ulpevent.c

在linux环境下的流控制传输协议（sctp）的源代码

	 * 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_rmem_schedule(asoc->base.sk, chunk->skb->truesize)))
			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(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));
}