linux/net/dccp/output.c
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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
  24static inline void dccp_event_ack_sent(struct sock *sk)
  25{
  26        inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
  27}
  28
  29static 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 */
  42static 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                case DCCP_PKT_RESET:
  65                        break;
  66
  67                case DCCP_PKT_REQUEST:
  68                        set_ack = 0;
  69                        /* fall through */
  70
  71                case DCCP_PKT_SYNC:
  72                case DCCP_PKT_SYNCACK:
  73                        ackno = dcb->dccpd_ack_seq;
  74                        /* fall through */
  75                default:
  76                        /*
  77                         * Set owner/destructor: some skbs are allocated via
  78                         * alloc_skb (e.g. when retransmission may happen).
  79                         * Only Data, DataAck, and Reset packets should come
  80                         * through here with skb->sk set.
  81                         */
  82                        WARN_ON(skb->sk);
  83                        skb_set_owner_w(skb, sk);
  84                        break;
  85                }
  86
  87                dcb->dccpd_seq = dp->dccps_gss;
  88
  89                if (dccp_insert_options(sk, skb)) {
  90                        kfree_skb(skb);
  91                        return -EPROTO;
  92                }
  93
  94
  95                /* Build DCCP header and checksum it. */
  96                dh = dccp_zeroed_hdr(skb, dccp_header_size);
  97                dh->dccph_type  = dcb->dccpd_type;
  98                dh->dccph_sport = inet->sport;
  99                dh->dccph_dport = inet->dport;
 100                dh->dccph_doff  = (dccp_header_size + dcb->dccpd_opt_len) / 4;
 101                dh->dccph_ccval = dcb->dccpd_ccval;
 102                dh->dccph_cscov = dp->dccps_pcslen;
 103                /* XXX For now we're using only 48 bits sequence numbers */
 104                dh->dccph_x     = 1;
 105
 106                dp->dccps_awh = dp->dccps_gss;
 107                dccp_hdr_set_seq(dh, dp->dccps_gss);
 108                if (set_ack)
 109                        dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
 110
 111                switch (dcb->dccpd_type) {
 112                case DCCP_PKT_REQUEST:
 113                        dccp_hdr_request(skb)->dccph_req_service =
 114                                                        dp->dccps_service;
 115                        break;
 116                case DCCP_PKT_RESET:
 117                        dccp_hdr_reset(skb)->dccph_reset_code =
 118                                                        dcb->dccpd_reset_code;
 119                        break;
 120                }
 121
 122                icsk->icsk_af_ops->send_check(sk, 0, skb);
 123
 124                if (set_ack)
 125                        dccp_event_ack_sent(sk);
 126
 127                DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
 128
 129                memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 130                err = icsk->icsk_af_ops->queue_xmit(skb, 0);
 131                return net_xmit_eval(err);
 132        }
 133        return -ENOBUFS;
 134}
 135
 136unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
 137{
 138        struct inet_connection_sock *icsk = inet_csk(sk);
 139        struct dccp_sock *dp = dccp_sk(sk);
 140        int mss_now = (pmtu - icsk->icsk_af_ops->net_header_len -
 141                       sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext));
 142
 143        /* Now subtract optional transport overhead */
 144        mss_now -= icsk->icsk_ext_hdr_len;
 145
 146        /*
 147         * FIXME: this should come from the CCID infrastructure, where, say,
 148         * TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
 149         * put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
 150         * TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
 151         * make it a multiple of 4
 152         */
 153
 154        mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
 155
 156        /* And store cached results */
 157        icsk->icsk_pmtu_cookie = pmtu;
 158        dp->dccps_mss_cache = mss_now;
 159
 160        return mss_now;
 161}
 162
 163EXPORT_SYMBOL_GPL(dccp_sync_mss);
 164
 165void dccp_write_space(struct sock *sk)
 166{
 167        read_lock(&sk->sk_callback_lock);
 168
 169        if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
 170                wake_up_interruptible(sk->sk_sleep);
 171        /* Should agree with poll, otherwise some programs break */
 172        if (sock_writeable(sk))
 173                sk_wake_async(sk, 2, POLL_OUT);
 174
 175        read_unlock(&sk->sk_callback_lock);
 176}
 177
 178/**
 179 * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
 180 * @sk:    socket to wait for
 181 * @skb:   current skb to pass on for waiting
 182 * @delay: sleep timeout in milliseconds (> 0)
 183 * This function is called by default when the socket is closed, and
 184 * when a non-zero linger time is set on the socket. For consistency
 185 */
 186static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb, int delay)
 187{
 188        struct dccp_sock *dp = dccp_sk(sk);
 189        DEFINE_WAIT(wait);
 190        unsigned long jiffdelay;
 191        int rc;
 192
 193        do {
 194                dccp_pr_debug("delayed send by %d msec\n", delay);
 195                jiffdelay = msecs_to_jiffies(delay);
 196
 197                prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
 198
 199                sk->sk_write_pending++;
 200                release_sock(sk);
 201                schedule_timeout(jiffdelay);
 202                lock_sock(sk);
 203                sk->sk_write_pending--;
 204
 205                if (sk->sk_err)
 206                        goto do_error;
 207                if (signal_pending(current))
 208                        goto do_interrupted;
 209
 210                rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb);
 211        } while ((delay = rc) > 0);
 212out:
 213        finish_wait(sk->sk_sleep, &wait);
 214        return rc;
 215
 216do_error:
 217        rc = -EPIPE;
 218        goto out;
 219do_interrupted:
 220        rc = -EINTR;
 221        goto out;
 222}
 223
 224void dccp_write_xmit(struct sock *sk, int block)
 225{
 226        struct dccp_sock *dp = dccp_sk(sk);
 227        struct sk_buff *skb;
 228
 229        while ((skb = skb_peek(&sk->sk_write_queue))) {
 230                int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb);
 231
 232                if (err > 0) {
 233                        if (!block) {
 234                                sk_reset_timer(sk, &dp->dccps_xmit_timer,
 235                                                msecs_to_jiffies(err)+jiffies);
 236                                break;
 237                        } else
 238                                err = dccp_wait_for_ccid(sk, skb, err);
 239                        if (err && err != -EINTR)
 240                                DCCP_BUG("err=%d after dccp_wait_for_ccid", err);
 241                }
 242
 243                skb_dequeue(&sk->sk_write_queue);
 244                if (err == 0) {
 245                        struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 246                        const int len = skb->len;
 247
 248                        if (sk->sk_state == DCCP_PARTOPEN) {
 249                                /* See 8.1.5.  Handshake Completion */
 250                                inet_csk_schedule_ack(sk);
 251                                inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
 252                                                  inet_csk(sk)->icsk_rto,
 253                                                  DCCP_RTO_MAX);
 254                                dcb->dccpd_type = DCCP_PKT_DATAACK;
 255                        } else if (dccp_ack_pending(sk))
 256                                dcb->dccpd_type = DCCP_PKT_DATAACK;
 257                        else
 258                                dcb->dccpd_type = DCCP_PKT_DATA;
 259
 260                        err = dccp_transmit_skb(sk, skb);
 261                        ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len);
 262                        if (err)
 263                                DCCP_BUG("err=%d after ccid_hc_tx_packet_sent",
 264                                         err);
 265                } else {
 266                        dccp_pr_debug("packet discarded due to err=%d\n", err);
 267                        kfree_skb(skb);
 268                }
 269        }
 270}
 271
 272int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
 273{
 274        if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk) != 0)
 275                return -EHOSTUNREACH; /* Routing failure or similar. */
 276
 277        return dccp_transmit_skb(sk, (skb_cloned(skb) ?
 278                                      pskb_copy(skb, GFP_ATOMIC):
 279                                      skb_clone(skb, GFP_ATOMIC)));
 280}
 281
 282struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
 283                                   struct request_sock *req)
 284{
 285        struct dccp_hdr *dh;
 286        struct dccp_request_sock *dreq;
 287        const u32 dccp_header_size = sizeof(struct dccp_hdr) +
 288                                     sizeof(struct dccp_hdr_ext) +
 289                                     sizeof(struct dccp_hdr_response);
 290        struct sk_buff *skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1,
 291                                           GFP_ATOMIC);
 292        if (skb == NULL)
 293                return NULL;
 294
 295        /* Reserve space for headers. */
 296        skb_reserve(skb, sk->sk_prot->max_header);
 297
 298        skb->dst = dst_clone(dst);
 299
 300        dreq = dccp_rsk(req);
 301        if (inet_rsk(req)->acked)       /* increase ISS upon retransmission */
 302                dccp_inc_seqno(&dreq->dreq_iss);
 303        DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
 304        DCCP_SKB_CB(skb)->dccpd_seq  = dreq->dreq_iss;
 305
 306        if (dccp_insert_options(sk, skb)) {
 307                kfree_skb(skb);
 308                return NULL;
 309        }
 310
 311        /* Build and checksum header */
 312        dh = dccp_zeroed_hdr(skb, dccp_header_size);
 313
 314        dh->dccph_sport = inet_sk(sk)->sport;
 315        dh->dccph_dport = inet_rsk(req)->rmt_port;
 316        dh->dccph_doff  = (dccp_header_size +
 317                           DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
 318        dh->dccph_type  = DCCP_PKT_RESPONSE;
 319        dh->dccph_x     = 1;
 320        dccp_hdr_set_seq(dh, dreq->dreq_iss);
 321        dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_isr);
 322        dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service;
 323
 324        dccp_csum_outgoing(skb);
 325
 326        /* We use `acked' to remember that a Response was already sent. */
 327        inet_rsk(req)->acked = 1;
 328        DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
 329        return skb;
 330}
 331
 332EXPORT_SYMBOL_GPL(dccp_make_response);
 333
 334/* answer offending packet in @rcv_skb with Reset from control socket @ctl */
 335struct sk_buff *dccp_ctl_make_reset(struct socket *ctl, struct sk_buff *rcv_skb)
 336{
 337        struct dccp_hdr *rxdh = dccp_hdr(rcv_skb), *dh;
 338        struct dccp_skb_cb *dcb = DCCP_SKB_CB(rcv_skb);
 339        const u32 dccp_hdr_reset_len = sizeof(struct dccp_hdr) +
 340                                       sizeof(struct dccp_hdr_ext) +
 341                                       sizeof(struct dccp_hdr_reset);
 342        struct dccp_hdr_reset *dhr;
 343        struct sk_buff *skb;
 344
 345        skb = alloc_skb(ctl->sk->sk_prot->max_header, GFP_ATOMIC);
 346        if (skb == NULL)
 347                return NULL;
 348
 349        skb_reserve(skb, ctl->sk->sk_prot->max_header);
 350
 351        /* Swap the send and the receive. */
 352        dh = dccp_zeroed_hdr(skb, dccp_hdr_reset_len);
 353        dh->dccph_type  = DCCP_PKT_RESET;
 354        dh->dccph_sport = rxdh->dccph_dport;
 355        dh->dccph_dport = rxdh->dccph_sport;
 356        dh->dccph_doff  = dccp_hdr_reset_len / 4;
 357        dh->dccph_x     = 1;
 358
 359        dhr = dccp_hdr_reset(skb);
 360        dhr->dccph_reset_code = dcb->dccpd_reset_code;
 361
 362        switch (dcb->dccpd_reset_code) {
 363        case DCCP_RESET_CODE_PACKET_ERROR:
 364                dhr->dccph_reset_data[0] = rxdh->dccph_type;
 365                break;
 366        case DCCP_RESET_CODE_OPTION_ERROR:      /* fall through */
 367        case DCCP_RESET_CODE_MANDATORY_ERROR:
 368                memcpy(dhr->dccph_reset_data, dcb->dccpd_reset_data, 3);
 369                break;
 370        }
 371        /*
 372         * From RFC 4340, 8.3.1:
 373         *   If P.ackno exists, set R.seqno := P.ackno + 1.
 374         *   Else set R.seqno := 0.
 375         */
 376        if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 377                dccp_hdr_set_seq(dh, ADD48(dcb->dccpd_ack_seq, 1));
 378        dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dcb->dccpd_seq);
 379
 380        dccp_csum_outgoing(skb);
 381        return skb;
 382}
 383
 384EXPORT_SYMBOL_GPL(dccp_ctl_make_reset);
 385
 386/* send Reset on established socket, to close or abort the connection */
 387int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code)
 388{
 389        struct sk_buff *skb;
 390        /*
 391         * FIXME: what if rebuild_header fails?
 392         * Should we be doing a rebuild_header here?
 393         */
 394        int err = inet_sk_rebuild_header(sk);
 395
 396        if (err != 0)
 397                return err;
 398
 399        skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1, GFP_ATOMIC);
 400        if (skb == NULL)
 401                return -ENOBUFS;
 402
 403        /* Reserve space for headers and prepare control bits. */
 404        skb_reserve(skb, sk->sk_prot->max_header);
 405        DCCP_SKB_CB(skb)->dccpd_type       = DCCP_PKT_RESET;
 406        DCCP_SKB_CB(skb)->dccpd_reset_code = code;
 407
 408        return dccp_transmit_skb(sk, skb);
 409}
 410
 411/*
 412 * Do all connect socket setups that can be done AF independent.
 413 */
 414static inline void dccp_connect_init(struct sock *sk)
 415{
 416        struct dccp_sock *dp = dccp_sk(sk);
 417        struct dst_entry *dst = __sk_dst_get(sk);
 418        struct inet_connection_sock *icsk = inet_csk(sk);
 419
 420        sk->sk_err = 0;
 421        sock_reset_flag(sk, SOCK_DONE);
 422
 423        dccp_sync_mss(sk, dst_mtu(dst));
 424
 425        /*
 426         * SWL and AWL are initially adjusted so that they are not less than
 427         * the initial Sequence Numbers received and sent, respectively:
 428         *      SWL := max(GSR + 1 - floor(W/4), ISR),
 429         *      AWL := max(GSS - W' + 1, ISS).
 430         * These adjustments MUST be applied only at the beginning of the
 431         * connection.
 432         */
 433        dccp_update_gss(sk, dp->dccps_iss);
 434        dccp_set_seqno(&dp->dccps_awl, max48(dp->dccps_awl, dp->dccps_iss));
 435
 436        /* S.GAR - greatest valid acknowledgement number received on a non-Sync;
 437         *         initialized to S.ISS (sec. 8.5)                            */
 438        dp->dccps_gar = dp->dccps_iss;
 439
 440        icsk->icsk_retransmits = 0;
 441}
 442
 443int dccp_connect(struct sock *sk)
 444{
 445        struct sk_buff *skb;
 446        struct inet_connection_sock *icsk = inet_csk(sk);
 447
 448        dccp_connect_init(sk);
 449
 450        skb = alloc_skb(sk->sk_prot->max_header, sk->sk_allocation);
 451        if (unlikely(skb == NULL))
 452                return -ENOBUFS;
 453
 454        /* Reserve space for headers. */
 455        skb_reserve(skb, sk->sk_prot->max_header);
 456
 457        DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
 458
 459        dccp_skb_entail(sk, skb);
 460        dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL));
 461        DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);
 462
 463        /* Timer for repeating the REQUEST until an answer. */
 464        inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
 465                                  icsk->icsk_rto, DCCP_RTO_MAX);
 466        return 0;
 467}
 468
 469EXPORT_SYMBOL_GPL(dccp_connect);
 470
 471void dccp_send_ack(struct sock *sk)
 472{
 473        /* If we have been reset, we may not send again. */
 474        if (sk->sk_state != DCCP_CLOSED) {
 475                struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header,
 476                                                GFP_ATOMIC);
 477
 478                if (skb == NULL) {
 479                        inet_csk_schedule_ack(sk);
 480                        inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
 481                        inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
 482                                                  TCP_DELACK_MAX,
 483                                                  DCCP_RTO_MAX);
 484                        return;
 485                }
 486
 487                /* Reserve space for headers */
 488                skb_reserve(skb, sk->sk_prot->max_header);
 489                DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
 490                dccp_transmit_skb(sk, skb);
 491        }
 492}
 493
 494EXPORT_SYMBOL_GPL(dccp_send_ack);
 495
 496/* FIXME: Is this still necessary (11.3) - currently nowhere used by DCCP. */
 497void dccp_send_delayed_ack(struct sock *sk)
 498{
 499        struct inet_connection_sock *icsk = inet_csk(sk);
 500        /*
 501         * FIXME: tune this timer. elapsed time fixes the skew, so no problem
 502         * with using 2s, and active senders also piggyback the ACK into a
 503         * DATAACK packet, so this is really for quiescent senders.
 504         */
 505        unsigned long timeout = jiffies + 2 * HZ;
 506
 507        /* Use new timeout only if there wasn't a older one earlier. */
 508        if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
 509                /* If delack timer was blocked or is about to expire,
 510                 * send ACK now.
 511                 *
 512                 * FIXME: check the "about to expire" part
 513                 */
 514                if (icsk->icsk_ack.blocked) {
 515                        dccp_send_ack(sk);
 516                        return;
 517                }
 518
 519                if (!time_before(timeout, icsk->icsk_ack.timeout))
 520                        timeout = icsk->icsk_ack.timeout;
 521        }
 522        icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
 523        icsk->icsk_ack.timeout = timeout;
 524        sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
 525}
 526
 527void dccp_send_sync(struct sock *sk, const u64 ackno,
 528                    const enum dccp_pkt_type pkt_type)
 529{
 530        /*
 531         * We are not putting this on the write queue, so
 532         * dccp_transmit_skb() will set the ownership to this
 533         * sock.
 534         */
 535        struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC);
 536
 537        if (skb == NULL) {
 538                /* FIXME: how to make sure the sync is sent? */
 539                DCCP_CRIT("could not send %s", dccp_packet_name(pkt_type));
 540                return;
 541        }
 542
 543        /* Reserve space for headers and prepare control bits. */
 544        skb_reserve(skb, sk->sk_prot->max_header);
 545        DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
 546        DCCP_SKB_CB(skb)->dccpd_ack_seq = ackno;
 547
 548        dccp_transmit_skb(sk, skb);
 549}
 550
 551EXPORT_SYMBOL_GPL(dccp_send_sync);
 552
 553/*
 554 * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
 555 * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
 556 * any circumstances.
 557 */
 558void dccp_send_close(struct sock *sk, const int active)
 559{
 560        struct dccp_sock *dp = dccp_sk(sk);
 561        struct sk_buff *skb;
 562        const gfp_t prio = active ? GFP_KERNEL : GFP_ATOMIC;
 563
 564        skb = alloc_skb(sk->sk_prot->max_header, prio);
 565        if (skb == NULL)
 566                return;
 567
 568        /* Reserve space for headers and prepare control bits. */
 569        skb_reserve(skb, sk->sk_prot->max_header);
 570        DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ?
 571                                        DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ;
 572
 573        if (active) {
 574                dccp_write_xmit(sk, 1);
 575                dccp_skb_entail(sk, skb);
 576                dccp_transmit_skb(sk, skb_clone(skb, prio));
 577                /* FIXME do we need a retransmit timer here? */
 578        } else
 579                dccp_transmit_skb(sk, skb);
 580}
 581