lib/learning-switch.c

   1 /*
   2  * Copyright (c) 2008, 2009, 2010 Nicira Networks.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18 #include "learning-switch.h"
  19
  20 #include <errno.h>
  21 #include <inttypes.h>
  22 #include <netinet/in.h>
  23 #include <stdlib.h>
  24 #include <time.h>
  25
  26 #include "flow.h"
  27 #include "mac-learning.h"
  28 #include "ofpbuf.h"
  29 #include "ofp-print.h"
  30 #include "ofp-util.h"
  31 #include "openflow/openflow.h"
  32 #include "poll-loop.h"
  33 #include "queue.h"
  34 #include "rconn.h"
  35 #include "stp.h"
  36 #include "timeval.h"
  37 #include "vconn.h"
  38 #include "xtoxll.h"
  39
  40 #define THIS_MODULE VLM_learning_switch
  41 #include "vlog.h"
  42
  43 enum port_state {
  44     P_DISABLED = 1 << 0,
  45     P_LISTENING = 1 << 1,
  46     P_LEARNING = 1 << 2,
  47     P_FORWARDING = 1 << 3,
  48     P_BLOCKING = 1 << 4
  49 };
  50
  51 struct lswitch {
  52     /* If nonnegative, the switch sets up flows that expire after the given
  53      * number of seconds (or never expire, if the value is OFP_FLOW_PERMANENT).
  54      * Otherwise, the switch processes every packet. */
  55     int max_idle;
  56
  57     unsigned long long int datapath_id;
  58     uint32_t capabilities;
  59     time_t last_features_request;
  60     struct mac_learning *ml;    /* NULL to act as hub instead of switch. */
  61     bool exact_flows;           /* Use exact-match flows? */
  62     bool action_normal;         /* Use OFPP_NORMAL? */
  63
  64     /* Number of outgoing queued packets on the rconn. */
  65     struct rconn_packet_counter *queued;
  66
  67     /* Spanning tree protocol implementation.
  68      *
  69      * We implement STP states by, whenever a port's STP state changes,
  70      * querying all the flows on the switch and then deleting any of them that
  71      * are inappropriate for a port's STP state. */
  72     long long int next_query;   /* Next time at which to query all flows. */
  73     long long int last_query;   /* Last time we sent a query. */
  74     long long int last_reply;   /* Last time we received a query reply. */
  75     unsigned int port_states[STP_MAX_PORTS];
  76     uint32_t query_xid;         /* XID used for query. */
  77     int n_flows, n_no_recv, n_no_send;
  78 };
  79
  80 /* The log messages here could actually be useful in debugging, so keep the
  81  * rate limit relatively high. */
  82 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(30, 300);
  83
  84 static void queue_tx(struct lswitch *, struct rconn *, struct ofpbuf *);
  85 static void send_features_request(struct lswitch *, struct rconn *);
  86 static void schedule_query(struct lswitch *, long long int delay);
  87 static bool may_learn(const struct lswitch *, uint16_t port_no);
  88 static bool may_recv(const struct lswitch *, uint16_t port_no,
  89                      bool any_actions);
  90 static bool may_send(const struct lswitch *, uint16_t port_no);
  91
  92 typedef void packet_handler_func(struct lswitch *, struct rconn *, void *);
  93 static packet_handler_func process_switch_features;
  94 static packet_handler_func process_packet_in;
  95 static packet_handler_func process_echo_request;
  96 static packet_handler_func process_port_status;
  97 static packet_handler_func process_phy_port;
  98 static packet_handler_func process_stats_reply;
  99
 100 /* Creates and returns a new learning switch.
 101  *
 102  * If 'learn_macs' is true, the new switch will learn the ports on which MAC
 103  * addresses appear.  Otherwise, the new switch will flood all packets.
 104  *
 105  * If 'max_idle' is nonnegative, the new switch will set up flows that expire
 106  * after the given number of seconds (or never expire, if 'max_idle' is
 107  * OFP_FLOW_PERMANENT).  Otherwise, the new switch will process every packet.
 108  *
 109  * 'rconn' is used to send out an OpenFlow features request. */
 110 struct lswitch *
 111 lswitch_create(struct rconn *rconn, bool learn_macs,
 112                bool exact_flows, int max_idle, bool action_normal)
 113 {
 114     struct lswitch *sw;
 115     size_t i;
 116
 117     sw = xzalloc(sizeof *sw);
 118     sw->max_idle = max_idle;
 119     sw->datapath_id = 0;
 120     sw->last_features_request = time_now() - 1;
 121     sw->ml = learn_macs ? mac_learning_create() : NULL;
 122     sw->action_normal = action_normal;
 123     sw->exact_flows = exact_flows;
 124     sw->queued = rconn_packet_counter_create();
 125     sw->next_query = LLONG_MIN;
 126     sw->last_query = LLONG_MIN;
 127     sw->last_reply = LLONG_MIN;
 128     for (i = 0; i < STP_MAX_PORTS; i++) {
 129         sw->port_states[i] = P_DISABLED;
 130     }
 131     send_features_request(sw, rconn);
 132     return sw;
 133 }
 134
 135 /* Destroys 'sw'. */
 136 void
 137 lswitch_destroy(struct lswitch *sw)
 138 {
 139     if (sw) {
 140         mac_learning_destroy(sw->ml);
 141         rconn_packet_counter_destroy(sw->queued);
 142         free(sw);
 143     }
 144 }
 145
 146 /* Takes care of necessary 'sw' activity, except for receiving packets (which
 147  * the caller must do). */
 148 void
 149 lswitch_run(struct lswitch *sw, struct rconn *rconn)
 150 {
 151     long long int now = time_msec();
 152
 153     if (sw->ml) {
 154         mac_learning_run(sw->ml, NULL);
 155     }
 156
 157     /* If we're waiting for more replies, keeping waiting for up to 10 s. */
 158     if (sw->last_reply != LLONG_MIN) {
 159         if (now - sw->last_reply > 10000) {
 160             VLOG_ERR_RL(&rl, "%016llx: No more flow stat replies last 10 s",
 161                         sw->datapath_id);
 162             sw->last_reply = LLONG_MIN;
 163             sw->last_query = LLONG_MIN;
 164             schedule_query(sw, 0);
 165         } else {
 166             return;
 167         }
 168     }
 169
 170     /* If we're waiting for any reply at all, keep waiting for up to 10 s. */
 171     if (sw->last_query != LLONG_MIN) {
 172         if (now - sw->last_query > 10000) {
 173             VLOG_ERR_RL(&rl, "%016llx: No flow stat replies in last 10 s",
 174                         sw->datapath_id);
 175             sw->last_query = LLONG_MIN;
 176             schedule_query(sw, 0);
 177         } else {
 178             return;
 179         }
 180     }
 181
 182     /* If it's time to send another query, do so. */
 183     if (sw->next_query != LLONG_MIN && now >= sw->next_query) {
 184         sw->next_query = LLONG_MIN;
 185         if (!rconn_is_connected(rconn)) {
 186             schedule_query(sw, 1000);
 187         } else {
 188             struct ofp_stats_request *osr;
 189             struct ofp_flow_stats_request *ofsr;
 190             struct ofpbuf *b;
 191             int error;
 192
 193             VLOG_DBG("%016llx: Sending flow stats request to implement STP",
 194                      sw->datapath_id);
 195
 196             sw->last_query = now;
 197             sw->query_xid = random_uint32();
 198             sw->n_flows = 0;
 199             sw->n_no_recv = 0;
 200             sw->n_no_send = 0;
 201             osr = make_openflow_xid(sizeof *osr + sizeof *ofsr,
 202                                     OFPT_STATS_REQUEST, sw->query_xid, &b);
 203             osr->type = htons(OFPST_FLOW);
 204             osr->flags = htons(0);
 205             ofsr = (struct ofp_flow_stats_request *) osr->body;
 206             ofsr->match.wildcards = htonl(OFPFW_ALL);
 207             ofsr->table_id = 0xff;
 208             ofsr->out_port = htons(OFPP_NONE);
 209
 210             error = rconn_send(rconn, b, NULL);
 211             if (error) {
 212                 VLOG_WARN_RL(&rl, "%016llx: sending flow stats request "
 213                              "failed: %s", sw->datapath_id, strerror(error));
 214                 ofpbuf_delete(b);
 215                 schedule_query(sw, 1000);
 216             }
 217         }
 218     }
 219 }
 220
 221 static void
 222 wait_timeout(long long int started)
 223 {
 224     poll_timer_wait_until(started + 10000);
 225 }
 226
 227 void
 228 lswitch_wait(struct lswitch *sw)
 229 {
 230     if (sw->ml) {
 231         mac_learning_wait(sw->ml);
 232     }
 233
 234     if (sw->last_reply != LLONG_MIN) {
 235         wait_timeout(sw->last_reply);
 236     } else if (sw->last_query != LLONG_MIN) {
 237         wait_timeout(sw->last_query);
 238     }
 239 }
 240
 241 /* Processes 'msg', which should be an OpenFlow received on 'rconn', according
 242  * to the learning switch state in 'sw'.  The most likely result of processing
 243  * is that flow-setup and packet-out OpenFlow messages will be sent out on
 244  * 'rconn'.  */
 245 void
 246 lswitch_process_packet(struct lswitch *sw, struct rconn *rconn,
 247                        const struct ofpbuf *msg)
 248 {
 249     struct processor {
 250         uint8_t type;
 251         size_t min_size;
 252         packet_handler_func *handler;
 253     };
 254     static const struct processor processors[] = {
 255         {
 256             OFPT_ECHO_REQUEST,
 257             sizeof(struct ofp_header),
 258             process_echo_request
 259         },
 260         {
 261             OFPT_FEATURES_REPLY,
 262             sizeof(struct ofp_switch_features),
 263             process_switch_features
 264         },
 265         {
 266             OFPT_PACKET_IN,
 267             offsetof(struct ofp_packet_in, data),
 268             process_packet_in
 269         },
 270         {
 271             OFPT_PORT_STATUS,
 272             sizeof(struct ofp_port_status),
 273             process_port_status
 274         },
 275         {
 276             OFPT_STATS_REPLY,
 277             offsetof(struct ofp_stats_reply, body),
 278             process_stats_reply
 279         },
 280         {
 281             OFPT_FLOW_REMOVED,
 282             sizeof(struct ofp_flow_removed),
 283             NULL
 284         },
 285     };
 286     const size_t n_processors = ARRAY_SIZE(processors);
 287     const struct processor *p;
 288     struct ofp_header *oh;
 289
 290     oh = msg->data;
 291     if (sw->datapath_id == 0
 292         && oh->type != OFPT_ECHO_REQUEST
 293         && oh->type != OFPT_FEATURES_REPLY) {
 294         send_features_request(sw, rconn);
 295         return;
 296     }
 297
 298     for (p = processors; p < &processors[n_processors]; p++) {
 299         if (oh->type == p->type) {
 300             if (msg->size < p->min_size) {
 301                 VLOG_WARN_RL(&rl, "%016llx: %s: too short (%zu bytes) for "
 302                              "type %"PRIu8" (min %zu)", sw->datapath_id,
 303                              rconn_get_name(rconn), msg->size, oh->type,
 304                              p->min_size);
 305                 return;
 306             }
 307             if (p->handler) {
 308                 (p->handler)(sw, rconn, msg->data);
 309             }
 310             return;
 311         }
 312     }
 313     if (VLOG_IS_DBG_ENABLED()) {
 314         char *p = ofp_to_string(msg->data, msg->size, 2);
 315         VLOG_DBG_RL(&rl, "%016llx: OpenFlow packet ignored: %s",
 316                     sw->datapath_id, p);
 317         free(p);
 318     }
 319 }
 320 \f
 321 static void
 322 send_features_request(struct lswitch *sw, struct rconn *rconn)
 323 {
 324     time_t now = time_now();
 325     if (now >= sw->last_features_request + 1) {
 326         struct ofpbuf *b;
 327         struct ofp_switch_config *osc;
 328
 329         /* Send OFPT_FEATURES_REQUEST. */
 330         make_openflow(sizeof(struct ofp_header), OFPT_FEATURES_REQUEST, &b);
 331         queue_tx(sw, rconn, b);
 332
 333         /* Send OFPT_SET_CONFIG. */
 334         osc = make_openflow(sizeof *osc, OFPT_SET_CONFIG, &b);
 335         osc->miss_send_len = htons(OFP_DEFAULT_MISS_SEND_LEN);
 336         queue_tx(sw, rconn, b);
 337
 338         sw->last_features_request = now;
 339     }
 340 }
 341
 342 static void
 343 queue_tx(struct lswitch *sw, struct rconn *rconn, struct ofpbuf *b)
 344 {
 345     int retval = rconn_send_with_limit(rconn, b, sw->queued, 10);
 346     if (retval && retval != ENOTCONN) {
 347         if (retval == EAGAIN) {
 348             VLOG_INFO_RL(&rl, "%016llx: %s: tx queue overflow",
 349                          sw->datapath_id, rconn_get_name(rconn));
 350         } else {
 351             VLOG_WARN_RL(&rl, "%016llx: %s: send: %s",
 352                          sw->datapath_id, rconn_get_name(rconn),
 353                          strerror(retval));
 354         }
 355     }
 356 }
 357
 358 static void
 359 schedule_query(struct lswitch *sw, long long int delay)
 360 {
 361     long long int now = time_msec();
 362     if (sw->next_query == LLONG_MIN || sw->next_query > now + delay) {
 363         sw->next_query = now + delay;
 364     }
 365 }
 366
 367 static void
 368 process_switch_features(struct lswitch *sw, struct rconn *rconn, void *osf_)
 369 {
 370     struct ofp_switch_features *osf = osf_;
 371     size_t n_ports = ((ntohs(osf->header.length)
 372                        - offsetof(struct ofp_switch_features, ports))
 373                       / sizeof *osf->ports);
 374     size_t i;
 375
 376     sw->datapath_id = ntohll(osf->datapath_id);
 377     sw->capabilities = ntohl(osf->capabilities);
 378     for (i = 0; i < n_ports; i++) {
 379         process_phy_port(sw, rconn, &osf->ports[i]);
 380     }
 381     if (sw->capabilities & OFPC_STP) {
 382         schedule_query(sw, 1000);
 383     }
 384 }
 385
 386 static void
 387 process_packet_in(struct lswitch *sw, struct rconn *rconn, void *opi_)
 388 {
 389     struct ofp_packet_in *opi = opi_;
 390     uint16_t in_port = ntohs(opi->in_port);
 391     uint16_t out_port = OFPP_FLOOD;
 392
 393     size_t pkt_ofs, pkt_len;
 394     struct ofpbuf pkt;
 395     flow_t flow;
 396
 397     /* Extract flow data from 'opi' into 'flow'. */
 398     pkt_ofs = offsetof(struct ofp_packet_in, data);
 399     pkt_len = ntohs(opi->header.length) - pkt_ofs;
 400     pkt.data = opi->data;
 401     pkt.size = pkt_len;
 402     flow_extract(&pkt, 0, in_port, &flow);
 403
 404     if (may_learn(sw, in_port) && sw->ml) {
 405         if (mac_learning_learn(sw->ml, flow.dl_src, 0, in_port,
 406                                GRAT_ARP_LOCK_NONE)) {
 407             VLOG_DBG_RL(&rl, "%016llx: learned that "ETH_ADDR_FMT" is on "
 408                         "port %"PRIu16, sw->datapath_id,
 409                         ETH_ADDR_ARGS(flow.dl_src), in_port);
 410         }
 411     }
 412
 413     /* Drop frames for reserved multicast addresses. */
 414     if (eth_addr_is_reserved(flow.dl_dst)) {
 415         goto drop_it;
 416     }
 417
 418     if (!may_recv(sw, in_port, false)) {
 419         /* STP prevents receiving anything on this port. */
 420         goto drop_it;
 421     }
 422
 423     if (sw->ml) {
 424         int learned_port = mac_learning_lookup(sw->ml, flow.dl_dst, 0, NULL);
 425         if (learned_port >= 0 && may_send(sw, learned_port)) {
 426             out_port = learned_port;
 427         }
 428     }
 429
 430     if (in_port == out_port) {
 431         /* Don't send out packets on their input ports. */
 432         goto drop_it;
 433     } else if (sw->max_idle >= 0 && (!sw->ml || out_port != OFPP_FLOOD)) {
 434         struct ofpbuf *buffer;
 435         struct ofp_flow_mod *ofm;
 436         uint32_t wildcards;
 437
 438         /* Check if we need to wildcard the flows. */
 439         if (!sw->exact_flows) {
 440             /* We can not wildcard all fields.
 441              * We need in_port to detect moves.
 442              * We need both SA and DA to do learning. */
 443             wildcards = (OFPFW_DL_TYPE | OFPFW_NW_SRC_MASK | OFPFW_NW_DST_MASK
 444                          | OFPFW_NW_PROTO | OFPFW_TP_SRC | OFPFW_TP_DST);
 445         } else {
 446             /* Exact match */
 447             wildcards = 0;
 448         }
 449
 450         /* Check if we need to use "NORMAL" action. */
 451         if (sw->action_normal && out_port != OFPP_FLOOD) {
 452             out_port = OFPP_NORMAL;
 453         }
 454
 455         /* The output port is known, or we always flood everything, so add a
 456          * new flow. */
 457         buffer = make_add_simple_flow(&flow, ntohl(opi->buffer_id),
 458                                       out_port, sw->max_idle);
 459         ofm = buffer->data;
 460         ofm->match.wildcards = htonl(wildcards);
 461         queue_tx(sw, rconn, buffer);
 462
 463         /* If the switch didn't buffer the packet, we need to send a copy. */
 464         if (ntohl(opi->buffer_id) == UINT32_MAX) {
 465             queue_tx(sw, rconn,
 466                      make_unbuffered_packet_out(&pkt, in_port, out_port));
 467         }
 468     } else {
 469         struct ofpbuf *b;
 470
 471         /* Check if we need to use "NORMAL" action. */
 472         if (sw->action_normal && out_port != OFPP_FLOOD) {
 473             out_port = OFPP_NORMAL;
 474         }
 475
 476         /* We don't know that MAC, or we don't set up flows.  Send along the
 477          * packet without setting up a flow. */
 478         if (ntohl(opi->buffer_id) == UINT32_MAX) {
 479             b = make_unbuffered_packet_out(&pkt, in_port, out_port);
 480         } else {
 481             b = make_buffered_packet_out(ntohl(opi->buffer_id),
 482                                          in_port, out_port);
 483         }
 484         queue_tx(sw, rconn, b);
 485     }
 486     return;
 487
 488 drop_it:
 489     if (sw->max_idle >= 0) {
 490         /* Set up a flow to drop packets. */
 491         queue_tx(sw, rconn, make_add_flow(&flow, ntohl(opi->buffer_id),
 492                                           sw->max_idle, 0));
 493     } else {
 494         /* Just drop the packet, since we don't set up flows at all.
 495          * XXX we should send a packet_out with no actions if buffer_id !=
 496          * UINT32_MAX, to avoid clogging the kernel buffers. */
 497     }
 498     return;
 499 }
 500
 501 static void
 502 process_echo_request(struct lswitch *sw, struct rconn *rconn, void *rq_)
 503 {
 504     struct ofp_header *rq = rq_;
 505     queue_tx(sw, rconn, make_echo_reply(rq));
 506 }
 507
 508 static void
 509 process_port_status(struct lswitch *sw, struct rconn *rconn, void *ops_)
 510 {
 511     struct ofp_port_status *ops = ops_;
 512     process_phy_port(sw, rconn, &ops->desc);
 513 }
 514
 515 static void
 516 process_phy_port(struct lswitch *sw, struct rconn *rconn OVS_UNUSED,
 517                  void *opp_)
 518 {
 519     const struct ofp_phy_port *opp = opp_;
 520     uint16_t port_no = ntohs(opp->port_no);
 521     if (sw->capabilities & OFPC_STP && port_no < STP_MAX_PORTS) {
 522         uint32_t config = ntohl(opp->config);
 523         uint32_t state = ntohl(opp->state);
 524         unsigned int *port_state = &sw->port_states[port_no];
 525         unsigned int new_port_state;
 526
 527         if (!(config & (OFPPC_NO_STP | OFPPC_PORT_DOWN))
 528             && !(state & OFPPS_LINK_DOWN))
 529         {
 530             switch (state & OFPPS_STP_MASK) {
 531             case OFPPS_STP_LISTEN:
 532                 new_port_state = P_LISTENING;
 533                 break;
 534             case OFPPS_STP_LEARN:
 535                 new_port_state = P_LEARNING;
 536                 break;
 537             case OFPPS_STP_FORWARD:
 538                 new_port_state = P_FORWARDING;
 539                 break;
 540             case OFPPS_STP_BLOCK:
 541                 new_port_state = P_BLOCKING;
 542                 break;
 543             default:
 544                 new_port_state = P_DISABLED;
 545                 break;
 546             }
 547         } else {
 548             new_port_state = P_FORWARDING;
 549         }
 550         if (*port_state != new_port_state) {
 551             *port_state = new_port_state;
 552             schedule_query(sw, 1000);
 553         }
 554     }
 555 }
 556
 557 static unsigned int
 558 get_port_state(const struct lswitch *sw, uint16_t port_no)
 559 {
 560     return (port_no >= STP_MAX_PORTS || !(sw->capabilities & OFPC_STP)
 561             ? P_FORWARDING
 562             : sw->port_states[port_no]);
 563 }
 564
 565 static bool
 566 may_learn(const struct lswitch *sw, uint16_t port_no)
 567 {
 568     return get_port_state(sw, port_no) & (P_LEARNING | P_FORWARDING);
 569 }
 570
 571 static bool
 572 may_recv(const struct lswitch *sw, uint16_t port_no, bool any_actions)
 573 {
 574     unsigned int state = get_port_state(sw, port_no);
 575     return !(any_actions
 576              ? state & (P_DISABLED | P_LISTENING | P_BLOCKING)
 577              : state & (P_DISABLED | P_LISTENING | P_BLOCKING | P_LEARNING));
 578 }
 579
 580 static bool
 581 may_send(const struct lswitch *sw, uint16_t port_no)
 582 {
 583     return get_port_state(sw, port_no) & P_FORWARDING;
 584 }
 585
 586 static void
 587 process_flow_stats(struct lswitch *sw, struct rconn *rconn,
 588                    const struct ofp_flow_stats *ofs)
 589 {
 590     const char *end = (char *) ofs + ntohs(ofs->length);
 591     bool delete = false;
 592
 593     /* Decide to delete the flow if it matches on an STP-disabled physical
 594      * port.  But don't delete it if the flow just drops all received packets,
 595      * because that's a perfectly reasonable thing to do for disabled physical
 596      * ports. */
 597     if (!(ofs->match.wildcards & htonl(OFPFW_IN_PORT))) {
 598         if (!may_recv(sw, ntohs(ofs->match.in_port),
 599                       end > (char *) ofs->actions)) {
 600             delete = true;
 601             sw->n_no_recv++;
 602         }
 603     }
 604
 605     /* Decide to delete the flow if it forwards to an STP-disabled physical
 606      * port. */
 607     if (!delete) {
 608         const struct ofp_action_header *a;
 609         size_t len;
 610
 611         for (a = ofs->actions; (char *) a < end; a += len / 8) {
 612             len = ntohs(a->len);
 613             if (len > end - (char *) a) {
 614                 VLOG_DBG_RL(&rl, "%016llx: action exceeds available space "
 615                             "(%zu > %td)",
 616                             sw->datapath_id, len, end - (char *) a);
 617                 break;
 618             } else if (len % 8) {
 619                 VLOG_DBG_RL(&rl, "%016llx: action length (%zu) not multiple "
 620                             "of 8 bytes", sw->datapath_id, len);
 621                 break;
 622             }
 623
 624             if (a->type == htons(OFPAT_OUTPUT)) {
 625                 struct ofp_action_output *oao = (struct ofp_action_output *) a;
 626                 if (!may_send(sw, ntohs(oao->port))) {
 627                     delete = true;
 628                     sw->n_no_send++;
 629                     break;
 630                 }
 631             }
 632         }
 633     }
 634
 635     /* Delete the flow. */
 636     if (delete) {
 637         struct ofp_flow_mod *ofm;
 638         struct ofpbuf *b;
 639
 640         ofm = make_openflow(offsetof(struct ofp_flow_mod, actions),
 641                             OFPT_FLOW_MOD, &b);
 642         ofm->match = ofs->match;
 643         ofm->command = OFPFC_DELETE_STRICT;
 644         rconn_send(rconn, b, NULL);
 645     }
 646 }
 647
 648 static void
 649 process_stats_reply(struct lswitch *sw, struct rconn *rconn, void *osr_)
 650 {
 651     struct ofp_stats_reply *osr = osr_;
 652     struct flow_stats_iterator i;
 653     const struct ofp_flow_stats *fs;
 654
 655     if (sw->last_query == LLONG_MIN
 656         || osr->type != htons(OFPST_FLOW)
 657         || osr->header.xid != sw->query_xid) {
 658         return;
 659     }
 660     for (fs = flow_stats_first(&i, osr); fs; fs = flow_stats_next(&i)) {
 661         sw->n_flows++;
 662         process_flow_stats(sw, rconn, fs);
 663     }
 664     if (!(osr->flags & htons(OFPSF_REPLY_MORE))) {
 665         VLOG_DBG("%016llx: Deleted %d of %d received flows to "
 666                  "implement STP, %d because of no-recv, %d because of "
 667                  "no-send", sw->datapath_id,
 668                  sw->n_no_recv + sw->n_no_send, sw->n_flows,
 669                  sw->n_no_recv, sw->n_no_send);
 670         sw->last_query = LLONG_MIN;
 671         sw->last_reply = LLONG_MIN;
 672     } else {
 673         sw->last_reply = time_msec();
 674     }
 675 }
 676