1 /* Copyright (c) 2008 The Board of Trustees of The Leland Stanford
4 * We are making the OpenFlow specification and associated documentation
5 * (Software) available for public use and benefit with the expectation
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11 * the Software under the copyrights without restriction, including
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14 * permit persons to whom the Software is furnished to do so, subject to
15 * the following conditions:
17 * The above copyright notice and this permission notice shall be
18 * included in all copies or substantial portions of the Software.
20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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24 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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42 #include "openflow/openflow.h"
43 #include "poll-loop.h"
49 #define THIS_MODULE VLM_rconn
54 STATE(BACKOFF, 1 << 1) \
55 STATE(CONNECTING, 1 << 2) \
56 STATE(ACTIVE, 1 << 3) \
59 #define STATE(NAME, VALUE) S_##NAME = VALUE,
65 state_name(enum state state)
68 #define STATE(NAME, VALUE) case S_##NAME: return #NAME;
75 /* A reliable connection to an OpenFlow switch or controller.
77 * See the large comment in rconn.h for more information. */
90 time_t backoff_deadline;
92 time_t last_connected;
93 unsigned int packets_sent;
95 /* In S_ACTIVE and S_IDLE, probably_admitted reports whether we believe
96 * that the peer has made a (positive) admission control decision on our
97 * connection. If we have not yet been (probably) admitted, then the
98 * connection does not reset the timer used for deciding whether the switch
99 * should go into fail-open mode.
101 * last_admitted reports the last time we believe such a positive admission
102 * control decision was made. */
103 bool probably_admitted;
104 time_t last_admitted;
106 /* These values are simply for statistics reporting, not used directly by
107 * anything internal to the rconn (or the secchan for that matter). */
108 unsigned int packets_received;
109 unsigned int n_attempted_connections, n_successful_connections;
110 time_t creation_time;
111 unsigned long int total_time_connected;
113 /* If we can't connect to the peer, it could be for any number of reasons.
114 * Usually, one would assume it is because the peer is not running or
115 * because the network is partitioned. But it could also be because the
116 * network topology has changed, in which case the upper layer will need to
117 * reassess it (in particular, obtain a new IP address via DHCP and find
118 * the new location of the controller). We set this flag when we suspect
119 * that this could be the case. */
120 bool questionable_connectivity;
121 time_t last_questioned;
123 /* Throughout this file, "probe" is shorthand for "inactivity probe".
124 * When nothing has been received from the peer for a while, we send out
125 * an echo request as an inactivity probe packet. We should receive back
127 int probe_interval; /* Secs of inactivity before sending probe. */
129 /* Messages sent or received are copied to the monitor connections. */
130 #define MAX_MONITORS 8
131 struct vconn *monitors[8];
135 static unsigned int elapsed_in_this_state(const struct rconn *);
136 static unsigned int timeout(const struct rconn *);
137 static bool timed_out(const struct rconn *);
138 static void state_transition(struct rconn *, enum state);
139 static int try_send(struct rconn *);
140 static int reconnect(struct rconn *);
141 static void disconnect(struct rconn *, int error);
142 static void flush_queue(struct rconn *);
143 static void question_connectivity(struct rconn *);
144 static void copy_to_monitor(struct rconn *, const struct ofpbuf *);
145 static bool is_connected_state(enum state);
146 static bool is_admitted_msg(const struct ofpbuf *);
148 /* Creates a new rconn, connects it (reliably) to 'name', and returns it. */
150 rconn_new(const char *name, int inactivity_probe_interval, int max_backoff)
152 struct rconn *rc = rconn_create(inactivity_probe_interval, max_backoff);
153 rconn_connect(rc, name);
157 /* Creates a new rconn, connects it (unreliably) to 'vconn', and returns it. */
159 rconn_new_from_vconn(const char *name, struct vconn *vconn)
161 struct rconn *rc = rconn_create(60, 0);
162 rconn_connect_unreliably(rc, name, vconn);
166 /* Creates and returns a new rconn.
168 * 'probe_interval' is a number of seconds. If the interval passes once
169 * without an OpenFlow message being received from the peer, the rconn sends
170 * out an "echo request" message. If the interval passes again without a
171 * message being received, the rconn disconnects and re-connects to the peer.
172 * Setting 'probe_interval' to 0 disables this behavior.
174 * 'max_backoff' is the maximum number of seconds between attempts to connect
175 * to the peer. The actual interval starts at 1 second and doubles on each
176 * failure until it reaches 'max_backoff'. If 0 is specified, the default of
177 * 60 seconds is used. */
179 rconn_create(int probe_interval, int max_backoff)
181 struct rconn *rc = xcalloc(1, sizeof *rc);
184 rc->state_entered = time_now();
187 rc->name = xstrdup("void");
188 rc->reliable = false;
190 queue_init(&rc->txq);
193 rc->max_backoff = max_backoff ? max_backoff : 60;
194 rc->backoff_deadline = TIME_MIN;
195 rc->last_received = time_now();
196 rc->last_connected = time_now();
198 rc->packets_sent = 0;
200 rc->probably_admitted = false;
201 rc->last_admitted = time_now();
203 rc->packets_received = 0;
204 rc->n_attempted_connections = 0;
205 rc->n_successful_connections = 0;
206 rc->creation_time = time_now();
207 rc->total_time_connected = 0;
209 rc->questionable_connectivity = false;
210 rc->last_questioned = time_now();
212 rc->probe_interval = probe_interval ? MAX(5, probe_interval) : 0;
220 rconn_connect(struct rconn *rc, const char *name)
222 rconn_disconnect(rc);
224 rc->name = xstrdup(name);
226 return reconnect(rc);
230 rconn_connect_unreliably(struct rconn *rc,
231 const char *name, struct vconn *vconn)
233 assert(vconn != NULL);
234 rconn_disconnect(rc);
236 rc->name = xstrdup(name);
237 rc->reliable = false;
239 rc->last_connected = time_now();
240 state_transition(rc, S_ACTIVE);
244 rconn_disconnect(struct rconn *rc)
246 if (rc->state != S_VOID) {
248 vconn_close(rc->vconn);
252 rc->name = xstrdup("void");
253 rc->reliable = false;
256 rc->backoff_deadline = TIME_MIN;
258 state_transition(rc, S_VOID);
262 /* Disconnects 'rc' and frees the underlying storage. */
264 rconn_destroy(struct rconn *rc)
270 vconn_close(rc->vconn);
272 queue_destroy(&rc->txq);
273 for (i = 0; i < rc->n_monitors; i++) {
274 vconn_close(rc->monitors[i]);
281 timeout_VOID(const struct rconn *rc)
287 run_VOID(struct rconn *rc)
293 reconnect(struct rconn *rc)
297 VLOG_WARN("%s: connecting...", rc->name);
298 rc->n_attempted_connections++;
299 retval = vconn_open(rc->name, OFP_VERSION, &rc->vconn);
301 rc->backoff_deadline = time_now() + rc->backoff;
302 state_transition(rc, S_CONNECTING);
304 VLOG_WARN("%s: connection failed (%s)", rc->name, strerror(retval));
305 rc->backoff_deadline = TIME_MAX; /* Prevent resetting backoff. */
312 timeout_BACKOFF(const struct rconn *rc)
318 run_BACKOFF(struct rconn *rc)
326 timeout_CONNECTING(const struct rconn *rc)
328 return MAX(1, rc->backoff);
332 run_CONNECTING(struct rconn *rc)
334 int retval = vconn_connect(rc->vconn);
336 VLOG_WARN("%s: connected", rc->name);
337 rc->n_successful_connections++;
338 state_transition(rc, S_ACTIVE);
339 rc->last_connected = rc->state_entered;
340 } else if (retval != EAGAIN) {
341 VLOG_WARN("%s: connection failed (%s)", rc->name, strerror(retval));
342 disconnect(rc, retval);
343 } else if (timed_out(rc)) {
344 VLOG_WARN("%s: connection timed out", rc->name);
345 rc->backoff_deadline = TIME_MAX; /* Prevent resetting backoff. */
351 do_tx_work(struct rconn *rc)
356 while (rc->txq.n > 0) {
357 int error = try_send(rc);
363 poll_immediate_wake();
368 timeout_ACTIVE(const struct rconn *rc)
370 if (rc->probe_interval) {
371 unsigned int base = MAX(rc->last_received, rc->state_entered);
372 unsigned int arg = base + rc->probe_interval - rc->state_entered;
379 run_ACTIVE(struct rconn *rc)
382 unsigned int base = MAX(rc->last_received, rc->state_entered);
383 rconn_send(rc, make_echo_request(), NULL);
384 VLOG_DBG("%s: idle %u seconds, sending inactivity probe",
385 rc->name, (unsigned int) (time_now() - base));
386 state_transition(rc, S_IDLE);
394 timeout_IDLE(const struct rconn *rc)
396 return rc->probe_interval;
400 run_IDLE(struct rconn *rc)
403 question_connectivity(rc);
404 VLOG_ERR("%s: no response to inactivity probe after %u "
405 "seconds, disconnecting",
406 rc->name, elapsed_in_this_state(rc));
413 /* Performs whatever activities are necessary to maintain 'rc': if 'rc' is
414 * disconnected, attempts to (re)connect, backing off as necessary; if 'rc' is
415 * connected, attempts to send packets in the send queue, if any. */
417 rconn_run(struct rconn *rc)
421 old_state = rc->state;
423 #define STATE(NAME, VALUE) case S_##NAME: run_##NAME(rc); break;
429 } while (rc->state != old_state);
432 /* Causes the next call to poll_block() to wake up when rconn_run() should be
435 rconn_run_wait(struct rconn *rc)
437 unsigned int timeo = timeout(rc);
438 if (timeo != UINT_MAX) {
439 unsigned int expires = sat_add(rc->state_entered, timeo);
440 unsigned int remaining = sat_sub(expires, time_now());
441 poll_timer_wait(sat_mul(remaining, 1000));
444 if ((rc->state & (S_ACTIVE | S_IDLE)) && rc->txq.n) {
445 vconn_wait(rc->vconn, WAIT_SEND);
449 /* Attempts to receive a packet from 'rc'. If successful, returns the packet;
450 * otherwise, returns a null pointer. The caller is responsible for freeing
451 * the packet (with ofpbuf_delete()). */
453 rconn_recv(struct rconn *rc)
455 if (rc->state & (S_ACTIVE | S_IDLE)) {
456 struct ofpbuf *buffer;
457 int error = vconn_recv(rc->vconn, &buffer);
459 copy_to_monitor(rc, buffer);
460 if (is_admitted_msg(buffer)
461 || time_now() - rc->last_connected >= 30) {
462 rc->probably_admitted = true;
463 rc->last_admitted = time_now();
465 rc->last_received = time_now();
466 rc->packets_received++;
467 if (rc->state == S_IDLE) {
468 state_transition(rc, S_ACTIVE);
471 } else if (error != EAGAIN) {
472 disconnect(rc, error);
478 /* Causes the next call to poll_block() to wake up when a packet may be ready
479 * to be received by vconn_recv() on 'rc'. */
481 rconn_recv_wait(struct rconn *rc)
484 vconn_wait(rc->vconn, WAIT_RECV);
488 /* Sends 'b' on 'rc'. Returns 0 if successful (in which case 'b' is
489 * destroyed), or ENOTCONN if 'rc' is not currently connected (in which case
490 * the caller retains ownership of 'b').
492 * If 'n_queued' is non-null, then '*n_queued' will be incremented while the
493 * packet is in flight, then decremented when it has been sent (or discarded
494 * due to disconnection). Because 'b' may be sent (or discarded) before this
495 * function returns, the caller may not be able to observe any change in
498 * There is no rconn_send_wait() function: an rconn has a send queue that it
499 * takes care of sending if you call rconn_run(), which will have the side
500 * effect of waking up poll_block(). */
502 rconn_send(struct rconn *rc, struct ofpbuf *b, int *n_queued)
504 if (rconn_is_connected(rc)) {
505 copy_to_monitor(rc, b);
506 b->private = n_queued;
510 queue_push_tail(&rc->txq, b);
511 if (rc->txq.n == 1) {
520 /* Sends 'b' on 'rc'. Increments '*n_queued' while the packet is in flight; it
521 * will be decremented when it has been sent (or discarded due to
522 * disconnection). Returns 0 if successful, EAGAIN if '*n_queued' is already
523 * at least as large as 'queue_limit', or ENOTCONN if 'rc' is not currently
524 * connected. Regardless of return value, 'b' is destroyed.
526 * Because 'b' may be sent (or discarded) before this function returns, the
527 * caller may not be able to observe any change in '*n_queued'.
529 * There is no rconn_send_wait() function: an rconn has a send queue that it
530 * takes care of sending if you call rconn_run(), which will have the side
531 * effect of waking up poll_block(). */
533 rconn_send_with_limit(struct rconn *rc, struct ofpbuf *b,
534 int *n_queued, int queue_limit)
537 retval = *n_queued >= queue_limit ? EAGAIN : rconn_send(rc, b, n_queued);
544 /* Returns the total number of packets successfully sent on the underlying
545 * vconn. A packet is not counted as sent while it is still queued in the
546 * rconn, only when it has been successfuly passed to the vconn. */
548 rconn_packets_sent(const struct rconn *rc)
550 return rc->packets_sent;
553 /* Adds 'vconn' to 'rc' as a monitoring connection, to which all messages sent
554 * and received on 'rconn' will be copied. 'rc' takes ownership of 'vconn'. */
556 rconn_add_monitor(struct rconn *rc, struct vconn *vconn)
558 if (rc->n_monitors < ARRAY_SIZE(rc->monitors)) {
559 VLOG_WARN("new monitor connection from %s", vconn_get_name(vconn));
560 rc->monitors[rc->n_monitors++] = vconn;
562 VLOG_DBG("too many monitor connections, discarding %s",
563 vconn_get_name(vconn));
568 /* Returns 'rc''s name (the 'name' argument passed to rconn_new()). */
570 rconn_get_name(const struct rconn *rc)
575 /* Returns true if 'rconn' is connected or in the process of reconnecting,
576 * false if 'rconn' is disconnected and will not reconnect on its own. */
578 rconn_is_alive(const struct rconn *rconn)
580 return rconn->state != S_VOID;
583 /* Returns true if 'rconn' is connected, false otherwise. */
585 rconn_is_connected(const struct rconn *rconn)
587 return is_connected_state(rconn->state);
590 /* Returns 0 if 'rconn' is connected. Otherwise, if 'rconn' is in a "failure
591 * mode" (that is, it is not connected), returns the number of seconds that it
592 * has been in failure mode, ignoring any times that it connected but the
593 * controller's admission control policy caused it to be quickly
596 rconn_failure_duration(const struct rconn *rconn)
598 return rconn_is_connected(rconn) ? 0 : time_now() - rconn->last_admitted;
601 /* Returns the IP address of the peer, or 0 if the peer is not connected over
602 * an IP-based protocol or if its IP address is not known. */
604 rconn_get_ip(const struct rconn *rconn)
606 return rconn->vconn ? vconn_get_ip(rconn->vconn) : 0;
609 /* If 'rconn' can't connect to the peer, it could be for any number of reasons.
610 * Usually, one would assume it is because the peer is not running or because
611 * the network is partitioned. But it could also be because the network
612 * topology has changed, in which case the upper layer will need to reassess it
613 * (in particular, obtain a new IP address via DHCP and find the new location
614 * of the controller). When this appears that this might be the case, this
615 * function returns true. It also clears the questionability flag and prevents
616 * it from being set again for some time. */
618 rconn_is_connectivity_questionable(struct rconn *rconn)
620 bool questionable = rconn->questionable_connectivity;
621 rconn->questionable_connectivity = false;
625 /* Returns the total number of packets successfully received by the underlying
628 rconn_packets_received(const struct rconn *rc)
630 return rc->packets_received;
633 /* Returns a string representing the internal state of 'rc'. The caller must
634 * not modify or free the string. */
636 rconn_get_state(const struct rconn *rc)
638 return state_name(rc->state);
641 /* Returns the number of connection attempts made by 'rc', including any
642 * ongoing attempt that has not yet succeeded or failed. */
644 rconn_get_attempted_connections(const struct rconn *rc)
646 return rc->n_attempted_connections;
649 /* Returns the number of successful connection attempts made by 'rc'. */
651 rconn_get_successful_connections(const struct rconn *rc)
653 return rc->n_successful_connections;
656 /* Returns the time at which the last successful connection was made by
659 rconn_get_last_connection(const struct rconn *rc)
661 return rc->last_connected;
664 /* Returns the time at which 'rc' was created. */
666 rconn_get_creation_time(const struct rconn *rc)
668 return rc->creation_time;
671 /* Returns the approximate number of seconds that 'rc' has been connected. */
673 rconn_get_total_time_connected(const struct rconn *rc)
675 return (rc->total_time_connected
676 + (rconn_is_connected(rc) ? elapsed_in_this_state(rc) : 0));
679 /* Returns the current amount of backoff, in seconds. This is the amount of
680 * time after which the rconn will transition from BACKOFF to CONNECTING. */
682 rconn_get_backoff(const struct rconn *rc)
687 /* Returns the number of seconds spent in this state so far. */
689 rconn_get_state_elapsed(const struct rconn *rc)
691 return elapsed_in_this_state(rc);
694 /* Tries to send a packet from 'rc''s send buffer. Returns 0 if successful,
695 * otherwise a positive errno value. */
697 try_send(struct rconn *rc)
700 struct ofpbuf *next = rc->txq.head->next;
701 int *n_queued = rc->txq.head->private;
702 retval = vconn_send(rc->vconn, rc->txq.head);
704 if (retval != EAGAIN) {
705 disconnect(rc, retval);
713 queue_advance_head(&rc->txq, next);
717 /* Disconnects 'rc'. 'error' is used only for logging purposes. If it is
718 * nonzero, then it should be EOF to indicate the connection was closed by the
719 * peer in a normal fashion or a positive errno value. */
721 disconnect(struct rconn *rc, int error)
724 time_t now = time_now();
726 if (rc->state & (S_CONNECTING | S_ACTIVE | S_IDLE)) {
728 VLOG_WARN("%s: connection dropped (%s)",
729 rc->name, strerror(error));
730 } else if (error == EOF) {
732 VLOG_WARN("%s: connection closed by peer", rc->name);
735 VLOG_WARN("%s: connection dropped", rc->name);
737 vconn_close(rc->vconn);
742 if (now >= rc->backoff_deadline) {
745 rc->backoff = MIN(rc->max_backoff, MAX(1, 2 * rc->backoff));
746 VLOG_WARN("%s: waiting %d seconds before reconnect\n",
747 rc->name, rc->backoff);
749 rc->backoff_deadline = now + rc->backoff;
750 state_transition(rc, S_BACKOFF);
751 if (now - rc->last_connected > 60) {
752 question_connectivity(rc);
755 rconn_disconnect(rc);
759 /* Drops all the packets from 'rc''s send queue and decrements their queue
762 flush_queue(struct rconn *rc)
767 while (rc->txq.n > 0) {
768 struct ofpbuf *b = queue_pop_head(&rc->txq);
769 int *n_queued = b->private;
775 poll_immediate_wake();
779 elapsed_in_this_state(const struct rconn *rc)
781 return time_now() - rc->state_entered;
785 timeout(const struct rconn *rc)
788 #define STATE(NAME, VALUE) case S_##NAME: return timeout_##NAME(rc);
797 timed_out(const struct rconn *rc)
799 return time_now() >= sat_add(rc->state_entered, timeout(rc));
803 state_transition(struct rconn *rc, enum state state)
805 if (is_connected_state(state) && !is_connected_state(rc->state)) {
806 rc->probably_admitted = false;
808 if (rconn_is_connected(rc)) {
809 rc->total_time_connected += elapsed_in_this_state(rc);
811 VLOG_DBG("%s: entering %s", rc->name, state_name(state));
813 rc->state_entered = time_now();
817 question_connectivity(struct rconn *rc)
819 time_t now = time_now();
820 if (now - rc->last_questioned > 60) {
821 rc->questionable_connectivity = true;
822 rc->last_questioned = now;
827 copy_to_monitor(struct rconn *rc, const struct ofpbuf *b)
829 struct ofpbuf *clone = NULL;
833 for (i = 0; i < rc->n_monitors; ) {
834 struct vconn *vconn = rc->monitors[i];
837 clone = ofpbuf_clone(b);
839 retval = vconn_send(vconn, clone);
842 } else if (retval != EAGAIN) {
843 VLOG_DBG("%s: closing monitor connection to %s: %s",
844 rconn_get_name(rc), vconn_get_name(vconn),
846 rc->monitors[i] = rc->monitors[--rc->n_monitors];
851 ofpbuf_delete(clone);
855 is_connected_state(enum state state)
857 return (state & (S_ACTIVE | S_IDLE)) != 0;
861 is_admitted_msg(const struct ofpbuf *b)
863 struct ofp_header *oh = b->data;
864 uint8_t type = oh->type;
866 && (1u << type) & ((1u << OFPT_HELLO) |
868 (1u << OFPT_ECHO_REQUEST) |
869 (1u << OFPT_ECHO_REPLY) |
870 (1u << OFPT_VENDOR) |
871 (1u << OFPT_FEATURES_REQUEST) |
872 (1u << OFPT_FEATURES_REPLY) |
873 (1u << OFPT_GET_CONFIG_REQUEST) |
874 (1u << OFPT_GET_CONFIG_REPLY) |
875 (1u << OFPT_SET_CONFIG)));