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circpad: Machines MUST have strictly increasing histogram edges.
Add a basic validation function for the histograms. It can be a building block for the future
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@ -494,12 +494,13 @@ circpad_machine_sample_delay(circpad_machine_state_t *mi)
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* function below samples from [bin_start, bin_end) */
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bin_end = circpad_histogram_bin_to_usec(mi, curr_bin+1);
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// Sample uniformly between histogram[i] to histogram[i+1]-1,
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// but no need to sample if they are the same timeval (aka bin 0 or bin 1).
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if (bin_end <= bin_start+1)
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/* Bin edges are monotonically increasing so this is a bug. Handle it. */
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if (BUG(bin_start > bin_end)) {
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return bin_start;
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else
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return (circpad_delay_t)crypto_rand_uint64_range(bin_start, bin_end);
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}
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/* Sample randomly from within the bin width */
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return (circpad_delay_t)crypto_rand_uint64_range(bin_start, bin_end);
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}
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/**
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@ -2050,16 +2051,92 @@ circpad_setup_machine_on_circ(circuit_t *on_circ,
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on_circ->padding_machine[machine->machine_index] = machine;
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}
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/* These padding machines are only used for tests pending #28634. */
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#ifdef TOR_UNIT_TESTS
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/** Validate a single state of a padding machine */
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static bool
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padding_machine_state_is_valid(const circpad_state_t *state)
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{
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int b;
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uint32_t tokens_count = 0;
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circpad_delay_t prev_bin_edge = 0;
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/* We only validate histograms */
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if (!state->histogram_len) {
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return true;
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}
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/* We need at least two bins in a histogram */
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if (state->histogram_len < 2) {
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log_warn(LD_GENERAL, "You can't have a histogram with less than 2 bins");
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return false;
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}
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/* For each machine state, if it's a histogram, make sure all the
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* histogram edges are well defined (i.e. are strictly monotonic). */
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for (b = 0 ; b < state->histogram_len ; b++) {
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/* Check that histogram edges are strictly increasing. Ignore the first
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* edge since it can be zero. */
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if (prev_bin_edge >= state->histogram_edges[b] && b > 0) {
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log_warn(LD_GENERAL, "Histogram edges are not increasing [%u/%u]",
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prev_bin_edge, state->histogram_edges[b]);
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return false;
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}
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prev_bin_edge = state->histogram_edges[b];
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/* Also count the number of tokens as we go through the histogram states */
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tokens_count += state->histogram[b];
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}
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/* Verify that the total number of tokens is correct */
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if (tokens_count != state->histogram_total_tokens) {
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log_warn(LD_GENERAL, "Histogram token count is wrong [%u/%u]",
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tokens_count, state->histogram_total_tokens);
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return false;
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}
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return true;
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}
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/** Basic validation of padding machine */
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static bool
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padding_machine_is_valid(const circpad_machine_spec_t *machine)
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{
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int i;
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/* Validate the histograms of the padding machine */
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for (i = 0 ; i < machine->num_states ; i++) {
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if (!padding_machine_state_is_valid(&machine->states[i])) {
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return false;
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}
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}
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return true;
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}
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/* Validate and register <b>machine</b> into <b>machine_list</b>. If
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* <b>machine_list</b> is NULL, then just validate. */
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STATIC void
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register_padding_machine(circpad_machine_spec_t *machine,
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smartlist_t *machine_list)
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{
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if (!padding_machine_is_valid(machine)) {
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log_warn(LD_GENERAL, "Machine #%u is invalid. Ignoring.",
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machine->machine_num);
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return;
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}
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if (machine_list) {
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smartlist_add(machine_list, machine);
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}
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}
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/* These padding machines are only used for tests pending #28634. */
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static void
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circpad_circ_client_machine_init(void)
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{
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circpad_machine_spec_t *circ_client_machine
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= tor_malloc_zero(sizeof(circpad_machine_spec_t));
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// XXX: Better conditions for merge.. Or disable this machine in
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// merge?
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circ_client_machine->conditions.min_hops = 2;
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circ_client_machine->conditions.state_mask =
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CIRCPAD_CIRC_BUILDING|CIRCPAD_CIRC_OPENED|CIRCPAD_CIRC_HAS_RELAY_EARLY;
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@ -2091,7 +2168,6 @@ circpad_circ_client_machine_init(void)
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circ_client_machine->states[CIRCPAD_STATE_BURST].token_removal =
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CIRCPAD_TOKEN_REMOVAL_CLOSEST;
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// FIXME: Tune this histogram
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circ_client_machine->states[CIRCPAD_STATE_BURST].histogram_len = 2;
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circ_client_machine->states[CIRCPAD_STATE_BURST].histogram_edges[0]= 500;
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circ_client_machine->states[CIRCPAD_STATE_BURST].histogram_edges[1]= 1000000;
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@ -2105,7 +2181,7 @@ circpad_circ_client_machine_init(void)
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circ_client_machine->states[CIRCPAD_STATE_BURST].histogram_total_tokens = 5;
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circ_client_machine->machine_num = smartlist_len(origin_padding_machines);
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smartlist_add(origin_padding_machines, circ_client_machine);
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register_padding_machine(circ_client_machine, origin_padding_machines);
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}
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static void
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@ -2205,7 +2281,7 @@ circpad_circ_responder_machine_init(void)
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CIRCPAD_TOKEN_REMOVAL_CLOSEST_USEC;
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circ_responder_machine->machine_num = smartlist_len(relay_padding_machines);
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smartlist_add(relay_padding_machines, circ_responder_machine);
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register_padding_machine(circ_responder_machine, relay_padding_machines);
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}
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#endif
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@ -291,7 +291,7 @@ typedef struct circpad_state_t {
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/** The histogram itself: an array of uint16s of tokens, whose
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* widths are exponentially spaced, in microseconds.
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*
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* This array must have histogram_len elements that are (non-strictly)
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* This array must have histogram_len elements that are strictly
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* monotonically increasing. */
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circpad_hist_token_t histogram[CIRCPAD_MAX_HISTOGRAM_LEN];
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/* The histogram bin edges in usec.
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@ -730,6 +730,10 @@ histogram_get_bin_upper_bound(const circpad_machine_state_t *mi,
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#ifdef TOR_UNIT_TESTS
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extern smartlist_t *origin_padding_machines;
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extern smartlist_t *relay_padding_machines;
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STATIC void
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register_padding_machine(circpad_machine_spec_t *machine,
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smartlist_t *machine_list);
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#endif
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#endif
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@ -794,7 +794,7 @@ test_circuitpadding_closest_token_removal(void *arg)
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tt_int_op(client_side->padding_info[0]->current_state, OP_EQ,
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CIRCPAD_STATE_BURST);
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circ_client_machine.states[CIRCPAD_STATE_BURST].histogram_edges[0] = 100;
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circ_client_machine.states[CIRCPAD_STATE_BURST].histogram_edges[1] = 100;
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circ_client_machine.states[CIRCPAD_STATE_BURST].histogram_edges[1] = 101;
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circ_client_machine.states[CIRCPAD_STATE_BURST].histogram_edges[2] = 120;
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mi->padding_scheduled_at_usec = current_time - 102;
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mi->histogram[0] = 0;
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@ -903,7 +903,7 @@ test_circuitpadding_closest_token_removal_usec(void *arg)
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tt_int_op(client_side->padding_info[0]->current_state, OP_EQ,
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CIRCPAD_STATE_BURST);
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circ_client_machine.states[CIRCPAD_STATE_BURST].histogram_edges[0] = 100;
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circ_client_machine.states[CIRCPAD_STATE_BURST].histogram_edges[1] = 100;
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circ_client_machine.states[CIRCPAD_STATE_BURST].histogram_edges[1] = 101;
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circ_client_machine.states[CIRCPAD_STATE_BURST].histogram_edges[2] = 120;
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mi->padding_scheduled_at_usec = current_time - 102;
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mi->histogram[0] = 0;
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@ -1649,7 +1649,7 @@ helper_create_conditional_machine(void)
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ret->states[CIRCPAD_STATE_BURST].histogram_len = 3;
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ret->states[CIRCPAD_STATE_BURST].histogram_edges[0] = 0;
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ret->states[CIRCPAD_STATE_BURST].histogram_edges[1] = 0;
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ret->states[CIRCPAD_STATE_BURST].histogram_edges[1] = 1;
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ret->states[CIRCPAD_STATE_BURST].histogram_edges[2] = 1000000;
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ret->states[CIRCPAD_STATE_BURST].histogram[0] = 6;
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@ -1686,8 +1686,7 @@ helper_create_conditional_machines(void)
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add->conditions.state_mask = CIRCPAD_CIRC_BUILDING|
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CIRCPAD_CIRC_NO_STREAMS|CIRCPAD_CIRC_HAS_RELAY_EARLY;
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add->conditions.purpose_mask = CIRCPAD_PURPOSE_ALL;
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smartlist_add(origin_padding_machines, add);
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register_padding_machine(add, origin_padding_machines);
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add = helper_create_conditional_machine();
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add->machine_num = 3;
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@ -1706,15 +1705,15 @@ helper_create_conditional_machines(void)
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add->conditions.state_mask = CIRCPAD_CIRC_OPENED|
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CIRCPAD_CIRC_STREAMS|CIRCPAD_CIRC_HAS_NO_RELAY_EARLY;
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add->conditions.purpose_mask = CIRCPAD_PURPOSE_ALL;
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smartlist_add(origin_padding_machines, add);
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register_padding_machine(add, origin_padding_machines);
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add = helper_create_conditional_machine();
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add->machine_num = 2;
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smartlist_add(relay_padding_machines, add);
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register_padding_machine(add, relay_padding_machines);
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add = helper_create_conditional_machine();
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add->machine_num = 3;
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smartlist_add(relay_padding_machines, add);
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register_padding_machine(add, relay_padding_machines);
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}
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void
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