net/dccp/output.c

   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/config.h>
  14 #include <linux/dccp.h>
  15 #include <linux/kernel.h>
  16 #include <linux/skbuff.h>
  17
  18 #include <net/inet_sock.h>
  19 #include <net/sock.h>
  20
  21 #include "ackvec.h"
  22 #include "ccid.h"
  23 #include "dccp.h"
  24
  25 static inline void dccp_event_ack_sent(struct sock *sk)
  26 {
  27         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
  28 }
  29
  30 static inline void dccp_skb_entail(struct sock *sk, struct sk_buff *skb)
  31 {
  32         skb_set_owner_w(skb, sk);
  33         WARN_ON(sk->sk_send_head);
  34         sk->sk_send_head = skb;
  35 }
  36
  37 /*
  38  * All SKB's seen here are completely headerless. It is our
  39  * job to build the DCCP header, and pass the packet down to
  40  * IP so it can do the same plus pass the packet off to the
  41  * device.
  42  */
  43 static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb)
  44 {
  45         if (likely(skb != NULL)) {
  46                 const struct inet_sock *inet = inet_sk(sk);
  47                 const struct inet_connection_sock *icsk = inet_csk(sk);
  48                 struct dccp_sock *dp = dccp_sk(sk);
  49                 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
  50                 struct dccp_hdr *dh;
  51                 /* XXX For now we're using only 48 bits sequence numbers */
  52                 const int dccp_header_size = sizeof(*dh) +
  53                                              sizeof(struct dccp_hdr_ext) +
  54                                           dccp_packet_hdr_len(dcb->dccpd_type);
  55                 int err, set_ack = 1;
  56                 u64 ackno = dp->dccps_gsr;
  57
  58                 dccp_inc_seqno(&dp->dccps_gss);
  59
  60                 switch (dcb->dccpd_type) {
  61                 case DCCP_PKT_DATA:
  62                         set_ack = 0;
  63                         /* fall through */
  64                 case DCCP_PKT_DATAACK:
  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_seq;
  74                         /* fall through */
  75                 default:
  76                         /*
  77                          * Only data packets should come through with skb->sk
  78                          * set.
  79                          */
  80                         WARN_ON(skb->sk);
  81                         skb_set_owner_w(skb, sk);
  82                         break;
  83                 }
  84
  85                 dcb->dccpd_seq = dp->dccps_gss;
  86                 dccp_insert_options(sk, skb);
  87
  88                 skb->h.raw = skb_push(skb, dccp_header_size);
  89                 dh = dccp_hdr(skb);
  90
  91                 /* Build DCCP header and checksum it. */
  92                 memset(dh, 0, dccp_header_size);
  93                 dh->dccph_type  = dcb->dccpd_type;
  94                 dh->dccph_sport = inet->sport;
  95                 dh->dccph_dport = inet->dport;
  96                 dh->dccph_doff  = (dccp_header_size + dcb->dccpd_opt_len) / 4;
  97                 dh->dccph_ccval = dcb->dccpd_ccval;
  98                 /* XXX For now we're using only 48 bits sequence numbers */
  99                 dh->dccph_x     = 1;
 100
 101                 dp->dccps_awh = dp->dccps_gss;
 102                 dccp_hdr_set_seq(dh, dp->dccps_gss);
 103                 if (set_ack)
 104                         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
 105
 106                 switch (dcb->dccpd_type) {
 107                 case DCCP_PKT_REQUEST:
 108                         dccp_hdr_request(skb)->dccph_req_service =
 109                                                         dp->dccps_service;
 110                         break;
 111                 case DCCP_PKT_RESET:
 112                         dccp_hdr_reset(skb)->dccph_reset_code =
 113                                                         dcb->dccpd_reset_code;
 114                         break;
 115                 }
 116
 117                 icsk->icsk_af_ops->send_check(sk, skb->len, skb);
 118
 119                 if (set_ack)
 120                         dccp_event_ack_sent(sk);
 121
 122                 DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
 123
 124                 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 125                 err = icsk->icsk_af_ops->queue_xmit(skb, 0);
 126                 if (err <= 0)
 127                         return err;
 128
 129                 /* NET_XMIT_CN is special. It does not guarantee,
 130                  * that this packet is lost. It tells that device
 131                  * is about to start to drop packets or already
 132                  * drops some packets of the same priority and
 133                  * invokes us to send less aggressively.
 134                  */
 135                 return err == NET_XMIT_CN ? 0 : err;
 136         }
 137         return -ENOBUFS;
 138 }
 139
 140 unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
 141 {
 142         struct inet_connection_sock *icsk = inet_csk(sk);
 143         struct dccp_sock *dp = dccp_sk(sk);
 144         int mss_now = (pmtu - icsk->icsk_af_ops->net_header_len -
 145                        sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext));
 146
 147         /* Now subtract optional transport overhead */
 148         mss_now -= icsk->icsk_ext_hdr_len;
 149
 150         /*
 151          * FIXME: this should come from the CCID infrastructure, where, say,
 152          * TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
 153          * put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
 154          * TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
 155          * make it a multiple of 4
 156          */
 157
 158         mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
 159
 160         /* And store cached results */
 161         icsk->icsk_pmtu_cookie = pmtu;
 162         dp->dccps_mss_cache = mss_now;
 163
 164         return mss_now;
 165 }
 166
 167 EXPORT_SYMBOL_GPL(dccp_sync_mss);
 168
 169 void dccp_write_space(struct sock *sk)
 170 {
 171         read_lock(&sk->sk_callback_lock);
 172
 173         if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
 174                 wake_up_interruptible(sk->sk_sleep);
 175         /* Should agree with poll, otherwise some programs break */
 176         if (sock_writeable(sk))
 177                 sk_wake_async(sk, 2, POLL_OUT);
 178
 179         read_unlock(&sk->sk_callback_lock);
 180 }
 181
 182 /**
 183  * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
 184  * @sk: socket to wait for
 185  * @timeo: for how long
 186  */
 187 static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb,
 188                               long *timeo)
 189 {
 190         struct dccp_sock *dp = dccp_sk(sk);
 191         DEFINE_WAIT(wait);
 192         long delay;
 193         int rc;
 194
 195         while (1) {
 196                 prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
 197
 198                 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 199                         goto do_error;
 200                 if (!*timeo)
 201                         goto do_nonblock;
 202                 if (signal_pending(current))
 203                         goto do_interrupted;
 204
 205                 rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
 206                                             skb->len);
 207                 if (rc <= 0)
 208                         break;
 209                 delay = msecs_to_jiffies(rc);
 210                 if (delay > *timeo || delay < 0)
 211                         goto do_nonblock;
 212
 213                 sk->sk_write_pending++;
 214                 release_sock(sk);
 215                 *timeo -= schedule_timeout(delay);
 216                 lock_sock(sk);
 217                 sk->sk_write_pending--;
 218         }
 219 out:
 220         finish_wait(sk->sk_sleep, &wait);
 221         return rc;
 222
 223 do_error:
 224         rc = -EPIPE;
 225         goto out;
 226 do_nonblock:
 227         rc = -EAGAIN;
 228         goto out;
 229 do_interrupted:
 230         rc = sock_intr_errno(*timeo);
 231         goto out;
 232 }
 233
 234 int dccp_write_xmit(struct sock *sk, struct sk_buff *skb, long *timeo)
 235 {
 236         const struct dccp_sock *dp = dccp_sk(sk);
 237         int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
 238                                          skb->len);
 239
 240         if (err > 0)
 241                 err = dccp_wait_for_ccid(sk, skb, timeo);
 242
 243         if (err == 0) {
 244                 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 245                 const int len = skb->len;
 246
 247                 if (sk->sk_state == DCCP_PARTOPEN) {
 248                         /* See 8.1.5.  Handshake Completion */
 249                         inet_csk_schedule_ack(sk);
 250                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
 251                                                   inet_csk(sk)->icsk_rto,
 252                                                   DCCP_RTO_MAX);
 253                         dcb->dccpd_type = DCCP_PKT_DATAACK;
 254                 } else if (dccp_ack_pending(sk))
 255                         dcb->dccpd_type = DCCP_PKT_DATAACK;
 256                 else
 257                         dcb->dccpd_type = DCCP_PKT_DATA;
 258
 259                 err = dccp_transmit_skb(sk, skb);
 260                 ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len);
 261         } else
 262                 kfree_skb(skb);
 263
 264         return err;
 265 }
 266
 267 int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
 268 {
 269         if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk) != 0)
 270                 return -EHOSTUNREACH; /* Routing failure or similar. */
 271
 272         return dccp_transmit_skb(sk, (skb_cloned(skb) ?
 273                                       pskb_copy(skb, GFP_ATOMIC):
 274                                       skb_clone(skb, GFP_ATOMIC)));
 275 }
 276
 277 struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
 278                                    struct request_sock *req)
 279 {
 280         struct dccp_hdr *dh;
 281         struct dccp_request_sock *dreq;
 282         const int dccp_header_size = sizeof(struct dccp_hdr) +
 283                                      sizeof(struct dccp_hdr_ext) +
 284                                      sizeof(struct dccp_hdr_response);
 285         struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
 286                                                dccp_header_size, 1,
 287                                            GFP_ATOMIC);
 288         if (skb == NULL)
 289                 return NULL;
 290
 291         /* Reserve space for headers. */
 292         skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
 293
 294         skb->dst = dst_clone(dst);
 295         skb->csum = 0;
 296
 297         dreq = dccp_rsk(req);
 298         DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
 299         DCCP_SKB_CB(skb)->dccpd_seq  = dreq->dreq_iss;
 300         dccp_insert_options(sk, skb);
 301
 302         skb->h.raw = skb_push(skb, dccp_header_size);
 303
 304         dh = dccp_hdr(skb);
 305         memset(dh, 0, dccp_header_size);
 306
 307         dh->dccph_sport = inet_sk(sk)->sport;
 308         dh->dccph_dport = inet_rsk(req)->rmt_port;
 309         dh->dccph_doff  = (dccp_header_size +
 310                            DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
 311         dh->dccph_type  = DCCP_PKT_RESPONSE;
 312         dh->dccph_x     = 1;
 313         dccp_hdr_set_seq(dh, dreq->dreq_iss);
 314         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_isr);
 315         dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service;
 316
 317         dh->dccph_checksum = dccp_v4_checksum(skb, inet_rsk(req)->loc_addr,
 318                                               inet_rsk(req)->rmt_addr);
 319
 320         DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
 321         return skb;
 322 }
 323
 324 EXPORT_SYMBOL_GPL(dccp_make_response);
 325
 326 struct sk_buff *dccp_make_reset(struct sock *sk, struct dst_entry *dst,
 327                                 const enum dccp_reset_codes code)
 328
 329 {
 330         struct dccp_hdr *dh;
 331         struct dccp_sock *dp = dccp_sk(sk);
 332         const int dccp_header_size = sizeof(struct dccp_hdr) +
 333                                      sizeof(struct dccp_hdr_ext) +
 334                                      sizeof(struct dccp_hdr_reset);
 335         struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
 336                                                dccp_header_size, 1,
 337                                            GFP_ATOMIC);
 338         if (skb == NULL)
 339                 return NULL;
 340
 341         /* Reserve space for headers. */
 342         skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
 343
 344         skb->dst = dst_clone(dst);
 345         skb->csum = 0;
 346
 347         dccp_inc_seqno(&dp->dccps_gss);
 348
 349         DCCP_SKB_CB(skb)->dccpd_reset_code = code;
 350         DCCP_SKB_CB(skb)->dccpd_type       = DCCP_PKT_RESET;
 351         DCCP_SKB_CB(skb)->dccpd_seq        = dp->dccps_gss;
 352         dccp_insert_options(sk, skb);
 353
 354         skb->h.raw = skb_push(skb, dccp_header_size);
 355
 356         dh = dccp_hdr(skb);
 357         memset(dh, 0, dccp_header_size);
 358
 359         dh->dccph_sport = inet_sk(sk)->sport;
 360         dh->dccph_dport = inet_sk(sk)->dport;
 361         dh->dccph_doff  = (dccp_header_size +
 362                            DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
 363         dh->dccph_type  = DCCP_PKT_RESET;
 364         dh->dccph_x     = 1;
 365         dccp_hdr_set_seq(dh, dp->dccps_gss);
 366         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr);
 367
 368         dccp_hdr_reset(skb)->dccph_reset_code = code;
 369
 370         dh->dccph_checksum = dccp_v4_checksum(skb, inet_sk(sk)->saddr,
 371                                               inet_sk(sk)->daddr);
 372
 373         DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
 374         return skb;
 375 }
 376
 377 /*
 378  * Do all connect socket setups that can be done AF independent.
 379  */
 380 static inline void dccp_connect_init(struct sock *sk)
 381 {
 382         struct dccp_sock *dp = dccp_sk(sk);
 383         struct dst_entry *dst = __sk_dst_get(sk);
 384         struct inet_connection_sock *icsk = inet_csk(sk);
 385
 386         sk->sk_err = 0;
 387         sock_reset_flag(sk, SOCK_DONE);
 388
 389         dccp_sync_mss(sk, dst_mtu(dst));
 390
 391         dccp_update_gss(sk, dp->dccps_iss);
 392         /*
 393          * SWL and AWL are initially adjusted so that they are not less than
 394          * the initial Sequence Numbers received and sent, respectively:
 395          *      SWL := max(GSR + 1 - floor(W/4), ISR),
 396          *      AWL := max(GSS - W' + 1, ISS).
 397          * These adjustments MUST be applied only at the beginning of the
 398          * connection.
 399          */
 400         dccp_set_seqno(&dp->dccps_awl, max48(dp->dccps_awl, dp->dccps_iss));
 401
 402         icsk->icsk_retransmits = 0;
 403 }
 404
 405 int dccp_connect(struct sock *sk)
 406 {
 407         struct sk_buff *skb;
 408         struct inet_connection_sock *icsk = inet_csk(sk);
 409
 410         dccp_connect_init(sk);
 411
 412         skb = alloc_skb(MAX_DCCP_HEADER + 15, sk->sk_allocation);
 413         if (unlikely(skb == NULL))
 414                 return -ENOBUFS;
 415
 416         /* Reserve space for headers. */
 417         skb_reserve(skb, MAX_DCCP_HEADER);
 418
 419         DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
 420         skb->csum = 0;
 421
 422         dccp_skb_entail(sk, skb);
 423         dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL));
 424         DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);
 425
 426         /* Timer for repeating the REQUEST until an answer. */
 427         inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
 428                                   icsk->icsk_rto, DCCP_RTO_MAX);
 429         return 0;
 430 }
 431
 432 EXPORT_SYMBOL_GPL(dccp_connect);
 433
 434 void dccp_send_ack(struct sock *sk)
 435 {
 436         /* If we have been reset, we may not send again. */
 437         if (sk->sk_state != DCCP_CLOSED) {
 438                 struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
 439
 440                 if (skb == NULL) {
 441                         inet_csk_schedule_ack(sk);
 442                         inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
 443                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
 444                                                   TCP_DELACK_MAX,
 445                                                   DCCP_RTO_MAX);
 446                         return;
 447                 }
 448
 449                 /* Reserve space for headers */
 450                 skb_reserve(skb, MAX_DCCP_HEADER);
 451                 skb->csum = 0;
 452                 DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
 453                 dccp_transmit_skb(sk, skb);
 454         }
 455 }
 456
 457 EXPORT_SYMBOL_GPL(dccp_send_ack);
 458
 459 void dccp_send_delayed_ack(struct sock *sk)
 460 {
 461         struct inet_connection_sock *icsk = inet_csk(sk);
 462         /*
 463          * FIXME: tune this timer. elapsed time fixes the skew, so no problem
 464          * with using 2s, and active senders also piggyback the ACK into a
 465          * DATAACK packet, so this is really for quiescent senders.
 466          */
 467         unsigned long timeout = jiffies + 2 * HZ;
 468
 469         /* Use new timeout only if there wasn't a older one earlier. */
 470         if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
 471                 /* If delack timer was blocked or is about to expire,
 472                  * send ACK now.
 473                  *
 474                  * FIXME: check the "about to expire" part
 475                  */
 476                 if (icsk->icsk_ack.blocked) {
 477                         dccp_send_ack(sk);
 478                         return;
 479                 }
 480
 481                 if (!time_before(timeout, icsk->icsk_ack.timeout))
 482                         timeout = icsk->icsk_ack.timeout;
 483         }
 484         icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
 485         icsk->icsk_ack.timeout = timeout;
 486         sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
 487 }
 488
 489 void dccp_send_sync(struct sock *sk, const u64 seq,
 490                     const enum dccp_pkt_type pkt_type)
 491 {
 492         /*
 493          * We are not putting this on the write queue, so
 494          * dccp_transmit_skb() will set the ownership to this
 495          * sock.
 496          */
 497         struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
 498
 499         if (skb == NULL)
 500                 /* FIXME: how to make sure the sync is sent? */
 501                 return;
 502
 503         /* Reserve space for headers and prepare control bits. */
 504         skb_reserve(skb, MAX_DCCP_HEADER);
 505         skb->csum = 0;
 506         DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
 507         DCCP_SKB_CB(skb)->dccpd_seq = seq;
 508
 509         dccp_transmit_skb(sk, skb);
 510 }
 511
 512 /*
 513  * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
 514  * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
 515  * any circumstances.
 516  */
 517 void dccp_send_close(struct sock *sk, const int active)
 518 {
 519         struct dccp_sock *dp = dccp_sk(sk);
 520         struct sk_buff *skb;
 521         const gfp_t prio = active ? GFP_KERNEL : GFP_ATOMIC;
 522
 523         skb = alloc_skb(sk->sk_prot->max_header, prio);
 524         if (skb == NULL)
 525                 return;
 526
 527         /* Reserve space for headers and prepare control bits. */
 528         skb_reserve(skb, sk->sk_prot->max_header);
 529         skb->csum = 0;
 530         DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ?
 531                                         DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ;
 532
 533         if (active) {
 534                 dccp_skb_entail(sk, skb);
 535                 dccp_transmit_skb(sk, skb_clone(skb, prio));
 536         } else
 537                 dccp_transmit_skb(sk, skb);
 538 }