net/dccp/proto.c

   1 /*
   2  *  net/dccp/proto.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 modify it
   8  *      under the terms of the GNU General Public License version 2 as
   9  *      published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/dccp.h>
  13 #include <linux/module.h>
  14 #include <linux/types.h>
  15 #include <linux/sched.h>
  16 #include <linux/kernel.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/netdevice.h>
  19 #include <linux/in.h>
  20 #include <linux/if_arp.h>
  21 #include <linux/init.h>
  22 #include <linux/random.h>
  23 #include <linux/slab.h>
  24 #include <net/checksum.h>
  25
  26 #include <net/inet_sock.h>
  27 #include <net/sock.h>
  28 #include <net/xfrm.h>
  29
  30 #include <asm/ioctls.h>
  31 #include <linux/spinlock.h>
  32 #include <linux/timer.h>
  33 #include <linux/delay.h>
  34 #include <linux/poll.h>
  35
  36 #include "ccid.h"
  37 #include "dccp.h"
  38 #include "feat.h"
  39
  40 DEFINE_SNMP_STAT(struct dccp_mib, dccp_statistics) __read_mostly;
  41
  42 EXPORT_SYMBOL_GPL(dccp_statistics);
  43
  44 struct percpu_counter dccp_orphan_count;
  45 EXPORT_SYMBOL_GPL(dccp_orphan_count);
  46
  47 struct inet_hashinfo dccp_hashinfo;
  48 EXPORT_SYMBOL_GPL(dccp_hashinfo);
  49
  50 /* the maximum queue length for tx in packets. 0 is no limit */
  51 int sysctl_dccp_tx_qlen __read_mostly = 5;
  52
  53 #ifdef CONFIG_IP_DCCP_DEBUG
  54 static const char *dccp_state_name(const int state)
  55 {
  56         static const char *const dccp_state_names[] = {
  57         [DCCP_OPEN]             = "OPEN",
  58         [DCCP_REQUESTING]       = "REQUESTING",
  59         [DCCP_PARTOPEN]         = "PARTOPEN",
  60         [DCCP_LISTEN]           = "LISTEN",
  61         [DCCP_RESPOND]          = "RESPOND",
  62         [DCCP_CLOSING]          = "CLOSING",
  63         [DCCP_ACTIVE_CLOSEREQ]  = "CLOSEREQ",
  64         [DCCP_PASSIVE_CLOSE]    = "PASSIVE_CLOSE",
  65         [DCCP_PASSIVE_CLOSEREQ] = "PASSIVE_CLOSEREQ",
  66         [DCCP_TIME_WAIT]        = "TIME_WAIT",
  67         [DCCP_CLOSED]           = "CLOSED",
  68         };
  69
  70         if (state >= DCCP_MAX_STATES)
  71                 return "INVALID STATE!";
  72         else
  73                 return dccp_state_names[state];
  74 }
  75 #endif
  76
  77 void dccp_set_state(struct sock *sk, const int state)
  78 {
  79         const int oldstate = sk->sk_state;
  80
  81         dccp_pr_debug("%s(%p)  %s  -->  %s\n", dccp_role(sk), sk,
  82                       dccp_state_name(oldstate), dccp_state_name(state));
  83         WARN_ON(state == oldstate);
  84
  85         switch (state) {
  86         case DCCP_OPEN:
  87                 if (oldstate != DCCP_OPEN)
  88                         DCCP_INC_STATS(DCCP_MIB_CURRESTAB);
  89                 /* Client retransmits all Confirm options until entering OPEN */
  90                 if (oldstate == DCCP_PARTOPEN)
  91                         dccp_feat_list_purge(&dccp_sk(sk)->dccps_featneg);
  92                 break;
  93
  94         case DCCP_CLOSED:
  95                 if (oldstate == DCCP_OPEN || oldstate == DCCP_ACTIVE_CLOSEREQ ||
  96                     oldstate == DCCP_CLOSING)
  97                         DCCP_INC_STATS(DCCP_MIB_ESTABRESETS);
  98
  99                 sk->sk_prot->unhash(sk);
 100                 if (inet_csk(sk)->icsk_bind_hash != NULL &&
 101                     !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
 102                         inet_put_port(sk);
 103                 /* fall through */
 104         default:
 105                 if (oldstate == DCCP_OPEN)
 106                         DCCP_DEC_STATS(DCCP_MIB_CURRESTAB);
 107         }
 108
 109         /* Change state AFTER socket is unhashed to avoid closed
 110          * socket sitting in hash tables.
 111          */
 112         sk->sk_state = state;
 113 }
 114
 115 EXPORT_SYMBOL_GPL(dccp_set_state);
 116
 117 static void dccp_finish_passive_close(struct sock *sk)
 118 {
 119         switch (sk->sk_state) {
 120         case DCCP_PASSIVE_CLOSE:
 121                 /* Node (client or server) has received Close packet. */
 122                 dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED);
 123                 dccp_set_state(sk, DCCP_CLOSED);
 124                 break;
 125         case DCCP_PASSIVE_CLOSEREQ:
 126                 /*
 127                  * Client received CloseReq. We set the `active' flag so that
 128                  * dccp_send_close() retransmits the Close as per RFC 4340, 8.3.
 129                  */
 130                 dccp_send_close(sk, 1);
 131                 dccp_set_state(sk, DCCP_CLOSING);
 132         }
 133 }
 134
 135 void dccp_done(struct sock *sk)
 136 {
 137         dccp_set_state(sk, DCCP_CLOSED);
 138         dccp_clear_xmit_timers(sk);
 139
 140         sk->sk_shutdown = SHUTDOWN_MASK;
 141
 142         if (!sock_flag(sk, SOCK_DEAD))
 143                 sk->sk_state_change(sk);
 144         else
 145                 inet_csk_destroy_sock(sk);
 146 }
 147
 148 EXPORT_SYMBOL_GPL(dccp_done);
 149
 150 const char *dccp_packet_name(const int type)
 151 {
 152         static const char *const dccp_packet_names[] = {
 153                 [DCCP_PKT_REQUEST]  = "REQUEST",
 154                 [DCCP_PKT_RESPONSE] = "RESPONSE",
 155                 [DCCP_PKT_DATA]     = "DATA",
 156                 [DCCP_PKT_ACK]      = "ACK",
 157                 [DCCP_PKT_DATAACK]  = "DATAACK",
 158                 [DCCP_PKT_CLOSEREQ] = "CLOSEREQ",
 159                 [DCCP_PKT_CLOSE]    = "CLOSE",
 160                 [DCCP_PKT_RESET]    = "RESET",
 161                 [DCCP_PKT_SYNC]     = "SYNC",
 162                 [DCCP_PKT_SYNCACK]  = "SYNCACK",
 163         };
 164
 165         if (type >= DCCP_NR_PKT_TYPES)
 166                 return "INVALID";
 167         else
 168                 return dccp_packet_names[type];
 169 }
 170
 171 EXPORT_SYMBOL_GPL(dccp_packet_name);
 172
 173 int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized)
 174 {
 175         struct dccp_sock *dp = dccp_sk(sk);
 176         struct inet_connection_sock *icsk = inet_csk(sk);
 177
 178         icsk->icsk_rto          = DCCP_TIMEOUT_INIT;
 179         icsk->icsk_syn_retries  = sysctl_dccp_request_retries;
 180         sk->sk_state            = DCCP_CLOSED;
 181         sk->sk_write_space      = dccp_write_space;
 182         icsk->icsk_sync_mss     = dccp_sync_mss;
 183         dp->dccps_mss_cache     = 536;
 184         dp->dccps_rate_last     = jiffies;
 185         dp->dccps_role          = DCCP_ROLE_UNDEFINED;
 186         dp->dccps_service       = DCCP_SERVICE_CODE_IS_ABSENT;
 187         dp->dccps_tx_qlen       = sysctl_dccp_tx_qlen;
 188
 189         dccp_init_xmit_timers(sk);
 190
 191         INIT_LIST_HEAD(&dp->dccps_featneg);
 192         /* control socket doesn't need feat nego */
 193         if (likely(ctl_sock_initialized))
 194                 return dccp_feat_init(sk);
 195         return 0;
 196 }
 197
 198 EXPORT_SYMBOL_GPL(dccp_init_sock);
 199
 200 void dccp_destroy_sock(struct sock *sk)
 201 {
 202         struct dccp_sock *dp = dccp_sk(sk);
 203
 204         /*
 205          * DCCP doesn't use sk_write_queue, just sk_send_head
 206          * for retransmissions
 207          */
 208         if (sk->sk_send_head != NULL) {
 209                 kfree_skb(sk->sk_send_head);
 210                 sk->sk_send_head = NULL;
 211         }
 212
 213         /* Clean up a referenced DCCP bind bucket. */
 214         if (inet_csk(sk)->icsk_bind_hash != NULL)
 215                 inet_put_port(sk);
 216
 217         kfree(dp->dccps_service_list);
 218         dp->dccps_service_list = NULL;
 219
 220         if (dp->dccps_hc_rx_ackvec != NULL) {
 221                 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
 222                 dp->dccps_hc_rx_ackvec = NULL;
 223         }
 224         ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
 225         ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
 226         dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;
 227
 228         /* clean up feature negotiation state */
 229         dccp_feat_list_purge(&dp->dccps_featneg);
 230 }
 231
 232 EXPORT_SYMBOL_GPL(dccp_destroy_sock);
 233
 234 static inline int dccp_listen_start(struct sock *sk, int backlog)
 235 {
 236         struct dccp_sock *dp = dccp_sk(sk);
 237
 238         dp->dccps_role = DCCP_ROLE_LISTEN;
 239         /* do not start to listen if feature negotiation setup fails */
 240         if (dccp_feat_finalise_settings(dp))
 241                 return -EPROTO;
 242         return inet_csk_listen_start(sk, backlog);
 243 }
 244
 245 static inline int dccp_need_reset(int state)
 246 {
 247         return state != DCCP_CLOSED && state != DCCP_LISTEN &&
 248                state != DCCP_REQUESTING;
 249 }
 250
 251 int dccp_disconnect(struct sock *sk, int flags)
 252 {
 253         struct inet_connection_sock *icsk = inet_csk(sk);
 254         struct inet_sock *inet = inet_sk(sk);
 255         int err = 0;
 256         const int old_state = sk->sk_state;
 257
 258         if (old_state != DCCP_CLOSED)
 259                 dccp_set_state(sk, DCCP_CLOSED);
 260
 261         /*
 262          * This corresponds to the ABORT function of RFC793, sec. 3.8
 263          * TCP uses a RST segment, DCCP a Reset packet with Code 2, "Aborted".
 264          */
 265         if (old_state == DCCP_LISTEN) {
 266                 inet_csk_listen_stop(sk);
 267         } else if (dccp_need_reset(old_state)) {
 268                 dccp_send_reset(sk, DCCP_RESET_CODE_ABORTED);
 269                 sk->sk_err = ECONNRESET;
 270         } else if (old_state == DCCP_REQUESTING)
 271                 sk->sk_err = ECONNRESET;
 272
 273         dccp_clear_xmit_timers(sk);
 274
 275         __skb_queue_purge(&sk->sk_receive_queue);
 276         __skb_queue_purge(&sk->sk_write_queue);
 277         if (sk->sk_send_head != NULL) {
 278                 __kfree_skb(sk->sk_send_head);
 279                 sk->sk_send_head = NULL;
 280         }
 281
 282         inet->inet_dport = 0;
 283
 284         if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
 285                 inet_reset_saddr(sk);
 286
 287         sk->sk_shutdown = 0;
 288         sock_reset_flag(sk, SOCK_DONE);
 289
 290         icsk->icsk_backoff = 0;
 291         inet_csk_delack_init(sk);
 292         __sk_dst_reset(sk);
 293
 294         WARN_ON(inet->inet_num && !icsk->icsk_bind_hash);
 295
 296         sk->sk_error_report(sk);
 297         return err;
 298 }
 299
 300 EXPORT_SYMBOL_GPL(dccp_disconnect);
 301
 302 /*
 303  *      Wait for a DCCP event.
 304  *
 305  *      Note that we don't need to lock the socket, as the upper poll layers
 306  *      take care of normal races (between the test and the event) and we don't
 307  *      go look at any of the socket buffers directly.
 308  */
 309 unsigned int dccp_poll(struct file *file, struct socket *sock,
 310                        poll_table *wait)
 311 {
 312         unsigned int mask;
 313         struct sock *sk = sock->sk;
 314
 315         sock_poll_wait(file, sk_sleep(sk), wait);
 316         if (sk->sk_state == DCCP_LISTEN)
 317                 return inet_csk_listen_poll(sk);
 318
 319         /* Socket is not locked. We are protected from async events
 320            by poll logic and correct handling of state changes
 321            made by another threads is impossible in any case.
 322          */
 323
 324         mask = 0;
 325         if (sk->sk_err)
 326                 mask = POLLERR;
 327
 328         if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == DCCP_CLOSED)
 329                 mask |= POLLHUP;
 330         if (sk->sk_shutdown & RCV_SHUTDOWN)
 331                 mask |= POLLIN | POLLRDNORM | POLLRDHUP;
 332
 333         /* Connected? */
 334         if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_RESPOND)) {
 335                 if (atomic_read(&sk->sk_rmem_alloc) > 0)
 336                         mask |= POLLIN | POLLRDNORM;
 337
 338                 if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
 339                         if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
 340                                 mask |= POLLOUT | POLLWRNORM;
 341                         } else {  /* send SIGIO later */
 342                                 set_bit(SOCK_ASYNC_NOSPACE,
 343                                         &sk->sk_socket->flags);
 344                                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 345
 346                                 /* Race breaker. If space is freed after
 347                                  * wspace test but before the flags are set,
 348                                  * IO signal will be lost.
 349                                  */
 350                                 if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk))
 351                                         mask |= POLLOUT | POLLWRNORM;
 352                         }
 353                 }
 354         }
 355         return mask;
 356 }
 357
 358 EXPORT_SYMBOL_GPL(dccp_poll);
 359
 360 int dccp_ioctl(struct sock *sk, int cmd, unsigned long arg)
 361 {
 362         int rc = -ENOTCONN;
 363
 364         lock_sock(sk);
 365
 366         if (sk->sk_state == DCCP_LISTEN)
 367                 goto out;
 368
 369         switch (cmd) {
 370         case SIOCINQ: {
 371                 struct sk_buff *skb;
 372                 unsigned long amount = 0;
 373
 374                 skb = skb_peek(&sk->sk_receive_queue);
 375                 if (skb != NULL) {
 376                         /*
 377                          * We will only return the amount of this packet since
 378                          * that is all that will be read.
 379                          */
 380                         amount = skb->len;
 381                 }
 382                 rc = put_user(amount, (int __user *)arg);
 383         }
 384                 break;
 385         default:
 386                 rc = -ENOIOCTLCMD;
 387                 break;
 388         }
 389 out:
 390         release_sock(sk);
 391         return rc;
 392 }
 393
 394 EXPORT_SYMBOL_GPL(dccp_ioctl);
 395
 396 static int dccp_setsockopt_service(struct sock *sk, const __be32 service,
 397                                    char __user *optval, unsigned int optlen)
 398 {
 399         struct dccp_sock *dp = dccp_sk(sk);
 400         struct dccp_service_list *sl = NULL;
 401
 402         if (service == DCCP_SERVICE_INVALID_VALUE ||
 403             optlen > DCCP_SERVICE_LIST_MAX_LEN * sizeof(u32))
 404                 return -EINVAL;
 405
 406         if (optlen > sizeof(service)) {
 407                 sl = kmalloc(optlen, GFP_KERNEL);
 408                 if (sl == NULL)
 409                         return -ENOMEM;
 410
 411                 sl->dccpsl_nr = optlen / sizeof(u32) - 1;
 412                 if (copy_from_user(sl->dccpsl_list,
 413                                    optval + sizeof(service),
 414                                    optlen - sizeof(service)) ||
 415                     dccp_list_has_service(sl, DCCP_SERVICE_INVALID_VALUE)) {
 416                         kfree(sl);
 417                         return -EFAULT;
 418                 }
 419         }
 420
 421         lock_sock(sk);
 422         dp->dccps_service = service;
 423
 424         kfree(dp->dccps_service_list);
 425
 426         dp->dccps_service_list = sl;
 427         release_sock(sk);
 428         return 0;
 429 }
 430
 431 static int dccp_setsockopt_cscov(struct sock *sk, int cscov, bool rx)
 432 {
 433         u8 *list, len;
 434         int i, rc;
 435
 436         if (cscov < 0 || cscov > 15)
 437                 return -EINVAL;
 438         /*
 439          * Populate a list of permissible values, in the range cscov...15. This
 440          * is necessary since feature negotiation of single values only works if
 441          * both sides incidentally choose the same value. Since the list starts
 442          * lowest-value first, negotiation will pick the smallest shared value.
 443          */
 444         if (cscov == 0)
 445                 return 0;
 446         len = 16 - cscov;
 447
 448         list = kmalloc(len, GFP_KERNEL);
 449         if (list == NULL)
 450                 return -ENOBUFS;
 451
 452         for (i = 0; i < len; i++)
 453                 list[i] = cscov++;
 454
 455         rc = dccp_feat_register_sp(sk, DCCPF_MIN_CSUM_COVER, rx, list, len);
 456
 457         if (rc == 0) {
 458                 if (rx)
 459                         dccp_sk(sk)->dccps_pcrlen = cscov;
 460                 else
 461                         dccp_sk(sk)->dccps_pcslen = cscov;
 462         }
 463         kfree(list);
 464         return rc;
 465 }
 466
 467 static int dccp_setsockopt_ccid(struct sock *sk, int type,
 468                                 char __user *optval, unsigned int optlen)
 469 {
 470         u8 *val;
 471         int rc = 0;
 472
 473         if (optlen < 1 || optlen > DCCP_FEAT_MAX_SP_VALS)
 474                 return -EINVAL;
 475
 476         val = memdup_user(optval, optlen);
 477         if (IS_ERR(val))
 478                 return PTR_ERR(val);
 479
 480         lock_sock(sk);
 481         if (type == DCCP_SOCKOPT_TX_CCID || type == DCCP_SOCKOPT_CCID)
 482                 rc = dccp_feat_register_sp(sk, DCCPF_CCID, 1, val, optlen);
 483
 484         if (!rc && (type == DCCP_SOCKOPT_RX_CCID || type == DCCP_SOCKOPT_CCID))
 485                 rc = dccp_feat_register_sp(sk, DCCPF_CCID, 0, val, optlen);
 486         release_sock(sk);
 487
 488         kfree(val);
 489         return rc;
 490 }
 491
 492 static int do_dccp_setsockopt(struct sock *sk, int level, int optname,
 493                 char __user *optval, unsigned int optlen)
 494 {
 495         struct dccp_sock *dp = dccp_sk(sk);
 496         int val, err = 0;
 497
 498         switch (optname) {
 499         case DCCP_SOCKOPT_PACKET_SIZE:
 500                 DCCP_WARN("sockopt(PACKET_SIZE) is deprecated: fix your app\n");
 501                 return 0;
 502         case DCCP_SOCKOPT_CHANGE_L:
 503         case DCCP_SOCKOPT_CHANGE_R:
 504                 DCCP_WARN("sockopt(CHANGE_L/R) is deprecated: fix your app\n");
 505                 return 0;
 506         case DCCP_SOCKOPT_CCID:
 507         case DCCP_SOCKOPT_RX_CCID:
 508         case DCCP_SOCKOPT_TX_CCID:
 509                 return dccp_setsockopt_ccid(sk, optname, optval, optlen);
 510         }
 511
 512         if (optlen < (int)sizeof(int))
 513                 return -EINVAL;
 514
 515         if (get_user(val, (int __user *)optval))
 516                 return -EFAULT;
 517
 518         if (optname == DCCP_SOCKOPT_SERVICE)
 519                 return dccp_setsockopt_service(sk, val, optval, optlen);
 520
 521         lock_sock(sk);
 522         switch (optname) {
 523         case DCCP_SOCKOPT_SERVER_TIMEWAIT:
 524                 if (dp->dccps_role != DCCP_ROLE_SERVER)
 525                         err = -EOPNOTSUPP;
 526                 else
 527                         dp->dccps_server_timewait = (val != 0);
 528                 break;
 529         case DCCP_SOCKOPT_SEND_CSCOV:
 530                 err = dccp_setsockopt_cscov(sk, val, false);
 531                 break;
 532         case DCCP_SOCKOPT_RECV_CSCOV:
 533                 err = dccp_setsockopt_cscov(sk, val, true);
 534                 break;
 535         case DCCP_SOCKOPT_QPOLICY_ID:
 536                 if (sk->sk_state != DCCP_CLOSED)
 537                         err = -EISCONN;
 538                 else if (val < 0 || val >= DCCPQ_POLICY_MAX)
 539                         err = -EINVAL;
 540                 else
 541                         dp->dccps_qpolicy = val;
 542                 break;
 543         case DCCP_SOCKOPT_QPOLICY_TXQLEN:
 544                 if (val < 0)
 545                         err = -EINVAL;
 546                 else
 547                         dp->dccps_tx_qlen = val;
 548                 break;
 549         default:
 550                 err = -ENOPROTOOPT;
 551                 break;
 552         }
 553         release_sock(sk);
 554
 555         return err;
 556 }
 557
 558 int dccp_setsockopt(struct sock *sk, int level, int optname,
 559                     char __user *optval, unsigned int optlen)
 560 {
 561         if (level != SOL_DCCP)
 562                 return inet_csk(sk)->icsk_af_ops->setsockopt(sk, level,
 563                                                              optname, optval,
 564                                                              optlen);
 565         return do_dccp_setsockopt(sk, level, optname, optval, optlen);
 566 }
 567
 568 EXPORT_SYMBOL_GPL(dccp_setsockopt);
 569
 570 #ifdef CONFIG_COMPAT
 571 int compat_dccp_setsockopt(struct sock *sk, int level, int optname,
 572                            char __user *optval, unsigned int optlen)
 573 {
 574         if (level != SOL_DCCP)
 575                 return inet_csk_compat_setsockopt(sk, level, optname,
 576                                                   optval, optlen);
 577         return do_dccp_setsockopt(sk, level, optname, optval, optlen);
 578 }
 579
 580 EXPORT_SYMBOL_GPL(compat_dccp_setsockopt);
 581 #endif
 582
 583 static int dccp_getsockopt_service(struct sock *sk, int len,
 584                                    __be32 __user *optval,
 585                                    int __user *optlen)
 586 {
 587         const struct dccp_sock *dp = dccp_sk(sk);
 588         const struct dccp_service_list *sl;
 589         int err = -ENOENT, slen = 0, total_len = sizeof(u32);
 590
 591         lock_sock(sk);
 592         if ((sl = dp->dccps_service_list) != NULL) {
 593                 slen = sl->dccpsl_nr * sizeof(u32);
 594                 total_len += slen;
 595         }
 596
 597         err = -EINVAL;
 598         if (total_len > len)
 599                 goto out;
 600
 601         err = 0;
 602         if (put_user(total_len, optlen) ||
 603             put_user(dp->dccps_service, optval) ||
 604             (sl != NULL && copy_to_user(optval + 1, sl->dccpsl_list, slen)))
 605                 err = -EFAULT;
 606 out:
 607         release_sock(sk);
 608         return err;
 609 }
 610
 611 static int do_dccp_getsockopt(struct sock *sk, int level, int optname,
 612                     char __user *optval, int __user *optlen)
 613 {
 614         struct dccp_sock *dp;
 615         int val, len;
 616
 617         if (get_user(len, optlen))
 618                 return -EFAULT;
 619
 620         if (len < (int)sizeof(int))
 621                 return -EINVAL;
 622
 623         dp = dccp_sk(sk);
 624
 625         switch (optname) {
 626         case DCCP_SOCKOPT_PACKET_SIZE:
 627                 DCCP_WARN("sockopt(PACKET_SIZE) is deprecated: fix your app\n");
 628                 return 0;
 629         case DCCP_SOCKOPT_SERVICE:
 630                 return dccp_getsockopt_service(sk, len,
 631                                                (__be32 __user *)optval, optlen);
 632         case DCCP_SOCKOPT_GET_CUR_MPS:
 633                 val = dp->dccps_mss_cache;
 634                 break;
 635         case DCCP_SOCKOPT_AVAILABLE_CCIDS:
 636                 return ccid_getsockopt_builtin_ccids(sk, len, optval, optlen);
 637         case DCCP_SOCKOPT_TX_CCID:
 638                 val = ccid_get_current_tx_ccid(dp);
 639                 if (val < 0)
 640                         return -ENOPROTOOPT;
 641                 break;
 642         case DCCP_SOCKOPT_RX_CCID:
 643                 val = ccid_get_current_rx_ccid(dp);
 644                 if (val < 0)
 645                         return -ENOPROTOOPT;
 646                 break;
 647         case DCCP_SOCKOPT_SERVER_TIMEWAIT:
 648                 val = dp->dccps_server_timewait;
 649                 break;
 650         case DCCP_SOCKOPT_SEND_CSCOV:
 651                 val = dp->dccps_pcslen;
 652                 break;
 653         case DCCP_SOCKOPT_RECV_CSCOV:
 654                 val = dp->dccps_pcrlen;
 655                 break;
 656         case DCCP_SOCKOPT_QPOLICY_ID:
 657                 val = dp->dccps_qpolicy;
 658                 break;
 659         case DCCP_SOCKOPT_QPOLICY_TXQLEN:
 660                 val = dp->dccps_tx_qlen;
 661                 break;
 662         case 128 ... 191:
 663                 return ccid_hc_rx_getsockopt(dp->dccps_hc_rx_ccid, sk, optname,
 664                                              len, (u32 __user *)optval, optlen);
 665         case 192 ... 255:
 666                 return ccid_hc_tx_getsockopt(dp->dccps_hc_tx_ccid, sk, optname,
 667                                              len, (u32 __user *)optval, optlen);
 668         default:
 669                 return -ENOPROTOOPT;
 670         }
 671
 672         len = sizeof(val);
 673         if (put_user(len, optlen) || copy_to_user(optval, &val, len))
 674                 return -EFAULT;
 675
 676         return 0;
 677 }
 678
 679 int dccp_getsockopt(struct sock *sk, int level, int optname,
 680                     char __user *optval, int __user *optlen)
 681 {
 682         if (level != SOL_DCCP)
 683                 return inet_csk(sk)->icsk_af_ops->getsockopt(sk, level,
 684                                                              optname, optval,
 685                                                              optlen);
 686         return do_dccp_getsockopt(sk, level, optname, optval, optlen);
 687 }
 688
 689 EXPORT_SYMBOL_GPL(dccp_getsockopt);
 690
 691 #ifdef CONFIG_COMPAT
 692 int compat_dccp_getsockopt(struct sock *sk, int level, int optname,
 693                            char __user *optval, int __user *optlen)
 694 {
 695         if (level != SOL_DCCP)
 696                 return inet_csk_compat_getsockopt(sk, level, optname,
 697                                                   optval, optlen);
 698         return do_dccp_getsockopt(sk, level, optname, optval, optlen);
 699 }
 700
 701 EXPORT_SYMBOL_GPL(compat_dccp_getsockopt);
 702 #endif
 703
 704 static int dccp_msghdr_parse(struct msghdr *msg, struct sk_buff *skb)
 705 {
 706         struct cmsghdr *cmsg = CMSG_FIRSTHDR(msg);
 707
 708         /*
 709          * Assign an (opaque) qpolicy priority value to skb->priority.
 710          *
 711          * We are overloading this skb field for use with the qpolicy subystem.
 712          * The skb->priority is normally used for the SO_PRIORITY option, which
 713          * is initialised from sk_priority. Since the assignment of sk_priority
 714          * to skb->priority happens later (on layer 3), we overload this field
 715          * for use with queueing priorities as long as the skb is on layer 4.
 716          * The default priority value (if nothing is set) is 0.
 717          */
 718         skb->priority = 0;
 719
 720         for (; cmsg != NULL; cmsg = CMSG_NXTHDR(msg, cmsg)) {
 721
 722                 if (!CMSG_OK(msg, cmsg))
 723                         return -EINVAL;
 724
 725                 if (cmsg->cmsg_level != SOL_DCCP)
 726                         continue;
 727
 728                 if (cmsg->cmsg_type <= DCCP_SCM_QPOLICY_MAX &&
 729                     !dccp_qpolicy_param_ok(skb->sk, cmsg->cmsg_type))
 730                         return -EINVAL;
 731
 732                 switch (cmsg->cmsg_type) {
 733                 case DCCP_SCM_PRIORITY:
 734                         if (cmsg->cmsg_len != CMSG_LEN(sizeof(__u32)))
 735                                 return -EINVAL;
 736                         skb->priority = *(__u32 *)CMSG_DATA(cmsg);
 737                         break;
 738                 default:
 739                         return -EINVAL;
 740                 }
 741         }
 742         return 0;
 743 }
 744
 745 int dccp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 746                  size_t len)
 747 {
 748         const struct dccp_sock *dp = dccp_sk(sk);
 749         const int flags = msg->msg_flags;
 750         const int noblock = flags & MSG_DONTWAIT;
 751         struct sk_buff *skb;
 752         int rc, size;
 753         long timeo;
 754
 755         if (len > dp->dccps_mss_cache)
 756                 return -EMSGSIZE;
 757
 758         lock_sock(sk);
 759
 760         if (dccp_qpolicy_full(sk)) {
 761                 rc = -EAGAIN;
 762                 goto out_release;
 763         }
 764
 765         timeo = sock_sndtimeo(sk, noblock);
 766
 767         /*
 768          * We have to use sk_stream_wait_connect here to set sk_write_pending,
 769          * so that the trick in dccp_rcv_request_sent_state_process.
 770          */
 771         /* Wait for a connection to finish. */
 772         if ((1 << sk->sk_state) & ~(DCCPF_OPEN | DCCPF_PARTOPEN))
 773                 if ((rc = sk_stream_wait_connect(sk, &timeo)) != 0)
 774                         goto out_release;
 775
 776         size = sk->sk_prot->max_header + len;
 777         release_sock(sk);
 778         skb = sock_alloc_send_skb(sk, size, noblock, &rc);
 779         lock_sock(sk);
 780         if (skb == NULL)
 781                 goto out_release;
 782
 783         skb_reserve(skb, sk->sk_prot->max_header);
 784         rc = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
 785         if (rc != 0)
 786                 goto out_discard;
 787
 788         rc = dccp_msghdr_parse(msg, skb);
 789         if (rc != 0)
 790                 goto out_discard;
 791
 792         dccp_qpolicy_push(sk, skb);
 793         /*
 794          * The xmit_timer is set if the TX CCID is rate-based and will expire
 795          * when congestion control permits to release further packets into the
 796          * network. Window-based CCIDs do not use this timer.
 797          */
 798         if (!timer_pending(&dp->dccps_xmit_timer))
 799                 dccp_write_xmit(sk);
 800 out_release:
 801         release_sock(sk);
 802         return rc ? : len;
 803 out_discard:
 804         kfree_skb(skb);
 805         goto out_release;
 806 }
 807
 808 EXPORT_SYMBOL_GPL(dccp_sendmsg);
 809
 810 int dccp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 811                  size_t len, int nonblock, int flags, int *addr_len)
 812 {
 813         const struct dccp_hdr *dh;
 814         long timeo;
 815
 816         lock_sock(sk);
 817
 818         if (sk->sk_state == DCCP_LISTEN) {
 819                 len = -ENOTCONN;
 820                 goto out;
 821         }
 822
 823         timeo = sock_rcvtimeo(sk, nonblock);
 824
 825         do {
 826                 struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
 827
 828                 if (skb == NULL)
 829                         goto verify_sock_status;
 830
 831                 dh = dccp_hdr(skb);
 832
 833                 switch (dh->dccph_type) {
 834                 case DCCP_PKT_DATA:
 835                 case DCCP_PKT_DATAACK:
 836                         goto found_ok_skb;
 837
 838                 case DCCP_PKT_CLOSE:
 839                 case DCCP_PKT_CLOSEREQ:
 840                         if (!(flags & MSG_PEEK))
 841                                 dccp_finish_passive_close(sk);
 842                         /* fall through */
 843                 case DCCP_PKT_RESET:
 844                         dccp_pr_debug("found fin (%s) ok!\n",
 845                                       dccp_packet_name(dh->dccph_type));
 846                         len = 0;
 847                         goto found_fin_ok;
 848                 default:
 849                         dccp_pr_debug("packet_type=%s\n",
 850                                       dccp_packet_name(dh->dccph_type));
 851                         sk_eat_skb(sk, skb, 0);
 852                 }
 853 verify_sock_status:
 854                 if (sock_flag(sk, SOCK_DONE)) {
 855                         len = 0;
 856                         break;
 857                 }
 858
 859                 if (sk->sk_err) {
 860                         len = sock_error(sk);
 861                         break;
 862                 }
 863
 864                 if (sk->sk_shutdown & RCV_SHUTDOWN) {
 865                         len = 0;
 866                         break;
 867                 }
 868
 869                 if (sk->sk_state == DCCP_CLOSED) {
 870                         if (!sock_flag(sk, SOCK_DONE)) {
 871                                 /* This occurs when user tries to read
 872                                  * from never connected socket.
 873                                  */
 874                                 len = -ENOTCONN;
 875                                 break;
 876                         }
 877                         len = 0;
 878                         break;
 879                 }
 880
 881                 if (!timeo) {
 882                         len = -EAGAIN;
 883                         break;
 884                 }
 885
 886                 if (signal_pending(current)) {
 887                         len = sock_intr_errno(timeo);
 888                         break;
 889                 }
 890
 891                 sk_wait_data(sk, &timeo);
 892                 continue;
 893         found_ok_skb:
 894                 if (len > skb->len)
 895                         len = skb->len;
 896                 else if (len < skb->len)
 897                         msg->msg_flags |= MSG_TRUNC;
 898
 899                 if (skb_copy_datagram_iovec(skb, 0, msg->msg_iov, len)) {
 900                         /* Exception. Bailout! */
 901                         len = -EFAULT;
 902                         break;
 903                 }
 904                 if (flags & MSG_TRUNC)
 905                         len = skb->len;
 906         found_fin_ok:
 907                 if (!(flags & MSG_PEEK))
 908                         sk_eat_skb(sk, skb, 0);
 909                 break;
 910         } while (1);
 911 out:
 912         release_sock(sk);
 913         return len;
 914 }
 915
 916 EXPORT_SYMBOL_GPL(dccp_recvmsg);
 917
 918 int inet_dccp_listen(struct socket *sock, int backlog)
 919 {
 920         struct sock *sk = sock->sk;
 921         unsigned char old_state;
 922         int err;
 923
 924         lock_sock(sk);
 925
 926         err = -EINVAL;
 927         if (sock->state != SS_UNCONNECTED || sock->type != SOCK_DCCP)
 928                 goto out;
 929
 930         old_state = sk->sk_state;
 931         if (!((1 << old_state) & (DCCPF_CLOSED | DCCPF_LISTEN)))
 932                 goto out;
 933
 934         /* Really, if the socket is already in listen state
 935          * we can only allow the backlog to be adjusted.
 936          */
 937         if (old_state != DCCP_LISTEN) {
 938                 /*
 939                  * FIXME: here it probably should be sk->sk_prot->listen_start
 940                  * see tcp_listen_start
 941                  */
 942                 err = dccp_listen_start(sk, backlog);
 943                 if (err)
 944                         goto out;
 945         }
 946         sk->sk_max_ack_backlog = backlog;
 947         err = 0;
 948
 949 out:
 950         release_sock(sk);
 951         return err;
 952 }
 953
 954 EXPORT_SYMBOL_GPL(inet_dccp_listen);
 955
 956 static void dccp_terminate_connection(struct sock *sk)
 957 {
 958         u8 next_state = DCCP_CLOSED;
 959
 960         switch (sk->sk_state) {
 961         case DCCP_PASSIVE_CLOSE:
 962         case DCCP_PASSIVE_CLOSEREQ:
 963                 dccp_finish_passive_close(sk);
 964                 break;
 965         case DCCP_PARTOPEN:
 966                 dccp_pr_debug("Stop PARTOPEN timer (%p)\n", sk);
 967                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
 968                 /* fall through */
 969         case DCCP_OPEN:
 970                 dccp_send_close(sk, 1);
 971
 972                 if (dccp_sk(sk)->dccps_role == DCCP_ROLE_SERVER &&
 973                     !dccp_sk(sk)->dccps_server_timewait)
 974                         next_state = DCCP_ACTIVE_CLOSEREQ;
 975                 else
 976                         next_state = DCCP_CLOSING;
 977                 /* fall through */
 978         default:
 979                 dccp_set_state(sk, next_state);
 980         }
 981 }
 982
 983 void dccp_close(struct sock *sk, long timeout)
 984 {
 985         struct dccp_sock *dp = dccp_sk(sk);
 986         struct sk_buff *skb;
 987         u32 data_was_unread = 0;
 988         int state;
 989
 990         lock_sock(sk);
 991
 992         sk->sk_shutdown = SHUTDOWN_MASK;
 993
 994         if (sk->sk_state == DCCP_LISTEN) {
 995                 dccp_set_state(sk, DCCP_CLOSED);
 996
 997                 /* Special case. */
 998                 inet_csk_listen_stop(sk);
 999
1000                 goto adjudge_to_death;
1001         }
1002
1003         sk_stop_timer(sk, &dp->dccps_xmit_timer);
1004
1005         /*
1006          * We need to flush the recv. buffs.  We do this only on the
1007          * descriptor close, not protocol-sourced closes, because the
1008           *reader process may not have drained the data yet!
1009          */
1010         while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
1011                 data_was_unread += skb->len;
1012                 __kfree_skb(skb);
1013         }
1014
1015         if (data_was_unread) {
1016                 /* Unread data was tossed, send an appropriate Reset Code */
1017                 DCCP_WARN("ABORT with %u bytes unread\n", data_was_unread);
1018                 dccp_send_reset(sk, DCCP_RESET_CODE_ABORTED);
1019                 dccp_set_state(sk, DCCP_CLOSED);
1020         } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
1021                 /* Check zero linger _after_ checking for unread data. */
1022                 sk->sk_prot->disconnect(sk, 0);
1023         } else if (sk->sk_state != DCCP_CLOSED) {
1024                 /*
1025                  * Normal connection termination. May need to wait if there are
1026                  * still packets in the TX queue that are delayed by the CCID.
1027                  */
1028                 dccp_flush_write_queue(sk, &timeout);
1029                 dccp_terminate_connection(sk);
1030         }
1031
1032         /*
1033          * Flush write queue. This may be necessary in several cases:
1034          * - we have been closed by the peer but still have application data;
1035          * - abortive termination (unread data or zero linger time),
1036          * - normal termination but queue could not be flushed within time limit
1037          */
1038         __skb_queue_purge(&sk->sk_write_queue);
1039
1040         sk_stream_wait_close(sk, timeout);
1041
1042 adjudge_to_death:
1043         state = sk->sk_state;
1044         sock_hold(sk);
1045         sock_orphan(sk);
1046
1047         /*
1048          * It is the last release_sock in its life. It will remove backlog.
1049          */
1050         release_sock(sk);
1051         /*
1052          * Now socket is owned by kernel and we acquire BH lock
1053          * to finish close. No need to check for user refs.
1054          */
1055         local_bh_disable();
1056         bh_lock_sock(sk);
1057         WARN_ON(sock_owned_by_user(sk));
1058
1059         percpu_counter_inc(sk->sk_prot->orphan_count);
1060
1061         /* Have we already been destroyed by a softirq or backlog? */
1062         if (state != DCCP_CLOSED && sk->sk_state == DCCP_CLOSED)
1063                 goto out;
1064
1065         if (sk->sk_state == DCCP_CLOSED)
1066                 inet_csk_destroy_sock(sk);
1067
1068         /* Otherwise, socket is reprieved until protocol close. */
1069
1070 out:
1071         bh_unlock_sock(sk);
1072         local_bh_enable();
1073         sock_put(sk);
1074 }
1075
1076 EXPORT_SYMBOL_GPL(dccp_close);
1077
1078 void dccp_shutdown(struct sock *sk, int how)
1079 {
1080         dccp_pr_debug("called shutdown(%x)\n", how);
1081 }
1082
1083 EXPORT_SYMBOL_GPL(dccp_shutdown);
1084
1085 static inline int dccp_mib_init(void)
1086 {
1087         return snmp_mib_init((void __percpu **)dccp_statistics,
1088                              sizeof(struct dccp_mib),
1089                              __alignof__(struct dccp_mib));
1090 }
1091
1092 static inline void dccp_mib_exit(void)
1093 {
1094         snmp_mib_free((void __percpu **)dccp_statistics);
1095 }
1096
1097 static int thash_entries;
1098 module_param(thash_entries, int, 0444);
1099 MODULE_PARM_DESC(thash_entries, "Number of ehash buckets");
1100
1101 #ifdef CONFIG_IP_DCCP_DEBUG
1102 int dccp_debug;
1103 module_param(dccp_debug, bool, 0644);
1104 MODULE_PARM_DESC(dccp_debug, "Enable debug messages");
1105
1106 EXPORT_SYMBOL_GPL(dccp_debug);
1107 #endif
1108
1109 static int __init dccp_init(void)
1110 {
1111         unsigned long goal;
1112         int ehash_order, bhash_order, i;
1113         int rc;
1114
1115         BUILD_BUG_ON(sizeof(struct dccp_skb_cb) >
1116                      FIELD_SIZEOF(struct sk_buff, cb));
1117         rc = percpu_counter_init(&dccp_orphan_count, 0);
1118         if (rc)
1119                 goto out_fail;
1120         rc = -ENOBUFS;
1121         inet_hashinfo_init(&dccp_hashinfo);
1122         dccp_hashinfo.bind_bucket_cachep =
1123                 kmem_cache_create("dccp_bind_bucket",
1124                                   sizeof(struct inet_bind_bucket), 0,
1125                                   SLAB_HWCACHE_ALIGN, NULL);
1126         if (!dccp_hashinfo.bind_bucket_cachep)
1127                 goto out_free_percpu;
1128
1129         /*
1130          * Size and allocate the main established and bind bucket
1131          * hash tables.
1132          *
1133          * The methodology is similar to that of the buffer cache.
1134          */
1135         if (totalram_pages >= (128 * 1024))
1136                 goal = totalram_pages >> (21 - PAGE_SHIFT);
1137         else
1138                 goal = totalram_pages >> (23 - PAGE_SHIFT);
1139
1140         if (thash_entries)
1141                 goal = (thash_entries *
1142                         sizeof(struct inet_ehash_bucket)) >> PAGE_SHIFT;
1143         for (ehash_order = 0; (1UL << ehash_order) < goal; ehash_order++)
1144                 ;
1145         do {
1146                 unsigned long hash_size = (1UL << ehash_order) * PAGE_SIZE /
1147                                         sizeof(struct inet_ehash_bucket);
1148
1149                 while (hash_size & (hash_size - 1))
1150                         hash_size--;
1151                 dccp_hashinfo.ehash_mask = hash_size - 1;
1152                 dccp_hashinfo.ehash = (struct inet_ehash_bucket *)
1153                         __get_free_pages(GFP_ATOMIC|__GFP_NOWARN, ehash_order);
1154         } while (!dccp_hashinfo.ehash && --ehash_order > 0);
1155
1156         if (!dccp_hashinfo.ehash) {
1157                 DCCP_CRIT("Failed to allocate DCCP established hash table");
1158                 goto out_free_bind_bucket_cachep;
1159         }
1160
1161         for (i = 0; i <= dccp_hashinfo.ehash_mask; i++) {
1162                 INIT_HLIST_NULLS_HEAD(&dccp_hashinfo.ehash[i].chain, i);
1163                 INIT_HLIST_NULLS_HEAD(&dccp_hashinfo.ehash[i].twchain, i);
1164         }
1165
1166         if (inet_ehash_locks_alloc(&dccp_hashinfo))
1167                         goto out_free_dccp_ehash;
1168
1169         bhash_order = ehash_order;
1170
1171         do {
1172                 dccp_hashinfo.bhash_size = (1UL << bhash_order) * PAGE_SIZE /
1173                                         sizeof(struct inet_bind_hashbucket);
1174                 if ((dccp_hashinfo.bhash_size > (64 * 1024)) &&
1175                     bhash_order > 0)
1176                         continue;
1177                 dccp_hashinfo.bhash = (struct inet_bind_hashbucket *)
1178                         __get_free_pages(GFP_ATOMIC|__GFP_NOWARN, bhash_order);
1179         } while (!dccp_hashinfo.bhash && --bhash_order >= 0);
1180
1181         if (!dccp_hashinfo.bhash) {
1182                 DCCP_CRIT("Failed to allocate DCCP bind hash table");
1183                 goto out_free_dccp_locks;
1184         }
1185
1186         for (i = 0; i < dccp_hashinfo.bhash_size; i++) {
1187                 spin_lock_init(&dccp_hashinfo.bhash[i].lock);
1188                 INIT_HLIST_HEAD(&dccp_hashinfo.bhash[i].chain);
1189         }
1190
1191         rc = dccp_mib_init();
1192         if (rc)
1193                 goto out_free_dccp_bhash;
1194
1195         rc = dccp_ackvec_init();
1196         if (rc)
1197                 goto out_free_dccp_mib;
1198
1199         rc = dccp_sysctl_init();
1200         if (rc)
1201                 goto out_ackvec_exit;
1202
1203         rc = ccid_initialize_builtins();
1204         if (rc)
1205                 goto out_sysctl_exit;
1206
1207         dccp_timestamping_init();
1208
1209         return 0;
1210
1211 out_sysctl_exit:
1212         dccp_sysctl_exit();
1213 out_ackvec_exit:
1214         dccp_ackvec_exit();
1215 out_free_dccp_mib:
1216         dccp_mib_exit();
1217 out_free_dccp_bhash:
1218         free_pages((unsigned long)dccp_hashinfo.bhash, bhash_order);
1219 out_free_dccp_locks:
1220         inet_ehash_locks_free(&dccp_hashinfo);
1221 out_free_dccp_ehash:
1222         free_pages((unsigned long)dccp_hashinfo.ehash, ehash_order);
1223 out_free_bind_bucket_cachep:
1224         kmem_cache_destroy(dccp_hashinfo.bind_bucket_cachep);
1225 out_free_percpu:
1226         percpu_counter_destroy(&dccp_orphan_count);
1227 out_fail:
1228         dccp_hashinfo.bhash = NULL;
1229         dccp_hashinfo.ehash = NULL;
1230         dccp_hashinfo.bind_bucket_cachep = NULL;
1231         return rc;
1232 }
1233
1234 static void __exit dccp_fini(void)
1235 {
1236         ccid_cleanup_builtins();
1237         dccp_mib_exit();
1238         free_pages((unsigned long)dccp_hashinfo.bhash,
1239                    get_order(dccp_hashinfo.bhash_size *
1240                              sizeof(struct inet_bind_hashbucket)));
1241         free_pages((unsigned long)dccp_hashinfo.ehash,
1242                    get_order((dccp_hashinfo.ehash_mask + 1) *
1243                              sizeof(struct inet_ehash_bucket)));
1244         inet_ehash_locks_free(&dccp_hashinfo);
1245         kmem_cache_destroy(dccp_hashinfo.bind_bucket_cachep);
1246         dccp_ackvec_exit();
1247         dccp_sysctl_exit();
1248         percpu_counter_destroy(&dccp_orphan_count);
1249 }
1250
1251 module_init(dccp_init);
1252 module_exit(dccp_fini);
1253
1254 MODULE_LICENSE("GPL");
1255 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@conectiva.com.br>");
1256 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");