/* Copyright (c) 2001 Matej Pfajfar.
* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2017, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file entrynodes.h
* \brief Header file for circuitbuild.c.
**/
#ifndef TOR_ENTRYNODES_H
#define TOR_ENTRYNODES_H
#include "handles.h"
/* Forward declare for guard_selection_t; entrynodes.c has the real struct */
typedef struct guard_selection_s guard_selection_t;
/* Forward declare for entry_guard_t; the real declaration is private. */
typedef struct entry_guard_t entry_guard_t;
/* Forward declaration for circuit_guard_state_t; the real declaration is
private. */
typedef struct circuit_guard_state_t circuit_guard_state_t;
/* Forward declaration for entry_guard_restriction_t; the real declaration is
private. */
typedef struct entry_guard_restriction_t entry_guard_restriction_t;
/* Information about a guard's pathbias status.
* These fields are used in circpathbias.c to try to detect entry
* nodes that are failing circuits at a suspicious frequency.
*/
typedef struct guard_pathbias_t {
unsigned int path_bias_noticed : 1; /**< Did we alert the user about path
* bias for this node already? */
unsigned int path_bias_warned : 1; /**< Did we alert the user about path bias
* for this node already? */
unsigned int path_bias_extreme : 1; /**< Did we alert the user about path
* bias for this node already? */
unsigned int path_bias_disabled : 1; /**< Have we disabled this node because
* of path bias issues? */
unsigned int path_bias_use_noticed : 1; /**< Did we alert the user about path
* use bias for this node already? */
unsigned int path_bias_use_extreme : 1; /**< Did we alert the user about path
* use bias for this node already? */
double circ_attempts; /**< Number of circuits this guard has "attempted" */
double circ_successes; /**< Number of successfully built circuits using
* this guard as first hop. */
double successful_circuits_closed; /**< Number of circuits that carried
* streams successfully. */
double collapsed_circuits; /**< Number of fully built circuits that were
* remotely closed before any streams were
* attempted. */
double unusable_circuits; /**< Number of circuits for which streams were
* attempted, but none succeeded. */
double timeouts; /**< Number of 'right-censored' circuit timeouts for this
* guard. */
double use_attempts; /**< Number of circuits we tried to use with streams */
double use_successes; /**< Number of successfully used circuits using
* this guard as first hop. */
} guard_pathbias_t;
#if defined(ENTRYNODES_PRIVATE)
/**
* @name values for entry_guard_t.is_reachable.
*
* See entry_guard_t.is_reachable for more information.
*/
/**@{*/
#define GUARD_REACHABLE_NO 0
#define GUARD_REACHABLE_YES 1
#define GUARD_REACHABLE_MAYBE 2
/**@}*/
/** An entry_guard_t represents our information about a chosen long-term
* first hop, known as a "helper" node in the literature. We can't just
* use a node_t, since we want to remember these even when we
* don't have any directory info. */
struct entry_guard_t {
HANDLE_ENTRY(entry_guard, entry_guard_t);
char nickname[MAX_HEX_NICKNAME_LEN+1];
char identity[DIGEST_LEN];
ed25519_public_key_t ed_id;
/**
* @name new guard selection algorithm fields.
*
* Only the new (prop271) algorithm uses these. For a more full
* description of the algorithm, see the module documentation for
* entrynodes.c
*/
/**@{*/
/* == Persistent fields, present for all sampled guards. */
/** When was this guard added to the sample? */
time_t sampled_on_date;
/** Since what date has this guard been "unlisted"? A guard counts as
* unlisted if we have a live consensus that does not include it, or
* if we have a live consensus that does not include it as a usable
* guard. This field is zero when the guard is listed. */
time_t unlisted_since_date; // can be zero
/** What version of Tor added this guard to the sample? */
char *sampled_by_version;
/** Is this guard listed right now? If this is set, then
* unlisted_since_date should be set too. */
unsigned currently_listed : 1;
/* == Persistent fields, for confirmed guards only */
/** When was this guard confirmed? (That is, when did we first use it
* successfully and decide to keep it?) This field is zero if this is not a
* confirmed guard. */
time_t confirmed_on_date; /* 0 if not confirmed */
/**
* In what order was this guard confirmed? Guards with lower indices
* appear earlier on the confirmed list. If the confirmed list is compacted,
* this field corresponds to the index of this guard on the confirmed list.
*
* This field is set to -1 if this guard is not confirmed.
*/
int confirmed_idx; /* -1 if not confirmed; otherwise the order that this
* item should occur in the CONFIRMED_GUARDS ordered
* list */
/**
* Which selection does this guard belong to?
*/
char *selection_name;
/** Bridges only: address of the bridge. */
tor_addr_port_t *bridge_addr;
/* ==== Non-persistent fields. */
/* == These are used by sampled guards */
/** When did we last decide to try using this guard for a circuit? 0 for
* "not since we started up." */
time_t last_tried_to_connect;
/** How reachable do we consider this guard to be? One of
* GUARD_REACHABLE_NO, GUARD_REACHABLE_YES, or GUARD_REACHABLE_MAYBE. */
unsigned is_reachable : 2;
/** Boolean: true iff this guard is pending. A pending guard is one
* that we have an in-progress circuit through, and which we do not plan
* to try again until it either succeeds or fails. Primary guards can
* never be pending. */
unsigned is_pending : 1;
/** If true, don't write this guard to disk. (Used for bridges with unknown
* identities) */
unsigned is_persistent : 1;
/** When did we get the earliest connection failure for this guard?
* We clear this field on a successful connect. We do _not_ clear it
* when we mark the guard as "MAYBE" reachable.
*/
time_t failing_since;
/* == Set inclusion flags. */
/** If true, this guard is in the filtered set. The filtered set includes
* all sampled guards that our configuration allows us to use. */
unsigned is_filtered_guard : 1;
/** If true, this guard is in the usable filtered set. The usable filtered
* set includes all filtered guards that are not believed to be
* unreachable. (That is, those for which is_reachable is not
* GUARD_REACHABLE_NO) */
unsigned is_usable_filtered_guard : 1;
unsigned is_primary:1;
/** This string holds any fields that we are maintaining because
* we saw them in the state, even if we don't understand them. */
char *extra_state_fields;
/** Backpointer to the guard selection that this guard belongs to.
* The entry_guard_t must never outlive its guard_selection. */
guard_selection_t *in_selection;
/**@}*/
/** Path bias information for this guard. */
guard_pathbias_t pb;
};
/**
* Possible rules for a guard selection to follow
*/
typedef enum guard_selection_type_t {
/** Infer the type of this selection from its name. */
GS_TYPE_INFER=0,
/** Use the normal guard selection algorithm, taking our sample from the
* complete list of guards in the consensus. */
GS_TYPE_NORMAL=1,
/** Use the normal guard selection algorithm, taking our sample from the
* configured bridges, and allowing it to grow as large as all the configured
* bridges */
GS_TYPE_BRIDGE,
/** Use the normal guard selection algorithm, taking our sample from the
* set of filtered nodes. */
GS_TYPE_RESTRICTED,
} guard_selection_type_t;
/**
* All of the the context for guard selection on a particular client.
*
* We maintain multiple guard selection contexts for a client, depending
* aspects on its current configuration -- whether an extremely
* restrictive EntryNodes is used, whether UseBridges is enabled, and so
* on.)
*
* See the module documentation for entrynodes.c for more information
* about guard selection algorithms.
*/
struct guard_selection_s {
/**
* The name for this guard-selection object. (Must not contain spaces).
*/
char *name;
/**
* What rules does this guard-selection object follow?
*/
guard_selection_type_t type;
/**
* A value of 1 means that primary_entry_guards is up-to-date with respect to
* the consensus and status info that we currently have; 0 means we need to
* recalculate it before using primary_entry_guards or the is_primary flag on
* any guard.
*/
int primary_guards_up_to_date;
/**
* A list of the sampled entry guards, as entry_guard_t structures.
* Not in any particular order. When we 'sample' a guard, we are
* noting it as a possible guard to pick in the future. The use of
* sampling here prevents us from being forced by an attacker to try
* every guard on the network. This list is persistent.
*/
smartlist_t *sampled_entry_guards;
/**
* Ordered list (from highest to lowest priority) of guards that we
* have successfully contacted and decided to use. Every member of
* this list is a member of sampled_entry_guards. Every member should
* have confirmed_on_date set, and have confirmed_idx greater than
* any earlier member of the list.
*
* This list is persistent. It is a subset of the elements in
* sampled_entry_guards, and its pointers point to elements of
* sampled_entry_guards.
*/
smartlist_t *confirmed_entry_guards;
/**
* Ordered list (from highest to lowest priority) of guards that we
* are willing to use the most happily. These guards may or may not
* yet be confirmed yet. If we can use one of these guards, we are
* probably not on a network that is trying to restrict our guard
* choices.
*
* This list is a subset of the elements in
* sampled_entry_guards, and its pointers point to elements of
* sampled_entry_guards.
*/
smartlist_t *primary_entry_guards;
/** When did we last successfully build a circuit or use a circuit? */
time_t last_time_on_internet;
/** What confirmed_idx value should the next-added member of
* confirmed_entry_guards receive? */
int next_confirmed_idx;
};
struct entry_guard_handle_t;
/** Types of restrictions we impose when picking guard nodes */
typedef enum guard_restriction_type_t {
/* Don't pick the same guard node as our exit node (or its family) */
RST_EXIT_NODE = 0,
/* Don't pick dirguards that have previously shown to be outdated */
RST_OUTDATED_MD_DIRSERVER = 1
} guard_restriction_type_t;
/**
* A restriction to remember which entry guards are off-limits for a given
* circuit.
*
* Note: This mechanism is NOT for recording which guards are never to be
* used: only which guards cannot be used on one particular circuit.
*/
struct entry_guard_restriction_t {
/* What type of restriction are we imposing? */
guard_restriction_type_t type;
/* In case of restriction type RST_EXIT_NODE, the guard's RSA identity
* digest must not equal this; and it must not be in the same family as any
* node with this digest. */
uint8_t exclude_id[DIGEST_LEN];
};
/**
* Per-circuit state to track whether we'll be able to use the circuit.
*/
struct circuit_guard_state_t {
/** Handle to the entry guard object for this circuit. */
struct entry_guard_handle_t *guard;
/** The time at which state last changed. */
time_t state_set_at;
/** One of GUARD_CIRC_STATE_* */
uint8_t state;
/**
* A set of restrictions that were placed on this guard when we selected it
* for this particular circuit. We need to remember the restrictions here,
* since any guard that breaks these restrictions will not block this
* circuit from becoming COMPLETE.
*/
entry_guard_restriction_t *restrictions;
};
#endif /* defined(ENTRYNODES_PRIVATE) */
/* Common entry points for old and new guard code */
int guards_update_all(void);
const node_t *guards_choose_guard(cpath_build_state_t *state,
circuit_guard_state_t **guard_state_out);
const node_t *guards_choose_dirguard(uint8_t dir_purpose,
circuit_guard_state_t **guard_state_out);
#if 1
/* XXXX NM I would prefer that all of this stuff be private to
* entrynodes.c. */
entry_guard_t *entry_guard_get_by_id_digest_for_guard_selection(
guard_selection_t *gs, const char *digest);
entry_guard_t *entry_guard_get_by_id_digest(const char *digest);
circuit_guard_state_t *
get_guard_state_for_bridge_desc_fetch(const char *digest);
void entry_guards_changed_for_guard_selection(guard_selection_t *gs);
void entry_guards_changed(void);
guard_selection_t * get_guard_selection_info(void);
int num_live_entry_guards_for_guard_selection(
guard_selection_t *gs,
int for_directory);
int num_live_entry_guards(int for_directory);
#endif /* 1 */
const node_t *entry_guard_find_node(const entry_guard_t *guard);
const char *entry_guard_get_rsa_id_digest(const entry_guard_t *guard);
const char *entry_guard_describe(const entry_guard_t *guard);
guard_pathbias_t *entry_guard_get_pathbias_state(entry_guard_t *guard);
/** Enum to specify how we're going to use a given guard, when we're picking
* one for immediate use. */
typedef enum {
GUARD_USAGE_TRAFFIC = 0,
GUARD_USAGE_DIRGUARD = 1
} guard_usage_t;
#define circuit_guard_state_free(val) \
FREE_AND_NULL(circuit_guard_state_t, circuit_guard_state_free_, (val))
void circuit_guard_state_free_(circuit_guard_state_t *state);
int entry_guard_pick_for_circuit(guard_selection_t *gs,
guard_usage_t usage,
entry_guard_restriction_t *rst,
const node_t **chosen_node_out,
circuit_guard_state_t **guard_state_out);
/* We just connected to an entry guard. What should we do with the circuit? */
typedef enum {
GUARD_USABLE_NEVER = -1, /* Never use the circuit */
GUARD_MAYBE_USABLE_LATER = 0, /* Keep it. We might use it in the future */
GUARD_USABLE_NOW = 1, /* Use it right now */
} guard_usable_t;
guard_usable_t entry_guard_succeeded(circuit_guard_state_t **guard_state_p);
void entry_guard_failed(circuit_guard_state_t **guard_state_p);
void entry_guard_cancel(circuit_guard_state_t **guard_state_p);
void entry_guard_chan_failed(channel_t *chan);
int entry_guards_update_all(guard_selection_t *gs);
int entry_guards_upgrade_waiting_circuits(guard_selection_t *gs,
const smartlist_t *all_circuits,
smartlist_t *newly_complete_out);
int entry_guard_state_should_expire(circuit_guard_state_t *guard_state);
void entry_guards_note_internet_connectivity(guard_selection_t *gs);
int update_guard_selection_choice(const or_options_t *options);
int entry_guard_could_succeed(const circuit_guard_state_t *guard_state);
MOCK_DECL(int,num_bridges_usable,(int use_maybe_reachable));
#ifdef ENTRYNODES_PRIVATE
/**
* @name Default values for the parameters for the new (prop271) entry guard
* algorithm.
*/
/**@{*/
/**
* We never let our sampled guard set grow larger than this percentage
* of the guards on the network.
*/
#define DFLT_MAX_SAMPLE_THRESHOLD_PERCENT 20
/**
* We never let our sampled guard set grow larger than this number of
* guards.
*/
#define DFLT_MAX_SAMPLE_SIZE 60
/**
* We always try to make our sample contain at least this many guards.
*/
#define DFLT_MIN_FILTERED_SAMPLE_SIZE 20
/**
* If a guard is unlisted for this many days in a row, we remove it.
*/
#define DFLT_REMOVE_UNLISTED_GUARDS_AFTER_DAYS 20
/**
* We remove unconfirmed guards from the sample after this many days,
* regardless of whether they are listed or unlisted.
*/
#define DFLT_GUARD_LIFETIME_DAYS 120
/**
* We remove confirmed guards from the sample if they were sampled
* GUARD_LIFETIME_DAYS ago and confirmed this many days ago.
*/
#define DFLT_GUARD_CONFIRMED_MIN_LIFETIME_DAYS 60
/**
* How many guards do we try to keep on our primary guard list?
*/
#define DFLT_N_PRIMARY_GUARDS 3
/**
* Of the live guards on the primary guard list, how many do we consider when
* choosing a guard to use?
*/
#define DFLT_N_PRIMARY_GUARDS_TO_USE 1
/**
* As DFLT_N_PRIMARY_GUARDS, but for choosing which directory guard to use.
*/
#define DFLT_N_PRIMARY_DIR_GUARDS_TO_USE 3
/**
* If we haven't successfully built or used a circuit in this long, then
* consider that the internet is probably down.
*/
#define DFLT_INTERNET_LIKELY_DOWN_INTERVAL (10*60)
/**
* 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.
*/
#define DFLT_NONPRIMARY_GUARD_CONNECT_TIMEOUT 15
/**
* If a circuit has been sitting around in 'waiting for better guard' state
* for at least this long, we'll expire it.
*/
#define DFLT_NONPRIMARY_GUARD_IDLE_TIMEOUT (10*60)
/**
* If our configuration retains fewer than this fraction of guards from the
* torrc, we are in a restricted setting.
*/
#define DFLT_MEANINGFUL_RESTRICTION_PERCENT 20
/**
* If our configuration retains fewer than this fraction of guards from the
* torrc, we are in an extremely restricted setting, and should warn.
*/
#define DFLT_EXTREME_RESTRICTION_PERCENT 1
/**@}*/
STATIC double get_max_sample_threshold(void);
STATIC int get_max_sample_size_absolute(void);
STATIC int get_min_filtered_sample_size(void);
STATIC int get_remove_unlisted_guards_after_days(void);
STATIC int get_guard_lifetime(void);
STATIC int get_guard_confirmed_min_lifetime(void);
STATIC int get_n_primary_guards(void);
STATIC int get_n_primary_guards_to_use(guard_usage_t usage);
STATIC int get_internet_likely_down_interval(void);
STATIC int get_nonprimary_guard_connect_timeout(void);
STATIC int get_nonprimary_guard_idle_timeout(void);
STATIC double get_meaningful_restriction_threshold(void);
STATIC double get_extreme_restriction_threshold(void);
HANDLE_DECL(entry_guard, entry_guard_t, STATIC)
#define entry_guard_handle_free(h) \
FREE_AND_NULL(entry_guard_handle_t, entry_guard_handle_free_, (h))
STATIC guard_selection_type_t guard_selection_infer_type(
guard_selection_type_t type_in,
const char *name);
STATIC guard_selection_t *guard_selection_new(const char *name,
guard_selection_type_t type);
STATIC guard_selection_t *get_guard_selection_by_name(
const char *name, guard_selection_type_t type, int create_if_absent);
STATIC void guard_selection_free_(guard_selection_t *gs);
#define guard_selection_free(gs) \
FREE_AND_NULL(guard_selection_t, guard_selection_free_, (gs))
MOCK_DECL(STATIC int, entry_guard_is_listed,
(guard_selection_t *gs, const entry_guard_t *guard));
STATIC const char *choose_guard_selection(const or_options_t *options,
const networkstatus_t *ns,
const guard_selection_t *old_selection,
guard_selection_type_t *type_out);
STATIC entry_guard_t *get_sampled_guard_with_id(guard_selection_t *gs,
const uint8_t *rsa_id);
MOCK_DECL(STATIC time_t, randomize_time, (time_t now, time_t max_backdate));
MOCK_DECL(STATIC circuit_guard_state_t *,
circuit_guard_state_new,(entry_guard_t *guard, unsigned state,
entry_guard_restriction_t *rst));
STATIC entry_guard_t *entry_guard_add_to_sample(guard_selection_t *gs,
const node_t *node);
STATIC entry_guard_t *entry_guards_expand_sample(guard_selection_t *gs);
STATIC char *entry_guard_encode_for_state(entry_guard_t *guard);
STATIC entry_guard_t *entry_guard_parse_from_state(const char *s);
#define entry_guard_free(e) \
FREE_AND_NULL(entry_guard_t, entry_guard_free_, (e))
STATIC void entry_guard_free_(entry_guard_t *e);
STATIC void entry_guards_update_filtered_sets(guard_selection_t *gs);
STATIC int entry_guards_all_primary_guards_are_down(guard_selection_t *gs);
/**
* @name Flags for sample_reachable_filtered_entry_guards()
*/
/**@{*/
#define SAMPLE_EXCLUDE_CONFIRMED (1u<<0)
#define SAMPLE_EXCLUDE_PRIMARY (1u<<1)
#define SAMPLE_EXCLUDE_PENDING (1u<<2)
#define SAMPLE_NO_UPDATE_PRIMARY (1u<<3)
#define SAMPLE_EXCLUDE_NO_DESCRIPTOR (1u<<4)
/**@}*/
STATIC entry_guard_t *sample_reachable_filtered_entry_guards(
guard_selection_t *gs,
const entry_guard_restriction_t *rst,
unsigned flags);
STATIC void entry_guard_consider_retry(entry_guard_t *guard);
STATIC void make_guard_confirmed(guard_selection_t *gs, entry_guard_t *guard);
STATIC void entry_guards_update_confirmed(guard_selection_t *gs);
STATIC void entry_guards_update_primary(guard_selection_t *gs);
STATIC int num_reachable_filtered_guards(const guard_selection_t *gs,
const entry_guard_restriction_t *rst);
STATIC void sampled_guards_update_from_consensus(guard_selection_t *gs);
/**
* @name Possible guard-states for a circuit.
*/
/**@{*/
/** State for a circuit that can (so far as the guard subsystem is
* concerned) be used for actual traffic as soon as it is successfully
* opened. */
#define GUARD_CIRC_STATE_USABLE_ON_COMPLETION 1
/** State for an non-open circuit that we shouldn't use for actual
* traffic, when it completes, unless other circuits to preferable
* guards fail. */
#define GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD 2
/** State for an open circuit that we shouldn't use for actual traffic
* unless other circuits to preferable guards fail. */
#define GUARD_CIRC_STATE_WAITING_FOR_BETTER_GUARD 3
/** State for a circuit that can (so far as the guard subsystem is
* concerned) be used for actual traffic. */
#define GUARD_CIRC_STATE_COMPLETE 4
/** State for a circuit that is unusable, and will not become usable. */
#define GUARD_CIRC_STATE_DEAD 5
/**@}*/
STATIC void entry_guards_note_guard_failure(guard_selection_t *gs,
entry_guard_t *guard);
STATIC entry_guard_t *select_entry_guard_for_circuit(guard_selection_t *gs,
guard_usage_t usage,
const entry_guard_restriction_t *rst,
unsigned *state_out);
STATIC void mark_primary_guards_maybe_reachable(guard_selection_t *gs);
STATIC unsigned entry_guards_note_guard_success(guard_selection_t *gs,
entry_guard_t *guard,
unsigned old_state);
STATIC int entry_guard_has_higher_priority(entry_guard_t *a, entry_guard_t *b);
STATIC char *getinfo_helper_format_single_entry_guard(const entry_guard_t *e);
STATIC entry_guard_restriction_t *guard_create_exit_restriction(
const uint8_t *exit_id);
STATIC entry_guard_restriction_t *guard_create_dirserver_md_restriction(void);
STATIC void entry_guard_restriction_free_(entry_guard_restriction_t *rst);
#define entry_guard_restriction_free(rst) \
FREE_AND_NULL(entry_guard_restriction_t, \
entry_guard_restriction_free_, (rst))
#endif /* defined(ENTRYNODES_PRIVATE) */
void remove_all_entry_guards_for_guard_selection(guard_selection_t *gs);
void remove_all_entry_guards(void);
struct bridge_info_t;
void entry_guard_learned_bridge_identity(const tor_addr_port_t *addrport,
const uint8_t *rsa_id_digest);
int entry_list_is_constrained(const or_options_t *options);
int guards_retry_optimistic(const or_options_t *options);
int entry_guards_parse_state_for_guard_selection(
guard_selection_t *gs, or_state_t *state, int set, char **msg);
int entry_guards_parse_state(or_state_t *state, int set, char **msg);
void entry_guards_update_state(or_state_t *state);
int getinfo_helper_entry_guards(control_connection_t *conn,
const char *question, char **answer,
const char **errmsg);
int entries_known_but_down(const or_options_t *options);
void entries_retry_all(const or_options_t *options);
char *entry_guards_get_err_str_if_dir_info_missing(int using_mds,
int num_present, int num_usable);
char *guard_selection_get_err_str_if_dir_info_missing(guard_selection_t *gs,
int using_mds,
int num_present, int num_usable);
void entry_guards_free_all(void);
double pathbias_get_close_success_count(entry_guard_t *guard);
double pathbias_get_use_success_count(entry_guard_t *guard);
/** Contains the bandwidth of a relay as a guard and as a non-guard
* after the guardfraction has been considered. */
typedef struct guardfraction_bandwidth_t {
/** Bandwidth as a guard after guardfraction has been considered. */
int guard_bw;
/** Bandwidth as a non-guard after guardfraction has been considered. */
int non_guard_bw;
} guardfraction_bandwidth_t;
int should_apply_guardfraction(const networkstatus_t *ns);
void
guard_get_guardfraction_bandwidth(guardfraction_bandwidth_t *guardfraction_bw,
int orig_bandwidth,
uint32_t guardfraction_percentage);
#endif /* !defined(TOR_ENTRYNODES_H) */