/* SCTP kernel reference Implementation * Copyright (c) 1999-2000 Cisco, Inc. * Copyright (c) 1999-2001 Motorola, Inc. * Copyright (c) 2001 International Business Machines, Corp. * 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 sctp_ulpevent_t 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> * * 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_set_owner_r(struct sk_buff *skb, sctp_association_t *asoc); static void sctp_ulpevent_set_owner(struct sk_buff *skb, const sctp_association_t *asoc); /* Create a new sctp_ulpevent. */ sctp_ulpevent_t *sctp_ulpevent_new(int size, int msg_flags, int priority) { sctp_ulpevent_t *event; struct sk_buff *skb; skb = alloc_skb(size, priority); if (!skb) goto fail; event = (sctp_ulpevent_t *) skb->cb; event = sctp_ulpevent_init(event, skb, msg_flags); if (!event) goto fail_init; event->malloced = 1; return event; fail_init: kfree_skb(event->parent); fail: return NULL; } /* Initialize an ULP event from an given skb. */ sctp_ulpevent_t *sctp_ulpevent_init(sctp_ulpevent_t *event, struct sk_buff *parent, int msg_flags) { memset(event, sizeof(sctp_ulpevent_t), 0x00); event->msg_flags = msg_flags; event->parent = parent; event->malloced = 0; return event; } /* Dispose of an event. */ void sctp_ulpevent_free(sctp_ulpevent_t *event) { if (event->malloced) kfree_skb(event->parent); } /* Is this a MSG_NOTIFICATION? */ int sctp_ulpevent_is_notification(const sctp_ulpevent_t *event) { return event->msg_flags & MSG_NOTIFICATION; } /* 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. */ sctp_ulpevent_t *sctp_ulpevent_make_assoc_change(const sctp_association_t *asoc, __u16 flags, __u16 state, __u16 error, __u16 outbound, __u16 inbound, int priority) { sctp_ulpevent_t *event; struct sctp_assoc_change *sac; event = sctp_ulpevent_new(sizeof(struct sctp_assoc_change), MSG_NOTIFICATION, priority); if (!event) goto fail; sac = (struct sctp_assoc_change *) skb_put(event->parent, 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->parent, 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. */ sctp_ulpevent_t *sctp_ulpevent_make_peer_addr_change( const sctp_association_t *asoc, const struct sockaddr_storage *aaddr, int flags, int state, int error, int priority) { sctp_ulpevent_t *event; struct sctp_paddr_change *spc; event = sctp_ulpevent_new(sizeof(struct sctp_paddr_change), MSG_NOTIFICATION, priority); if (!event) goto fail; spc = (struct sctp_paddr_change *) skb_put(event->parent, 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->parent, 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)); 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. */ sctp_ulpevent_t *sctp_ulpevent_make_remote_error(const sctp_association_t *asoc, sctp_chunk_t *chunk, __u16 flags, int priority) { sctp_ulpevent_t *event; struct sctp_remote_error *sre; struct sk_buff *skb; sctp_errhdr_t *ch; __u16 cause; int elen; ch = (sctp_errhdr_t *)(chunk->skb->data); cause = ch->cause; elen = 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), /* headroom */ 0, /* tailroom */ priority); /* 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_ulpevent_t *) skb->cb; event = sctp_ulpevent_init(event, skb, MSG_NOTIFICATION); if (!event) goto fail; event->malloced = 1; 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->parent, 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 */ sctp_ulpevent_t *sctp_ulpevent_make_send_failed(const sctp_association_t *asoc, sctp_chunk_t *chunk, __u16 flags, __u32 error, int priority) { sctp_ulpevent_t *event; struct sctp_send_failed *ssf; struct sk_buff *skb; /* Make skb with more room so we can prepend notification. */ skb = skb_copy_expand(chunk->skb, sizeof(struct sctp_send_failed), /* headroom */ 0, /* tailroom */ priority); if (!skb) goto fail; /* Pull off the common chunk header and DATA header. */ skb_pull(skb, sizeof(sctp_data_chunk_t)); /* Embed the event fields inside the cloned skb. */ event = (sctp_ulpevent_t *) skb->cb; event = sctp_ulpevent_init(event, skb, MSG_NOTIFICATION); if (!event) goto fail; /* Mark as malloced, even though the constructor was not * called. */ event->malloced = 1; 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 = skb->len; /* 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)); /* 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->parent, 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 */ sctp_ulpevent_t *sctp_ulpevent_make_shutdown_event( const sctp_association_t *asoc, __u16 flags, int priority) { sctp_ulpevent_t *event; struct sctp_shutdown_event *sse; event = sctp_ulpevent_new(sizeof(struct sctp_assoc_change), MSG_NOTIFICATION, priority); if (!event) goto fail; sse = (struct sctp_shutdown_event *) skb_put(event->parent, 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->parent, asoc); sse->sse_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 - draft-01 * 5.2.2 SCTP Header Information Structure (SCTP_SNDRCV) */ sctp_ulpevent_t *sctp_ulpevent_make_rcvmsg(sctp_association_t *asoc, sctp_chunk_t *chunk, int priority) { sctp_ulpevent_t *event; struct sctp_sndrcvinfo *info; struct sk_buff *skb; size_t padding, len; /* Clone the original skb, sharing the data. */ skb = skb_clone(chunk->skb, priority); 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); /* Set up a destructor to do rwnd accounting. */ sctp_ulpevent_set_owner_r(skb, asoc); /* Embed the event fields inside the cloned skb. */ event = (sctp_ulpevent_t *) skb->cb; /* Initialize event with flags 0. */ event = sctp_ulpevent_init(event, skb, 0); if (!event) goto fail_init; event->malloced = 1; info = (struct sctp_sndrcvinfo *) &event->sndrcvinfo; /* 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. */ info->sinfo_stream = ntohs(chunk->subh.data_hdr->stream); /* Sockets API Extensions for SCTP * Section 5.2.2 SCTP Header Information Structure (SCTP_SNDRCV) * * 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). */ info->sinfo_ssn = ntohs(chunk->subh.data_hdr->ssn); /* Sockets API Extensions for SCTP * Section 5.2.2 SCTP Header Information Structure (SCTP_SNDRCV) * * 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. */ info->sinfo_ppid = ntohl(chunk->subh.data_hdr->ppid); /* Sockets API Extensions for SCTP * Section 5.2.2 SCTP Header Information Structure (SCTP_SNDRCV) * * 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: * * MSG_UNORDERED - This flag is present when the message was sent * non-ordered. */ if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED) info->sinfo_flags |= MSG_UNORDERED; /* FIXME: For reassembly, we need to have the fragmentation bits. * This really does not belong in the event structure, but * its difficult to fix everything at the same time. Eventually, * we should create and skb based chunk structure. This structure * storage can be converted to an event. --jgrimm */ event->chunk_flags = chunk->chunk_hdr->flags; /* With -04 draft, tsn moves into sndrcvinfo. */ info->sinfo_tsn = ntohl(chunk->subh.data_hdr->tsn); /* Context is not used on receive. */ info->sinfo_context = 0; /* Sockets API Extensions for SCTP * Section 5.2.2 SCTP Header Information Structure (SCTP_SNDRCV) * * 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 TCP-style sockets. */ info->sinfo_assoc_id = sctp_assoc2id(asoc); return event; fail_init: kfree_skb(skb); fail: return NULL; } /* Return the notification type, assuming this is a notification * event. */ __u16 sctp_ulpevent_get_notification_type(const sctp_ulpevent_t *event) { union sctp_notification *notification; notification = (union sctp_notification *) event->parent->data; return notification->h.sn_type; } /* Copy out the sndrcvinfo into a msghdr. */ void sctp_ulpevent_read_sndrcvinfo(const sctp_ulpevent_t *event, struct msghdr *msghdr) { if (!sctp_ulpevent_is_notification(event)) { put_cmsg(msghdr, IPPROTO_SCTP, SCTP_SNDRCV, sizeof(struct sctp_sndrcvinfo), (void *) &event->sndrcvinfo); } } /* Do accounting for bytes just read by user. */ static void sctp_rcvmsg_rfree(struct sk_buff *skb) { sctp_association_t *asoc; sctp_ulpevent_t *event; sctp_chunk_t *sack; struct timer_list *timer; /* 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. */ event = (sctp_ulpevent_t *) skb->cb; asoc = event->asoc; if (asoc->rwnd_over) { if (asoc->rwnd_over >= skb->len) { asoc->rwnd_over -= skb->len; } else { asoc->rwnd += (skb->len - asoc->rwnd_over); asoc->rwnd_over = 0; } } else { asoc->rwnd += skb->len; } SCTP_DEBUG_PRINTK("rwnd increased by %d to (%u, %u) - %u\n", skb->len, asoc->rwnd, asoc->rwnd_over, asoc->a_rwnd); /* Send a window update SACK if the rwnd has increased by at least the * minimum of the association's PMTU and half of the receive buffer. * The algorithm used is similar to the one described in Section 4.2.3.3 * of RFC 1122. */ if ((asoc->state == SCTP_STATE_ESTABLISHED) && (asoc->rwnd > asoc->a_rwnd) && ((asoc->rwnd - asoc->a_rwnd) >= min_t(__u32, (asoc->base.sk->rcvbuf >> 1), asoc->pmtu))) { SCTP_DEBUG_PRINTK("Sending window update SACK- rwnd: %u " "a_rwnd: %u\n", asoc->rwnd, asoc->a_rwnd); sack = sctp_make_sack(asoc); if (!sack) goto out; /* Update the last advertised rwnd value. */ asoc->a_rwnd = asoc->rwnd; asoc->peer.sack_needed = 0; asoc->peer.next_dup_tsn = 0; sctp_push_outqueue(&asoc->outqueue, sack); /* Stop the SACK timer. */ timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK]; if (timer_pending(timer) && del_timer(timer)) sctp_association_put(asoc); } out: sctp_association_put(asoc); } /* Charge receive window for bytes recieved. */ static void sctp_ulpevent_set_owner_r(struct sk_buff *skb, sctp_association_t *asoc) { sctp_ulpevent_t *event; /* The 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. * We use the local private area of the skb to track the owning * association. */ sctp_association_hold(asoc); skb->sk = asoc->base.sk; event = (sctp_ulpevent_t *) skb->cb; event->asoc = asoc; skb->destructor = sctp_rcvmsg_rfree; SCTP_ASSERT(asoc->rwnd, "rwnd zero", return); SCTP_ASSERT(!asoc->rwnd_over, "rwnd_over not zero", return); if (asoc->rwnd >= skb->len) { asoc->rwnd -= skb->len; } else { asoc->rwnd_over = skb->len - asoc->rwnd; asoc->rwnd = 0; } SCTP_DEBUG_PRINTK("rwnd decreased by %d to (%u, %u)\n", skb->len, asoc->rwnd, asoc->rwnd_over); } /* A simple destructor to give up the reference to the association. */ static void sctp_ulpevent_rfree(struct sk_buff *skb) { sctp_ulpevent_t *event; event = (sctp_ulpevent_t *)skb->cb; sctp_association_put(event->asoc); } /* Hold the association in case the msg_name needs read out of * the association. */ static void sctp_ulpevent_set_owner(struct sk_buff *skb, const sctp_association_t *asoc) { sctp_ulpevent_t *event; /* Cast away the const, as we are just wanting to * bump the reference count. */ sctp_association_hold((sctp_association_t *)asoc); skb->sk = asoc->base.sk; event = (sctp_ulpevent_t *)skb->cb; event->asoc = (sctp_association_t *)asoc; skb->destructor = sctp_ulpevent_rfree; }