policy.c

   1 /*
   2  *   This program is free software; you can redistribute it and/or modify
   3  *   it under the terms of the GNU General Public License as published by
   4  *   the Free Software Foundation; either version 2 of the License.
   5  *
   6  *   This program is distributed in the hope that it will be useful,
   7  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
   8  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   9  *   GNU General Public License for more details.
  10  *
  11  *   You should have received a copy of the GNU General Public License
  12  *   along with this program; if not, write to the Free Software
  13  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
  14  *
  15  *   Copyright (C) 2020 embedd.ch
  16  *   Copyright (C) 2020 Felix Fietkau <nbd@nbd.name>
  17  *   Copyright (C) 2020 John Crispin <john@phrozen.org>
  18  */
  19
  20 #include "usteer.h"
  21 #include "node.h"
  22 #include "event.h"
  23
  24 static bool
  25 below_assoc_threshold(struct sta_info *si_cur, struct sta_info *si_new)
  26 {
  27         int n_assoc_cur = si_cur->node->n_assoc;
  28         int n_assoc_new = si_new->node->n_assoc;
  29         bool ref_5g = si_cur->node->freq > 4000;
  30         bool node_5g = si_new->node->freq > 4000;
  31
  32         if (ref_5g && !node_5g)
  33                 n_assoc_new += config.band_steering_threshold;
  34         else if (!ref_5g && node_5g)
  35                 n_assoc_cur += config.band_steering_threshold;
  36
  37         n_assoc_new += config.load_balancing_threshold;
  38
  39         return n_assoc_new <= n_assoc_cur;
  40 }
  41
  42 static bool
  43 better_signal_strength(struct sta_info *si_cur, struct sta_info *si_new)
  44 {
  45         const bool is_better = si_new->signal - si_cur->signal
  46                                 > (int) config.signal_diff_threshold;
  47
  48         if (!config.signal_diff_threshold)
  49                 return false;
  50
  51         return is_better;
  52 }
  53
  54 static bool
  55 below_load_threshold(struct sta_info *si)
  56 {
  57         return si->node->n_assoc >= config.load_kick_min_clients &&
  58                si->node->load > config.load_kick_threshold;
  59 }
  60
  61 static bool
  62 has_better_load(struct sta_info *si_cur, struct sta_info *si_new)
  63 {
  64         return !below_load_threshold(si_cur) && below_load_threshold(si_new);
  65 }
  66
  67 static bool
  68 below_max_assoc(struct sta_info *si)
  69 {
  70         struct usteer_node *node = si->node;
  71
  72         return !node->max_assoc || node->n_assoc < node->max_assoc;
  73 }
  74
  75 static uint32_t
  76 is_better_candidate(struct sta_info *si_cur, struct sta_info *si_new)
  77 {
  78         uint32_t reasons = 0;
  79
  80         if (!below_max_assoc(si_new))
  81                 return 0;
  82
  83         if (below_assoc_threshold(si_cur, si_new) &&
  84             !below_assoc_threshold(si_new, si_cur))
  85                 reasons |= (1 << UEV_SELECT_REASON_NUM_ASSOC);
  86
  87         if (better_signal_strength(si_cur, si_new))
  88                 reasons |= (1 << UEV_SELECT_REASON_SIGNAL);
  89
  90         if (has_better_load(si_cur, si_new) &&
  91                 !has_better_load(si_cur, si_new))
  92                 reasons |= (1 << UEV_SELECT_REASON_LOAD);
  93
  94         return reasons;
  95 }
  96
  97 static struct sta_info *
  98 find_better_candidate(struct sta_info *si_ref, struct uevent *ev)
  99 {
 100         struct sta_info *si;
 101         struct sta *sta = si_ref->sta;
 102         uint32_t reasons;
 103
 104         list_for_each_entry(si, &sta->nodes, list) {
 105                 if (si == si_ref)
 106                         continue;
 107
 108                 if (current_time - si->seen > config.seen_policy_timeout)
 109                         continue;
 110
 111                 if (strcmp(si->node->ssid, si_ref->node->ssid) != 0)
 112                         continue;
 113
 114                 reasons = is_better_candidate(si_ref, si);
 115                 if (!reasons)
 116                         continue;
 117
 118                 if (is_better_candidate(si, si_ref))
 119                         continue;
 120
 121                 if (ev) {
 122                         ev->si_other = si;
 123                         ev->select_reasons = reasons;
 124                 }
 125
 126                 return si;
 127         }
 128
 129         return NULL;
 130 }
 131
 132 static int
 133 snr_to_signal(struct usteer_node *node, int snr)
 134 {
 135         int noise = -95;
 136
 137         if (snr < 0)
 138                 return snr;
 139
 140         if (node->noise)
 141                 noise = node->noise;
 142
 143         return noise + snr;
 144 }
 145
 146 bool
 147 usteer_check_request(struct sta_info *si, enum usteer_event_type type)
 148 {
 149         struct uevent ev = {
 150                 .si_cur = si,
 151         };
 152         int min_signal;
 153         bool ret = true;
 154
 155         if (type == EVENT_TYPE_AUTH)
 156                 goto out;
 157
 158         if (type == EVENT_TYPE_ASSOC && !config.assoc_steering)
 159                 goto out;
 160
 161         min_signal = snr_to_signal(si->node, config.min_connect_snr);
 162         if (si->signal < min_signal) {
 163                 ev.reason = UEV_REASON_LOW_SIGNAL;
 164                 ev.threshold.cur = si->signal;
 165                 ev.threshold.ref = min_signal;
 166                 ret = false;
 167                 goto out;
 168         }
 169
 170         if (current_time - si->created < config.initial_connect_delay) {
 171                 ev.reason = UEV_REASON_CONNECT_DELAY;
 172                 ev.threshold.cur = current_time - si->created;
 173                 ev.threshold.ref = config.initial_connect_delay;
 174                 ret = false;
 175                 goto out;
 176         }
 177
 178         if (!find_better_candidate(si, &ev))
 179                 goto out;
 180
 181         ev.reason = UEV_REASON_BETTER_CANDIDATE;
 182         ev.node_cur = si->node;
 183         ret = false;
 184
 185 out:
 186         switch (type) {
 187         case EVENT_TYPE_PROBE:
 188                 ev.type = UEV_PROBE_REQ_ACCEPT;
 189                 break;
 190         case EVENT_TYPE_ASSOC:
 191                 ev.type = UEV_ASSOC_REQ_ACCEPT;
 192                 break;
 193         case EVENT_TYPE_AUTH:
 194                 ev.type = UEV_AUTH_REQ_ACCEPT;
 195                 break;
 196         default:
 197                 break;
 198         }
 199
 200         if (!ret)
 201                 ev.type++;
 202
 203         if (!ret && si->stats[type].blocked_cur >= config.max_retry_band) {
 204                 ev.reason = UEV_REASON_RETRY_EXCEEDED;
 205                 ev.threshold.cur = si->stats[type].blocked_cur;
 206                 ev.threshold.ref = config.max_retry_band;
 207         }
 208         usteer_event(&ev);
 209
 210         return ret;
 211 }
 212
 213 static bool
 214 is_more_kickable(struct sta_info *si_cur, struct sta_info *si_new)
 215 {
 216         if (!si_cur)
 217                 return true;
 218
 219         if (si_new->kick_count > si_cur->kick_count)
 220                 return false;
 221
 222         return si_cur->signal > si_new->signal;
 223 }
 224
 225 static void
 226 usteer_roam_set_state(struct sta_info *si, enum roam_trigger_state state,
 227                       struct uevent *ev)
 228 {
 229         si->roam_event = current_time;
 230
 231         if (si->roam_state == state) {
 232                 if (si->roam_state == ROAM_TRIGGER_IDLE) {
 233                         si->roam_tries = 0;
 234                         return;
 235                 }
 236
 237                 si->roam_tries++;
 238         } else {
 239                 si->roam_tries = 0;
 240         }
 241
 242         si->roam_state = state;
 243         usteer_event(ev);
 244 }
 245
 246 static bool
 247 usteer_roam_trigger_sm(struct sta_info *si)
 248 {
 249         struct uevent ev = {
 250                 .si_cur = si,
 251         };
 252         int min_signal;
 253
 254         min_signal = snr_to_signal(si->node, config.roam_trigger_snr);
 255
 256         switch (si->roam_state) {
 257         case ROAM_TRIGGER_SCAN:
 258                 if (current_time - si->roam_event < config.roam_scan_interval)
 259                         break;
 260
 261                 if (find_better_candidate(si, &ev) ||
 262                     si->roam_scan_done > si->roam_event) {
 263                         usteer_roam_set_state(si, ROAM_TRIGGER_SCAN_DONE, &ev);
 264                         break;
 265                 }
 266
 267                 if (config.roam_scan_tries &&
 268                     si->roam_tries >= config.roam_scan_tries) {
 269                         usteer_roam_set_state(si, ROAM_TRIGGER_WAIT_KICK, &ev);
 270                         break;
 271                 }
 272
 273                 usteer_ubus_trigger_client_scan(si);
 274                 usteer_roam_set_state(si, ROAM_TRIGGER_SCAN, &ev);
 275                 break;
 276
 277         case ROAM_TRIGGER_IDLE:
 278                 if (find_better_candidate(si, &ev)) {
 279                         usteer_roam_set_state(si, ROAM_TRIGGER_SCAN_DONE, &ev);
 280                         break;
 281                 }
 282
 283                 usteer_roam_set_state(si, ROAM_TRIGGER_SCAN, &ev);
 284                 break;
 285
 286         case ROAM_TRIGGER_SCAN_DONE:
 287                 /* Check for stale scan results, kick back to SCAN state if necessary */
 288                 if (current_time - si->roam_scan_done > 2 * config.roam_scan_interval) {
 289                         usteer_roam_set_state(si, ROAM_TRIGGER_SCAN, &ev);
 290                         break;
 291                 }
 292
 293                 if (find_better_candidate(si, &ev))
 294                         usteer_roam_set_state(si, ROAM_TRIGGER_WAIT_KICK, &ev);
 295
 296                 break;
 297
 298         case ROAM_TRIGGER_WAIT_KICK:
 299                 if (si->signal > min_signal)
 300                         break;
 301
 302                 usteer_roam_set_state(si, ROAM_TRIGGER_NOTIFY_KICK, &ev);
 303                 usteer_ubus_notify_client_disassoc(si);
 304                 break;
 305         case ROAM_TRIGGER_NOTIFY_KICK:
 306                 if (current_time - si->roam_event < config.roam_kick_delay * 100)
 307                         break;
 308
 309                 usteer_roam_set_state(si, ROAM_TRIGGER_KICK, &ev);
 310                 break;
 311         case ROAM_TRIGGER_KICK:
 312                 usteer_ubus_kick_client(si);
 313                 usteer_roam_set_state(si, ROAM_TRIGGER_IDLE, &ev);
 314                 return true;
 315         }
 316
 317         return false;
 318 }
 319
 320 static void
 321 usteer_local_node_roam_check(struct usteer_local_node *ln, struct uevent *ev)
 322 {
 323         struct sta_info *si;
 324         int min_signal;
 325
 326         if (config.roam_scan_snr)
 327                 min_signal = config.roam_scan_snr;
 328         else if (config.roam_trigger_snr)
 329                 min_signal = config.roam_trigger_snr;
 330         else
 331                 return;
 332
 333         usteer_update_time();
 334         min_signal = snr_to_signal(&ln->node, min_signal);
 335
 336         list_for_each_entry(si, &ln->node.sta_info, node_list) {
 337                 if (!si->connected || si->signal >= min_signal ||
 338                     current_time - si->roam_kick < config.roam_trigger_interval) {
 339                         usteer_roam_set_state(si, ROAM_TRIGGER_IDLE, ev);
 340                         continue;
 341                 }
 342
 343                 /*
 344                  * If the state machine kicked a client, other clients should wait
 345                  * until the next turn
 346                  */
 347                 if (usteer_roam_trigger_sm(si))
 348                         return;
 349         }
 350 }
 351
 352 static void
 353 usteer_local_node_snr_kick(struct usteer_local_node *ln)
 354 {
 355         struct uevent ev = {
 356                 .node_local = &ln->node,
 357         };
 358         struct sta_info *si;
 359         int min_signal;
 360
 361         if (!config.min_snr)
 362                 return;
 363
 364         min_signal = snr_to_signal(&ln->node, config.min_snr);
 365         ev.threshold.ref = min_signal;
 366
 367         list_for_each_entry(si, &ln->node.sta_info, node_list) {
 368                 if (!si->connected)
 369                         continue;
 370
 371                 if (si->signal >= min_signal)
 372                         continue;
 373
 374                 si->kick_count++;
 375
 376                 ev.type = UEV_SIGNAL_KICK;
 377                 ev.threshold.cur = si->signal;
 378                 ev.count = si->kick_count;
 379                 usteer_event(&ev);
 380
 381                 usteer_ubus_kick_client(si);
 382                 return;
 383         }
 384 }
 385
 386 void
 387 usteer_local_node_kick(struct usteer_local_node *ln)
 388 {
 389         struct usteer_node *node = &ln->node;
 390         struct sta_info *kick1 = NULL, *kick2 = NULL;
 391         struct sta_info *candidate = NULL;
 392         struct sta_info *si;
 393         struct uevent ev = {
 394                 .node_local = &ln->node,
 395         };
 396         unsigned int min_count = DIV_ROUND_UP(config.load_kick_delay, config.local_sta_update);
 397
 398         usteer_local_node_roam_check(ln, &ev);
 399         usteer_local_node_snr_kick(ln);
 400
 401         if (!config.load_kick_enabled || !config.load_kick_threshold ||
 402             !config.load_kick_delay)
 403                 return;
 404
 405         if (node->load < config.load_kick_threshold) {
 406                 if (!ln->load_thr_count)
 407                         return;
 408
 409                 ln->load_thr_count = 0;
 410                 ev.type = UEV_LOAD_KICK_RESET;
 411                 ev.threshold.cur = node->load;
 412                 ev.threshold.ref = config.load_kick_threshold;
 413                 goto out;
 414         }
 415
 416         if (++ln->load_thr_count <= min_count) {
 417                 if (ln->load_thr_count > 1)
 418                         return;
 419
 420                 ev.type = UEV_LOAD_KICK_TRIGGER;
 421                 ev.threshold.cur = node->load;
 422                 ev.threshold.ref = config.load_kick_threshold;
 423                 goto out;
 424         }
 425
 426         ln->load_thr_count = 0;
 427         if (node->n_assoc < config.load_kick_min_clients) {
 428                 ev.type = UEV_LOAD_KICK_MIN_CLIENTS;
 429                 ev.threshold.cur = node->n_assoc;
 430                 ev.threshold.ref = config.load_kick_min_clients;
 431                 goto out;
 432         }
 433
 434         list_for_each_entry(si, &ln->node.sta_info, node_list) {
 435                 struct sta_info *tmp;
 436
 437                 if (!si->connected)
 438                         continue;
 439
 440                 if (is_more_kickable(kick1, si))
 441                         kick1 = si;
 442
 443                 tmp = find_better_candidate(si, NULL);
 444                 if (!tmp)
 445                         continue;
 446
 447                 if (is_more_kickable(kick2, si)) {
 448                         kick2 = si;
 449                         candidate = tmp;
 450                 }
 451         }
 452
 453         if (!kick1) {
 454                 ev.type = UEV_LOAD_KICK_NO_CLIENT;
 455                 goto out;
 456         }
 457
 458         if (kick2)
 459                 kick1 = kick2;
 460
 461         kick1->kick_count++;
 462
 463         ev.type = UEV_LOAD_KICK_CLIENT;
 464         ev.si_cur = kick1;
 465         ev.si_other = candidate;
 466         ev.count = kick1->kick_count;
 467
 468         usteer_ubus_kick_client(kick1);
 469
 470 out:
 471         usteer_event(&ev);
 472 }