Tor 0.4.9.0-alpha-dev
circuitpadding.c
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1/* Copyright (c) 2017 The Tor Project, Inc. */
2/* See LICENSE for licensing information */
3
4/**
5 * \file circuitpadding.c
6 * \brief Circuit-level padding implementation
7 *
8 * \details
9 *
10 * This file implements Tor proposal 254 "Padding Negotiation" which is heavily
11 * inspired by the paper "Toward an Efficient Website Fingerprinting Defense"
12 * by M. Juarez, M. Imani, M. Perry, C. Diaz, M. Wright.
13 *
14 * In particular the code in this file describes mechanisms for clients to
15 * negotiate various types of circuit-level padding from relays.
16 *
17 * Each padding type is described by a state machine (circpad_machine_spec_t),
18 * which is also referred as a "padding machine" in this file. Currently,
19 * these state machines are hardcoded in the source code (e.g. see
20 * circpad_machines_init()), but in the future we will be able to
21 * serialize them in the torrc or the consensus.
22 *
23 * As specified by prop#254, clients can negotiate padding with relays by using
24 * PADDING_NEGOTIATE cells. After successful padding negotiation, padding
25 * machines are assigned to the circuit in their mutable form as a
26 * circpad_machine_runtime_t.
27 *
28 * Each state of a padding state machine can be either:
29 * - A histogram that specifies inter-arrival padding delays.
30 * - Or a parametrized probability distribution that specifies inter-arrival
31 * delays (see circpad_distribution_type_t).
32 *
33 * Padding machines start from the START state and finish with the END
34 * state. They can transition between states using the events in
35 * circpad_event_t.
36 *
37 * When a padding machine reaches the END state, it gets wiped from the circuit
38 * so that other padding machines can take over if needed (see
39 * circpad_machine_spec_transitioned_to_end()).
40 *
41 ****************************
42 * General notes:
43 *
44 * All used machines should be heap allocated and placed into
45 * origin_padding_machines/relay_padding_machines so that they get correctly
46 * cleaned up by the circpad_free_all() function.
47 **/
48
49#define CIRCUITPADDING_PRIVATE
50
51#include <math.h>
52#include "lib/math/fp.h"
53#include "lib/math/prob_distr.h"
54#include "core/or/or.h"
57#include "core/or/circuitlist.h"
58#include "core/or/circuituse.h"
60#include "core/or/relay.h"
63
64#include "core/or/channel.h"
65
67#include "lib/defs/time.h"
69
71#include "core/or/circuit_st.h"
73#include "core/or/or_circuit_st.h"
76#include "core/or/cell_st.h"
80
82
83#include "app/config/config.h"
84
86 origin_circuit_t *circ);
87static void circpad_setup_machine_on_circ(circuit_t *on_circ,
88 const circpad_machine_spec_t *machine);
90
93
94/** Cached consensus params */
96static uint8_t circpad_padding_reduced;
97static uint8_t circpad_global_max_padding_percent;
98static uint16_t circpad_global_allowed_cells;
99static uint16_t circpad_max_circ_queued_cells;
100
101/** Global cell counts, for rate limiting */
103static uint64_t circpad_global_nonpadding_sent;
104
105/** This is the list of circpad_machine_spec_t's parsed from consensus and
106 * torrc that have origin_side == 1 (ie: are for client side).
107 *
108 * The machines in this smartlist are considered immutable and they are used
109 * as-is by circuits so they should not change or get deallocated in Tor's
110 * runtime and as long as circuits are alive. */
112
113/** This is the list of circpad_machine_spec_t's parsed from consensus and
114 * torrc that have origin_side == 0 (ie: are for relay side).
115 *
116 * The machines in this smartlist are considered immutable and they are used
117 * as-is by circuits so they should not change or get deallocated in Tor's
118 * runtime and as long as circuits are alive. */
120
121#ifndef COCCI
122/** Loop over the current padding state machines using <b>loop_var</b> as the
123 * loop variable. */
124#define FOR_EACH_CIRCUIT_MACHINE_BEGIN(loop_var) \
125 STMT_BEGIN \
126 for (int loop_var = 0; loop_var < CIRCPAD_MAX_MACHINES; loop_var++) {
127#define FOR_EACH_CIRCUIT_MACHINE_END } STMT_END ;
128
129/** Loop over the current active padding state machines using <b>loop_var</b>
130 * as the loop variable. If a machine is not active, skip it. */
131#define FOR_EACH_ACTIVE_CIRCUIT_MACHINE_BEGIN(loop_var, circ) \
132 FOR_EACH_CIRCUIT_MACHINE_BEGIN(loop_var) \
133 if (!(circ)->padding_info[loop_var]) \
134 continue;
135#define FOR_EACH_ACTIVE_CIRCUIT_MACHINE_END } STMT_END ;
136#endif /* !defined(COCCI) */
137
138/**
139 * Free the machineinfo at an index
140 */
141static void
143{
144 if (circ->padding_info[idx]) {
145 log_fn(LOG_INFO,LD_CIRC, "Freeing padding info idx %d on circuit %u (%d)",
146 idx, CIRCUIT_IS_ORIGIN(circ) ?
147 TO_ORIGIN_CIRCUIT(circ)->global_identifier : 0,
148 circ->purpose);
149
150 tor_free(circ->padding_info[idx]->histogram);
151 timer_free(circ->padding_info[idx]->padding_timer);
152 tor_free(circ->padding_info[idx]);
153 }
154}
155
156/**
157 * Return true if circpad has decided to hold the circuit open for additional
158 * padding. This function is used to take and retain ownership of certain
159 * types of circuits that have padding machines on them, that have been passed
160 * to circuit_mark_for_close().
161 *
162 * circuit_mark_for_close() calls this function to ask circpad if any padding
163 * machines want to keep the circuit open longer to pad.
164 *
165 * Any non-measurement circuit that was closed for a normal, non-error reason
166 * code may be held open for up to CIRCPAD_DELAY_INFINITE microseconds between
167 * network-driven cell events.
168 *
169 * After CIRCPAD_DELAY_INFINITE microseconds of silence on a circuit, this
170 * function will no longer hold it open (it will return 0 regardless of
171 * what the machines ask for, and thus circuit_expire_old_circuits_clientside()
172 * will close the circuit after roughly 1.25hr of idle time, maximum,
173 * regardless of the padding machine state.
174 */
175int
177{
178 /* If the circuit purpose is measurement or path bias, don't
179 * hold it open */
182 return 0;
183 }
184
185 /* If the circuit is closed for any reason other than these three valid,
186 * client-side close reasons, do not try to keep it open. It is probably
187 * damaged or unusable. Note this is OK with vanguards because
188 * controller-closed circuits have REASON=REQUESTED, so vanguards-closed
189 * circuits will not be held open (we want them to close ASAP). */
190 if (!(reason == END_CIRC_REASON_NONE ||
191 reason == END_CIRC_REASON_FINISHED ||
192 reason == END_CIRC_REASON_IP_NOW_REDUNDANT)) {
193 return 0;
194 }
195
198 if (!mi) {
199 continue; // No padding runtime info; check next machine
200 }
201
203
204 /* If we're in END state (NULL here), then check next machine */
205 if (!state) {
206 continue; // check next machine
207 }
208
209 /* If the machine does not want to control the circuit close itself, then
210 * check the next machine */
211 if (!circ->padding_machine[i]->manage_circ_lifetime) {
212 continue; // check next machine
213 }
214
215 /* If the machine has reached the END state, we can close. Check next
216 * machine. */
217 if (mi->current_state == CIRCPAD_STATE_END) {
218 continue; // check next machine
219 }
220
221 log_info(LD_CIRC, "Circuit %d is not marked for close because of a "
222 "pending padding machine in index %d.",
223 CIRCUIT_IS_ORIGIN(circ) ?
224 TO_ORIGIN_CIRCUIT(circ)->global_identifier : 0, i);
225
226 /* If the machine has had no network events at all within the
227 * last circpad_delay_t timespan, it's in some deadlock state.
228 * Tell circuit_mark_for_close() that we don't own it anymore.
229 * This will allow circuit_expire_old_circuits_clientside() to
230 * close it.
231 */
232 if (circ->padding_info[i]->last_cell_time_sec +
234 log_notice(LD_BUG, "Circuit %d was not marked for close because of a "
235 "pending padding machine in index %d for over an hour. "
236 "Circuit is a %s",
237 CIRCUIT_IS_ORIGIN(circ) ?
238 TO_ORIGIN_CIRCUIT(circ)->global_identifier : 0,
240
241 return 0; // abort timer reached; mark the circuit for close now
242 }
243
244 /* If we weren't marked dirty yet, let's pretend we're dirty now.
245 * ("Dirty" means that a circuit has been used for application traffic
246 * by Tor.. Dirty circuits have different expiry times, and are not
247 * considered in counts of built circuits, etc. By claiming that we're
248 * dirty, the rest of Tor will make decisions as if we were actually
249 * used by application data.
250 *
251 * This is most important for circuit_expire_old_circuits_clientside(),
252 * where we want that function to expire us after the padding machine
253 * has shut down, but using the MaxCircuitDirtiness timer instead of
254 * the idle circuit timer (again, we want this because we're not
255 * supposed to look idle to Guard nodes that can see our lifespan). */
256 if (!circ->timestamp_dirty) {
258 if (circ->conflux && CIRCUIT_IS_ORIGIN(circ))
260 }
261
262 /* Take ownership of the circuit */
264
265 return 1;
266 } FOR_EACH_ACTIVE_CIRCUIT_MACHINE_END;
267
268 return 0; // No machine wanted to keep the circuit open; mark for close
269}
270
271/**
272 * Free all the machineinfos in <b>circ</b> that match <b>machine_num</b>.
273 *
274 * If machine_ctr is non-zero, also make sure it matches the padding_info's
275 * machine counter before freeing.
276 *
277 * Returns true if any machineinfos with that number were freed.
278 * False otherwise. */
279static int
281 uint32_t machine_ctr)
282{
283 int found = 0;
285 if (circ->padding_machine[i] &&
286 circ->padding_machine[i]->machine_num == machine_num) {
287 /* If machine_ctr is non-zero, make sure it matches too. This
288 * is to ensure that old STOP messages don't shutdown newer machines. */
289 if (machine_ctr && circ->padding_info[i] &&
290 circ->padding_info[i]->machine_ctr != machine_ctr) {
291 log_info(LD_CIRC,
292 "Padding shutdown for wrong (old?) machine ctr: %u vs %u",
293 machine_ctr, circ->padding_info[i]->machine_ctr);
294 } else {
296 circ->padding_machine[i] = NULL;
297 found = 1;
298 }
299 }
300 } FOR_EACH_CIRCUIT_MACHINE_END;
301
302 return found;
303}
304
305/**
306 * Free all padding machines and mutable info associated with circuit
307 */
308void
310{
313 } FOR_EACH_CIRCUIT_MACHINE_END;
314}
315
316/**
317 * Allocate a new mutable machineinfo structure.
318 */
320circpad_circuit_machineinfo_new(circuit_t *on_circ, int machine_index)
321{
323 tor_malloc_zero(sizeof(circpad_machine_runtime_t));
324 mi->machine_index = machine_index;
325 mi->on_circ = on_circ;
327 mi->machine_ctr = on_circ->padding_machine_ctr;
328
329 return mi;
330}
331
332/**
333 * Return the circpad_state_t for the current state based on the
334 * mutable info.
335 *
336 * This function returns NULL when the machine is in the end state or in an
337 * invalid state.
338 */
341{
342 const circpad_machine_spec_t *machine = CIRCPAD_GET_MACHINE(mi);
343
344 if (mi->current_state == CIRCPAD_STATE_END) {
345 return NULL;
346 } else if (BUG(mi->current_state >= machine->num_states)) {
348 "Invalid circuit padding state %d",
349 mi->current_state);
350
351 return NULL;
352 }
353
354 return &machine->states[mi->current_state];
355}
356
357/**
358 * Get the lower bound of a histogram bin.
359 *
360 * You can obtain the upper bound using histogram_get_bin_upper_bound().
361 *
362 * This function can also be called with 'bin' set to a value equal or greater
363 * than histogram_len in which case the infinity bin is chosen and
364 * CIRCPAD_DELAY_INFINITE is returned.
365 */
369{
371 circpad_delay_t rtt_add_usec = 0;
372
373 /* Our state should have been checked to be non-null by the caller
374 * (circpad_machine_remove_token()) */
375 if (BUG(state == NULL)) {
377 }
378
379 /* The infinity bin has an upper bound of infinity, so make sure we return
380 * that if they ask for it. */
381 if (bin > CIRCPAD_INFINITY_BIN(state)) {
383 }
384
385 /* If we are using an RTT estimate, consider it as well. */
386 if (state->use_rtt_estimate) {
387 rtt_add_usec = mi->rtt_estimate_usec;
388 }
389
390 return state->histogram_edges[bin] + rtt_add_usec;
391}
392
393/**
394 * Like circpad_histogram_bin_to_usec() but return the upper bound of bin.
395 * (The upper bound is included in the bin.)
396 */
400{
401 return circpad_histogram_bin_to_usec(mi, bin+1) - 1;
402}
403
404/** Return the midpoint of the histogram bin <b>bin_index</b>. */
405static circpad_delay_t
407 int bin_index)
408{
409 circpad_delay_t left_bound = circpad_histogram_bin_to_usec(mi, bin_index);
410 circpad_delay_t right_bound = histogram_get_bin_upper_bound(mi, bin_index);
411
412 return left_bound + (right_bound - left_bound)/2;
413}
414
415/**
416 * Return the bin that contains the usec argument.
417 * "Contains" is defined as us in [lower, upper).
418 *
419 * This function will never return the infinity bin (histogram_len-1), in order
420 * to simplify the rest of the code, so if a usec is provided that falls above
421 * the highest non-infinity bin, that bin index will be returned.
422 */
425 circpad_delay_t usec)
426{
428 circpad_delay_t rtt_add_usec = 0;
430
431 /* Our state should have been checked to be non-null by the caller
432 * (circpad_machine_remove_token()) */
433 if (BUG(state == NULL)) {
434 return 0;
435 }
436
437 /* If we are using an RTT estimate, consider it as well. */
438 if (state->use_rtt_estimate) {
439 rtt_add_usec = mi->rtt_estimate_usec;
440 }
441
442 /* Walk through the bins and check the upper bound of each bin, if 'usec' is
443 * less-or-equal to that, return that bin. If rtt_estimate is enabled then
444 * add that to the upper bound of each bin.
445 *
446 * We don't want to return the infinity bin here, so don't go there. */
447 for (bin = 0 ; bin < CIRCPAD_INFINITY_BIN(state) ; bin++) {
448 if (usec <= histogram_get_bin_upper_bound(mi, bin) + rtt_add_usec) {
449 return bin;
450 }
451 }
452
453 /* We don't want to return the infinity bin here, so if we still didn't find
454 * the right bin, return the highest non-infinity bin */
455 return CIRCPAD_INFINITY_BIN(state)-1;
456}
457
458/**
459 * Return true if the machine supports token removal.
460 *
461 * Token removal is equivalent to having a mutable histogram in the
462 * circpad_machine_runtime_t mutable info. So while we're at it,
463 * let's assert that everything is consistent between the mutable
464 * runtime and the readonly machine spec.
465 */
466static inline int
468{
469 /* No runtime histogram == no token removal */
470 if (mi->histogram == NULL) {
471 /* Machines that don't want token removal are trying to avoid
472 * potentially expensive mallocs, extra memory accesses, and/or
473 * potentially expensive monotime calls. Let's minimize checks
474 * and keep this path fast. */
475 tor_assert_nonfatal(mi->histogram_len == 0);
476 return 0;
477 } else {
478 /* Machines that do want token removal are less sensitive to performance.
479 * Let's spend some time to check that our state is consistent and sane */
481 if (BUG(!state)) {
482 return 1;
483 }
484 tor_assert_nonfatal(state->token_removal != CIRCPAD_TOKEN_REMOVAL_NONE);
485 tor_assert_nonfatal(state->histogram_len == mi->histogram_len);
486 tor_assert_nonfatal(mi->histogram_len != 0);
487 return 1;
488 }
489
491 return 0;
492}
493
494/**
495 * This function frees any token bins allocated from a previous state
496 *
497 * Called after a state transition, or if the bins are empty.
498 */
499STATIC void
501{
503
504 /* If this state doesn't exist, or doesn't have token removal,
505 * free any previous state's runtime histogram, and bail.
506 *
507 * If we don't have a token removal strategy, we also don't need a runtime
508 * histogram and we rely on the immutable one in machine_spec_t. */
509 if (!state || state->token_removal == CIRCPAD_TOKEN_REMOVAL_NONE) {
510 if (mi->histogram) {
511 tor_free(mi->histogram);
512 mi->histogram = NULL;
513 mi->histogram_len = 0;
514 }
515 return;
516 }
517
518 /* Try to avoid re-mallocing if we don't really need to */
519 if (!mi->histogram || (mi->histogram
520 && mi->histogram_len != state->histogram_len)) {
521 tor_free(mi->histogram); // null ok
522 mi->histogram = tor_malloc_zero(sizeof(circpad_hist_token_t)
523 *state->histogram_len);
524 }
525 mi->histogram_len = state->histogram_len;
526
527 memcpy(mi->histogram, state->histogram,
528 sizeof(circpad_hist_token_t)*state->histogram_len);
529}
530
531/**
532 * Choose a length for this state (in cells), if specified.
533 */
534static void
536{
538 double length;
539
540 if (!state || state->length_dist.type == CIRCPAD_DIST_NONE) {
541 mi->state_length = CIRCPAD_STATE_LENGTH_INFINITE;
542 return;
543 }
544
546 length = MAX(0, length);
547 length += state->start_length;
548
549 if (state->max_length) {
550 length = MIN(length, state->max_length);
551 }
552
554
555 log_info(LD_CIRC, "State length sampled to %"PRIu64" for circuit %u",
558}
559
560/**
561 * Sample a value from our iat_dist, and clamp it safely
562 * to circpad_delay_t.
563 *
564 * Before returning, add <b>delay_shift</b> (can be zero) to the sampled value.
565 */
566static circpad_delay_t
568 circpad_delay_t delay_shift)
569{
570 double val = circpad_distribution_sample(state->iat_dist);
571 /* These comparisons are safe, because the output is in the range
572 * [0, 2**32), and double has a precision of 53 bits. */
573 /* We want a positive sample value */
574 val = MAX(0, val);
575 /* Respect the maximum sample setting */
576 val = MIN(val, state->dist_max_sample_usec);
577
578 /* Now apply the shift:
579 * This addition is exact: val is at most 2**32-1, delay_shift is at most
580 * 2**32-1, and doubles have a precision of 53 bits. */
581 val += delay_shift;
582
583 /* Clamp the distribution at infinite delay val */
585}
586
587/**
588 * Sample an expected time-until-next-packet delay from the histogram or
589 * probability distribution.
590 *
591 * A bin of the histogram is chosen with probability proportional to the number
592 * of tokens in each bin, and then a time value is chosen uniformly from that
593 * bin's [start,end) time range.
594 */
597{
599 const circpad_hist_token_t *histogram = NULL;
600 circpad_hist_index_t curr_bin = 0;
601 circpad_delay_t bin_start, bin_end;
602 /* These three must all be larger than circpad_hist_token_t, because
603 * we sum several circpad_hist_token_t values across the histogram */
604 uint64_t curr_weight = 0;
605 uint64_t histogram_total_tokens = 0;
606 uint64_t bin_choice;
607
608 tor_assert(state);
609
610 if (state->iat_dist.type != CIRCPAD_DIST_NONE) {
611 /* Sample from a fixed IAT distribution and return */
612 circpad_delay_t iat_delay_shift = state->use_rtt_estimate ?
613 mi->rtt_estimate_usec + state->dist_added_shift_usec :
614 state->dist_added_shift_usec;
615 return circpad_distribution_sample_iat_delay(state, iat_delay_shift);
616 } else if (circpad_is_token_removal_supported(mi)) {
617 histogram = mi->histogram;
618 for (circpad_hist_index_t b = 0; b < state->histogram_len; b++)
619 histogram_total_tokens += histogram[b];
620 } else {
621 /* We have a histogram, but it's immutable */
622 histogram = state->histogram;
623 histogram_total_tokens = state->histogram_total_tokens;
624 }
625
626 /* If we are out of tokens, don't schedule padding. */
627 if (!histogram_total_tokens) {
629 }
630
632 histogram_total_tokens);
633
634 /* Skip all the initial zero bins */
635 while (!histogram[curr_bin]) {
636 curr_bin++;
637 }
638 curr_weight = histogram[curr_bin];
639
640 // TODO: This is not constant-time. Pretty sure we don't
641 // really need it to be, though.
642 while (curr_weight < bin_choice) {
643 curr_bin++;
644 /* It should be impossible to run past the end of the histogram */
645 if (BUG(curr_bin >= state->histogram_len)) {
647 }
648 curr_weight += histogram[curr_bin];
649 }
650
651 /* Do some basic checking of the current bin we are in */
652 if (BUG(curr_bin >= state->histogram_len) ||
653 BUG(histogram[curr_bin] == 0)) {
655 }
656
657 // Store this index to remove the token upon callback.
659 mi->chosen_bin = curr_bin;
660 }
661
662 if (curr_bin >= CIRCPAD_INFINITY_BIN(state)) {
664 mi->histogram[curr_bin] > 0) {
665 mi->histogram[curr_bin]--;
666 }
667
668 // Infinity: Don't send a padding packet. Wait for a real packet
669 // and then see if our bins are empty or what else we should do.
671 }
672
673 tor_assert(curr_bin < CIRCPAD_INFINITY_BIN(state));
674
675 bin_start = circpad_histogram_bin_to_usec(mi, curr_bin);
676 /* We don't need to reduct 1 from the upper bound because the random range
677 * function below samples from [bin_start, bin_end) */
678 bin_end = circpad_histogram_bin_to_usec(mi, curr_bin+1);
679
680 /* Bin edges are monotonically increasing so this is a bug. Handle it. */
681 if (BUG(bin_start >= bin_end)) {
682 return bin_start;
683 }
684
686 bin_start, bin_end);
687}
688
689/**
690 * Sample a value from the specified probability distribution.
691 *
692 * Uses functions from src/lib/math/prob_distr.c .
693 */
694static double
696{
697 log_fn(LOG_DEBUG,LD_CIRC, "Sampling delay with distribution %d",
698 dist.type);
699
700 switch (dist.type) {
701 case CIRCPAD_DIST_NONE:
702 {
703 /* We should not get in here like this */
705 return 0;
706 }
707 case CIRCPAD_DIST_UNIFORM:
708 {
709 // param2 is upper bound, param1 is lower
710 const struct uniform_t my_uniform = {
711 .base = UNIFORM(my_uniform),
712 .a = dist.param1,
713 .b = dist.param2,
714 };
715 return dist_sample(&my_uniform.base);
716 }
717 case CIRCPAD_DIST_LOGISTIC:
718 {
719 /* param1 is Mu, param2 is sigma. */
720 const struct logistic_t my_logistic = {
721 .base = LOGISTIC(my_logistic),
722 .mu = dist.param1,
723 .sigma = dist.param2,
724 };
725 return dist_sample(&my_logistic.base);
726 }
727 case CIRCPAD_DIST_LOG_LOGISTIC:
728 {
729 /* param1 is Alpha, param2 is 1.0/Beta */
730 const struct log_logistic_t my_log_logistic = {
731 .base = LOG_LOGISTIC(my_log_logistic),
732 .alpha = dist.param1,
733 .beta = dist.param2,
734 };
735 return dist_sample(&my_log_logistic.base);
736 }
737 case CIRCPAD_DIST_GEOMETRIC:
738 {
739 /* param1 is 'p' (success probability) */
740 const struct geometric_t my_geometric = {
741 .base = GEOMETRIC(my_geometric),
742 .p = dist.param1,
743 };
744 return dist_sample(&my_geometric.base);
745 }
746 case CIRCPAD_DIST_WEIBULL:
747 {
748 /* param1 is k, param2 is Lambda */
749 const struct weibull_t my_weibull = {
750 .base = WEIBULL(my_weibull),
751 .k = dist.param1,
752 .lambda = dist.param2,
753 };
754 return dist_sample(&my_weibull.base);
755 }
756 case CIRCPAD_DIST_PARETO:
757 {
758 /* param1 is sigma, param2 is xi, no more params for mu so we use 0 */
759 const struct genpareto_t my_genpareto = {
760 .base = GENPARETO(my_genpareto),
761 .mu = 0,
762 .sigma = dist.param1,
763 .xi = dist.param2,
764 };
765 return dist_sample(&my_genpareto.base);
766 }
767 }
768
770 return 0;
771}
772
773/**
774 * Find the index of the first bin whose upper bound is
775 * greater than the target, and that has tokens remaining.
776 *
777 * Used for histograms with token removal.
778 */
781 circpad_delay_t target_bin_usec)
782{
784 target_bin_usec);
785
786 /* Don't remove from the infinity bin */
787 for (; bin < CIRCPAD_INFINITY_BIN(mi); bin++) {
788 if (mi->histogram[bin] &&
789 histogram_get_bin_upper_bound(mi, bin) >= target_bin_usec) {
790 return bin;
791 }
792 }
793
794 return mi->histogram_len;
795}
796
797/**
798 * Find the index of the first bin whose lower bound is lower or equal to
799 * <b>target_bin_usec</b>, and that still has tokens remaining.
800 *
801 * Used for histograms with token removal.
802 */
805 circpad_delay_t target_bin_usec)
806{
808 target_bin_usec);
809
810 for (; bin >= 0; bin--) {
811 if (mi->histogram[bin] &&
812 circpad_histogram_bin_to_usec(mi, bin) <= target_bin_usec) {
813 return bin;
814 }
815 }
816
817 return -1;
818}
819
820/**
821 * Remove a token from the first non-empty bin whose upper bound is
822 * greater than the target.
823 *
824 * Used for histograms with token removal.
825 */
826STATIC void
828 circpad_delay_t target_bin_usec)
829{
830 /* We need to remove the token from the first bin
831 * whose upper bound is greater than the target, and that
832 * has tokens remaining. */
834 target_bin_usec);
835
836 if (bin >= 0 && bin < CIRCPAD_INFINITY_BIN(mi)) {
837 if (!BUG(mi->histogram[bin] == 0)) {
838 mi->histogram[bin]--;
839 }
840 }
841}
842
843/**
844 * Remove a token from the first non-empty bin whose upper bound is
845 * lower than the target.
846 *
847 * Used for histograms with token removal.
848 */
849STATIC void
851 circpad_delay_t target_bin_usec)
852{
854 target_bin_usec);
855
856 if (bin >= 0 && bin < CIRCPAD_INFINITY_BIN(mi)) {
857 if (!BUG(mi->histogram[bin] == 0)) {
858 mi->histogram[bin]--;
859 }
860 }
861}
862
863/* Helper macro: Ensure that the bin has tokens available, and BUG out of the
864 * function if it's not the case. */
865#define ENSURE_BIN_CAPACITY(bin_index) \
866 if (BUG(mi->histogram[bin_index] == 0)) { \
867 return; \
868 }
869
870/**
871 * Remove a token from the closest non-empty bin to the target.
872 *
873 * If use_usec is true, measure "closest" in terms of the next closest bin
874 * midpoint.
875 *
876 * If it is false, use bin index distance only.
877 *
878 * Used for histograms with token removal.
879 */
880STATIC void
882 circpad_delay_t target_bin_usec,
883 bool use_usec)
884{
885 circpad_hist_index_t lower, higher, current;
886 circpad_hist_index_t bin_to_remove = -1;
887
888 lower = circpad_machine_first_lower_index(mi, target_bin_usec);
889 higher = circpad_machine_first_higher_index(mi, target_bin_usec);
890 current = circpad_histogram_usec_to_bin(mi, target_bin_usec);
891
892 /* Sanity check the results */
893 if (BUG(lower > current) || BUG(higher < current)) {
894 return;
895 }
896
897 /* Take care of edge cases first */
898 if (higher == mi->histogram_len && lower == -1) {
899 /* All bins are empty */
900 return;
901 } else if (higher == mi->histogram_len) {
902 /* All higher bins are empty */
903 ENSURE_BIN_CAPACITY(lower);
904 mi->histogram[lower]--;
905 return;
906 } else if (lower == -1) {
907 /* All lower bins are empty */
908 ENSURE_BIN_CAPACITY(higher);
909 mi->histogram[higher]--;
910 return;
911 }
912
913 /* Now handle the intermediate cases */
914 if (use_usec) {
915 /* Find the closest bin midpoint to the target */
917 circpad_delay_t higher_usec =
919
920 if (target_bin_usec < lower_usec) {
921 // Lower bin is closer
922 ENSURE_BIN_CAPACITY(lower);
923 bin_to_remove = lower;
924 } else if (target_bin_usec > higher_usec) {
925 // Higher bin is closer
926 ENSURE_BIN_CAPACITY(higher);
927 bin_to_remove = higher;
928 } else if (target_bin_usec-lower_usec > higher_usec-target_bin_usec) {
929 // Higher bin is closer
930 ENSURE_BIN_CAPACITY(higher);
931 bin_to_remove = higher;
932 } else {
933 // Lower bin is closer
934 ENSURE_BIN_CAPACITY(lower);
935 bin_to_remove = lower;
936 }
937 mi->histogram[bin_to_remove]--;
938 log_debug(LD_CIRC, "Removing token from bin %d", bin_to_remove);
939 return;
940 } else {
941 if (current - lower > higher - current) {
942 // Higher bin is closer
943 ENSURE_BIN_CAPACITY(higher);
944 mi->histogram[higher]--;
945 return;
946 } else {
947 // Lower bin is closer
948 ENSURE_BIN_CAPACITY(lower);
949 mi->histogram[lower]--;
950 return;
951 }
952 }
953}
954
955#undef ENSURE_BIN_CAPACITY
956
957/**
958 * Remove a token from the exact bin corresponding to the target.
959 *
960 * If it is empty, do nothing.
961 *
962 * Used for histograms with token removal.
963 */
964static void
966 circpad_delay_t target_bin_usec)
967{
969 target_bin_usec);
970
971 if (mi->histogram[bin] > 0)
972 mi->histogram[bin]--;
973}
974
975/**
976 * Check our state's cell limit count and tokens.
977 *
978 * Returns 1 if either limits are hit and we decide to change states,
979 * otherwise returns 0.
980 */
983{
984 uint32_t histogram_total_tokens = 0;
985
986 /* Check if bins empty. This requires summing up the current mutable
987 * machineinfo histogram token total and checking if it is zero.
988 * Machineinfo does not keep a running token count. We're assuming the
989 * extra space is not worth this short loop iteration.
990 *
991 * We also do not count infinity bin in histogram totals.
992 */
994 for (circpad_hist_index_t b = 0; b < CIRCPAD_INFINITY_BIN(mi); b++)
995 histogram_total_tokens += mi->histogram[b];
996
997 /* If we change state, we're done */
998 if (histogram_total_tokens == 0) {
999 if (circpad_internal_event_bins_empty(mi) == CIRCPAD_STATE_CHANGED)
1000 return CIRCPAD_STATE_CHANGED;
1001 }
1002 }
1003
1004 if (mi->state_length == 0) {
1006 }
1007
1008 return CIRCPAD_STATE_UNCHANGED;
1009}
1010
1011/**
1012 * Count that a padding packet was sent.
1013 *
1014 * This updates our state length count, our machine rate limit counts,
1015 * and if token removal is used, decrements the histogram.
1016 */
1017static inline void
1019{
1020 /* If we have a valid state length bound, consider it */
1021 if (mi->state_length != CIRCPAD_STATE_LENGTH_INFINITE &&
1022 !BUG(mi->state_length <= 0)) {
1023 mi->state_length--;
1024 }
1025
1026 /*
1027 * Update non-padding counts for rate limiting: We scale at UINT16_MAX
1028 * because we only use this for a percentile limit of 2 sig figs, and
1029 * space is scare in the machineinfo struct.
1030 */
1031 mi->padding_sent++;
1032 if (mi->padding_sent == UINT16_MAX) {
1033 mi->padding_sent /= 2;
1034 mi->nonpadding_sent /= 2;
1035 }
1036
1038
1039 /* If we have a mutable histogram, reduce the token count from
1040 * the chosen padding bin (this assumes we always send padding
1041 * when we intended to). */
1043 /* Check array bounds and token count before removing */
1044 if (!BUG(mi->chosen_bin >= mi->histogram_len) &&
1045 !BUG(mi->histogram[mi->chosen_bin] == 0)) {
1046 mi->histogram[mi->chosen_bin]--;
1047 }
1048 }
1049}
1050
1051/**
1052 * Count a nonpadding packet as being sent.
1053 *
1054 * This function updates our overhead accounting variables, as well
1055 * as decrements the state limit packet counter, if the latter was
1056 * flagged as applying to non-padding as well.
1057 */
1058static inline void
1060{
1061 /* Update non-padding counts for rate limiting: We scale at UINT16_MAX
1062 * because we only use this for a percentile limit of 2 sig figs, and
1063 * space is scare in the machineinfo struct. */
1064 mi->nonpadding_sent++;
1065 if (mi->nonpadding_sent == UINT16_MAX) {
1066 mi->padding_sent /= 2;
1067 mi->nonpadding_sent /= 2;
1068 }
1069
1070 /* Update any state packet length limits that apply */
1072
1073 /* Remove a token from the histogram, if applicable */
1075}
1076
1077/**
1078 * Decrement the state length counter for a non-padding packet.
1079 *
1080 * Only updates the state length if we're using that feature, we
1081 * have a state, and the machine wants to count non-padding packets
1082 * towards the state length.
1083 */
1084static inline void
1087{
1088 const circpad_state_t *state = NULL;
1089
1090 if (mi->state_length == CIRCPAD_STATE_LENGTH_INFINITE)
1091 return;
1092
1094
1095 /* If we are not in a padding state (like start or end), we're done */
1096 if (!state)
1097 return;
1098
1099 /* If we're enforcing a state length on non-padding packets,
1100 * decrement it */
1101 if (state->length_includes_nonpadding &&
1102 mi->state_length > 0) {
1103 mi->state_length--;
1104 }
1105}
1106
1107/**
1108 * When a non-padding packet arrives, remove a token from the bin
1109 * corresponding to the delta since last sent packet. If that bin
1110 * is empty, choose a token based on the specified removal strategy
1111 * in the state machine.
1112 */
1113STATIC void
1115{
1116 const circpad_state_t *state = NULL;
1117 circpad_time_t current_time;
1118 circpad_delay_t target_bin_usec;
1119
1120 /* Dont remove any tokens if there was no padding scheduled */
1121 if (!mi->padding_scheduled_at_usec) {
1122 return;
1123 }
1124
1126
1127 /* If we are not in a padding state (like start or end), we're done */
1128 if (!state)
1129 return;
1130 /* Don't remove any tokens if we're not doing token removal */
1132 return;
1133
1134 current_time = monotime_absolute_usec();
1135
1136 /* If we have scheduled padding some time in the future, we want to see what
1137 bin we are in at the current time */
1138 target_bin_usec = (circpad_delay_t)
1139 MIN((current_time - mi->padding_scheduled_at_usec),
1141
1142 /* We are treating this non-padding cell as a padding cell, so we cancel
1143 padding timer, if present. */
1148 }
1149
1150 /* Perform the specified token removal strategy */
1151 switch (state->token_removal) {
1153 circpad_machine_remove_closest_token(mi, target_bin_usec, 1);
1154 break;
1156 circpad_machine_remove_closest_token(mi, target_bin_usec, 0);
1157 break;
1159 circpad_machine_remove_lower_token(mi, target_bin_usec);
1160 break;
1162 circpad_machine_remove_higher_token(mi, target_bin_usec);
1163 break;
1165 circpad_machine_remove_exact(mi, target_bin_usec);
1166 break;
1168 default:
1170 log_warn(LD_BUG, "Circpad: Unknown token removal strategy %d",
1171 state->token_removal);
1172 break;
1173 }
1174}
1175
1176/**
1177 * Send a relay command with a relay cell payload on a circuit to
1178 * the particular hopnum.
1179 *
1180 * Hopnum starts at 1 (1=guard, 2=middle, 3=exit, etc).
1181 *
1182 * Payload may be null.
1183 *
1184 * Returns negative on error, 0 on success.
1185 */
1187circpad_send_command_to_hop,(origin_circuit_t *circ, uint8_t hopnum,
1188 uint8_t relay_command, const uint8_t *payload,
1189 ssize_t payload_len))
1190{
1191 crypt_path_t *target_hop = circuit_get_cpath_hop(circ, hopnum);
1192 signed_error_t ret;
1193
1194 /* Check that the cpath has the target hop */
1195 if (!target_hop) {
1196 log_fn(LOG_WARN, LD_BUG, "Padding circuit %u has %d hops, not %d",
1197 circ->global_identifier, circuit_get_cpath_len(circ), hopnum);
1198 return -1;
1199 }
1200
1201 /* Check that the target hop is opened */
1202 if (target_hop->state != CPATH_STATE_OPEN) {
1204 "Padding circuit %u has %d hops, not %d",
1205 circ->global_identifier,
1206 circuit_get_cpath_opened_len(circ), hopnum);
1207 return -1;
1208 }
1209
1210 /* Send the drop command to the second hop */
1211 ret = relay_send_command_from_edge(0, TO_CIRCUIT(circ), relay_command,
1212 (const char*)payload, payload_len,
1213 target_hop);
1214 return ret;
1215}
1216
1217/**
1218 * Callback helper to send a padding cell.
1219 *
1220 * This helper is called after our histogram-sampled delay period passes
1221 * without another packet being sent first. If a packet is sent before this
1222 * callback happens, it is canceled. So when we're called here, send padding
1223 * right away.
1224 *
1225 * If sending this padding cell forced us to transition states return
1226 * CIRCPAD_STATE_CHANGED. Otherwise return CIRCPAD_STATE_UNCHANGED.
1227 */
1230{
1231 circuit_t *circ = mi->on_circ;
1232 int machine_idx = mi->machine_index;
1236
1237 /* Make sure circuit didn't close on us */
1238 if (mi->on_circ->marked_for_close) {
1240 "Padding callback on circuit marked for close (%u). Ignoring.",
1243 return CIRCPAD_STATE_CHANGED;
1244 }
1245
1247
1248 if (CIRCUIT_IS_ORIGIN(mi->on_circ)) {
1250 CIRCPAD_GET_MACHINE(mi)->target_hopnum,
1251 RELAY_COMMAND_DROP, NULL, 0);
1252 log_info(LD_CIRC, "Callback: Sending padding to origin circuit %u"
1253 " (%d) [length: %"PRIu64"]",
1255 mi->on_circ->purpose, mi->state_length);
1256 } else {
1257 // If we're a non-origin circ, we can just send from here as if we're the
1258 // edge.
1259 if (TO_OR_CIRCUIT(circ)->p_chan_cells.n <= circpad_max_circ_queued_cells) {
1260 log_info(LD_CIRC, "Callback: Sending padding to circuit (%d)"
1261 " [length: %"PRIu64"]", mi->on_circ->purpose, mi->state_length);
1262 relay_send_command_from_edge(0, mi->on_circ, RELAY_COMMAND_DROP, NULL,
1263 0, NULL);
1265 } else {
1266 static ratelim_t cell_lim = RATELIM_INIT(600);
1268 "Too many cells (%d) in circ queue to send padding.",
1269 TO_OR_CIRCUIT(circ)->p_chan_cells.n);
1270 }
1271 }
1272
1273 /* This is a padding cell sent from the client or from the middle node,
1274 * (because it's invoked from circuitpadding.c) */
1276
1277 /* The circpad_cell_event_padding_sent() could cause us to transition.
1278 * Check that we still have a padding machineinfo, and then check our token
1279 * supply. */
1280 if (circ->padding_info[machine_idx] != NULL) {
1281 if (state != circ->padding_info[machine_idx]->current_state)
1282 return CIRCPAD_STATE_CHANGED;
1283 else
1284 return check_machine_token_supply(circ->padding_info[machine_idx]);
1285 } else {
1286 return CIRCPAD_STATE_CHANGED;
1287 }
1288}
1289
1290/**
1291 * Tor-timer compatible callback that tells us to send a padding cell.
1292 *
1293 * Timers are associated with circpad_machine_runtime_t's. When the machineinfo
1294 * is freed on a circuit, the timers are cancelled. Since the lifetime
1295 * of machineinfo is always longer than the timers, handles are not
1296 * needed.
1297 */
1298static void
1299circpad_send_padding_callback(tor_timer_t *timer, void *args,
1300 const struct monotime_t *time)
1301{
1303 (void)timer; (void)time;
1304
1305 if (mi && mi->on_circ) {
1308 } else {
1309 // This shouldn't happen (represents a timer leak)
1311 "Circuit closed while waiting for padding timer.");
1313 }
1314
1315 // TODO-MP-AP: Unify this counter with channelpadding for rephist stats
1316 //total_timers_pending--;
1317}
1318
1319/**
1320 * Cache our consensus parameters upon consensus update.
1321 */
1322void
1324{
1326 networkstatus_get_param(ns, "circpad_padding_disabled",
1327 0, 0, 1);
1328
1329 circpad_padding_reduced =
1330 networkstatus_get_param(ns, "circpad_padding_reduced",
1331 0, 0, 1);
1332
1333 circpad_global_allowed_cells =
1334 networkstatus_get_param(ns, "circpad_global_allowed_cells",
1335 0, 0, UINT16_MAX-1);
1336
1337 circpad_global_max_padding_percent =
1338 networkstatus_get_param(ns, "circpad_global_max_padding_pct",
1339 0, 0, 100);
1340
1341 circpad_max_circ_queued_cells =
1342 networkstatus_get_param(ns, "circpad_max_circ_queued_cells",
1343 CIRCWINDOW_START_MAX, 0, 50*CIRCWINDOW_START_MAX);
1344}
1345
1346/**
1347 * Return true if padding is allowed by torrc and consensus.
1348 */
1349static bool
1351{
1352 /* If padding has been disabled in the consensus, don't send any more
1353 * padding. Technically the machine should be shut down when the next
1354 * machine condition check happens, but machine checks only happen on
1355 * certain circuit events, and if padding is disabled due to some
1356 * network overload or DoS condition, we really want to stop ASAP. */
1357 if (circpad_padding_disabled || !get_options()->CircuitPadding) {
1358 return 0;
1359 }
1360
1361 return 1;
1362}
1363
1364/**
1365 * Check this machine against its padding limits, as well as global
1366 * consensus limits.
1367 *
1368 * We have two limits: a percent and a cell count. The cell count
1369 * limit must be reached before the percent is enforced (this is to
1370 * optionally allow very light padding of things like circuit setup
1371 * while there is no other traffic on the circuit).
1372 *
1373 * TODO: Don't apply limits to machines form torrc.
1374 *
1375 * Returns 1 if limits are set and we've hit them. Otherwise returns 0.
1376 */
1377STATIC bool
1379{
1380 const circpad_machine_spec_t *machine = CIRCPAD_GET_MACHINE(mi);
1381
1382 /* If machine_padding_pct is non-zero, and we've sent more
1383 * than the allowed count of padding cells, then check our
1384 * percent limits for this machine. */
1385 if (machine->max_padding_percent &&
1386 mi->padding_sent >= machine->allowed_padding_count) {
1387 uint32_t total_cells = mi->padding_sent + mi->nonpadding_sent;
1388
1389 /* Check the percent */
1390 if ((100*(uint32_t)mi->padding_sent) / total_cells >
1391 machine->max_padding_percent) {
1392 return 1; // limit is reached. Stop.
1393 }
1394 }
1395
1396 /* If circpad_max_global_padding_pct is non-zero, and we've
1397 * sent more than the global padding cell limit, then check our
1398 * global tor process percentage limit on padding. */
1399 if (circpad_global_max_padding_percent &&
1400 circpad_global_padding_sent >= circpad_global_allowed_cells) {
1401 uint64_t total_cells = circpad_global_padding_sent +
1402 circpad_global_nonpadding_sent;
1403
1404 /* Check the percent */
1405 if ((100*circpad_global_padding_sent) / total_cells >
1406 circpad_global_max_padding_percent) {
1407 return 1; // global limit reached. Stop.
1408 }
1409 }
1410
1411 return 0; // All good!
1412}
1413
1414/**
1415 * Schedule the next padding time according to the machineinfo on a
1416 * circuit.
1417 *
1418 * The histograms represent inter-packet-delay. Whenever you get an packet
1419 * event you should be scheduling your next timer (after cancelling any old
1420 * ones and updating tokens accordingly).
1421 *
1422 * Returns 1 if we decide to transition states (due to infinity bin),
1423 * 0 otherwise.
1424 */
1427{
1428 circpad_delay_t in_usec = 0;
1429 struct timeval timeout;
1430 tor_assert(mi);
1431
1432 /* Don't schedule padding if it is disabled */
1434 static ratelim_t padding_lim = RATELIM_INIT(600);
1435 log_fn_ratelim(&padding_lim,LOG_INFO,LD_CIRC,
1436 "Padding has been disabled, but machine still on circuit %"PRIu64
1437 ", %d",
1439 mi->on_circ->n_circ_id);
1440
1441 return CIRCPAD_STATE_UNCHANGED;
1442 }
1443
1444 /* Don't schedule padding if we are currently in dormant mode. */
1446 log_info(LD_CIRC, "Not scheduling padding because we are dormant.");
1447 return CIRCPAD_STATE_UNCHANGED;
1448 }
1449
1450 // Don't pad in end (but also don't cancel any previously
1451 // scheduled padding either).
1452 if (mi->current_state == CIRCPAD_STATE_END) {
1453 log_fn(LOG_INFO, LD_CIRC, "Padding end state on circuit %u",
1456 return CIRCPAD_STATE_UNCHANGED;
1457 }
1458
1459 /* Check our padding limits */
1461 if (CIRCUIT_IS_ORIGIN(mi->on_circ)) {
1463 "Padding machine has reached padding limit on circuit %u",
1465 } else {
1466 static ratelim_t padding_lim = RATELIM_INIT(600);
1467 log_fn_ratelim(&padding_lim,LOG_INFO,LD_CIRC,
1468 "Padding machine has reached padding limit on circuit %"PRIu64
1469 ", %d",
1471 mi->on_circ->n_circ_id);
1472 }
1473 return CIRCPAD_STATE_UNCHANGED;
1474 }
1475
1477 /* Cancel current timer (if any) */
1480 }
1481
1482 /* in_usec = in microseconds */
1483 in_usec = circpad_machine_sample_delay(mi);
1484 /* If we're using token removal, we need to know when the padding
1485 * was scheduled at, so we can remove the appropriate token if
1486 * a non-padding cell is sent before the padding timer expires.
1487 *
1488 * However, since monotime is unpredictably expensive, let's avoid
1489 * using it for machines that don't need token removal. */
1492 } else {
1494 }
1495 log_fn(LOG_INFO,LD_CIRC,"\tPadding in %u usec on circuit %u", in_usec,
1498
1499 // Don't schedule if we have infinite delay.
1500 if (in_usec == CIRCPAD_DELAY_INFINITE) {
1502 }
1503
1504 if (mi->state_length == 0) {
1505 /* If we're at length 0, that means we hit 0 after sending
1506 * a cell earlier, and emitted an event for it, but
1507 * for whatever reason we did not decide to change states then.
1508 * So maybe the machine is waiting for bins empty, or for an
1509 * infinity event later? That would be a strange machine,
1510 * but there's no reason to make it impossible. */
1511 return CIRCPAD_STATE_UNCHANGED;
1512 }
1513
1514 if (in_usec <= 0) {
1516 }
1517
1518 timeout.tv_sec = in_usec/TOR_USEC_PER_SEC;
1519 timeout.tv_usec = (in_usec%TOR_USEC_PER_SEC);
1520
1521 log_fn(LOG_INFO, LD_CIRC, "\tPadding circuit %u in %u sec, %u usec",
1524 (unsigned)timeout.tv_sec, (unsigned)timeout.tv_usec);
1525
1526 if (mi->padding_timer) {
1528 } else {
1529 mi->padding_timer =
1531 }
1534
1535 // TODO-MP-AP: Unify with channelpadding counter
1536 //rep_hist_padding_count_timers(++total_timers_pending);
1537
1538 return CIRCPAD_STATE_UNCHANGED;
1539}
1540
1541/**
1542 * If the machine transitioned to the END state, we need
1543 * to check to see if it wants us to shut it down immediately.
1544 * If it does, then we need to send the appropriate negotiation commands
1545 * depending on which side it is.
1546 *
1547 * After this function is called, mi may point to freed memory. Do
1548 * not access it.
1549 */
1550static void
1552{
1553 const circpad_machine_spec_t *machine = CIRCPAD_GET_MACHINE(mi);
1554 circuit_t *on_circ = mi->on_circ;
1555
1556 log_fn(LOG_INFO,LD_CIRC, "Padding machine in end state on circuit %u (%d)",
1557 CIRCUIT_IS_ORIGIN(on_circ) ?
1558 TO_ORIGIN_CIRCUIT(on_circ)->global_identifier : 0,
1559 on_circ->purpose);
1560
1561 /*
1562 * We allow machines to shut down and delete themselves as opposed
1563 * to just going back to START or waiting forever in END so that
1564 * we can handle the case where this machine started while it was
1565 * the only machine that matched conditions, but *since* then more
1566 * "higher ranking" machines now match the conditions, and would
1567 * be given a chance to take precedence over this one in
1568 * circpad_add_matching_machines().
1569 *
1570 * Returning to START or waiting forever in END would not give those
1571 * other machines a chance to be launched, where as shutting down
1572 * here does.
1573 */
1574 if (machine->should_negotiate_end) {
1575 if (machine->is_origin_side) {
1576 /* We free the machine info here so that we can be replaced
1577 * by a different machine. But we must leave the padding_machine
1578 * in place to wait for the negotiated response */
1579 uint32_t machine_ctr = mi->machine_ctr;
1581 machine->machine_index);
1583 machine->machine_num,
1584 machine->target_hopnum,
1585 CIRCPAD_COMMAND_STOP,
1586 machine_ctr);
1587 } else {
1588 uint32_t machine_ctr = mi->machine_ctr;
1590 machine->machine_index);
1592 machine->machine_num,
1593 CIRCPAD_COMMAND_STOP,
1594 CIRCPAD_RESPONSE_OK,
1595 machine_ctr);
1596 on_circ->padding_machine[machine->machine_index] = NULL;
1597 }
1598 }
1599}
1600
1601/**
1602 * Generic state transition function for padding state machines.
1603 *
1604 * Given an event and our mutable machine info, decide if/how to
1605 * transition to a different state, and perform actions accordingly.
1606 *
1607 * Returns 1 if we transition states, 0 otherwise.
1608 */
1612{
1613 const circpad_state_t *state =
1615
1616 /* If state is null we are in the end state. */
1617 if (!state) {
1618 /* If we in end state we don't pad no matter what. */
1619 return CIRCPAD_STATE_UNCHANGED;
1620 }
1621
1622 /* Check if this event is ignored or causes a cancel */
1623 if (state->next_state[event] == CIRCPAD_STATE_IGNORE) {
1624 return CIRCPAD_STATE_UNCHANGED;
1625 } else if (state->next_state[event] == CIRCPAD_STATE_CANCEL) {
1626 /* Check cancel events and cancel any pending padding */
1630 /* Cancel current timer (if any) */
1632 }
1633 return CIRCPAD_STATE_UNCHANGED;
1634 } else {
1635 circpad_statenum_t s = state->next_state[event];
1636 /* See if we need to transition to any other states based on this event.
1637 * Whenever a transition happens, even to our own state, we schedule
1638 * padding.
1639 *
1640 * So if a state only wants to schedule padding for an event, it specifies
1641 * a transition to itself. All non-specified events are ignored.
1642 */
1644 "Circuit %u circpad machine %d transitioning from %u to %u",
1647 mi->machine_index, mi->current_state, s);
1648
1649 /* If this is not the same state, switch and init tokens,
1650 * otherwise just reschedule padding. */
1651 if (mi->current_state != s) {
1652 mi->current_state = s;
1655
1656 /* If we transition to the end state, check to see
1657 * if this machine wants to be shut down at end */
1658 if (s == CIRCPAD_STATE_END) {
1660 /* We transitioned but we don't pad in end. Also, mi
1661 * may be freed. Returning STATE_CHANGED prevents us
1662 * from accessing it in any callers of this function. */
1663 return CIRCPAD_STATE_CHANGED;
1664 }
1665
1666 /* We transitioned to a new state, schedule padding */
1668 return CIRCPAD_STATE_CHANGED;
1669 }
1670
1671 /* We transitioned back to the same state. Schedule padding,
1672 * and inform if that causes a state transition. */
1674 }
1675
1676 return CIRCPAD_STATE_UNCHANGED;
1677}
1678
1679/**
1680 * Estimate the circuit RTT from the current middle hop out to the
1681 * end of the circuit.
1682 *
1683 * We estimate RTT by calculating the time between "receive" and
1684 * "send" at a middle hop. This is because we "receive" a cell
1685 * from the origin, and then relay it towards the exit before a
1686 * response comes back. It is that response time from the exit side
1687 * that we want to measure, so that we can make use of it for synthetic
1688 * response delays.
1689 */
1690static void
1693{
1694 /* Origin circuits don't estimate RTT. They could do it easily enough,
1695 * but they have no reason to use it in any delay calculations. */
1696 if (CIRCUIT_IS_ORIGIN(circ) || mi->stop_rtt_update)
1697 return;
1698
1699 /* If we already have a last received packet time, that means we
1700 * did not get a response before this packet. The RTT estimate
1701 * only makes sense if we do not have multiple packets on the
1702 * wire, so stop estimating if this is the second packet
1703 * back to back. However, for the first set of back-to-back
1704 * packets, we can wait until the very first response comes back
1705 * to us, to measure that RTT (for the response to optimistic
1706 * data, for example). Hence stop_rtt_update is only checked
1707 * in this received side function, and not in send side below.
1708 */
1709 if (mi->last_received_time_usec) {
1710 /* We also allow multiple back-to-back packets if the circuit is not
1711 * opened, to handle var cells.
1712 * XXX: Will this work with out var cell plans? Maybe not,
1713 * since we're opened at the middle hop as soon as we process
1714 * one var extend2 :/ */
1715 if (circ->state == CIRCUIT_STATE_OPEN) {
1717 "Stopping padding RTT estimation on circuit (%"PRIu64
1718 ", %d) after two back to back packets. Current RTT: %d",
1719 circ->n_chan ? circ->n_chan->global_identifier : 0,
1720 circ->n_circ_id, mi->rtt_estimate_usec);
1721 mi->stop_rtt_update = 1;
1722
1723 if (!mi->rtt_estimate_usec) {
1724 static ratelim_t rtt_lim = RATELIM_INIT(600);
1726 "Circuit got two cells back to back before estimating RTT.");
1727 }
1728 }
1729 } else {
1731 if (BUG(!state)) {
1732 return;
1733 }
1734
1735 /* Since monotime is unpredictably expensive, only update this field
1736 * if rtt estimates are needed. Otherwise, stop the rtt update. */
1737 if (state->use_rtt_estimate) {
1739 } else {
1740 /* Let's fast-path future decisions not to update rtt if the
1741 * feature is not in use. */
1742 mi->stop_rtt_update = 1;
1743 }
1744 }
1745}
1746
1747/**
1748 * Handles the "send" side of RTT calculation at middle nodes.
1749 *
1750 * This function calculates the RTT from the middle to the end
1751 * of the circuit by subtracting the last received cell timestamp
1752 * from the current time. It allows back-to-back cells until
1753 * the circuit is opened, to allow for var cell handshakes.
1754 * XXX: Check our var cell plans to make sure this will work.
1755 */
1756static void
1759{
1760 /* Origin circuits don't estimate RTT. They could do it easily enough,
1761 * but they have no reason to use it in any delay calculations. */
1762 if (CIRCUIT_IS_ORIGIN(circ))
1763 return;
1764
1765 /* If last_received_time_usec is non-zero, we are waiting for a response
1766 * from the exit side. Calculate the time delta and use it as RTT. */
1767 if (mi->last_received_time_usec) {
1770
1771 /* Reset the last RTT packet time, so we can tell if two cells
1772 * arrive back to back */
1774
1775 /* Use INT32_MAX to ensure the addition doesn't overflow */
1776 if (rtt_time >= INT32_MAX) {
1778 "Circuit padding RTT estimate overflowed: %"PRIu64
1779 " vs %"PRIu64, monotime_absolute_usec(),
1781 return;
1782 }
1783
1784 /* If the old RTT estimate is lower than this one, use this one, because
1785 * the circuit is getting longer. If this estimate is somehow
1786 * faster than the previous, then maybe that was network jitter, or a
1787 * bad monotonic clock source (so our ratchet returned a zero delta).
1788 * In that case, average them. */
1789 if (mi->rtt_estimate_usec < (circpad_delay_t)rtt_time) {
1790 mi->rtt_estimate_usec = (circpad_delay_t)rtt_time;
1791 } else {
1792 mi->rtt_estimate_usec += (circpad_delay_t)rtt_time;
1793 mi->rtt_estimate_usec /= 2;
1794 }
1795 } else if (circ->state == CIRCUIT_STATE_OPEN) {
1796 /* If last_received_time_usec is zero, then we have gotten two cells back
1797 * to back. Stop estimating RTT in this case. Note that we only
1798 * stop RTT update if the circuit is opened, to allow for RTT estimates
1799 * of var cells during circ setup. */
1800 if (!mi->rtt_estimate_usec && !mi->stop_rtt_update) {
1801 static ratelim_t rtt_lim = RATELIM_INIT(600);
1803 "Circuit sent two cells back to back before estimating RTT.");
1804 }
1805 mi->stop_rtt_update = 1;
1806 }
1807}
1808
1809/**
1810 * A "non-padding" cell has been sent from this endpoint. React
1811 * according to any padding state machines on the circuit.
1812 *
1813 * For origin circuits, this means we sent a cell into the network.
1814 * For middle relay circuits, this means we sent a cell towards the
1815 * origin.
1816 */
1817void
1819{
1820 /* Update global cell count */
1821 circpad_global_nonpadding_sent++;
1822
1823 /* If there are no machines then this loop should not iterate */
1825 /* First, update any timestamps */
1827 circpad_estimate_circ_rtt_on_send(on_circ, on_circ->padding_info[i]);
1828
1829 /* Then, do accounting */
1831
1832 /* Check to see if we've run out of tokens for this state already,
1833 * and if not, check for other state transitions */
1835 == CIRCPAD_STATE_UNCHANGED) {
1836 /* If removing a token did not cause a transition, check if
1837 * non-padding sent event should */
1839 CIRCPAD_EVENT_NONPADDING_SENT);
1840 }
1841 } FOR_EACH_ACTIVE_CIRCUIT_MACHINE_END;
1842}
1843
1844/** Check if this cell or circuit are related to circuit padding and handle
1845 * them if so. Return 0 if the cell was handled in this subsystem and does
1846 * not need any other consideration, otherwise return 1.
1847 */
1848int
1850 crypt_path_t *layer_hint,
1851 const relay_header_t *rh)
1852{
1853 /* First handle the padding commands, since we want to ignore any other
1854 * commands if this circuit is padding-specific. */
1855 switch (rh->command) {
1856 case RELAY_COMMAND_DROP:
1857 /* Already examined in circpad_deliver_recognized_relay_cell_events */
1858 return 0;
1859 case RELAY_COMMAND_PADDING_NEGOTIATE:
1861 return 0;
1862 case RELAY_COMMAND_PADDING_NEGOTIATED:
1863 if (circpad_handle_padding_negotiated(circ, cell, layer_hint) == 0)
1865 return 0;
1866 }
1867
1868 /* If this is a padding circuit we don't need to parse any other commands
1869 * than the padding ones. Just drop them to the floor.
1870 *
1871 * Note: we deliberately do not call circuit_read_valid_data() here. The
1872 * vanguards addon (specifically the 'bandguards' component's dropped cell
1873 * detection) will thus close this circuit, as it would for any other
1874 * unexpected cell. However, default tor will *not* close the circuit.
1875 *
1876 * This is intentional. We are not yet certain that is it optimal to keep
1877 * padding circuits open in cases like these, rather than closing them.
1878 * We suspect that continuing to pad is optimal against a passive classifier,
1879 * but as soon as the adversary is active (even as a client adversary) this
1880 * might change.
1881 *
1882 * So as a way forward, we log the cell command and circuit number, to
1883 * help us enumerate the most common instances of this in testing with
1884 * vanguards, to see which are common enough to verify and handle
1885 * properly.
1886 * - Mike
1887 */
1889 log_fn(LOG_PROTOCOL_WARN, LD_CIRC,
1890 "Ignored cell (%d) that arrived in padding circuit "
1891 " %u.", rh->command, CIRCUIT_IS_ORIGIN(circ) ?
1892 TO_ORIGIN_CIRCUIT(circ)->global_identifier : 0);
1893 return 0;
1894 }
1895
1896 return 1;
1897}
1898
1899/**
1900 * A "non-padding" cell has been received by this endpoint. React
1901 * according to any padding state machines on the circuit.
1902 *
1903 * For origin circuits, this means we read a cell from the network.
1904 * For middle relay circuits, this means we received a cell from the
1905 * origin.
1906 */
1907void
1909{
1911 /* First, update any timestamps */
1914
1916 CIRCPAD_EVENT_NONPADDING_RECV);
1917 } FOR_EACH_ACTIVE_CIRCUIT_MACHINE_END;
1918}
1919
1920/**
1921 * A padding cell has been sent from this endpoint. React
1922 * according to any padding state machines on the circuit.
1923 *
1924 * For origin circuits, this means we sent a cell into the network.
1925 * For middle relay circuits, this means we sent a cell towards the
1926 * origin.
1927 */
1928void
1930{
1932 /* Check to see if we've run out of tokens for this state already,
1933 * and if not, check for other state transitions */
1935 == CIRCPAD_STATE_UNCHANGED) {
1936 /* If removing a token did not cause a transition, check if
1937 * non-padding sent event should */
1938
1941 CIRCPAD_EVENT_PADDING_SENT);
1942 }
1943 } FOR_EACH_ACTIVE_CIRCUIT_MACHINE_END;
1944}
1945
1946/**
1947 * A padding cell has been received by this endpoint. React
1948 * according to any padding state machines on the circuit.
1949 *
1950 * For origin circuits, this means we read a cell from the network.
1951 * For middle relay circuits, this means we received a cell from the
1952 * origin.
1953 */
1954void
1956{
1957 /* identical to padding sent */
1961 CIRCPAD_EVENT_PADDING_RECV);
1962 } FOR_EACH_ACTIVE_CIRCUIT_MACHINE_END;
1963}
1964
1965/**
1966 * An "infinite" delay has ben chosen from one of our histograms.
1967 *
1968 * "Infinite" delays mean don't send padding -- but they can also
1969 * mean transition to another state depending on the state machine
1970 * definitions. Check the rules and react accordingly.
1971 *
1972 * Return 1 if we decide to transition, 0 otherwise.
1973 */
1976{
1977 return circpad_machine_spec_transition(mi, CIRCPAD_EVENT_INFINITY);
1978}
1979
1980/**
1981 * All of the bins of our current state's histogram's are empty.
1982 *
1983 * Check to see if this means transition to another state, and if
1984 * not, refill the tokens.
1985 *
1986 * Return 1 if we decide to transition, 0 otherwise.
1987 */
1990{
1991 if (circpad_machine_spec_transition(mi, CIRCPAD_EVENT_BINS_EMPTY)
1992 == CIRCPAD_STATE_CHANGED) {
1993 return CIRCPAD_STATE_CHANGED;
1994 } else {
1995 /* If we dont transition, then we refill the tokens */
1997 return CIRCPAD_STATE_UNCHANGED;
1998 }
1999}
2000
2001/**
2002 * This state has used up its cell count. Emit the event and
2003 * see if we transition.
2004 *
2005 * Return 1 if we decide to transition, 0 otherwise.
2006 */
2009{
2010 return circpad_machine_spec_transition(mi, CIRCPAD_EVENT_LENGTH_COUNT);
2011}
2012
2013/**
2014 * Returns true if the circuit matches the conditions.
2015 */
2016static inline bool
2018 const circpad_machine_spec_t *machine)
2019{
2020 /* If padding is disabled, no machines should match/apply. This has
2021 * the effect of shutting down all machines, and not adding any more. */
2022 if (circpad_padding_disabled || !get_options()->CircuitPadding)
2023 return 0;
2024
2025 /* If the consensus or our torrc has selected reduced connection padding,
2026 * then only allow this machine if it is flagged as acceptable under
2027 * reduced padding conditions */
2028 if (circpad_padding_reduced || get_options()->ReducedCircuitPadding) {
2029 if (!machine->conditions.reduced_padding_ok)
2030 return 0;
2031 }
2032
2033 if (!(circpad_circ_purpose_to_mask(TO_CIRCUIT(circ)->purpose)
2034 & machine->conditions.apply_purpose_mask))
2035 return 0;
2036
2037 if (machine->conditions.requires_vanguards) {
2038 const or_options_t *options = get_options();
2039
2040 /* Pinned middles are effectively vanguards */
2041 if (!(options->HSLayer2Nodes || options->HSLayer3Nodes))
2042 return 0;
2043 }
2044
2045 /* We check for any bits set in the circuit state mask so that machines
2046 * can say any of the following through their state bitmask:
2047 * "I want to apply to circuits with either streams or no streams"; OR
2048 * "I only want to apply to circuits with streams"; OR
2049 * "I only want to apply to circuits without streams". */
2050 if (!(circpad_circuit_state(circ) & machine->conditions.apply_state_mask))
2051 return 0;
2052
2054 return 0;
2055
2056 return 1;
2057}
2058
2059/**
2060 * Check to see if any of the keep conditions still apply to this circuit.
2061 *
2062 * These conditions keep the machines active if they match, but do not
2063 * cause new machines to start up.
2064 */
2065static inline bool
2067 const circpad_machine_spec_t *machine)
2068{
2069 if ((circpad_circ_purpose_to_mask(TO_CIRCUIT(circ)->purpose)
2070 & machine->conditions.keep_purpose_mask))
2071 return 1;
2072
2073 if ((circpad_circuit_state(circ) & machine->conditions.keep_state_mask))
2074 return 1;
2075
2076 return 0;
2077}
2078
2079/**
2080 * Returns a minimized representation of the circuit state.
2081 *
2082 * The padding code only cares if the circuit is building,
2083 * opened, used for streams, and/or still has relay early cells.
2084 * This returns a bitmask of all state properties that apply to
2085 * this circuit.
2086 */
2087static inline
2090{
2091 circpad_circuit_state_t retmask = 0;
2092
2093 if (circ->p_streams)
2094 retmask |= CIRCPAD_CIRC_STREAMS;
2095 else
2096 retmask |= CIRCPAD_CIRC_NO_STREAMS;
2097
2098 /* We use has_opened to prevent cannibialized circs from flapping. */
2099 if (circ->has_opened)
2100 retmask |= CIRCPAD_CIRC_OPENED;
2101 else
2102 retmask |= CIRCPAD_CIRC_BUILDING;
2103
2104 if (circ->remaining_relay_early_cells > 0)
2105 retmask |= CIRCPAD_CIRC_HAS_RELAY_EARLY;
2106 else
2107 retmask |= CIRCPAD_CIRC_HAS_NO_RELAY_EARLY;
2108
2109 return retmask;
2110}
2111
2112/**
2113 * Convert a normal circuit purpose into a bitmask that we can
2114 * use for determining matching circuits.
2115 */
2117circpad_circ_purpose_to_mask(uint8_t circ_purpose)
2118{
2119 /* Treat OR circ purposes as ignored. They should not be passed here*/
2120 if (BUG(circ_purpose <= CIRCUIT_PURPOSE_OR_MAX_)) {
2121 return 0;
2122 }
2123
2124 /* Treat new client circuit purposes as "OMG ITS EVERYTHING".
2125 * This also should not happen */
2126 if (BUG(circ_purpose - CIRCUIT_PURPOSE_OR_MAX_ - 1 > 32)) {
2127 return CIRCPAD_PURPOSE_ALL;
2128 }
2129
2130 /* Convert the purpose to a bit position */
2131 return 1 << (circ_purpose - CIRCUIT_PURPOSE_OR_MAX_ - 1);
2132}
2133
2134/**
2135 * Shut down any machines whose conditions no longer match
2136 * the current circuit.
2137 */
2138static void
2140{
2141 circuit_t *circ = TO_CIRCUIT(on_circ);
2142
2144 /* We shut down a machine if neither the apply conditions
2145 * nor the keep conditions match. If either set of conditions match,
2146 * keep it around. */
2148 circ->padding_machine[i]) &&
2150 circ->padding_machine[i])) {
2151 uint32_t machine_ctr = circ->padding_info[i]->machine_ctr;
2152 // Clear machineinfo (frees timers)
2154 // Send padding negotiate stop
2156 circ->padding_machine[i]->machine_num,
2158 CIRCPAD_COMMAND_STOP,
2159 machine_ctr);
2160 }
2161 } FOR_EACH_ACTIVE_CIRCUIT_MACHINE_END;
2162}
2163
2164/**
2165 * Negotiate new machines that would apply to this circuit, given the machines
2166 * inside <b>machines_sl</b>.
2167 *
2168 * This function checks to see if we have any free machine indexes,
2169 * and for each free machine index, it initializes the most recently
2170 * added origin-side padding machine that matches the target machine
2171 * index and circuit conditions, and negotiates it with the appropriate
2172 * middle relay.
2173 */
2174STATIC void
2176 smartlist_t *machines_sl)
2177{
2178 circuit_t *circ = TO_CIRCUIT(on_circ);
2179
2180#ifdef TOR_UNIT_TESTS
2181 /* Tests don't have to init our padding machines */
2182 if (!machines_sl)
2183 return;
2184#endif
2185
2186 /* If padding negotiation failed before, do not try again */
2187 if (on_circ->padding_negotiation_failed)
2188 return;
2189
2191 /* If there is a padding machine info, this index is occupied.
2192 * No need to check conditions for this index. */
2193 if (circ->padding_info[i])
2194 continue;
2195
2196 /* We have a free machine index. Check the origin padding
2197 * machines in reverse order, so that more recently added
2198 * machines take priority over older ones. */
2201 machine) {
2202 /* Machine definitions have a specific target machine index.
2203 * This is so event ordering is deterministic with respect
2204 * to which machine gets events first when there are two
2205 * machines installed on a circuit. Make sure we only
2206 * add this machine if its target machine index is free. */
2207 if (machine->machine_index == i &&
2208 circpad_machine_conditions_apply(on_circ, machine)) {
2209
2210 // We can only replace this machine if the target hopnum
2211 // is the same, otherwise we'll get invalid data
2212 if (circ->padding_machine[i]) {
2213 if (circ->padding_machine[i]->target_hopnum !=
2214 machine->target_hopnum)
2215 continue;
2216 /* Replace it. (Don't free - is global). */
2217 circ->padding_machine[i] = NULL;
2218 }
2219
2220 /* Set up the machine immediately so that the slot is occupied.
2221 * We will tear it down on error return, or if there is an error
2222 * response from the relay. */
2223 circpad_setup_machine_on_circ(circ, machine);
2224 if (circpad_negotiate_padding(on_circ, machine->machine_num,
2225 machine->target_hopnum,
2226 CIRCPAD_COMMAND_START,
2227 circ->padding_machine_ctr) < 0) {
2228 log_info(LD_CIRC,
2229 "Padding not negotiated. Cleaning machine from circuit %u",
2230 CIRCUIT_IS_ORIGIN(circ) ?
2231 TO_ORIGIN_CIRCUIT(circ)->global_identifier : 0);
2233 circ->padding_machine[i] = NULL;
2234 on_circ->padding_negotiation_failed = 1;
2235 } else {
2236 /* Success. Don't try any more machines on this index */
2237 break;
2238 }
2239 }
2240 } SMARTLIST_FOREACH_END(machine);
2241 } FOR_EACH_CIRCUIT_MACHINE_END;
2242}
2243
2244/**
2245 * Event that tells us we added a hop to an origin circuit.
2246 *
2247 * This event is used to decide if we should create a padding machine
2248 * on a circuit.
2249 */
2250void
2252{
2253 /* Since our padding conditions do not specify a max_hops,
2254 * all we can do is add machines here */
2256}
2257
2258/**
2259 * Event that tells us that an origin circuit is now built.
2260 *
2261 * Shut down any machines that only applied to un-built circuits.
2262 * Activate any new ones.
2263 */
2264void
2266{
2269}
2270
2271/**
2272 * Circpad purpose changed event.
2273 *
2274 * Shut down any machines that don't apply to our circ purpose.
2275 * Activate any new ones that do.
2276 */
2277void
2279{
2282}
2283
2284/**
2285 * Event that tells us that an origin circuit is out of RELAY_EARLY
2286 * cells.
2287 *
2288 * Shut down any machines that only applied to RELAY_EARLY circuits.
2289 * Activate any new ones.
2290 */
2291void
2293{
2296}
2297
2298/**
2299 * Streams attached event.
2300 *
2301 * Called from link_apconn_to_circ() and handle_hs_exit_conn()
2302 *
2303 * Shut down any machines that only applied to machines without
2304 * streams. Activate any new ones.
2305 */
2306void
2308{
2311}
2312
2313/**
2314 * Streams detached event.
2315 *
2316 * Called from circuit_detach_stream()
2317 *
2318 * Shut down any machines that only applied to machines without
2319 * streams. Activate any new ones.
2320 */
2321void
2323{
2326}
2327
2328/**
2329 * Verify that padding is coming from the expected hop.
2330 *
2331 * Returns true if from_hop matches the target hop from
2332 * one of our padding machines.
2333 *
2334 * Returns false if we're not an origin circuit, or if from_hop
2335 * does not match one of the padding machines.
2336 */
2337bool
2339 crypt_path_t *from_hop)
2340{
2341 crypt_path_t *target_hop = NULL;
2342 if (!CIRCUIT_IS_ORIGIN(circ))
2343 return 0;
2344
2346 /* We have to check padding_machine and not padding_info/active
2347 * machines here because padding may arrive after we shut down a
2348 * machine. The info is gone, but the padding_machine waits
2349 * for the padding_negotiated response to come back. */
2350 if (!circ->padding_machine[i])
2351 continue;
2352
2353 target_hop = circuit_get_cpath_hop(TO_ORIGIN_CIRCUIT(circ),
2354 circ->padding_machine[i]->target_hopnum);
2355
2356 if (target_hop == from_hop)
2357 return 1;
2358 } FOR_EACH_CIRCUIT_MACHINE_END;
2359
2360 return 0;
2361}
2362
2363/**
2364 * Deliver circpad events for an "unrecognized cell".
2365 *
2366 * Unrecognized cells are sent to relays and are forwarded
2367 * onto the next hop of their circuits. Unrecognized cells
2368 * are by definition not padding. We need to tell relay-side
2369 * state machines that a non-padding cell was sent or received,
2370 * depending on the direction, so they can update their histograms
2371 * and decide to pad or not.
2372 */
2373void
2375 cell_direction_t dir)
2376{
2377 // We should never see unrecognized cells at origin.
2378 // Our caller emits a warn when this happens.
2379 if (CIRCUIT_IS_ORIGIN(circ)) {
2380 return;
2381 }
2382
2383 if (dir == CELL_DIRECTION_OUT) {
2384 /* When direction is out (away from origin), then we received non-padding
2385 cell coming from the origin to us. */
2387 } else if (dir == CELL_DIRECTION_IN) {
2388 /* It's in and not origin, so the cell is going away from us.
2389 * So we are relaying a non-padding cell towards the origin. */
2391 }
2392}
2393
2394/**
2395 * Deliver circpad events for "recognized" relay cells.
2396 *
2397 * Recognized cells are destined for this hop, either client or middle.
2398 * Check if this is a padding cell or not, and send the appropriate
2399 * received event.
2400 */
2401void
2403 uint8_t relay_command,
2404 crypt_path_t *layer_hint)
2405{
2406 if (relay_command == RELAY_COMMAND_DROP) {
2408
2409 if (CIRCUIT_IS_ORIGIN(circ)) {
2410 if (circpad_padding_is_from_expected_hop(circ, layer_hint)) {
2412 } else {
2413 /* This is unexpected padding. Ignore it for now. */
2414 return;
2415 }
2416 }
2417
2418 /* The cell should be recognized by now, which means that we are on the
2419 destination, which means that we received a padding cell. We might be
2420 the client or the Middle node, still, because leaky-pipe. */
2422 log_fn(LOG_INFO, LD_CIRC, "Got padding cell on %s circuit %u.",
2423 CIRCUIT_IS_ORIGIN(circ) ? "origin" : "non-origin",
2424 CIRCUIT_IS_ORIGIN(circ) ?
2425 TO_ORIGIN_CIRCUIT(circ)->global_identifier : 0);
2426 } else {
2427 /* We received a non-padding cell on the edge */
2429 }
2430}
2431
2432/**
2433 * Deliver circpad events for relay cells sent from us.
2434 *
2435 * If this is a padding cell, update our padding stats
2436 * and deliver the event. Otherwise just deliver the event.
2437 */
2438void
2440 uint8_t relay_command)
2441{
2442 /* RELAY_COMMAND_DROP is the multi-hop (aka circuit-level) padding cell in
2443 * tor. (CELL_PADDING is a channel-level padding cell, which is not relayed
2444 * or processed here).
2445 *
2446 * We do generate events for PADDING_NEGOTIATE and PADDING_NEGOTIATED cells.
2447 */
2448 if (relay_command == RELAY_COMMAND_DROP) {
2449 /* Optimization: The event for RELAY_COMMAND_DROP is sent directly
2450 * from circpad_send_padding_cell_for_callback(). This is to avoid
2451 * putting a cell_t and a relay_header_t on the stack repeatedly
2452 * if we decide to send a long train of padding cells back-to-back
2453 * with 0 delay. So we do nothing here. */
2454 return;
2455 } else {
2456 /* This is a non-padding cell sent from the client or from
2457 * this node. */
2459 }
2460}
2461
2462/**
2463 * Initialize the states array for a circpad machine.
2464 */
2465void
2467 circpad_statenum_t num_states)
2468{
2469 if (BUG(num_states > CIRCPAD_MAX_MACHINE_STATES)) {
2470 num_states = CIRCPAD_MAX_MACHINE_STATES;
2471 }
2472
2473 machine->num_states = num_states;
2474 machine->states = tor_malloc_zero(sizeof(circpad_state_t)*num_states);
2475
2476 /* Initialize the default next state for all events to
2477 * "ignore" -- if events aren't specified, they are ignored. */
2478 for (circpad_statenum_t s = 0; s < num_states; s++) {
2479 for (int e = 0; e < CIRCPAD_NUM_EVENTS; e++) {
2480 machine->states[s].next_state[e] = CIRCPAD_STATE_IGNORE;
2481 }
2482 }
2483}
2484
2485static void
2486circpad_setup_machine_on_circ(circuit_t *on_circ,
2487 const circpad_machine_spec_t *machine)
2488{
2489 if (CIRCUIT_IS_ORIGIN(on_circ) && !machine->is_origin_side) {
2491 "Can't set up non-origin machine on origin circuit!");
2492 return;
2493 }
2494
2495 if (!CIRCUIT_IS_ORIGIN(on_circ) && machine->is_origin_side) {
2497 "Can't set up origin machine on non-origin circuit!");
2498 return;
2499 }
2500
2501 IF_BUG_ONCE(on_circ->padding_machine[machine->machine_index] != NULL) {
2502 return;
2503 }
2504 IF_BUG_ONCE(on_circ->padding_info[machine->machine_index] != NULL) {
2505 return;
2506 }
2507
2508 /* Log message */
2509 if (CIRCUIT_IS_ORIGIN(on_circ)) {
2510 log_info(LD_CIRC, "Registering machine %s to origin circ %u (%d)",
2511 machine->name,
2512 TO_ORIGIN_CIRCUIT(on_circ)->global_identifier, on_circ->purpose);
2513 } else {
2514 log_info(LD_CIRC, "Registering machine %s to non-origin circ (%d)",
2515 machine->name, on_circ->purpose);
2516 }
2517
2518 /* Padding machine ctr starts at 1, so we increment this ctr first.
2519 * (machine ctr of 0 means "any machine").
2520 *
2521 * See https://bugs.tororject.org/30992. */
2522 on_circ->padding_machine_ctr++;
2523
2524 /* uint32 wraparound check: 0 is special, just wrap to 1 */
2525 if (on_circ->padding_machine_ctr == 0) {
2526 on_circ->padding_machine_ctr = 1;
2527 }
2528
2529 on_circ->padding_info[machine->machine_index] =
2531 on_circ->padding_machine[machine->machine_index] = machine;
2532}
2533
2534/** Validate a single state of a padding machine */
2535static bool
2537{
2538 int b;
2539 uint32_t tokens_count = 0;
2540 circpad_delay_t prev_bin_edge = 0;
2541
2542 /* We only validate histograms */
2543 if (!state->histogram_len) {
2544 return true;
2545 }
2546
2547 /* We need at least two bins in a histogram */
2548 if (state->histogram_len < 2) {
2549 log_warn(LD_CIRC, "You can't have a histogram with less than 2 bins");
2550 return false;
2551 }
2552
2553 /* For each machine state, if it's a histogram, make sure all the
2554 * histogram edges are well defined (i.e. are strictly monotonic). */
2555 for (b = 0 ; b < state->histogram_len ; b++) {
2556 /* Check that histogram edges are strictly increasing. Ignore the first
2557 * edge since it can be zero. */
2558 if (prev_bin_edge >= state->histogram_edges[b] && b > 0) {
2559 log_warn(LD_CIRC, "Histogram edges are not increasing [%u/%u]",
2560 prev_bin_edge, state->histogram_edges[b]);
2561 return false;
2562 }
2563
2564 prev_bin_edge = state->histogram_edges[b];
2565
2566 /* Also count the number of tokens as we go through the histogram states */
2567 tokens_count += state->histogram[b];
2568 }
2569 /* Verify that the total number of tokens is correct */
2570 if (tokens_count != state->histogram_total_tokens) {
2571 log_warn(LD_CIRC, "Histogram token count is wrong [%u/%u]",
2572 tokens_count, state->histogram_total_tokens);
2573 return false;
2574 }
2575
2576 return true;
2577}
2578
2579/** Basic validation of padding machine */
2580static bool
2582{
2583 int i;
2584
2585 /* Validate the histograms of the padding machine */
2586 for (i = 0 ; i < machine->num_states ; i++) {
2587 if (!padding_machine_state_is_valid(&machine->states[i])) {
2588 return false;
2589 }
2590 }
2591
2592 return true;
2593}
2594
2595/* Validate and register <b>machine</b> into <b>machine_list</b>. If
2596 * <b>machine_list</b> is NULL, then just validate. */
2597void
2598circpad_register_padding_machine(circpad_machine_spec_t *machine,
2599 smartlist_t *machine_list)
2600{
2601 if (!padding_machine_is_valid(machine)) {
2602 log_warn(LD_CIRC, "Machine #%u is invalid. Ignoring.",
2603 machine->machine_num);
2604 return;
2605 }
2606
2607 if (machine_list) {
2608 smartlist_add(machine_list, machine);
2609 }
2610}
2611
2612#ifdef TOR_UNIT_TESTS
2613/* These padding machines are only used for tests pending #28634. */
2614static void
2615circpad_circ_client_machine_init(void)
2616{
2617 circpad_machine_spec_t *circ_client_machine
2618 = tor_malloc_zero(sizeof(circpad_machine_spec_t));
2619
2620 circ_client_machine->conditions.min_hops = 2;
2621 circ_client_machine->conditions.apply_state_mask =
2622 CIRCPAD_CIRC_BUILDING|CIRCPAD_CIRC_OPENED|CIRCPAD_CIRC_HAS_RELAY_EARLY;
2623 circ_client_machine->conditions.apply_purpose_mask = CIRCPAD_PURPOSE_ALL;
2624 circ_client_machine->conditions.reduced_padding_ok = 1;
2625
2626 circ_client_machine->target_hopnum = 2;
2627 circ_client_machine->is_origin_side = 1;
2628
2629 /* Start, gap, burst */
2630 circpad_machine_states_init(circ_client_machine, 3);
2631
2632 circ_client_machine->states[CIRCPAD_STATE_START].
2633 next_state[CIRCPAD_EVENT_NONPADDING_RECV] = CIRCPAD_STATE_BURST;
2634
2635 circ_client_machine->states[CIRCPAD_STATE_BURST].
2636 next_state[CIRCPAD_EVENT_NONPADDING_RECV] = CIRCPAD_STATE_BURST;
2637 circ_client_machine->states[CIRCPAD_STATE_BURST].
2638 next_state[CIRCPAD_EVENT_PADDING_RECV] = CIRCPAD_STATE_BURST;
2639
2640 /* If we are in burst state, and we send a non-padding cell, then we cancel
2641 the timer for the next padding cell:
2642 We dont want to send fake extends when actual extends are going on */
2643 circ_client_machine->states[CIRCPAD_STATE_BURST].
2644 next_state[CIRCPAD_EVENT_NONPADDING_SENT] = CIRCPAD_STATE_CANCEL;
2645
2646 circ_client_machine->states[CIRCPAD_STATE_BURST].
2647 next_state[CIRCPAD_EVENT_BINS_EMPTY] = CIRCPAD_STATE_END;
2648
2649 circ_client_machine->states[CIRCPAD_STATE_BURST].token_removal =
2651
2652 circ_client_machine->states[CIRCPAD_STATE_BURST].histogram_len = 2;
2653 circ_client_machine->states[CIRCPAD_STATE_BURST].histogram_edges[0]= 500;
2654 circ_client_machine->states[CIRCPAD_STATE_BURST].histogram_edges[1]= 1000000;
2655
2656 /* We have 5 tokens in the histogram, which means that all circuits will look
2657 * like they have 7 hops (since we start this machine after the second hop,
2658 * and tokens are decremented for any valid hops, and fake extends are
2659 * used after that -- 2+5==7). */
2660 circ_client_machine->states[CIRCPAD_STATE_BURST].histogram[0] = 5;
2661
2662 circ_client_machine->states[CIRCPAD_STATE_BURST].histogram_total_tokens = 5;
2663
2664 circ_client_machine->machine_num = smartlist_len(origin_padding_machines);
2665 circpad_register_padding_machine(circ_client_machine,
2667}
2668
2669static void
2670circpad_circ_responder_machine_init(void)
2671{
2672 circpad_machine_spec_t *circ_responder_machine
2673 = tor_malloc_zero(sizeof(circpad_machine_spec_t));
2674
2675 /* Shut down the machine after we've sent enough packets */
2676 circ_responder_machine->should_negotiate_end = 1;
2677
2678 /* The relay-side doesn't care what hopnum it is, but for consistency,
2679 * let's match the client */
2680 circ_responder_machine->target_hopnum = 2;
2681 circ_responder_machine->is_origin_side = 0;
2682
2683 /* Start, gap, burst */
2684 circpad_machine_states_init(circ_responder_machine, 3);
2685
2686 /* This is the settings of the state machine. In the future we are gonna
2687 serialize this into the consensus or the torrc */
2688
2689 /* We transition to the burst state on padding receive and on non-padding
2690 * receive */
2691 circ_responder_machine->states[CIRCPAD_STATE_START].
2692 next_state[CIRCPAD_EVENT_PADDING_RECV] = CIRCPAD_STATE_BURST;
2693 circ_responder_machine->states[CIRCPAD_STATE_START].
2694 next_state[CIRCPAD_EVENT_NONPADDING_RECV] = CIRCPAD_STATE_BURST;
2695
2696 /* Inside the burst state we _stay_ in the burst state when a non-padding
2697 * is sent */
2698 circ_responder_machine->states[CIRCPAD_STATE_BURST].
2699 next_state[CIRCPAD_EVENT_NONPADDING_SENT] = CIRCPAD_STATE_BURST;
2700
2701 /* Inside the burst state we transition to the gap state when we receive a
2702 * padding cell */
2703 circ_responder_machine->states[CIRCPAD_STATE_BURST].
2704 next_state[CIRCPAD_EVENT_PADDING_RECV] = CIRCPAD_STATE_GAP;
2705
2706 /* These describe the padding charasteristics when in burst state */
2707
2708 /* use_rtt_estimate tries to estimate how long padding cells take to go from
2709 C->M, and uses that as what as the base of the histogram */
2710 circ_responder_machine->states[CIRCPAD_STATE_BURST].use_rtt_estimate = 1;
2711 /* The histogram is 2 bins: an empty one, and infinity */
2712 circ_responder_machine->states[CIRCPAD_STATE_BURST].histogram_len = 2;
2713 circ_responder_machine->states[CIRCPAD_STATE_BURST].histogram_edges[0]= 500;
2714 circ_responder_machine->states[CIRCPAD_STATE_BURST].histogram_edges[1] =
2715 1000000;
2716 /* During burst state we wait forever for padding to arrive.
2717
2718 We are waiting for a padding cell from the client to come in, so that we
2719 respond, and we imitate how extend looks like */
2720 circ_responder_machine->states[CIRCPAD_STATE_BURST].histogram[0] = 0;
2721 // Only infinity bin:
2722 circ_responder_machine->states[CIRCPAD_STATE_BURST].histogram[1] = 1;
2723 circ_responder_machine->states[CIRCPAD_STATE_BURST].
2724 histogram_total_tokens = 1;
2725
2726 /* From the gap state, we _stay_ in the gap state, when we receive padding
2727 * or non padding */
2728 circ_responder_machine->states[CIRCPAD_STATE_GAP].
2729 next_state[CIRCPAD_EVENT_PADDING_RECV] = CIRCPAD_STATE_GAP;
2730 circ_responder_machine->states[CIRCPAD_STATE_GAP].
2731 next_state[CIRCPAD_EVENT_NONPADDING_RECV] = CIRCPAD_STATE_GAP;
2732
2733 /* And from the gap state, we go to the end, when the bins are empty or a
2734 * non-padding cell is sent */
2735 circ_responder_machine->states[CIRCPAD_STATE_GAP].
2736 next_state[CIRCPAD_EVENT_BINS_EMPTY] = CIRCPAD_STATE_END;
2737 circ_responder_machine->states[CIRCPAD_STATE_GAP].
2738 next_state[CIRCPAD_EVENT_NONPADDING_SENT] = CIRCPAD_STATE_END;
2739
2740 // FIXME: Tune this histogram
2741
2742 /* The gap state is the delay you wait after you receive a padding cell
2743 before you send a padding response */
2744 circ_responder_machine->states[CIRCPAD_STATE_GAP].use_rtt_estimate = 1;
2745 circ_responder_machine->states[CIRCPAD_STATE_GAP].histogram_len = 6;
2746 /* Specify histogram bins */
2747 circ_responder_machine->states[CIRCPAD_STATE_GAP].histogram_edges[0]= 500;
2748 circ_responder_machine->states[CIRCPAD_STATE_GAP].histogram_edges[1]= 1000;
2749 circ_responder_machine->states[CIRCPAD_STATE_GAP].histogram_edges[2]= 2000;
2750 circ_responder_machine->states[CIRCPAD_STATE_GAP].histogram_edges[3]= 4000;
2751 circ_responder_machine->states[CIRCPAD_STATE_GAP].histogram_edges[4]= 8000;
2752 circ_responder_machine->states[CIRCPAD_STATE_GAP].histogram_edges[5]= 16000;
2753 /* Specify histogram tokens */
2754 circ_responder_machine->states[CIRCPAD_STATE_GAP].histogram[0] = 0;
2755 circ_responder_machine->states[CIRCPAD_STATE_GAP].histogram[1] = 1;
2756 circ_responder_machine->states[CIRCPAD_STATE_GAP].histogram[2] = 2;
2757 circ_responder_machine->states[CIRCPAD_STATE_GAP].histogram[3] = 2;
2758 circ_responder_machine->states[CIRCPAD_STATE_GAP].histogram[4] = 1;
2759 /* Total number of tokens */
2760 circ_responder_machine->states[CIRCPAD_STATE_GAP].histogram_total_tokens = 6;
2761
2762 circ_responder_machine->states[CIRCPAD_STATE_GAP].token_removal =
2764
2765 circ_responder_machine->machine_num = smartlist_len(relay_padding_machines);
2766 circpad_register_padding_machine(circ_responder_machine,
2768}
2769#endif /* defined(TOR_UNIT_TESTS) */
2770
2771/**
2772 * Initialize all of our padding machines.
2773 *
2774 * This is called at startup. It sets up some global machines, and then
2775 * loads some from torrc, and from the tor consensus.
2776 */
2777void
2779{
2780 tor_assert_nonfatal(origin_padding_machines == NULL);
2781 tor_assert_nonfatal(relay_padding_machines == NULL);
2782
2785
2786 /* Register machines for hiding client-side intro circuits */
2789
2790 /* Register machines for hiding client-side rendezvous circuits */
2793
2794 // TODO: Parse machines from consensus and torrc
2795#ifdef TOR_UNIT_TESTS
2796 circpad_circ_client_machine_init();
2797 circpad_circ_responder_machine_init();
2798#endif
2799}
2800
2801/**
2802 * Free our padding machines
2803 */
2804void
2806{
2810 m, tor_free(m->states); tor_free(m));
2811 smartlist_free(origin_padding_machines);
2812 }
2813
2817 m, tor_free(m->states); tor_free(m));
2818 smartlist_free(relay_padding_machines);
2819 }
2820}
2821
2822/**
2823 * Check the Protover info to see if a node supports padding.
2824 */
2825static bool
2827{
2828 if (node->rs) {
2829 log_fn(LOG_INFO, LD_CIRC, "Checking padding: %s",
2830 node->rs->pv.supports_hs_setup_padding ?
2831 "supported" : "unsupported");
2832 return node->rs->pv.supports_hs_setup_padding;
2833 }
2834
2835 log_fn(LOG_INFO, LD_CIRC, "Empty routerstatus in padding check");
2836 return 0;
2837}
2838
2839/**
2840 * Get a node_t for the nth hop in our circuit, starting from 1.
2841 *
2842 * Returns node_t from the consensus for that hop, if it is opened.
2843 * Otherwise returns NULL.
2844 */
2845MOCK_IMPL(STATIC const node_t *,
2847{
2848 crypt_path_t *iter = circuit_get_cpath_hop(circ, hop);
2849
2850 if (!iter || iter->state != CPATH_STATE_OPEN)
2851 return NULL;
2852
2854}
2855
2856/**
2857 * Return true if a particular circuit supports padding
2858 * at the desired hop.
2859 */
2860static bool
2862 int target_hopnum)
2863{
2864 const node_t *hop;
2865
2866 if (!(hop = circuit_get_nth_node(circ, target_hopnum))) {
2867 return 0;
2868 }
2869
2871}
2872
2873/**
2874 * Try to negotiate padding.
2875 *
2876 * Returns -1 on error, 0 on success.
2877 */
2880 circpad_machine_num_t machine,
2881 uint8_t target_hopnum,
2882 uint8_t command,
2883 uint32_t machine_ctr)
2884{
2885 circpad_negotiate_t type;
2886 cell_t cell;
2887 ssize_t len;
2888
2889 /* Check that the target hop lists support for padding in
2890 * its ProtoVer fields */
2891 if (!circpad_circuit_supports_padding(circ, target_hopnum)) {
2892 return -1;
2893 }
2894
2895 memset(&cell, 0, sizeof(cell_t));
2896 memset(&type, 0, sizeof(circpad_negotiate_t));
2897 // This gets reset to RELAY_EARLY appropriately by
2898 // relay_send_command_from_edge_. At least, it looks that way.
2899 // QQQ-MP-AP: Verify that.
2900 cell.command = CELL_RELAY;
2901
2902 circpad_negotiate_set_command(&type, command);
2903 circpad_negotiate_set_version(&type, 0);
2904 circpad_negotiate_set_machine_type(&type, machine);
2905 circpad_negotiate_set_machine_ctr(&type, machine_ctr);
2906
2907 if ((len = circpad_negotiate_encode(cell.payload, CELL_PAYLOAD_SIZE,
2908 &type)) < 0)
2909 return -1;
2910
2912 "Negotiating padding on circuit %u (%d), command %d, for ctr %u",
2913 circ->global_identifier, TO_CIRCUIT(circ)->purpose, command,
2914 machine_ctr);
2915
2916 return circpad_send_command_to_hop(circ, target_hopnum,
2917 RELAY_COMMAND_PADDING_NEGOTIATE,
2918 cell.payload, len);
2919}
2920
2921/**
2922 * Try to negotiate padding.
2923 *
2924 * Returns 1 if successful (or already set up), 0 otherwise.
2925 */
2926bool
2928 circpad_machine_num_t machine,
2929 uint8_t command,
2930 uint8_t response,
2931 uint32_t machine_ctr)
2932{
2933 circpad_negotiated_t type;
2934 cell_t cell;
2935 ssize_t len;
2936
2937 memset(&cell, 0, sizeof(cell_t));
2938 memset(&type, 0, sizeof(circpad_negotiated_t));
2939 // This gets reset to RELAY_EARLY appropriately by
2940 // relay_send_command_from_edge_. At least, it looks that way.
2941 // QQQ-MP-AP: Verify that.
2942 cell.command = CELL_RELAY;
2943
2944 circpad_negotiated_set_command(&type, command);
2945 circpad_negotiated_set_response(&type, response);
2946 circpad_negotiated_set_version(&type, 0);
2947 circpad_negotiated_set_machine_type(&type, machine);
2948 circpad_negotiated_set_machine_ctr(&type, machine_ctr);
2949
2950 if ((len = circpad_negotiated_encode(cell.payload, CELL_PAYLOAD_SIZE,
2951 &type)) < 0)
2952 return 0;
2953
2954 /* Use relay_send because we're from the middle to the origin. We don't
2955 * need to specify a target hop or layer_hint. */
2956 return relay_send_command_from_edge(0, circ,
2957 RELAY_COMMAND_PADDING_NEGOTIATED,
2958 (void*)cell.payload,
2959 (size_t)len, NULL) == 0;
2960}
2961
2962/**
2963 * Parse and react to a padding_negotiate cell.
2964 *
2965 * This is called at the middle node upon receipt of the client's choice of
2966 * state machine, so that it can use the requested state machine index, if
2967 * it is available.
2968 *
2969 * Returns -1 on error, 0 on success.
2970 */
2973{
2974 int retval = 0;
2975 /* Should we send back a STOP cell? */
2976 bool respond_with_stop = true;
2977 circpad_negotiate_t *negotiate;
2978
2979 if (CIRCUIT_IS_ORIGIN(circ)) {
2980 log_fn(LOG_PROTOCOL_WARN, LD_CIRC,
2981 "Padding negotiate cell unsupported at origin (circuit %u)",
2982 TO_ORIGIN_CIRCUIT(circ)->global_identifier);
2983 return -1;
2984 }
2985
2986 if (circpad_negotiate_parse(&negotiate, cell->payload+RELAY_HEADER_SIZE,
2988 log_fn(LOG_PROTOCOL_WARN, LD_CIRC,
2989 "Received malformed PADDING_NEGOTIATE cell; dropping.");
2990 return -1;
2991 }
2992
2993 if (negotiate->command == CIRCPAD_COMMAND_STOP) {
2994 /* Free the machine corresponding to this machine type */
2996 negotiate->machine_type,
2997 negotiate->machine_ctr)) {
2998 log_info(LD_CIRC, "Received STOP command for machine %u, ctr %u",
2999 negotiate->machine_type, negotiate->machine_ctr);
3000 goto done;
3001 }
3002
3003 /* If we reached this point we received a STOP command from an old or
3004 unknown machine. Don't reply with our own STOP since there is no one to
3005 handle it on the other end */
3006 respond_with_stop = false;
3007
3008 if (negotiate->machine_ctr <= circ->padding_machine_ctr) {
3009 log_info(LD_CIRC, "Received STOP command for old machine %u, ctr %u",
3010 negotiate->machine_type, negotiate->machine_ctr);
3011 goto done;
3012
3013 } else {
3014 log_fn(LOG_PROTOCOL_WARN, LD_CIRC,
3015 "Received circuit padding stop command for unknown machine.");
3016 goto err;
3017 }
3018 } else if (negotiate->command == CIRCPAD_COMMAND_START) {
3020 const circpad_machine_spec_t *, m) {
3021 if (m->machine_num == negotiate->machine_type) {
3022 circpad_setup_machine_on_circ(circ, m);
3023 if (negotiate->machine_ctr &&
3024 circ->padding_machine_ctr != negotiate->machine_ctr) {
3025 log_fn(LOG_PROTOCOL_WARN, LD_CIRC,
3026 "Client and relay have different counts for padding machines: "
3027 "%u vs %u", circ->padding_machine_ctr, negotiate->machine_ctr);
3028 }
3030 goto done;
3031 }
3032 } SMARTLIST_FOREACH_END(m);
3033 }
3034
3035 err:
3036 retval = -1;
3037
3038 done:
3039 if (respond_with_stop) {
3040 circpad_padding_negotiated(circ, negotiate->machine_type,
3041 negotiate->command,
3042 (retval == 0) ? CIRCPAD_RESPONSE_OK : CIRCPAD_RESPONSE_ERR,
3043 negotiate->machine_ctr);
3044 }
3045
3046 circpad_negotiate_free(negotiate);
3047
3048 return retval;
3049}
3050
3051/**
3052 * Parse and react to a padding_negotiated cell.
3053 *
3054 * This is called at the origin upon receipt of the middle's response
3055 * to our choice of state machine.
3056 *
3057 * Returns -1 on error, 0 on success.
3058 */
3061 crypt_path_t *layer_hint)
3062{
3063 circpad_negotiated_t *negotiated;
3064
3065 if (!CIRCUIT_IS_ORIGIN(circ)) {
3066 log_fn(LOG_PROTOCOL_WARN, LD_CIRC,
3067 "Padding negotiated cell unsupported at non-origin.");
3068 return -1;
3069 }
3070
3071 /* Verify this came from the expected hop */
3072 if (!circpad_padding_is_from_expected_hop(circ, layer_hint)) {
3073 log_fn(LOG_PROTOCOL_WARN, LD_CIRC,
3074 "Padding negotiated cell from wrong hop on circuit %u",
3075 TO_ORIGIN_CIRCUIT(circ)->global_identifier);
3076 return -1;
3077 }
3078
3079 if (circpad_negotiated_parse(&negotiated, cell->payload+RELAY_HEADER_SIZE,
3081 log_fn(LOG_PROTOCOL_WARN, LD_CIRC,
3082 "Received malformed PADDING_NEGOTIATED cell on circuit %u; "
3083 "dropping.", TO_ORIGIN_CIRCUIT(circ)->global_identifier);
3084 return -1;
3085 }
3086
3087 if (negotiated->command == CIRCPAD_COMMAND_STOP) {
3088 log_info(LD_CIRC,
3089 "Received STOP command on PADDING_NEGOTIATED for circuit %u",
3090 TO_ORIGIN_CIRCUIT(circ)->global_identifier);
3091 /* There may not be a padding_info here if we shut down the
3092 * machine in circpad_shutdown_old_machines(). Or, if
3093 * circpad_add_matching_matchines() added a new machine,
3094 * there may be a padding_machine for a different machine num
3095 * than this response. */
3096 free_circ_machineinfos_with_machine_num(circ, negotiated->machine_type,
3097 negotiated->machine_ctr);
3098 } else if (negotiated->command == CIRCPAD_COMMAND_START &&
3099 negotiated->response == CIRCPAD_RESPONSE_ERR) {
3100 // This can still happen due to consensus drift.. free the machines
3101 // and be sad
3102 if (free_circ_machineinfos_with_machine_num(circ, negotiated->machine_type,
3103 negotiated->machine_ctr)) {
3104 // Only fail if a machine was there and matched the error cell
3105 TO_ORIGIN_CIRCUIT(circ)->padding_negotiation_failed = 1;
3106 log_fn(LOG_PROTOCOL_WARN, LD_CIRC,
3107 "Middle node did not accept our padding request on circuit "
3108 "%u (%d)",
3109 TO_ORIGIN_CIRCUIT(circ)->global_identifier,
3110 circ->purpose);
3111 }
3112 }
3113
3114 circpad_negotiated_free(negotiated);
3115 return 0;
3116}
3117
3118/** Free memory allocated by this machine spec. */
3119STATIC void
3121{
3122 if (!m) return;
3123
3124 tor_free(m->states);
3125 tor_free(m);
3126}
3127
3128/** Free all memory allocated by the circuitpadding subsystem. */
3129void
3131{
3135 machine_spec_free(m);
3136 } SMARTLIST_FOREACH_END(m);
3137 smartlist_free(origin_padding_machines);
3138 }
3142 machine_spec_free(m);
3143 } SMARTLIST_FOREACH_END(m);
3144 smartlist_free(relay_padding_machines);
3145 }
3146}
3147
3148/* Serialization */
3149// TODO: Should we use keyword=value here? Are there helpers for that?
3150#if 0
3151static void
3152circpad_state_serialize(const circpad_state_t *state,
3153 smartlist_t *chunks)
3154{
3155 smartlist_add_asprintf(chunks, " %u", state->histogram[0]);
3156 for (int i = 1; i < state->histogram_len; i++) {
3157 smartlist_add_asprintf(chunks, ",%u",
3158 state->histogram[i]);
3159 }
3160
3161 smartlist_add_asprintf(chunks, " 0x%x",
3162 state->transition_cancel_events);
3163
3164 for (int i = 0; i < CIRCPAD_NUM_STATES; i++) {
3165 smartlist_add_asprintf(chunks, ",0x%x",
3166 state->transition_events[i]);
3167 }
3168
3169 smartlist_add_asprintf(chunks, " %u %u",
3170 state->use_rtt_estimate,
3171 state->token_removal);
3172}
3173
3174char *
3176{
3177 smartlist_t *chunks = smartlist_new();
3178 char *out;
3179 (void)machine;
3180
3181 circpad_state_serialize(&machine->start, chunks);
3182 circpad_state_serialize(&machine->gap, chunks);
3183 circpad_state_serialize(&machine->burst, chunks);
3184
3185 out = smartlist_join_strings(chunks, "", 0, NULL);
3186
3187 SMARTLIST_FOREACH(chunks, char *, cp, tor_free(cp));
3188 smartlist_free(chunks);
3189 return out;
3190}
3191
3192// XXX: Writeme
3194circpad_string_to_machine(const char *str)
3195{
3196 (void)str;
3197 return NULL;
3198}
3199
3200#endif /* 0 */
time_t approx_time(void)
Definition: approx_time.c:32
Fixed-size cell structure.
Header file for channel.c.
Base circuit structure.
origin_circuit_t * TO_ORIGIN_CIRCUIT(circuit_t *x)
Definition: circuitlist.c:185
int circuit_get_cpath_len(origin_circuit_t *circ)
Definition: circuitlist.c:2035
int circuit_get_cpath_opened_len(const origin_circuit_t *circ)
Definition: circuitlist.c:2051
void assert_circuit_ok(const circuit_t *c)
Definition: circuitlist.c:2809
or_circuit_t * TO_OR_CIRCUIT(circuit_t *x)
Definition: circuitlist.c:173
crypt_path_t * circuit_get_cpath_hop(origin_circuit_t *circ, int hopnum)
Definition: circuitlist.c:2071
const char * circuit_purpose_to_string(uint8_t purpose)
Definition: circuitlist.c:929
Header file for circuitlist.c.
#define CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT
Definition: circuitlist.h:93
#define CIRCUIT_PURPOSE_PATH_BIAS_TESTING
Definition: circuitlist.h:123
#define CIRCUIT_STATE_OPEN
Definition: circuitlist.h:32
#define CIRCUIT_IS_ORIGIN(c)
Definition: circuitlist.h:154
#define CIRCUIT_PURPOSE_C_CIRCUIT_PADDING
Definition: circuitlist.h:95
STATIC const circpad_state_t * circpad_machine_current_state(const circpad_machine_runtime_t *mi)
static bool padding_machine_state_is_valid(const circpad_state_t *state)
static void circpad_send_padding_callback(tor_timer_t *timer, void *args, const struct monotime_t *time)
static void circpad_estimate_circ_rtt_on_send(circuit_t *circ, circpad_machine_runtime_t *mi)
void circpad_machines_init(void)
STATIC circpad_delay_t histogram_get_bin_upper_bound(const circpad_machine_runtime_t *mi, circpad_hist_index_t bin)
void circpad_cell_event_nonpadding_received(circuit_t *on_circ)
void circpad_machine_event_circ_added_hop(origin_circuit_t *on_circ)
static void circpad_circuit_machineinfo_free_idx(circuit_t *circ, int idx)
void circpad_new_consensus_params(const networkstatus_t *ns)
circpad_decision_t circpad_internal_event_infinity(circpad_machine_runtime_t *mi)
static bool padding_machine_is_valid(const circpad_machine_spec_t *machine)
STATIC void machine_spec_free_(circpad_machine_spec_t *m)
STATIC bool circpad_machine_reached_padding_limit(circpad_machine_runtime_t *mi)
void circpad_circuit_free_all_machineinfos(circuit_t *circ)
static int free_circ_machineinfos_with_machine_num(circuit_t *circ, int machine_num, uint32_t machine_ctr)
circpad_decision_t circpad_send_padding_cell_for_callback(circpad_machine_runtime_t *mi)
STATIC const node_t * circuit_get_nth_node(origin_circuit_t *circ, int hop)
static circpad_decision_t check_machine_token_supply(circpad_machine_runtime_t *mi)
static double circpad_distribution_sample(circpad_distribution_t dist)
STATIC circpad_machine_runtime_t * circpad_circuit_machineinfo_new(circuit_t *on_circ, int machine_index)
#define FOR_EACH_CIRCUIT_MACHINE_BEGIN(loop_var)
static void circpad_machine_count_padding_sent(circpad_machine_runtime_t *mi)
static bool circpad_machine_conditions_keep(origin_circuit_t *circ, const circpad_machine_spec_t *machine)
static void circpad_machine_update_state_length_for_nonpadding(circpad_machine_runtime_t *mi)
void circpad_deliver_sent_relay_cell_events(circuit_t *circ, uint8_t relay_command)
bool circpad_padding_negotiated(circuit_t *circ, circpad_machine_num_t machine, uint8_t command, uint8_t response, uint32_t machine_ctr)
void circpad_deliver_unrecognized_cell_events(circuit_t *circ, cell_direction_t dir)
static void circpad_choose_state_length(circpad_machine_runtime_t *mi)
STATIC void circpad_machine_setup_tokens(circpad_machine_runtime_t *mi)
static circpad_hist_index_t circpad_machine_first_lower_index(const circpad_machine_runtime_t *mi, circpad_delay_t target_bin_usec)
static void circpad_machine_count_nonpadding_sent(circpad_machine_runtime_t *mi)
void circpad_cell_event_padding_received(circuit_t *on_circ)
STATIC circpad_hist_index_t circpad_histogram_usec_to_bin(const circpad_machine_runtime_t *mi, circpad_delay_t usec)
static uint64_t circpad_global_padding_sent
void circpad_free_all(void)
signed_error_t circpad_handle_padding_negotiated(circuit_t *circ, cell_t *cell, crypt_path_t *layer_hint)
STATIC void circpad_machine_remove_higher_token(circpad_machine_runtime_t *mi, circpad_delay_t target_bin_usec)
static circpad_delay_t circpad_distribution_sample_iat_delay(const circpad_state_t *state, circpad_delay_t delay_shift)
STATIC signed_error_t circpad_send_command_to_hop(origin_circuit_t *circ, uint8_t hopnum, uint8_t relay_command, const uint8_t *payload, ssize_t payload_len)
void circpad_machines_free(void)
void circpad_machine_event_circ_purpose_changed(origin_circuit_t *circ)
void circpad_machine_event_circ_has_no_streams(origin_circuit_t *circ)
STATIC void circpad_machine_remove_closest_token(circpad_machine_runtime_t *mi, circpad_delay_t target_bin_usec, bool use_usec)
signed_error_t circpad_handle_padding_negotiate(circuit_t *circ, cell_t *cell)
int circpad_marked_circuit_for_padding(circuit_t *circ, int reason)
bool circpad_padding_is_from_expected_hop(circuit_t *circ, crypt_path_t *from_hop)
static circpad_hist_index_t circpad_machine_first_higher_index(const circpad_machine_runtime_t *mi, circpad_delay_t target_bin_usec)
static void circpad_estimate_circ_rtt_on_received(circuit_t *circ, circpad_machine_runtime_t *mi)
void circpad_machine_event_circ_has_no_relay_early(origin_circuit_t *circ)
void circpad_deliver_recognized_relay_cell_events(circuit_t *circ, uint8_t relay_command, crypt_path_t *layer_hint)
void circpad_machine_states_init(circpad_machine_spec_t *machine, circpad_statenum_t num_states)
STATIC void circpad_add_matching_machines(origin_circuit_t *on_circ, smartlist_t *machines_sl)
static bool circpad_is_padding_allowed(void)
STATIC smartlist_t * relay_padding_machines
void circpad_machine_event_circ_has_streams(origin_circuit_t *circ)
static bool circpad_machine_conditions_apply(origin_circuit_t *circ, const circpad_machine_spec_t *machine)
static bool circpad_node_supports_padding(const node_t *node)
STATIC circpad_delay_t circpad_histogram_bin_to_usec(const circpad_machine_runtime_t *mi, circpad_hist_index_t bin)
STATIC void circpad_machine_remove_lower_token(circpad_machine_runtime_t *mi, circpad_delay_t target_bin_usec)
static circpad_circuit_state_t circpad_circuit_state(origin_circuit_t *circ)
circpad_purpose_mask_t circpad_circ_purpose_to_mask(uint8_t circ_purpose)
circpad_decision_t circpad_machine_schedule_padding(circpad_machine_runtime_t *mi)
static int circpad_is_token_removal_supported(circpad_machine_runtime_t *mi)
STATIC void circpad_machine_remove_token(circpad_machine_runtime_t *mi)
STATIC smartlist_t * origin_padding_machines
static uint8_t circpad_padding_disabled
STATIC circpad_delay_t circpad_machine_sample_delay(circpad_machine_runtime_t *mi)
static void circpad_machine_spec_transitioned_to_end(circpad_machine_runtime_t *mi)
static circpad_delay_t circpad_get_histogram_bin_midpoint(const circpad_machine_runtime_t *mi, int bin_index)
signed_error_t circpad_negotiate_padding(origin_circuit_t *circ, circpad_machine_num_t machine, uint8_t target_hopnum, uint8_t command, uint32_t machine_ctr)
void circpad_cell_event_padding_sent(circuit_t *on_circ)
static void circpad_shutdown_old_machines(origin_circuit_t *on_circ)
#define FOR_EACH_ACTIVE_CIRCUIT_MACHINE_BEGIN(loop_var, circ)
circpad_decision_t circpad_internal_event_bins_empty(circpad_machine_runtime_t *mi)
circpad_decision_t circpad_internal_event_state_length_up(circpad_machine_runtime_t *mi)
circpad_decision_t circpad_machine_spec_transition(circpad_machine_runtime_t *mi, circpad_event_t event)
void circpad_cell_event_nonpadding_sent(circuit_t *on_circ)
void circpad_machine_event_circ_built(origin_circuit_t *circ)
int circpad_check_received_cell(cell_t *cell, circuit_t *circ, crypt_path_t *layer_hint, const relay_header_t *rh)
static void circpad_machine_remove_exact(circpad_machine_runtime_t *mi, circpad_delay_t target_bin_usec)
static bool circpad_circuit_supports_padding(origin_circuit_t *circ, int target_hopnum)
Header file for circuitpadding.c.
circpad_circuit_state_t
int8_t circpad_hist_index_t
#define CIRCPAD_DELAY_INFINITE
circpad_event_t
int signed_error_t
#define CIRCPAD_GET_MACHINE(machineinfo)
uint64_t circpad_time_t
uint8_t circpad_machine_num_t
#define CIRCPAD_STATE_CANCEL
#define CIRCPAD_INFINITY_BIN(mi)
uint32_t circpad_hist_token_t
#define CIRCPAD_STATE_START
circpad_decision_t
uint16_t circpad_statenum_t
uint32_t circpad_purpose_mask_t
#define CIRCPAD_STATE_GAP
char * circpad_machine_spec_to_string(const circpad_machine_spec_t *machine)
#define CIRCPAD_DELAY_MAX_SECS
#define CIRCPAD_STATE_IGNORE
#define CIRCPAD_MAX_MACHINE_STATES
#define CIRCPAD_STATE_BURST
#define CIRCPAD_STATE_END
uint32_t circpad_delay_t
#define CIRCPAD_PURPOSE_ALL
@ CIRCPAD_TOKEN_REMOVAL_LOWER
@ CIRCPAD_TOKEN_REMOVAL_HIGHER
@ CIRCPAD_TOKEN_REMOVAL_NONE
@ CIRCPAD_TOKEN_REMOVAL_CLOSEST_USEC
@ CIRCPAD_TOKEN_REMOVAL_EXACT
@ CIRCPAD_TOKEN_REMOVAL_CLOSEST
void circpad_machine_client_hide_rend_circuits(smartlist_t *machines_sl)
void circpad_machine_client_hide_intro_circuits(smartlist_t *machines_sl)
void circpad_machine_relay_hide_intro_circuits(smartlist_t *machines_sl)
void circpad_machine_relay_hide_rend_circuits(smartlist_t *machines_sl)
Header file for circuitpadding_machines.c.
void circuit_read_valid_data(origin_circuit_t *circ, uint16_t relay_body_len)
Definition: circuituse.c:3197
void circuit_change_purpose(circuit_t *circ, uint8_t new_purpose)
Definition: circuituse.c:3095
Header file for circuituse.c.
#define MAX(a, b)
Definition: cmp.h:22
uint64_t monotime_absolute_usec(void)
Definition: compat_time.c:804
Functions and types for monotonic times.
const or_options_t * get_options(void)
Definition: config.c:944
tor_cmdline_mode_t command
Definition: config.c:2468
Header file for config.c.
void conflux_sync_circ_fields(conflux_t *cfx, origin_circuit_t *ref_circ)
Definition: conflux_util.c:295
Header file for conflux_util.c.
Path structures for origin circuits.
Common functions for using (pseudo-)random number generators.
uint64_t crypto_fast_rng_uint64_range(crypto_fast_rng_t *rng, uint64_t min, uint64_t max)
crypto_fast_rng_t * get_thread_fast_rng(void)
uint64_t crypto_fast_rng_get_uint64(crypto_fast_rng_t *rng, uint64_t limit)
Extend-info structure.
int64_t clamp_double_to_int64(double number)
Definition: fp.c:61
int64_t tor_llround(double d)
Definition: fp.c:46
Header for fp.c.
#define log_fn(severity, domain, args,...)
Definition: log.h:283
#define log_fn_ratelim(ratelim, severity, domain, args,...)
Definition: log.h:288
#define LOG_DEBUG
Definition: log.h:42
#define LD_BUG
Definition: log.h:86
#define LOG_NOTICE
Definition: log.h:50
#define LD_CIRC
Definition: log.h:82
#define LOG_WARN
Definition: log.h:53
#define LOG_INFO
Definition: log.h:45
#define tor_free(p)
Definition: malloc.h:56
bool is_participating_on_network(void)
Definition: netstatus.c:110
Header for netstatus.c.
int32_t networkstatus_get_param(const networkstatus_t *ns, const char *param_name, int32_t default_val, int32_t min_val, int32_t max_val)
Header file for networkstatus.c.
Node information structure.
const node_t * node_get_by_id(const char *identity_digest)
Definition: nodelist.c:226
Header file for nodelist.c.
Master header file for Tor-specific functionality.
#define CELL_PAYLOAD_SIZE
Definition: or.h:465
#define TO_CIRCUIT(x)
Definition: or.h:848
#define RELAY_HEADER_SIZE
Definition: or.h:492
cell_direction_t
Definition: or.h:375
@ CELL_DIRECTION_OUT
Definition: or.h:377
@ CELL_DIRECTION_IN
Definition: or.h:376
Origin circuit structure.
Header for prob_distr.c.
Header file for relay.c.
Header for relay_crypto.c.
void rep_hist_padding_count_write(padding_type_t type)
Definition: rephist.c:2816
void rep_hist_padding_count_read(padding_type_t type)
Definition: rephist.c:2846
Header file for rephist.c.
@ PADDING_TYPE_DROP
Definition: rephist.h:150
Routerstatus (consensus entry) structure.
void smartlist_add_asprintf(struct smartlist_t *sl, const char *pattern,...)
Definition: smartlist.c:36
char * smartlist_join_strings(smartlist_t *sl, const char *join, int terminate, size_t *len_out)
Definition: smartlist.c:279
smartlist_t * smartlist_new(void)
void smartlist_add(smartlist_t *sl, void *element)
#define SMARTLIST_FOREACH_BEGIN(sl, type, var)
#define SMARTLIST_FOREACH(sl, type, var, cmd)
#define SMARTLIST_FOREACH_REVERSE_BEGIN(sl, type, var)
Definition: cell_st.h:17
uint8_t payload[CELL_PAYLOAD_SIZE]
Definition: cell_st.h:21
uint8_t command
Definition: cell_st.h:19
uint64_t global_identifier
Definition: channel.h:197
circpad_purpose_mask_t apply_purpose_mask
circpad_purpose_mask_t keep_purpose_mask
circpad_circuit_state_t apply_state_mask
circpad_circuit_state_t keep_state_mask
struct circuit_t * on_circ
circpad_hist_token_t * histogram
circpad_time_t padding_scheduled_at_usec
circpad_time_t last_received_time_usec
circpad_statenum_t current_state
circpad_hist_index_t histogram_len
circpad_delay_t rtt_estimate_usec
circpad_hist_index_t chosen_bin
circpad_statenum_t num_states
circpad_machine_num_t machine_num
circpad_state_t * states
circpad_machine_conditions_t conditions
circpad_distribution_t iat_dist
circpad_hist_token_t histogram[CIRCPAD_MAX_HISTOGRAM_LEN]
unsigned use_rtt_estimate
uint32_t histogram_total_tokens
circpad_distribution_t length_dist
circpad_statenum_t next_state[CIRCPAD_NUM_EVENTS]
circpad_removal_t token_removal
circpad_hist_index_t histogram_len
unsigned length_includes_nonpadding
uint16_t start_length
uint8_t state
Definition: circuit_st.h:111
time_t timestamp_dirty
Definition: circuit_st.h:188
struct circpad_machine_runtime_t * padding_info[CIRCPAD_MAX_MACHINES]
Definition: circuit_st.h:241
uint16_t marked_for_close
Definition: circuit_st.h:190
struct conflux_t * conflux
Definition: circuit_st.h:263
const struct circpad_machine_spec_t * padding_machine[CIRCPAD_MAX_MACHINES]
Definition: circuit_st.h:230
uint8_t purpose
Definition: circuit_st.h:112
uint32_t padding_machine_ctr
Definition: circuit_st.h:247
channel_t * n_chan
Definition: circuit_st.h:70
circid_t n_circ_id
Definition: circuit_st.h:79
uint8_t state
Definition: crypt_path_st.h:73
extend_info_t * extend_info
Definition: crypt_path_st.h:66
char identity_digest[DIGEST_LEN]
Definition: node_st.h:34
struct routerset_t * HSLayer2Nodes
struct routerset_t * HSLayer3Nodes
edge_connection_t * p_streams
unsigned int remaining_relay_early_cells
unsigned int has_opened
unsigned int supports_hs_setup_padding
Definition: or.h:738
uint16_t length
Definition: or.h:531
uint8_t command
Definition: or.h:527
protover_summary_flags_t pv
#define STATIC
Definition: testsupport.h:32
#define MOCK_IMPL(rv, funcname, arglist)
Definition: testsupport.h:133
Definitions for timing-related constants.
#define TOR_USEC_PER_SEC
Definition: time.h:17
void timer_set_cb(tor_timer_t *t, timer_cb_fn_t cb, void *arg)
Definition: timers.c:276
void timer_schedule(tor_timer_t *t, const struct timeval *tv)
Definition: timers.c:301
tor_timer_t * timer_new(timer_cb_fn_t cb, void *arg)
Definition: timers.c:250
void timer_disable(tor_timer_t *t)
Definition: timers.c:326
#define tor_assert_nonfatal_unreached()
Definition: util_bug.h:177
#define tor_assert(expr)
Definition: util_bug.h:103
#define tor_fragile_assert()
Definition: util_bug.h:278
#define IF_BUG_ONCE(cond)
Definition: util_bug.h:254