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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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