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/* Copyright (c) 2001 Matej Pfajfar.
* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2012, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file onion.c
* \brief Functions to queue create cells, and handle onionskin
* parsing and creation.
**/
#include "or.h"
#include "circuitlist.h"
#include "config.h"
#include "onion.h"
#include "rephist.h"
/** Type for a linked list of circuits that are waiting for a free CPU worker
* to process a waiting onion handshake. */
typedef struct onion_queue_t {
or_circuit_t *circ;
char *onionskin;
time_t when_added;
struct onion_queue_t *next;
} onion_queue_t;
/** 5 seconds on the onion queue til we just send back a destroy */
#define ONIONQUEUE_WAIT_CUTOFF 5
/** First and last elements in the linked list of circuits waiting for CPU
* workers, or NULL if the list is empty.
* @{ */
static onion_queue_t *ol_list=NULL;
static onion_queue_t *ol_tail=NULL;
/**@}*/
/** Length of ol_list */
static int ol_length=0;
/** Add <b>circ</b> to the end of ol_list and return 0, except
* if ol_list is too long, in which case do nothing and return -1.
*/
int
onion_pending_add(or_circuit_t *circ, char *onionskin)
{
onion_queue_t *tmp;
time_t now = time(NULL);
tmp = tor_malloc_zero(sizeof(onion_queue_t));
tmp->circ = circ;
tmp->onionskin = onionskin;
tmp->when_added = now;
if (!ol_tail) {
tor_assert(!ol_list);
tor_assert(!ol_length);
ol_list = tmp;
ol_tail = tmp;
ol_length++;
return 0;
}
tor_assert(ol_list);
tor_assert(!ol_tail->next);
if (ol_length >= get_options()->MaxOnionsPending) {
#define WARN_TOO_MANY_CIRC_CREATIONS_INTERVAL (60)
static ratelim_t last_warned =
RATELIM_INIT(WARN_TOO_MANY_CIRC_CREATIONS_INTERVAL);
char *m;
if ((m = rate_limit_log(&last_warned, approx_time()))) {
log_warn(LD_GENERAL,
"Your computer is too slow to handle this many circuit "
"creation requests! Please consider using the "
"MaxAdvertisedBandwidth config option or choosing a more "
"restricted exit policy.%s",m);
tor_free(m);
}
tor_free(tmp);
return -1;
}
ol_length++;
ol_tail->next = tmp;
ol_tail = tmp;
while ((int)(now - ol_list->when_added) >= ONIONQUEUE_WAIT_CUTOFF) {
/* cull elderly requests. */
circ = ol_list->circ;
onion_pending_remove(ol_list->circ);
log_info(LD_CIRC,
"Circuit create request is too old; canceling due to overload.");
circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_RESOURCELIMIT);
}
return 0;
}
/** Remove the first item from ol_list and return it, or return
* NULL if the list is empty.
*/
or_circuit_t *
onion_next_task(char **onionskin_out)
{
or_circuit_t *circ;
if (!ol_list)
return NULL; /* no onions pending, we're done */
tor_assert(ol_list->circ);
tor_assert(ol_list->circ->p_chan); /* make sure it's still valid */
tor_assert(ol_length > 0);
circ = ol_list->circ;
*onionskin_out = ol_list->onionskin;
ol_list->onionskin = NULL; /* prevent free. */
onion_pending_remove(ol_list->circ);
return circ;
}
/** Go through ol_list, find the onion_queue_t element which points to
* circ, remove and free that element. Leave circ itself alone.
*/
void
onion_pending_remove(or_circuit_t *circ)
{
onion_queue_t *tmpo, *victim;
if (!ol_list)
return; /* nothing here. */
/* first check to see if it's the first entry */
tmpo = ol_list;
if (tmpo->circ == circ) {
/* it's the first one. remove it from the list. */
ol_list = tmpo->next;
if (!ol_list)
ol_tail = NULL;
ol_length--;
victim = tmpo;
} else { /* we need to hunt through the rest of the list */
for ( ;tmpo->next && tmpo->next->circ != circ; tmpo=tmpo->next) ;
if (!tmpo->next) {
log_debug(LD_GENERAL,
"circ (p_circ_id %d) not in list, probably at cpuworker.",
circ->p_circ_id);
return;
}
/* now we know tmpo->next->circ == circ */
victim = tmpo->next;
tmpo->next = victim->next;
if (ol_tail == victim)
ol_tail = tmpo;
ol_length--;
}
/* now victim points to the element that needs to be removed */
tor_free(victim->onionskin);
tor_free(victim);
}
/** Remove all circuits from the pending list. Called from tor_free_all. */
void
clear_pending_onions(void)
{
while (ol_list) {
onion_queue_t *victim = ol_list;
ol_list = victim->next;
tor_free(victim->onionskin);
tor_free(victim);
}
ol_list = ol_tail = NULL;
ol_length = 0;
}
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