ofproto/fail-open.c

   1 /*
   2  * Copyright (c) 2008, 2009 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 "ofpbuf.h"
  25 #include "ofproto.h"
  26 #include "pktbuf.h"
  27 #include "poll-loop.h"
  28 #include "rconn.h"
  29 #include "status.h"
  30 #include "timeval.h"
  31 #include "vconn.h"
  32
  33 #define THIS_MODULE VLM_fail_open
  34 #include "vlog.h"
  35
  36 /*
  37  * Fail-open mode.
  38  *
  39  * In fail-open mode, the switch detects when the controller cannot be
  40  * contacted or when the controller is dropping switch connections because the
  41  * switch does not pass its admission control policy.  In those situations the
  42  * switch sets up flows itself using the "normal" action.
  43  *
  44  * There is a little subtlety to implementation, to properly handle the case
  45  * where the controller allows switch connections but drops them a few seconds
  46  * later for admission control reasons.  Because of this case, we don't want to
  47  * just stop setting up flows when we connect to the controller: if we did,
  48  * then new flow setup and existing flows would stop during the duration of
  49  * connection to the controller, and thus the whole network would go down for
  50  * that period of time.
  51  *
  52  * So, instead, we add some special caseswhen we are connected to a controller,
  53  * but not yet sure that it has admitted us:
  54  *
  55  *     - We set up flows immediately ourselves, but simultaneously send out an
  56  *       OFPT_PACKET_IN to the controller.  We put a special bogus buffer-id in
  57  *       these OFPT_PACKET_IN messages so that duplicate packets don't get sent
  58  *       out to the network when the controller replies.
  59  *
  60  *     - We also send out OFPT_PACKET_IN messages for totally bogus packets
  61  *       every so often, in case no real new flows are arriving in the network.
  62  *
  63  *     - We don't flush the flow table at the time we connect, because this
  64  *       could cause network stuttering in a switch with lots of flows or very
  65  *       high-bandwidth flows by suddenly throwing lots of packets down to
  66  *       userspace.
  67  */
  68
  69 struct fail_open {
  70     struct ofproto *ofproto;
  71     struct rconn *controller;
  72     int trigger_duration;
  73     int last_disconn_secs;
  74     struct status_category *ss_cat;
  75     long long int next_bogus_packet_in;
  76     struct rconn_packet_counter *bogus_packet_counter;
  77 };
  78
  79 /* Returns true if 'fo' should be in fail-open mode, otherwise false. */
  80 static inline bool
  81 should_fail_open(const struct fail_open *fo)
  82 {
  83     return rconn_failure_duration(fo->controller) >= fo->trigger_duration;
  84 }
  85
  86 /* Returns true if 'fo' is currently in fail-open mode, otherwise false. */
  87 bool
  88 fail_open_is_active(const struct fail_open *fo)
  89 {
  90     return fo->last_disconn_secs != 0;
  91 }
  92
  93 static void
  94 send_bogus_packet_in(struct fail_open *fo)
  95 {
  96     uint8_t mac[ETH_ADDR_LEN];
  97     struct ofpbuf *opi;
  98     struct ofpbuf b;
  99
 100     /* Compose ofp_packet_in. */
 101     ofpbuf_init(&b, 128);
 102     eth_addr_random(mac);
 103     compose_benign_packet(&b, "Open vSwitch Controller Probe", 0xa033, mac);
 104     opi = make_packet_in(pktbuf_get_null(), OFPP_LOCAL, OFPR_NO_MATCH, &b, 64);
 105     ofpbuf_uninit(&b);
 106
 107     /* Send. */
 108     rconn_send_with_limit(fo->controller, opi, fo->bogus_packet_counter, 1);
 109 }
 110
 111 /* Enter fail-open mode if we should be in it.  Handle reconnecting to a
 112  * controller from fail-open mode. */
 113 void
 114 fail_open_run(struct fail_open *fo)
 115 {
 116     /* Enter fail-open mode if 'fo' is not in it but should be.  */
 117     if (should_fail_open(fo)) {
 118         int disconn_secs = rconn_failure_duration(fo->controller);
 119         if (!fail_open_is_active(fo)) {
 120             VLOG_WARN("Could not connect to controller (or switch failed "
 121                       "controller's post-connection admission control "
 122                       "policy) for %d seconds, failing open", disconn_secs);
 123             fo->last_disconn_secs = disconn_secs;
 124
 125             /* Flush all OpenFlow and datapath flows.  We will set up our
 126              * fail-open rule from fail_open_flushed() when
 127              * ofproto_flush_flows() calls back to us. */
 128             ofproto_flush_flows(fo->ofproto);
 129         } else if (disconn_secs > fo->last_disconn_secs + 60) {
 130             VLOG_INFO("Still in fail-open mode after %d seconds disconnected "
 131                       "from controller", disconn_secs);
 132             fo->last_disconn_secs = disconn_secs;
 133         }
 134     }
 135
 136     /* Schedule a bogus packet-in if we're connected and in fail-open. */
 137     if (fail_open_is_active(fo)) {
 138         if (rconn_is_connected(fo->controller)) {
 139             bool expired = time_msec() >= fo->next_bogus_packet_in;
 140             if (expired) {
 141                 send_bogus_packet_in(fo);
 142             }
 143             if (expired || fo->next_bogus_packet_in == LLONG_MAX) {
 144                 fo->next_bogus_packet_in = time_msec() + 2000;
 145             }
 146         } else {
 147             fo->next_bogus_packet_in = LLONG_MAX;
 148         }
 149     }
 150
 151 }
 152
 153 /* If 'fo' is currently in fail-open mode and its rconn has connected to the
 154  * controller, exits fail open mode. */
 155 void
 156 fail_open_maybe_recover(struct fail_open *fo)
 157 {
 158     if (fail_open_is_active(fo) && rconn_is_admitted(fo->controller)) {
 159         flow_t flow;
 160
 161         VLOG_WARN("No longer in fail-open mode");
 162         fo->last_disconn_secs = 0;
 163         fo->next_bogus_packet_in = LLONG_MAX;
 164
 165         memset(&flow, 0, sizeof flow);
 166         ofproto_delete_flow(fo->ofproto, &flow, OFPFW_ALL, FAIL_OPEN_PRIORITY);
 167     }
 168 }
 169
 170 void
 171 fail_open_wait(struct fail_open *fo)
 172 {
 173     if (fo->next_bogus_packet_in != LLONG_MAX) {
 174         poll_timer_wait(fo->next_bogus_packet_in - time_msec());
 175     }
 176 }
 177
 178 void
 179 fail_open_flushed(struct fail_open *fo)
 180 {
 181     int disconn_secs = rconn_failure_duration(fo->controller);
 182     bool open = disconn_secs >= fo->trigger_duration;
 183     if (open) {
 184         union ofp_action action;
 185         flow_t flow;
 186
 187         /* Set up a flow that matches every packet and directs them to
 188          * OFPP_NORMAL. */
 189         memset(&action, 0, sizeof action);
 190         action.type = htons(OFPAT_OUTPUT);
 191         action.output.len = htons(sizeof action);
 192         action.output.port = htons(OFPP_NORMAL);
 193         memset(&flow, 0, sizeof flow);
 194         ofproto_add_flow(fo->ofproto, &flow, OFPFW_ALL, FAIL_OPEN_PRIORITY,
 195                          &action, 1, 0);
 196     }
 197 }
 198
 199 static void
 200 fail_open_status_cb(struct status_reply *sr, void *fo_)
 201 {
 202     struct fail_open *fo = fo_;
 203     int cur_duration = rconn_failure_duration(fo->controller);
 204
 205     status_reply_put(sr, "trigger-duration=%d", fo->trigger_duration);
 206     status_reply_put(sr, "current-duration=%d", cur_duration);
 207     status_reply_put(sr, "triggered=%s",
 208                      cur_duration >= fo->trigger_duration ? "true" : "false");
 209 }
 210
 211 struct fail_open *
 212 fail_open_create(struct ofproto *ofproto,
 213                  int trigger_duration, struct switch_status *switch_status,
 214                  struct rconn *controller)
 215 {
 216     struct fail_open *fo = xmalloc(sizeof *fo);
 217     fo->ofproto = ofproto;
 218     fo->controller = controller;
 219     fo->trigger_duration = trigger_duration;
 220     fo->last_disconn_secs = 0;
 221     fo->ss_cat = switch_status_register(switch_status, "fail-open",
 222                                         fail_open_status_cb, fo);
 223     fo->next_bogus_packet_in = LLONG_MAX;
 224     fo->bogus_packet_counter = rconn_packet_counter_create();
 225     return fo;
 226 }
 227
 228 void
 229 fail_open_set_trigger_duration(struct fail_open *fo, int trigger_duration)
 230 {
 231     fo->trigger_duration = trigger_duration;
 232 }
 233
 234 void
 235 fail_open_destroy(struct fail_open *fo)
 236 {
 237     if (fo) {
 238         /* We don't own fo->controller. */
 239         switch_status_unregister(fo->ss_cat);
 240         rconn_packet_counter_destroy(fo->bogus_packet_counter);
 241         free(fo);
 242     }
 243 }