/* Copyright (c) 2001 Matej Pfajfar.
* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2016, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file entrynodes.c
* \brief Code to manage our fixed first nodes for various functions.
*
* Entry nodes can be guards (for general use) or bridges (for censorship
* circumvention).
*
* XXXX prop271 This module is in flux, since I'm currently in the middle of
* implementation proposal 271. The module documentation here will describe
* the new algorithm and data structures; the old ones should get removed as
* proposal 271 is completed.
*
* In general, we use entry guards to prevent traffic-sampling attacks:
* if we chose every circuit independently, an adversary controlling
* some fraction of paths on the network would observe a sample of every
* user's traffic. Using guards gives users a chance of not being
* profiled.
*
* The current entry guard selection code is designed to try to avoid
* _ever_ trying every guard on the network, to try to stick to guards
* that we've used before, to handle hostile/broken networks, and
* to behave sanely when the network goes up and down.
*
* Our algorithm works as follows: First, we maintain a SAMPLE of guards
* we've seen in the networkstatus consensus. We maintain this sample
* over time, and store it persistently; it is chosen without reference
* to our configuration or firewall rules. Guards remain in the sample
* as they enter and leave the consensus. We expand this sample as
* needed, up to a maximum size.
*
* As a subset of the sample, we maintain a FILTERED SET of the guards
* that we would be willing to use if we could connect to them. The
* filter removes all the guards that we're excluding because they're
* bridges (or not bridges), because we have restrictive firewall rules,
* because of ExcludeNodes, because we of path bias restrictions,
* because they're absent from the network at present, and so on.
*
* As a subset of the filtered set, we keep a REACHABLE FILTERED SET
* (also called a "usable filtered set") of those guards that we call
* "reachable" or "maybe reachable". A guard is reachable if we've
* connected to it more recently than we've failed. A guard is "maybe
* reachable" if we have never tried to connect to it, or if we
* failed to connect to it so long ago that we no longer think our
* failure means it's down.
*
* As a persistent ordered list whose elements are taken from the
* sampled set, we track a CONFIRMED GUARDS LIST. A guard becomes
* confirmed when we successfully build a circuit through it, and decide
* to use that circuit. We order the guards on this list by the order
* in which they became confirmed.
*
* And as a final group, we have an ordered list of PRIMARY GUARDS,
* whose elements are taken from the filtered set. We prefer
* confirmed guards to non-confirmed guards for this list, and place
* other restrictions on it. The primary guards are the ones that we
* connect to "when nothing is wrong" -- circuits through them can be used
* immediately.
*
* To build circuits, we take a primary guard if possible -- or a
* reachable filtered confirmed guard if no primary guard is possible --
* or a random reachable filtered guard otherwise. If the guard is
* primary, we can use the circuit immediately on success. Otherwise,
* the guard is now "pending" -- we won't use its circuit unless all
* of the circuits we're trying to build through better guards have
* definitely failed.
*
* While we're building circuits, we track a little "guard state" for
* each circuit. We use this to keep track of whether the circuit is
* one that we can use as soon as its done, or whether it's one that
* we should keep around to see if we can do better. In the latter case,
* a periodic call to entry_guards_upgrade_waiting_circuits() will
* eventually upgrade it.
**/
/* DOCDOC -- expand this.
*
* Information invariants:
*
* [x] whenever a guard becomes unreachable, clear its usable_filtered flag.
*
* [x] Whenever a guard becomes reachable or maybe-reachable, if its filtered
* flag is set, set its usable_filtered flag.
*
* [x] Whenever we get a new consensus, call update_from_consensus(). (LATER.)
*
* [x] Whenever the configuration changes in a relevant way, update the
* filtered/usable flags. (LATER.)
*
* [x] Whenever we add a guard to the sample, make sure its filtered/usable
* flags are set as possible.
*
* [x] Whenever we remove a guard from the sample, remove it from the primary
* and confirmed lists.
*
* [x] When we make a guard confirmed, update the primary list.
*
* [x] When we make a guard filtered or unfiltered, update the primary list.
*
* [x] When we are about to pick a guard, make sure that the primary list is
* full.
*
* [x] Before calling sample_reachable_filtered_entry_guards(), make sure
* that the filtered, primary, and confirmed flags are up-to-date.
*
* [x] Call entry_guard_consider_retry every time we are about to check
* is_usable_filtered or is_reachable, and every time we set
* is_filtered to 1.
*
* [x] Call entry_guards_changed_for_guard_selection() whenever we update
* a persistent field.
*/
#define ENTRYNODES_PRIVATE
#include "or.h"
#include "bridges.h"
#include "circpathbias.h"
#include "circuitbuild.h"
#include "circuitlist.h"
#include "circuitstats.h"
#include "config.h"
#include "confparse.h"
#include "connection.h"
#include "connection_or.h"
#include "control.h"
#include "directory.h"
#include "entrynodes.h"
#include "main.h"
#include "microdesc.h"
#include "networkstatus.h"
#include "nodelist.h"
#include "policies.h"
#include "router.h"
#include "routerlist.h"
#include "routerparse.h"
#include "routerset.h"
#include "transports.h"
#include "statefile.h"
static smartlist_t *guard_contexts = NULL;
static guard_selection_t *curr_guard_context = NULL;
/** A value of 1 means that at least one context has changed,
* and those changes need to be flushed to disk. */
static int entry_guards_dirty = 0;
static const node_t *choose_random_entry_impl(guard_selection_t *gs,
cpath_build_state_t *state,
int for_directory,
dirinfo_type_t dirtype,
int *n_options_out);
static void entry_guard_set_filtered_flags(const or_options_t *options,
guard_selection_t *gs,
entry_guard_t *guard);
static void pathbias_check_use_success_count(entry_guard_t *guard);
static void pathbias_check_close_success_count(entry_guard_t *guard);
static int node_is_possible_guard(const node_t *node);
static int node_passes_guard_filter(const or_options_t *options,
const node_t *node);
static entry_guard_t *entry_guard_add_to_sample_impl(guard_selection_t *gs,
const uint8_t *rsa_id_digest,
const char *nickname,
const tor_addr_port_t *bridge_addrport);
static entry_guard_t *get_sampled_guard_by_bridge_addr(guard_selection_t *gs,
const tor_addr_port_t *addrport);
static int entry_guard_obeys_restriction(const entry_guard_t *guard,
const entry_guard_restriction_t *rst);
/** Return 0 if we should apply guardfraction information found in the
* consensus. A specific consensus can be specified with the
* ns argument, if NULL the most recent one will be picked.*/
int
should_apply_guardfraction(const networkstatus_t *ns)
{
/* We need to check the corresponding torrc option and the consensus
* parameter if we need to. */
const or_options_t *options = get_options();
/* If UseGuardFraction is 'auto' then check the same-named consensus
* parameter. If the consensus parameter is not present, default to
* "off". */
if (options->UseGuardFraction == -1) {
return networkstatus_get_param(ns, "UseGuardFraction",
0, /* default to "off" */
0, 1);
}
return options->UseGuardFraction;
}
/**
* Try to determine the correct type for a selection named "name",
* if type is GS_TYPE_INFER.
*/
STATIC guard_selection_type_t
guard_selection_infer_type(guard_selection_type_t type,
const char *name)
{
if (type == GS_TYPE_INFER) {
if (!strcmp(name, "legacy"))
type = GS_TYPE_LEGACY;
else if (!strcmp(name, "bridges"))
type = GS_TYPE_BRIDGE;
else if (!strcmp(name, "restricted"))
type = GS_TYPE_RESTRICTED;
else
type = GS_TYPE_NORMAL;
}
return type;
}
/**
* Allocate and return a new guard_selection_t, with the name name.
*/
STATIC guard_selection_t *
guard_selection_new(const char *name,
guard_selection_type_t type)
{
guard_selection_t *gs;
type = guard_selection_infer_type(type, name);
gs = tor_malloc_zero(sizeof(*gs));
gs->name = tor_strdup(name);
gs->type = type;
gs->chosen_entry_guards = smartlist_new();
gs->sampled_entry_guards = smartlist_new();
gs->confirmed_entry_guards = smartlist_new();
gs->primary_entry_guards = smartlist_new();
return gs;
}
/**
* Return the guard selection called name. If there is none, and
* create_if_absent is true, then create and return it. If there
* is none, and create_if_absent is false, then return NULL.
*/
STATIC guard_selection_t *
get_guard_selection_by_name(const char *name,
guard_selection_type_t type,
int create_if_absent)
{
if (!guard_contexts) {
guard_contexts = smartlist_new();
}
SMARTLIST_FOREACH_BEGIN(guard_contexts, guard_selection_t *, gs) {
if (!strcmp(gs->name, name))
return gs;
} SMARTLIST_FOREACH_END(gs);
if (! create_if_absent)
return NULL;
log_debug(LD_GUARD, "Creating a guard selection called %s", name);
guard_selection_t *new_selection = guard_selection_new(name, type);
smartlist_add(guard_contexts, new_selection);
return new_selection;
}
/**
* Allocate the first guard context that we're planning to use,
* and make it the current context.
*/
static void
create_initial_guard_context(void)
{
tor_assert(! curr_guard_context);
if (!guard_contexts) {
guard_contexts = smartlist_new();
}
guard_selection_type_t type = GS_TYPE_INFER;
const char *name = choose_guard_selection(
get_options(),
networkstatus_get_live_consensus(approx_time()),
NULL,
&type);
tor_assert(name); // "name" can only be NULL if we had an old name.
tor_assert(type != GS_TYPE_INFER);
log_notice(LD_GUARD, "Starting with guard context \"%s\"", name);
curr_guard_context = get_guard_selection_by_name(name, type, 1);
}
/** Get current default guard_selection_t, creating it if necessary */
guard_selection_t *
get_guard_selection_info(void)
{
if (!curr_guard_context) {
create_initial_guard_context();
}
return curr_guard_context;
}
/** Return the list of entry guards for a guard_selection_t, creating it
* if necessary. */
const smartlist_t *
get_entry_guards_for_guard_selection(guard_selection_t *gs)
{
tor_assert(gs != NULL);
tor_assert(gs->chosen_entry_guards != NULL);
return gs->chosen_entry_guards;
}
/** Return the list of entry guards for the default guard_selection_t,
* creating it if necessary. */
const smartlist_t *
get_entry_guards(void)
{
return get_entry_guards_for_guard_selection(get_guard_selection_info());
}
/** Helper: mark an entry guard as not usable. */
void
entry_guard_mark_bad(entry_guard_t *guard)
{
guard->bad_since = approx_time();
entry_guards_changed();
}
/** Return a statically allocated human-readable description of guard
*/
const char *
entry_guard_describe(const entry_guard_t *guard)
{
static char buf[256];
tor_snprintf(buf, sizeof(buf),
"%s ($%s)",
guard->nickname, hex_str(guard->identity, DIGEST_LEN));
return buf;
}
/** Return guard's 20-byte RSA identity digest */
const char *
entry_guard_get_rsa_id_digest(const entry_guard_t *guard)
{
return guard->identity;
}
/** Return the pathbias state associated with guard. */
guard_pathbias_t *
entry_guard_get_pathbias_state(entry_guard_t *guard)
{
return &guard->pb;
}
HANDLE_IMPL(entry_guard, entry_guard_t, ATTR_UNUSED STATIC)
/** Return an interval betweeen 'now' and 'max_backdate' seconds in the past,
* chosen uniformly at random. We use this before recording persistent
* dates, so that we aren't leaking exactly when we recorded it.
*/
MOCK_IMPL(STATIC time_t,
randomize_time,(time_t now, time_t max_backdate))
{
tor_assert(max_backdate > 0);
time_t earliest = now - max_backdate;
time_t latest = now;
if (earliest <= 0)
earliest = 1;
if (latest <= earliest)
latest = earliest + 1;
return crypto_rand_time_range(earliest, latest);
}
/**
* @name parameters for networkstatus algorithm
*
* These parameters are taken from the consensus; some are overrideable in
* the torrc.
*/
/**@{*/
/**
* We never let our sampled guard set grow larger than this fraction
* of the guards on the network.
*/
STATIC double
get_max_sample_threshold(void)
{
int32_t pct =
networkstatus_get_param(NULL, "guard-max-sample-threshold-percent",
DFLT_MAX_SAMPLE_THRESHOLD_PERCENT,
1, 100);
return pct / 100.0;
}
/**
* We always try to make our sample contain at least this many guards.
*
* XXXX prop271 spec deviation There was a MIN_SAMPLE_THRESHOLD in the
* proposal, but I removed it in favor of MIN_FILTERED_SAMPLE_SIZE. -NM
*/
STATIC int
get_min_filtered_sample_size(void)
{
return networkstatus_get_param(NULL, "guard-min-filtered-sample-size",
DFLT_MIN_FILTERED_SAMPLE_SIZE,
1, INT32_MAX);
}
/**
* If a guard is unlisted for this many days in a row, we remove it.
*/
STATIC int
get_remove_unlisted_guards_after_days(void)
{
return networkstatus_get_param(NULL,
"guard-remove-unlisted-guards-after-days",
DFLT_REMOVE_UNLISTED_GUARDS_AFTER_DAYS,
1, 365*10);
}
/**
* We remove unconfirmed guards from the sample after this many days,
* regardless of whether they are listed or unlisted.
*/
STATIC int
get_guard_lifetime_days(void)
{
return networkstatus_get_param(NULL,
"guard-lifetime-days",
DFLT_GUARD_LIFETIME_DAYS, 1, 365*10);
}
/**
* We remove confirmed guards from the sample if they were sampled
* GUARD_LIFETIME_DAYS ago and confirmed this many days ago.
*/
STATIC int
get_guard_confirmed_min_lifetime_days(void)
{
return networkstatus_get_param(NULL, "guard-confirmed-min-lifetime-days",
DFLT_GUARD_CONFIRMED_MIN_LIFETIME_DAYS,
1, 365*10);
}
/**
* How many guards do we try to keep on our primary guard list?
*/
STATIC int
get_n_primary_guards(void)
{
return networkstatus_get_param(NULL, "guard-n-primary-guards",
DFLT_N_PRIMARY_GUARDS, 1, INT32_MAX);
}
/**
* If we haven't successfully built or used a circuit in this long, then
* consider that the internet is probably down.
*/
STATIC int
get_internet_likely_down_interval(void)
{
return networkstatus_get_param(NULL, "guard-internet-likely-down-interval",
DFLT_INTERNET_LIKELY_DOWN_INTERVAL,
1, INT32_MAX);
}
/**
* If we're trying to connect to a nonprimary guard for at least this
* many seconds, and we haven't gotten the connection to work, we will treat
* lower-priority guards as usable.
*/
STATIC int
get_nonprimary_guard_connect_timeout(void)
{
return networkstatus_get_param(NULL,
"guard-nonprimary-guard-connect-timeout",
DFLT_NONPRIMARY_GUARD_CONNECT_TIMEOUT,
1, INT32_MAX);
}
/**
* If a circuit has been sitting around in 'waiting for better guard' state
* for at least this long, we'll expire it.
*/
STATIC int
get_nonprimary_guard_idle_timeout(void)
{
return networkstatus_get_param(NULL,
"guard-nonprimary-guard-idle-timeout",
DFLT_NONPRIMARY_GUARD_IDLE_TIMEOUT,
1, INT32_MAX);
}
/**
* If our configuration retains fewer than this fraction of guards from the
* torrc, we are in a restricted setting.
*/
STATIC double
get_meaningful_restriction_threshold(void)
{
int32_t pct = networkstatus_get_param(NULL,
"guard-meaningful-restriction-percent",
DFLT_MEANINGFUL_RESTRICTION_PERCENT,
1, INT32_MAX);
return pct / 100.0;
}
/**
* If our configuration retains fewer than this fraction of guards from the
* torrc, we are in an extremely restricted setting, and should warn.
*/
STATIC double
get_extreme_restriction_threshold(void)
{
int32_t pct = networkstatus_get_param(NULL,
"guard-extreme-restriction-percent",
DFLT_EXTREME_RESTRICTION_PERCENT,
1, INT32_MAX);
return pct / 100.0;
}
/**@}*/
/**
* Given our options and our list of nodes, return the name of the
* guard selection that we should use. Return NULL for "use the
* same selection you were using before.
*/
STATIC const char *
choose_guard_selection(const or_options_t *options,
const networkstatus_t *live_ns,
const char *old_selection,
guard_selection_type_t *type_out)
{
tor_assert(options);
tor_assert(type_out);
if (options->UseDeprecatedGuardAlgorithm) {
*type_out = GS_TYPE_LEGACY;
return "legacy";
}
if (options->UseBridges) {
*type_out = GS_TYPE_BRIDGE;
return "bridges";
}
if (! live_ns) {
/* without a networkstatus, we can't tell any more than that. */
*type_out = GS_TYPE_NORMAL;
return "default";
}
const smartlist_t *nodes = nodelist_get_list();
int n_guards = 0, n_passing_filter = 0;
SMARTLIST_FOREACH_BEGIN(nodes, const node_t *, node) {
if (node_is_possible_guard(node)) {
++n_guards;
if (node_passes_guard_filter(options, node)) {
++n_passing_filter;
}
}
} SMARTLIST_FOREACH_END(node);
/* XXXX prop271 spec deviation -- separate 'high' and 'low' thresholds
* to prevent flapping */
const int meaningful_threshold_high =
(int)(n_guards * get_meaningful_restriction_threshold() * 1.05);
const int meaningful_threshold_mid =
(int)(n_guards * get_meaningful_restriction_threshold());
const int meaningful_threshold_low =
(int)(n_guards * get_meaningful_restriction_threshold() * .95);
const int extreme_threshold =
(int)(n_guards * get_extreme_restriction_threshold());
/*
If we have no previous selection, then we're "restricted" iff we are
below the meaningful restriction threshold. That's easy enough.
But if we _do_ have a previous selection, we make it a little
"sticky": we only move from "restricted" to "default" when we find
that we're above the threshold plus 5%, and we only move from
"default" to "restricted" when we're below the threshold minus 5%.
That should prevent us from flapping back and forth if we happen to
be hovering very close to the default.
The extreme threshold is for warning only.
*/
static int have_warned_extreme_threshold = 0;
if (n_passing_filter < extreme_threshold &&
! have_warned_extreme_threshold) {
have_warned_extreme_threshold = 1;
const double exclude_frac =
(n_guards - n_passing_filter) / (double)n_guards;
log_warn(LD_GUARD, "Your configuration excludes %d%% of all possible "
"guards. That's likely to make you stand out from the "
"rest of the world.", (int)(exclude_frac * 100));
}
/* Easy case: no previous selection */
if (old_selection == NULL) {
if (n_passing_filter >= meaningful_threshold_mid) {
*type_out = GS_TYPE_NORMAL;
return "default";
} else {
*type_out = GS_TYPE_RESTRICTED;
return "restricted";
}
}
/* Trickier case: we do have a previous selection */
if (n_passing_filter >= meaningful_threshold_high) {
*type_out = GS_TYPE_NORMAL;
return "default";
} else if (n_passing_filter < meaningful_threshold_low) {
*type_out = GS_TYPE_RESTRICTED;
return "restricted";
} else {
return NULL;
}
}
/**
* Check whether we should switch from our current guard selection to a
* different one. If so, switch and return 1. Return 0 otherwise.
*
* On a 1 return, the caller should mark all currently live circuits
* unusable for new streams.
*/
int
update_guard_selection_choice(const or_options_t *options)
{
if (!curr_guard_context) {
create_initial_guard_context();
return 1;
}
const char *cur_name = curr_guard_context->name;
guard_selection_type_t type = GS_TYPE_INFER;
const char *new_name = choose_guard_selection(
options,
networkstatus_get_live_consensus(approx_time()),
cur_name,
&type);
tor_assert(new_name);
tor_assert(type != GS_TYPE_INFER);
if (! strcmp(cur_name, new_name)) {
log_debug(LD_GUARD,
"Staying with guard context \"%s\" (no change)", new_name);
return 0; // No change
}
log_notice(LD_GUARD, "Switching to guard context \"%s\" (was using \"%s\")",
new_name, cur_name);
guard_selection_t *new_guard_context;
new_guard_context = get_guard_selection_by_name(new_name, type, 1);
tor_assert(new_guard_context);
tor_assert(new_guard_context != curr_guard_context);
curr_guard_context = new_guard_context;
/*
Be sure to call:
circuit_mark_all_unused_circs();
circuit_mark_all_dirty_circs_as_unusable();
*/
return 1;
}
/**
* Return true iff node has all the flags needed for us to consider it
* a possible guard when sampling guards.
*/
static int
node_is_possible_guard(const node_t *node)
{
/* The "GUARDS" set is all nodes in the nodelist for which this predicate
* holds. */
/* XXXX -- prop271 spec deviation. We require node_is_dir() here. */
tor_assert(node);
return (node->is_possible_guard &&
node->is_stable &&
node->is_fast &&
node->is_valid &&
node_is_dir(node));
}
/**
* Return the sampled guard with the RSA identity digest rsa_id, or
* NULL if we don't have one. */
STATIC entry_guard_t *
get_sampled_guard_with_id(guard_selection_t *gs,
const uint8_t *rsa_id)
{
tor_assert(gs);
tor_assert(rsa_id);
SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
if (tor_memeq(guard->identity, rsa_id, DIGEST_LEN))
return guard;
} SMARTLIST_FOREACH_END(guard);
return NULL;
}
/** If gs contains a sampled entry guard matching bridge,
* return that guard. Otherwise return NULL. */
static entry_guard_t *
get_sampled_guard_for_bridge(guard_selection_t *gs,
const bridge_info_t *bridge)
{
const uint8_t *id = bridge_get_rsa_id_digest(bridge);
const tor_addr_port_t *addrport = bridge_get_addr_port(bridge);
entry_guard_t *guard;
if (id) {
guard = get_sampled_guard_with_id(gs, id);
if (guard)
return guard;
}
if (BUG(!addrport))
return NULL; // LCOV_EXCL_LINE
guard = get_sampled_guard_by_bridge_addr(gs, addrport);
if (! guard || (id && tor_memneq(id, guard->identity, DIGEST_LEN)))
return NULL;
else
return guard;
}
/** If we know a bridge_info_t matching guard, return that
* bridge. Otherwise return NULL. */
static bridge_info_t *
get_bridge_info_for_guard(const entry_guard_t *guard)
{
if (! tor_digest_is_zero(guard->identity)) {
bridge_info_t *bridge = find_bridge_by_digest(guard->identity);
if (bridge)
return bridge;
}
if (BUG(guard->bridge_addr == NULL))
return NULL;
return get_configured_bridge_by_addr_port_digest(&guard->bridge_addr->addr,
guard->bridge_addr->port,
NULL);
}
/**
* Return true iff we have a sampled guard with the RSA identity digest
* rsa_id. */
static inline int
have_sampled_guard_with_id(guard_selection_t *gs, const uint8_t *rsa_id)
{
return get_sampled_guard_with_id(gs, rsa_id) != NULL;
}
/**
* Allocate a new entry_guard_t object for node, add it to the
* sampled entry guards in gs, and return it. node must
* not currently be a sampled guard in gs.
*/
STATIC entry_guard_t *
entry_guard_add_to_sample(guard_selection_t *gs,
const node_t *node)
{
log_info(LD_GUARD, "Adding %s as to the entry guard sample set.",
node_describe(node));
return entry_guard_add_to_sample_impl(gs,
(const uint8_t*)node->identity,
node_get_nickname(node),
NULL);
}
/**
* Backend: adds a new sampled guard to gs, with given identity,
* nickname, and ORPort. rsa_id_digest and bridge_addrport are
* optional, but we need one of them. nickname is optional.
*/
static entry_guard_t *
entry_guard_add_to_sample_impl(guard_selection_t *gs,
const uint8_t *rsa_id_digest,
const char *nickname,
const tor_addr_port_t *bridge_addrport)
{
const int GUARD_LIFETIME = get_guard_lifetime_days() * 86400;
tor_assert(gs);
// XXXX prop271 take ed25519 identity here too.
/* make sure that the guard is not already sampled. */
if (rsa_id_digest && BUG(have_sampled_guard_with_id(gs, rsa_id_digest)))
return NULL; // LCOV_EXCL_LINE
/* Make sure we can actually identify the guard. */
if (BUG(!rsa_id_digest && !bridge_addrport))
return NULL; // LCOV_EXCL_LINE
entry_guard_t *guard = tor_malloc_zero(sizeof(entry_guard_t));
/* persistent fields */
guard->is_persistent = (rsa_id_digest != NULL);
guard->selection_name = tor_strdup(gs->name);
if (rsa_id_digest)
memcpy(guard->identity, rsa_id_digest, DIGEST_LEN);
if (nickname)
strlcpy(guard->nickname, nickname, sizeof(guard->nickname));
guard->sampled_on_date = randomize_time(approx_time(), GUARD_LIFETIME/10);
tor_free(guard->sampled_by_version);
guard->sampled_by_version = tor_strdup(VERSION);
guard->currently_listed = 1;
guard->confirmed_idx = -1;
/* non-persistent fields */
guard->is_reachable = GUARD_REACHABLE_MAYBE;
if (bridge_addrport)
guard->bridge_addr = tor_memdup(bridge_addrport, sizeof(*bridge_addrport));
smartlist_add(gs->sampled_entry_guards, guard);
guard->in_selection = gs;
entry_guard_set_filtered_flags(get_options(), gs, guard);
entry_guards_changed_for_guard_selection(gs);
return guard;
}
/**
* Add an entry guard to the "bridges" guard selection sample, with
* information taken from bridge. Return that entry guard.
*/
static entry_guard_t *
entry_guard_add_bridge_to_sample(guard_selection_t *gs,
const bridge_info_t *bridge)
{
const uint8_t *id_digest = bridge_get_rsa_id_digest(bridge);
const tor_addr_port_t *addrport = bridge_get_addr_port(bridge);
tor_assert(addrport);
return entry_guard_add_to_sample_impl(gs, id_digest, NULL, addrport);
}
/**
* Return the entry_guard_t in gs whose address is addrport,
* or NULL if none exists.
*/
static entry_guard_t *
get_sampled_guard_by_bridge_addr(guard_selection_t *gs,
const tor_addr_port_t *addrport)
{
if (! gs)
return NULL;
if (BUG(!addrport))
return NULL;
SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, g) {
if (g->bridge_addr && tor_addr_port_eq(addrport, g->bridge_addr))
return g;
} SMARTLIST_FOREACH_END(g);
return NULL;
}
/** Update the guard subsystem's knowledge of the identity of the bridge
* at addrport. Idempotent.
*/
void
entry_guard_learned_bridge_identity(const tor_addr_port_t *addrport,
const uint8_t *rsa_id_digest)
{
guard_selection_t *gs = get_guard_selection_by_name("bridges",
GS_TYPE_BRIDGE,
0);
if (!gs)
return;
entry_guard_t *g = get_sampled_guard_by_bridge_addr(gs, addrport);
if (!g)
return;
int make_persistent = 0;
if (tor_digest_is_zero(g->identity)) {
memcpy(g->identity, rsa_id_digest, DIGEST_LEN);
make_persistent = 1;
} else if (tor_memeq(g->identity, rsa_id_digest, DIGEST_LEN)) {
/* Nothing to see here; we learned something we already knew. */
if (BUG(! g->is_persistent))
make_persistent = 1;
} else {
char old_id[HEX_DIGEST_LEN+1];
base16_encode(old_id, sizeof(old_id), g->identity, sizeof(g->identity));
log_warn(LD_BUG, "We 'learned' an identity %s for a bridge at %s:%d, but "
"we already knew a different one (%s). Ignoring the new info as "
"possibly bogus.",
hex_str((const char *)rsa_id_digest, DIGEST_LEN),
fmt_and_decorate_addr(&addrport->addr), addrport->port,
old_id);
return; // redundant, but let's be clear: we're not making this persistent.
}
if (make_persistent) {
g->is_persistent = 1;
entry_guards_changed_for_guard_selection(gs);
}
}
/**
* Return the number of sampled guards in gs that are "filtered"
* (that is, we're willing to connect to them) and that are "usable"
* (that is, either "reachable" or "maybe reachable").
*
* If a restriction is provided in rst, do not count any guards that
* violate it.
*/
STATIC int
num_reachable_filtered_guards(guard_selection_t *gs,
const entry_guard_restriction_t *rst)
{
int n_reachable_filtered_guards = 0;
SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
entry_guard_consider_retry(guard);
if (! entry_guard_obeys_restriction(guard, rst))
continue;
if (guard->is_usable_filtered_guard)
++n_reachable_filtered_guards;
} SMARTLIST_FOREACH_END(guard);
return n_reachable_filtered_guards;
}
/** Return the actual maximum size for the sample in gs,
* given that we know about n_guards total. */
static int
get_max_sample_size(guard_selection_t *gs,
int n_guards)
{
const int using_bridges = (gs->type == GS_TYPE_BRIDGE);
const int min_sample = get_min_filtered_sample_size();
/* XXXX prop271 spec deviation with bridges, max_sample is "all of them" */
if (using_bridges)
return n_guards;
const int max_sample = (int)(n_guards * get_max_sample_threshold());
if (max_sample < min_sample) // XXXX prop271 spec deviation
return min_sample;
else
return max_sample;
}
/**
* Return a smartlist of the all the guards that are not currently
* members of the sample (GUARDS - SAMPLED_GUARDS). The elements of
* this list are node_t pointers in the non-bridge case, and
* bridge_info_t pointers in the bridge case. Set *n_guards_out/b>
* to the number of guards that we found in GUARDS, including those
* that were already sampled.
*/
static smartlist_t *
get_eligible_guards(guard_selection_t *gs,
int *n_guards_out)
{
/* Construct eligible_guards as GUARDS - SAMPLED_GUARDS */
smartlist_t *eligible_guards = smartlist_new();
int n_guards = 0; // total size of "GUARDS"
if (gs->type == GS_TYPE_BRIDGE) {
const smartlist_t *bridges = bridge_list_get();
SMARTLIST_FOREACH_BEGIN(bridges, bridge_info_t *, bridge) {
++n_guards;
if (NULL != get_sampled_guard_for_bridge(gs, bridge)) {
continue;
}
smartlist_add(eligible_guards, bridge);
} SMARTLIST_FOREACH_END(bridge);
} else {
const smartlist_t *nodes = nodelist_get_list();
const int n_sampled = smartlist_len(gs->sampled_entry_guards);
/* Build a bloom filter of our current guards: let's keep this O(N). */
digestset_t *sampled_guard_ids = digestset_new(n_sampled);
SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, const entry_guard_t *,
guard) {
digestset_add(sampled_guard_ids, guard->identity);
} SMARTLIST_FOREACH_END(guard);
SMARTLIST_FOREACH_BEGIN(nodes, const node_t *, node) {
if (! node_is_possible_guard(node))
continue;
++n_guards;
if (digestset_contains(sampled_guard_ids, node->identity))
continue;
smartlist_add(eligible_guards, (node_t*)node);
} SMARTLIST_FOREACH_END(node);
/* Now we can free that bloom filter. */
digestset_free(sampled_guard_ids);
}
*n_guards_out = n_guards;
return eligible_guards;
}
/** Helper: given a smartlist of either bridge_info_t (if gs->type is
* GS_TYPE_BRIDGE) or node_t (otherwise), pick one that can be a guard,
* add it as a guard, remove it from the list, and return a new
* entry_guard_t. Return NULL on failure. */
static entry_guard_t *
select_and_add_guard_item_for_sample(guard_selection_t *gs,
smartlist_t *eligible_guards)
{
entry_guard_t *added_guard;
if (gs->type == GS_TYPE_BRIDGE) {
const bridge_info_t *bridge = smartlist_choose(eligible_guards);
if (BUG(!bridge))
return NULL; // LCOV_EXCL_LINE
smartlist_remove(eligible_guards, bridge);
added_guard = entry_guard_add_bridge_to_sample(gs, bridge);
} else {
const node_t *node =
node_sl_choose_by_bandwidth(eligible_guards, WEIGHT_FOR_GUARD);
if (BUG(!node))
return NULL; // LCOV_EXCL_LINE
smartlist_remove(eligible_guards, node);
added_guard = entry_guard_add_to_sample(gs, node);
}
return added_guard;
}
/**
* Add new guards to the sampled guards in gs until there are
* enough usable filtered guards, but never grow the sample beyond its
* maximum size. Return the last guard added, or NULL if none were
* added.
*/
STATIC entry_guard_t *
entry_guards_expand_sample(guard_selection_t *gs)
{
tor_assert(gs);
int n_sampled = smartlist_len(gs->sampled_entry_guards);
entry_guard_t *added_guard = NULL;
int n_usable_filtered_guards = num_reachable_filtered_guards(gs, NULL);
int n_guards = 0;
smartlist_t *eligible_guards = get_eligible_guards(gs, &n_guards);
const int max_sample = get_max_sample_size(gs, n_guards);
const int min_filtered_sample = get_min_filtered_sample_size();
log_info(LD_GUARD, "Expanding the sample guard set. We have %d guards "
"in the sample, and %d eligible guards to extend it with.",
n_sampled, smartlist_len(eligible_guards));
while (n_usable_filtered_guards < min_filtered_sample) {
/* Has our sample grown too large to expand? */
if (n_sampled >= max_sample) {
log_info(LD_GUARD, "Not expanding the guard sample any further; "
"just hit the maximum sample threshold of %d",
max_sample);
goto done;
}
/* Did we run out of guards? */
if (smartlist_len(eligible_guards) == 0) {
/* LCOV_EXCL_START
As long as MAX_SAMPLE_THRESHOLD makes can't be adjusted to
allow all guards to be sampled, this can't be reached.
*/
log_info(LD_GUARD, "Not expanding the guard sample any further; "
"just ran out of eligible guards");
goto done;
/* LCOV_EXCL_STOP */
}
/* Otherwise we can add at least one new guard. */
added_guard = select_and_add_guard_item_for_sample(gs, eligible_guards);
if (!added_guard)
goto done; // LCOV_EXCL_LINE -- only fails on BUG.
++n_sampled;
if (added_guard->is_usable_filtered_guard)
++n_usable_filtered_guards;
}
done:
smartlist_free(eligible_guards);
return added_guard;
}
/**
* Helper: guard has just been removed from the sampled guards:
* also remove it from primary and confirmed. */
static void
remove_guard_from_confirmed_and_primary_lists(guard_selection_t *gs,
entry_guard_t *guard)
{
if (guard->is_primary) {
guard->is_primary = 0;
smartlist_remove_keeporder(gs->primary_entry_guards, guard);
} else {
if (BUG(smartlist_contains(gs->primary_entry_guards, guard))) {
smartlist_remove_keeporder(gs->primary_entry_guards, guard);
}
}
if (guard->confirmed_idx >= 0) {
entry_guard_t *found_guard = NULL;
if (guard->confirmed_idx < smartlist_len(gs->confirmed_entry_guards))
found_guard = smartlist_get(gs->confirmed_entry_guards,
guard->confirmed_idx);
if (BUG(guard != found_guard)) {
// LCOV_EXCL_START
smartlist_remove_keeporder(gs->confirmed_entry_guards, guard);
// LCOV_EXCL_STOP
} else {
smartlist_del_keeporder(gs->confirmed_entry_guards,
guard->confirmed_idx);
}
guard->confirmed_idx = -1;
guard->confirmed_on_date = 0;
} else {
if (BUG(smartlist_contains(gs->confirmed_entry_guards, guard))) {
// LCOV_EXCL_START
smartlist_remove_keeporder(gs->confirmed_entry_guards, guard);
// LCOV_EXCL_STOP
}
}
}
/** Return true iff guard is currently "listed" -- that is, it
* appears in the consensus, or as a configured bridge (as
* appropriate) */
MOCK_IMPL(STATIC int,
entry_guard_is_listed,(guard_selection_t *gs, const entry_guard_t *guard))
{
if (gs->type == GS_TYPE_BRIDGE) {
return NULL != get_bridge_info_for_guard(guard);
} else {
const node_t *node = node_get_by_id(guard->identity);
return node && node_is_possible_guard(node);
}
}
/**
* Update the status of all sampled guards based on the arrival of a
* new consensus networkstatus document. This will include marking
* some guards as listed or unlisted, and removing expired guards. */
STATIC void
sampled_guards_update_from_consensus(guard_selection_t *gs)
{
/*XXXX prop271 consider splitting this function up. */
tor_assert(gs);
const int REMOVE_UNLISTED_GUARDS_AFTER =
(get_remove_unlisted_guards_after_days() * 86400);
const int unlisted_since_slop = REMOVE_UNLISTED_GUARDS_AFTER / 5;
// It's important to use only a live consensus here; we don't want to
// make changes based on anything expired or old.
if (gs->type != GS_TYPE_BRIDGE) {
networkstatus_t *ns = networkstatus_get_live_consensus(approx_time());
log_info(LD_GUARD, "Updating sampled guard status based on received "
"consensus.");
if (! ns || ns->valid_until < approx_time()) {
log_info(LD_GUARD, "Hey, there wasn't a valid consensus. Ignoring");
return;
}
}
int n_changes = 0;
/* First: Update listed/unlisted. */
SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
/* XXXX prop271 check ed ID too */
const int is_listed = entry_guard_is_listed(gs, guard);
if (is_listed && ! guard->currently_listed) {
++n_changes;
guard->currently_listed = 1;
guard->unlisted_since_date = 0;
log_info(LD_GUARD, "Sampled guard %s is now listed again.",
entry_guard_describe(guard));
} else if (!is_listed && guard->currently_listed) {
++n_changes;
guard->currently_listed = 0;
guard->unlisted_since_date = randomize_time(approx_time(),
unlisted_since_slop);
log_info(LD_GUARD, "Sampled guard %s is now unlisted.",
entry_guard_describe(guard));
} else if (is_listed && guard->currently_listed) {
log_debug(LD_GUARD, "Sampled guard %s is still listed.",
entry_guard_describe(guard));
} else {
tor_assert(! is_listed && ! guard->currently_listed);
log_debug(LD_GUARD, "Sampled guard %s is still unlisted.",
entry_guard_describe(guard));
}
/* Clean up unlisted_since_date, just in case. */
if (guard->currently_listed && guard->unlisted_since_date) {
++n_changes;
guard->unlisted_since_date = 0;
log_warn(LD_BUG, "Sampled guard %s was listed, but with "
"unlisted_since_date set. Fixing.",
entry_guard_describe(guard));
} else if (!guard->currently_listed && ! guard->unlisted_since_date) {
++n_changes;
guard->unlisted_since_date = randomize_time(approx_time(),
unlisted_since_slop);
log_warn(LD_BUG, "Sampled guard %s was unlisted, but with "
"unlisted_since_date unset. Fixing.",
entry_guard_describe(guard));
}
} SMARTLIST_FOREACH_END(guard);
const time_t remove_if_unlisted_since =
approx_time() - REMOVE_UNLISTED_GUARDS_AFTER;
const time_t maybe_remove_if_sampled_before =
approx_time() - (get_guard_lifetime_days() * 86400);
const time_t remove_if_confirmed_before =
approx_time() - (get_guard_confirmed_min_lifetime_days() * 86400);
/* Then: remove the ones that have been junk for too long */
SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
int remove = 0;
if (guard->currently_listed == 0 &&
guard->unlisted_since_date < remove_if_unlisted_since) {
/*
"We have a live consensus, and {IS_LISTED} is false, and
{FIRST_UNLISTED_AT} is over {REMOVE_UNLISTED_GUARDS_AFTER}
days in the past."
*/
log_info(LD_GUARD, "Removing sampled guard %s: it has been unlisted "
"for over %d days", entry_guard_describe(guard),
get_remove_unlisted_guards_after_days());
remove = 1;
} else if (guard->sampled_on_date < maybe_remove_if_sampled_before) {
/* We have a live consensus, and {ADDED_ON_DATE} is over
{GUARD_LIFETIME} ago, *and* {CONFIRMED_ON_DATE} is either
"never", or over {GUARD_CONFIRMED_MIN_LIFETIME} ago.
*/
if (guard->confirmed_on_date == 0) {
remove = 1;
log_info(LD_GUARD, "Removing sampled guard %s: it was sampled "
"over %d days ago, but never confirmed.",
entry_guard_describe(guard),
get_guard_lifetime_days());
} else if (guard->confirmed_on_date < remove_if_confirmed_before) {
remove = 1;
log_info(LD_GUARD, "Removing sampled guard %s: it was sampled "
"over %d days ago, and confirmed over %d days ago.",
entry_guard_describe(guard),
get_guard_lifetime_days(),
get_guard_confirmed_min_lifetime_days());
}
}
if (remove) {
++n_changes;
SMARTLIST_DEL_CURRENT(gs->sampled_entry_guards, guard);
remove_guard_from_confirmed_and_primary_lists(gs, guard);
entry_guard_free(guard);
}
} SMARTLIST_FOREACH_END(guard);
if (n_changes) {
gs->primary_guards_up_to_date = 0;
entry_guards_update_filtered_sets(gs);
/* We don't need to rebuild the confirmed list right here -- we may have
* removed confirmed guards above, but we can't have added any new
* confirmed guards.
*/
entry_guards_changed_for_guard_selection(gs);
}
}
/**
* Return true iff node is a Tor relay that we are configured to
* be able to connect to. */
static int
node_passes_guard_filter(const or_options_t *options,
const node_t *node)
{
/* NOTE: Make sure that this function stays in sync with
* options_transition_affects_entry_guards */
if (routerset_contains_node(options->ExcludeNodes, node))
return 0;
/* XXXX -- prop271 spec deviation -- add entrynodes to spec. */
if (options->EntryNodes &&
!routerset_contains_node(options->EntryNodes, node))
return 0;
if (!fascist_firewall_allows_node(node, FIREWALL_OR_CONNECTION, 0))
return 0;
if (node_is_a_configured_bridge(node))
return 0;
return 1;
}
/** Helper: Return true iff bridge passes our configuration
* filter-- if it is a relay that we are configured to be able to
* connect to. */
static int
bridge_passes_guard_filter(const or_options_t *options,
const bridge_info_t *bridge)
{
tor_assert(bridge);
if (!bridge)
return 0;
if (routerset_contains_bridge(options->ExcludeNodes, bridge))
return 0;
/* Ignore entrynodes */
const tor_addr_port_t *addrport = bridge_get_addr_port(bridge);
if (!fascist_firewall_allows_address_addr(&addrport->addr,
addrport->port,
FIREWALL_OR_CONNECTION,
0, 0))
return 0;
return 1;
}
/**
* Return true iff guard is a Tor relay that we are configured to
* be able to connect to, and we haven't disabled it for omission from
* the consensus or path bias issues. */
static int
entry_guard_passes_filter(const or_options_t *options, guard_selection_t *gs,
entry_guard_t *guard)
{
if (guard->currently_listed == 0)
return 0;
if (guard->pb.path_bias_disabled)
return 0;
if (gs->type == GS_TYPE_BRIDGE) {
const bridge_info_t *bridge = get_bridge_info_for_guard(guard);
if (bridge == NULL)
return 0;
return bridge_passes_guard_filter(options, bridge);
} else {
const node_t *node = node_get_by_id(guard->identity);
if (node == NULL) {
// This can happen when currently_listed is true, and we're not updating
// it because we don't have a live consensus.
return 0;
}
return node_passes_guard_filter(options, node);
}
}
/**
* Return true iff guard obeys the restrictions defined in rst.
* (If rst is NULL, there are no restrictions.)
*/
static int
entry_guard_obeys_restriction(const entry_guard_t *guard,
const entry_guard_restriction_t *rst)
{
tor_assert(guard);
if (! rst)
return 1; // No restriction? No problem.
// Only one kind of restriction exists right now
return tor_memneq(guard->identity, rst->exclude_id, DIGEST_LEN);
}
/**
* Update the is_filtered_guard and is_usable_filtered_guard
* flags on guard. */
void
entry_guard_set_filtered_flags(const or_options_t *options,
guard_selection_t *gs,
entry_guard_t *guard)
{
unsigned was_filtered = guard->is_filtered_guard;
guard->is_filtered_guard = 0;
guard->is_usable_filtered_guard = 0;
if (entry_guard_passes_filter(options, gs, guard)) {
guard->is_filtered_guard = 1;
if (guard->is_reachable != GUARD_REACHABLE_NO)
guard->is_usable_filtered_guard = 1;
entry_guard_consider_retry(guard);
}
log_debug(LD_GUARD, "Updated sampled guard %s: filtered=%d; "
"reachable_filtered=%d.", entry_guard_describe(guard),
guard->is_filtered_guard, guard->is_usable_filtered_guard);
if (!bool_eq(was_filtered, guard->is_filtered_guard)) {
/* This guard might now be primary or nonprimary. */
gs->primary_guards_up_to_date = 0;
}
}
/**
* Update the is_filtered_guard and is_usable_filtered_guard
* flag on every guard in gs. */
STATIC void
entry_guards_update_filtered_sets(guard_selection_t *gs)
{
const or_options_t *options = get_options();
SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
entry_guard_set_filtered_flags(options, gs, guard);
} SMARTLIST_FOREACH_END(guard);
}
/**
* Return a random guard from the reachable filtered sample guards
* in gs, subject to the exclusion rules listed in flags.
* Return NULL if no such guard can be found.
*
* Make sure that the sample is big enough, and that all the filter flags
* are set correctly, before calling this function.
*
* If a restriction is provided in rst, do not return any guards that
* violate it.
**/
STATIC entry_guard_t *
sample_reachable_filtered_entry_guards(guard_selection_t *gs,
const entry_guard_restriction_t *rst,
unsigned flags)
{
tor_assert(gs);
entry_guard_t *result = NULL;
const unsigned exclude_confirmed = flags & SAMPLE_EXCLUDE_CONFIRMED;
const unsigned exclude_primary = flags & SAMPLE_EXCLUDE_PRIMARY;
const unsigned exclude_pending = flags & SAMPLE_EXCLUDE_PENDING;
const unsigned no_update_primary = flags & SAMPLE_NO_UPDATE_PRIMARY;
SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
entry_guard_consider_retry(guard);
} SMARTLIST_FOREACH_END(guard);
const int n_reachable_filtered = num_reachable_filtered_guards(gs, rst);
log_info(LD_GUARD, "Trying to sample a reachable guard: We know of %d "
"in the USABLE_FILTERED set.", n_reachable_filtered);
const int min_filtered_sample = get_min_filtered_sample_size();
if (n_reachable_filtered < min_filtered_sample) {
log_info(LD_GUARD, " (That isn't enough. Trying to expand the sample.)");
entry_guards_expand_sample(gs);
}
if (exclude_primary && !gs->primary_guards_up_to_date && !no_update_primary)
entry_guards_update_primary(gs);
/* Build the set of reachable filtered guards. */
smartlist_t *reachable_filtered_sample = smartlist_new();
SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
entry_guard_consider_retry(guard);// redundant, but cheap.
if (! entry_guard_obeys_restriction(guard, rst))
continue;
if (! guard->is_usable_filtered_guard)
continue;
if (exclude_confirmed && guard->confirmed_idx >= 0)
continue;
if (exclude_primary && guard->is_primary)
continue;
if (exclude_pending && guard->is_pending)
continue;
smartlist_add(reachable_filtered_sample, guard);
} SMARTLIST_FOREACH_END(guard);
log_info(LD_GUARD, " (After filters [%x], we have %d guards to consider.)",
flags, smartlist_len(reachable_filtered_sample));
if (smartlist_len(reachable_filtered_sample)) {
result = smartlist_choose(reachable_filtered_sample);
log_info(LD_GUARD, " (Selected %s.)",
result ? entry_guard_describe(result) : "");
}
smartlist_free(reachable_filtered_sample);
return result;
}
/**
* Helper: compare two entry_guard_t by their confirmed_idx values.
* Used to sort the confirmed list.
*/
static int
compare_guards_by_confirmed_idx(const void **a_, const void **b_)
{
const entry_guard_t *a = *a_, *b = *b_;
if (a->confirmed_idx < b->confirmed_idx)
return -1;
else if (a->confirmed_idx > b->confirmed_idx)
return 1;
else
return 0;
}
/**
* Find the confirmed guards from among the sampled guards in gs,
* and put them in confirmed_entry_guards in the correct
* order. Recalculate their indices.
*/
STATIC void
entry_guards_update_confirmed(guard_selection_t *gs)
{
smartlist_clear(gs->confirmed_entry_guards);
SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
if (guard->confirmed_idx >= 0)
smartlist_add(gs->confirmed_entry_guards, guard);
} SMARTLIST_FOREACH_END(guard);
smartlist_sort(gs->confirmed_entry_guards, compare_guards_by_confirmed_idx);
int any_changed = 0;
SMARTLIST_FOREACH_BEGIN(gs->confirmed_entry_guards, entry_guard_t *, guard) {
if (guard->confirmed_idx != guard_sl_idx) {
any_changed = 1;
guard->confirmed_idx = guard_sl_idx;
}
} SMARTLIST_FOREACH_END(guard);
gs->next_confirmed_idx = smartlist_len(gs->confirmed_entry_guards);
if (any_changed) {
entry_guards_changed_for_guard_selection(gs);
}
}
/**
* Mark guard as a confirmed guard -- that is, one that we have
* connected to, and intend to use again.
*/
STATIC void
make_guard_confirmed(guard_selection_t *gs, entry_guard_t *guard)
{
if (BUG(guard->confirmed_on_date && guard->confirmed_idx >= 0))
return; // LCOV_EXCL_LINE
if (BUG(smartlist_contains(gs->confirmed_entry_guards, guard)))
return; // LCOV_EXCL_LINE
const int GUARD_LIFETIME = get_guard_lifetime_days() * 86400;
guard->confirmed_on_date = randomize_time(approx_time(), GUARD_LIFETIME/10);
log_info(LD_GUARD, "Marking %s as a confirmed guard (index %d)",
entry_guard_describe(guard),
gs->next_confirmed_idx);
guard->confirmed_idx = gs->next_confirmed_idx++;
smartlist_add(gs->confirmed_entry_guards, guard);
// This confirmed guard might kick something else out of the primary
// guards.
gs->primary_guards_up_to_date = 0;
entry_guards_changed_for_guard_selection(gs);
}
/**
* Recalculate the list of primary guards (the ones we'd prefer to use) from
* the filtered sample and the confirmed list.
*/
STATIC void
entry_guards_update_primary(guard_selection_t *gs)
{
/*XXXX prop271 consider splitting this function up. */
tor_assert(gs);
// prevent recursion. Recursion is potentially very bad here.
static int running = 0;
tor_assert(!running);
running = 1;
const int N_PRIMARY_GUARDS = get_n_primary_guards();
smartlist_t *new_primary_guards = smartlist_new();
smartlist_t *old_primary_guards = smartlist_new();
smartlist_add_all(old_primary_guards, gs->primary_entry_guards);
/* Set this flag now, to prevent the calls below from recursing. */
gs->primary_guards_up_to_date = 1;
/* First, can we fill it up with confirmed guards? */
SMARTLIST_FOREACH_BEGIN(gs->confirmed_entry_guards, entry_guard_t *, guard) {
if (smartlist_len(new_primary_guards) >= N_PRIMARY_GUARDS)
break;
if (! guard->is_filtered_guard)
continue;
guard->is_primary = 1;
smartlist_add(new_primary_guards, guard);
} SMARTLIST_FOREACH_END(guard);
/* Can we keep any older primary guards? First remove all the ones
* that we already kept. */
SMARTLIST_FOREACH_BEGIN(old_primary_guards, entry_guard_t *, guard) {
if (smartlist_contains(new_primary_guards, guard)) {
SMARTLIST_DEL_CURRENT_KEEPORDER(old_primary_guards, guard);
}
} SMARTLIST_FOREACH_END(guard);
/* Now add any that are still good. */
SMARTLIST_FOREACH_BEGIN(old_primary_guards, entry_guard_t *, guard) {
if (smartlist_len(new_primary_guards) >= N_PRIMARY_GUARDS)
break;
if (! guard->is_filtered_guard)
continue;
guard->is_primary = 1;
smartlist_add(new_primary_guards, guard);
SMARTLIST_DEL_CURRENT_KEEPORDER(old_primary_guards, guard);
} SMARTLIST_FOREACH_END(guard);
/* Mark the remaining previous primary guards as non-primary */
SMARTLIST_FOREACH_BEGIN(old_primary_guards, entry_guard_t *, guard) {
guard->is_primary = 0;
} SMARTLIST_FOREACH_END(guard);
/* Finally, fill out the list with sampled guards. */
while (smartlist_len(new_primary_guards) < N_PRIMARY_GUARDS) {
entry_guard_t *guard = sample_reachable_filtered_entry_guards(gs, NULL,
SAMPLE_EXCLUDE_CONFIRMED|
SAMPLE_EXCLUDE_PRIMARY|
SAMPLE_NO_UPDATE_PRIMARY);
if (!guard)
break;
guard->is_primary = 1;
smartlist_add(new_primary_guards, guard);
}
#if 1
/* Debugging. */
SMARTLIST_FOREACH(gs->sampled_entry_guards, entry_guard_t *, guard, {
tor_assert_nonfatal(
bool_eq(guard->is_primary,
smartlist_contains(new_primary_guards, guard)));
});
#endif
int any_change = 0;
if (smartlist_len(gs->primary_entry_guards) !=
smartlist_len(new_primary_guards)) {
any_change = 1;
} else {
SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, g) {
if (g != smartlist_get(new_primary_guards, g_sl_idx)) {
any_change = 1;
}
} SMARTLIST_FOREACH_END(g);
}
if (any_change) {
log_info(LD_GUARD, "Primary entry guards have changed. "
"New primary guard list is: ");
int n = smartlist_len(new_primary_guards);
SMARTLIST_FOREACH_BEGIN(new_primary_guards, entry_guard_t *, g) {
log_info(LD_GUARD, " %d/%d: %s%s%s",
g_sl_idx+1, n, entry_guard_describe(g),
g->confirmed_idx >= 0 ? " (confirmed)" : "",
g->is_filtered_guard ? "" : " (excluded by filter)");
} SMARTLIST_FOREACH_END(g);
}
smartlist_free(old_primary_guards);
smartlist_free(gs->primary_entry_guards);
gs->primary_entry_guards = new_primary_guards;
gs->primary_guards_up_to_date = 1;
running = 0;
}
/**
* Return the number of seconds after the last attempt at which we should
* retry a guard that has been failing since failing_since.
*/
static int
get_retry_schedule(time_t failing_since, time_t now,
int is_primary)
{
const unsigned SIX_HOURS = 6 * 3600;
const unsigned FOUR_DAYS = 4 * 86400;
const unsigned SEVEN_DAYS = 7 * 86400;
time_t tdiff;
if (now > failing_since) {
tdiff = now - failing_since;
} else {
tdiff = 0;
}
const struct {
time_t maximum; int primary_delay; int nonprimary_delay;
} delays[] = {
{ SIX_HOURS, 30*60, 1*60*60 },
{ FOUR_DAYS, 2*60*60, 4*60*60 },
{ SEVEN_DAYS, 4*60*60, 18*60*60 },
{ TIME_MAX, 9*60*60, 36*60*60 }
};
unsigned i;
for (i = 0; i < ARRAY_LENGTH(delays); ++i) {
if (tdiff <= delays[i].maximum) {
return is_primary ? delays[i].primary_delay : delays[i].nonprimary_delay;
}
}
/* LCOV_EXCL_START -- can't reach, since delays ends with TIME_MAX. */
tor_assert_nonfatal_unreached();
return 36*60*60;
/* LCOV_EXCL_STOP */
}
/**
* If guard is unreachable, consider whether enough time has passed
* to consider it maybe-reachable again.
*/
STATIC void
entry_guard_consider_retry(entry_guard_t *guard)
{
if (guard->is_reachable != GUARD_REACHABLE_NO)
return; /* No retry needed. */
const time_t now = approx_time();
const int delay =
get_retry_schedule(guard->failing_since, now, guard->is_primary);
const time_t last_attempt = guard->last_tried_to_connect;
if (BUG(last_attempt == 0) ||
now >= last_attempt + delay) {
/* We should mark this retriable. */
char tbuf[ISO_TIME_LEN+1];
format_local_iso_time(tbuf, last_attempt);
log_info(LD_GUARD, "Marked %s%sguard %s for possible retry, since we "
"haven't tried to use it since %s.",
guard->is_primary?"primary ":"",
guard->confirmed_idx>=0?"confirmed ":"",
entry_guard_describe(guard),
tbuf);
guard->is_reachable = GUARD_REACHABLE_MAYBE;
if (guard->is_filtered_guard)
guard->is_usable_filtered_guard = 1;
}
}
/** Tell the entry guards subsystem that we have confirmed that as of
* just now, we're on the internet. */
void
entry_guards_note_internet_connectivity(guard_selection_t *gs)
{
gs->last_time_on_internet = approx_time();
}
/**
* Get a guard for use with a circuit. Prefer to pick a running primary
* guard; then a non-pending running filtered confirmed guard; then a
* non-pending runnable filtered guard. Update the
* last_tried_to_connect time and the is_pending fields of the
* guard as appropriate. Set state_out to the new guard-state
* of the circuit.
*/
STATIC entry_guard_t *
select_entry_guard_for_circuit(guard_selection_t *gs,
const entry_guard_restriction_t *rst,
unsigned *state_out)
{
/*XXXX prop271 consider splitting this function up. */
tor_assert(gs);
tor_assert(state_out);
if (!gs->primary_guards_up_to_date)
entry_guards_update_primary(gs);
/* "If any entry in PRIMARY_GUARDS has {is_reachable} status of
or , return the first such guard." */
SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, guard) {
entry_guard_consider_retry(guard);
if (! entry_guard_obeys_restriction(guard, rst))
continue;
if (guard->is_reachable != GUARD_REACHABLE_NO) {
*state_out = GUARD_CIRC_STATE_USABLE_ON_COMPLETION;
guard->last_tried_to_connect = approx_time();
log_info(LD_GUARD, "Selected primary guard %s for circuit.",
entry_guard_describe(guard));
return guard;
}
} SMARTLIST_FOREACH_END(guard);
/* "Otherwise, if the ordered intersection of {CONFIRMED_GUARDS}
and {USABLE_FILTERED_GUARDS} is nonempty, return the first
entry in that intersection that has {is_pending} set to
false." */
SMARTLIST_FOREACH_BEGIN(gs->confirmed_entry_guards, entry_guard_t *, guard) {
if (guard->is_primary)
continue; /* we already considered this one. */
if (! entry_guard_obeys_restriction(guard, rst))
continue;
entry_guard_consider_retry(guard);
if (guard->is_usable_filtered_guard && ! guard->is_pending) {
guard->is_pending = 1;
guard->last_tried_to_connect = approx_time();
*state_out = GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD;
log_info(LD_GUARD, "No primary guards available. Selected confirmed "
"guard %s for circuit. Will try other guards before using "
"this circuit.",
entry_guard_describe(guard));
return guard;
}
} SMARTLIST_FOREACH_END(guard);
/* "Otherwise, if there is no such entry, select a member at
random from {USABLE_FILTERED_GUARDS}." */
{
entry_guard_t *guard;
guard = sample_reachable_filtered_entry_guards(gs,
rst,
SAMPLE_EXCLUDE_CONFIRMED |
SAMPLE_EXCLUDE_PRIMARY |
SAMPLE_EXCLUDE_PENDING);
if (guard == NULL) {
log_info(LD_GUARD, "Absolutely no sampled guards were available.");
return NULL;
}
guard->is_pending = 1;
guard->last_tried_to_connect = approx_time();
*state_out = GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD;
log_info(LD_GUARD, "No primary or confirmed guards available. Selected "
"random guard %s for circuit. Will try other guards before "
"using this circuit.",
entry_guard_describe(guard));
return guard;
}
}
/**
* Note that we failed to connect to or build circuits through guard.
* Use with a guard returned by select_entry_guard_for_circuit().
*/
STATIC void
entry_guards_note_guard_failure(guard_selection_t *gs,
entry_guard_t *guard)
{
tor_assert(gs);
guard->is_reachable = GUARD_REACHABLE_NO;
guard->is_usable_filtered_guard = 0;
guard->is_pending = 0;
if (guard->failing_since == 0)
guard->failing_since = approx_time();
log_info(LD_GUARD, "Recorded failure for %s%sguard %s",
guard->is_primary?"primary ":"",
guard->confirmed_idx>=0?"confirmed ":"",
entry_guard_describe(guard));
}
/**
* Called when the network comes up after having seemed to be down for
* a while: Mark the primary guards as maybe-reachable so that we'll
* try them again.
*/
STATIC void
mark_primary_guards_maybe_reachable(guard_selection_t *gs)
{
if (!gs->primary_guards_up_to_date)
entry_guards_update_primary(gs);
SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, guard) {
if (guard->is_reachable != GUARD_REACHABLE_NO)
continue;
/* Note that we do not clear failing_since: this guard is now only
* _maybe-reachable_. */
guard->is_reachable = GUARD_REACHABLE_MAYBE;
if (guard->is_filtered_guard)
guard->is_usable_filtered_guard = 1;
} SMARTLIST_FOREACH_END(guard);
}
/**
* Note that we successfully connected to, and built a circuit through
* guard. Given the old guard-state of the circuit in old_state,
* return the new guard-state of the circuit.
*
* Be aware: the circuit is only usable when its guard-state becomes
* GUARD_CIRC_STATE_COMPLETE.
**/
STATIC unsigned
entry_guards_note_guard_success(guard_selection_t *gs,
entry_guard_t *guard,
unsigned old_state)
{
tor_assert(gs);
/* Save this, since we're about to overwrite it. */
const time_t last_time_on_internet = gs->last_time_on_internet;
gs->last_time_on_internet = approx_time();
guard->is_reachable = GUARD_REACHABLE_YES;
guard->failing_since = 0;
guard->is_pending = 0;
if (guard->is_filtered_guard)
guard->is_usable_filtered_guard = 1;
if (guard->confirmed_idx < 0) {
make_guard_confirmed(gs, guard);
if (!gs->primary_guards_up_to_date)
entry_guards_update_primary(gs);
}
unsigned new_state;
if (old_state == GUARD_CIRC_STATE_USABLE_ON_COMPLETION) {
new_state = GUARD_CIRC_STATE_COMPLETE;
} else {
tor_assert_nonfatal(
old_state == GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD);
if (guard->is_primary) {
/* XXXX prop271 -- I don't actually like this logic. It seems to make us
* a little more susceptible to evil-ISP attacks. The mitigations I'm
* thinking of, however, aren't local to this point, so I'll leave it
* alone. */
/* This guard may have become primary by virtue of being confirmed.
If so, the circuit for it is now complete.
*/
new_state = GUARD_CIRC_STATE_COMPLETE;
} else {
new_state = GUARD_CIRC_STATE_WAITING_FOR_BETTER_GUARD;
}
if (last_time_on_internet + get_internet_likely_down_interval()
< approx_time()) {
mark_primary_guards_maybe_reachable(gs);
}
}
log_info(LD_GUARD, "Recorded success for %s%sguard %s",
guard->is_primary?"primary ":"",
guard->confirmed_idx>=0?"confirmed ":"",
entry_guard_describe(guard));
return new_state;
}
/**
* Helper: Return true iff a has higher priority than b.
*/
STATIC int
entry_guard_has_higher_priority(entry_guard_t *a, entry_guard_t *b)
{
tor_assert(a && b);
if (a == b)
return 0;
/* Confirmed is always better than unconfirmed; lower index better
than higher */
if (a->confirmed_idx < 0) {
if (b->confirmed_idx >= 0)
return 0;
} else {
if (b->confirmed_idx < 0)
return 1;
/* Lower confirmed_idx is better than higher. */
return (a->confirmed_idx < b->confirmed_idx);
}
/* If we reach this point, both are unconfirmed. If one is pending, it
* has higher priority. */
if (a->is_pending) {
if (! b->is_pending)
return 1;
/* Both are pending: earlier last_tried_connect wins. */
return a->last_tried_to_connect < b->last_tried_to_connect;
} else {
if (b->is_pending)
return 0;
/* Neither is pending: priorities are equal. */
return 0; // XXXX prop271 return a tristate instead?
}
}
/** Release all storage held in restriction */
static void
entry_guard_restriction_free(entry_guard_restriction_t *rst)
{
tor_free(rst);
}
/**
* Release all storage held in state.
*/
void
circuit_guard_state_free(circuit_guard_state_t *state)
{
if (!state)
return;
entry_guard_restriction_free(state->restrictions);
entry_guard_handle_free(state->guard);
tor_free(state);
}
/**
* Pick a suitable entry guard for a circuit in, and place that guard
* in *chosen_node_out. Set *guard_state_out to an opaque
* state object that will record whether the circuit is ready to be used
* or not. Return 0 on success; on failure, return -1.
*
* If a restriction is provided in rst, do not return any guards that
* violate it, and remember that restriction in guard_state_out for
* later use. (Takes ownership of the rst object.)
*/
int
entry_guard_pick_for_circuit(guard_selection_t *gs,
entry_guard_restriction_t *rst,
const node_t **chosen_node_out,
circuit_guard_state_t **guard_state_out)
{
tor_assert(gs);
tor_assert(chosen_node_out);
tor_assert(guard_state_out);
*chosen_node_out = NULL;
*guard_state_out = NULL;
unsigned state = 0;
entry_guard_t *guard = select_entry_guard_for_circuit(gs, rst, &state);
if (! guard)
goto fail;
if (BUG(state == 0))
goto fail;
const node_t *node = node_get_by_id(guard->identity);
// XXXX prop271 check Ed ID.
if (! node)
goto fail;
*chosen_node_out = node;
*guard_state_out = tor_malloc_zero(sizeof(circuit_guard_state_t));
(*guard_state_out)->guard = entry_guard_handle_new(guard);
(*guard_state_out)->state = state;
(*guard_state_out)->state_set_at = approx_time();
(*guard_state_out)->restrictions = rst;
return 0;
fail:
entry_guard_restriction_free(rst);
return -1;
}
/**
* Called by the circuit building module when a circuit has succeeded: informs
* the guards code that the guard in *guard_state_p is working, and
* advances the state of the guard module. On a GUARD_USABLE_NEVER return
* value, the circuit is broken and should not be used. On a GUARD_USABLE_NOW
* return value, the circuit is ready to use. On a GUARD_MAYBE_USABLE_LATER
* return value, the circuit should not be used until we find out whether
* preferred guards will work for us.
*/
guard_usable_t
entry_guard_succeeded(circuit_guard_state_t **guard_state_p)
{
if (get_options()->UseDeprecatedGuardAlgorithm)
return GUARD_USABLE_NOW;
if (BUG(*guard_state_p == NULL))
return GUARD_USABLE_NEVER;
entry_guard_t *guard = entry_guard_handle_get((*guard_state_p)->guard);
if (! guard || BUG(guard->in_selection == NULL))
return GUARD_USABLE_NEVER;
unsigned newstate =
entry_guards_note_guard_success(guard->in_selection, guard,
(*guard_state_p)->state);
(*guard_state_p)->state = newstate;
(*guard_state_p)->state_set_at = approx_time();
if (newstate == GUARD_CIRC_STATE_COMPLETE) {
return GUARD_USABLE_NOW;
} else {
return GUARD_MAYBE_USABLE_LATER;
}
}
/** Cancel the selection of *guard_state_p without declaring
* success or failure. It is safe to call this function if success or
* failure _has_ already been declared. */
void
entry_guard_cancel(circuit_guard_state_t **guard_state_p)
{
if (get_options()->UseDeprecatedGuardAlgorithm)
return;
if (BUG(*guard_state_p == NULL))
return;
entry_guard_t *guard = entry_guard_handle_get((*guard_state_p)->guard);
if (! guard)
return;
/* XXXX prop271 -- last_tried_to_connect_at will be erroneous here, but this
* function will only get called in "bug" cases anyway. */
guard->is_pending = 0;
circuit_guard_state_free(*guard_state_p);
*guard_state_p = NULL;
}
/**
* Called by the circuit building module when a circuit has succeeded:
* informs the guards code that the guard in *guard_state_p is
* not working, and advances the state of the guard module.
*/
void
entry_guard_failed(circuit_guard_state_t **guard_state_p)
{
if (get_options()->UseDeprecatedGuardAlgorithm)
return;
if (BUG(*guard_state_p == NULL))
return;
entry_guard_t *guard = entry_guard_handle_get((*guard_state_p)->guard);
if (! guard || BUG(guard->in_selection == NULL))
return;
entry_guards_note_guard_failure(guard->in_selection, guard);
(*guard_state_p)->state = GUARD_CIRC_STATE_DEAD;
(*guard_state_p)->state_set_at = approx_time();
}
/**
* Run the entry_guard_failed() function on every circuit that is
* pending on chan.
*/
void
entry_guard_chan_failed(channel_t *chan)
{
if (!chan)
return;
if (get_options()->UseDeprecatedGuardAlgorithm)
return;
smartlist_t *pending = smartlist_new();
circuit_get_all_pending_on_channel(pending, chan);
SMARTLIST_FOREACH_BEGIN(pending, circuit_t *, circ) {
if (!CIRCUIT_IS_ORIGIN(circ))
continue;
origin_circuit_t *origin_circ = TO_ORIGIN_CIRCUIT(circ);
entry_guard_failed(&origin_circ->guard_state);
} SMARTLIST_FOREACH_END(circ);
smartlist_free(pending);
}
/**
* Return true iff every primary guard in gs is believed to
* be unreachable.
*/
STATIC int
entry_guards_all_primary_guards_are_down(guard_selection_t *gs)
{
tor_assert(gs);
if (!gs->primary_guards_up_to_date)
entry_guards_update_primary(gs);
SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, guard) {
entry_guard_consider_retry(guard);
if (guard->is_reachable != GUARD_REACHABLE_NO)
return 0;
} SMARTLIST_FOREACH_END(guard);
return 1;
}
/** Wrapper for entry_guard_has_higher_priority that compares the
* guard-priorities of a pair of circuits.
*
* If a restriction is provided in rst, then do not consider
* a to have higher priority if it violates the restriction.
*/
static int
circ_state_has_higher_priority(origin_circuit_t *a,
const entry_guard_restriction_t *rst,
origin_circuit_t *b)
{
circuit_guard_state_t *state_a = origin_circuit_get_guard_state(a);
circuit_guard_state_t *state_b = origin_circuit_get_guard_state(b);
tor_assert(state_a);
tor_assert(state_b);
entry_guard_t *guard_a = entry_guard_handle_get(state_a->guard);
entry_guard_t *guard_b = entry_guard_handle_get(state_b->guard);
if (! guard_a) {
/* Unknown guard -- never higher priority. */
return 0;
} else if (! guard_b) {
/* Known guard -- higher priority than any unknown guard. */
return 1;
} else if (! entry_guard_obeys_restriction(guard_a, rst)) {
/* Restriction violated; guard_a cannot have higher priority. */
return 0;
} else {
/* Both known -- compare.*/
return entry_guard_has_higher_priority(guard_a, guard_b);
}
}
/**
* Look at all of the origin_circuit_t * objects in all_circuits_in,
* and see if any of them that were previously not ready to use for
* guard-related reasons are now ready to use. Place those circuits
* in newly_complete_out, and mark them COMPLETE.
*
* Return 1 if we upgraded any circuits, and 0 otherwise.
*/
int
entry_guards_upgrade_waiting_circuits(guard_selection_t *gs,
const smartlist_t *all_circuits_in,
smartlist_t *newly_complete_out)
{
tor_assert(gs);
tor_assert(all_circuits_in);
tor_assert(newly_complete_out);
if (! entry_guards_all_primary_guards_are_down(gs)) {
/* We only upgrade a waiting circuit if the primary guards are all
* down. */
log_debug(LD_GUARD, "Considered upgrading guard-stalled circuits, "
"but not all primary guards were definitely down.");
return 0;
}
int n_waiting = 0;
int n_complete = 0;
int n_complete_blocking = 0;
origin_circuit_t *best_waiting_circuit = NULL;
smartlist_t *all_circuits = smartlist_new();
SMARTLIST_FOREACH_BEGIN(all_circuits_in, origin_circuit_t *, circ) {
// We filter out circuits that aren't ours, or which we can't
// reason about.
circuit_guard_state_t *state = origin_circuit_get_guard_state(circ);
if (state == NULL)
continue;
entry_guard_t *guard = entry_guard_handle_get(state->guard);
if (!guard || guard->in_selection != gs)
continue;
smartlist_add(all_circuits, circ);
} SMARTLIST_FOREACH_END(circ);
SMARTLIST_FOREACH_BEGIN(all_circuits, origin_circuit_t *, circ) {
circuit_guard_state_t *state = origin_circuit_get_guard_state(circ);
if BUG((state == NULL))
continue;
if (state->state == GUARD_CIRC_STATE_WAITING_FOR_BETTER_GUARD) {
++n_waiting;
if (! best_waiting_circuit ||
circ_state_has_higher_priority(circ, NULL, best_waiting_circuit)) {
best_waiting_circuit = circ;
}
}
} SMARTLIST_FOREACH_END(circ);
if (! best_waiting_circuit) {
log_debug(LD_GUARD, "Considered upgrading guard-stalled circuits, "
"but didn't find any.");
goto no_change;
}
/* We'll need to keep track of what restrictions were used when picking this
* circuit, so that we don't allow any circuit without those restrictions to
* block it. */
const entry_guard_restriction_t *rst_on_best_waiting =
origin_circuit_get_guard_state(best_waiting_circuit)->restrictions;
/* First look at the complete circuits: Do any block this circuit? */
SMARTLIST_FOREACH_BEGIN(all_circuits, origin_circuit_t *, circ) {
circuit_guard_state_t *state = origin_circuit_get_guard_state(circ);
if BUG((state == NULL))
continue;
if (state->state != GUARD_CIRC_STATE_COMPLETE)
continue;
++n_complete;
if (circ_state_has_higher_priority(circ, rst_on_best_waiting,
best_waiting_circuit))
++n_complete_blocking;
} SMARTLIST_FOREACH_END(circ);
if (n_complete_blocking) {
/* "If any circuit is , then do not use any
or circuits
circuits whose guards have lower priority." */
log_debug(LD_GUARD, "Considered upgrading guard-stalled circuits: found "
"%d complete and %d guard-stalled. At least one complete "
"circuit had higher priority, so not upgrading.",
n_complete, n_waiting);
goto no_change;
}
/* "If any circuit is , and every currently
{is_pending} circuit whose guard has higher priority has been in
state for at least
{NONPRIMARY_GUARD_CONNECT_TIMEOUT} seconds, and all primary guards
have reachable status of , then call that circuit ."
XXXX --- prop271 deviation. there's no such thing in the spec as
an {is_pending circuit}; fix the spec.
*/
int n_blockers_found = 0;
const time_t state_set_at_cutoff =
approx_time() - get_nonprimary_guard_connect_timeout();
SMARTLIST_FOREACH_BEGIN(all_circuits, origin_circuit_t *, circ) {
circuit_guard_state_t *state = origin_circuit_get_guard_state(circ);
if (BUG(state == NULL))
continue;
if (state->state != GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD)
continue;
if (state->state_set_at <= state_set_at_cutoff)
continue;
if (circ_state_has_higher_priority(circ, rst_on_best_waiting,
best_waiting_circuit))
++n_blockers_found;
} SMARTLIST_FOREACH_END(circ);
if (n_blockers_found) {
log_debug(LD_GUARD, "Considered upgrading guard-stalled circuits: found "
"%d guard-stalled, but %d pending circuit(s) had higher "
"guard priority, so not upgrading.",
n_waiting, n_blockers_found);
goto no_change;
}
/* Okay. We have a best waiting circuit, and we aren't waiting for
anything better. Add all circuits with that priority to the
list, and call them COMPLETE. */
int n_succeeded = 0;
SMARTLIST_FOREACH_BEGIN(all_circuits, origin_circuit_t *, circ) {
circuit_guard_state_t *state = origin_circuit_get_guard_state(circ);
if (BUG(state == NULL))
continue;
if (circ != best_waiting_circuit && rst_on_best_waiting) {
/* Can't upgrade other circ with same priority as best; might
be blocked. */
continue;
}
if (state->state != GUARD_CIRC_STATE_WAITING_FOR_BETTER_GUARD)
continue;
if (circ_state_has_higher_priority(best_waiting_circuit, NULL, circ))
continue;
state->state = GUARD_CIRC_STATE_COMPLETE;
state->state_set_at = approx_time();
smartlist_add(newly_complete_out, circ);
++n_succeeded;
} SMARTLIST_FOREACH_END(circ);
log_info(LD_GUARD, "Considered upgrading guard-stalled circuits: found "
"%d guard-stalled, %d complete. %d of the guard-stalled "
"circuit(s) had high enough priority to upgrade.",
n_waiting, n_complete, n_succeeded);
tor_assert_nonfatal(n_succeeded >= 1);
smartlist_free(all_circuits);
return 1;
no_change:
smartlist_free(all_circuits);
return 0;
}
/**
* Return true iff the circuit whose state is guard_state should
* expire.
*/
int
entry_guard_state_should_expire(circuit_guard_state_t *guard_state)
{
if (guard_state == NULL)
return 0;
const time_t expire_if_waiting_since =
approx_time() - get_nonprimary_guard_idle_timeout();
return (guard_state->state == GUARD_CIRC_STATE_WAITING_FOR_BETTER_GUARD
&& guard_state->state_set_at < expire_if_waiting_since);
}
/**
* Update all derived pieces of the guard selection state in gs.
* Return true iff we should stop using all previously generated circuits.
*/
int
entry_guards_update_all(guard_selection_t *gs)
{
sampled_guards_update_from_consensus(gs);
entry_guards_update_filtered_sets(gs);
entry_guards_update_confirmed(gs);
entry_guards_update_primary(gs);
return 0;
}
/**
* Return a newly allocated string for encoding the persistent parts of
* guard to the state file.
*/
STATIC char *
entry_guard_encode_for_state(entry_guard_t *guard)
{
/*
* The meta-format we use is K=V K=V K=V... where K can be any
* characters excepts space and =, and V can be any characters except
* space. The order of entries is not allowed to matter.
* Unrecognized K=V entries are persisted; recognized but erroneous
* entries are corrected.
*/
smartlist_t *result = smartlist_new();
char tbuf[ISO_TIME_LEN+1];
tor_assert(guard);
smartlist_add_asprintf(result, "in=%s", guard->selection_name);
smartlist_add_asprintf(result, "rsa_id=%s",
hex_str(guard->identity, DIGEST_LEN));
if (guard->bridge_addr) {
smartlist_add_asprintf(result, "bridge_addr=%s:%d",
fmt_and_decorate_addr(&guard->bridge_addr->addr),
guard->bridge_addr->port);
}
if (strlen(guard->nickname) && is_legal_nickname(guard->nickname)) {
smartlist_add_asprintf(result, "nickname=%s", guard->nickname);
}
format_iso_time_nospace(tbuf, guard->sampled_on_date);
smartlist_add_asprintf(result, "sampled_on=%s", tbuf);
if (guard->sampled_by_version) {
smartlist_add_asprintf(result, "sampled_by=%s",
guard->sampled_by_version);
}
if (guard->unlisted_since_date > 0) {
format_iso_time_nospace(tbuf, guard->unlisted_since_date);
smartlist_add_asprintf(result, "unlisted_since=%s", tbuf);
}
smartlist_add_asprintf(result, "listed=%d",
(int)guard->currently_listed);
if (guard->confirmed_idx >= 0) {
format_iso_time_nospace(tbuf, guard->confirmed_on_date);
smartlist_add_asprintf(result, "confirmed_on=%s", tbuf);
smartlist_add_asprintf(result, "confirmed_idx=%d", guard->confirmed_idx);
}
const double EPSILON = 1.0e-6;
/* Make a copy of the pathbias object, since we will want to update
some of them */
guard_pathbias_t *pb = tor_memdup(&guard->pb, sizeof(*pb));
pb->use_successes = pathbias_get_use_success_count(guard);
pb->successful_circuits_closed = pathbias_get_close_success_count(guard);
#define PB_FIELD(field) do { \
if (pb->field >= EPSILON) { \
smartlist_add_asprintf(result, "pb_" #field "=%f", pb->field); \
} \
} while (0)
PB_FIELD(use_attempts);
PB_FIELD(use_successes);
PB_FIELD(circ_attempts);
PB_FIELD(circ_successes);
PB_FIELD(successful_circuits_closed);
PB_FIELD(collapsed_circuits);
PB_FIELD(unusable_circuits);
PB_FIELD(timeouts);
tor_free(pb);
#undef PB_FIELD
if (guard->extra_state_fields)
smartlist_add_strdup(result, guard->extra_state_fields);
char *joined = smartlist_join_strings(result, " ", 0, NULL);
SMARTLIST_FOREACH(result, char *, cp, tor_free(cp));
smartlist_free(result);
return joined;
}
/**
* Given a string generated by entry_guard_encode_for_state(), parse it
* (if possible) and return an entry_guard_t object for it. Return NULL
* on complete failure.
*/
STATIC entry_guard_t *
entry_guard_parse_from_state(const char *s)
{
/* Unrecognized entries get put in here. */
smartlist_t *extra = smartlist_new();
/* These fields get parsed from the string. */
char *in = NULL;
char *rsa_id = NULL;
char *nickname = NULL;
char *sampled_on = NULL;
char *sampled_by = NULL;
char *unlisted_since = NULL;
char *listed = NULL;
char *confirmed_on = NULL;
char *confirmed_idx = NULL;
char *bridge_addr = NULL;
// pathbias
char *pb_use_attempts = NULL;
char *pb_use_successes = NULL;
char *pb_circ_attempts = NULL;
char *pb_circ_successes = NULL;
char *pb_successful_circuits_closed = NULL;
char *pb_collapsed_circuits = NULL;
char *pb_unusable_circuits = NULL;
char *pb_timeouts = NULL;
/* Split up the entries. Put the ones we know about in strings and the
* rest in "extra". */
{
smartlist_t *entries = smartlist_new();
strmap_t *vals = strmap_new(); // Maps keyword to location
#define FIELD(f) \
strmap_set(vals, #f, &f);
FIELD(in);
FIELD(rsa_id);
FIELD(nickname);
FIELD(sampled_on);
FIELD(sampled_by);
FIELD(unlisted_since);
FIELD(listed);
FIELD(confirmed_on);
FIELD(confirmed_idx);
FIELD(bridge_addr);
FIELD(pb_use_attempts);
FIELD(pb_use_successes);
FIELD(pb_circ_attempts);
FIELD(pb_circ_successes);
FIELD(pb_successful_circuits_closed);
FIELD(pb_collapsed_circuits);
FIELD(pb_unusable_circuits);
FIELD(pb_timeouts);
#undef FIELD
smartlist_split_string(entries, s, " ",
SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
SMARTLIST_FOREACH_BEGIN(entries, char *, entry) {
const char *eq = strchr(entry, '=');
if (!eq) {
smartlist_add(extra, entry);
continue;
}
char *key = tor_strndup(entry, eq-entry);
char **target = strmap_get(vals, key);
if (target == NULL || *target != NULL) {
/* unrecognized or already set */
smartlist_add(extra, entry);
tor_free(key);
continue;
}
*target = tor_strdup(eq+1);
tor_free(key);
tor_free(entry);
} SMARTLIST_FOREACH_END(entry);
smartlist_free(entries);
strmap_free(vals, NULL);
}
entry_guard_t *guard = tor_malloc_zero(sizeof(entry_guard_t));
guard->is_persistent = 1;
if (in == NULL) {
log_warn(LD_CIRC, "Guard missing 'in' field");
goto err;
}
guard->selection_name = in;
in = NULL;
if (rsa_id == NULL) {
log_warn(LD_CIRC, "Guard missing RSA ID field");
goto err;
}
/* Process the identity and nickname. */
if (base16_decode(guard->identity, sizeof(guard->identity),
rsa_id, strlen(rsa_id)) != DIGEST_LEN) {
log_warn(LD_CIRC, "Unable to decode guard identity %s", escaped(rsa_id));
goto err;
}
if (nickname) {
strlcpy(guard->nickname, nickname, sizeof(guard->nickname));
} else {
guard->nickname[0]='$';
base16_encode(guard->nickname+1, sizeof(guard->nickname)-1,
guard->identity, DIGEST_LEN);
}
if (bridge_addr) {
tor_addr_port_t res;
memset(&res, 0, sizeof(res));
int r = tor_addr_port_parse(LOG_WARN, bridge_addr,
&res.addr, &res.port, -1);
if (r == 0)
guard->bridge_addr = tor_memdup(&res, sizeof(res));
/* On error, we already warned. */
}
/* Process the various time fields. */
#define HANDLE_TIME(field) do { \
if (field) { \
int r = parse_iso_time_nospace(field, &field ## _time); \
if (r < 0) { \
log_warn(LD_CIRC, "Unable to parse %s %s from guard", \
#field, escaped(field)); \
field##_time = -1; \
} \
} \
} while (0)
time_t sampled_on_time = 0;
time_t unlisted_since_time = 0;
time_t confirmed_on_time = 0;
HANDLE_TIME(sampled_on);
HANDLE_TIME(unlisted_since);
HANDLE_TIME(confirmed_on);
if (sampled_on_time <= 0)
sampled_on_time = approx_time();
if (unlisted_since_time < 0)
unlisted_since_time = 0;
if (confirmed_on_time < 0)
confirmed_on_time = 0;
#undef HANDLE_TIME
guard->sampled_on_date = sampled_on_time;
guard->unlisted_since_date = unlisted_since_time;
guard->confirmed_on_date = confirmed_on_time;
/* Take sampled_by_version verbatim. */
guard->sampled_by_version = sampled_by;
sampled_by = NULL; /* prevent free */
// XXXX -- prop271 spec deviation -- we do not require sampled_by_version
/* Listed is a boolean */
if (listed && strcmp(listed, "0"))
guard->currently_listed = 1;
/* The index is a nonnegative integer. */
guard->confirmed_idx = -1;
if (confirmed_idx) {
int ok=1;
long idx = tor_parse_long(confirmed_idx, 10, 0, INT_MAX, &ok, NULL);
if (! ok) {
log_warn(LD_GUARD, "Guard has invalid confirmed_idx %s",
escaped(confirmed_idx));
} else {
guard->confirmed_idx = (int)idx;
}
}
/* Anything we didn't recognize gets crammed together */
if (smartlist_len(extra) > 0) {
guard->extra_state_fields = smartlist_join_strings(extra, " ", 0, NULL);
}
/* initialize non-persistent fields */
guard->is_reachable = GUARD_REACHABLE_MAYBE;
#define PB_FIELD(field) \
do { \
if (pb_ ## field) { \
int ok = 1; \
double r = tor_parse_double(pb_ ## field, 0.0, 1e9, &ok, NULL); \
if (! ok) { \
log_warn(LD_CIRC, "Guard has invalid pb_%s %s", \
#field, pb_ ## field); \
} else { \
guard->pb.field = r; \
} \
} \
} while (0)
PB_FIELD(use_attempts);
PB_FIELD(use_successes);
PB_FIELD(circ_attempts);
PB_FIELD(circ_successes);
PB_FIELD(successful_circuits_closed);
PB_FIELD(collapsed_circuits);
PB_FIELD(unusable_circuits);
PB_FIELD(timeouts);
#undef PB_FIELD
pathbias_check_use_success_count(guard);
pathbias_check_close_success_count(guard);
/* We update everything on this guard later, after we've parsed
* everything. */
goto done;
err:
// only consider it an error if the guard state was totally unparseable.
entry_guard_free(guard);
guard = NULL;
done:
tor_free(in);
tor_free(rsa_id);
tor_free(nickname);
tor_free(sampled_on);
tor_free(sampled_by);
tor_free(unlisted_since);
tor_free(listed);
tor_free(confirmed_on);
tor_free(confirmed_idx);
tor_free(bridge_addr);
tor_free(pb_use_attempts);
tor_free(pb_use_successes);
tor_free(pb_circ_attempts);
tor_free(pb_circ_successes);
tor_free(pb_successful_circuits_closed);
tor_free(pb_collapsed_circuits);
tor_free(pb_unusable_circuits);
tor_free(pb_timeouts);
SMARTLIST_FOREACH(extra, char *, cp, tor_free(cp));
smartlist_free(extra);
return guard;
}
/**
* Replace the Guards entries in state with a list of all our
* non-legacy sampled guards.
*/
static void
entry_guards_update_guards_in_state(or_state_t *state)
{
if (!guard_contexts)
return;
config_line_t *lines = NULL;
config_line_t **nextline = &lines;
SMARTLIST_FOREACH_BEGIN(guard_contexts, guard_selection_t *, gs) {
if (!strcmp(gs->name, "legacy"))
continue; /* This is encoded differently. */
SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
if (guard->is_persistent == 0)
continue;
*nextline = tor_malloc_zero(sizeof(config_line_t));
(*nextline)->key = tor_strdup("Guard");
(*nextline)->value = entry_guard_encode_for_state(guard);
nextline = &(*nextline)->next;
} SMARTLIST_FOREACH_END(guard);
} SMARTLIST_FOREACH_END(gs);
config_free_lines(state->Guard);
state->Guard = lines;
}
/**
* Replace our non-legacy sampled guards from the Guards entries in
* state. Return 0 on success, -1 on failure. (If set is
* true, replace nothing -- only check whether replacing would work.)
*/
static int
entry_guards_load_guards_from_state(or_state_t *state, int set)
{
const config_line_t *line = state->Guard;
int n_errors = 0;
if (!guard_contexts)
guard_contexts = smartlist_new();
/* Wipe all our existing guard info. (we shouldn't have any, but
* let's be safe.) */
if (set) {
SMARTLIST_FOREACH_BEGIN(guard_contexts, guard_selection_t *, gs) {
if (!strcmp(gs->name, "legacy"))
continue;
guard_selection_free(gs);
if (curr_guard_context == gs)
curr_guard_context = NULL;
SMARTLIST_DEL_CURRENT(guard_contexts, gs);
} SMARTLIST_FOREACH_END(gs);
}
for ( ; line != NULL; line = line->next) {
entry_guard_t *guard = entry_guard_parse_from_state(line->value);
if (guard == NULL) {
++n_errors;
continue;
}
tor_assert(guard->selection_name);
if (!strcmp(guard->selection_name, "legacy")) {
++n_errors;
entry_guard_free(guard);
continue;
}
if (set) {
guard_selection_t *gs;
gs = get_guard_selection_by_name(guard->selection_name,
GS_TYPE_INFER, 1);
tor_assert(gs);
smartlist_add(gs->sampled_entry_guards, guard);
guard->in_selection = gs;
} else {
entry_guard_free(guard);
}
}
if (set) {
SMARTLIST_FOREACH_BEGIN(guard_contexts, guard_selection_t *, gs) {
if (!strcmp(gs->name, "legacy"))
continue;
entry_guards_update_all(gs);
} SMARTLIST_FOREACH_END(gs);
}
return n_errors ? -1 : 0;
}
/* XXXXX ----------------------------------------------- */
/* XXXXX prop271 ----- end of new-for-prop271 code ----- */
/* XXXXX ----------------------------------------------- */
/**
* @name Constants for old (pre-prop271) guard selection algorithm.
*/
/**@{*/
/* Default number of entry guards in the case where the NumEntryGuards
* consensus parameter is not set */
#define DEFAULT_N_GUARDS 1
/* Minimum and maximum number of entry guards (in case the NumEntryGuards
* consensus parameter is set). */
#define MIN_N_GUARDS 1
#define MAX_N_GUARDS 10
/** Largest amount that we'll backdate chosen_on_date */
#define CHOSEN_ON_DATE_SLOP (30*86400)
/** How long (in seconds) do we allow an entry guard to be nonfunctional,
* unlisted, excluded, or otherwise nonusable before we give up on it? */
#define ENTRY_GUARD_REMOVE_AFTER (30*24*60*60)
/**}@*/
/**
* @name Networkstatus parameters for old (pre-prop271) guard selection
*/
/**@}*/
/** Choose how many entry guards or directory guards we'll use. If
* for_directory is true, we return how many directory guards to
* use; else we return how many entry guards to use. */
STATIC int
decide_num_guards(const or_options_t *options, int for_directory)
{
if (for_directory) {
int answer;
if (options->NumDirectoryGuards != 0)
return options->NumDirectoryGuards;
answer = networkstatus_get_param(NULL, "NumDirectoryGuards", 0, 0, 10);
if (answer) /* non-zero means use the consensus value */
return answer;
}
if (options->NumEntryGuards)
return options->NumEntryGuards;
/* Use the value from the consensus, or 3 if no guidance. */
return networkstatus_get_param(NULL, "NumEntryGuards", DEFAULT_N_GUARDS,
MIN_N_GUARDS, MAX_N_GUARDS);
}
/** Check whether the entry guard e is usable, given the directory
* authorities' opinion about the router (stored in ri) and the user's
* configuration (in options). Set e->bad_since
* accordingly. Return true iff the entry guard's status changes.
*
* If it's not usable, set *reason to a static string explaining why.
*/
static int
entry_guard_set_status(entry_guard_t *e, const node_t *node,
time_t now, const or_options_t *options,
const char **reason)
{
char buf[HEX_DIGEST_LEN+1];
int changed = 0;
*reason = NULL;
/* Do we want to mark this guard as bad? */
if (!node)
*reason = "unlisted";
else if (!node->is_running)
*reason = "down";
else if (options->UseBridges && (!node->ri ||
node->ri->purpose != ROUTER_PURPOSE_BRIDGE))
*reason = "not a bridge";
else if (options->UseBridges && !node_is_a_configured_bridge(node))
*reason = "not a configured bridge";
else if (!options->UseBridges && !node->is_possible_guard &&
!routerset_contains_node(options->EntryNodes,node))
*reason = "not recommended as a guard";
else if (routerset_contains_node(options->ExcludeNodes, node))
*reason = "excluded";
/* We only care about OR connection connectivity for entry guards. */
else if (!fascist_firewall_allows_node(node, FIREWALL_OR_CONNECTION, 0))
*reason = "unreachable by config";
else if (e->pb.path_bias_disabled)
*reason = "path-biased";
if (*reason && ! e->bad_since) {
/* Router is newly bad. */
base16_encode(buf, sizeof(buf), e->identity, DIGEST_LEN);
log_info(LD_CIRC, "Entry guard %s (%s) is %s: marking as unusable.",
e->nickname, buf, *reason);
e->bad_since = now;
control_event_guard(e->nickname, e->identity, "BAD");
changed = 1;
} else if (!*reason && e->bad_since) {
/* There's nothing wrong with the router any more. */
base16_encode(buf, sizeof(buf), e->identity, DIGEST_LEN);
log_info(LD_CIRC, "Entry guard %s (%s) is no longer unusable: "
"marking as ok.", e->nickname, buf);
e->bad_since = 0;
control_event_guard(e->nickname, e->identity, "GOOD");
changed = 1;
}
if (node) {
int is_dir = node_is_dir(node);
if (options->UseBridges && node_is_a_configured_bridge(node))
is_dir = 1;
if (e->is_dir_cache != is_dir) {
e->is_dir_cache = is_dir;
changed = 1;
}
}
return changed;
}
/** Return true iff enough time has passed since we last tried to connect
* to the unreachable guard e that we're willing to try again. */
STATIC int
entry_is_time_to_retry(const entry_guard_t *e, time_t now)
{
struct guard_retry_period_s {
time_t period_duration;
time_t interval_during_period;
};
struct guard_retry_period_s periods[] = {
{ 6*60*60, 60*60 }, /* For first 6 hrs., retry hourly; */
{ 3*24*60*60, 4*60*60 }, /* Then retry every 4 hrs. until the
3-day mark; */
{ 7*24*60*60, 18*60*60 }, /* After 3 days, retry every 18 hours until
1 week mark. */
{ TIME_MAX, 36*60*60 } /* After 1 week, retry every 36 hours. */
};
time_t ith_deadline_for_retry;
time_t unreachable_for;
unsigned i;
if (e->last_attempted < e->unreachable_since)
return 1;
unreachable_for = now - e->unreachable_since;
for (i = 0; i < ARRAY_LENGTH(periods); i++) {
if (unreachable_for <= periods[i].period_duration) {
ith_deadline_for_retry = e->last_attempted +
periods[i].interval_during_period;
return (now > ith_deadline_for_retry);
}
}
return 0;
}
/** Return the node corresponding to e, if e is
* working well enough that we are willing to use it as an entry
* right now. (Else return NULL.) In particular, it must be
* - Listed as either up or never yet contacted;
* - Present in the routerlist;
* - Listed as 'stable' or 'fast' by the current dirserver consensus,
* if demanded by need_uptime or need_capacity
* (unless it's a configured EntryNode);
* - Allowed by our current ReachableORAddresses config option; and
* - Currently thought to be reachable by us (unless assume_reachable
* is true).
*
* If the answer is no, set *msg to an explanation of why.
*
* If need_descriptor is true, only return the node if we currently have
* a descriptor (routerinfo or microdesc) for it.
*/
STATIC const node_t *
entry_is_live(const entry_guard_t *e, entry_is_live_flags_t flags,
const char **msg)
{
const node_t *node;
const or_options_t *options = get_options();
int need_uptime = (flags & ENTRY_NEED_UPTIME) != 0;
int need_capacity = (flags & ENTRY_NEED_CAPACITY) != 0;
const int assume_reachable = (flags & ENTRY_ASSUME_REACHABLE) != 0;
const int need_descriptor = (flags & ENTRY_NEED_DESCRIPTOR) != 0;
tor_assert(msg);
if (e->pb.path_bias_disabled) {
*msg = "path-biased";
return NULL;
}
if (e->bad_since) {
*msg = "bad";
return NULL;
}
/* no good if it's unreachable, unless assume_unreachable or can_retry. */
if (!assume_reachable && !e->can_retry &&
e->unreachable_since && !entry_is_time_to_retry(e, time(NULL))) {
*msg = "unreachable";
return NULL;
}
node = node_get_by_id(e->identity);
if (!node) {
*msg = "no node info";
return NULL;
}
if (need_descriptor && !node_has_descriptor(node)) {
*msg = "no descriptor";
return NULL;
}
if (get_options()->UseBridges) {
if (node_get_purpose(node) != ROUTER_PURPOSE_BRIDGE) {
*msg = "not a bridge";
return NULL;
}
if (!node_is_a_configured_bridge(node)) {
*msg = "not a configured bridge";
return NULL;
}
} else { /* !get_options()->UseBridges */
if (node_get_purpose(node) != ROUTER_PURPOSE_GENERAL) {
*msg = "not general-purpose";
return NULL;
}
}
if (routerset_contains_node(options->EntryNodes, node)) {
/* they asked for it, they get it */
need_uptime = need_capacity = 0;
}
if (node_is_unreliable(node, need_uptime, need_capacity, 0)) {
*msg = "not fast/stable";
return NULL;
}
if (!fascist_firewall_allows_node(node, FIREWALL_OR_CONNECTION, 0)) {
*msg = "unreachable by config";
return NULL;
}
return node;
}
/** Return the number of entry guards that we think are usable, in the
* context of the given guard_selection_t */
int
num_live_entry_guards_for_guard_selection(guard_selection_t *gs,
int for_directory)
{
int n = 0;
const char *msg;
tor_assert(gs != NULL);
/* Set the entry node attributes we are interested in. */
entry_is_live_flags_t entry_flags = ENTRY_NEED_CAPACITY;
if (!for_directory) {
entry_flags |= ENTRY_NEED_DESCRIPTOR;
}
if (!(gs->chosen_entry_guards)) {
return 0;
}
SMARTLIST_FOREACH_BEGIN(gs->chosen_entry_guards, entry_guard_t *, entry) {
if (for_directory && !entry->is_dir_cache)
continue;
if (entry_is_live(entry, entry_flags, &msg))
++n;
} SMARTLIST_FOREACH_END(entry);
return n;
}
/** Return the number of entry guards that we think are usable, for the
* default guard selection */
int
num_live_entry_guards(int for_directory)
{
return num_live_entry_guards_for_guard_selection(
get_guard_selection_info(), for_directory);
}
/** If digest matches the identity of any node in the
* entry_guards list for the provided guard selection state,
return that node. Else return NULL. */
entry_guard_t *
entry_guard_get_by_id_digest_for_guard_selection(guard_selection_t *gs,
const char *digest)
{
tor_assert(gs != NULL);
SMARTLIST_FOREACH(gs->sampled_entry_guards, entry_guard_t *, entry,
if (tor_memeq(digest, entry->identity, DIGEST_LEN))
return entry;
);
SMARTLIST_FOREACH(gs->chosen_entry_guards, entry_guard_t *, entry,
if (tor_memeq(digest, entry->identity, DIGEST_LEN))
return entry;
);
return NULL;
}
/** Return the node_t associated with a single entry_guard_t. May
* return NULL if the guard is not currently in the consensus. */
const node_t *
entry_guard_find_node(const entry_guard_t *guard)
{
tor_assert(guard);
return node_get_by_id(guard->identity);
}
/** If digest matches the identity of any node in the
* entry_guards list for the default guard selection state,
return that node. Else return NULL. */
entry_guard_t *
entry_guard_get_by_id_digest(const char *digest)
{
return entry_guard_get_by_id_digest_for_guard_selection(
get_guard_selection_info(), digest);
}
/** Dump a description of our list of entry guards in the given guard
* selection context to the log at level severity. */
static void
log_entry_guards_for_guard_selection(guard_selection_t *gs, int severity)
{
smartlist_t *elements = smartlist_new();
char *s;
/*
* TODO this should probably log more info about prop-271 state too
* when it's implemented.
*/
tor_assert(gs != NULL);
SMARTLIST_FOREACH_BEGIN(gs->chosen_entry_guards, entry_guard_t *, e)
{
const char *msg = NULL;
if (entry_is_live(e, ENTRY_NEED_CAPACITY, &msg))
smartlist_add_asprintf(elements, "%s [%s] (up %s)",
e->nickname,
hex_str(e->identity, DIGEST_LEN),
e->made_contact ? "made-contact" : "never-contacted");
else
smartlist_add_asprintf(elements, "%s [%s] (%s, %s)",
e->nickname,
hex_str(e->identity, DIGEST_LEN),
msg,
e->made_contact ? "made-contact" : "never-contacted");
}
SMARTLIST_FOREACH_END(e);
s = smartlist_join_strings(elements, ",", 0, NULL);
SMARTLIST_FOREACH(elements, char*, cp, tor_free(cp));
smartlist_free(elements);
log_fn(severity,LD_CIRC,"%s",s);
tor_free(s);
}
/** Called when one or more guards that we would previously have used for some
* purpose are no longer in use because a higher-priority guard has become
* usable again. */
static void
control_event_guard_deferred(void)
{
/* XXXX We don't actually have a good way to figure out _how many_ entries
* are live for some purpose. We need an entry_is_even_slightly_live()
* function for this to work right. NumEntryGuards isn't reliable: if we
* need guards with weird properties, we can have more than that number
* live.
**/
#if 0
int n = 0;
const char *msg;
const or_options_t *options = get_options();
if (!entry_guards)
return;
SMARTLIST_FOREACH(entry_guards, entry_guard_t *, entry,
{
if (entry_is_live(entry, 0, 1, 0, &msg)) {
if (n++ == options->NumEntryGuards) {
control_event_guard(entry->nickname, entry->identity, "DEFERRED");
return;
}
}
});
#endif
}
/** Add a new (preferably stable and fast) router to our chosen_entry_guards
* list for the supplied guard selection. Return a pointer to the router if
* we succeed, or NULL if we can't find any more suitable entries.
*
* If chosen is defined, use that one, and if it's not
* already in our entry_guards list, put it at the *beginning*.
* Else, put the one we pick at the end of the list. */
STATIC const node_t *
add_an_entry_guard(guard_selection_t *gs,
const node_t *chosen, int reset_status, int prepend,
int for_discovery, int for_directory)
{
const node_t *node;
entry_guard_t *entry;
tor_assert(gs != NULL);
tor_assert(gs->chosen_entry_guards != NULL);
if (chosen) {
node = chosen;
entry = entry_guard_get_by_id_digest_for_guard_selection(gs,
node->identity);
if (entry) {
if (reset_status) {
entry->bad_since = 0;
entry->can_retry = 1;
}
entry->is_dir_cache = node_is_dir(node);
if (get_options()->UseBridges && node_is_a_configured_bridge(node))
entry->is_dir_cache = 1;
return NULL;
}
} else if (!for_directory) {
node = choose_good_entry_server(CIRCUIT_PURPOSE_C_GENERAL, NULL, NULL);
if (!node)
return NULL;
} else {
const routerstatus_t *rs;
rs = router_pick_directory_server(MICRODESC_DIRINFO|V3_DIRINFO,
PDS_FOR_GUARD);
if (!rs)
return NULL;
node = node_get_by_id(rs->identity_digest);
if (!node)
return NULL;
}
if (entry_guard_get_by_id_digest_for_guard_selection(gs, node->identity)
!= NULL) {
log_info(LD_CIRC, "I was about to add a duplicate entry guard.");
/* This can happen if we choose a guard, then the node goes away, then
* comes back. */
return NULL;
}
entry = tor_malloc_zero(sizeof(entry_guard_t));
entry->is_persistent = 1;
log_info(LD_CIRC, "Chose %s as new entry guard.",
node_describe(node));
strlcpy(entry->nickname, node_get_nickname(node), sizeof(entry->nickname));
memcpy(entry->identity, node->identity, DIGEST_LEN);
entry->is_dir_cache = node_is_dir(node);
if (get_options()->UseBridges && node_is_a_configured_bridge(node))
entry->is_dir_cache = 1;
/* Choose expiry time smudged over the past month. The goal here
* is to a) spread out when Tor clients rotate their guards, so they
* don't all select them on the same day, and b) avoid leaving a
* precise timestamp in the state file about when we first picked
* this guard. For details, see the Jan 2010 or-dev thread. */
time_t now = time(NULL);
entry->chosen_on_date = crypto_rand_time_range(now - 3600*24*30, now);
entry->chosen_by_version = tor_strdup(VERSION);
/* Are we picking this guard because all of our current guards are
* down so we need another one (for_discovery is 1), or because we
* decided we need more variety in our guard list (for_discovery is 0)?
*
* Currently we hack this behavior into place by setting "made_contact"
* for guards of the latter variety, so we'll be willing to use any of
* them right off the bat.
*/
if (!for_discovery)
entry->made_contact = 1;
if (prepend)
smartlist_insert(gs->chosen_entry_guards, 0, entry);
else
smartlist_add(gs->chosen_entry_guards, entry);
entry->in_selection = gs;
control_event_guard(entry->nickname, entry->identity, "NEW");
control_event_guard_deferred();
log_entry_guards_for_guard_selection(gs, LOG_INFO);
return node;
}
/** Entry point for bridges.c to add a bridge as guard.
*
* XXXX prop271 refactor, bridge.*/
void
add_bridge_as_entry_guard(guard_selection_t *gs,
const node_t *chosen)
{
add_an_entry_guard(gs, chosen, 1, 1, 0, 0);
}
/**
* Return the minimum lifetime of working entry guard, in seconds,
* as given in the consensus networkstatus. (Plus CHOSEN_ON_DATE_SLOP,
* so that we can do the chosen_on_date randomization while achieving the
* desired minimum lifetime.)
*/
static int32_t
guards_get_lifetime(void)
{
const or_options_t *options = get_options();
#define DFLT_GUARD_LIFETIME (86400 * 60) /* Two months. */
#define MIN_GUARD_LIFETIME (86400 * 30) /* One months. */
#define MAX_GUARD_LIFETIME (86400 * 1826) /* Five years. */
if (options->GuardLifetime >= 1) {
return CLAMP(MIN_GUARD_LIFETIME,
options->GuardLifetime,
MAX_GUARD_LIFETIME) + CHOSEN_ON_DATE_SLOP;
}
return networkstatus_get_param(NULL, "GuardLifetime",
DFLT_GUARD_LIFETIME,
MIN_GUARD_LIFETIME,
MAX_GUARD_LIFETIME) + CHOSEN_ON_DATE_SLOP;
}
/** If the use of entry guards is configured, choose more entry guards
* until we have enough in the list. */
static void
pick_entry_guards(guard_selection_t *gs,
const or_options_t *options,
int for_directory)
{
int changed = 0;
const int num_needed = decide_num_guards(options, for_directory);
tor_assert(gs != NULL);
tor_assert(gs->chosen_entry_guards != NULL);
while (num_live_entry_guards_for_guard_selection(gs, for_directory)
< num_needed) {
if (!add_an_entry_guard(gs, NULL, 0, 0, 0, for_directory))
break;
changed = 1;
}
if (changed)
entry_guards_changed_for_guard_selection(gs);
}
/** Release all storage held by e. */
STATIC void
entry_guard_free(entry_guard_t *e)
{
if (!e)
return;
entry_guard_handles_clear(e);
tor_free(e->chosen_by_version);
tor_free(e->sampled_by_version);
tor_free(e->extra_state_fields);
tor_free(e->selection_name);
tor_free(e->bridge_addr);
tor_free(e);
}
/** Remove from a guard selection context any entry guard which was selected
* by an unknown version of Tor, or which was selected by a version of Tor
* that's known to select entry guards badly, or which was selected more 2
* months ago. */
/* XXXX The "obsolete guards" and "chosen long ago guards" things should
* probably be different functions. */
static int
remove_obsolete_entry_guards(guard_selection_t *gs, time_t now)
{
int changed = 0, i;
int32_t guard_lifetime = guards_get_lifetime();
tor_assert(gs != NULL);
if (!(gs->chosen_entry_guards)) goto done;
for (i = 0; i < smartlist_len(gs->chosen_entry_guards); ++i) {
entry_guard_t *entry = smartlist_get(gs->chosen_entry_guards, i);
const char *ver = entry->chosen_by_version;
const char *msg = NULL;
tor_version_t v;
int version_is_bad = 0, date_is_bad = 0;
if (!ver) {
msg = "does not say what version of Tor it was selected by";
version_is_bad = 1;
} else if (tor_version_parse(ver, &v)) {
msg = "does not seem to be from any recognized version of Tor";
version_is_bad = 1;
}
if (!version_is_bad && entry->chosen_on_date + guard_lifetime < now) {
/* It's been too long since the date listed in our state file. */
msg = "was selected several months ago";
date_is_bad = 1;
}
if (version_is_bad || date_is_bad) { /* we need to drop it */
char dbuf[HEX_DIGEST_LEN+1];
tor_assert(msg);
base16_encode(dbuf, sizeof(dbuf), entry->identity, DIGEST_LEN);
log_fn(version_is_bad ? LOG_NOTICE : LOG_INFO, LD_CIRC,
"Entry guard '%s' (%s) %s. (Version=%s.) Replacing it.",
entry->nickname, dbuf, msg, ver?escaped(ver):"none");
control_event_guard(entry->nickname, entry->identity, "DROPPED");
entry_guard_free(entry);
smartlist_del_keeporder(gs->chosen_entry_guards, i--);
log_entry_guards_for_guard_selection(gs, LOG_INFO);
changed = 1;
}
}
done:
return changed ? 1 : 0;
}
/** Remove all entry guards from this guard selection context that have
* been down or unlisted for so long that we don't think they'll come up
* again. Return 1 if we removed any, or 0 if we did nothing. */
static int
remove_dead_entry_guards(guard_selection_t *gs, time_t now)
{
char dbuf[HEX_DIGEST_LEN+1];
char tbuf[ISO_TIME_LEN+1];
int i;
int changed = 0;
tor_assert(gs != NULL);
if (!(gs->chosen_entry_guards)) goto done;
for (i = 0; i < smartlist_len(gs->chosen_entry_guards); ) {
entry_guard_t *entry = smartlist_get(gs->chosen_entry_guards, i);
if (entry->bad_since &&
! entry->pb.path_bias_disabled &&
entry->bad_since + ENTRY_GUARD_REMOVE_AFTER < now) {
base16_encode(dbuf, sizeof(dbuf), entry->identity, DIGEST_LEN);
format_local_iso_time(tbuf, entry->bad_since);
log_info(LD_CIRC, "Entry guard '%s' (%s) has been down or unlisted "
"since %s local time; removing.",
entry->nickname, dbuf, tbuf);
control_event_guard(entry->nickname, entry->identity, "DROPPED");
entry_guard_free(entry);
smartlist_del_keeporder(gs->chosen_entry_guards, i);
log_entry_guards_for_guard_selection(gs, LOG_INFO);
changed = 1;
} else
++i;
}
done:
return changed ? 1 : 0;
}
/** Remove all currently listed entry guards for a given guard selection
* context */
void
remove_all_entry_guards_for_guard_selection(guard_selection_t *gs)
{
char dbuf[HEX_DIGEST_LEN+1];
tor_assert(gs != NULL);
if (gs->chosen_entry_guards) {
while (smartlist_len(gs->chosen_entry_guards)) {
entry_guard_t *entry = smartlist_get(gs->chosen_entry_guards, 0);
base16_encode(dbuf, sizeof(dbuf), entry->identity, DIGEST_LEN);
log_info(LD_CIRC, "Entry guard '%s' (%s) has been dropped.",
entry->nickname, dbuf);
control_event_guard(entry->nickname, entry->identity, "DROPPED");
entry_guard_free(entry);
smartlist_del(gs->chosen_entry_guards, 0);
}
}
log_entry_guards_for_guard_selection(gs, LOG_INFO);
entry_guards_changed_for_guard_selection(gs);
}
/** Remove all currently listed entry guards. So new ones will be chosen. */
void
remove_all_entry_guards(void)
{
// XXXX prop271 this function shouldn't exist, in the new order.
remove_all_entry_guards_for_guard_selection(get_guard_selection_info());
}
/** A new directory or router-status has arrived; update the down/listed
* status of the entry guards.
*
* An entry is 'down' if the directory lists it as nonrunning.
* An entry is 'unlisted' if the directory doesn't include it.
*
* Don't call this on startup; only on a fresh download. Otherwise we'll
* think that things are unlisted.
*/
void
entry_guards_compute_status_for_guard_selection(guard_selection_t *gs,
const or_options_t *options,
time_t now)
{
int changed = 0;
digestmap_t *reasons;
if ((!gs) || !(gs->chosen_entry_guards))
return;
if (!get_options()->UseDeprecatedGuardAlgorithm)
return;
if (options->EntryNodes) /* reshuffle the entry guard list if needed */
entry_nodes_should_be_added();
reasons = digestmap_new();
SMARTLIST_FOREACH_BEGIN(gs->chosen_entry_guards, entry_guard_t *, entry)
{
const node_t *r = node_get_by_id(entry->identity);
const char *reason = NULL;
if (entry_guard_set_status(entry, r, now, options, &reason))
changed = 1;
if (entry->bad_since)
tor_assert(reason);
if (reason)
digestmap_set(reasons, entry->identity, (char*)reason);
}
SMARTLIST_FOREACH_END(entry);
if (remove_dead_entry_guards(gs, now))
changed = 1;
if (remove_obsolete_entry_guards(gs, now))
changed = 1;
if (changed) {
SMARTLIST_FOREACH_BEGIN(gs->chosen_entry_guards, entry_guard_t *,
entry) {
const char *reason = digestmap_get(reasons, entry->identity);
const char *live_msg = "";
const node_t *r = entry_is_live(entry, ENTRY_NEED_CAPACITY, &live_msg);
log_info(LD_CIRC, "Summary: Entry %s [%s] is %s, %s%s%s, and %s%s.",
entry->nickname,
hex_str(entry->identity, DIGEST_LEN),
entry->unreachable_since ? "unreachable" : "reachable",
entry->bad_since ? "unusable" : "usable",
reason ? ", ": "",
reason ? reason : "",
r ? "live" : "not live / ",
r ? "" : live_msg);
} SMARTLIST_FOREACH_END(entry);
log_info(LD_CIRC, " (%d/%d entry guards are usable/new)",
num_live_entry_guards_for_guard_selection(gs, 0),
smartlist_len(gs->chosen_entry_guards));
log_entry_guards_for_guard_selection(gs, LOG_INFO);
entry_guards_changed_for_guard_selection(gs);
}
digestmap_free(reasons, NULL);
}
/** A new directory or router-status has arrived; update the down/listed
* status of the entry guards.
*
* An entry is 'down' if the directory lists it as nonrunning.
* An entry is 'unlisted' if the directory doesn't include it.
*
* Don't call this on startup; only on a fresh download. Otherwise we'll
* think that things are unlisted.
*/
void
entry_guards_compute_status(const or_options_t *options, time_t now)
{
entry_guards_compute_status_for_guard_selection(get_guard_selection_info(),
options, now);
}
/** Called when a connection to an OR with the identity digest digest
* is established (succeeded==1) or has failed (succeeded==0).
* If the OR is an entry, change that entry's up/down status.
* Return 0 normally, or -1 if we want to tear down the new connection.
*
* If mark_relay_status, also call router_set_status() on this
* relay.
*/
/* XXX We could change succeeded and mark_relay_status into 'int flags'.
* Too many boolean arguments is a recipe for confusion.
*/
int
entry_guard_register_connect_status_for_guard_selection(
guard_selection_t *gs, const char *digest, int succeeded,
int mark_relay_status, time_t now)
{
int changed = 0;
int refuse_conn = 0;
int first_contact = 0;
entry_guard_t *entry = NULL;
int idx = -1;
char buf[HEX_DIGEST_LEN+1];
if (!(gs) || !(gs->chosen_entry_guards)) {
return 0;
}
if (! get_options()->UseDeprecatedGuardAlgorithm) {
return 0;
}
SMARTLIST_FOREACH_BEGIN(gs->chosen_entry_guards, entry_guard_t *, e) {
tor_assert(e);
if (tor_memeq(e->identity, digest, DIGEST_LEN)) {
entry = e;
idx = e_sl_idx;
break;
}
} SMARTLIST_FOREACH_END(e);
if (!entry)
return 0;
base16_encode(buf, sizeof(buf), entry->identity, DIGEST_LEN);
if (succeeded) {
if (entry->unreachable_since) {
log_info(LD_CIRC, "Entry guard '%s' (%s) is now reachable again. Good.",
entry->nickname, buf);
entry->can_retry = 0;
entry->unreachable_since = 0;
entry->last_attempted = now;
control_event_guard(entry->nickname, entry->identity, "UP");
changed = 1;
}
if (!entry->made_contact) {
entry->made_contact = 1;
first_contact = changed = 1;
}
} else { /* ! succeeded */
if (!entry->made_contact) {
/* We've never connected to this one. */
log_info(LD_CIRC,
"Connection to never-contacted entry guard '%s' (%s) failed. "
"Removing from the list. %d/%d entry guards usable/new.",
entry->nickname, buf,
num_live_entry_guards_for_guard_selection(gs, 0) - 1,
smartlist_len(gs->chosen_entry_guards)-1);
control_event_guard(entry->nickname, entry->identity, "DROPPED");
entry_guard_free(entry);
smartlist_del_keeporder(gs->chosen_entry_guards, idx);
log_entry_guards_for_guard_selection(gs, LOG_INFO);
changed = 1;
} else if (!entry->unreachable_since) {
log_info(LD_CIRC, "Unable to connect to entry guard '%s' (%s). "
"Marking as unreachable.", entry->nickname, buf);
entry->unreachable_since = entry->last_attempted = now;
control_event_guard(entry->nickname, entry->identity, "DOWN");
changed = 1;
entry->can_retry = 0; /* We gave it an early chance; no good. */
} else {
char tbuf[ISO_TIME_LEN+1];
format_iso_time(tbuf, entry->unreachable_since);
log_debug(LD_CIRC, "Failed to connect to unreachable entry guard "
"'%s' (%s). It has been unreachable since %s.",
entry->nickname, buf, tbuf);
entry->last_attempted = now;
entry->can_retry = 0; /* We gave it an early chance; no good. */
}
}
/* if the caller asked us to, also update the is_running flags for this
* relay */
if (mark_relay_status)
router_set_status(digest, succeeded);
if (first_contact) {
/* We've just added a new long-term entry guard. Perhaps the network just
* came back? We should give our earlier entries another try too,
* and close this connection so we don't use it before we've given
* the others a shot. */
SMARTLIST_FOREACH_BEGIN(gs->chosen_entry_guards, entry_guard_t *, e) {
if (e == entry)
break;
if (e->made_contact) {
const char *msg;
const node_t *r = entry_is_live(e,
ENTRY_NEED_CAPACITY | ENTRY_ASSUME_REACHABLE,
&msg);
if (r && e->unreachable_since) {
refuse_conn = 1;
e->can_retry = 1;
}
}
} SMARTLIST_FOREACH_END(e);
if (refuse_conn) {
log_info(LD_CIRC,
"Connected to new entry guard '%s' (%s). Marking earlier "
"entry guards up. %d/%d entry guards usable/new.",
entry->nickname, buf,
num_live_entry_guards_for_guard_selection(gs, 0),
smartlist_len(gs->chosen_entry_guards));
log_entry_guards_for_guard_selection(gs, LOG_INFO);
changed = 1;
}
}
if (changed)
entry_guards_changed_for_guard_selection(gs);
return refuse_conn ? -1 : 0;
}
/** Called when a connection to an OR with the identity digest digest
* is established (succeeded==1) or has failed (succeeded==0).
* If the OR is an entry, change that entry's up/down status in the default
* guard selection context.
* Return 0 normally, or -1 if we want to tear down the new connection.
*
* If mark_relay_status, also call router_set_status() on this
* relay.
*/
int
entry_guard_register_connect_status(const char *digest, int succeeded,
int mark_relay_status, time_t now)
{
return entry_guard_register_connect_status_for_guard_selection(
get_guard_selection_info(), digest, succeeded, mark_relay_status, now);
}
/** Called when the value of EntryNodes changes in our configuration. */
void
entry_nodes_should_be_added_for_guard_selection(guard_selection_t *gs)
{
tor_assert(gs != NULL);
log_info(LD_CIRC, "EntryNodes config option set. Putting configured "
"relays at the front of the entry guard list.");
gs->should_add_entry_nodes = 1;
}
/** Called when the value of EntryNodes changes in our configuration. */
void
entry_nodes_should_be_added(void)
{
entry_nodes_should_be_added_for_guard_selection(
get_guard_selection_info());
}
/** Adjust the entry guards list so that it only contains entries from
* EntryNodes, adding new entries from EntryNodes to the list as needed. */
STATIC void
entry_guards_set_from_config(guard_selection_t *gs,
const or_options_t *options)
{
smartlist_t *entry_nodes, *worse_entry_nodes, *entry_fps;
smartlist_t *old_entry_guards_on_list, *old_entry_guards_not_on_list;
const int numentryguards = decide_num_guards(options, 0);
tor_assert(gs != NULL);
tor_assert(gs->chosen_entry_guards != NULL);
gs->should_add_entry_nodes = 0;
if (!options->EntryNodes) {
/* It's possible that a controller set EntryNodes, thus making
* should_add_entry_nodes set, then cleared it again, all before the
* call to choose_random_entry() that triggered us. If so, just return.
*/
return;
}
{
char *string = routerset_to_string(options->EntryNodes);
log_info(LD_CIRC,"Adding configured EntryNodes '%s'.", string);
tor_free(string);
}
entry_nodes = smartlist_new();
worse_entry_nodes = smartlist_new();
entry_fps = smartlist_new();
old_entry_guards_on_list = smartlist_new();
old_entry_guards_not_on_list = smartlist_new();
/* Split entry guards into those on the list and those not. */
routerset_get_all_nodes(entry_nodes, options->EntryNodes,
options->ExcludeNodes, 0);
SMARTLIST_FOREACH(entry_nodes, const node_t *,node,
smartlist_add(entry_fps, (void*)node->identity));
SMARTLIST_FOREACH(gs->chosen_entry_guards, entry_guard_t *, e, {
if (smartlist_contains_digest(entry_fps, e->identity))
smartlist_add(old_entry_guards_on_list, e);
else
smartlist_add(old_entry_guards_not_on_list, e);
});
/* Remove all currently configured guard nodes, excluded nodes, unreachable
* nodes, or non-Guard nodes from entry_nodes. */
SMARTLIST_FOREACH_BEGIN(entry_nodes, const node_t *, node) {
if (entry_guard_get_by_id_digest_for_guard_selection(gs,
node->identity)) {
SMARTLIST_DEL_CURRENT(entry_nodes, node);
continue;
} else if (routerset_contains_node(options->ExcludeNodes, node)) {
SMARTLIST_DEL_CURRENT(entry_nodes, node);
continue;
} else if (!fascist_firewall_allows_node(node, FIREWALL_OR_CONNECTION,
0)) {
SMARTLIST_DEL_CURRENT(entry_nodes, node);
continue;
} else if (! node->is_possible_guard) {
smartlist_add(worse_entry_nodes, (node_t*)node);
SMARTLIST_DEL_CURRENT(entry_nodes, node);
}
} SMARTLIST_FOREACH_END(node);
/* Now build the new entry_guards list. */
smartlist_clear(gs->chosen_entry_guards);
/* First, the previously configured guards that are in EntryNodes. */
smartlist_add_all(gs->chosen_entry_guards, old_entry_guards_on_list);
/* Next, scramble the rest of EntryNodes, putting the guards first. */
smartlist_shuffle(entry_nodes);
smartlist_shuffle(worse_entry_nodes);
smartlist_add_all(entry_nodes, worse_entry_nodes);
/* Next, the rest of EntryNodes */
SMARTLIST_FOREACH_BEGIN(entry_nodes, const node_t *, node) {
add_an_entry_guard(gs, node, 0, 0, 1, 0);
if (smartlist_len(gs->chosen_entry_guards) > numentryguards * 10)
break;
} SMARTLIST_FOREACH_END(node);
log_notice(LD_GENERAL, "%d entries in guards",
smartlist_len(gs->chosen_entry_guards));
/* Finally, free the remaining previously configured guards that are not in
* EntryNodes. */
SMARTLIST_FOREACH(old_entry_guards_not_on_list, entry_guard_t *, e,
entry_guard_free(e));
smartlist_free(entry_nodes);
smartlist_free(worse_entry_nodes);
smartlist_free(entry_fps);
smartlist_free(old_entry_guards_on_list);
smartlist_free(old_entry_guards_not_on_list);
entry_guards_changed_for_guard_selection(gs);
}
/** Return 0 if we're fine adding arbitrary routers out of the
* directory to our entry guard list, or return 1 if we have a
* list already and we must stick to it.
*/
int
entry_list_is_constrained(const or_options_t *options)
{
if (options->EntryNodes)
return 1;
if (options->UseBridges)
return 1;
return 0;
}
/** Pick a live (up and listed) entry guard from entry_guards. If
* state is non-NULL, this is for a specific circuit --
* make sure not to pick this circuit's exit or any node in the
* exit's family. If state is NULL, we're looking for a random
* guard (likely a bridge). If dirinfo is not NO_DIRINFO (zero),
* then only select from nodes that know how to answer directory questions
* of that type. */
const node_t *
choose_random_entry(cpath_build_state_t *state)
{
tor_assert(get_options()->UseDeprecatedGuardAlgorithm);
return choose_random_entry_impl(get_guard_selection_info(),
state, 0, NO_DIRINFO, NULL);
}
/** Pick a live (up and listed) directory guard from entry_guards for
* downloading information of type type. */
const node_t *
choose_random_dirguard(dirinfo_type_t type)
{
tor_assert(get_options()->UseDeprecatedGuardAlgorithm);
return choose_random_entry_impl(get_guard_selection_info(),
NULL, 1, type, NULL);
}
/** Return the number of bridges that have descriptors that are marked with
* purpose 'bridge' and are running.
*/
int
num_bridges_usable(void)
{
int n_options = 0;
if (get_options()->UseDeprecatedGuardAlgorithm) {
tor_assert(get_options()->UseBridges);
(void) choose_random_entry_impl(get_guard_selection_info(),
NULL, 0, 0, &n_options);
} else {
/* XXXX prop271 Is this quite right? */
tor_assert(get_options()->UseBridges);
guard_selection_t *gs = get_guard_selection_info();
tor_assert(gs->type == GS_TYPE_BRIDGE);
SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
if (guard->is_reachable == GUARD_REACHABLE_NO)
continue;
if (tor_digest_is_zero(guard->identity))
continue;
const node_t *node = node_get_by_id(guard->identity);
if (node && node->ri)
++n_options;
} SMARTLIST_FOREACH_END(guard);
}
return n_options;
}
/** Filter all_entry_guards for usable entry guards and put them
* in live_entry_guards. We filter based on whether the node is
* currently alive, and on whether it satisfies the restrictions
* imposed by the other arguments of this function.
*
* We don't place more guards than NumEntryGuards in live_entry_guards.
*
* If chosen_exit is set, it contains the exit node of this
* circuit. Make sure to not use it or its family as an entry guard.
*
* If need_uptime is set, we are looking for a stable entry guard.
* if need_capacity is set, we are looking for a fast entry guard.
*
* The rest of the arguments are the same as in choose_random_entry_impl().
*
* Return 1 if we should choose a guard right away. Return 0 if we
* should try to add more nodes to our list before deciding on a
* guard.
*/
STATIC int
populate_live_entry_guards(smartlist_t *live_entry_guards,
const smartlist_t *all_entry_guards,
const node_t *chosen_exit,
dirinfo_type_t dirinfo_type,
int for_directory,
int need_uptime, int need_capacity)
{
const or_options_t *options = get_options();
const node_t *node = NULL;
const int num_needed = decide_num_guards(options, for_directory);
smartlist_t *exit_family = smartlist_new();
int retval = 0;
entry_is_live_flags_t entry_flags = 0;
(void) dirinfo_type;
{ /* Set the flags we want our entry node to have */
if (need_uptime) {
entry_flags |= ENTRY_NEED_UPTIME;
}
if (need_capacity) {
entry_flags |= ENTRY_NEED_CAPACITY;
}
if (!for_directory) {
entry_flags |= ENTRY_NEED_DESCRIPTOR;
}
}
tor_assert(all_entry_guards);
if (chosen_exit) {
nodelist_add_node_and_family(exit_family, chosen_exit);
}
SMARTLIST_FOREACH_BEGIN(all_entry_guards, const entry_guard_t *, entry) {
const char *msg;
node = entry_is_live(entry, entry_flags, &msg);
if (!node)
continue; /* down, no point */
if (for_directory) {
if (!entry->is_dir_cache)
continue; /* We need a directory and didn't get one. */
}
if (node == chosen_exit)
continue; /* don't pick the same node for entry and exit */
if (smartlist_contains(exit_family, node))
continue; /* avoid relays that are family members of our exit */
smartlist_add(live_entry_guards, (void*)node);
if (!entry->made_contact) {
/* Always start with the first not-yet-contacted entry
* guard. Otherwise we might add several new ones, pick
* the second new one, and now we've expanded our entry
* guard list without needing to. */
retval = 1;
goto done;
}
if (smartlist_len(live_entry_guards) >= num_needed) {
retval = 1;
goto done; /* We picked enough entry guards. Done! */
}
} SMARTLIST_FOREACH_END(entry);
done:
smartlist_free(exit_family);
return retval;
}
/** Pick a node to be used as the entry guard of a circuit, relative to
* a supplied guard selection context.
*
* If state is set, it contains the information we know about
* the upcoming circuit.
*
* If for_directory is set, we are looking for a directory guard.
*
* dirinfo_type contains the kind of directory information we
* are looking for in our node, or NO_DIRINFO (zero) if we are not
* looking for any particular directory information (when set to
* NO_DIRINFO, the dirinfo_type filter is ignored).
*
* If n_options_out is set, we set it to the number of
* candidate guard nodes we had before picking a specific guard node.
*
* On success, return the node that should be used as the entry guard
* of the circuit. Return NULL if no such node could be found.
*
* Helper for choose_random{entry,dirguard}.
*/
static const node_t *
choose_random_entry_impl(guard_selection_t *gs,
cpath_build_state_t *state, int for_directory,
dirinfo_type_t dirinfo_type, int *n_options_out)
{
const or_options_t *options = get_options();
smartlist_t *live_entry_guards = smartlist_new();
const node_t *chosen_exit =
state?build_state_get_exit_node(state) : NULL;
const node_t *node = NULL;
int need_uptime = state ? state->need_uptime : 0;
int need_capacity = state ? state->need_capacity : 0;
int preferred_min = 0;
const int num_needed = decide_num_guards(options, for_directory);
int retval = 0;
tor_assert(gs != NULL);
tor_assert(gs->chosen_entry_guards != NULL);
if (n_options_out)
*n_options_out = 0;
if (gs->should_add_entry_nodes)
entry_guards_set_from_config(gs, options);
if (!entry_list_is_constrained(options) &&
smartlist_len(gs->chosen_entry_guards) < num_needed)
pick_entry_guards(gs, options, for_directory);
retry:
smartlist_clear(live_entry_guards);
/* Populate the list of live entry guards so that we pick one of
them. */
retval = populate_live_entry_guards(live_entry_guards,
gs->chosen_entry_guards,
chosen_exit,
dirinfo_type,
for_directory,
need_uptime, need_capacity);
if (retval == 1) { /* We should choose a guard right now. */
goto choose_and_finish;
}
if (entry_list_is_constrained(options)) {
/* If we prefer the entry nodes we've got, and we have at least
* one choice, that's great. Use it. */
preferred_min = 1;
} else {
/* Try to have at least 2 choices available. This way we don't
* get stuck with a single live-but-crummy entry and just keep
* using it.
* (We might get 2 live-but-crummy entry guards, but so be it.) */
preferred_min = 2;
}
if (smartlist_len(live_entry_guards) < preferred_min) {
if (!entry_list_is_constrained(options)) {
/* still no? try adding a new entry then */
/* XXX if guard doesn't imply fast and stable, then we need
* to tell add_an_entry_guard below what we want, or it might
* be a long time til we get it. -RD */
node = add_an_entry_guard(gs, NULL, 0, 0, 1, for_directory);
if (node) {
entry_guards_changed_for_guard_selection(gs);
/* XXX we start over here in case the new node we added shares
* a family with our exit node. There's a chance that we'll just
* load up on entry guards here, if the network we're using is
* one big family. Perhaps we should teach add_an_entry_guard()
* to understand nodes-to-avoid-if-possible? -RD */
goto retry;
}
}
if (!node && need_uptime) {
need_uptime = 0; /* try without that requirement */
goto retry;
}
if (!node && need_capacity) {
/* still no? last attempt, try without requiring capacity */
need_capacity = 0;
goto retry;
}
/* live_entry_guards may be empty below. Oh well, we tried. */
}
choose_and_finish:
if (entry_list_is_constrained(options)) {
/* We need to weight by bandwidth, because our bridges or entryguards
* were not already selected proportional to their bandwidth. */
node = node_sl_choose_by_bandwidth(live_entry_guards, WEIGHT_FOR_GUARD);
} else {
/* We choose uniformly at random here, because choose_good_entry_server()
* already weights its choices by bandwidth, so we don't want to
* *double*-weight our guard selection. */
node = smartlist_choose(live_entry_guards);
}
if (n_options_out)
*n_options_out = smartlist_len(live_entry_guards);
smartlist_free(live_entry_guards);
return node;
}
static void
pathbias_check_use_success_count(entry_guard_t *node)
{
const or_options_t *options = get_options();
const double EPSILON = 1.0e-9;
/* Note: We rely on the < comparison here to allow us to set a 0
* rate and disable the feature entirely. If refactoring, don't
* change to <= */
if (node->pb.use_attempts > EPSILON &&
pathbias_get_use_success_count(node)/node->pb.use_attempts
< pathbias_get_extreme_use_rate(options) &&
pathbias_get_dropguards(options)) {
node->pb.path_bias_disabled = 1;
log_info(LD_GENERAL,
"Path use bias is too high (%f/%f); disabling node %s",
node->pb.circ_successes, node->pb.circ_attempts,
node->nickname);
}
}
static void
pathbias_check_close_success_count(entry_guard_t *node)
{
const or_options_t *options = get_options();
const double EPSILON = 1.0e-9;
/* Note: We rely on the < comparison here to allow us to set a 0
* rate and disable the feature entirely. If refactoring, don't
* change to <= */
if (node->pb.circ_attempts > EPSILON &&
pathbias_get_close_success_count(node)/node->pb.circ_attempts
< pathbias_get_extreme_rate(options) &&
pathbias_get_dropguards(options)) {
node->pb.path_bias_disabled = 1;
log_info(LD_GENERAL,
"Path bias is too high (%f/%f); disabling node %s",
node->pb.circ_successes, node->pb.circ_attempts,
node->nickname);
}
}
/** Parse state and learn about the entry guards it describes.
* If set is true, and there are no errors, replace the guard
* list in the provided guard selection context with what we find.
* On success, return 0. On failure, alloc into *msg a string
* describing the error, and return -1.
*/
int
entry_guards_parse_state_for_guard_selection(
guard_selection_t *gs,
or_state_t *state, int set, char **msg)
{
entry_guard_t *node = NULL;
smartlist_t *new_entry_guards = smartlist_new();
config_line_t *line;
time_t now = time(NULL);
const char *state_version = state->TorVersion;
digestmap_t *added_by = digestmap_new();
tor_assert(gs != NULL);
*msg = NULL;
for (line = state->EntryGuards; line; line = line->next) {
if (!strcasecmp(line->key, "EntryGuard")) {
smartlist_t *args = smartlist_new();
node = tor_malloc_zero(sizeof(entry_guard_t));
/* all entry guards on disk have been contacted */
node->made_contact = 1;
node->is_persistent = 1;
smartlist_add(new_entry_guards, node);
smartlist_split_string(args, line->value, " ",
SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
if (smartlist_len(args)<2) {
*msg = tor_strdup("Unable to parse entry nodes: "
"Too few arguments to EntryGuard");
} else if (!is_legal_nickname(smartlist_get(args,0))) {
*msg = tor_strdup("Unable to parse entry nodes: "
"Bad nickname for EntryGuard");
} else {
strlcpy(node->nickname, smartlist_get(args,0), MAX_NICKNAME_LEN+1);
if (base16_decode(node->identity, DIGEST_LEN, smartlist_get(args,1),
strlen(smartlist_get(args,1))) != DIGEST_LEN) {
*msg = tor_strdup("Unable to parse entry nodes: "
"Bad hex digest for EntryGuard");
}
}
if (smartlist_len(args) >= 3) {
const char *is_cache = smartlist_get(args, 2);
if (!strcasecmp(is_cache, "DirCache")) {
node->is_dir_cache = 1;
} else if (!strcasecmp(is_cache, "NoDirCache")) {
node->is_dir_cache = 0;
} else {
log_warn(LD_CONFIG, "Bogus third argument to EntryGuard line: %s",
escaped(is_cache));
}
}
SMARTLIST_FOREACH(args, char*, cp, tor_free(cp));
smartlist_free(args);
if (*msg)
break;
} else if (!strcasecmp(line->key, "EntryGuardDownSince") ||
!strcasecmp(line->key, "EntryGuardUnlistedSince")) {
time_t when;
time_t last_try = 0;
if (!node) {
*msg = tor_strdup("Unable to parse entry nodes: "
"EntryGuardDownSince/UnlistedSince without EntryGuard");
break;
}
if (parse_iso_time_(line->value, &when, 0, 0)<0) {
*msg = tor_strdup("Unable to parse entry nodes: "
"Bad time in EntryGuardDownSince/UnlistedSince");
break;
}
if (when > now) {
/* It's a bad idea to believe info in the future: you can wind
* up with timeouts that aren't allowed to happen for years. */
continue;
}
if (strlen(line->value) >= ISO_TIME_LEN+ISO_TIME_LEN+1) {
/* ignore failure */
(void) parse_iso_time(line->value+ISO_TIME_LEN+1, &last_try);
}
if (!strcasecmp(line->key, "EntryGuardDownSince")) {
node->unreachable_since = when;
node->last_attempted = last_try;
} else {
node->bad_since = when;
}
} else if (!strcasecmp(line->key, "EntryGuardAddedBy")) {
char d[DIGEST_LEN];
/* format is digest version date */
if (strlen(line->value) < HEX_DIGEST_LEN+1+1+1+ISO_TIME_LEN) {
log_warn(LD_BUG, "EntryGuardAddedBy line is not long enough.");
continue;
}
if (base16_decode(d, sizeof(d),
line->value, HEX_DIGEST_LEN) != sizeof(d) ||
line->value[HEX_DIGEST_LEN] != ' ') {
log_warn(LD_BUG, "EntryGuardAddedBy line %s does not begin with "
"hex digest", escaped(line->value));
continue;
}
digestmap_set(added_by, d, tor_strdup(line->value+HEX_DIGEST_LEN+1));
} else if (!strcasecmp(line->key, "EntryGuardPathUseBias")) {
double use_cnt, success_cnt;
if (!node) {
*msg = tor_strdup("Unable to parse entry nodes: "
"EntryGuardPathUseBias without EntryGuard");
break;
}
if (tor_sscanf(line->value, "%lf %lf",
&use_cnt, &success_cnt) != 2) {
log_info(LD_GENERAL, "Malformed path use bias line for node %s",
node->nickname);
continue;
}
if (use_cnt < success_cnt) {
int severity = LOG_INFO;
/* If this state file was written by a Tor that would have
* already fixed it, then the overcounting bug is still there.. */
if (tor_version_as_new_as(state_version, "0.2.4.13-alpha")) {
severity = LOG_NOTICE;
}
log_fn(severity, LD_BUG,
"State file contains unexpectedly high usage success "
"counts %lf/%lf for Guard %s ($%s)",
success_cnt, use_cnt,
node->nickname, hex_str(node->identity, DIGEST_LEN));
success_cnt = use_cnt;
}
node->pb.use_attempts = use_cnt;
node->pb.use_successes = success_cnt;
log_info(LD_GENERAL, "Read %f/%f path use bias for node %s",
node->pb.use_successes, node->pb.use_attempts, node->nickname);
pathbias_check_use_success_count(node);
} else if (!strcasecmp(line->key, "EntryGuardPathBias")) {
double hop_cnt, success_cnt, timeouts, collapsed, successful_closed,
unusable;
if (!node) {
*msg = tor_strdup("Unable to parse entry nodes: "
"EntryGuardPathBias without EntryGuard");
break;
}
/* First try 3 params, then 2. */
/* In the long run: circuit_success ~= successful_circuit_close +
* collapsed_circuits +
* unusable_circuits */
if (tor_sscanf(line->value, "%lf %lf %lf %lf %lf %lf",
&hop_cnt, &success_cnt, &successful_closed,
&collapsed, &unusable, &timeouts) != 6) {
int old_success, old_hops;
if (tor_sscanf(line->value, "%u %u", &old_success, &old_hops) != 2) {
continue;
}
log_info(LD_GENERAL, "Reading old-style EntryGuardPathBias %s",
escaped(line->value));
success_cnt = old_success;
successful_closed = old_success;
hop_cnt = old_hops;
timeouts = 0;
collapsed = 0;
unusable = 0;
}
if (hop_cnt < success_cnt) {
int severity = LOG_INFO;
/* If this state file was written by a Tor that would have
* already fixed it, then the overcounting bug is still there.. */
if (tor_version_as_new_as(state_version, "0.2.4.13-alpha")) {
severity = LOG_NOTICE;
}
log_fn(severity, LD_BUG,
"State file contains unexpectedly high success counts "
"%lf/%lf for Guard %s ($%s)",
success_cnt, hop_cnt,
node->nickname, hex_str(node->identity, DIGEST_LEN));
success_cnt = hop_cnt;
}
node->pb.circ_attempts = hop_cnt;
node->pb.circ_successes = success_cnt;
node->pb.successful_circuits_closed = successful_closed;
node->pb.timeouts = timeouts;
node->pb.collapsed_circuits = collapsed;
node->pb.unusable_circuits = unusable;
log_info(LD_GENERAL, "Read %f/%f path bias for node %s",
node->pb.circ_successes, node->pb.circ_attempts,
node->nickname);
pathbias_check_close_success_count(node);
} else {
log_warn(LD_BUG, "Unexpected key %s", line->key);
}
}
SMARTLIST_FOREACH_BEGIN(new_entry_guards, entry_guard_t *, e) {
char *sp;
char *val = digestmap_get(added_by, e->identity);
if (val && (sp = strchr(val, ' '))) {
time_t when;
*sp++ = '\0';
if (parse_iso_time(sp, &when)<0) {
log_warn(LD_BUG, "Can't read time %s in EntryGuardAddedBy", sp);
} else {
e->chosen_by_version = tor_strdup(val);
e->chosen_on_date = when;
}
} else {
if (state_version) {
e->chosen_on_date = crypto_rand_time_range(now - 3600*24*30, now);
e->chosen_by_version = tor_strdup(state_version);
}
}
if (e->pb.path_bias_disabled && !e->bad_since)
e->bad_since = time(NULL);
}
SMARTLIST_FOREACH_END(e);
if (*msg || !set) {
SMARTLIST_FOREACH(new_entry_guards, entry_guard_t *, e,
entry_guard_free(e));
smartlist_free(new_entry_guards);
} else { /* !err && set */
if (gs->chosen_entry_guards) {
SMARTLIST_FOREACH(gs->chosen_entry_guards, entry_guard_t *, e,
entry_guard_free(e));
smartlist_free(gs->chosen_entry_guards);
}
gs->chosen_entry_guards = new_entry_guards;
SMARTLIST_FOREACH(new_entry_guards, entry_guard_t *, e,
e->in_selection = gs);
/* XXX hand new_entry_guards to this func, and move it up a
* few lines, so we don't have to re-dirty it */
if (remove_obsolete_entry_guards(gs, now))
entry_guards_dirty = 1;
}
digestmap_free(added_by, tor_free_);
return *msg ? -1 : 0;
}
/** Parse state and learn about the entry guards it describes.
* If set is true, and there are no errors, replace the guard
* list in the default guard selection context with what we find.
* On success, return 0. On failure, alloc into *msg a string
* describing the error, and return -1.
*/
int
entry_guards_parse_state(or_state_t *state, int set, char **msg)
{
entry_guards_dirty = 0;
int r1 = entry_guards_load_guards_from_state(state, set);
int r2 = entry_guards_parse_state_for_guard_selection(
get_guard_selection_by_name("legacy", GS_TYPE_LEGACY, 1),
state, set, msg);
entry_guards_dirty = 0;
if (r1 < 0 || r2 < 0) {
if (msg && *msg == NULL) {
*msg = tor_strdup("parsing error"); //xxxx prop271 should we try harder?
}
return -1;
}
return 0;
}
/** How long will we let a change in our guard nodes stay un-saved
* when we are trying to avoid disk writes? */
#define SLOW_GUARD_STATE_FLUSH_TIME 600
/** How long will we let a change in our guard nodes stay un-saved
* when we are not trying to avoid disk writes? */
#define FAST_GUARD_STATE_FLUSH_TIME 30
/** Our list of entry guards has changed for a particular guard selection
* context, or some element of one of our entry guards has changed for one.
* Write the changes to disk within the next few minutes.
*/
void
entry_guards_changed_for_guard_selection(guard_selection_t *gs)
{
time_t when;
tor_assert(gs != NULL);
entry_guards_dirty = 1;
if (get_options()->AvoidDiskWrites)
when = time(NULL) + SLOW_GUARD_STATE_FLUSH_TIME;
else
when = time(NULL) + FAST_GUARD_STATE_FLUSH_TIME;
/* or_state_save() will call entry_guards_update_state() and
entry_guards_update_guards_in_state()
*/
or_state_mark_dirty(get_or_state(), when);
}
/** Our list of entry guards has changed for the default guard selection
* context, or some element of one of our entry guards has changed. Write
* the changes to disk within the next few minutes.
*/
void
entry_guards_changed(void)
{
entry_guards_changed_for_guard_selection(get_guard_selection_info());
}
/** If the entry guard info has not changed, do nothing and return.
* Otherwise, free the EntryGuards piece of state and create
* a new one out of the global entry_guards list, and then mark
* state dirty so it will get saved to disk.
*/
void
entry_guards_update_state(or_state_t *state)
{
config_line_t **next, *line;
entry_guards_dirty = 0;
// Handles all non-legacy guard info.
entry_guards_update_guards_in_state(state);
entry_guards_dirty = 0;
guard_selection_t *gs;
gs = get_guard_selection_by_name("legacy", GS_TYPE_LEGACY, 0);
if (!gs)
return; // nothign to save.
tor_assert(gs->chosen_entry_guards != NULL);
config_free_lines(state->EntryGuards);
next = &state->EntryGuards;
*next = NULL;
SMARTLIST_FOREACH_BEGIN(gs->chosen_entry_guards, entry_guard_t *, e) {
char dbuf[HEX_DIGEST_LEN+1];
if (!e->made_contact)
continue; /* don't write this one to disk */
*next = line = tor_malloc_zero(sizeof(config_line_t));
line->key = tor_strdup("EntryGuard");
base16_encode(dbuf, sizeof(dbuf), e->identity, DIGEST_LEN);
tor_asprintf(&line->value, "%s %s %sDirCache", e->nickname, dbuf,
e->is_dir_cache ? "" : "No");
next = &(line->next);
if (e->unreachable_since) {
*next = line = tor_malloc_zero(sizeof(config_line_t));
line->key = tor_strdup("EntryGuardDownSince");
line->value = tor_malloc(ISO_TIME_LEN+1+ISO_TIME_LEN+1);
format_iso_time(line->value, e->unreachable_since);
if (e->last_attempted) {
line->value[ISO_TIME_LEN] = ' ';
format_iso_time(line->value+ISO_TIME_LEN+1, e->last_attempted);
}
next = &(line->next);
}
if (e->bad_since) {
*next = line = tor_malloc_zero(sizeof(config_line_t));
line->key = tor_strdup("EntryGuardUnlistedSince");
line->value = tor_malloc(ISO_TIME_LEN+1);
format_iso_time(line->value, e->bad_since);
next = &(line->next);
}
if (e->chosen_on_date && e->chosen_by_version &&
!strchr(e->chosen_by_version, ' ')) {
char d[HEX_DIGEST_LEN+1];
char t[ISO_TIME_LEN+1];
*next = line = tor_malloc_zero(sizeof(config_line_t));
line->key = tor_strdup("EntryGuardAddedBy");
base16_encode(d, sizeof(d), e->identity, DIGEST_LEN);
format_iso_time(t, e->chosen_on_date);
tor_asprintf(&line->value, "%s %s %s",
d, e->chosen_by_version, t);
next = &(line->next);
}
if (e->pb.circ_attempts > 0) {
*next = line = tor_malloc_zero(sizeof(config_line_t));
line->key = tor_strdup("EntryGuardPathBias");
/* In the long run: circuit_success ~= successful_circuit_close +
* collapsed_circuits +
* unusable_circuits */
tor_asprintf(&line->value, "%f %f %f %f %f %f",
e->pb.circ_attempts, e->pb.circ_successes,
pathbias_get_close_success_count(e),
e->pb.collapsed_circuits,
e->pb.unusable_circuits, e->pb.timeouts);
next = &(line->next);
}
if (e->pb.use_attempts > 0) {
*next = line = tor_malloc_zero(sizeof(config_line_t));
line->key = tor_strdup("EntryGuardPathUseBias");
tor_asprintf(&line->value, "%f %f",
e->pb.use_attempts,
pathbias_get_use_success_count(e));
next = &(line->next);
}
} SMARTLIST_FOREACH_END(e);
if (!get_options()->AvoidDiskWrites)
or_state_mark_dirty(get_or_state(), 0);
entry_guards_dirty = 0;
}
/** If question is the string "entry-guards", then dump
* to *answer a newly allocated string describing all of
* the nodes in the global entry_guards list. See control-spec.txt
* for details.
* For backward compatibility, we also handle the string "helper-nodes".
*
* XXX this should be totally redesigned after prop 271 too, and that's
* going to take some control spec work.
* */
int
getinfo_helper_entry_guards(control_connection_t *conn,
const char *question, char **answer,
const char **errmsg)
{
guard_selection_t *gs = get_guard_selection_info();
tor_assert(gs != NULL);
tor_assert(gs->chosen_entry_guards != NULL);
(void) conn;
(void) errmsg;
if (!strcmp(question,"entry-guards") ||
!strcmp(question,"helper-nodes")) {
smartlist_t *sl = smartlist_new();
char tbuf[ISO_TIME_LEN+1];
char nbuf[MAX_VERBOSE_NICKNAME_LEN+1];
SMARTLIST_FOREACH_BEGIN(gs->chosen_entry_guards, entry_guard_t *, e) {
const char *status = NULL;
time_t when = 0;
const node_t *node;
if (!e->made_contact) {
status = "never-connected";
} else if (e->bad_since) {
when = e->bad_since;
status = "unusable";
} else if (e->unreachable_since) {
when = e->unreachable_since;
status = "down";
} else {
status = "up";
}
node = node_get_by_id(e->identity);
if (node) {
node_get_verbose_nickname(node, nbuf);
} else {
nbuf[0] = '$';
base16_encode(nbuf+1, sizeof(nbuf)-1, e->identity, DIGEST_LEN);
/* e->nickname field is not very reliable if we don't know about
* this router any longer; don't include it. */
}
if (when) {
format_iso_time(tbuf, when);
smartlist_add_asprintf(sl, "%s %s %s\n", nbuf, status, tbuf);
} else {
smartlist_add_asprintf(sl, "%s %s\n", nbuf, status);
}
} SMARTLIST_FOREACH_END(e);
*answer = smartlist_join_strings(sl, "", 0, NULL);
SMARTLIST_FOREACH(sl, char *, c, tor_free(c));
smartlist_free(sl);
}
return 0;
}
/* Given the original bandwidth of a guard and its guardfraction,
* calculate how much bandwidth the guard should have as a guard and
* as a non-guard.
*
* Quoting from proposal236:
*
* Let Wpf denote the weight from the 'bandwidth-weights' line a
* client would apply to N for position p if it had the guard
* flag, Wpn the weight if it did not have the guard flag, and B the
* measured bandwidth of N in the consensus. Then instead of choosing
* N for position p proportionally to Wpf*B or Wpn*B, clients should
* choose N proportionally to F*Wpf*B + (1-F)*Wpn*B.
*
* This function fills the guardfraction_bw structure. It sets
* guard_bw to F*B and non_guard_bw to (1-F)*B.
*/
void
guard_get_guardfraction_bandwidth(guardfraction_bandwidth_t *guardfraction_bw,
int orig_bandwidth,
uint32_t guardfraction_percentage)
{
double guardfraction_fraction;
/* Turn the percentage into a fraction. */
tor_assert(guardfraction_percentage <= 100);
guardfraction_fraction = guardfraction_percentage / 100.0;
long guard_bw = tor_lround(guardfraction_fraction * orig_bandwidth);
tor_assert(guard_bw <= INT_MAX);
guardfraction_bw->guard_bw = (int) guard_bw;
guardfraction_bw->non_guard_bw = orig_bandwidth - (int) guard_bw;
}
/** Returns true iff the node is used as a guard in the specified guard
* context */
int
is_node_used_as_guard_for_guard_selection(guard_selection_t *gs,
const node_t *node)
{
int res = 0;
/*
* We used to have a using_as_guard flag in node_t, but it had to go away
* to allow for multiple guard selection contexts. Instead, search the
* guard list for a matching digest.
*/
tor_assert(gs != NULL);
tor_assert(node != NULL);
SMARTLIST_FOREACH_BEGIN(gs->chosen_entry_guards, entry_guard_t *, e) {
if (tor_memeq(e->identity, node->identity, DIGEST_LEN)) {
res = 1;
break;
}
} SMARTLIST_FOREACH_END(e);
return res;
}
/** Returns true iff the node is used as a guard in the default guard
* context */
MOCK_IMPL(int,
is_node_used_as_guard, (const node_t *node))
{
return is_node_used_as_guard_for_guard_selection(
get_guard_selection_info(), node);
}
/** Return 1 if we have at least one descriptor for an entry guard
* (bridge or member of EntryNodes) and all descriptors we know are
* down. Else return 0. If act is 1, then mark the down guards
* up; else just observe and report. */
static int
entries_retry_helper(const or_options_t *options, int act)
{
const node_t *node;
int any_known = 0;
int any_running = 0;
int need_bridges = options->UseBridges != 0;
guard_selection_t *gs = get_guard_selection_info();
tor_assert(gs != NULL);
tor_assert(gs->chosen_entry_guards != NULL);
SMARTLIST_FOREACH_BEGIN(gs->chosen_entry_guards, entry_guard_t *, e) {
node = node_get_by_id(e->identity);
if (node && node_has_descriptor(node) &&
node_is_bridge(node) == need_bridges &&
(!need_bridges || (!e->bad_since &&
node_is_a_configured_bridge(node)))) {
any_known = 1;
if (node->is_running)
any_running = 1; /* some entry is both known and running */
else if (act) {
/* Mark all current connections to this OR as unhealthy, since
* otherwise there could be one that started 30 seconds
* ago, and in 30 seconds it will time out, causing us to mark
* the node down and undermine the retry attempt. We mark even
* the established conns, since if the network just came back
* we'll want to attach circuits to fresh conns. */
connection_or_set_bad_connections(node->identity, 1);
/* mark this entry node for retry */
router_set_status(node->identity, 1);
e->can_retry = 1;
e->bad_since = 0;
}
}
} SMARTLIST_FOREACH_END(e);
log_debug(LD_DIR, "%d: any_known %d, any_running %d",
act, any_known, any_running);
return any_known && !any_running;
}
/** Do we know any descriptors for our bridges / entrynodes, and are
* all the ones we have descriptors for down? */
int
entries_known_but_down(const or_options_t *options)
{
tor_assert(entry_list_is_constrained(options));
return entries_retry_helper(options, 0);
}
/** Mark all down known bridges / entrynodes up. */
void
entries_retry_all(const or_options_t *options)
{
tor_assert(entry_list_is_constrained(options));
entries_retry_helper(options, 1);
}
/** Helper: Update the status of all entry guards, in whatever algorithm
* is used. Return true if we should stop using all previously generated
* circuits. */
int
guards_update_all(void)
{
int mark_circuits = 0;
if (update_guard_selection_choice(get_options()))
mark_circuits = 1;
tor_assert(curr_guard_context);
if (curr_guard_context->type == GS_TYPE_LEGACY) {
entry_guards_compute_status(get_options(), approx_time());
} else {
if (entry_guards_update_all(curr_guard_context))
mark_circuits = 1;
}
return mark_circuits;
}
/** Helper: pick a guard for a circuit, with whatever algorithm is
used. */
const node_t *
guards_choose_guard(cpath_build_state_t *state,
circuit_guard_state_t **guard_state_out)
{
if (get_options()->UseDeprecatedGuardAlgorithm) {
return choose_random_entry(state);
} else {
const node_t *r = NULL;
const uint8_t *exit_id = NULL;
entry_guard_restriction_t *rst = NULL;
// XXXX prop271 spec deviation -- use of restriction here.
if (state && (exit_id = build_state_get_exit_rsa_id(state))) {
/* We're building to a targeted exit node, so that node can't be
* chosen as our guard for this circuit. */
rst = tor_malloc_zero(sizeof(entry_guard_restriction_t));
memcpy(rst->exclude_id, exit_id, DIGEST_LEN);
}
if (entry_guard_pick_for_circuit(get_guard_selection_info(),
rst,
&r,
guard_state_out) < 0) {
tor_assert(r == NULL);
}
return r;
}
}
/** Helper: pick a directory guard, with whatever algorithm is used. */
const node_t *
guards_choose_dirguard(dirinfo_type_t info,
circuit_guard_state_t **guard_state_out)
{
if (get_options()->UseDeprecatedGuardAlgorithm) {
return choose_random_dirguard(info);
} else {
/* XXXX prop271 We don't need to look at the dirinfo_type_t here,
* apparently. If you look at the old implementation, and you follow info
* downwards through choose_random_dirguard(), into
* choose_random_entry_impl(), into populate_live_entry_guards()... you
* find out that it isn't even used, and hasn't been since 0.2.7.1-alpha,
* when we realized that every Tor on the network would support
* microdescriptors. -NM */
const node_t *r = NULL;
if (entry_guard_pick_for_circuit(get_guard_selection_info(),
NULL,
&r,
guard_state_out) < 0) {
tor_assert(r == NULL);
}
return r;
}
}
/** Free one guard selection context */
STATIC void
guard_selection_free(guard_selection_t *gs)
{
if (!gs) return;
tor_free(gs->name);
if (gs->chosen_entry_guards) {
SMARTLIST_FOREACH(gs->chosen_entry_guards, entry_guard_t *, e,
entry_guard_free(e));
smartlist_free(gs->chosen_entry_guards);
gs->chosen_entry_guards = NULL;
}
if (gs->sampled_entry_guards) {
SMARTLIST_FOREACH(gs->sampled_entry_guards, entry_guard_t *, e,
entry_guard_free(e));
smartlist_free(gs->sampled_entry_guards);
gs->sampled_entry_guards = NULL;
}
smartlist_free(gs->confirmed_entry_guards);
smartlist_free(gs->primary_entry_guards);
tor_free(gs);
}
/** Release all storage held by the list of entry guards and related
* memory structs. */
void
entry_guards_free_all(void)
{
/* Null out the default */
curr_guard_context = NULL;
/* Free all the guard contexts */
if (guard_contexts != NULL) {
SMARTLIST_FOREACH_BEGIN(guard_contexts, guard_selection_t *, gs) {
guard_selection_free(gs);
} SMARTLIST_FOREACH_END(gs);
smartlist_free(guard_contexts);
guard_contexts = NULL;
}
circuit_build_times_free_timeouts(get_circuit_build_times_mutable());
}