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   1 /*
   2  *  net/dccp/output.c
   3  *
   4  *  An implementation of the DCCP protocol
   5  *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   6  *
   7  *      This program is free software; you can redistribute it and/or
   8  *      modify it under the terms of the GNU General Public License
   9  *      as published by the Free Software Foundation; either version
  10  *      2 of the License, or (at your option) any later version.
  11  */
  12
  13 #include <linux/dccp.h>
  14 #include <linux/kernel.h>
  15 #include <linux/skbuff.h>
  16
  17 #include <net/inet_sock.h>
  18 #include <net/sock.h>
  19
  20 #include "ackvec.h"
  21 #include "ccid.h"
  22 #include "dccp.h"
  23
  24 static inline void dccp_event_ack_sent(struct sock *sk)
  25 {
  26         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
  27 }
  28
  29 static void dccp_skb_entail(struct sock *sk, struct sk_buff *skb)
  30 {
  31         skb_set_owner_w(skb, sk);
  32         WARN_ON(sk->sk_send_head);
  33         sk->sk_send_head = skb;
  34 }
  35
  36 /*
  37  * All SKB's seen here are completely headerless. It is our
  38  * job to build the DCCP header, and pass the packet down to
  39  * IP so it can do the same plus pass the packet off to the
  40  * device.
  41  */
  42 static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb)
  43 {
  44         if (likely(skb != NULL)) {
  45                 const struct inet_sock *inet = inet_sk(sk);
  46                 const struct inet_connection_sock *icsk = inet_csk(sk);
  47                 struct dccp_sock *dp = dccp_sk(sk);
  48                 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
  49                 struct dccp_hdr *dh;
  50                 /* XXX For now we're using only 48 bits sequence numbers */
  51                 const u32 dccp_header_size = sizeof(*dh) +
  52                                              sizeof(struct dccp_hdr_ext) +
  53                                           dccp_packet_hdr_len(dcb->dccpd_type);
  54                 int err, set_ack = 1;
  55                 u64 ackno = dp->dccps_gsr;
  56
  57                 dccp_inc_seqno(&dp->dccps_gss);
  58
  59                 switch (dcb->dccpd_type) {
  60                 case DCCP_PKT_DATA:
  61                         set_ack = 0;
  62                         /* fall through */
  63                 case DCCP_PKT_DATAACK:
  64                         break;
  65
  66                 case DCCP_PKT_REQUEST:
  67                         set_ack = 0;
  68                         /* fall through */
  69
  70                 case DCCP_PKT_SYNC:
  71                 case DCCP_PKT_SYNCACK:
  72                         ackno = dcb->dccpd_seq;
  73                         /* fall through */
  74                 default:
  75                         /*
  76                          * Only data packets should come through with skb->sk
  77                          * set.
  78                          */
  79                         WARN_ON(skb->sk);
  80                         skb_set_owner_w(skb, sk);
  81                         break;
  82                 }
  83
  84                 dcb->dccpd_seq = dp->dccps_gss;
  85
  86                 if (dccp_insert_options(sk, skb)) {
  87                         kfree_skb(skb);
  88                         return -EPROTO;
  89                 }
  90
  91
  92                 /* Build DCCP header and checksum it. */
  93                 dh = dccp_zeroed_hdr(skb, dccp_header_size);
  94                 dh->dccph_type  = dcb->dccpd_type;
  95                 dh->dccph_sport = inet->sport;
  96                 dh->dccph_dport = inet->dport;
  97                 dh->dccph_doff  = (dccp_header_size + dcb->dccpd_opt_len) / 4;
  98                 dh->dccph_ccval = dcb->dccpd_ccval;
  99                 dh->dccph_cscov = dp->dccps_pcslen;
 100                 /* XXX For now we're using only 48 bits sequence numbers */
 101                 dh->dccph_x     = 1;
 102
 103                 dp->dccps_awh = dp->dccps_gss;
 104                 dccp_hdr_set_seq(dh, dp->dccps_gss);
 105                 if (set_ack)
 106                         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
 107
 108                 switch (dcb->dccpd_type) {
 109                 case DCCP_PKT_REQUEST:
 110                         dccp_hdr_request(skb)->dccph_req_service =
 111                                                         dp->dccps_service;
 112                         break;
 113                 case DCCP_PKT_RESET:
 114                         dccp_hdr_reset(skb)->dccph_reset_code =
 115                                                         dcb->dccpd_reset_code;
 116                         break;
 117                 }
 118
 119                 icsk->icsk_af_ops->send_check(sk, 0, skb);
 120
 121                 if (set_ack)
 122                         dccp_event_ack_sent(sk);
 123
 124                 DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
 125
 126                 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 127                 err = icsk->icsk_af_ops->queue_xmit(skb, sk, 0);
 128                 return net_xmit_eval(err);
 129         }
 130         return -ENOBUFS;
 131 }
 132
 133 unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
 134 {
 135         struct inet_connection_sock *icsk = inet_csk(sk);
 136         struct dccp_sock *dp = dccp_sk(sk);
 137         int mss_now = (pmtu - icsk->icsk_af_ops->net_header_len -
 138                        sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext));
 139
 140         /* Now subtract optional transport overhead */
 141         mss_now -= icsk->icsk_ext_hdr_len;
 142
 143         /*
 144          * FIXME: this should come from the CCID infrastructure, where, say,
 145          * TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
 146          * put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
 147          * TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
 148          * make it a multiple of 4
 149          */
 150
 151         mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
 152
 153         /* And store cached results */
 154         icsk->icsk_pmtu_cookie = pmtu;
 155         dp->dccps_mss_cache = mss_now;
 156
 157         return mss_now;
 158 }
 159
 160 EXPORT_SYMBOL_GPL(dccp_sync_mss);
 161
 162 void dccp_write_space(struct sock *sk)
 163 {
 164         read_lock(&sk->sk_callback_lock);
 165
 166         if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
 167                 wake_up_interruptible(sk->sk_sleep);
 168         /* Should agree with poll, otherwise some programs break */
 169         if (sock_writeable(sk))
 170                 sk_wake_async(sk, 2, POLL_OUT);
 171
 172         read_unlock(&sk->sk_callback_lock);
 173 }
 174
 175 /**
 176  * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
 177  * @sk: socket to wait for
 178  * @timeo: for how long
 179  */
 180 static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb,
 181                               long *timeo)
 182 {
 183         struct dccp_sock *dp = dccp_sk(sk);
 184         DEFINE_WAIT(wait);
 185         long delay;
 186         int rc;
 187
 188         while (1) {
 189                 prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
 190
 191                 if (sk->sk_err)
 192                         goto do_error;
 193                 if (!*timeo)
 194                         goto do_nonblock;
 195                 if (signal_pending(current))
 196                         goto do_interrupted;
 197
 198                 rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
 199                                             skb->len);
 200                 if (rc <= 0)
 201                         break;
 202                 delay = msecs_to_jiffies(rc);
 203                 if (delay > *timeo || delay < 0)
 204                         goto do_nonblock;
 205
 206                 sk->sk_write_pending++;
 207                 release_sock(sk);
 208                 *timeo -= schedule_timeout(delay);
 209                 lock_sock(sk);
 210                 sk->sk_write_pending--;
 211         }
 212 out:
 213         finish_wait(sk->sk_sleep, &wait);
 214         return rc;
 215
 216 do_error:
 217         rc = -EPIPE;
 218         goto out;
 219 do_nonblock:
 220         rc = -EAGAIN;
 221         goto out;
 222 do_interrupted:
 223         rc = sock_intr_errno(*timeo);
 224         goto out;
 225 }
 226
 227 static void dccp_write_xmit_timer(unsigned long data) {
 228         struct sock *sk = (struct sock *)data;
 229         struct dccp_sock *dp = dccp_sk(sk);
 230
 231         bh_lock_sock(sk);
 232         if (sock_owned_by_user(sk))
 233                 sk_reset_timer(sk, &dp->dccps_xmit_timer, jiffies+1);
 234         else
 235                 dccp_write_xmit(sk, 0);
 236         bh_unlock_sock(sk);
 237         sock_put(sk);
 238 }
 239
 240 void dccp_write_xmit(struct sock *sk, int block)
 241 {
 242         struct dccp_sock *dp = dccp_sk(sk);
 243         struct sk_buff *skb;
 244         long timeo = DCCP_XMIT_TIMEO;   /* If a packet is taking longer than
 245                                            this we have other issues */
 246
 247         while ((skb = skb_peek(&sk->sk_write_queue))) {
 248                 int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
 249                                          skb->len);
 250
 251                 if (err > 0) {
 252                         if (!block) {
 253                                 sk_reset_timer(sk, &dp->dccps_xmit_timer,
 254                                                 msecs_to_jiffies(err)+jiffies);
 255                                 break;
 256                         } else {
 257                                 err = dccp_wait_for_ccid(sk, skb, &timeo);
 258                                 timeo = DCCP_XMIT_TIMEO;
 259                         }
 260                         if (err) {
 261                                 printk(KERN_CRIT "%s:err at dccp_wait_for_ccid"
 262                                                  " %d\n", __FUNCTION__, err);
 263                                 dump_stack();
 264                         }
 265                 }
 266
 267                 skb_dequeue(&sk->sk_write_queue);
 268                 if (err == 0) {
 269                         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 270                         const int len = skb->len;
 271
 272                         if (sk->sk_state == DCCP_PARTOPEN) {
 273                                 /* See 8.1.5.  Handshake Completion */
 274                                 inet_csk_schedule_ack(sk);
 275                                 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
 276                                                   inet_csk(sk)->icsk_rto,
 277                                                   DCCP_RTO_MAX);
 278                                 dcb->dccpd_type = DCCP_PKT_DATAACK;
 279                         } else if (dccp_ack_pending(sk))
 280                                 dcb->dccpd_type = DCCP_PKT_DATAACK;
 281                         else
 282                                 dcb->dccpd_type = DCCP_PKT_DATA;
 283
 284                         err = dccp_transmit_skb(sk, skb);
 285                         ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len);
 286                         if (err) {
 287                                 printk(KERN_CRIT "%s:err from "
 288                                                  "ccid_hc_tx_packet_sent %d\n",
 289                                                  __FUNCTION__, err);
 290                                 dump_stack();
 291                         }
 292                 } else
 293                         kfree(skb);
 294         }
 295 }
 296
 297 int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
 298 {
 299         if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk) != 0)
 300                 return -EHOSTUNREACH; /* Routing failure or similar. */
 301
 302         return dccp_transmit_skb(sk, (skb_cloned(skb) ?
 303                                       pskb_copy(skb, GFP_ATOMIC):
 304                                       skb_clone(skb, GFP_ATOMIC)));
 305 }
 306
 307 struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
 308                                    struct request_sock *req)
 309 {
 310         struct dccp_hdr *dh;
 311         struct dccp_request_sock *dreq;
 312         const u32 dccp_header_size = sizeof(struct dccp_hdr) +
 313                                      sizeof(struct dccp_hdr_ext) +
 314                                      sizeof(struct dccp_hdr_response);
 315         struct sk_buff *skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1,
 316                                            GFP_ATOMIC);
 317         if (skb == NULL)
 318                 return NULL;
 319
 320         /* Reserve space for headers. */
 321         skb_reserve(skb, sk->sk_prot->max_header);
 322
 323         skb->dst = dst_clone(dst);
 324
 325         dreq = dccp_rsk(req);
 326         if (inet_rsk(req)->acked)       /* increase ISS upon retransmission */
 327                 dccp_inc_seqno(&dreq->dreq_iss);
 328         DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
 329         DCCP_SKB_CB(skb)->dccpd_seq  = dreq->dreq_iss;
 330
 331         if (dccp_insert_options(sk, skb)) {
 332                 kfree_skb(skb);
 333                 return NULL;
 334         }
 335
 336         /* Build and checksum header */
 337         dh = dccp_zeroed_hdr(skb, dccp_header_size);
 338
 339         dh->dccph_sport = inet_sk(sk)->sport;
 340         dh->dccph_dport = inet_rsk(req)->rmt_port;
 341         dh->dccph_doff  = (dccp_header_size +
 342                            DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
 343         dh->dccph_type  = DCCP_PKT_RESPONSE;
 344         dh->dccph_x     = 1;
 345         dccp_hdr_set_seq(dh, dreq->dreq_iss);
 346         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_isr);
 347         dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service;
 348
 349         dccp_csum_outgoing(skb);
 350
 351         /* We use `acked' to remember that a Response was already sent. */
 352         inet_rsk(req)->acked = 1;
 353         DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
 354         return skb;
 355 }
 356
 357 EXPORT_SYMBOL_GPL(dccp_make_response);
 358
 359 static struct sk_buff *dccp_make_reset(struct sock *sk, struct dst_entry *dst,
 360                                        const enum dccp_reset_codes code)
 361
 362 {
 363         struct dccp_hdr *dh;
 364         struct dccp_sock *dp = dccp_sk(sk);
 365         const u32 dccp_header_size = sizeof(struct dccp_hdr) +
 366                                      sizeof(struct dccp_hdr_ext) +
 367                                      sizeof(struct dccp_hdr_reset);
 368         struct sk_buff *skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1,
 369                                            GFP_ATOMIC);
 370         if (skb == NULL)
 371                 return NULL;
 372
 373         /* Reserve space for headers. */
 374         skb_reserve(skb, sk->sk_prot->max_header);
 375
 376         skb->dst = dst_clone(dst);
 377
 378         dccp_inc_seqno(&dp->dccps_gss);
 379
 380         DCCP_SKB_CB(skb)->dccpd_reset_code = code;
 381         DCCP_SKB_CB(skb)->dccpd_type       = DCCP_PKT_RESET;
 382         DCCP_SKB_CB(skb)->dccpd_seq        = dp->dccps_gss;
 383
 384         if (dccp_insert_options(sk, skb)) {
 385                 kfree_skb(skb);
 386                 return NULL;
 387         }
 388
 389         dh = dccp_zeroed_hdr(skb, dccp_header_size);
 390
 391         dh->dccph_sport = inet_sk(sk)->sport;
 392         dh->dccph_dport = inet_sk(sk)->dport;
 393         dh->dccph_doff  = (dccp_header_size +
 394                            DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
 395         dh->dccph_type  = DCCP_PKT_RESET;
 396         dh->dccph_x     = 1;
 397         dccp_hdr_set_seq(dh, dp->dccps_gss);
 398         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr);
 399
 400         dccp_hdr_reset(skb)->dccph_reset_code = code;
 401         inet_csk(sk)->icsk_af_ops->send_check(sk, 0, skb);
 402
 403         DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
 404         return skb;
 405 }
 406
 407 int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code)
 408 {
 409         /*
 410          * FIXME: what if rebuild_header fails?
 411          * Should we be doing a rebuild_header here?
 412          */
 413         int err = inet_sk_rebuild_header(sk);
 414
 415         if (err == 0) {
 416                 struct sk_buff *skb = dccp_make_reset(sk, sk->sk_dst_cache,
 417                                                       code);
 418                 if (skb != NULL) {
 419                         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 420                         err = inet_csk(sk)->icsk_af_ops->queue_xmit(skb, sk, 0);
 421                         return net_xmit_eval(err);
 422                 }
 423         }
 424
 425         return err;
 426 }
 427
 428 /*
 429  * Do all connect socket setups that can be done AF independent.
 430  */
 431 static inline void dccp_connect_init(struct sock *sk)
 432 {
 433         struct dccp_sock *dp = dccp_sk(sk);
 434         struct dst_entry *dst = __sk_dst_get(sk);
 435         struct inet_connection_sock *icsk = inet_csk(sk);
 436
 437         sk->sk_err = 0;
 438         sock_reset_flag(sk, SOCK_DONE);
 439
 440         dccp_sync_mss(sk, dst_mtu(dst));
 441
 442         /*
 443          * SWL and AWL are initially adjusted so that they are not less than
 444          * the initial Sequence Numbers received and sent, respectively:
 445          *      SWL := max(GSR + 1 - floor(W/4), ISR),
 446          *      AWL := max(GSS - W' + 1, ISS).
 447          * These adjustments MUST be applied only at the beginning of the
 448          * connection.
 449          */
 450         dccp_update_gss(sk, dp->dccps_iss);
 451         dccp_set_seqno(&dp->dccps_awl, max48(dp->dccps_awl, dp->dccps_iss));
 452
 453         /* S.GAR - greatest valid acknowledgement number received on a non-Sync;
 454          *         initialized to S.ISS (sec. 8.5)                            */
 455         dp->dccps_gar = dp->dccps_iss;
 456
 457         icsk->icsk_retransmits = 0;
 458         init_timer(&dp->dccps_xmit_timer);
 459         dp->dccps_xmit_timer.data = (unsigned long)sk;
 460         dp->dccps_xmit_timer.function = dccp_write_xmit_timer;
 461 }
 462
 463 int dccp_connect(struct sock *sk)
 464 {
 465         struct sk_buff *skb;
 466         struct inet_connection_sock *icsk = inet_csk(sk);
 467
 468         dccp_connect_init(sk);
 469
 470         skb = alloc_skb(sk->sk_prot->max_header, sk->sk_allocation);
 471         if (unlikely(skb == NULL))
 472                 return -ENOBUFS;
 473
 474         /* Reserve space for headers. */
 475         skb_reserve(skb, sk->sk_prot->max_header);
 476
 477         DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
 478
 479         dccp_skb_entail(sk, skb);
 480         dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL));
 481         DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);
 482
 483         /* Timer for repeating the REQUEST until an answer. */
 484         inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
 485                                   icsk->icsk_rto, DCCP_RTO_MAX);
 486         return 0;
 487 }
 488
 489 EXPORT_SYMBOL_GPL(dccp_connect);
 490
 491 void dccp_send_ack(struct sock *sk)
 492 {
 493         /* If we have been reset, we may not send again. */
 494         if (sk->sk_state != DCCP_CLOSED) {
 495                 struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header,
 496                                                 GFP_ATOMIC);
 497
 498                 if (skb == NULL) {
 499                         inet_csk_schedule_ack(sk);
 500                         inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
 501                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
 502                                                   TCP_DELACK_MAX,
 503                                                   DCCP_RTO_MAX);
 504                         return;
 505                 }
 506
 507                 /* Reserve space for headers */
 508                 skb_reserve(skb, sk->sk_prot->max_header);
 509                 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
 510                 dccp_transmit_skb(sk, skb);
 511         }
 512 }
 513
 514 EXPORT_SYMBOL_GPL(dccp_send_ack);
 515
 516 void dccp_send_delayed_ack(struct sock *sk)
 517 {
 518         struct inet_connection_sock *icsk = inet_csk(sk);
 519         /*
 520          * FIXME: tune this timer. elapsed time fixes the skew, so no problem
 521          * with using 2s, and active senders also piggyback the ACK into a
 522          * DATAACK packet, so this is really for quiescent senders.
 523          */
 524         unsigned long timeout = jiffies + 2 * HZ;
 525
 526         /* Use new timeout only if there wasn't a older one earlier. */
 527         if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
 528                 /* If delack timer was blocked or is about to expire,
 529                  * send ACK now.
 530                  *
 531                  * FIXME: check the "about to expire" part
 532                  */
 533                 if (icsk->icsk_ack.blocked) {
 534                         dccp_send_ack(sk);
 535                         return;
 536                 }
 537
 538                 if (!time_before(timeout, icsk->icsk_ack.timeout))
 539                         timeout = icsk->icsk_ack.timeout;
 540         }
 541         icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
 542         icsk->icsk_ack.timeout = timeout;
 543         sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
 544 }
 545
 546 void dccp_send_sync(struct sock *sk, const u64 seq,
 547                     const enum dccp_pkt_type pkt_type)
 548 {
 549         /*
 550          * We are not putting this on the write queue, so
 551          * dccp_transmit_skb() will set the ownership to this
 552          * sock.
 553          */
 554         struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC);
 555
 556         if (skb == NULL)
 557                 /* FIXME: how to make sure the sync is sent? */
 558                 return;
 559
 560         /* Reserve space for headers and prepare control bits. */
 561         skb_reserve(skb, sk->sk_prot->max_header);
 562         DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
 563         DCCP_SKB_CB(skb)->dccpd_seq = seq;
 564
 565         dccp_transmit_skb(sk, skb);
 566 }
 567
 568 EXPORT_SYMBOL_GPL(dccp_send_sync);
 569
 570 /*
 571  * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
 572  * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
 573  * any circumstances.
 574  */
 575 void dccp_send_close(struct sock *sk, const int active)
 576 {
 577         struct dccp_sock *dp = dccp_sk(sk);
 578         struct sk_buff *skb;
 579         const gfp_t prio = active ? GFP_KERNEL : GFP_ATOMIC;
 580
 581         skb = alloc_skb(sk->sk_prot->max_header, prio);
 582         if (skb == NULL)
 583                 return;
 584
 585         /* Reserve space for headers and prepare control bits. */
 586         skb_reserve(skb, sk->sk_prot->max_header);
 587         DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ?
 588                                         DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ;
 589
 590         if (active) {
 591                 dccp_write_xmit(sk, 1);
 592                 dccp_skb_entail(sk, skb);
 593                 dccp_transmit_skb(sk, skb_clone(skb, prio));
 594                 /* FIXME do we need a retransmit timer here? */
 595         } else
 596                 dccp_transmit_skb(sk, skb);
 597 }