src/neighbors.cc

   1 /*
   2  * Copyright (C) 1996-2018 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 /* DEBUG: section 15    Neighbor Routines */
  10
  11 #include "squid.h"
  12 #include "acl/FilledChecklist.h"
  13 #include "anyp/PortCfg.h"
  14 #include "base/EnumIterator.h"
  15 #include "CacheDigest.h"
  16 #include "CachePeer.h"
  17 #include "comm/Connection.h"
  18 #include "comm/ConnOpener.h"
  19 #include "event.h"
  20 #include "FwdState.h"
  21 #include "globals.h"
  22 #include "htcp.h"
  23 #include "HttpRequest.h"
  24 #include "icmp/net_db.h"
  25 #include "ICP.h"
  26 #include "int.h"
  27 #include "ip/Address.h"
  28 #include "ip/tools.h"
  29 #include "ipcache.h"
  30 #include "MemObject.h"
  31 #include "mgr/Registration.h"
  32 #include "multicast.h"
  33 #include "neighbors.h"
  34 #include "NeighborTypeDomainList.h"
  35 #include "pconn.h"
  36 #include "PeerDigest.h"
  37 #include "PeerPoolMgr.h"
  38 #include "PeerSelectState.h"
  39 #include "RequestFlags.h"
  40 #include "SquidConfig.h"
  41 #include "SquidMath.h"
  42 #include "SquidTime.h"
  43 #include "stat.h"
  44 #include "Store.h"
  45 #include "store_key_md5.h"
  46 #include "tools.h"
  47 #include "URL.h"
  48
  49 /* count mcast group peers every 15 minutes */
  50 #define MCAST_COUNT_RATE 900
  51
  52 bool peerAllowedToUse(const CachePeer *, HttpRequest *);
  53 static int peerWouldBePinged(const CachePeer *, HttpRequest *);
  54 static void neighborRemove(CachePeer *);
  55 static void neighborAlive(CachePeer *, const MemObject *, const icp_common_t *);
  56 #if USE_HTCP
  57 static void neighborAliveHtcp(CachePeer *, const MemObject *, const HtcpReplyData *);
  58 #endif
  59 static void neighborCountIgnored(CachePeer *);
  60 static void peerRefreshDNS(void *);
  61 static IPH peerDNSConfigure;
  62 static void peerProbeConnect(CachePeer *, const bool reprobeIfBusy = false);
  63 static CNCB peerProbeConnectDone;
  64 static void peerCountMcastPeersDone(void *data);
  65 static void peerCountMcastPeersStart(void *data);
  66 static void peerCountMcastPeersSchedule(CachePeer * p, time_t when);
  67 static IRCB peerCountHandleIcpReply;
  68
  69 static void neighborIgnoreNonPeer(const Ip::Address &, icp_opcode);
  70 static OBJH neighborDumpPeers;
  71 static OBJH neighborDumpNonPeers;
  72 static void dump_peers(StoreEntry * sentry, CachePeer * peers);
  73
  74 static unsigned short echo_port;
  75
  76 static int NLateReplies = 0;
  77 static CachePeer *first_ping = NULL;
  78
  79 const char *
  80 neighborTypeStr(const CachePeer * p)
  81 {
  82     if (p->type == PEER_NONE)
  83         return "Non-Peer";
  84
  85     if (p->type == PEER_SIBLING)
  86         return "Sibling";
  87
  88     if (p->type == PEER_MULTICAST)
  89         return "Multicast Group";
  90
  91     return "Parent";
  92 }
  93
  94 CachePeer *
  95 whichPeer(const Ip::Address &from)
  96 {
  97     int j;
  98
  99     CachePeer *p = NULL;
 100     debugs(15, 3, "whichPeer: from " << from);
 101
 102     for (p = Config.peers; p; p = p->next) {
 103         for (j = 0; j < p->n_addresses; ++j) {
 104             if (from == p->addresses[j] && from.port() == p->icp.port) {
 105                 return p;
 106             }
 107         }
 108     }
 109
 110     return NULL;
 111 }
 112
 113 peer_t
 114 neighborType(const CachePeer * p, const URL &url)
 115 {
 116
 117     const NeighborTypeDomainList *d = NULL;
 118
 119     for (d = p->typelist; d; d = d->next) {
 120         if (0 == matchDomainName(url.host(), d->domain))
 121             if (d->type != PEER_NONE)
 122                 return d->type;
 123     }
 124 #if PEER_MULTICAST_SIBLINGS
 125     if (p->type == PEER_MULTICAST)
 126         if (p->options.mcast_siblings)
 127             return PEER_SIBLING;
 128 #endif
 129
 130     return p->type;
 131 }
 132
 133 /**
 134  * \return Whether it is appropriate to fetch REQUEST from PEER.
 135  */
 136 bool
 137 peerAllowedToUse(const CachePeer * p, HttpRequest * request)
 138 {
 139
 140     assert(request != NULL);
 141
 142     if (neighborType(p, request->url) == PEER_SIBLING) {
 143 #if PEER_MULTICAST_SIBLINGS
 144         if (p->type == PEER_MULTICAST && p->options.mcast_siblings &&
 145                 (request->flags.noCache || request->flags.refresh || request->flags.loopDetected || request->flags.needValidation))
 146             debugs(15, 2, "peerAllowedToUse(" << p->name << ", " << request->url.authority() << ") : multicast-siblings optimization match");
 147 #endif
 148         if (request->flags.noCache)
 149             return false;
 150
 151         if (request->flags.refresh)
 152             return false;
 153
 154         if (request->flags.loopDetected)
 155             return false;
 156
 157         if (request->flags.needValidation)
 158             return false;
 159     }
 160
 161     // CONNECT requests are proxy requests. Not to be forwarded to origin servers.
 162     // Unless the destination port matches, in which case we MAY perform a 'DIRECT' to this CachePeer.
 163     if (p->options.originserver && request->method == Http::METHOD_CONNECT && request->url.port() != p->http_port)
 164         return false;
 165
 166     if (p->access == NULL)
 167         return true;
 168
 169     ACLFilledChecklist checklist(p->access, request, NULL);
 170
 171     return checklist.fastCheck().allowed();
 172 }
 173
 174 /* Return TRUE if it is okay to send an ICP request to this CachePeer.   */
 175 static int
 176 peerWouldBePinged(const CachePeer * p, HttpRequest * request)
 177 {
 178     if (p->icp.port == 0)
 179         return 0;
 180
 181     if (p->options.no_query)
 182         return 0;
 183
 184     if (p->options.mcast_responder)
 185         return 0;
 186
 187     if (p->n_addresses == 0)
 188         return 0;
 189
 190     if (p->options.background_ping && (squid_curtime - p->stats.last_query < Config.backgroundPingRate))
 191         return 0;
 192
 193     /* the case below seems strange, but can happen if the
 194      * URL host is on the other side of a firewall */
 195     if (p->type == PEER_SIBLING)
 196         if (!request->flags.hierarchical)
 197             return 0;
 198
 199     if (!peerAllowedToUse(p, request))
 200         return 0;
 201
 202     /* Ping dead peers every timeout interval */
 203     if (squid_curtime - p->stats.last_query > Config.Timeout.deadPeer)
 204         return 1;
 205
 206     if (!neighborUp(p))
 207         return 0;
 208
 209     return 1;
 210 }
 211
 212 bool
 213 peerCanOpenMore(const CachePeer *p)
 214 {
 215     const int effectiveLimit = p->max_conn <= 0 ? Squid_MaxFD : p->max_conn;
 216     const int remaining = effectiveLimit - p->stats.conn_open;
 217     debugs(15, 7, remaining << '=' << effectiveLimit << '-' << p->stats.conn_open);
 218     return remaining > 0;
 219 }
 220
 221 bool
 222 peerHasConnAvailable(const CachePeer *p)
 223 {
 224     // Standby connections can be used without opening new connections.
 225     const int standbys = p->standby.pool ? p->standby.pool->count() : 0;
 226
 227     // XXX: Some idle pconns can be used without opening new connections.
 228     // Complication: Idle pconns cannot be reused for some requests.
 229     const int usableIdles = 0;
 230
 231     const int available = standbys + usableIdles;
 232     debugs(15, 7, available << '=' << standbys << '+' << usableIdles);
 233     return available > 0;
 234 }
 235
 236 void
 237 peerConnClosed(CachePeer *p)
 238 {
 239     --p->stats.conn_open;
 240     if (p->standby.waitingForClose && peerCanOpenMore(p)) {
 241         p->standby.waitingForClose = false;
 242         PeerPoolMgr::Checkpoint(p->standby.mgr, "conn closed");
 243     }
 244 }
 245
 246 /* Return TRUE if it is okay to send an HTTP request to this CachePeer. */
 247 int
 248 peerHTTPOkay(const CachePeer * p, HttpRequest * request)
 249 {
 250     if (!peerCanOpenMore(p) && !peerHasConnAvailable(p))
 251         return 0;
 252
 253     if (!peerAllowedToUse(p, request))
 254         return 0;
 255
 256     if (!neighborUp(p))
 257         return 0;
 258
 259     return 1;
 260 }
 261
 262 int
 263 neighborsCount(HttpRequest * request)
 264 {
 265     CachePeer *p = NULL;
 266     int count = 0;
 267
 268     for (p = Config.peers; p; p = p->next)
 269         if (peerWouldBePinged(p, request))
 270             ++count;
 271
 272     debugs(15, 3, "neighborsCount: " << count);
 273
 274     return count;
 275 }
 276
 277 CachePeer *
 278 getFirstUpParent(HttpRequest * request)
 279 {
 280     CachePeer *p = NULL;
 281
 282     for (p = Config.peers; p; p = p->next) {
 283         if (!neighborUp(p))
 284             continue;
 285
 286         if (neighborType(p, request->url) != PEER_PARENT)
 287             continue;
 288
 289         if (!peerHTTPOkay(p, request))
 290             continue;
 291
 292         break;
 293     }
 294
 295     debugs(15, 3, "getFirstUpParent: returning " << (p ? p->host : "NULL"));
 296     return p;
 297 }
 298
 299 CachePeer *
 300 getRoundRobinParent(HttpRequest * request)
 301 {
 302     CachePeer *p;
 303     CachePeer *q = NULL;
 304
 305     for (p = Config.peers; p; p = p->next) {
 306         if (!p->options.roundrobin)
 307             continue;
 308
 309         if (neighborType(p, request->url) != PEER_PARENT)
 310             continue;
 311
 312         if (!peerHTTPOkay(p, request))
 313             continue;
 314
 315         if (p->weight == 0)
 316             continue;
 317
 318         if (q) {
 319             if (p->weight == q->weight) {
 320                 if (q->rr_count < p->rr_count)
 321                     continue;
 322             } else if ( ((double) q->rr_count / q->weight) < ((double) p->rr_count / p->weight)) {
 323                 continue;
 324             }
 325         }
 326
 327         q = p;
 328     }
 329
 330     if (q)
 331         ++ q->rr_count;
 332
 333     debugs(15, 3, HERE << "returning " << (q ? q->host : "NULL"));
 334
 335     return q;
 336 }
 337
 338 CachePeer *
 339 getWeightedRoundRobinParent(HttpRequest * request)
 340 {
 341     CachePeer *p;
 342     CachePeer *q = NULL;
 343     int weighted_rtt;
 344
 345     for (p = Config.peers; p; p = p->next) {
 346         if (!p->options.weighted_roundrobin)
 347             continue;
 348
 349         if (neighborType(p, request->url) != PEER_PARENT)
 350             continue;
 351
 352         if (!peerHTTPOkay(p, request))
 353             continue;
 354
 355         if (q && q->rr_count < p->rr_count)
 356             continue;
 357
 358         q = p;
 359     }
 360
 361     if (q && q->rr_count > 1000000)
 362         for (p = Config.peers; p; p = p->next) {
 363             if (!p->options.weighted_roundrobin)
 364                 continue;
 365
 366             if (neighborType(p, request->url) != PEER_PARENT)
 367                 continue;
 368
 369             p->rr_count = 0;
 370         }
 371
 372     if (q) {
 373         weighted_rtt = (q->stats.rtt - q->basetime) / q->weight;
 374
 375         if (weighted_rtt < 1)
 376             weighted_rtt = 1;
 377
 378         q->rr_count += weighted_rtt;
 379
 380         debugs(15, 3, "getWeightedRoundRobinParent: weighted_rtt " << weighted_rtt);
 381     }
 382
 383     debugs(15, 3, "getWeightedRoundRobinParent: returning " << (q ? q->host : "NULL"));
 384     return q;
 385 }
 386
 387 /**
 388  * This gets called every 5 minutes to clear the round-robin counter.
 389  * The exact timing is an arbitrary default, set on estimate timing of a
 390  * large number of requests in a high-performance environment during the
 391  * period. The larger the number of requests between cycled resets the
 392  * more balanced the operations.
 393  *
 394  \param data    unused.
 395  \todo Make the reset timing a selectable parameter in squid.conf
 396  */
 397 static void
 398 peerClearRRLoop(void *data)
 399 {
 400     peerClearRR();
 401     eventAdd("peerClearRR", peerClearRRLoop, data, 5 * 60.0, 0);
 402 }
 403
 404 /**
 405  * This gets called on startup and restart to kick off the CachePeer round-robin
 406  * maintenance event. It ensures that no matter how many times its called
 407  * no more than one event is scheduled.
 408  */
 409 void
 410 peerClearRRStart(void)
 411 {
 412     static bool event_added = false;
 413     if (!event_added) {
 414         peerClearRRLoop(NULL);
 415         event_added=true;
 416     }
 417 }
 418
 419 /**
 420  * Called whenever the round-robin counters need to be reset to a sane state.
 421  * So far those times are:
 422  *  - On startup and reconfigure - to set the counters to sane initial settings.
 423  *  -  When a CachePeer has revived from dead, to prevent the revived CachePeer being
 424  *     flooded with requests which it has 'missed' during the down period.
 425  */
 426 void
 427 peerClearRR()
 428 {
 429     CachePeer *p = NULL;
 430     for (p = Config.peers; p; p = p->next) {
 431         p->rr_count = 1;
 432     }
 433 }
 434
 435 /**
 436  * Perform all actions when a CachePeer is detected revived.
 437  */
 438 void
 439 peerAlive(CachePeer *p)
 440 {
 441     if (p->stats.logged_state == PEER_DEAD && p->tcp_up) {
 442         debugs(15, DBG_IMPORTANT, "Detected REVIVED " << neighborTypeStr(p) << ": " << p->name);
 443         p->stats.logged_state = PEER_ALIVE;
 444         peerClearRR();
 445         if (p->standby.mgr.valid())
 446             PeerPoolMgr::Checkpoint(p->standby.mgr, "revived peer");
 447     }
 448
 449     p->stats.last_reply = squid_curtime;
 450     p->stats.probe_start = 0;
 451 }
 452
 453 CachePeer *
 454 getDefaultParent(HttpRequest * request)
 455 {
 456     CachePeer *p = NULL;
 457
 458     for (p = Config.peers; p; p = p->next) {
 459         if (neighborType(p, request->url) != PEER_PARENT)
 460             continue;
 461
 462         if (!p->options.default_parent)
 463             continue;
 464
 465         if (!peerHTTPOkay(p, request))
 466             continue;
 467
 468         debugs(15, 3, "getDefaultParent: returning " << p->host);
 469
 470         return p;
 471     }
 472
 473     debugs(15, 3, "getDefaultParent: returning NULL");
 474     return NULL;
 475 }
 476
 477 CachePeer *
 478 getNextPeer(CachePeer * p)
 479 {
 480     return p->next;
 481 }
 482
 483 CachePeer *
 484 getFirstPeer(void)
 485 {
 486     return Config.peers;
 487 }
 488
 489 static void
 490 neighborRemove(CachePeer * target)
 491 {
 492     CachePeer *p = NULL;
 493     CachePeer **P = NULL;
 494     p = Config.peers;
 495     P = &Config.peers;
 496
 497     while (p) {
 498         if (target == p)
 499             break;
 500
 501         P = &p->next;
 502
 503         p = p->next;
 504     }
 505
 506     if (p) {
 507         *P = p->next;
 508         p->next = NULL;
 509         delete p;
 510         --Config.npeers;
 511     }
 512
 513     first_ping = Config.peers;
 514 }
 515
 516 static void
 517 neighborsRegisterWithCacheManager()
 518 {
 519     Mgr::RegisterAction("server_list",
 520                         "Peer Cache Statistics",
 521                         neighborDumpPeers, 0, 1);
 522
 523     if (Comm::IsConnOpen(icpIncomingConn)) {
 524         Mgr::RegisterAction("non_peers",
 525                             "List of Unknown sites sending ICP messages",
 526                             neighborDumpNonPeers, 0, 1);
 527     }
 528 }
 529
 530 void
 531 neighbors_init(void)
 532 {
 533     struct servent *sep = NULL;
 534     const char *me = getMyHostname();
 535     CachePeer *thisPeer = NULL;
 536     CachePeer *next = NULL;
 537
 538     neighborsRegisterWithCacheManager();
 539
 540     if (Comm::IsConnOpen(icpIncomingConn)) {
 541
 542         for (thisPeer = Config.peers; thisPeer; thisPeer = next) {
 543             next = thisPeer->next;
 544
 545             if (0 != strcmp(thisPeer->host, me))
 546                 continue;
 547
 548             for (AnyP::PortCfgPointer s = HttpPortList; s != NULL; s = s->next) {
 549                 if (thisPeer->http_port != s->s.port())
 550                     continue;
 551
 552                 debugs(15, DBG_IMPORTANT, "WARNING: Peer looks like this host");
 553
 554                 debugs(15, DBG_IMPORTANT, "         Ignoring " <<
 555                        neighborTypeStr(thisPeer) << " " << thisPeer->host <<
 556                        "/" << thisPeer->http_port << "/" <<
 557                        thisPeer->icp.port);
 558
 559                 neighborRemove(thisPeer);
 560             }
 561         }
 562     }
 563
 564     peerRefreshDNS((void *) 1);
 565
 566     sep = getservbyname("echo", "udp");
 567     echo_port = sep ? ntohs((unsigned short) sep->s_port) : 7;
 568
 569     first_ping = Config.peers;
 570 }
 571
 572 int
 573 neighborsUdpPing(HttpRequest * request,
 574                  StoreEntry * entry,
 575                  IRCB * callback,
 576                  void *callback_data,
 577                  int *exprep,
 578                  int *timeout)
 579 {
 580     const char *url = entry->url();
 581     MemObject *mem = entry->mem_obj;
 582     CachePeer *p = NULL;
 583     int i;
 584     int reqnum = 0;
 585     int flags;
 586     icp_common_t *query;
 587     int queries_sent = 0;
 588     int peers_pinged = 0;
 589     int parent_timeout = 0, parent_exprep = 0;
 590     int sibling_timeout = 0, sibling_exprep = 0;
 591     int mcast_timeout = 0, mcast_exprep = 0;
 592
 593     if (Config.peers == NULL)
 594         return 0;
 595
 596     assert(entry->swap_status == SWAPOUT_NONE);
 597
 598     mem->start_ping = current_time;
 599
 600     mem->ping_reply_callback = callback;
 601
 602     mem->ircb_data = callback_data;
 603
 604     reqnum = icpSetCacheKey((const cache_key *)entry->key);
 605
 606     for (i = 0, p = first_ping; i++ < Config.npeers; p = p->next) {
 607         if (p == NULL)
 608             p = Config.peers;
 609
 610         debugs(15, 5, "neighborsUdpPing: Peer " << p->host);
 611
 612         if (!peerWouldBePinged(p, request))
 613             continue;       /* next CachePeer */
 614
 615         ++peers_pinged;
 616
 617         debugs(15, 4, "neighborsUdpPing: pinging peer " << p->host << " for '" << url << "'");
 618
 619         debugs(15, 3, "neighborsUdpPing: key = '" << entry->getMD5Text() << "'");
 620
 621         debugs(15, 3, "neighborsUdpPing: reqnum = " << reqnum);
 622
 623 #if USE_HTCP
 624         if (p->options.htcp && !p->options.htcp_only_clr) {
 625             if (Config.Port.htcp <= 0) {
 626                 debugs(15, DBG_CRITICAL, "HTCP is disabled! Cannot send HTCP request to peer.");
 627                 continue;
 628             }
 629
 630             debugs(15, 3, "neighborsUdpPing: sending HTCP query");
 631             if (htcpQuery(entry, request, p) <= 0)
 632                 continue; // unable to send.
 633         } else
 634 #endif
 635         {
 636             if (Config.Port.icp <= 0 || !Comm::IsConnOpen(icpOutgoingConn)) {
 637                 debugs(15, DBG_CRITICAL, "ICP is disabled! Cannot send ICP request to peer.");
 638                 continue;
 639             } else {
 640
 641                 if (p->type == PEER_MULTICAST)
 642                     mcastSetTtl(icpOutgoingConn->fd, p->mcast.ttl);
 643
 644                 if (p->icp.port == echo_port) {
 645                     debugs(15, 4, "neighborsUdpPing: Looks like a dumb cache, send DECHO ping");
 646                     query = icp_common_t::CreateMessage(ICP_DECHO, 0, url, reqnum, 0);
 647                     icpUdpSend(icpOutgoingConn->fd, p->in_addr, query, LOG_ICP_QUERY, 0);
 648                 } else {
 649                     flags = 0;
 650
 651                     if (Config.onoff.query_icmp)
 652                         if (p->icp.version == ICP_VERSION_2)
 653                             flags |= ICP_FLAG_SRC_RTT;
 654
 655                     query = icp_common_t::CreateMessage(ICP_QUERY, flags, url, reqnum, 0);
 656
 657                     icpUdpSend(icpOutgoingConn->fd, p->in_addr, query, LOG_ICP_QUERY, 0.0);
 658                 }
 659             }
 660         }
 661
 662         ++queries_sent;
 663
 664         ++ p->stats.pings_sent;
 665
 666         if (p->type == PEER_MULTICAST) {
 667             mcast_exprep += p->mcast.n_replies_expected;
 668             mcast_timeout += (p->stats.rtt * p->mcast.n_replies_expected);
 669         } else if (neighborUp(p)) {
 670             /* its alive, expect a reply from it */
 671
 672             if (neighborType(p, request->url) == PEER_PARENT) {
 673                 ++parent_exprep;
 674                 parent_timeout += p->stats.rtt;
 675             } else {
 676                 ++sibling_exprep;
 677                 sibling_timeout += p->stats.rtt;
 678             }
 679         } else {
 680             /* Neighbor is dead; ping it anyway, but don't expect a reply */
 681             /* log it once at the threshold */
 682
 683             if (p->stats.logged_state == PEER_ALIVE) {
 684                 debugs(15, DBG_IMPORTANT, "Detected DEAD " << neighborTypeStr(p) << ": " << p->name);
 685                 p->stats.logged_state = PEER_DEAD;
 686             }
 687         }
 688
 689         p->stats.last_query = squid_curtime;
 690
 691         /*
 692          * keep probe_start == 0 for a multicast CachePeer,
 693          * so neighborUp() never says this CachePeer is dead.
 694          */
 695
 696         if ((p->type != PEER_MULTICAST) && (p->stats.probe_start == 0))
 697             p->stats.probe_start = squid_curtime;
 698     }
 699
 700     if ((first_ping = first_ping->next) == NULL)
 701         first_ping = Config.peers;
 702
 703     /*
 704      * How many replies to expect?
 705      */
 706     *exprep = parent_exprep + sibling_exprep + mcast_exprep;
 707
 708     /*
 709      * If there is a configured timeout, use it
 710      */
 711     if (Config.Timeout.icp_query)
 712         *timeout = Config.Timeout.icp_query;
 713     else {
 714         if (*exprep > 0) {
 715             if (parent_exprep)
 716                 *timeout = 2 * parent_timeout / parent_exprep;
 717             else if (mcast_exprep)
 718                 *timeout = 2 * mcast_timeout / mcast_exprep;
 719             else
 720                 *timeout = 2 * sibling_timeout / sibling_exprep;
 721         } else
 722             *timeout = 2000;    /* 2 seconds */
 723
 724         if (Config.Timeout.icp_query_max)
 725             if (*timeout > Config.Timeout.icp_query_max)
 726                 *timeout = Config.Timeout.icp_query_max;
 727
 728         if (*timeout < Config.Timeout.icp_query_min)
 729             *timeout = Config.Timeout.icp_query_min;
 730     }
 731
 732     return peers_pinged;
 733 }
 734
 735 /* lookup the digest of a given CachePeer */
 736 lookup_t
 737 peerDigestLookup(CachePeer * p, HttpRequest * request)
 738 {
 739 #if USE_CACHE_DIGESTS
 740     const cache_key *key = request ? storeKeyPublicByRequest(request) : NULL;
 741     assert(p);
 742     assert(request);
 743     debugs(15, 5, "peerDigestLookup: peer " << p->host);
 744     /* does the peeer have a valid digest? */
 745
 746     if (!p->digest) {
 747         debugs(15, 5, "peerDigestLookup: gone!");
 748         return LOOKUP_NONE;
 749     } else if (!peerHTTPOkay(p, request)) {
 750         debugs(15, 5, "peerDigestLookup: !peerHTTPOkay");
 751         return LOOKUP_NONE;
 752     } else if (!p->digest->flags.needed) {
 753         debugs(15, 5, "peerDigestLookup: note need");
 754         peerDigestNeeded(p->digest);
 755         return LOOKUP_NONE;
 756     } else if (!p->digest->flags.usable) {
 757         debugs(15, 5, "peerDigestLookup: !ready && " << (p->digest->flags.requested ? "" : "!") << "requested");
 758         return LOOKUP_NONE;
 759     }
 760
 761     debugs(15, 5, "peerDigestLookup: OK to lookup peer " << p->host);
 762     assert(p->digest->cd);
 763     /* does digest predict a hit? */
 764
 765     if (!p->digest->cd->contains(key))
 766         return LOOKUP_MISS;
 767
 768     debugs(15, 5, "peerDigestLookup: peer " << p->host << " says HIT!");
 769
 770     return LOOKUP_HIT;
 771
 772 #endif
 773
 774     return LOOKUP_NONE;
 775 }
 776
 777 /* select best CachePeer based on cache digests */
 778 CachePeer *
 779 neighborsDigestSelect(HttpRequest * request)
 780 {
 781     CachePeer *best_p = NULL;
 782 #if USE_CACHE_DIGESTS
 783
 784     int best_rtt = 0;
 785     int choice_count = 0;
 786     int ichoice_count = 0;
 787     CachePeer *p;
 788     int p_rtt;
 789     int i;
 790
 791     if (!request->flags.hierarchical)
 792         return NULL;
 793
 794     storeKeyPublicByRequest(request);
 795
 796     for (i = 0, p = first_ping; i++ < Config.npeers; p = p->next) {
 797         lookup_t lookup;
 798
 799         if (!p)
 800             p = Config.peers;
 801
 802         if (i == 1)
 803             first_ping = p;
 804
 805         lookup = peerDigestLookup(p, request);
 806
 807         if (lookup == LOOKUP_NONE)
 808             continue;
 809
 810         ++choice_count;
 811
 812         if (lookup == LOOKUP_MISS)
 813             continue;
 814
 815         p_rtt = netdbHostRtt(p->host);
 816
 817         debugs(15, 5, "neighborsDigestSelect: peer " << p->host << " rtt: " << p_rtt);
 818
 819         /* is this CachePeer better than others in terms of rtt ? */
 820         if (!best_p || (p_rtt && p_rtt < best_rtt)) {
 821             best_p = p;
 822             best_rtt = p_rtt;
 823
 824             if (p_rtt)      /* informative choice (aka educated guess) */
 825                 ++ichoice_count;
 826
 827             debugs(15, 4, "neighborsDigestSelect: peer " << p->host << " leads with rtt " << best_rtt);
 828         }
 829     }
 830
 831     debugs(15, 4, "neighborsDigestSelect: choices: " << choice_count << " (" << ichoice_count << ")");
 832     peerNoteDigestLookup(request, best_p,
 833                          best_p ? LOOKUP_HIT : (choice_count ? LOOKUP_MISS : LOOKUP_NONE));
 834     request->hier.n_choices = choice_count;
 835     request->hier.n_ichoices = ichoice_count;
 836 #endif
 837
 838     return best_p;
 839 }
 840
 841 void
 842 peerNoteDigestLookup(HttpRequest * request, CachePeer * p, lookup_t lookup)
 843 {
 844 #if USE_CACHE_DIGESTS
 845     if (p)
 846         strncpy(request->hier.cd_host, p->host, sizeof(request->hier.cd_host)-1);
 847     else
 848         *request->hier.cd_host = '\0';
 849
 850     request->hier.cd_lookup = lookup;
 851     debugs(15, 4, "peerNoteDigestLookup: peer " << (p? p->host : "<none>") << ", lookup: " << lookup_t_str[lookup]  );
 852 #endif
 853 }
 854
 855 static void
 856 neighborAlive(CachePeer * p, const MemObject *, const icp_common_t * header)
 857 {
 858     peerAlive(p);
 859     ++ p->stats.pings_acked;
 860
 861     if ((icp_opcode) header->opcode <= ICP_END)
 862         ++ p->icp.counts[header->opcode];
 863
 864     p->icp.version = (int) header->version;
 865 }
 866
 867 static void
 868 neighborUpdateRtt(CachePeer * p, MemObject * mem)
 869 {
 870     int rtt, rtt_av_factor;
 871
 872     if (!mem)
 873         return;
 874
 875     if (!mem->start_ping.tv_sec)
 876         return;
 877
 878     rtt = tvSubMsec(mem->start_ping, current_time);
 879
 880     if (rtt < 1 || rtt > 10000)
 881         return;
 882
 883     rtt_av_factor = RTT_AV_FACTOR;
 884
 885     if (p->options.weighted_roundrobin)
 886         rtt_av_factor = RTT_BACKGROUND_AV_FACTOR;
 887
 888     p->stats.rtt = Math::intAverage(p->stats.rtt, rtt, p->stats.pings_acked, rtt_av_factor);
 889 }
 890
 891 #if USE_HTCP
 892 static void
 893 neighborAliveHtcp(CachePeer * p, const MemObject *, const HtcpReplyData * htcp)
 894 {
 895     peerAlive(p);
 896     ++ p->stats.pings_acked;
 897     ++ p->htcp.counts[htcp->hit ? 1 : 0];
 898     p->htcp.version = htcp->version;
 899 }
 900
 901 #endif
 902
 903 static void
 904 neighborCountIgnored(CachePeer * p)
 905 {
 906     if (p == NULL)
 907         return;
 908
 909     ++ p->stats.ignored_replies;
 910
 911     ++NLateReplies;
 912 }
 913
 914 static CachePeer *non_peers = NULL;
 915
 916 static void
 917 neighborIgnoreNonPeer(const Ip::Address &from, icp_opcode opcode)
 918 {
 919     CachePeer *np;
 920
 921     for (np = non_peers; np; np = np->next) {
 922         if (np->in_addr != from)
 923             continue;
 924
 925         if (np->in_addr.port() != from.port())
 926             continue;
 927
 928         break;
 929     }
 930
 931     if (np == NULL) {
 932         np = new CachePeer;
 933         np->in_addr = from;
 934         np->icp.port = from.port();
 935         np->type = PEER_NONE;
 936         np->host = new char[MAX_IPSTRLEN];
 937         from.toStr(np->host,MAX_IPSTRLEN);
 938         np->next = non_peers;
 939         non_peers = np;
 940     }
 941
 942     ++ np->icp.counts[opcode];
 943
 944     if (isPowTen(++np->stats.ignored_replies))
 945         debugs(15, DBG_IMPORTANT, "WARNING: Ignored " << np->stats.ignored_replies << " replies from non-peer " << np->host);
 946 }
 947
 948 /* ignoreMulticastReply
 949  *
 950  * * We want to ignore replies from multicast peers if the
 951  * * cache_host_domain rules would normally prevent the CachePeer
 952  * * from being used
 953  */
 954 static int
 955 ignoreMulticastReply(CachePeer * p, MemObject * mem)
 956 {
 957     if (p == NULL)
 958         return 0;
 959
 960     if (!p->options.mcast_responder)
 961         return 0;
 962
 963     if (peerHTTPOkay(p, mem->request.getRaw()))
 964         return 0;
 965
 966     return 1;
 967 }
 968
 969 /**
 970  * I should attach these records to the entry.  We take the first
 971  * hit we get our wait until everyone misses.  The timeout handler
 972  * call needs to nip this shopping list or call one of the misses.
 973  *
 974  * If a hit process is already started, then sobeit
 975  */
 976 void
 977 neighborsUdpAck(const cache_key * key, icp_common_t * header, const Ip::Address &from)
 978 {
 979     CachePeer *p = NULL;
 980     StoreEntry *entry;
 981     MemObject *mem = NULL;
 982     peer_t ntype = PEER_NONE;
 983     icp_opcode opcode = (icp_opcode) header->opcode;
 984
 985     debugs(15, 6, "neighborsUdpAck: opcode " << opcode << " '" << storeKeyText(key) << "'");
 986
 987     if (NULL != (entry = Store::Root().get(key)))
 988         mem = entry->mem_obj;
 989
 990     if ((p = whichPeer(from)))
 991         neighborAlive(p, mem, header);
 992
 993     if (opcode > ICP_END)
 994         return;
 995
 996     const char *opcode_d = icp_opcode_str[opcode];
 997
 998     if (p)
 999         neighborUpdateRtt(p, mem);
1000
1001     /* Does the entry exist? */
1002     if (NULL == entry) {
1003         debugs(12, 3, "neighborsUdpAck: Cache key '" << storeKeyText(key) << "' not found");
1004         neighborCountIgnored(p);
1005         return;
1006     }
1007
1008     /* check if someone is already fetching it */
1009     if (EBIT_TEST(entry->flags, ENTRY_DISPATCHED)) {
1010         debugs(15, 3, "neighborsUdpAck: '" << storeKeyText(key) << "' already being fetched.");
1011         neighborCountIgnored(p);
1012         return;
1013     }
1014
1015     if (mem == NULL) {
1016         debugs(15, 2, "Ignoring " << opcode_d << " for missing mem_obj: " << storeKeyText(key));
1017         neighborCountIgnored(p);
1018         return;
1019     }
1020
1021     if (entry->ping_status != PING_WAITING) {
1022         debugs(15, 2, "neighborsUdpAck: Late " << opcode_d << " for " << storeKeyText(key));
1023         neighborCountIgnored(p);
1024         return;
1025     }
1026
1027     if (!entry->locked()) {
1028         // TODO: many entries are unlocked; why is this reported at level 1?
1029         debugs(12, DBG_IMPORTANT, "neighborsUdpAck: '" << storeKeyText(key) << "' has no locks");
1030         neighborCountIgnored(p);
1031         return;
1032     }
1033
1034     debugs(15, 3, "neighborsUdpAck: " << opcode_d << " for '" << storeKeyText(key) << "' from " << (p ? p->host : "source") << " ");
1035
1036     if (p) {
1037         ntype = neighborType(p, mem->request->url);
1038     }
1039
1040     if (ignoreMulticastReply(p, mem)) {
1041         neighborCountIgnored(p);
1042     } else if (opcode == ICP_MISS) {
1043         if (p == NULL) {
1044             neighborIgnoreNonPeer(from, opcode);
1045         } else {
1046             mem->ping_reply_callback(p, ntype, AnyP::PROTO_ICP, header, mem->ircb_data);
1047         }
1048     } else if (opcode == ICP_HIT) {
1049         if (p == NULL) {
1050             neighborIgnoreNonPeer(from, opcode);
1051         } else {
1052             header->opcode = ICP_HIT;
1053             mem->ping_reply_callback(p, ntype, AnyP::PROTO_ICP, header, mem->ircb_data);
1054         }
1055     } else if (opcode == ICP_DECHO) {
1056         if (p == NULL) {
1057             neighborIgnoreNonPeer(from, opcode);
1058         } else if (ntype == PEER_SIBLING) {
1059             debug_trap("neighborsUdpAck: Found non-ICP cache as SIBLING\n");
1060             debug_trap("neighborsUdpAck: non-ICP neighbors must be a PARENT\n");
1061         } else {
1062             mem->ping_reply_callback(p, ntype, AnyP::PROTO_ICP, header, mem->ircb_data);
1063         }
1064     } else if (opcode == ICP_SECHO) {
1065         if (p) {
1066             debugs(15, DBG_IMPORTANT, "Ignoring SECHO from neighbor " << p->host);
1067             neighborCountIgnored(p);
1068         } else {
1069             debugs(15, DBG_IMPORTANT, "Unsolicited SECHO from " << from);
1070         }
1071     } else if (opcode == ICP_DENIED) {
1072         if (p == NULL) {
1073             neighborIgnoreNonPeer(from, opcode);
1074         } else if (p->stats.pings_acked > 100) {
1075             if (100 * p->icp.counts[ICP_DENIED] / p->stats.pings_acked > 95) {
1076                 debugs(15, DBG_CRITICAL, "95%% of replies from '" << p->host << "' are UDP_DENIED");
1077                 debugs(15, DBG_CRITICAL, "Disabling '" << p->host << "', please check your configuration.");
1078                 neighborRemove(p);
1079                 p = NULL;
1080             } else {
1081                 neighborCountIgnored(p);
1082             }
1083         }
1084     } else if (opcode == ICP_MISS_NOFETCH) {
1085         mem->ping_reply_callback(p, ntype, AnyP::PROTO_ICP, header, mem->ircb_data);
1086     } else {
1087         debugs(15, DBG_CRITICAL, "neighborsUdpAck: Unexpected ICP reply: " << opcode_d);
1088     }
1089 }
1090
1091 CachePeer *
1092 peerFindByName(const char *name)
1093 {
1094     CachePeer *p = NULL;
1095
1096     for (p = Config.peers; p; p = p->next) {
1097         if (!strcasecmp(name, p->name))
1098             break;
1099     }
1100
1101     return p;
1102 }
1103
1104 CachePeer *
1105 peerFindByNameAndPort(const char *name, unsigned short port)
1106 {
1107     CachePeer *p = NULL;
1108
1109     for (p = Config.peers; p; p = p->next) {
1110         if (strcasecmp(name, p->name))
1111             continue;
1112
1113         if (port != p->http_port)
1114             continue;
1115
1116         break;
1117     }
1118
1119     return p;
1120 }
1121
1122 int
1123 neighborUp(const CachePeer * p)
1124 {
1125     if (!p->tcp_up) {
1126         peerProbeConnect(const_cast<CachePeer*>(p));
1127         return 0;
1128     }
1129
1130     /*
1131      * The CachePeer can not be UP if we don't have any IP addresses
1132      * for it.
1133      */
1134     if (0 == p->n_addresses) {
1135         debugs(15, 8, "neighborUp: DOWN (no-ip): " << p->host << " (" << p->in_addr << ")");
1136         return 0;
1137     }
1138
1139     if (p->options.no_query) {
1140         debugs(15, 8, "neighborUp: UP (no-query): " << p->host << " (" << p->in_addr << ")");
1141         return 1;
1142     }
1143
1144     if (p->stats.probe_start != 0 &&
1145             squid_curtime - p->stats.probe_start > Config.Timeout.deadPeer) {
1146         debugs(15, 8, "neighborUp: DOWN (dead): " << p->host << " (" << p->in_addr << ")");
1147         return 0;
1148     }
1149
1150     debugs(15, 8, "neighborUp: UP: " << p->host << " (" << p->in_addr << ")");
1151     return 1;
1152 }
1153
1154 void
1155 peerNoteDigestGone(CachePeer * p)
1156 {
1157 #if USE_CACHE_DIGESTS
1158     cbdataReferenceDone(p->digest);
1159 #endif
1160 }
1161
1162 /// \returns the effective connect timeout for this peer
1163 time_t
1164 peerConnectTimeout(const CachePeer *peer)
1165 {
1166     return peer->connect_timeout_raw > 0 ?
1167            peer->connect_timeout_raw : Config.Timeout.peer_connect;
1168 }
1169
1170 time_t
1171 positiveTimeout(const time_t timeout)
1172 {
1173     return max(static_cast<time_t>(1), timeout);
1174 }
1175
1176 static void
1177 peerDNSConfigure(const ipcache_addrs *ia, const Dns::LookupDetails &, void *data)
1178 {
1179     // TODO: connections to no-longer valid IP addresses should be
1180     // closed when we can detect such IP addresses.
1181
1182     CachePeer *p = (CachePeer *)data;
1183
1184     if (p->n_addresses == 0) {
1185         debugs(15, DBG_IMPORTANT, "Configuring " << neighborTypeStr(p) << " " << p->host << "/" << p->http_port << "/" << p->icp.port);
1186
1187         if (p->type == PEER_MULTICAST)
1188             debugs(15, DBG_IMPORTANT, "    Multicast TTL = " << p->mcast.ttl);
1189     }
1190
1191     p->n_addresses = 0;
1192
1193     if (ia == NULL) {
1194         debugs(0, DBG_CRITICAL, "WARNING: DNS lookup for '" << p->host << "' failed!");
1195         return;
1196     }
1197
1198     if (ia->empty()) {
1199         debugs(0, DBG_CRITICAL, "WARNING: No IP address found for '" << p->host << "'!");
1200         return;
1201     }
1202
1203     for (const auto &ip: ia->goodAndBad()) { // TODO: Consider using just good().
1204         if (p->n_addresses < PEER_MAX_ADDRESSES) {
1205             const auto idx = p->n_addresses++;
1206             p->addresses[idx] = ip;
1207             debugs(15, 2, "--> IP address #" << idx << ": " << p->addresses[idx]);
1208         } else {
1209             debugs(15, 3, "ignoring remaining " << (ia->size() - p->n_addresses) << " ips");
1210             break;
1211         }
1212     }
1213
1214     p->in_addr.setEmpty();
1215     p->in_addr = p->addresses[0];
1216     p->in_addr.port(p->icp.port);
1217
1218     peerProbeConnect(p, true); // detect any died or revived peers ASAP
1219
1220     if (p->type == PEER_MULTICAST)
1221         peerCountMcastPeersSchedule(p, 10);
1222
1223 #if USE_ICMP
1224     if (p->type != PEER_MULTICAST && IamWorkerProcess())
1225         if (!p->options.no_netdb_exchange)
1226             eventAddIsh("netdbExchangeStart", netdbExchangeStart, p, 30.0, 1);
1227 #endif
1228
1229     if (p->standby.mgr.valid())
1230         PeerPoolMgr::Checkpoint(p->standby.mgr, "resolved peer");
1231 }
1232
1233 static void
1234 peerRefreshDNS(void *data)
1235 {
1236     CachePeer *p = NULL;
1237
1238     if (eventFind(peerRefreshDNS, NULL))
1239         eventDelete(peerRefreshDNS, NULL);
1240
1241     if (!data && 0 == stat5minClientRequests()) {
1242         /* no recent client traffic, wait a bit */
1243         eventAddIsh("peerRefreshDNS", peerRefreshDNS, NULL, 180.0, 1);
1244         return;
1245     }
1246
1247     for (p = Config.peers; p; p = p->next)
1248         ipcache_nbgethostbyname(p->host, peerDNSConfigure, p);
1249
1250     /* Reconfigure the peers every hour */
1251     eventAddIsh("peerRefreshDNS", peerRefreshDNS, NULL, 3600.0, 1);
1252 }
1253
1254 static void
1255 peerConnectFailedSilent(CachePeer * p)
1256 {
1257     p->stats.last_connect_failure = squid_curtime;
1258
1259     if (!p->tcp_up) {
1260         debugs(15, 2, "TCP connection to " << p->host << "/" << p->http_port <<
1261                " dead");
1262         return;
1263     }
1264
1265     -- p->tcp_up;
1266
1267     if (!p->tcp_up) {
1268         debugs(15, DBG_IMPORTANT, "Detected DEAD " << neighborTypeStr(p) << ": " << p->name);
1269         p->stats.logged_state = PEER_DEAD;
1270     }
1271 }
1272
1273 void
1274 peerConnectFailed(CachePeer *p)
1275 {
1276     debugs(15, DBG_IMPORTANT, "TCP connection to " << p->host << "/" << p->http_port << " failed");
1277     peerConnectFailedSilent(p);
1278 }
1279
1280 void
1281 peerConnectSucceded(CachePeer * p)
1282 {
1283     if (!p->tcp_up) {
1284         debugs(15, 2, "TCP connection to " << p->host << "/" << p->http_port << " succeded");
1285         p->tcp_up = p->connect_fail_limit; // NP: so peerAlive(p) works properly.
1286         peerAlive(p);
1287         if (!p->n_addresses)
1288             ipcache_nbgethostbyname(p->host, peerDNSConfigure, p);
1289     } else
1290         p->tcp_up = p->connect_fail_limit;
1291 }
1292
1293 /// whether new TCP probes are currently banned
1294 static bool
1295 peerProbeIsBusy(const CachePeer *p)
1296 {
1297     if (p->testing_now > 0) {
1298         debugs(15, 8, "yes, probing " << p);
1299         return true;
1300     }
1301     if (squid_curtime - p->stats.last_connect_probe == 0) {
1302         debugs(15, 8, "yes, just probed " << p);
1303         return true;
1304     }
1305     return false;
1306 }
1307 /*
1308 * peerProbeConnect will be called on dead peers by neighborUp
1309 */
1310 static void
1311 peerProbeConnect(CachePeer *p, const bool reprobeIfBusy)
1312 {
1313     if (peerProbeIsBusy(p)) {
1314         p->reprobe = reprobeIfBusy;
1315         return;
1316     }
1317     p->reprobe = false;
1318
1319     const time_t ctimeout = peerConnectTimeout(p);
1320     /* for each IP address of this CachePeer. find one that we can connect to and probe it. */
1321     for (int i = 0; i < p->n_addresses; ++i) {
1322         Comm::ConnectionPointer conn = new Comm::Connection;
1323         conn->remote = p->addresses[i];
1324         conn->remote.port(p->http_port);
1325         conn->setPeer(p);
1326         getOutgoingAddress(NULL, conn);
1327
1328         ++ p->testing_now;
1329
1330         AsyncCall::Pointer call = commCbCall(15,3, "peerProbeConnectDone", CommConnectCbPtrFun(peerProbeConnectDone, p));
1331         Comm::ConnOpener *cs = new Comm::ConnOpener(conn, call, ctimeout);
1332         cs->setHost(p->host);
1333         AsyncJob::Start(cs);
1334     }
1335
1336     p->stats.last_connect_probe = squid_curtime;
1337 }
1338
1339 static void
1340 peerProbeConnectDone(const Comm::ConnectionPointer &conn, Comm::Flag status, int, void *data)
1341 {
1342     CachePeer *p = (CachePeer*)data;
1343
1344     if (status == Comm::OK) {
1345         peerConnectSucceded(p);
1346     } else {
1347         peerConnectFailedSilent(p);
1348     }
1349
1350     -- p->testing_now;
1351     conn->close();
1352     // TODO: log this traffic.
1353
1354     if (p->reprobe)
1355         peerProbeConnect(p);
1356 }
1357
1358 static void
1359 peerCountMcastPeersSchedule(CachePeer * p, time_t when)
1360 {
1361     if (p->mcast.flags.count_event_pending)
1362         return;
1363
1364     eventAdd("peerCountMcastPeersStart",
1365              peerCountMcastPeersStart,
1366              p,
1367              (double) when, 1);
1368
1369     p->mcast.flags.count_event_pending = true;
1370 }
1371
1372 static void
1373 peerCountMcastPeersStart(void *data)
1374 {
1375     // XXX: Do not create lots of complex fake objects (while abusing their
1376     // APIs) to pass around a few basic data points like start_ping and ping!
1377     CachePeer *p = (CachePeer *)data;
1378     MemObject *mem;
1379     icp_common_t *query;
1380     int reqnum;
1381     // TODO: use class URL instead of constructing and re-parsing a string
1382     LOCAL_ARRAY(char, url, MAX_URL);
1383     assert(p->type == PEER_MULTICAST);
1384     p->mcast.flags.count_event_pending = false;
1385     snprintf(url, MAX_URL, "http://");
1386     p->in_addr.toUrl(url+7, MAX_URL -8 );
1387     strcat(url, "/");
1388     const MasterXaction::Pointer mx = new MasterXaction(XactionInitiator::initPeerMcast);
1389     HttpRequest *req = HttpRequest::FromUrl(url, mx);
1390     assert(req != nullptr);
1391     StoreEntry *fake = storeCreateEntry(url, url, RequestFlags(), Http::METHOD_GET);
1392     const auto psstate = new PeerSelector(nullptr);
1393     psstate->request = req;
1394     HTTPMSGLOCK(psstate->request);
1395     psstate->entry = fake;
1396     psstate->peerCountMcastPeerXXX = cbdataReference(p);
1397     psstate->ping.start = current_time;
1398     mem = fake->mem_obj;
1399     mem->request = psstate->request;
1400     mem->start_ping = current_time;
1401     mem->ping_reply_callback = peerCountHandleIcpReply;
1402     mem->ircb_data = psstate;
1403     mcastSetTtl(icpOutgoingConn->fd, p->mcast.ttl);
1404     p->mcast.id = mem->id;
1405     reqnum = icpSetCacheKey((const cache_key *)fake->key);
1406     query = icp_common_t::CreateMessage(ICP_QUERY, 0, url, reqnum, 0);
1407     icpUdpSend(icpOutgoingConn->fd, p->in_addr, query, LOG_ICP_QUERY, 0);
1408     fake->ping_status = PING_WAITING;
1409     eventAdd("peerCountMcastPeersDone",
1410              peerCountMcastPeersDone,
1411              psstate,
1412              Config.Timeout.mcast_icp_query / 1000.0, 1);
1413     p->mcast.flags.counting = true;
1414     peerCountMcastPeersSchedule(p, MCAST_COUNT_RATE);
1415 }
1416
1417 static void
1418 peerCountMcastPeersDone(void *data)
1419 {
1420     const auto psstate = static_cast<PeerSelector*>(data);
1421     StoreEntry *fake = psstate->entry;
1422
1423     if (cbdataReferenceValid(psstate->peerCountMcastPeerXXX)) {
1424         CachePeer *p = (CachePeer *)psstate->peerCountMcastPeerXXX;
1425         p->mcast.flags.counting = false;
1426         p->mcast.avg_n_members = Math::doubleAverage(p->mcast.avg_n_members, (double) psstate->ping.n_recv, ++p->mcast.n_times_counted, 10);
1427         debugs(15, DBG_IMPORTANT, "Group " << p->host  << ": " << psstate->ping.n_recv  <<
1428                " replies, "<< std::setw(4)<< std::setprecision(2) <<
1429                p->mcast.avg_n_members <<" average, RTT " << p->stats.rtt);
1430         p->mcast.n_replies_expected = (int) p->mcast.avg_n_members;
1431     }
1432
1433     cbdataReferenceDone(psstate->peerCountMcastPeerXXX);
1434
1435     fake->abort(); // sets ENTRY_ABORTED and initiates releated cleanup
1436     fake->mem_obj->request = nullptr;
1437     fake->unlock("peerCountMcastPeersDone");
1438     delete psstate;
1439 }
1440
1441 static void
1442 peerCountHandleIcpReply(CachePeer * p, peer_t, AnyP::ProtocolType proto, void *, void *data)
1443 {
1444     const auto psstate = static_cast<PeerSelector*>(data);
1445     StoreEntry *fake = psstate->entry;
1446     assert(fake);
1447     MemObject *mem = fake->mem_obj;
1448     assert(mem);
1449     int rtt = tvSubMsec(mem->start_ping, current_time);
1450     assert(proto == AnyP::PROTO_ICP);
1451     ++ psstate->ping.n_recv;
1452     int rtt_av_factor = RTT_AV_FACTOR;
1453
1454     if (p->options.weighted_roundrobin)
1455         rtt_av_factor = RTT_BACKGROUND_AV_FACTOR;
1456
1457     p->stats.rtt = Math::intAverage(p->stats.rtt, rtt, psstate->ping.n_recv, rtt_av_factor);
1458 }
1459
1460 static void
1461 neighborDumpPeers(StoreEntry * sentry)
1462 {
1463     dump_peers(sentry, Config.peers);
1464 }
1465
1466 static void
1467 neighborDumpNonPeers(StoreEntry * sentry)
1468 {
1469     dump_peers(sentry, non_peers);
1470 }
1471
1472 void
1473 dump_peer_options(StoreEntry * sentry, CachePeer * p)
1474 {
1475     if (p->options.proxy_only)
1476         storeAppendPrintf(sentry, " proxy-only");
1477
1478     if (p->options.no_query)
1479         storeAppendPrintf(sentry, " no-query");
1480
1481     if (p->options.background_ping)
1482         storeAppendPrintf(sentry, " background-ping");
1483
1484     if (p->options.no_digest)
1485         storeAppendPrintf(sentry, " no-digest");
1486
1487     if (p->options.default_parent)
1488         storeAppendPrintf(sentry, " default");
1489
1490     if (p->options.roundrobin)
1491         storeAppendPrintf(sentry, " round-robin");
1492
1493     if (p->options.carp)
1494         storeAppendPrintf(sentry, " carp");
1495
1496 #if USE_AUTH
1497     if (p->options.userhash)
1498         storeAppendPrintf(sentry, " userhash");
1499 #endif
1500
1501     if (p->options.sourcehash)
1502         storeAppendPrintf(sentry, " sourcehash");
1503
1504     if (p->options.weighted_roundrobin)
1505         storeAppendPrintf(sentry, " weighted-round-robin");
1506
1507     if (p->options.mcast_responder)
1508         storeAppendPrintf(sentry, " multicast-responder");
1509
1510 #if PEER_MULTICAST_SIBLINGS
1511     if (p->options.mcast_siblings)
1512         storeAppendPrintf(sentry, " multicast-siblings");
1513 #endif
1514
1515     if (p->weight != 1)
1516         storeAppendPrintf(sentry, " weight=%d", p->weight);
1517
1518     if (p->options.closest_only)
1519         storeAppendPrintf(sentry, " closest-only");
1520
1521 #if USE_HTCP
1522     if (p->options.htcp) {
1523         storeAppendPrintf(sentry, " htcp");
1524         if (p->options.htcp_oldsquid || p->options.htcp_no_clr || p->options.htcp_no_purge_clr || p->options.htcp_only_clr) {
1525             bool doneopts = false;
1526             if (p->options.htcp_oldsquid) {
1527                 storeAppendPrintf(sentry, "oldsquid");
1528                 doneopts = true;
1529             }
1530             if (p->options.htcp_no_clr) {
1531                 storeAppendPrintf(sentry, "%sno-clr",(doneopts?",":"="));
1532                 doneopts = true;
1533             }
1534             if (p->options.htcp_no_purge_clr) {
1535                 storeAppendPrintf(sentry, "%sno-purge-clr",(doneopts?",":"="));
1536                 doneopts = true;
1537             }
1538             if (p->options.htcp_only_clr) {
1539                 storeAppendPrintf(sentry, "%sonly-clr",(doneopts?",":"="));
1540                 //doneopts = true; // uncomment if more opts are added
1541             }
1542         }
1543     }
1544 #endif
1545
1546     if (p->options.no_netdb_exchange)
1547         storeAppendPrintf(sentry, " no-netdb-exchange");
1548
1549 #if USE_DELAY_POOLS
1550     if (p->options.no_delay)
1551         storeAppendPrintf(sentry, " no-delay");
1552 #endif
1553
1554     if (p->login)
1555         storeAppendPrintf(sentry, " login=%s", p->login);
1556
1557     if (p->mcast.ttl > 0)
1558         storeAppendPrintf(sentry, " ttl=%d", p->mcast.ttl);
1559
1560     if (p->connect_timeout_raw > 0)
1561         storeAppendPrintf(sentry, " connect-timeout=%d", (int)p->connect_timeout_raw);
1562
1563     if (p->connect_fail_limit != PEER_TCP_MAGIC_COUNT)
1564         storeAppendPrintf(sentry, " connect-fail-limit=%d", p->connect_fail_limit);
1565
1566 #if USE_CACHE_DIGESTS
1567
1568     if (p->digest_url)
1569         storeAppendPrintf(sentry, " digest-url=%s", p->digest_url);
1570
1571 #endif
1572
1573     if (p->options.allow_miss)
1574         storeAppendPrintf(sentry, " allow-miss");
1575
1576     if (p->options.no_tproxy)
1577         storeAppendPrintf(sentry, " no-tproxy");
1578
1579     if (p->max_conn > 0)
1580         storeAppendPrintf(sentry, " max-conn=%d", p->max_conn);
1581     if (p->standby.limit > 0)
1582         storeAppendPrintf(sentry, " standby=%d", p->standby.limit);
1583
1584     if (p->options.originserver)
1585         storeAppendPrintf(sentry, " originserver");
1586
1587     if (p->domain)
1588         storeAppendPrintf(sentry, " forceddomain=%s", p->domain);
1589
1590     if (p->connection_auth == 0)
1591         storeAppendPrintf(sentry, " connection-auth=off");
1592     else if (p->connection_auth == 1)
1593         storeAppendPrintf(sentry, " connection-auth=on");
1594     else if (p->connection_auth == 2)
1595         storeAppendPrintf(sentry, " connection-auth=auto");
1596
1597     p->secure.dumpCfg(sentry,"tls-");
1598     storeAppendPrintf(sentry, "\n");
1599 }
1600
1601 static void
1602 dump_peers(StoreEntry * sentry, CachePeer * peers)
1603 {
1604     char ntoabuf[MAX_IPSTRLEN];
1605     int i;
1606
1607     if (peers == NULL)
1608         storeAppendPrintf(sentry, "There are no neighbors installed.\n");
1609
1610     for (CachePeer *e = peers; e; e = e->next) {
1611         assert(e->host != NULL);
1612         storeAppendPrintf(sentry, "\n%-11.11s: %s\n",
1613                           neighborTypeStr(e),
1614                           e->name);
1615         storeAppendPrintf(sentry, "Host       : %s/%d/%d\n",
1616                           e->host,
1617                           e->http_port,
1618                           e->icp.port);
1619         storeAppendPrintf(sentry, "Flags      :");
1620         dump_peer_options(sentry, e);
1621
1622         for (i = 0; i < e->n_addresses; ++i) {
1623             storeAppendPrintf(sentry, "Address[%d] : %s\n", i,
1624                               e->addresses[i].toStr(ntoabuf,MAX_IPSTRLEN) );
1625         }
1626
1627         storeAppendPrintf(sentry, "Status     : %s\n",
1628                           neighborUp(e) ? "Up" : "Down");
1629         storeAppendPrintf(sentry, "FETCHES    : %d\n", e->stats.fetches);
1630         storeAppendPrintf(sentry, "OPEN CONNS : %d\n", e->stats.conn_open);
1631         storeAppendPrintf(sentry, "AVG RTT    : %d msec\n", e->stats.rtt);
1632
1633         if (!e->options.no_query) {
1634             storeAppendPrintf(sentry, "LAST QUERY : %8d seconds ago\n",
1635                               (int) (squid_curtime - e->stats.last_query));
1636
1637             if (e->stats.last_reply > 0)
1638                 storeAppendPrintf(sentry, "LAST REPLY : %8d seconds ago\n",
1639                                   (int) (squid_curtime - e->stats.last_reply));
1640             else
1641                 storeAppendPrintf(sentry, "LAST REPLY : none received\n");
1642
1643             storeAppendPrintf(sentry, "PINGS SENT : %8d\n", e->stats.pings_sent);
1644
1645             storeAppendPrintf(sentry, "PINGS ACKED: %8d %3d%%\n",
1646                               e->stats.pings_acked,
1647                               Math::intPercent(e->stats.pings_acked, e->stats.pings_sent));
1648         }
1649
1650         storeAppendPrintf(sentry, "IGNORED    : %8d %3d%%\n", e->stats.ignored_replies, Math::intPercent(e->stats.ignored_replies, e->stats.pings_acked));
1651
1652         if (!e->options.no_query) {
1653             storeAppendPrintf(sentry, "Histogram of PINGS ACKED:\n");
1654 #if USE_HTCP
1655
1656             if (e->options.htcp) {
1657                 storeAppendPrintf(sentry, "\tMisses\t%8d %3d%%\n",
1658                                   e->htcp.counts[0],
1659                                   Math::intPercent(e->htcp.counts[0], e->stats.pings_acked));
1660                 storeAppendPrintf(sentry, "\tHits\t%8d %3d%%\n",
1661                                   e->htcp.counts[1],
1662                                   Math::intPercent(e->htcp.counts[1], e->stats.pings_acked));
1663             } else {
1664 #endif
1665
1666                 for (auto op : WholeEnum<icp_opcode>()) {
1667                     if (e->icp.counts[op] == 0)
1668                         continue;
1669
1670                     storeAppendPrintf(sentry, "    %12.12s : %8d %3d%%\n",
1671                                       icp_opcode_str[op],
1672                                       e->icp.counts[op],
1673                                       Math::intPercent(e->icp.counts[op], e->stats.pings_acked));
1674                 }
1675
1676 #if USE_HTCP
1677
1678             }
1679
1680 #endif
1681
1682         }
1683
1684         if (e->stats.last_connect_failure) {
1685             storeAppendPrintf(sentry, "Last failed connect() at: %s\n",
1686                               Time::FormatHttpd(e->stats.last_connect_failure));
1687         }
1688
1689         storeAppendPrintf(sentry, "keep-alive ratio: %d%%\n", Math::intPercent(e->stats.n_keepalives_recv, e->stats.n_keepalives_sent));
1690     }
1691 }
1692
1693 #if USE_HTCP
1694 void
1695 neighborsHtcpReply(const cache_key * key, HtcpReplyData * htcp, const Ip::Address &from)
1696 {
1697     StoreEntry *e = Store::Root().get(key);
1698     MemObject *mem = NULL;
1699     CachePeer *p;
1700     peer_t ntype = PEER_NONE;
1701     debugs(15, 6, "neighborsHtcpReply: " <<
1702            (htcp->hit ? "HIT" : "MISS") << " " <<
1703            storeKeyText(key)  );
1704
1705     if (NULL != e)
1706         mem = e->mem_obj;
1707
1708     if ((p = whichPeer(from)))
1709         neighborAliveHtcp(p, mem, htcp);
1710
1711     /* Does the entry exist? */
1712     if (NULL == e) {
1713         debugs(12, 3, "neighyborsHtcpReply: Cache key '" << storeKeyText(key) << "' not found");
1714         neighborCountIgnored(p);
1715         return;
1716     }
1717
1718     /* check if someone is already fetching it */
1719     if (EBIT_TEST(e->flags, ENTRY_DISPATCHED)) {
1720         debugs(15, 3, "neighborsUdpAck: '" << storeKeyText(key) << "' already being fetched.");
1721         neighborCountIgnored(p);
1722         return;
1723     }
1724
1725     if (mem == NULL) {
1726         debugs(15, 2, "Ignoring reply for missing mem_obj: " << storeKeyText(key));
1727         neighborCountIgnored(p);
1728         return;
1729     }
1730
1731     if (e->ping_status != PING_WAITING) {
1732         debugs(15, 2, "neighborsUdpAck: Entry " << storeKeyText(key) << " is not PING_WAITING");
1733         neighborCountIgnored(p);
1734         return;
1735     }
1736
1737     if (!e->locked()) {
1738         // TODO: many entries are unlocked; why is this reported at level 1?
1739         debugs(12, DBG_IMPORTANT, "neighborsUdpAck: '" << storeKeyText(key) << "' has no locks");
1740         neighborCountIgnored(p);
1741         return;
1742     }
1743
1744     if (p) {
1745         ntype = neighborType(p, mem->request->url);
1746         neighborUpdateRtt(p, mem);
1747     }
1748
1749     if (ignoreMulticastReply(p, mem)) {
1750         neighborCountIgnored(p);
1751         return;
1752     }
1753
1754     debugs(15, 3, "neighborsHtcpReply: e = " << e);
1755     mem->ping_reply_callback(p, ntype, AnyP::PROTO_HTCP, htcp, mem->ircb_data);
1756 }
1757
1758 /*
1759  * Send HTCP CLR messages to all peers configured to receive them.
1760  */
1761 void
1762 neighborsHtcpClear(StoreEntry * e, const char *uri, HttpRequest * req, const HttpRequestMethod &method, htcp_clr_reason reason)
1763 {
1764     CachePeer *p;
1765     char buf[128];
1766
1767     for (p = Config.peers; p; p = p->next) {
1768         if (!p->options.htcp) {
1769             continue;
1770         }
1771         if (p->options.htcp_no_clr) {
1772             continue;
1773         }
1774         if (p->options.htcp_no_purge_clr && reason == HTCP_CLR_PURGE) {
1775             continue;
1776         }
1777         debugs(15, 3, "neighborsHtcpClear: sending CLR to " << p->in_addr.toUrl(buf, 128));
1778         htcpClear(e, uri, req, method, p, reason);
1779     }
1780 }
1781
1782 #endif
1783