net/batman-adv/tp_meter.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (C) B.A.T.M.A.N. contributors:
   3  *
   4  * Edo Monticelli, Antonio Quartulli
   5  */
   6
   7 #include "tp_meter.h"
   8 #include "main.h"
   9
  10 #include <linux/atomic.h>
  11 #include <linux/build_bug.h>
  12 #include <linux/byteorder/generic.h>
  13 #include <linux/cache.h>
  14 #include <linux/compiler.h>
  15 #include <linux/container_of.h>
  16 #include <linux/err.h>
  17 #include <linux/etherdevice.h>
  18 #include <linux/gfp.h>
  19 #include <linux/if_ether.h>
  20 #include <linux/init.h>
  21 #include <linux/jiffies.h>
  22 #include <linux/kref.h>
  23 #include <linux/kthread.h>
  24 #include <linux/limits.h>
  25 #include <linux/list.h>
  26 #include <linux/minmax.h>
  27 #include <linux/netdevice.h>
  28 #include <linux/param.h>
  29 #include <linux/printk.h>
  30 #include <linux/random.h>
  31 #include <linux/rculist.h>
  32 #include <linux/rcupdate.h>
  33 #include <linux/sched.h>
  34 #include <linux/skbuff.h>
  35 #include <linux/slab.h>
  36 #include <linux/spinlock.h>
  37 #include <linux/stddef.h>
  38 #include <linux/string.h>
  39 #include <linux/timer.h>
  40 #include <linux/wait.h>
  41 #include <linux/workqueue.h>
  42 #include <uapi/linux/batadv_packet.h>
  43 #include <uapi/linux/batman_adv.h>
  44
  45 #include "hard-interface.h"
  46 #include "log.h"
  47 #include "netlink.h"
  48 #include "originator.h"
  49 #include "send.h"
  50
  51 /**
  52  * BATADV_TP_DEF_TEST_LENGTH - Default test length if not specified by the user
  53  *  in milliseconds
  54  */
  55 #define BATADV_TP_DEF_TEST_LENGTH 10000
  56
  57 /**
  58  * BATADV_TP_AWND - Advertised window by the receiver (in bytes)
  59  */
  60 #define BATADV_TP_AWND 0x20000000
  61
  62 /**
  63  * BATADV_TP_RECV_TIMEOUT - Receiver activity timeout. If the receiver does not
  64  *  get anything for such amount of milliseconds, the connection is killed
  65  */
  66 #define BATADV_TP_RECV_TIMEOUT 1000
  67
  68 /**
  69  * BATADV_TP_MAX_RTO - Maximum sender timeout. If the sender RTO gets beyond
  70  * such amount of milliseconds, the receiver is considered unreachable and the
  71  * connection is killed
  72  */
  73 #define BATADV_TP_MAX_RTO 30000
  74
  75 /**
  76  * BATADV_TP_FIRST_SEQ - First seqno of each session. The number is rather high
  77  *  in order to immediately trigger a wrap around (test purposes)
  78  */
  79 #define BATADV_TP_FIRST_SEQ ((u32)-1 - 2000)
  80
  81 /**
  82  * BATADV_TP_PLEN - length of the payload (data after the batadv_unicast header)
  83  *  to simulate
  84  */
  85 #define BATADV_TP_PLEN (BATADV_TP_PACKET_LEN - ETH_HLEN - \
  86                         sizeof(struct batadv_unicast_packet))
  87
  88 static u8 batadv_tp_prerandom[4096] __read_mostly;
  89
  90 /**
  91  * batadv_tp_session_cookie() - generate session cookie based on session ids
  92  * @session: TP session identifier
  93  * @icmp_uid: icmp pseudo uid of the tp session
  94  *
  95  * Return: 32 bit tp_meter session cookie
  96  */
  97 static u32 batadv_tp_session_cookie(const u8 session[2], u8 icmp_uid)
  98 {
  99         u32 cookie;
 100
 101         cookie = icmp_uid << 16;
 102         cookie |= session[0] << 8;
 103         cookie |= session[1];
 104
 105         return cookie;
 106 }
 107
 108 /**
 109  * batadv_tp_cwnd() - compute the new cwnd size
 110  * @base: base cwnd size value
 111  * @increment: the value to add to base to get the new size
 112  * @min: minimum cwnd value (usually MSS)
 113  *
 114  * Return the new cwnd size and ensure it does not exceed the Advertised
 115  * Receiver Window size. It is wrapped around safely.
 116  * For details refer to Section 3.1 of RFC5681
 117  *
 118  * Return: new congestion window size in bytes
 119  */
 120 static u32 batadv_tp_cwnd(u32 base, u32 increment, u32 min)
 121 {
 122         u32 new_size = base + increment;
 123
 124         /* check for wrap-around */
 125         if (new_size < base)
 126                 new_size = (u32)ULONG_MAX;
 127
 128         new_size = min_t(u32, new_size, BATADV_TP_AWND);
 129
 130         return max_t(u32, new_size, min);
 131 }
 132
 133 /**
 134  * batadv_tp_update_cwnd() - update the Congestion Windows
 135  * @tp_vars: the private data of the current TP meter session
 136  * @mss: maximum segment size of transmission
 137  *
 138  * 1) if the session is in Slow Start, the CWND has to be increased by 1
 139  * MSS every unique received ACK
 140  * 2) if the session is in Congestion Avoidance, the CWND has to be
 141  * increased by MSS * MSS / CWND for every unique received ACK
 142  */
 143 static void batadv_tp_update_cwnd(struct batadv_tp_vars *tp_vars, u32 mss)
 144 {
 145         spin_lock_bh(&tp_vars->cwnd_lock);
 146
 147         /* slow start... */
 148         if (tp_vars->cwnd <= tp_vars->ss_threshold) {
 149                 tp_vars->dec_cwnd = 0;
 150                 tp_vars->cwnd = batadv_tp_cwnd(tp_vars->cwnd, mss, mss);
 151                 spin_unlock_bh(&tp_vars->cwnd_lock);
 152                 return;
 153         }
 154
 155         /* increment CWND at least of 1 (section 3.1 of RFC5681) */
 156         tp_vars->dec_cwnd += max_t(u32, 1U << 3,
 157                                    ((mss * mss) << 6) / (tp_vars->cwnd << 3));
 158         if (tp_vars->dec_cwnd < (mss << 3)) {
 159                 spin_unlock_bh(&tp_vars->cwnd_lock);
 160                 return;
 161         }
 162
 163         tp_vars->cwnd = batadv_tp_cwnd(tp_vars->cwnd, mss, mss);
 164         tp_vars->dec_cwnd = 0;
 165
 166         spin_unlock_bh(&tp_vars->cwnd_lock);
 167 }
 168
 169 /**
 170  * batadv_tp_update_rto() - calculate new retransmission timeout
 171  * @tp_vars: the private data of the current TP meter session
 172  * @new_rtt: new roundtrip time in msec
 173  */
 174 static void batadv_tp_update_rto(struct batadv_tp_vars *tp_vars,
 175                                  u32 new_rtt)
 176 {
 177         long m = new_rtt;
 178
 179         /* RTT update
 180          * Details in Section 2.2 and 2.3 of RFC6298
 181          *
 182          * It's tricky to understand. Don't lose hair please.
 183          * Inspired by tcp_rtt_estimator() tcp_input.c
 184          */
 185         if (tp_vars->srtt != 0) {
 186                 m -= (tp_vars->srtt >> 3); /* m is now error in rtt est */
 187                 tp_vars->srtt += m; /* rtt = 7/8 srtt + 1/8 new */
 188                 if (m < 0)
 189                         m = -m;
 190
 191                 m -= (tp_vars->rttvar >> 2);
 192                 tp_vars->rttvar += m; /* mdev ~= 3/4 rttvar + 1/4 new */
 193         } else {
 194                 /* first measure getting in */
 195                 tp_vars->srtt = m << 3; /* take the measured time to be srtt */
 196                 tp_vars->rttvar = m << 1; /* new_rtt / 2 */
 197         }
 198
 199         /* rto = srtt + 4 * rttvar.
 200          * rttvar is scaled by 4, therefore doesn't need to be multiplied
 201          */
 202         tp_vars->rto = (tp_vars->srtt >> 3) + tp_vars->rttvar;
 203 }
 204
 205 /**
 206  * batadv_tp_batctl_notify() - send client status result to client
 207  * @reason: reason for tp meter session stop
 208  * @dst: destination of tp_meter session
 209  * @bat_priv: the bat priv with all the soft interface information
 210  * @start_time: start of transmission in jiffies
 211  * @total_sent: bytes acked to the receiver
 212  * @cookie: cookie of tp_meter session
 213  */
 214 static void batadv_tp_batctl_notify(enum batadv_tp_meter_reason reason,
 215                                     const u8 *dst, struct batadv_priv *bat_priv,
 216                                     unsigned long start_time, u64 total_sent,
 217                                     u32 cookie)
 218 {
 219         u32 test_time;
 220         u8 result;
 221         u32 total_bytes;
 222
 223         if (!batadv_tp_is_error(reason)) {
 224                 result = BATADV_TP_REASON_COMPLETE;
 225                 test_time = jiffies_to_msecs(jiffies - start_time);
 226                 total_bytes = total_sent;
 227         } else {
 228                 result = reason;
 229                 test_time = 0;
 230                 total_bytes = 0;
 231         }
 232
 233         batadv_netlink_tpmeter_notify(bat_priv, dst, result, test_time,
 234                                       total_bytes, cookie);
 235 }
 236
 237 /**
 238  * batadv_tp_batctl_error_notify() - send client error result to client
 239  * @reason: reason for tp meter session stop
 240  * @dst: destination of tp_meter session
 241  * @bat_priv: the bat priv with all the soft interface information
 242  * @cookie: cookie of tp_meter session
 243  */
 244 static void batadv_tp_batctl_error_notify(enum batadv_tp_meter_reason reason,
 245                                           const u8 *dst,
 246                                           struct batadv_priv *bat_priv,
 247                                           u32 cookie)
 248 {
 249         batadv_tp_batctl_notify(reason, dst, bat_priv, 0, 0, cookie);
 250 }
 251
 252 /**
 253  * batadv_tp_list_find() - find a tp_vars object in the global list
 254  * @bat_priv: the bat priv with all the soft interface information
 255  * @dst: the other endpoint MAC address to look for
 256  *
 257  * Look for a tp_vars object matching dst as end_point and return it after
 258  * having increment the refcounter. Return NULL is not found
 259  *
 260  * Return: matching tp_vars or NULL when no tp_vars with @dst was found
 261  */
 262 static struct batadv_tp_vars *batadv_tp_list_find(struct batadv_priv *bat_priv,
 263                                                   const u8 *dst)
 264 {
 265         struct batadv_tp_vars *pos, *tp_vars = NULL;
 266
 267         rcu_read_lock();
 268         hlist_for_each_entry_rcu(pos, &bat_priv->tp_list, list) {
 269                 if (!batadv_compare_eth(pos->other_end, dst))
 270                         continue;
 271
 272                 /* most of the time this function is invoked during the normal
 273                  * process..it makes sens to pay more when the session is
 274                  * finished and to speed the process up during the measurement
 275                  */
 276                 if (unlikely(!kref_get_unless_zero(&pos->refcount)))
 277                         continue;
 278
 279                 tp_vars = pos;
 280                 break;
 281         }
 282         rcu_read_unlock();
 283
 284         return tp_vars;
 285 }
 286
 287 /**
 288  * batadv_tp_list_find_session() - find tp_vars session object in the global
 289  *  list
 290  * @bat_priv: the bat priv with all the soft interface information
 291  * @dst: the other endpoint MAC address to look for
 292  * @session: session identifier
 293  *
 294  * Look for a tp_vars object matching dst as end_point, session as tp meter
 295  * session and return it after having increment the refcounter. Return NULL
 296  * is not found
 297  *
 298  * Return: matching tp_vars or NULL when no tp_vars was found
 299  */
 300 static struct batadv_tp_vars *
 301 batadv_tp_list_find_session(struct batadv_priv *bat_priv, const u8 *dst,
 302                             const u8 *session)
 303 {
 304         struct batadv_tp_vars *pos, *tp_vars = NULL;
 305
 306         rcu_read_lock();
 307         hlist_for_each_entry_rcu(pos, &bat_priv->tp_list, list) {
 308                 if (!batadv_compare_eth(pos->other_end, dst))
 309                         continue;
 310
 311                 if (memcmp(pos->session, session, sizeof(pos->session)) != 0)
 312                         continue;
 313
 314                 /* most of the time this function is invoked during the normal
 315                  * process..it makes sense to pay more when the session is
 316                  * finished and to speed the process up during the measurement
 317                  */
 318                 if (unlikely(!kref_get_unless_zero(&pos->refcount)))
 319                         continue;
 320
 321                 tp_vars = pos;
 322                 break;
 323         }
 324         rcu_read_unlock();
 325
 326         return tp_vars;
 327 }
 328
 329 /**
 330  * batadv_tp_vars_release() - release batadv_tp_vars from lists and queue for
 331  *  free after rcu grace period
 332  * @ref: kref pointer of the batadv_tp_vars
 333  */
 334 static void batadv_tp_vars_release(struct kref *ref)
 335 {
 336         struct batadv_tp_vars *tp_vars;
 337         struct batadv_tp_unacked *un, *safe;
 338
 339         tp_vars = container_of(ref, struct batadv_tp_vars, refcount);
 340
 341         /* lock should not be needed because this object is now out of any
 342          * context!
 343          */
 344         spin_lock_bh(&tp_vars->unacked_lock);
 345         list_for_each_entry_safe(un, safe, &tp_vars->unacked_list, list) {
 346                 list_del(&un->list);
 347                 kfree(un);
 348         }
 349         spin_unlock_bh(&tp_vars->unacked_lock);
 350
 351         kfree_rcu(tp_vars, rcu);
 352 }
 353
 354 /**
 355  * batadv_tp_vars_put() - decrement the batadv_tp_vars refcounter and possibly
 356  *  release it
 357  * @tp_vars: the private data of the current TP meter session to be free'd
 358  */
 359 static void batadv_tp_vars_put(struct batadv_tp_vars *tp_vars)
 360 {
 361         if (!tp_vars)
 362                 return;
 363
 364         kref_put(&tp_vars->refcount, batadv_tp_vars_release);
 365 }
 366
 367 /**
 368  * batadv_tp_sender_cleanup() - cleanup sender data and drop and timer
 369  * @bat_priv: the bat priv with all the soft interface information
 370  * @tp_vars: the private data of the current TP meter session to cleanup
 371  */
 372 static void batadv_tp_sender_cleanup(struct batadv_priv *bat_priv,
 373                                      struct batadv_tp_vars *tp_vars)
 374 {
 375         cancel_delayed_work(&tp_vars->finish_work);
 376
 377         spin_lock_bh(&tp_vars->bat_priv->tp_list_lock);
 378         hlist_del_rcu(&tp_vars->list);
 379         spin_unlock_bh(&tp_vars->bat_priv->tp_list_lock);
 380
 381         /* drop list reference */
 382         batadv_tp_vars_put(tp_vars);
 383
 384         atomic_dec(&tp_vars->bat_priv->tp_num);
 385
 386         /* kill the timer and remove its reference */
 387         del_timer_sync(&tp_vars->timer);
 388         /* the worker might have rearmed itself therefore we kill it again. Note
 389          * that if the worker should run again before invoking the following
 390          * del_timer(), it would not re-arm itself once again because the status
 391          * is OFF now
 392          */
 393         del_timer(&tp_vars->timer);
 394         batadv_tp_vars_put(tp_vars);
 395 }
 396
 397 /**
 398  * batadv_tp_sender_end() - print info about ended session and inform client
 399  * @bat_priv: the bat priv with all the soft interface information
 400  * @tp_vars: the private data of the current TP meter session
 401  */
 402 static void batadv_tp_sender_end(struct batadv_priv *bat_priv,
 403                                  struct batadv_tp_vars *tp_vars)
 404 {
 405         u32 session_cookie;
 406
 407         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 408                    "Test towards %pM finished..shutting down (reason=%d)\n",
 409                    tp_vars->other_end, tp_vars->reason);
 410
 411         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 412                    "Last timing stats: SRTT=%ums RTTVAR=%ums RTO=%ums\n",
 413                    tp_vars->srtt >> 3, tp_vars->rttvar >> 2, tp_vars->rto);
 414
 415         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 416                    "Final values: cwnd=%u ss_threshold=%u\n",
 417                    tp_vars->cwnd, tp_vars->ss_threshold);
 418
 419         session_cookie = batadv_tp_session_cookie(tp_vars->session,
 420                                                   tp_vars->icmp_uid);
 421
 422         batadv_tp_batctl_notify(tp_vars->reason,
 423                                 tp_vars->other_end,
 424                                 bat_priv,
 425                                 tp_vars->start_time,
 426                                 atomic64_read(&tp_vars->tot_sent),
 427                                 session_cookie);
 428 }
 429
 430 /**
 431  * batadv_tp_sender_shutdown() - let sender thread/timer stop gracefully
 432  * @tp_vars: the private data of the current TP meter session
 433  * @reason: reason for tp meter session stop
 434  */
 435 static void batadv_tp_sender_shutdown(struct batadv_tp_vars *tp_vars,
 436                                       enum batadv_tp_meter_reason reason)
 437 {
 438         if (!atomic_dec_and_test(&tp_vars->sending))
 439                 return;
 440
 441         tp_vars->reason = reason;
 442 }
 443
 444 /**
 445  * batadv_tp_sender_finish() - stop sender session after test_length was reached
 446  * @work: delayed work reference of the related tp_vars
 447  */
 448 static void batadv_tp_sender_finish(struct work_struct *work)
 449 {
 450         struct delayed_work *delayed_work;
 451         struct batadv_tp_vars *tp_vars;
 452
 453         delayed_work = to_delayed_work(work);
 454         tp_vars = container_of(delayed_work, struct batadv_tp_vars,
 455                                finish_work);
 456
 457         batadv_tp_sender_shutdown(tp_vars, BATADV_TP_REASON_COMPLETE);
 458 }
 459
 460 /**
 461  * batadv_tp_reset_sender_timer() - reschedule the sender timer
 462  * @tp_vars: the private TP meter data for this session
 463  *
 464  * Reschedule the timer using tp_vars->rto as delay
 465  */
 466 static void batadv_tp_reset_sender_timer(struct batadv_tp_vars *tp_vars)
 467 {
 468         /* most of the time this function is invoked while normal packet
 469          * reception...
 470          */
 471         if (unlikely(atomic_read(&tp_vars->sending) == 0))
 472                 /* timer ref will be dropped in batadv_tp_sender_cleanup */
 473                 return;
 474
 475         mod_timer(&tp_vars->timer, jiffies + msecs_to_jiffies(tp_vars->rto));
 476 }
 477
 478 /**
 479  * batadv_tp_sender_timeout() - timer that fires in case of packet loss
 480  * @t: address to timer_list inside tp_vars
 481  *
 482  * If fired it means that there was packet loss.
 483  * Switch to Slow Start, set the ss_threshold to half of the current cwnd and
 484  * reset the cwnd to 3*MSS
 485  */
 486 static void batadv_tp_sender_timeout(struct timer_list *t)
 487 {
 488         struct batadv_tp_vars *tp_vars = from_timer(tp_vars, t, timer);
 489         struct batadv_priv *bat_priv = tp_vars->bat_priv;
 490
 491         if (atomic_read(&tp_vars->sending) == 0)
 492                 return;
 493
 494         /* if the user waited long enough...shutdown the test */
 495         if (unlikely(tp_vars->rto >= BATADV_TP_MAX_RTO)) {
 496                 batadv_tp_sender_shutdown(tp_vars,
 497                                           BATADV_TP_REASON_DST_UNREACHABLE);
 498                 return;
 499         }
 500
 501         /* RTO exponential backoff
 502          * Details in Section 5.5 of RFC6298
 503          */
 504         tp_vars->rto <<= 1;
 505
 506         spin_lock_bh(&tp_vars->cwnd_lock);
 507
 508         tp_vars->ss_threshold = tp_vars->cwnd >> 1;
 509         if (tp_vars->ss_threshold < BATADV_TP_PLEN * 2)
 510                 tp_vars->ss_threshold = BATADV_TP_PLEN * 2;
 511
 512         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 513                    "Meter: RTO fired during test towards %pM! cwnd=%u new ss_thr=%u, resetting last_sent to %u\n",
 514                    tp_vars->other_end, tp_vars->cwnd, tp_vars->ss_threshold,
 515                    atomic_read(&tp_vars->last_acked));
 516
 517         tp_vars->cwnd = BATADV_TP_PLEN * 3;
 518
 519         spin_unlock_bh(&tp_vars->cwnd_lock);
 520
 521         /* resend the non-ACKed packets.. */
 522         tp_vars->last_sent = atomic_read(&tp_vars->last_acked);
 523         wake_up(&tp_vars->more_bytes);
 524
 525         batadv_tp_reset_sender_timer(tp_vars);
 526 }
 527
 528 /**
 529  * batadv_tp_fill_prerandom() - Fill buffer with prefetched random bytes
 530  * @tp_vars: the private TP meter data for this session
 531  * @buf: Buffer to fill with bytes
 532  * @nbytes: amount of pseudorandom bytes
 533  */
 534 static void batadv_tp_fill_prerandom(struct batadv_tp_vars *tp_vars,
 535                                      u8 *buf, size_t nbytes)
 536 {
 537         u32 local_offset;
 538         size_t bytes_inbuf;
 539         size_t to_copy;
 540         size_t pos = 0;
 541
 542         spin_lock_bh(&tp_vars->prerandom_lock);
 543         local_offset = tp_vars->prerandom_offset;
 544         tp_vars->prerandom_offset += nbytes;
 545         tp_vars->prerandom_offset %= sizeof(batadv_tp_prerandom);
 546         spin_unlock_bh(&tp_vars->prerandom_lock);
 547
 548         while (nbytes) {
 549                 local_offset %= sizeof(batadv_tp_prerandom);
 550                 bytes_inbuf = sizeof(batadv_tp_prerandom) - local_offset;
 551                 to_copy = min(nbytes, bytes_inbuf);
 552
 553                 memcpy(&buf[pos], &batadv_tp_prerandom[local_offset], to_copy);
 554                 pos += to_copy;
 555                 nbytes -= to_copy;
 556                 local_offset = 0;
 557         }
 558 }
 559
 560 /**
 561  * batadv_tp_send_msg() - send a single message
 562  * @tp_vars: the private TP meter data for this session
 563  * @src: source mac address
 564  * @orig_node: the originator of the destination
 565  * @seqno: sequence number of this packet
 566  * @len: length of the entire packet
 567  * @session: session identifier
 568  * @uid: local ICMP "socket" index
 569  * @timestamp: timestamp in jiffies which is replied in ack
 570  *
 571  * Create and send a single TP Meter message.
 572  *
 573  * Return: 0 on success, BATADV_TP_REASON_DST_UNREACHABLE if the destination is
 574  * not reachable, BATADV_TP_REASON_MEMORY_ERROR if the packet couldn't be
 575  * allocated
 576  */
 577 static int batadv_tp_send_msg(struct batadv_tp_vars *tp_vars, const u8 *src,
 578                               struct batadv_orig_node *orig_node,
 579                               u32 seqno, size_t len, const u8 *session,
 580                               int uid, u32 timestamp)
 581 {
 582         struct batadv_icmp_tp_packet *icmp;
 583         struct sk_buff *skb;
 584         int r;
 585         u8 *data;
 586         size_t data_len;
 587
 588         skb = netdev_alloc_skb_ip_align(NULL, len + ETH_HLEN);
 589         if (unlikely(!skb))
 590                 return BATADV_TP_REASON_MEMORY_ERROR;
 591
 592         skb_reserve(skb, ETH_HLEN);
 593         icmp = skb_put(skb, sizeof(*icmp));
 594
 595         /* fill the icmp header */
 596         ether_addr_copy(icmp->dst, orig_node->orig);
 597         ether_addr_copy(icmp->orig, src);
 598         icmp->version = BATADV_COMPAT_VERSION;
 599         icmp->packet_type = BATADV_ICMP;
 600         icmp->ttl = BATADV_TTL;
 601         icmp->msg_type = BATADV_TP;
 602         icmp->uid = uid;
 603
 604         icmp->subtype = BATADV_TP_MSG;
 605         memcpy(icmp->session, session, sizeof(icmp->session));
 606         icmp->seqno = htonl(seqno);
 607         icmp->timestamp = htonl(timestamp);
 608
 609         data_len = len - sizeof(*icmp);
 610         data = skb_put(skb, data_len);
 611         batadv_tp_fill_prerandom(tp_vars, data, data_len);
 612
 613         r = batadv_send_skb_to_orig(skb, orig_node, NULL);
 614         if (r == NET_XMIT_SUCCESS)
 615                 return 0;
 616
 617         return BATADV_TP_REASON_CANT_SEND;
 618 }
 619
 620 /**
 621  * batadv_tp_recv_ack() - ACK receiving function
 622  * @bat_priv: the bat priv with all the soft interface information
 623  * @skb: the buffer containing the received packet
 624  *
 625  * Process a received TP ACK packet
 626  */
 627 static void batadv_tp_recv_ack(struct batadv_priv *bat_priv,
 628                                const struct sk_buff *skb)
 629 {
 630         struct batadv_hard_iface *primary_if = NULL;
 631         struct batadv_orig_node *orig_node = NULL;
 632         const struct batadv_icmp_tp_packet *icmp;
 633         struct batadv_tp_vars *tp_vars;
 634         const unsigned char *dev_addr;
 635         size_t packet_len, mss;
 636         u32 rtt, recv_ack, cwnd;
 637
 638         packet_len = BATADV_TP_PLEN;
 639         mss = BATADV_TP_PLEN;
 640         packet_len += sizeof(struct batadv_unicast_packet);
 641
 642         icmp = (struct batadv_icmp_tp_packet *)skb->data;
 643
 644         /* find the tp_vars */
 645         tp_vars = batadv_tp_list_find_session(bat_priv, icmp->orig,
 646                                               icmp->session);
 647         if (unlikely(!tp_vars))
 648                 return;
 649
 650         if (unlikely(atomic_read(&tp_vars->sending) == 0))
 651                 goto out;
 652
 653         /* old ACK? silently drop it.. */
 654         if (batadv_seq_before(ntohl(icmp->seqno),
 655                               (u32)atomic_read(&tp_vars->last_acked)))
 656                 goto out;
 657
 658         primary_if = batadv_primary_if_get_selected(bat_priv);
 659         if (unlikely(!primary_if))
 660                 goto out;
 661
 662         orig_node = batadv_orig_hash_find(bat_priv, icmp->orig);
 663         if (unlikely(!orig_node))
 664                 goto out;
 665
 666         /* update RTO with the new sampled RTT, if any */
 667         rtt = jiffies_to_msecs(jiffies) - ntohl(icmp->timestamp);
 668         if (icmp->timestamp && rtt)
 669                 batadv_tp_update_rto(tp_vars, rtt);
 670
 671         /* ACK for new data... reset the timer */
 672         batadv_tp_reset_sender_timer(tp_vars);
 673
 674         recv_ack = ntohl(icmp->seqno);
 675
 676         /* check if this ACK is a duplicate */
 677         if (atomic_read(&tp_vars->last_acked) == recv_ack) {
 678                 atomic_inc(&tp_vars->dup_acks);
 679                 if (atomic_read(&tp_vars->dup_acks) != 3)
 680                         goto out;
 681
 682                 if (recv_ack >= tp_vars->recover)
 683                         goto out;
 684
 685                 /* if this is the third duplicate ACK do Fast Retransmit */
 686                 batadv_tp_send_msg(tp_vars, primary_if->net_dev->dev_addr,
 687                                    orig_node, recv_ack, packet_len,
 688                                    icmp->session, icmp->uid,
 689                                    jiffies_to_msecs(jiffies));
 690
 691                 spin_lock_bh(&tp_vars->cwnd_lock);
 692
 693                 /* Fast Recovery */
 694                 tp_vars->fast_recovery = true;
 695                 /* Set recover to the last outstanding seqno when Fast Recovery
 696                  * is entered. RFC6582, Section 3.2, step 1
 697                  */
 698                 tp_vars->recover = tp_vars->last_sent;
 699                 tp_vars->ss_threshold = tp_vars->cwnd >> 1;
 700                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 701                            "Meter: Fast Recovery, (cur cwnd=%u) ss_thr=%u last_sent=%u recv_ack=%u\n",
 702                            tp_vars->cwnd, tp_vars->ss_threshold,
 703                            tp_vars->last_sent, recv_ack);
 704                 tp_vars->cwnd = batadv_tp_cwnd(tp_vars->ss_threshold, 3 * mss,
 705                                                mss);
 706                 tp_vars->dec_cwnd = 0;
 707                 tp_vars->last_sent = recv_ack;
 708
 709                 spin_unlock_bh(&tp_vars->cwnd_lock);
 710         } else {
 711                 /* count the acked data */
 712                 atomic64_add(recv_ack - atomic_read(&tp_vars->last_acked),
 713                              &tp_vars->tot_sent);
 714                 /* reset the duplicate ACKs counter */
 715                 atomic_set(&tp_vars->dup_acks, 0);
 716
 717                 if (tp_vars->fast_recovery) {
 718                         /* partial ACK */
 719                         if (batadv_seq_before(recv_ack, tp_vars->recover)) {
 720                                 /* this is another hole in the window. React
 721                                  * immediately as specified by NewReno (see
 722                                  * Section 3.2 of RFC6582 for details)
 723                                  */
 724                                 dev_addr = primary_if->net_dev->dev_addr;
 725                                 batadv_tp_send_msg(tp_vars, dev_addr,
 726                                                    orig_node, recv_ack,
 727                                                    packet_len, icmp->session,
 728                                                    icmp->uid,
 729                                                    jiffies_to_msecs(jiffies));
 730                                 tp_vars->cwnd = batadv_tp_cwnd(tp_vars->cwnd,
 731                                                                mss, mss);
 732                         } else {
 733                                 tp_vars->fast_recovery = false;
 734                                 /* set cwnd to the value of ss_threshold at the
 735                                  * moment that Fast Recovery was entered.
 736                                  * RFC6582, Section 3.2, step 3
 737                                  */
 738                                 cwnd = batadv_tp_cwnd(tp_vars->ss_threshold, 0,
 739                                                       mss);
 740                                 tp_vars->cwnd = cwnd;
 741                         }
 742                         goto move_twnd;
 743                 }
 744
 745                 if (recv_ack - atomic_read(&tp_vars->last_acked) >= mss)
 746                         batadv_tp_update_cwnd(tp_vars, mss);
 747 move_twnd:
 748                 /* move the Transmit Window */
 749                 atomic_set(&tp_vars->last_acked, recv_ack);
 750         }
 751
 752         wake_up(&tp_vars->more_bytes);
 753 out:
 754         batadv_hardif_put(primary_if);
 755         batadv_orig_node_put(orig_node);
 756         batadv_tp_vars_put(tp_vars);
 757 }
 758
 759 /**
 760  * batadv_tp_avail() - check if congestion window is not full
 761  * @tp_vars: the private data of the current TP meter session
 762  * @payload_len: size of the payload of a single message
 763  *
 764  * Return: true when congestion window is not full, false otherwise
 765  */
 766 static bool batadv_tp_avail(struct batadv_tp_vars *tp_vars,
 767                             size_t payload_len)
 768 {
 769         u32 win_left, win_limit;
 770
 771         win_limit = atomic_read(&tp_vars->last_acked) + tp_vars->cwnd;
 772         win_left = win_limit - tp_vars->last_sent;
 773
 774         return win_left >= payload_len;
 775 }
 776
 777 /**
 778  * batadv_tp_wait_available() - wait until congestion window becomes free or
 779  *  timeout is reached
 780  * @tp_vars: the private data of the current TP meter session
 781  * @plen: size of the payload of a single message
 782  *
 783  * Return: 0 if the condition evaluated to false after the timeout elapsed,
 784  *  1 if the condition evaluated to true after the timeout elapsed, the
 785  *  remaining jiffies (at least 1) if the condition evaluated to true before
 786  *  the timeout elapsed, or -ERESTARTSYS if it was interrupted by a signal.
 787  */
 788 static int batadv_tp_wait_available(struct batadv_tp_vars *tp_vars, size_t plen)
 789 {
 790         int ret;
 791
 792         ret = wait_event_interruptible_timeout(tp_vars->more_bytes,
 793                                                batadv_tp_avail(tp_vars, plen),
 794                                                HZ / 10);
 795
 796         return ret;
 797 }
 798
 799 /**
 800  * batadv_tp_send() - main sending thread of a tp meter session
 801  * @arg: address of the related tp_vars
 802  *
 803  * Return: nothing, this function never returns
 804  */
 805 static int batadv_tp_send(void *arg)
 806 {
 807         struct batadv_tp_vars *tp_vars = arg;
 808         struct batadv_priv *bat_priv = tp_vars->bat_priv;
 809         struct batadv_hard_iface *primary_if = NULL;
 810         struct batadv_orig_node *orig_node = NULL;
 811         size_t payload_len, packet_len;
 812         int err = 0;
 813
 814         if (unlikely(tp_vars->role != BATADV_TP_SENDER)) {
 815                 err = BATADV_TP_REASON_DST_UNREACHABLE;
 816                 tp_vars->reason = err;
 817                 goto out;
 818         }
 819
 820         orig_node = batadv_orig_hash_find(bat_priv, tp_vars->other_end);
 821         if (unlikely(!orig_node)) {
 822                 err = BATADV_TP_REASON_DST_UNREACHABLE;
 823                 tp_vars->reason = err;
 824                 goto out;
 825         }
 826
 827         primary_if = batadv_primary_if_get_selected(bat_priv);
 828         if (unlikely(!primary_if)) {
 829                 err = BATADV_TP_REASON_DST_UNREACHABLE;
 830                 tp_vars->reason = err;
 831                 goto out;
 832         }
 833
 834         /* assume that all the hard_interfaces have a correctly
 835          * configured MTU, so use the soft_iface MTU as MSS.
 836          * This might not be true and in that case the fragmentation
 837          * should be used.
 838          * Now, try to send the packet as it is
 839          */
 840         payload_len = BATADV_TP_PLEN;
 841         BUILD_BUG_ON(sizeof(struct batadv_icmp_tp_packet) > BATADV_TP_PLEN);
 842
 843         batadv_tp_reset_sender_timer(tp_vars);
 844
 845         /* queue the worker in charge of terminating the test */
 846         queue_delayed_work(batadv_event_workqueue, &tp_vars->finish_work,
 847                            msecs_to_jiffies(tp_vars->test_length));
 848
 849         while (atomic_read(&tp_vars->sending) != 0) {
 850                 if (unlikely(!batadv_tp_avail(tp_vars, payload_len))) {
 851                         batadv_tp_wait_available(tp_vars, payload_len);
 852                         continue;
 853                 }
 854
 855                 /* to emulate normal unicast traffic, add to the payload len
 856                  * the size of the unicast header
 857                  */
 858                 packet_len = payload_len + sizeof(struct batadv_unicast_packet);
 859
 860                 err = batadv_tp_send_msg(tp_vars, primary_if->net_dev->dev_addr,
 861                                          orig_node, tp_vars->last_sent,
 862                                          packet_len,
 863                                          tp_vars->session, tp_vars->icmp_uid,
 864                                          jiffies_to_msecs(jiffies));
 865
 866                 /* something went wrong during the preparation/transmission */
 867                 if (unlikely(err && err != BATADV_TP_REASON_CANT_SEND)) {
 868                         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 869                                    "Meter: %s() cannot send packets (%d)\n",
 870                                    __func__, err);
 871                         /* ensure nobody else tries to stop the thread now */
 872                         if (atomic_dec_and_test(&tp_vars->sending))
 873                                 tp_vars->reason = err;
 874                         break;
 875                 }
 876
 877                 /* right-shift the TWND */
 878                 if (!err)
 879                         tp_vars->last_sent += payload_len;
 880
 881                 cond_resched();
 882         }
 883
 884 out:
 885         batadv_hardif_put(primary_if);
 886         batadv_orig_node_put(orig_node);
 887
 888         batadv_tp_sender_end(bat_priv, tp_vars);
 889         batadv_tp_sender_cleanup(bat_priv, tp_vars);
 890
 891         batadv_tp_vars_put(tp_vars);
 892
 893         return 0;
 894 }
 895
 896 /**
 897  * batadv_tp_start_kthread() - start new thread which manages the tp meter
 898  *  sender
 899  * @tp_vars: the private data of the current TP meter session
 900  */
 901 static void batadv_tp_start_kthread(struct batadv_tp_vars *tp_vars)
 902 {
 903         struct task_struct *kthread;
 904         struct batadv_priv *bat_priv = tp_vars->bat_priv;
 905         u32 session_cookie;
 906
 907         kref_get(&tp_vars->refcount);
 908         kthread = kthread_create(batadv_tp_send, tp_vars, "kbatadv_tp_meter");
 909         if (IS_ERR(kthread)) {
 910                 session_cookie = batadv_tp_session_cookie(tp_vars->session,
 911                                                           tp_vars->icmp_uid);
 912                 pr_err("batadv: cannot create tp meter kthread\n");
 913                 batadv_tp_batctl_error_notify(BATADV_TP_REASON_MEMORY_ERROR,
 914                                               tp_vars->other_end,
 915                                               bat_priv, session_cookie);
 916
 917                 /* drop reserved reference for kthread */
 918                 batadv_tp_vars_put(tp_vars);
 919
 920                 /* cleanup of failed tp meter variables */
 921                 batadv_tp_sender_cleanup(bat_priv, tp_vars);
 922                 return;
 923         }
 924
 925         wake_up_process(kthread);
 926 }
 927
 928 /**
 929  * batadv_tp_start() - start a new tp meter session
 930  * @bat_priv: the bat priv with all the soft interface information
 931  * @dst: the receiver MAC address
 932  * @test_length: test length in milliseconds
 933  * @cookie: session cookie
 934  */
 935 void batadv_tp_start(struct batadv_priv *bat_priv, const u8 *dst,
 936                      u32 test_length, u32 *cookie)
 937 {
 938         struct batadv_tp_vars *tp_vars;
 939         u8 session_id[2];
 940         u8 icmp_uid;
 941         u32 session_cookie;
 942
 943         get_random_bytes(session_id, sizeof(session_id));
 944         get_random_bytes(&icmp_uid, 1);
 945         session_cookie = batadv_tp_session_cookie(session_id, icmp_uid);
 946         *cookie = session_cookie;
 947
 948         /* look for an already existing test towards this node */
 949         spin_lock_bh(&bat_priv->tp_list_lock);
 950         tp_vars = batadv_tp_list_find(bat_priv, dst);
 951         if (tp_vars) {
 952                 spin_unlock_bh(&bat_priv->tp_list_lock);
 953                 batadv_tp_vars_put(tp_vars);
 954                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 955                            "Meter: test to or from the same node already ongoing, aborting\n");
 956                 batadv_tp_batctl_error_notify(BATADV_TP_REASON_ALREADY_ONGOING,
 957                                               dst, bat_priv, session_cookie);
 958                 return;
 959         }
 960
 961         if (!atomic_add_unless(&bat_priv->tp_num, 1, BATADV_TP_MAX_NUM)) {
 962                 spin_unlock_bh(&bat_priv->tp_list_lock);
 963                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 964                            "Meter: too many ongoing sessions, aborting (SEND)\n");
 965                 batadv_tp_batctl_error_notify(BATADV_TP_REASON_TOO_MANY, dst,
 966                                               bat_priv, session_cookie);
 967                 return;
 968         }
 969
 970         tp_vars = kmalloc(sizeof(*tp_vars), GFP_ATOMIC);
 971         if (!tp_vars) {
 972                 spin_unlock_bh(&bat_priv->tp_list_lock);
 973                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 974                            "Meter: %s cannot allocate list elements\n",
 975                            __func__);
 976                 batadv_tp_batctl_error_notify(BATADV_TP_REASON_MEMORY_ERROR,
 977                                               dst, bat_priv, session_cookie);
 978                 return;
 979         }
 980
 981         /* initialize tp_vars */
 982         ether_addr_copy(tp_vars->other_end, dst);
 983         kref_init(&tp_vars->refcount);
 984         tp_vars->role = BATADV_TP_SENDER;
 985         atomic_set(&tp_vars->sending, 1);
 986         memcpy(tp_vars->session, session_id, sizeof(session_id));
 987         tp_vars->icmp_uid = icmp_uid;
 988
 989         tp_vars->last_sent = BATADV_TP_FIRST_SEQ;
 990         atomic_set(&tp_vars->last_acked, BATADV_TP_FIRST_SEQ);
 991         tp_vars->fast_recovery = false;
 992         tp_vars->recover = BATADV_TP_FIRST_SEQ;
 993
 994         /* initialise the CWND to 3*MSS (Section 3.1 in RFC5681).
 995          * For batman-adv the MSS is the size of the payload received by the
 996          * soft_interface, hence its MTU
 997          */
 998         tp_vars->cwnd = BATADV_TP_PLEN * 3;
 999         /* at the beginning initialise the SS threshold to the biggest possible
1000          * window size, hence the AWND size
1001          */
1002         tp_vars->ss_threshold = BATADV_TP_AWND;
1003
1004         /* RTO initial value is 3 seconds.
1005          * Details in Section 2.1 of RFC6298
1006          */
1007         tp_vars->rto = 1000;
1008         tp_vars->srtt = 0;
1009         tp_vars->rttvar = 0;
1010
1011         atomic64_set(&tp_vars->tot_sent, 0);
1012
1013         kref_get(&tp_vars->refcount);
1014         timer_setup(&tp_vars->timer, batadv_tp_sender_timeout, 0);
1015
1016         tp_vars->bat_priv = bat_priv;
1017         tp_vars->start_time = jiffies;
1018
1019         init_waitqueue_head(&tp_vars->more_bytes);
1020
1021         spin_lock_init(&tp_vars->unacked_lock);
1022         INIT_LIST_HEAD(&tp_vars->unacked_list);
1023
1024         spin_lock_init(&tp_vars->cwnd_lock);
1025
1026         tp_vars->prerandom_offset = 0;
1027         spin_lock_init(&tp_vars->prerandom_lock);
1028
1029         kref_get(&tp_vars->refcount);
1030         hlist_add_head_rcu(&tp_vars->list, &bat_priv->tp_list);
1031         spin_unlock_bh(&bat_priv->tp_list_lock);
1032
1033         tp_vars->test_length = test_length;
1034         if (!tp_vars->test_length)
1035                 tp_vars->test_length = BATADV_TP_DEF_TEST_LENGTH;
1036
1037         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1038                    "Meter: starting throughput meter towards %pM (length=%ums)\n",
1039                    dst, test_length);
1040
1041         /* init work item for finished tp tests */
1042         INIT_DELAYED_WORK(&tp_vars->finish_work, batadv_tp_sender_finish);
1043
1044         /* start tp kthread. This way the write() call issued from userspace can
1045          * happily return and avoid to block
1046          */
1047         batadv_tp_start_kthread(tp_vars);
1048
1049         /* don't return reference to new tp_vars */
1050         batadv_tp_vars_put(tp_vars);
1051 }
1052
1053 /**
1054  * batadv_tp_stop() - stop currently running tp meter session
1055  * @bat_priv: the bat priv with all the soft interface information
1056  * @dst: the receiver MAC address
1057  * @return_value: reason for tp meter session stop
1058  */
1059 void batadv_tp_stop(struct batadv_priv *bat_priv, const u8 *dst,
1060                     u8 return_value)
1061 {
1062         struct batadv_orig_node *orig_node;
1063         struct batadv_tp_vars *tp_vars;
1064
1065         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1066                    "Meter: stopping test towards %pM\n", dst);
1067
1068         orig_node = batadv_orig_hash_find(bat_priv, dst);
1069         if (!orig_node)
1070                 return;
1071
1072         tp_vars = batadv_tp_list_find(bat_priv, orig_node->orig);
1073         if (!tp_vars) {
1074                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1075                            "Meter: trying to interrupt an already over connection\n");
1076                 goto out;
1077         }
1078
1079         batadv_tp_sender_shutdown(tp_vars, return_value);
1080         batadv_tp_vars_put(tp_vars);
1081 out:
1082         batadv_orig_node_put(orig_node);
1083 }
1084
1085 /**
1086  * batadv_tp_reset_receiver_timer() - reset the receiver shutdown timer
1087  * @tp_vars: the private data of the current TP meter session
1088  *
1089  * start the receiver shutdown timer or reset it if already started
1090  */
1091 static void batadv_tp_reset_receiver_timer(struct batadv_tp_vars *tp_vars)
1092 {
1093         mod_timer(&tp_vars->timer,
1094                   jiffies + msecs_to_jiffies(BATADV_TP_RECV_TIMEOUT));
1095 }
1096
1097 /**
1098  * batadv_tp_receiver_shutdown() - stop a tp meter receiver when timeout is
1099  *  reached without received ack
1100  * @t: address to timer_list inside tp_vars
1101  */
1102 static void batadv_tp_receiver_shutdown(struct timer_list *t)
1103 {
1104         struct batadv_tp_vars *tp_vars = from_timer(tp_vars, t, timer);
1105         struct batadv_tp_unacked *un, *safe;
1106         struct batadv_priv *bat_priv;
1107
1108         bat_priv = tp_vars->bat_priv;
1109
1110         /* if there is recent activity rearm the timer */
1111         if (!batadv_has_timed_out(tp_vars->last_recv_time,
1112                                   BATADV_TP_RECV_TIMEOUT)) {
1113                 /* reset the receiver shutdown timer */
1114                 batadv_tp_reset_receiver_timer(tp_vars);
1115                 return;
1116         }
1117
1118         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1119                    "Shutting down for inactivity (more than %dms) from %pM\n",
1120                    BATADV_TP_RECV_TIMEOUT, tp_vars->other_end);
1121
1122         spin_lock_bh(&tp_vars->bat_priv->tp_list_lock);
1123         hlist_del_rcu(&tp_vars->list);
1124         spin_unlock_bh(&tp_vars->bat_priv->tp_list_lock);
1125
1126         /* drop list reference */
1127         batadv_tp_vars_put(tp_vars);
1128
1129         atomic_dec(&bat_priv->tp_num);
1130
1131         spin_lock_bh(&tp_vars->unacked_lock);
1132         list_for_each_entry_safe(un, safe, &tp_vars->unacked_list, list) {
1133                 list_del(&un->list);
1134                 kfree(un);
1135         }
1136         spin_unlock_bh(&tp_vars->unacked_lock);
1137
1138         /* drop reference of timer */
1139         batadv_tp_vars_put(tp_vars);
1140 }
1141
1142 /**
1143  * batadv_tp_send_ack() - send an ACK packet
1144  * @bat_priv: the bat priv with all the soft interface information
1145  * @dst: the mac address of the destination originator
1146  * @seq: the sequence number to ACK
1147  * @timestamp: the timestamp to echo back in the ACK
1148  * @session: session identifier
1149  * @socket_index: local ICMP socket identifier
1150  *
1151  * Return: 0 on success, a positive integer representing the reason of the
1152  * failure otherwise
1153  */
1154 static int batadv_tp_send_ack(struct batadv_priv *bat_priv, const u8 *dst,
1155                               u32 seq, __be32 timestamp, const u8 *session,
1156                               int socket_index)
1157 {
1158         struct batadv_hard_iface *primary_if = NULL;
1159         struct batadv_orig_node *orig_node;
1160         struct batadv_icmp_tp_packet *icmp;
1161         struct sk_buff *skb;
1162         int r, ret;
1163
1164         orig_node = batadv_orig_hash_find(bat_priv, dst);
1165         if (unlikely(!orig_node)) {
1166                 ret = BATADV_TP_REASON_DST_UNREACHABLE;
1167                 goto out;
1168         }
1169
1170         primary_if = batadv_primary_if_get_selected(bat_priv);
1171         if (unlikely(!primary_if)) {
1172                 ret = BATADV_TP_REASON_DST_UNREACHABLE;
1173                 goto out;
1174         }
1175
1176         skb = netdev_alloc_skb_ip_align(NULL, sizeof(*icmp) + ETH_HLEN);
1177         if (unlikely(!skb)) {
1178                 ret = BATADV_TP_REASON_MEMORY_ERROR;
1179                 goto out;
1180         }
1181
1182         skb_reserve(skb, ETH_HLEN);
1183         icmp = skb_put(skb, sizeof(*icmp));
1184         icmp->packet_type = BATADV_ICMP;
1185         icmp->version = BATADV_COMPAT_VERSION;
1186         icmp->ttl = BATADV_TTL;
1187         icmp->msg_type = BATADV_TP;
1188         ether_addr_copy(icmp->dst, orig_node->orig);
1189         ether_addr_copy(icmp->orig, primary_if->net_dev->dev_addr);
1190         icmp->uid = socket_index;
1191
1192         icmp->subtype = BATADV_TP_ACK;
1193         memcpy(icmp->session, session, sizeof(icmp->session));
1194         icmp->seqno = htonl(seq);
1195         icmp->timestamp = timestamp;
1196
1197         /* send the ack */
1198         r = batadv_send_skb_to_orig(skb, orig_node, NULL);
1199         if (unlikely(r < 0) || r == NET_XMIT_DROP) {
1200                 ret = BATADV_TP_REASON_DST_UNREACHABLE;
1201                 goto out;
1202         }
1203         ret = 0;
1204
1205 out:
1206         batadv_orig_node_put(orig_node);
1207         batadv_hardif_put(primary_if);
1208
1209         return ret;
1210 }
1211
1212 /**
1213  * batadv_tp_handle_out_of_order() - store an out of order packet
1214  * @tp_vars: the private data of the current TP meter session
1215  * @skb: the buffer containing the received packet
1216  *
1217  * Store the out of order packet in the unacked list for late processing. This
1218  * packets are kept in this list so that they can be ACKed at once as soon as
1219  * all the previous packets have been received
1220  *
1221  * Return: true if the packed has been successfully processed, false otherwise
1222  */
1223 static bool batadv_tp_handle_out_of_order(struct batadv_tp_vars *tp_vars,
1224                                           const struct sk_buff *skb)
1225 {
1226         const struct batadv_icmp_tp_packet *icmp;
1227         struct batadv_tp_unacked *un, *new;
1228         u32 payload_len;
1229         bool added = false;
1230
1231         new = kmalloc(sizeof(*new), GFP_ATOMIC);
1232         if (unlikely(!new))
1233                 return false;
1234
1235         icmp = (struct batadv_icmp_tp_packet *)skb->data;
1236
1237         new->seqno = ntohl(icmp->seqno);
1238         payload_len = skb->len - sizeof(struct batadv_unicast_packet);
1239         new->len = payload_len;
1240
1241         spin_lock_bh(&tp_vars->unacked_lock);
1242         /* if the list is empty immediately attach this new object */
1243         if (list_empty(&tp_vars->unacked_list)) {
1244                 list_add(&new->list, &tp_vars->unacked_list);
1245                 goto out;
1246         }
1247
1248         /* otherwise loop over the list and either drop the packet because this
1249          * is a duplicate or store it at the right position.
1250          *
1251          * The iteration is done in the reverse way because it is likely that
1252          * the last received packet (the one being processed now) has a bigger
1253          * seqno than all the others already stored.
1254          */
1255         list_for_each_entry_reverse(un, &tp_vars->unacked_list, list) {
1256                 /* check for duplicates */
1257                 if (new->seqno == un->seqno) {
1258                         if (new->len > un->len)
1259                                 un->len = new->len;
1260                         kfree(new);
1261                         added = true;
1262                         break;
1263                 }
1264
1265                 /* look for the right position */
1266                 if (batadv_seq_before(new->seqno, un->seqno))
1267                         continue;
1268
1269                 /* as soon as an entry having a bigger seqno is found, the new
1270                  * one is attached _after_ it. In this way the list is kept in
1271                  * ascending order
1272                  */
1273                 list_add_tail(&new->list, &un->list);
1274                 added = true;
1275                 break;
1276         }
1277
1278         /* received packet with smallest seqno out of order; add it to front */
1279         if (!added)
1280                 list_add(&new->list, &tp_vars->unacked_list);
1281
1282 out:
1283         spin_unlock_bh(&tp_vars->unacked_lock);
1284
1285         return true;
1286 }
1287
1288 /**
1289  * batadv_tp_ack_unordered() - update number received bytes in current stream
1290  *  without gaps
1291  * @tp_vars: the private data of the current TP meter session
1292  */
1293 static void batadv_tp_ack_unordered(struct batadv_tp_vars *tp_vars)
1294 {
1295         struct batadv_tp_unacked *un, *safe;
1296         u32 to_ack;
1297
1298         /* go through the unacked packet list and possibly ACK them as
1299          * well
1300          */
1301         spin_lock_bh(&tp_vars->unacked_lock);
1302         list_for_each_entry_safe(un, safe, &tp_vars->unacked_list, list) {
1303                 /* the list is ordered, therefore it is possible to stop as soon
1304                  * there is a gap between the last acked seqno and the seqno of
1305                  * the packet under inspection
1306                  */
1307                 if (batadv_seq_before(tp_vars->last_recv, un->seqno))
1308                         break;
1309
1310                 to_ack = un->seqno + un->len - tp_vars->last_recv;
1311
1312                 if (batadv_seq_before(tp_vars->last_recv, un->seqno + un->len))
1313                         tp_vars->last_recv += to_ack;
1314
1315                 list_del(&un->list);
1316                 kfree(un);
1317         }
1318         spin_unlock_bh(&tp_vars->unacked_lock);
1319 }
1320
1321 /**
1322  * batadv_tp_init_recv() - return matching or create new receiver tp_vars
1323  * @bat_priv: the bat priv with all the soft interface information
1324  * @icmp: received icmp tp msg
1325  *
1326  * Return: corresponding tp_vars or NULL on errors
1327  */
1328 static struct batadv_tp_vars *
1329 batadv_tp_init_recv(struct batadv_priv *bat_priv,
1330                     const struct batadv_icmp_tp_packet *icmp)
1331 {
1332         struct batadv_tp_vars *tp_vars;
1333
1334         spin_lock_bh(&bat_priv->tp_list_lock);
1335         tp_vars = batadv_tp_list_find_session(bat_priv, icmp->orig,
1336                                               icmp->session);
1337         if (tp_vars)
1338                 goto out_unlock;
1339
1340         if (!atomic_add_unless(&bat_priv->tp_num, 1, BATADV_TP_MAX_NUM)) {
1341                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1342                            "Meter: too many ongoing sessions, aborting (RECV)\n");
1343                 goto out_unlock;
1344         }
1345
1346         tp_vars = kmalloc(sizeof(*tp_vars), GFP_ATOMIC);
1347         if (!tp_vars)
1348                 goto out_unlock;
1349
1350         ether_addr_copy(tp_vars->other_end, icmp->orig);
1351         tp_vars->role = BATADV_TP_RECEIVER;
1352         memcpy(tp_vars->session, icmp->session, sizeof(tp_vars->session));
1353         tp_vars->last_recv = BATADV_TP_FIRST_SEQ;
1354         tp_vars->bat_priv = bat_priv;
1355         kref_init(&tp_vars->refcount);
1356
1357         spin_lock_init(&tp_vars->unacked_lock);
1358         INIT_LIST_HEAD(&tp_vars->unacked_list);
1359
1360         kref_get(&tp_vars->refcount);
1361         hlist_add_head_rcu(&tp_vars->list, &bat_priv->tp_list);
1362
1363         kref_get(&tp_vars->refcount);
1364         timer_setup(&tp_vars->timer, batadv_tp_receiver_shutdown, 0);
1365
1366         batadv_tp_reset_receiver_timer(tp_vars);
1367
1368 out_unlock:
1369         spin_unlock_bh(&bat_priv->tp_list_lock);
1370
1371         return tp_vars;
1372 }
1373
1374 /**
1375  * batadv_tp_recv_msg() - process a single data message
1376  * @bat_priv: the bat priv with all the soft interface information
1377  * @skb: the buffer containing the received packet
1378  *
1379  * Process a received TP MSG packet
1380  */
1381 static void batadv_tp_recv_msg(struct batadv_priv *bat_priv,
1382                                const struct sk_buff *skb)
1383 {
1384         const struct batadv_icmp_tp_packet *icmp;
1385         struct batadv_tp_vars *tp_vars;
1386         size_t packet_size;
1387         u32 seqno;
1388
1389         icmp = (struct batadv_icmp_tp_packet *)skb->data;
1390
1391         seqno = ntohl(icmp->seqno);
1392         /* check if this is the first seqno. This means that if the
1393          * first packet is lost, the tp meter does not work anymore!
1394          */
1395         if (seqno == BATADV_TP_FIRST_SEQ) {
1396                 tp_vars = batadv_tp_init_recv(bat_priv, icmp);
1397                 if (!tp_vars) {
1398                         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1399                                    "Meter: seqno != BATADV_TP_FIRST_SEQ cannot initiate connection\n");
1400                         goto out;
1401                 }
1402         } else {
1403                 tp_vars = batadv_tp_list_find_session(bat_priv, icmp->orig,
1404                                                       icmp->session);
1405                 if (!tp_vars) {
1406                         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1407                                    "Unexpected packet from %pM!\n",
1408                                    icmp->orig);
1409                         goto out;
1410                 }
1411         }
1412
1413         if (unlikely(tp_vars->role != BATADV_TP_RECEIVER)) {
1414                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1415                            "Meter: dropping packet: not expected (role=%u)\n",
1416                            tp_vars->role);
1417                 goto out;
1418         }
1419
1420         tp_vars->last_recv_time = jiffies;
1421
1422         /* if the packet is a duplicate, it may be the case that an ACK has been
1423          * lost. Resend the ACK
1424          */
1425         if (batadv_seq_before(seqno, tp_vars->last_recv))
1426                 goto send_ack;
1427
1428         /* if the packet is out of order enqueue it */
1429         if (ntohl(icmp->seqno) != tp_vars->last_recv) {
1430                 /* exit immediately (and do not send any ACK) if the packet has
1431                  * not been enqueued correctly
1432                  */
1433                 if (!batadv_tp_handle_out_of_order(tp_vars, skb))
1434                         goto out;
1435
1436                 /* send a duplicate ACK */
1437                 goto send_ack;
1438         }
1439
1440         /* if everything was fine count the ACKed bytes */
1441         packet_size = skb->len - sizeof(struct batadv_unicast_packet);
1442         tp_vars->last_recv += packet_size;
1443
1444         /* check if this ordered message filled a gap.... */
1445         batadv_tp_ack_unordered(tp_vars);
1446
1447 send_ack:
1448         /* send the ACK. If the received packet was out of order, the ACK that
1449          * is going to be sent is a duplicate (the sender will count them and
1450          * possibly enter Fast Retransmit as soon as it has reached 3)
1451          */
1452         batadv_tp_send_ack(bat_priv, icmp->orig, tp_vars->last_recv,
1453                            icmp->timestamp, icmp->session, icmp->uid);
1454 out:
1455         batadv_tp_vars_put(tp_vars);
1456 }
1457
1458 /**
1459  * batadv_tp_meter_recv() - main TP Meter receiving function
1460  * @bat_priv: the bat priv with all the soft interface information
1461  * @skb: the buffer containing the received packet
1462  */
1463 void batadv_tp_meter_recv(struct batadv_priv *bat_priv, struct sk_buff *skb)
1464 {
1465         struct batadv_icmp_tp_packet *icmp;
1466
1467         icmp = (struct batadv_icmp_tp_packet *)skb->data;
1468
1469         switch (icmp->subtype) {
1470         case BATADV_TP_MSG:
1471                 batadv_tp_recv_msg(bat_priv, skb);
1472                 break;
1473         case BATADV_TP_ACK:
1474                 batadv_tp_recv_ack(bat_priv, skb);
1475                 break;
1476         default:
1477                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1478                            "Received unknown TP Metric packet type %u\n",
1479                            icmp->subtype);
1480         }
1481         consume_skb(skb);
1482 }
1483
1484 /**
1485  * batadv_tp_meter_init() - initialize global tp_meter structures
1486  */
1487 void __init batadv_tp_meter_init(void)
1488 {
1489         get_random_bytes(batadv_tp_prerandom, sizeof(batadv_tp_prerandom));
1490 }