ofproto/fail-open.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 "fail-open.h"
  19 #include <inttypes.h>
  20 #include <stdlib.h>
  21 #include "flow.h"
  22 #include "mac-learning.h"
  23 #include "odp-util.h"
  24 #include "ofp-util.h"
  25 #include "ofpbuf.h"
  26 #include "ofproto.h"
  27 #include "pktbuf.h"
  28 #include "poll-loop.h"
  29 #include "rconn.h"
  30 #include "status.h"
  31 #include "timeval.h"
  32 #include "vconn.h"
  33 #include "vlog.h"
  34
  35 VLOG_DEFINE_THIS_MODULE(fail_open)
  36
  37 /*
  38  * Fail-open mode.
  39  *
  40  * In fail-open mode, the switch detects when the controller cannot be
  41  * contacted or when the controller is dropping switch connections because the
  42  * switch does not pass its admission control policy.  In those situations the
  43  * switch sets up flows itself using the "normal" action.
  44  *
  45  * There is a little subtlety to implementation, to properly handle the case
  46  * where the controller allows switch connections but drops them a few seconds
  47  * later for admission control reasons.  Because of this case, we don't want to
  48  * just stop setting up flows when we connect to the controller: if we did,
  49  * then new flow setup and existing flows would stop during the duration of
  50  * connection to the controller, and thus the whole network would go down for
  51  * that period of time.
  52  *
  53  * So, instead, we add some special cases when we are connected to a
  54  * controller, but not yet sure that it has admitted us:
  55  *
  56  *     - We set up flows immediately ourselves, but simultaneously send out an
  57  *       OFPT_PACKET_IN to the controller.  We put a special bogus buffer-id in
  58  *       these OFPT_PACKET_IN messages so that duplicate packets don't get sent
  59  *       out to the network when the controller replies.
  60  *
  61  *     - We also send out OFPT_PACKET_IN messages for totally bogus packets
  62  *       every so often, in case no real new flows are arriving in the network.
  63  *
  64  *     - We don't flush the flow table at the time we connect, because this
  65  *       could cause network stuttering in a switch with lots of flows or very
  66  *       high-bandwidth flows by suddenly throwing lots of packets down to
  67  *       userspace.
  68  */
  69
  70 struct fail_open {
  71     struct ofproto *ofproto;
  72     struct rconn **controllers;
  73     size_t n_controllers;
  74     int last_disconn_secs;
  75     struct status_category *ss_cat;
  76     long long int next_bogus_packet_in;
  77     struct rconn_packet_counter *bogus_packet_counter;
  78 };
  79
  80 static void fail_open_recover(struct fail_open *);
  81
  82 /* Returns the number of seconds of disconnection after which fail-open mode
  83  * should activate. */
  84 static int
  85 trigger_duration(const struct fail_open *fo)
  86 {
  87     if (!fo->n_controllers) {
  88         /* Shouldn't ever arrive here, but if we do, never fail open. */
  89         return INT_MAX;
  90     } else {
  91         /* Otherwise, every controller must have a chance to send an
  92          * inactivity probe and reconnect before we fail open, so take the
  93          * maximum probe interval and multiply by 3:
  94          *
  95          *  - The first interval is the idle time before sending an inactivity
  96          *    probe.
  97          *
  98          *  - The second interval is the time allowed for a response to the
  99          *    inactivity probe.
 100          *
 101          *  - The third interval is the time allowed to reconnect after no
 102          *    response is received.
 103          */
 104         int max_probe_interval;
 105         size_t i;
 106
 107         max_probe_interval = 0;
 108         for (i = 0; i < fo->n_controllers; i++) {
 109             int probe_interval = rconn_get_probe_interval(fo->controllers[i]);
 110             max_probe_interval = MAX(max_probe_interval, probe_interval);
 111         }
 112         return max_probe_interval * 3;
 113     }
 114 }
 115
 116 /* Returns the number of seconds for which all controllers have been
 117  * disconnected.  */
 118 static int
 119 failure_duration(const struct fail_open *fo)
 120 {
 121     int min_failure_duration;
 122     size_t i;
 123
 124     if (!fo->n_controllers) {
 125         return 0;
 126     }
 127
 128     min_failure_duration = INT_MAX;
 129     for (i = 0; i < fo->n_controllers; i++) {
 130         int failure_duration = rconn_failure_duration(fo->controllers[i]);
 131         min_failure_duration = MIN(min_failure_duration, failure_duration);
 132     }
 133     return min_failure_duration;
 134 }
 135
 136 /* Returns true if 'fo' is currently in fail-open mode, otherwise false. */
 137 bool
 138 fail_open_is_active(const struct fail_open *fo)
 139 {
 140     return fo->last_disconn_secs != 0;
 141 }
 142
 143 /* Returns true if at least one controller is connected (regardless of whether
 144  * those controllers are believed to have authenticated and accepted this
 145  * switch), false if none of them are connected. */
 146 static bool
 147 any_controller_is_connected(const struct fail_open *fo)
 148 {
 149     size_t i;
 150
 151     for (i = 0; i < fo->n_controllers; i++) {
 152         if (rconn_is_connected(fo->controllers[i])) {
 153             return true;
 154         }
 155     }
 156     return false;
 157 }
 158
 159 /* Returns true if at least one controller is believed to have authenticated
 160  * and accepted this switch, false otherwise. */
 161 static bool
 162 any_controller_is_admitted(const struct fail_open *fo)
 163 {
 164     size_t i;
 165
 166     for (i = 0; i < fo->n_controllers; i++) {
 167         if (rconn_is_admitted(fo->controllers[i])) {
 168             return true;
 169         }
 170     }
 171     return false;
 172 }
 173
 174 static void
 175 send_bogus_packet_in(struct fail_open *fo, struct rconn *rconn)
 176 {
 177     uint8_t mac[ETH_ADDR_LEN];
 178     struct ofpbuf *opi;
 179     struct ofpbuf b;
 180
 181     /* Compose ofp_packet_in. */
 182     ofpbuf_init(&b, 128);
 183     eth_addr_nicira_random(mac);
 184     compose_benign_packet(&b, "Open vSwitch Controller Probe", 0xa033, mac);
 185     opi = make_packet_in(pktbuf_get_null(), OFPP_LOCAL, OFPR_NO_MATCH, &b, 64);
 186     ofpbuf_uninit(&b);
 187
 188     /* Send. */
 189     rconn_send_with_limit(rconn, opi, fo->bogus_packet_counter, 1);
 190 }
 191
 192 static void
 193 send_bogus_packet_ins(struct fail_open *fo)
 194 {
 195     size_t i;
 196
 197     for (i = 0; i < fo->n_controllers; i++) {
 198         if (rconn_is_connected(fo->controllers[i])) {
 199             send_bogus_packet_in(fo, fo->controllers[i]);
 200         }
 201     }
 202 }
 203
 204 /* Enter fail-open mode if we should be in it. */
 205 void
 206 fail_open_run(struct fail_open *fo)
 207 {
 208     int disconn_secs = failure_duration(fo);
 209
 210     /* Enter fail-open mode if 'fo' is not in it but should be.  */
 211     if (disconn_secs >= trigger_duration(fo)) {
 212         if (!fail_open_is_active(fo)) {
 213             VLOG_WARN("Could not connect to controller (or switch failed "
 214                       "controller's post-connection admission control "
 215                       "policy) for %d seconds, failing open", disconn_secs);
 216             fo->last_disconn_secs = disconn_secs;
 217
 218             /* Flush all OpenFlow and datapath flows.  We will set up our
 219              * fail-open rule from fail_open_flushed() when
 220              * ofproto_flush_flows() calls back to us. */
 221             ofproto_flush_flows(fo->ofproto);
 222         } else if (disconn_secs > fo->last_disconn_secs + 60) {
 223             VLOG_INFO("Still in fail-open mode after %d seconds disconnected "
 224                       "from controller", disconn_secs);
 225             fo->last_disconn_secs = disconn_secs;
 226         }
 227     }
 228
 229     /* Schedule a bogus packet-in if we're connected and in fail-open. */
 230     if (fail_open_is_active(fo)) {
 231         if (any_controller_is_connected(fo)) {
 232             bool expired = time_msec() >= fo->next_bogus_packet_in;
 233             if (expired) {
 234                 send_bogus_packet_ins(fo);
 235             }
 236             if (expired || fo->next_bogus_packet_in == LLONG_MAX) {
 237                 fo->next_bogus_packet_in = time_msec() + 2000;
 238             }
 239         } else {
 240             fo->next_bogus_packet_in = LLONG_MAX;
 241         }
 242     }
 243
 244 }
 245
 246 /* If 'fo' is currently in fail-open mode and its rconn has connected to the
 247  * controller, exits fail open mode. */
 248 void
 249 fail_open_maybe_recover(struct fail_open *fo)
 250 {
 251     if (any_controller_is_admitted(fo)) {
 252         fail_open_recover(fo);
 253     }
 254 }
 255
 256 static void
 257 fail_open_recover(struct fail_open *fo)
 258 {
 259     if (fail_open_is_active(fo)) {
 260         struct flow flow;
 261
 262         VLOG_WARN("No longer in fail-open mode");
 263         fo->last_disconn_secs = 0;
 264         fo->next_bogus_packet_in = LLONG_MAX;
 265
 266         memset(&flow, 0, sizeof flow);
 267         ofproto_delete_flow(fo->ofproto, &flow, OVSFW_ALL, FAIL_OPEN_PRIORITY);
 268     }
 269 }
 270
 271 void
 272 fail_open_wait(struct fail_open *fo)
 273 {
 274     if (fo->next_bogus_packet_in != LLONG_MAX) {
 275         poll_timer_wait_until(fo->next_bogus_packet_in);
 276     }
 277 }
 278
 279 void
 280 fail_open_flushed(struct fail_open *fo)
 281 {
 282     int disconn_secs = failure_duration(fo);
 283     bool open = disconn_secs >= trigger_duration(fo);
 284     if (open) {
 285         union ofp_action action;
 286         struct flow flow;
 287
 288         /* Set up a flow that matches every packet and directs them to
 289          * OFPP_NORMAL. */
 290         memset(&action, 0, sizeof action);
 291         action.type = htons(OFPAT_OUTPUT);
 292         action.output.len = htons(sizeof action);
 293         action.output.port = htons(OFPP_NORMAL);
 294         memset(&flow, 0, sizeof flow);
 295         ofproto_add_flow(fo->ofproto, &flow, OVSFW_ALL, FAIL_OPEN_PRIORITY,
 296                          &action, 1, 0);
 297     }
 298 }
 299
 300 static void
 301 fail_open_status_cb(struct status_reply *sr, void *fo_)
 302 {
 303     struct fail_open *fo = fo_;
 304     int cur_duration = failure_duration(fo);
 305     int trigger = trigger_duration(fo);
 306
 307     status_reply_put(sr, "trigger-duration=%d", trigger);
 308     status_reply_put(sr, "current-duration=%d", cur_duration);
 309     status_reply_put(sr, "triggered=%s",
 310                      cur_duration >= trigger ? "true" : "false");
 311 }
 312
 313 /* Creates and returns a new struct fail_open for 'ofproto', registering switch
 314  * status with 'switch_status'.
 315  *
 316  * The caller should register its set of controllers with
 317  * fail_open_set_controllers().  (There should be at least one controller,
 318  * otherwise there isn't any point in having the struct fail_open around.) */
 319 struct fail_open *
 320 fail_open_create(struct ofproto *ofproto, struct switch_status *switch_status)
 321 {
 322     struct fail_open *fo = xmalloc(sizeof *fo);
 323     fo->ofproto = ofproto;
 324     fo->controllers = NULL;
 325     fo->n_controllers = 0;
 326     fo->last_disconn_secs = 0;
 327     fo->ss_cat = switch_status_register(switch_status, "fail-open",
 328                                         fail_open_status_cb, fo);
 329     fo->next_bogus_packet_in = LLONG_MAX;
 330     fo->bogus_packet_counter = rconn_packet_counter_create();
 331     return fo;
 332 }
 333
 334 /* Registers the 'n' rconns in 'rconns' as connections to the controller for
 335  * 'fo'.  The caller must ensure that all of the rconns remain valid until 'fo'
 336  * is destroyed or a new set is registered in a subsequent call.
 337  *
 338  * Takes ownership of the 'rconns' array, but not of the rconns that it points
 339  * to (of which the caller retains ownership). */
 340 void
 341 fail_open_set_controllers(struct fail_open *fo,
 342                           struct rconn **rconns, size_t n)
 343 {
 344     free(fo->controllers);
 345     fo->controllers = rconns;
 346     fo->n_controllers = n;
 347 }
 348
 349 /* Destroys 'fo'. */
 350 void
 351 fail_open_destroy(struct fail_open *fo)
 352 {
 353     if (fo) {
 354         fail_open_recover(fo);
 355         free(fo->controllers);
 356         /* We don't own the rconns behind fo->controllers. */
 357         switch_status_unregister(fo->ss_cat);
 358         rconn_packet_counter_destroy(fo->bogus_packet_counter);
 359         free(fo);
 360     }
 361 }