lib/learning-switch.c

   1 /*
   2  * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
   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 "byte-order.h"
  27 #include "classifier.h"
  28 #include "flow.h"
  29 #include "hmap.h"
  30 #include "mac-learning.h"
  31 #include "ofpbuf.h"
  32 #include "ofp-actions.h"
  33 #include "ofp-errors.h"
  34 #include "ofp-msgs.h"
  35 #include "ofp-parse.h"
  36 #include "ofp-print.h"
  37 #include "ofp-util.h"
  38 #include "openflow/openflow.h"
  39 #include "poll-loop.h"
  40 #include "rconn.h"
  41 #include "shash.h"
  42 #include "simap.h"
  43 #include "timeval.h"
  44 #include "vconn.h"
  45 #include "vlog.h"
  46
  47 VLOG_DEFINE_THIS_MODULE(learning_switch);
  48
  49 struct lswitch_port {
  50     struct hmap_node hmap_node; /* Hash node for port number. */
  51     ofp_port_t port_no;         /* OpenFlow port number. */
  52     uint32_t queue_id;          /* OpenFlow queue number. */
  53 };
  54
  55 enum lswitch_state {
  56     S_CONNECTING,               /* Waiting for connection to complete. */
  57     S_FEATURES_REPLY,           /* Waiting for features reply. */
  58     S_SWITCHING,                /* Switching flows. */
  59 };
  60
  61 struct lswitch {
  62     struct rconn *rconn;
  63     enum lswitch_state state;
  64
  65     /* If nonnegative, the switch sets up flows that expire after the given
  66      * number of seconds (or never expire, if the value is OFP_FLOW_PERMANENT).
  67      * Otherwise, the switch processes every packet. */
  68     int max_idle;
  69
  70     enum ofputil_protocol protocol;
  71     unsigned long long int datapath_id;
  72     struct mac_learning *ml;    /* NULL to act as hub instead of switch. */
  73     struct flow_wildcards wc;   /* Wildcards to apply to flows. */
  74     bool action_normal;         /* Use OFPP_NORMAL? */
  75
  76     /* Queue distribution. */
  77     uint32_t default_queue;     /* Default OpenFlow queue, or UINT32_MAX. */
  78     struct hmap queue_numbers;  /* Map from port number to lswitch_port. */
  79     struct shash queue_names;   /* Map from port name to lswitch_port. */
  80
  81     /* Number of outgoing queued packets on the rconn. */
  82     struct rconn_packet_counter *queued;
  83
  84     /* If true, do not reply to any messages from the switch (for debugging
  85      * fail-open mode). */
  86     bool mute;
  87
  88     /* Optional "flow mod" requests to send to the switch at connection time,
  89      * to set up the flow table. */
  90     const struct ofputil_flow_mod *default_flows;
  91     size_t n_default_flows;
  92     enum ofputil_protocol usable_protocols;
  93 };
  94
  95 /* The log messages here could actually be useful in debugging, so keep the
  96  * rate limit relatively high. */
  97 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(30, 300);
  98
  99 static void queue_tx(struct lswitch *, struct ofpbuf *);
 100 static void send_features_request(struct lswitch *);
 101
 102 static void lswitch_process_packet(struct lswitch *, const struct ofpbuf *);
 103 static enum ofperr process_switch_features(struct lswitch *,
 104                                            struct ofp_header *);
 105 static void process_packet_in(struct lswitch *, const struct ofp_header *);
 106 static void process_echo_request(struct lswitch *, const struct ofp_header *);
 107
 108 /* Creates and returns a new learning switch whose configuration is given by
 109  * 'cfg'.
 110  *
 111  * 'rconn' is used to send out an OpenFlow features request. */
 112 struct lswitch *
 113 lswitch_create(struct rconn *rconn, const struct lswitch_config *cfg)
 114 {
 115     struct lswitch *sw;
 116     uint32_t ofpfw;
 117
 118     sw = xzalloc(sizeof *sw);
 119     sw->rconn = rconn;
 120     sw->state = S_CONNECTING;
 121     sw->max_idle = cfg->max_idle;
 122     sw->datapath_id = 0;
 123     sw->ml = (cfg->mode == LSW_LEARN
 124               ? mac_learning_create(MAC_ENTRY_DEFAULT_IDLE_TIME)
 125               : NULL);
 126     sw->action_normal = cfg->mode == LSW_NORMAL;
 127
 128     switch (cfg->wildcards) {
 129     case 0:
 130         ofpfw = 0;
 131         break;
 132
 133     case UINT32_MAX:
 134         /* Try to wildcard as many fields as possible, but we cannot
 135          * wildcard all fields.  We need in_port to detect moves.  We need
 136          * Ethernet source and dest and VLAN VID to do L2 learning. */
 137         ofpfw = (OFPFW10_DL_TYPE | OFPFW10_DL_VLAN_PCP
 138                  | OFPFW10_NW_SRC_ALL | OFPFW10_NW_DST_ALL
 139                  | OFPFW10_NW_TOS | OFPFW10_NW_PROTO
 140                  | OFPFW10_TP_SRC | OFPFW10_TP_DST);
 141         break;
 142
 143     default:
 144         ofpfw = cfg->wildcards;
 145         break;
 146     }
 147     ofputil_wildcard_from_ofpfw10(ofpfw, &sw->wc);
 148
 149     sw->default_queue = cfg->default_queue;
 150     hmap_init(&sw->queue_numbers);
 151     shash_init(&sw->queue_names);
 152     if (cfg->port_queues) {
 153         struct simap_node *node;
 154
 155         SIMAP_FOR_EACH (node, cfg->port_queues) {
 156             struct lswitch_port *port = xmalloc(sizeof *port);
 157             hmap_node_nullify(&port->hmap_node);
 158             port->queue_id = node->data;
 159             shash_add(&sw->queue_names, node->name, port);
 160         }
 161     }
 162
 163     sw->default_flows = cfg->default_flows;
 164     sw->n_default_flows = cfg->n_default_flows;
 165     sw->usable_protocols = cfg->usable_protocols;
 166
 167     sw->queued = rconn_packet_counter_create();
 168
 169     return sw;
 170 }
 171
 172 static void
 173 lswitch_handshake(struct lswitch *sw)
 174 {
 175     enum ofputil_protocol protocol;
 176
 177     send_features_request(sw);
 178
 179     protocol = ofputil_protocol_from_ofp_version(rconn_get_version(sw->rconn));
 180     if (sw->default_flows) {
 181         struct ofpbuf *msg = NULL;
 182         int error = 0;
 183         size_t i;
 184
 185         /* If the initial protocol isn't good enough for default_flows, then
 186          * pick one that will work and encode messages to set up that
 187          * protocol.
 188          *
 189          * This could be improved by actually negotiating a mutually acceptable
 190          * flow format with the switch, but that would require an asynchronous
 191          * state machine.  This version ought to work fine in practice. */
 192         if (!(protocol & sw->usable_protocols)) {
 193             enum ofputil_protocol want = rightmost_1bit(sw->usable_protocols);
 194             while (!error) {
 195                 msg = ofputil_encode_set_protocol(protocol, want, &protocol);
 196                 if (!msg) {
 197                     break;
 198                 }
 199                 error = rconn_send(sw->rconn, msg, NULL);
 200             }
 201         }
 202         if (protocol & sw->usable_protocols) {
 203             for (i = 0; !error && i < sw->n_default_flows; i++) {
 204                 msg = ofputil_encode_flow_mod(&sw->default_flows[i], protocol);
 205                 error = rconn_send(sw->rconn, msg, NULL);
 206             }
 207
 208             if (error) {
 209                 VLOG_INFO_RL(&rl, "%s: failed to queue default flows (%s)",
 210                              rconn_get_name(sw->rconn), ovs_strerror(error));
 211             }
 212         } else {
 213             VLOG_INFO_RL(&rl, "%s: failed to set usable protocol",
 214                          rconn_get_name(sw->rconn));
 215         }
 216     }
 217     sw->protocol = protocol;
 218 }
 219
 220 bool
 221 lswitch_is_alive(const struct lswitch *sw)
 222 {
 223     return rconn_is_alive(sw->rconn);
 224 }
 225
 226 /* Destroys 'sw'. */
 227 void
 228 lswitch_destroy(struct lswitch *sw)
 229 {
 230     if (sw) {
 231         struct lswitch_port *node, *next;
 232
 233         rconn_destroy(sw->rconn);
 234         HMAP_FOR_EACH_SAFE (node, next, hmap_node, &sw->queue_numbers) {
 235             hmap_remove(&sw->queue_numbers, &node->hmap_node);
 236             free(node);
 237         }
 238         shash_destroy(&sw->queue_names);
 239         mac_learning_unref(sw->ml);
 240         rconn_packet_counter_destroy(sw->queued);
 241         free(sw);
 242     }
 243 }
 244
 245 /* Takes care of necessary 'sw' activity, except for receiving packets (which
 246  * the caller must do). */
 247 void
 248 lswitch_run(struct lswitch *sw)
 249 {
 250     int i;
 251
 252     if (sw->ml) {
 253         ovs_rwlock_wrlock(&sw->ml->rwlock);
 254         mac_learning_run(sw->ml);
 255         ovs_rwlock_unlock(&sw->ml->rwlock);
 256     }
 257
 258     rconn_run(sw->rconn);
 259
 260     if (sw->state == S_CONNECTING) {
 261         if (rconn_get_version(sw->rconn) != -1) {
 262             lswitch_handshake(sw);
 263             sw->state = S_FEATURES_REPLY;
 264         }
 265         return;
 266     }
 267
 268     for (i = 0; i < 50; i++) {
 269         struct ofpbuf *msg;
 270
 271         msg = rconn_recv(sw->rconn);
 272         if (!msg) {
 273             break;
 274         }
 275
 276         if (!sw->mute) {
 277             lswitch_process_packet(sw, msg);
 278         }
 279         ofpbuf_delete(msg);
 280     }
 281 }
 282
 283 void
 284 lswitch_wait(struct lswitch *sw)
 285 {
 286     if (sw->ml) {
 287         ovs_rwlock_rdlock(&sw->ml->rwlock);
 288         mac_learning_wait(sw->ml);
 289         ovs_rwlock_unlock(&sw->ml->rwlock);
 290     }
 291     rconn_run_wait(sw->rconn);
 292     rconn_recv_wait(sw->rconn);
 293 }
 294
 295 /* Processes 'msg', which should be an OpenFlow received on 'rconn', according
 296  * to the learning switch state in 'sw'.  The most likely result of processing
 297  * is that flow-setup and packet-out OpenFlow messages will be sent out on
 298  * 'rconn'.  */
 299 static void
 300 lswitch_process_packet(struct lswitch *sw, const struct ofpbuf *msg)
 301 {
 302     enum ofptype type;
 303     struct ofpbuf b;
 304
 305     b = *msg;
 306     if (ofptype_pull(&type, &b)) {
 307         return;
 308     }
 309
 310     if (sw->state == S_FEATURES_REPLY
 311         && type != OFPTYPE_ECHO_REQUEST
 312         && type != OFPTYPE_FEATURES_REPLY) {
 313         return;
 314     }
 315
 316     switch (type) {
 317     case OFPTYPE_ECHO_REQUEST:
 318         process_echo_request(sw, msg->data);
 319         break;
 320
 321     case OFPTYPE_FEATURES_REPLY:
 322         if (sw->state == S_FEATURES_REPLY) {
 323             if (!process_switch_features(sw, msg->data)) {
 324                 sw->state = S_SWITCHING;
 325             } else {
 326                 rconn_disconnect(sw->rconn);
 327             }
 328         }
 329         break;
 330
 331     case OFPTYPE_PACKET_IN:
 332         process_packet_in(sw, msg->data);
 333         break;
 334
 335     case OFPTYPE_FLOW_REMOVED:
 336         /* Nothing to do. */
 337         break;
 338
 339     case OFPTYPE_HELLO:
 340     case OFPTYPE_ERROR:
 341     case OFPTYPE_ECHO_REPLY:
 342     case OFPTYPE_FEATURES_REQUEST:
 343     case OFPTYPE_GET_CONFIG_REQUEST:
 344     case OFPTYPE_GET_CONFIG_REPLY:
 345     case OFPTYPE_SET_CONFIG:
 346     case OFPTYPE_PORT_STATUS:
 347     case OFPTYPE_PACKET_OUT:
 348     case OFPTYPE_FLOW_MOD:
 349     case OFPTYPE_GROUP_MOD:
 350     case OFPTYPE_PORT_MOD:
 351     case OFPTYPE_TABLE_MOD:
 352     case OFPTYPE_BARRIER_REQUEST:
 353     case OFPTYPE_BARRIER_REPLY:
 354     case OFPTYPE_QUEUE_GET_CONFIG_REQUEST:
 355     case OFPTYPE_QUEUE_GET_CONFIG_REPLY:
 356     case OFPTYPE_DESC_STATS_REQUEST:
 357     case OFPTYPE_DESC_STATS_REPLY:
 358     case OFPTYPE_FLOW_STATS_REQUEST:
 359     case OFPTYPE_FLOW_STATS_REPLY:
 360     case OFPTYPE_AGGREGATE_STATS_REQUEST:
 361     case OFPTYPE_AGGREGATE_STATS_REPLY:
 362     case OFPTYPE_TABLE_STATS_REQUEST:
 363     case OFPTYPE_TABLE_STATS_REPLY:
 364     case OFPTYPE_PORT_STATS_REQUEST:
 365     case OFPTYPE_PORT_STATS_REPLY:
 366     case OFPTYPE_QUEUE_STATS_REQUEST:
 367     case OFPTYPE_QUEUE_STATS_REPLY:
 368     case OFPTYPE_PORT_DESC_STATS_REQUEST:
 369     case OFPTYPE_PORT_DESC_STATS_REPLY:
 370     case OFPTYPE_ROLE_REQUEST:
 371     case OFPTYPE_ROLE_REPLY:
 372     case OFPTYPE_ROLE_STATUS:
 373     case OFPTYPE_SET_FLOW_FORMAT:
 374     case OFPTYPE_FLOW_MOD_TABLE_ID:
 375     case OFPTYPE_SET_PACKET_IN_FORMAT:
 376     case OFPTYPE_FLOW_AGE:
 377     case OFPTYPE_SET_CONTROLLER_ID:
 378     case OFPTYPE_FLOW_MONITOR_STATS_REQUEST:
 379     case OFPTYPE_FLOW_MONITOR_STATS_REPLY:
 380     case OFPTYPE_FLOW_MONITOR_CANCEL:
 381     case OFPTYPE_FLOW_MONITOR_PAUSED:
 382     case OFPTYPE_FLOW_MONITOR_RESUMED:
 383     case OFPTYPE_GET_ASYNC_REQUEST:
 384     case OFPTYPE_GET_ASYNC_REPLY:
 385     case OFPTYPE_SET_ASYNC_CONFIG:
 386     case OFPTYPE_METER_MOD:
 387     case OFPTYPE_GROUP_STATS_REQUEST:
 388     case OFPTYPE_GROUP_STATS_REPLY:
 389     case OFPTYPE_GROUP_DESC_STATS_REQUEST:
 390     case OFPTYPE_GROUP_DESC_STATS_REPLY:
 391     case OFPTYPE_GROUP_FEATURES_STATS_REQUEST:
 392     case OFPTYPE_GROUP_FEATURES_STATS_REPLY:
 393     case OFPTYPE_METER_STATS_REQUEST:
 394     case OFPTYPE_METER_STATS_REPLY:
 395     case OFPTYPE_METER_CONFIG_STATS_REQUEST:
 396     case OFPTYPE_METER_CONFIG_STATS_REPLY:
 397     case OFPTYPE_METER_FEATURES_STATS_REQUEST:
 398     case OFPTYPE_METER_FEATURES_STATS_REPLY:
 399     case OFPTYPE_TABLE_FEATURES_STATS_REQUEST:
 400     case OFPTYPE_TABLE_FEATURES_STATS_REPLY:
 401     default:
 402         if (VLOG_IS_DBG_ENABLED()) {
 403             char *s = ofp_to_string(msg->data, msg->size, 2);
 404             VLOG_DBG_RL(&rl, "%016llx: OpenFlow packet ignored: %s",
 405                         sw->datapath_id, s);
 406             free(s);
 407         }
 408     }
 409 }
 410 \f
 411 static void
 412 send_features_request(struct lswitch *sw)
 413 {
 414     struct ofpbuf *b;
 415     struct ofp_switch_config *osc;
 416     int ofp_version = rconn_get_version(sw->rconn);
 417
 418     ovs_assert(ofp_version > 0 && ofp_version < 0xff);
 419
 420     /* Send OFPT_FEATURES_REQUEST. */
 421     b = ofpraw_alloc(OFPRAW_OFPT_FEATURES_REQUEST, ofp_version, 0);
 422     queue_tx(sw, b);
 423
 424     /* Send OFPT_SET_CONFIG. */
 425     b = ofpraw_alloc(OFPRAW_OFPT_SET_CONFIG, ofp_version, sizeof *osc);
 426     osc = ofpbuf_put_zeros(b, sizeof *osc);
 427     osc->miss_send_len = htons(OFP_DEFAULT_MISS_SEND_LEN);
 428     queue_tx(sw, b);
 429 }
 430
 431 static void
 432 queue_tx(struct lswitch *sw, struct ofpbuf *b)
 433 {
 434     int retval = rconn_send_with_limit(sw->rconn, b, sw->queued, 10);
 435     if (retval && retval != ENOTCONN) {
 436         if (retval == EAGAIN) {
 437             VLOG_INFO_RL(&rl, "%016llx: %s: tx queue overflow",
 438                          sw->datapath_id, rconn_get_name(sw->rconn));
 439         } else {
 440             VLOG_WARN_RL(&rl, "%016llx: %s: send: %s",
 441                          sw->datapath_id, rconn_get_name(sw->rconn),
 442                          ovs_strerror(retval));
 443         }
 444     }
 445 }
 446
 447 static enum ofperr
 448 process_switch_features(struct lswitch *sw, struct ofp_header *oh)
 449 {
 450     struct ofputil_switch_features features;
 451     struct ofputil_phy_port port;
 452     enum ofperr error;
 453     struct ofpbuf b;
 454
 455     error = ofputil_decode_switch_features(oh, &features, &b);
 456     if (error) {
 457         VLOG_ERR("received invalid switch feature reply (%s)",
 458                  ofperr_to_string(error));
 459         return error;
 460     }
 461
 462     sw->datapath_id = features.datapath_id;
 463
 464     while (!ofputil_pull_phy_port(oh->version, &b, &port)) {
 465         struct lswitch_port *lp = shash_find_data(&sw->queue_names, port.name);
 466         if (lp && hmap_node_is_null(&lp->hmap_node)) {
 467             lp->port_no = port.port_no;
 468             hmap_insert(&sw->queue_numbers, &lp->hmap_node,
 469                         hash_ofp_port(lp->port_no));
 470         }
 471     }
 472     return 0;
 473 }
 474
 475 static ofp_port_t
 476 lswitch_choose_destination(struct lswitch *sw, const struct flow *flow)
 477 {
 478     ofp_port_t out_port;
 479
 480     /* Learn the source MAC. */
 481     if (sw->ml) {
 482         ovs_rwlock_wrlock(&sw->ml->rwlock);
 483         if (mac_learning_may_learn(sw->ml, flow->dl_src, 0)) {
 484             struct mac_entry *mac = mac_learning_insert(sw->ml, flow->dl_src,
 485                                                         0);
 486             if (mac->port.ofp_port != flow->in_port.ofp_port) {
 487                 VLOG_DBG_RL(&rl, "%016llx: learned that "ETH_ADDR_FMT" is on "
 488                             "port %"PRIu16, sw->datapath_id,
 489                             ETH_ADDR_ARGS(flow->dl_src),
 490                             flow->in_port.ofp_port);
 491
 492                 mac->port.ofp_port = flow->in_port.ofp_port;
 493                 mac_learning_changed(sw->ml);
 494             }
 495         }
 496         ovs_rwlock_unlock(&sw->ml->rwlock);
 497     }
 498
 499     /* Drop frames for reserved multicast addresses. */
 500     if (eth_addr_is_reserved(flow->dl_dst)) {
 501         return OFPP_NONE;
 502     }
 503
 504     out_port = OFPP_FLOOD;
 505     if (sw->ml) {
 506         struct mac_entry *mac;
 507
 508         ovs_rwlock_rdlock(&sw->ml->rwlock);
 509         mac = mac_learning_lookup(sw->ml, flow->dl_dst, 0);
 510         if (mac) {
 511             out_port = mac->port.ofp_port;
 512             if (out_port == flow->in_port.ofp_port) {
 513                 /* Don't send a packet back out its input port. */
 514                 ovs_rwlock_unlock(&sw->ml->rwlock);
 515                 return OFPP_NONE;
 516             }
 517         }
 518         ovs_rwlock_unlock(&sw->ml->rwlock);
 519     }
 520
 521     /* Check if we need to use "NORMAL" action. */
 522     if (sw->action_normal && out_port != OFPP_FLOOD) {
 523         return OFPP_NORMAL;
 524     }
 525
 526     return out_port;
 527 }
 528
 529 static uint32_t
 530 get_queue_id(const struct lswitch *sw, ofp_port_t in_port)
 531 {
 532     const struct lswitch_port *port;
 533
 534     HMAP_FOR_EACH_WITH_HASH (port, hmap_node, hash_ofp_port(in_port),
 535                              &sw->queue_numbers) {
 536         if (port->port_no == in_port) {
 537             return port->queue_id;
 538         }
 539     }
 540
 541     return sw->default_queue;
 542 }
 543
 544 static void
 545 process_packet_in(struct lswitch *sw, const struct ofp_header *oh)
 546 {
 547     struct ofputil_packet_in pi;
 548     uint32_t queue_id;
 549     ofp_port_t out_port;
 550
 551     uint64_t ofpacts_stub[64 / 8];
 552     struct ofpbuf ofpacts;
 553
 554     struct ofputil_packet_out po;
 555     enum ofperr error;
 556
 557     struct ofpbuf pkt;
 558     struct flow flow;
 559     union flow_in_port in_port_;
 560
 561     error = ofputil_decode_packet_in(&pi, oh);
 562     if (error) {
 563         VLOG_WARN_RL(&rl, "failed to decode packet-in: %s",
 564                      ofperr_to_string(error));
 565         return;
 566     }
 567
 568     /* Ignore packets sent via output to OFPP_CONTROLLER.  This library never
 569      * uses such an action.  You never know what experiments might be going on,
 570      * though, and it seems best not to interfere with them. */
 571     if (pi.reason != OFPR_NO_MATCH) {
 572         return;
 573     }
 574
 575     /* Extract flow data from 'opi' into 'flow'. */
 576     ofpbuf_use_const(&pkt, pi.packet, pi.packet_len);
 577     in_port_.ofp_port = pi.fmd.in_port;
 578     flow_extract(&pkt, 0, 0, NULL, &in_port_, &flow);
 579     flow.tunnel.tun_id = pi.fmd.tun_id;
 580
 581     /* Choose output port. */
 582     out_port = lswitch_choose_destination(sw, &flow);
 583
 584     /* Make actions. */
 585     queue_id = get_queue_id(sw, pi.fmd.in_port);
 586     ofpbuf_use_stack(&ofpacts, ofpacts_stub, sizeof ofpacts_stub);
 587     if (out_port == OFPP_NONE) {
 588         /* No actions. */
 589     } else if (queue_id == UINT32_MAX
 590                || ofp_to_u16(out_port) >= ofp_to_u16(OFPP_MAX)) {
 591         ofpact_put_OUTPUT(&ofpacts)->port = out_port;
 592     } else {
 593         struct ofpact_enqueue *enqueue = ofpact_put_ENQUEUE(&ofpacts);
 594         enqueue->port = out_port;
 595         enqueue->queue = queue_id;
 596     }
 597     ofpact_pad(&ofpacts);
 598
 599     /* Prepare packet_out in case we need one. */
 600     po.buffer_id = pi.buffer_id;
 601     if (po.buffer_id == UINT32_MAX) {
 602         po.packet = pkt.data;
 603         po.packet_len = pkt.size;
 604     } else {
 605         po.packet = NULL;
 606         po.packet_len = 0;
 607     }
 608     po.in_port = pi.fmd.in_port;
 609     po.ofpacts = ofpacts.data;
 610     po.ofpacts_len = ofpacts.size;
 611
 612     /* Send the packet, and possibly the whole flow, to the output port. */
 613     if (sw->max_idle >= 0 && (!sw->ml || out_port != OFPP_FLOOD)) {
 614         struct ofputil_flow_mod fm;
 615         struct ofpbuf *buffer;
 616
 617         /* The output port is known, or we always flood everything, so add a
 618          * new flow. */
 619         memset(&fm, 0, sizeof fm);
 620         match_init(&fm.match, &flow, &sw->wc);
 621         ofputil_normalize_match_quiet(&fm.match);
 622         fm.priority = 0;
 623         fm.table_id = 0xff;
 624         fm.command = OFPFC_ADD;
 625         fm.idle_timeout = sw->max_idle;
 626         fm.buffer_id = pi.buffer_id;
 627         fm.out_port = OFPP_NONE;
 628         fm.ofpacts = ofpacts.data;
 629         fm.ofpacts_len = ofpacts.size;
 630         buffer = ofputil_encode_flow_mod(&fm, sw->protocol);
 631
 632         queue_tx(sw, buffer);
 633
 634         /* If the switch didn't buffer the packet, we need to send a copy. */
 635         if (pi.buffer_id == UINT32_MAX && out_port != OFPP_NONE) {
 636             queue_tx(sw, ofputil_encode_packet_out(&po, sw->protocol));
 637         }
 638     } else {
 639         /* We don't know that MAC, or we don't set up flows.  Send along the
 640          * packet without setting up a flow. */
 641         if (pi.buffer_id != UINT32_MAX || out_port != OFPP_NONE) {
 642             queue_tx(sw, ofputil_encode_packet_out(&po, sw->protocol));
 643         }
 644     }
 645 }
 646
 647 static void
 648 process_echo_request(struct lswitch *sw, const struct ofp_header *rq)
 649 {
 650     queue_tx(sw, make_echo_reply(rq));
 651 }