commit 857c54ca038baf0881ce6859dbdb2c3446f54c50 Author: Mike Perry <mikeperry-git@torproject.org> Date: Thu May 16 19:42:45 2019 +0000 Refactor rend machines, stage 2/2: Move histogram code. Comment clarifications now that the code is seperated. It's the same code, but its doing this for different reasons on each side. --- src/core/or/circuitpadding_machines.c | 103 +++++++++++++++++++++++----------- 1 file changed, 70 insertions(+), 33 deletions(-) diff --git a/src/core/or/circuitpadding_machines.c b/src/core/or/circuitpadding_machines.c index 5350e6e86..75d2614ac 100644 --- a/src/core/or/circuitpadding_machines.c +++ b/src/core/or/circuitpadding_machines.c @@ -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);