Commit 857c54ca authored by Mike Perry's avatar Mike Perry
Browse files

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.
parent 0cba53c6

src/core/or/circuitpadding_machines.c

+70 −33
Original line number Diff line number Diff line
@@ -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);