = pnext;	}; 	event = sctp_skb2event(f_frag);	SCTP_INC_STATS(SCTP_MIB_REASMUSRMSGS); 	return event;}  /* Helper function to check if an incoming chunk has filled up the last * missing fragment in a SCTP datagram and return the corresponding event. */static inline struct sctp_ulpevent *sctp_ulpq_retrieve_reassembled(struct sctp_ulpq *ulpq){	struct sk_buff *pos;	struct sctp_ulpevent *cevent;	struct sk_buff *first_frag = NULL;	__u32 ctsn, next_tsn;	struct sctp_ulpevent *retval = NULL; 	/* Initialized to 0 just to avoid compiler warning message.  Will	 * never be used with this value. It is referenced only after it	 * is set when we find the first fragment of a message.	 */	next_tsn = 0; 	/* The chunks are held in the reasm queue sorted by TSN.	 * Walk through the queue sequentially and look for a sequence of	 * fragmented chunks that complete a datagram.	 * 'first_frag' and next_tsn are reset when we find a chunk which	 * is the first fragment of a datagram. Once these 2 fields are set	 * we expect to find the remaining middle fragments and the last	 * fragment in order. If not, first_frag is reset to NULL and we	 * start the next pass when we find another first fragment.	 */	skb_queue_walk(&ulpq->reasm, pos) {		cevent = sctp_skb2event(pos);		ctsn = cevent->tsn; 		switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {		case SCTP_DATA_FIRST_FRAG:			first_frag = pos;			next_tsn = ctsn + 1;			break; 		case SCTP_DATA_MIDDLE_FRAG:			if ((first_frag) && (ctsn == next_tsn))				next_tsn++;			else				first_frag = NULL;			break; 		case SCTP_DATA_LAST_FRAG:			if (first_frag && (ctsn == next_tsn))				goto found;			else				first_frag = NULL;			break;		}; 	}done:	return retval;found:	retval = sctp_make_reassembled_event(&ulpq->reasm, first_frag, pos);	if (retval)		retval->msg_flags |= MSG_EOR;	goto done;} /* Retrieve the next set of fragments of a partial message. */static inline struct sctp_ulpevent *sctp_ulpq_retrieve_partial(struct sctp_ulpq *ulpq){	struct sk_buff *pos, *last_frag, *first_frag;	struct sctp_ulpevent *cevent;	__u32 ctsn, next_tsn;	int is_last;	struct sctp_ulpevent *retval; 	/* The chunks are held in the reasm queue sorted by TSN.	 * Walk through the queue sequentially and look for the first	 * sequence of fragmented chunks.	 */ 	if (skb_queue_empty(&ulpq->reasm))		return NULL; 	last_frag = first_frag = NULL;	retval = NULL;	next_tsn = 0;	is_last = 0; 	skb_queue_walk(&ulpq->reasm, pos) {		cevent = sctp_skb2event(pos);		ctsn = cevent->tsn; 		switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {		case SCTP_DATA_MIDDLE_FRAG:			if (!first_frag) {				first_frag = pos;				next_tsn = ctsn + 1;				last_frag = pos;			} else if (next_tsn == ctsn)				next_tsn++;			else				goto done;			break;		case SCTP_DATA_LAST_FRAG:			if (!first_frag)				first_frag = pos;			else if (ctsn != next_tsn)				goto done;			last_frag = pos;			is_last = 1;			goto done;		default:			return NULL;		};	} 	/* We have the reassembled event. There is no need to look	 * further.	 */done:	retval = sctp_make_reassembled_event(&ulpq->reasm, first_frag, last_frag);	if (retval && is_last)		retval->msg_flags |= MSG_EOR; 	return retval;}  /* Helper function to reassemble chunks.  Hold chunks on the reasm queue that * need reassembling. */static struct sctp_ulpevent *sctp_ulpq_reasm(struct sctp_ulpq *ulpq,						struct sctp_ulpevent *event){	struct sctp_ulpevent *retval = NULL; 	/* Check if this is part of a fragmented message.  */	if (SCTP_DATA_NOT_FRAG == (event->msg_flags & SCTP_DATA_FRAG_MASK)) {		event->msg_flags |= MSG_EOR;		return event;	} 	sctp_ulpq_store_reasm(ulpq, event);	if (!ulpq->pd_mode)		retval = sctp_ulpq_retrieve_reassembled(ulpq);	else {		__u32 ctsn, ctsnap; 		/* Do not even bother unless this is the next tsn to		 * be delivered.		 */		ctsn = event->tsn;		ctsnap = sctp_tsnmap_get_ctsn(&ulpq->asoc->peer.tsn_map);

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