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Refactor rend machines, stage 2/2: Move histogram code.

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Comment clarifications now that the code is seperated. It's the same code, but
its doing this for different reasons on each side.
This commit is contained in:
Mike Perry 2019-05-16 19:42:45 +00:00
parent 0cba53c6ed
commit 857c54ca03
1 changed files with 70 additions and 33 deletions
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103
src/core/or/circuitpadding_machines.c
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@ -255,35 +255,6 @@ circpad_machine_relay_hide_intro_circuits(smartlist_t *machines_sl)
/************************** Rendezvous-circuit machine ***********************/
/* Setup the obf state of the machine that hides client-side rend
* circuits. */
static void
setup_obf_state_for_hiding_rend_circuits(circpad_state_t *obf_state)
{
/* Don't use a token removal strategy since we don't want to use monotime
functions. We want this machine to be light. */
obf_state->token_removal = CIRCPAD_TOKEN_REMOVAL_NONE;
/* Instead, to control the volume of padding (we just want to send a single
* padding cell) we will use a static state length. We just want one token,
* since we want to make the following pattern:
* [PADDING_NEGOTIATE] -> [DROP] -> PADDING_NEGOTIATED -> DROP */
obf_state->length_dist.type = CIRCPAD_DIST_UNIFORM;
obf_state->length_dist.param1 = 1;
obf_state->length_dist.param2 = 2;
/* Histogram is: (0 msecs, 50 msecs, infinity). We want this to be fast so
* that the incoming PADDING_NEGOTIATED cell always arrives after the
* outgoing [DROP]. */
obf_state->histogram_len = 2;
obf_state->histogram_edges[0] = 0;
obf_state->histogram_edges[1] = 1000;
/* dummy amount of tokens. they don't matter. we rely on state length. */
obf_state->histogram[0] = 1;
obf_state->histogram_total_tokens = 1;
}
/** Create a client-side padding machine that aims to hide rendezvous
* circuits.*/
void
@ -356,8 +327,41 @@ circpad_machine_client_hide_rend_circuits(smartlist_t *machines_sl)
client_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
next_state[CIRCPAD_EVENT_LENGTH_COUNT] = CIRCPAD_STATE_END;
setup_obf_state_for_hiding_rend_circuits(
&client_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP]);
/* Don't use a token removal strategy since we don't want to use monotime
* functions and we want to avoid mallocing histogram copies. We want
* this machine to be light. */
client_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
token_removal = CIRCPAD_TOKEN_REMOVAL_NONE;
/* Instead, to control the volume of padding (we just want to send a single
* padding cell) we will use a static state length. We just want one token,
* since we want to make the following pattern:
* [PADDING_NEGOTIATE] -> [DROP] -> PADDING_NEGOTIATED -> DROP */
client_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
length_dist.type = CIRCPAD_DIST_UNIFORM;
client_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
length_dist.param1 = 1;
client_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
length_dist.param2 = 2; // rand(1,2) is always 1
/* Histogram is: (0 msecs, 1 msec, infinity). We want this to be fast so
* that we send our outgoing [DROP] before the PADDING_NEGOTIATED comes
* back from the relay side. */
client_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
histogram_len = 2;
client_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
histogram_edges[0] = 0;
client_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
histogram_edges[1] = 1000;
/* We want a 100% probability of choosing an inter-packet delay of
* between 0 and 1ms. Since we don't use token removal,
* the number of tokens does not matter. (And also, state_length
* governs how many packets we send). */
client_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
histogram[0] = 1;
client_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
histogram_total_tokens = 1;
/* Register the machine */
client_machine->machine_num = smartlist_len(machines_sl);
@ -408,8 +412,41 @@ circpad_machine_relay_hide_rend_circuits(smartlist_t *machines_sl)
relay_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
next_state[CIRCPAD_EVENT_LENGTH_COUNT] = CIRCPAD_STATE_END;
setup_obf_state_for_hiding_rend_circuits(
&relay_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP]);
/* Don't use a token removal strategy since we don't want to use monotime
* functions and we want to avoid mallocing histogram copies. We want
* this machine to be light. */
relay_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
token_removal = CIRCPAD_TOKEN_REMOVAL_NONE;
/* Instead, to control the volume of padding (we just want to send a single
* padding cell) we will use a static state length. We just want one token,
* since we want to make the following pattern:
* [PADDING_NEGOTIATE] -> [DROP] -> PADDING_NEGOTIATED -> DROP */
relay_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
length_dist.type = CIRCPAD_DIST_UNIFORM;
relay_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
length_dist.param1 = 1;
relay_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
length_dist.param2 = 2; // rand(1,2) is always 1
/* Histogram is: (0 msecs, 1 msec, infinity). We want this to be fast so
* that the outgoing DROP cell is sent immediately after the
* PADDING_NEGOTIATED. */
relay_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
histogram_len = 2;
relay_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
histogram_edges[0] = 0;
relay_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
histogram_edges[1] = 1000;
/* We want a 100% probability of choosing an inter-packet delay of
* between 0 and 1ms. Since we don't use token removal,
* the number of tokens does not matter. (And also, state_length
* governs how many packets we send). */
relay_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
histogram[0] = 1;
relay_machine->states[CIRCPAD_STATE_OBFUSCATE_CIRC_SETUP].
histogram_total_tokens = 1;
/* Register the machine */
relay_machine->machine_num = smartlist_len(machines_sl);