/* 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).
**/
#define ENTRYNODES_PRIVATE
#include "or.h"
#include "bridges.h"
#include "circpathbias.h"
#include "circuitbuild.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"
/** All the context for guard selection on a particular client */
struct guard_selection_s {
/**
* A value of 1 means that guard_selection_t structures have changed
* and those changes need to be flushed to disk.
*
* XXX we don't know how to flush multiple guard contexts to disk yet;
* fix that as soon as any way to change the default exists, or at least
* make sure this gets set on change.
*/
int dirty;
/**
* A list of the sampled entry guards, as entry_guard_t structures.
* Not in any particular order. */
smartlist_t *sampled_entry_guards;
/**
* A list of our chosen entry guards, as entry_guard_t structures; this
* preserves the pre-Prop271 behavior.
*/
smartlist_t *chosen_entry_guards;
/**
* When we try to choose an entry guard, should we parse and add
* config's EntryNodes first? This was formerly a global.
*/
int should_add_entry_nodes;
int filtered_up_to_date;
};
static smartlist_t *guard_contexts = NULL;
static guard_selection_t *curr_guard_context = NULL;
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 guard_selection_t * guard_selection_new(void);
/* 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
/** Allocate a new guard_selection_t */
static guard_selection_t *
guard_selection_new(void)
{
guard_selection_t *gs;
gs = tor_malloc_zero(sizeof(*gs));
gs->chosen_entry_guards = smartlist_new();
gs->sampled_entry_guards = smartlist_new();
return gs;
}
/** Get current default guard_selection_t, creating it if necessary */
guard_selection_t *
get_guard_selection_info(void)
{
if (!guard_contexts) {
guard_contexts = smartlist_new();
}
if (!curr_guard_context) {
curr_guard_context = guard_selection_new();
smartlist_add(guard_contexts, curr_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;
}
/** Return an interval betweeen 'now' and 'max_backdate' seconds in the past,
* chosen uniformly at random. */
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);
}
/**
* DOCDOC
*/
STATIC void
entry_guard_add_to_sample(guard_selection_t *gs,
node_t *node)
{
(void) entry_guard_add_to_sample; // XXXX prop271 remove -- unused
const int GUARD_LIFETIME = 90 * 86400; // xxxx prop271
tor_assert(gs);
tor_assert(node);
// XXXX prop271 take ed25519 identity here too.
/* make sure that the guard is not already sampled. */
SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards,
entry_guard_t *, sampled) {
if (BUG(tor_memeq(node->identity, sampled->identity, DIGEST_LEN))) {
return;
}
} SMARTLIST_FOREACH_END(sampled);
entry_guard_t *guard = tor_malloc_zero(sizeof(entry_guard_t));
/* persistent fields */
memcpy(guard->identity, node->identity, DIGEST_LEN);
strlcpy(guard->nickname, node_get_nickname(node), 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->confirmed_idx = -1;
/* non-persistent fields */
guard->is_reachable = GUARD_REACHABLE_MAYBE;
smartlist_add(gs->sampled_entry_guards, guard);
gs->filtered_up_to_date = 0;
entry_guards_changed_for_guard_selection(gs);
}
/**
* 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, "rsa_id=%s",
hex_str(guard->identity, DIGEST_LEN));
if (strlen(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);
}
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 *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;
/* 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
strmap_set(vals, "rsa_id", &rsa_id);
strmap_set(vals, "nickname", &nickname);
strmap_set(vals, "sampled_on", &sampled_on);
strmap_set(vals, "sampled_by", &sampled_by);
strmap_set(vals, "unlisted_since", &unlisted_since);
strmap_set(vals, "listed", &listed);
strmap_set(vals, "confirmed_on", &confirmed_on);
strmap_set(vals, "confirmed_idx", &confirmed_idx);
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));
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);
}
/* 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 */
/* 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_CIRC, "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;
goto done;
err:
// only consider it an error if the guard state was totally unparseable.
entry_guard_free(guard);
guard = NULL;
done:
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);
SMARTLIST_FOREACH(extra, char *, cp, tor_free(cp));
smartlist_free(extra);
return guard;
}
/** 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->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
}
/** Largest amount that we'll backdate chosen_on_date */
#define CHOSEN_ON_DATE_SLOP (30*86400)
/** 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);
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));
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);
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.*/
void
add_bridge_as_entry_guard(guard_selection_t *gs,
const node_t *chosen)
{
add_an_entry_guard(gs, chosen, 1, 1, 0, 0);
}
/** 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);
}
/** 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);
}
/** 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)
/** Release all storage held by e. */
STATIC void
entry_guard_free(entry_guard_t *e)
{
if (!e)
return;
tor_free(e->chosen_by_version);
tor_free(e->sampled_by_version);
tor_free(e->extra_state_fields);
tor_free(e);
}
/**
* 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;
}
/** 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)
{
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 (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;
}
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)
{
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)
{
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;
tor_assert(get_options()->UseBridges);
(void) choose_random_entry_impl(get_guard_selection_info(),
NULL, 0, 0, &n_options);
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;
}
/** 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();
if (0) entry_guard_parse_from_state(NULL); // XXXX prop271 remove -- unused
if (0) entry_guard_add_to_sample(NULL, NULL); // XXXX prop271 remove
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;
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")) {
const or_options_t *options = get_options();
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);
/* 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 (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);
}
} else if (!strcasecmp(line->key, "EntryGuardPathBias")) {
const or_options_t *options = get_options();
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);
/* 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 (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);
}
} 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;
gs->dirty = 0;
/* 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))
gs->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)
{
return entry_guards_parse_state_for_guard_selection(
get_guard_selection_info(),
state, set, msg);
}
/** 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);
gs->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(). */
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.
*
* XXX this should get totally redesigned around storing multiple
* entry guard contexts. For the initial refactor we'll just
* always use the current default. Fix it as soon as we actually
* have any way that default can change.
*/
void
entry_guards_update_state(or_state_t *state)
{
config_line_t **next, *line;
guard_selection_t *gs = get_guard_selection_info();
if (0) entry_guard_encode_for_state(NULL); // XXXX prop271 remove -- unused
tor_assert(gs != NULL);
tor_assert(gs->chosen_entry_guards != NULL);
if (!gs->dirty)
return;
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);
gs->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;
}
/** 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;
}
/* 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);
}
/** Free one guard selection context */
static void
guard_selection_free(guard_selection_t *gs)
{
if (!gs) return;
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;
}
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());
}