/* Copyright (c) 2001 Matej Pfajfar.
* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2008, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/* $Id$ */
const char circuitbuild_c_id[] =
"$Id$";
/**
* \file circuitbuild.c
* \brief The actual details of building circuits.
**/
#include "or.h"
/********* START VARIABLES **********/
/** A global list of all circuits at this hop. */
extern circuit_t *global_circuitlist;
/** 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 routerinfo_t, since we want to remember these even when we
* don't have a directory. */
typedef struct {
char nickname[MAX_NICKNAME_LEN+1];
char identity[DIGEST_LEN];
time_t chosen_on_date; /**< Approximately when was this guard added?
* "0" if we don't know. */
char *chosen_by_version; /**< What tor version added this guard? NULL
* if we don't know. */
unsigned int made_contact : 1; /**< 0 if we have never connected to this
* router, 1 if we have. */
unsigned int can_retry : 1; /**< Should we retry connecting to this entry,
* in spite of having it marked as unreachable?*/
time_t bad_since; /**< 0 if this guard is currently usable, or the time at
* which it was observed to become (according to the
* directory or the user configuration) unusable. */
time_t unreachable_since; /**< 0 if we can connect to this guard, or the
* time at which we first noticed we couldn't
* connect to it. */
time_t last_attempted; /**< 0 if we can connect to this guard, or the time
* at which we last failed to connect to it. */
} entry_guard_t;
/** A list of our chosen entry guards. */
static smartlist_t *entry_guards = NULL;
/** A value of 1 means that the entry_guards list has changed
* and those changes need to be flushed to disk. */
static int entry_guards_dirty = 0;
/********* END VARIABLES ************/
static int circuit_deliver_create_cell(circuit_t *circ,
uint8_t cell_type, const char *payload);
static int onion_pick_cpath_exit(origin_circuit_t *circ, extend_info_t *exit);
static crypt_path_t *onion_next_hop_in_cpath(crypt_path_t *cpath);
static int onion_extend_cpath(origin_circuit_t *circ);
static int count_acceptable_routers(smartlist_t *routers);
static int onion_append_hop(crypt_path_t **head_ptr, extend_info_t *choice);
static void entry_guards_changed(void);
static time_t start_of_month(time_t when);
/** Iterate over values of circ_id, starting from conn-\>next_circ_id,
* and with the high bit specified by conn-\>circ_id_type, until we get
* a circ_id that is not in use by any other circuit on that conn.
*
* Return it, or 0 if can't get a unique circ_id.
*/
static uint16_t
get_unique_circ_id_by_conn(or_connection_t *conn)
{
uint16_t test_circ_id;
uint16_t attempts=0;
uint16_t high_bit;
tor_assert(conn);
if (conn->circ_id_type == CIRC_ID_TYPE_NEITHER) {
log_warn(LD_BUG, "Trying to pick a circuit ID for a connection from "
"a client with no identity.");
return 0;
}
high_bit = (conn->circ_id_type == CIRC_ID_TYPE_HIGHER) ? 1<<15 : 0;
do {
/* Sequentially iterate over test_circ_id=1...1<<15-1 until we find a
* circID such that (high_bit|test_circ_id) is not already used. */
test_circ_id = conn->next_circ_id++;
if (test_circ_id == 0 || test_circ_id >= 1<<15) {
test_circ_id = 1;
conn->next_circ_id = 2;
}
if (++attempts > 1<<15) {
/* Make sure we don't loop forever if all circ_id's are used. This
* matters because it's an external DoS opportunity.
*/
log_warn(LD_CIRC,"No unused circ IDs. Failing.");
return 0;
}
test_circ_id |= high_bit;
} while (circuit_get_by_circid_orconn(test_circ_id, conn));
return test_circ_id;
}
/** If verbose is false, allocate and return a comma-separated list of
* the currently built elements of circuit_t. If verbose is true, also
* list information about link status in a more verbose format using spaces.
* If verbose_names is false, give nicknames for Named routers and hex
* digests for others; if verbose_names is true, use $DIGEST=Name style
* names.
*/
static char *
circuit_list_path_impl(origin_circuit_t *circ, int verbose, int verbose_names)
{
crypt_path_t *hop;
smartlist_t *elements;
const char *states[] = {"closed", "waiting for keys", "open"};
char buf[128];
char *s;
elements = smartlist_create();
if (verbose) {
const char *nickname = build_state_get_exit_nickname(circ->build_state);
tor_snprintf(buf, sizeof(buf), "%s%s circ (length %d%s%s):",
circ->build_state->is_internal ? "internal" : "exit",
circ->build_state->need_uptime ? " (high-uptime)" : "",
circ->build_state->desired_path_len,
circ->_base.state == CIRCUIT_STATE_OPEN ? "" : ", exit ",
circ->_base.state == CIRCUIT_STATE_OPEN ? "" :
(nickname?nickname:"*unnamed*"));
smartlist_add(elements, tor_strdup(buf));
}
hop = circ->cpath;
do {
routerinfo_t *ri;
char *elt;
if (!hop)
break;
if (!verbose && hop->state != CPATH_STATE_OPEN)
break;
if (!hop->extend_info)
break;
if (verbose_names) {
elt = tor_malloc(MAX_VERBOSE_NICKNAME_LEN+1);
if ((ri = router_get_by_digest(hop->extend_info->identity_digest))) {
router_get_verbose_nickname(elt, ri);
} else if (hop->extend_info->nickname &&
is_legal_nickname(hop->extend_info->nickname)) {
elt[0] = '$';
base16_encode(elt+1, HEX_DIGEST_LEN+1,
hop->extend_info->identity_digest, DIGEST_LEN);
elt[HEX_DIGEST_LEN+1]= '~';
strlcpy(elt+HEX_DIGEST_LEN+2,
hop->extend_info->nickname, MAX_NICKNAME_LEN+1);
} else {
elt[0] = '$';
base16_encode(elt+1, HEX_DIGEST_LEN+1,
hop->extend_info->identity_digest, DIGEST_LEN);
}
} else { /* ! verbose_names */
if ((ri = router_get_by_digest(hop->extend_info->identity_digest)) &&
ri->is_named) {
elt = tor_strdup(hop->extend_info->nickname);
} else {
elt = tor_malloc(HEX_DIGEST_LEN+2);
elt[0] = '$';
base16_encode(elt+1, HEX_DIGEST_LEN+1,
hop->extend_info->identity_digest, DIGEST_LEN);
}
}
tor_assert(elt);
if (verbose) {
size_t len = strlen(elt)+2+strlen(states[hop->state])+1;
char *v = tor_malloc(len);
tor_assert(hop->state <= 2);
tor_snprintf(v,len,"%s(%s)",elt,states[hop->state]);
smartlist_add(elements, v);
tor_free(elt);
} else {
smartlist_add(elements, elt);
}
hop = hop->next;
} while (hop != circ->cpath);
s = smartlist_join_strings(elements, verbose?" ":",", 0, NULL);
SMARTLIST_FOREACH(elements, char*, cp, tor_free(cp));
smartlist_free(elements);
return s;
}
/** If verbose is false, allocate and return a comma-separated
* list of the currently built elements of circuit_t. If
* verbose is true, also list information about link status in
* a more verbose format using spaces.
*/
char *
circuit_list_path(origin_circuit_t *circ, int verbose)
{
return circuit_list_path_impl(circ, verbose, 0);
}
/** Allocate and return a comma-separated list of the currently built elements
* of circuit_t, giving each as a verbose nickname.
*/
char *
circuit_list_path_for_controller(origin_circuit_t *circ)
{
return circuit_list_path_impl(circ, 0, 1);
}
/** Log, at severity severity, the nicknames of each router in
* circ's cpath. Also log the length of the cpath, and the intended
* exit point.
*/
void
circuit_log_path(int severity, unsigned int domain, origin_circuit_t *circ)
{
char *s = circuit_list_path(circ,1);
log(severity,domain,"%s",s);
tor_free(s);
}
/** Tell the rep(utation)hist(ory) module about the status of the links
* in circ. Hops that have become OPEN are marked as successfully
* extended; the _first_ hop that isn't open (if any) is marked as
* unable to extend.
*/
/* XXXX Someday we should learn from OR circuits too. */
void
circuit_rep_hist_note_result(origin_circuit_t *circ)
{
crypt_path_t *hop;
char *prev_digest = NULL;
routerinfo_t *router;
hop = circ->cpath;
if (!hop) /* circuit hasn't started building yet. */
return;
if (server_mode(get_options())) {
routerinfo_t *me = router_get_my_routerinfo();
if (!me)
return;
prev_digest = me->cache_info.identity_digest;
}
do {
router = router_get_by_digest(hop->extend_info->identity_digest);
if (router) {
if (prev_digest) {
if (hop->state == CPATH_STATE_OPEN)
rep_hist_note_extend_succeeded(prev_digest,
router->cache_info.identity_digest);
else {
rep_hist_note_extend_failed(prev_digest,
router->cache_info.identity_digest);
break;
}
}
prev_digest = router->cache_info.identity_digest;
} else {
prev_digest = NULL;
}
hop=hop->next;
} while (hop!=circ->cpath);
}
/** Pick all the entries in our cpath. Stop and return 0 when we're
* happy, or return -1 if an error occurs. */
static int
onion_populate_cpath(origin_circuit_t *circ)
{
int r;
again:
r = onion_extend_cpath(circ);
if (r < 0) {
log_info(LD_CIRC,"Generating cpath hop failed.");
return -1;
}
if (r == 0)
goto again;
return 0; /* if r == 1 */
}
/** Create and return a new origin circuit. Initialize its purpose and
* build-state based on our arguments. The flags argument is a
* bitfield of CIRCLAUNCH_* flags. */
origin_circuit_t *
origin_circuit_init(uint8_t purpose, int flags)
{
/* sets circ->p_circ_id and circ->p_conn */
origin_circuit_t *circ = origin_circuit_new();
circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_OR_WAIT);
circ->build_state = tor_malloc_zero(sizeof(cpath_build_state_t));
circ->build_state->onehop_tunnel =
((flags & CIRCLAUNCH_ONEHOP_TUNNEL) ? 1 : 0);
circ->build_state->need_uptime =
((flags & CIRCLAUNCH_NEED_UPTIME) ? 1 : 0);
circ->build_state->need_capacity =
((flags & CIRCLAUNCH_NEED_CAPACITY) ? 1 : 0);
circ->build_state->is_internal =
((flags & CIRCLAUNCH_IS_INTERNAL) ? 1 : 0);
circ->_base.purpose = purpose;
return circ;
}
/** Build a new circuit for purpose. If exit
* is defined, then use that as your exit router, else choose a suitable
* exit node.
*
* Also launch a connection to the first OR in the chosen path, if
* it's not open already.
*/
origin_circuit_t *
circuit_establish_circuit(uint8_t purpose, extend_info_t *exit, int flags)
{
origin_circuit_t *circ;
int err_reason = 0;
circ = origin_circuit_init(purpose, flags);
if (onion_pick_cpath_exit(circ, exit) < 0 ||
onion_populate_cpath(circ) < 0) {
circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_NOPATH);
return NULL;
}
control_event_circuit_status(circ, CIRC_EVENT_LAUNCHED, 0);
if ((err_reason = circuit_handle_first_hop(circ)) < 0) {
circuit_mark_for_close(TO_CIRCUIT(circ), -err_reason);
return NULL;
}
return circ;
}
/** Start establishing the first hop of our circuit. Figure out what
* OR we should connect to, and if necessary start the connection to
* it. If we're already connected, then send the 'create' cell.
* Return 0 for ok, -reason if circ should be marked-for-close. */
int
circuit_handle_first_hop(origin_circuit_t *circ)
{
crypt_path_t *firsthop;
or_connection_t *n_conn;
char tmpbuf[INET_NTOA_BUF_LEN];
struct in_addr in;
int err_reason = 0;
firsthop = onion_next_hop_in_cpath(circ->cpath);
tor_assert(firsthop);
tor_assert(firsthop->extend_info);
/* now see if we're already connected to the first OR in 'route' */
in.s_addr = htonl(firsthop->extend_info->addr);
tor_inet_ntoa(&in, tmpbuf, sizeof(tmpbuf));
log_debug(LD_CIRC,"Looking for firsthop '%s:%u'",tmpbuf,
firsthop->extend_info->port);
/* imprint the circuit with its future n_conn->id */
memcpy(circ->_base.n_conn_id_digest, firsthop->extend_info->identity_digest,
DIGEST_LEN);
n_conn = connection_or_get_by_identity_digest(
firsthop->extend_info->identity_digest);
/* If we don't have an open conn, or the conn we have is obsolete
* (i.e. old or broken) and the other side will let us make a second
* connection without dropping it immediately... */
if (!n_conn || n_conn->_base.state != OR_CONN_STATE_OPEN ||
(n_conn->_base.or_is_obsolete &&
router_digest_version_as_new_as(firsthop->extend_info->identity_digest,
"0.1.1.9-alpha-cvs"))) {
/* not currently connected */
circ->_base.n_addr = firsthop->extend_info->addr;
circ->_base.n_port = firsthop->extend_info->port;
if (!n_conn || n_conn->_base.or_is_obsolete) { /* launch the connection */
n_conn = connection_or_connect(firsthop->extend_info->addr,
firsthop->extend_info->port,
firsthop->extend_info->identity_digest);
if (!n_conn) { /* connect failed, forget the whole thing */
log_info(LD_CIRC,"connect to firsthop failed. Closing.");
return -END_CIRC_REASON_CONNECTFAILED;
}
}
log_debug(LD_CIRC,"connecting in progress (or finished). Good.");
/* return success. The onion/circuit/etc will be taken care of
* automatically (may already have been) whenever n_conn reaches
* OR_CONN_STATE_OPEN.
*/
return 0;
} else { /* it's already open. use it. */
circ->_base.n_addr = n_conn->_base.addr;
circ->_base.n_port = n_conn->_base.port;
circ->_base.n_conn = n_conn;
log_debug(LD_CIRC,"Conn open. Delivering first onion skin.");
if ((err_reason = circuit_send_next_onion_skin(circ)) < 0) {
log_info(LD_CIRC,"circuit_send_next_onion_skin failed.");
return err_reason;
}
}
return 0;
}
/** Find any circuits that are waiting on or_conn to become
* open and get them to send their create cells forward.
*
* Status is 1 if connect succeeded, or 0 if connect failed.
*/
void
circuit_n_conn_done(or_connection_t *or_conn, int status)
{
smartlist_t *pending_circs;
int err_reason = 0;
log_debug(LD_CIRC,"or_conn to %s, status=%d",
or_conn->nickname ? or_conn->nickname : "NULL", status);
pending_circs = smartlist_create();
circuit_get_all_pending_on_or_conn(pending_circs, or_conn);
SMARTLIST_FOREACH(pending_circs, circuit_t *, circ,
{
/* These checks are redundant wrt get_all_pending_on_or_conn, but I'm
* leaving them in in case it's possible for the status of a circuit to
* change as we're going down the list. */
if (circ->marked_for_close || circ->n_conn ||
circ->state != CIRCUIT_STATE_OR_WAIT)
continue;
if (tor_digest_is_zero(circ->n_conn_id_digest)) {
/* Look at addr/port. This is an unkeyed connection. */
if (circ->n_addr != or_conn->_base.addr ||
circ->n_port != or_conn->_base.port)
continue;
/* now teach circ the right identity_digest */
memcpy(circ->n_conn_id_digest, or_conn->identity_digest, DIGEST_LEN);
} else {
/* We expected a key. See if it's the right one. */
if (memcmp(or_conn->identity_digest,
circ->n_conn_id_digest, DIGEST_LEN))
continue;
}
if (!status) { /* or_conn failed; close circ */
log_info(LD_CIRC,"or_conn failed. Closing circ.");
circuit_mark_for_close(circ, END_CIRC_REASON_OR_CONN_CLOSED);
continue;
}
log_debug(LD_CIRC, "Found circ, sending create cell.");
/* circuit_deliver_create_cell will set n_circ_id and add us to
* orconn_circuid_circuit_map, so we don't need to call
* set_circid_orconn here. */
circ->n_conn = or_conn;
if (CIRCUIT_IS_ORIGIN(circ)) {
if ((err_reason =
circuit_send_next_onion_skin(TO_ORIGIN_CIRCUIT(circ))) < 0) {
log_info(LD_CIRC,
"send_next_onion_skin failed; circuit marked for closing.");
circuit_mark_for_close(circ, -err_reason);
continue;
/* XXX could this be bad, eg if next_onion_skin failed because conn
* died? */
}
} else {
/* pull the create cell out of circ->onionskin, and send it */
tor_assert(circ->n_conn_onionskin);
if (circuit_deliver_create_cell(circ,CELL_CREATE,
circ->n_conn_onionskin)<0) {
circuit_mark_for_close(circ, END_CIRC_REASON_RESOURCELIMIT);
continue;
}
tor_free(circ->n_conn_onionskin);
circuit_set_state(circ, CIRCUIT_STATE_OPEN);
}
});
smartlist_free(pending_circs);
}
/** Find a new circid that isn't currently in use on the circ->n_conn
* for the outgoing
* circuit circ, and deliver a cell of type cell_type
* (either CELL_CREATE or CELL_CREATE_FAST) with payload payload
* to this circuit.
* Return -1 if we failed to find a suitable circid, else return 0.
*/
static int
circuit_deliver_create_cell(circuit_t *circ, uint8_t cell_type,
const char *payload)
{
cell_t cell;
uint16_t id;
tor_assert(circ);
tor_assert(circ->n_conn);
tor_assert(payload);
tor_assert(cell_type == CELL_CREATE || cell_type == CELL_CREATE_FAST);
id = get_unique_circ_id_by_conn(circ->n_conn);
if (!id) {
log_warn(LD_CIRC,"failed to get unique circID.");
return -1;
}
log_debug(LD_CIRC,"Chosen circID %u.", id);
circuit_set_n_circid_orconn(circ, id, circ->n_conn);
memset(&cell, 0, sizeof(cell_t));
cell.command = cell_type;
cell.circ_id = circ->n_circ_id;
memcpy(cell.payload, payload, ONIONSKIN_CHALLENGE_LEN);
append_cell_to_circuit_queue(circ, circ->n_conn, &cell, CELL_DIRECTION_OUT);
if (CIRCUIT_IS_ORIGIN(circ)) {
/* mark it so it gets better rate limiting treatment. */
circ->n_conn->client_used = time(NULL);
}
return 0;
}
/** We've decided to start our reachability testing. If all
* is set, log this to the user. Return 1 if we did, or 0 if
* we chose not to log anything. */
int
inform_testing_reachability(void)
{
char dirbuf[128];
routerinfo_t *me = router_get_my_routerinfo();
if (!me)
return 0;
if (me->dir_port)
tor_snprintf(dirbuf, sizeof(dirbuf), " and DirPort %s:%d",
me->address, me->dir_port);
log(LOG_NOTICE, LD_OR, "Now checking whether ORPort %s:%d%s %s reachable... "
"(this may take up to %d minutes -- look for log "
"messages indicating success)",
me->address, me->or_port,
me->dir_port ? dirbuf : "",
me->dir_port ? "are" : "is",
TIMEOUT_UNTIL_UNREACHABILITY_COMPLAINT/60);
return 1;
}
/** Return true iff we should send a create_fast cell to build a circuit
* starting at router. (If router is NULL, we don't have
* information on the router, so assume true.) */
static INLINE int
should_use_create_fast_for_router(routerinfo_t *router,
origin_circuit_t *circ)
{
or_options_t *options = get_options();
if (!options->FastFirstHopPK) /* create_fast is disabled */
return 0;
if (router && router->platform &&
!tor_version_as_new_as(router->platform, "0.1.0.6-rc")) {
/* known not to work */
return 0;
}
if (server_mode(options) && circ->cpath->extend_info->onion_key) {
/* We're a server, and we know an onion key. We can choose.
* Prefer to blend in. */
return 0;
}
return 1;
}
/** This is the backbone function for building circuits.
*
* If circ's first hop is closed, then we need to build a create
* cell and send it forward.
*
* Otherwise, we need to build a relay extend cell and send it
* forward.
*
* Return -reason if we want to tear down circ, else return 0.
*/
int
circuit_send_next_onion_skin(origin_circuit_t *circ)
{
crypt_path_t *hop;
routerinfo_t *router;
char payload[2+4+DIGEST_LEN+ONIONSKIN_CHALLENGE_LEN];
char *onionskin;
size_t payload_len;
tor_assert(circ);
if (circ->cpath->state == CPATH_STATE_CLOSED) {
int fast;
uint8_t cell_type;
log_debug(LD_CIRC,"First skin; sending create cell.");
router = router_get_by_digest(circ->_base.n_conn->identity_digest);
fast = should_use_create_fast_for_router(router, circ);
if (!fast && !circ->cpath->extend_info->onion_key) {
log_warn(LD_CIRC,
"Can't send create_fast, but have no onion key. Failing.");
return - END_CIRC_REASON_INTERNAL;
}
if (!fast) {
/* We are an OR, or we are connecting to an old Tor: we should
* send an old slow create cell.
*/
cell_type = CELL_CREATE;
if (onion_skin_create(circ->cpath->extend_info->onion_key,
&(circ->cpath->dh_handshake_state),
payload) < 0) {
log_warn(LD_CIRC,"onion_skin_create (first hop) failed.");
return - END_CIRC_REASON_INTERNAL;
}
} else {
/* We are not an OR, and we're building the first hop of a circuit to a
* new OR: we can be speedy and use CREATE_FAST to save an RSA operation
* and a DH operation. */
cell_type = CELL_CREATE_FAST;
memset(payload, 0, sizeof(payload));
crypto_rand(circ->cpath->fast_handshake_state,
sizeof(circ->cpath->fast_handshake_state));
memcpy(payload, circ->cpath->fast_handshake_state,
sizeof(circ->cpath->fast_handshake_state));
}
if (circuit_deliver_create_cell(TO_CIRCUIT(circ), cell_type, payload) < 0)
return - END_CIRC_REASON_RESOURCELIMIT;
circ->cpath->state = CPATH_STATE_AWAITING_KEYS;
circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_BUILDING);
log_info(LD_CIRC,"First hop: finished sending %s cell to '%s'",
fast ? "CREATE_FAST" : "CREATE",
router ? router->nickname : "");
} else {
tor_assert(circ->cpath->state == CPATH_STATE_OPEN);
tor_assert(circ->_base.state == CIRCUIT_STATE_BUILDING);
log_debug(LD_CIRC,"starting to send subsequent skin.");
hop = onion_next_hop_in_cpath(circ->cpath);
if (!hop) {
/* done building the circuit. whew. */
circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_OPEN);
log_info(LD_CIRC,"circuit built!");
circuit_reset_failure_count(0);
if (!has_completed_circuit && !circ->build_state->onehop_tunnel) {
or_options_t *options = get_options();
has_completed_circuit=1;
/* FFFF Log a count of known routers here */
log(LOG_NOTICE, LD_GENERAL,
"Tor has successfully opened a circuit. "
"Looks like client functionality is working.");
control_event_client_status(LOG_NOTICE, "CIRCUIT_ESTABLISHED");
if (server_mode(options) && !check_whether_orport_reachable()) {
inform_testing_reachability();
consider_testing_reachability(1, 1);
}
}
circuit_rep_hist_note_result(circ);
circuit_has_opened(circ); /* do other actions as necessary */
return 0;
}
set_uint32(payload, htonl(hop->extend_info->addr));
set_uint16(payload+4, htons(hop->extend_info->port));
onionskin = payload+2+4;
memcpy(payload+2+4+ONIONSKIN_CHALLENGE_LEN,
hop->extend_info->identity_digest, DIGEST_LEN);
payload_len = 2+4+ONIONSKIN_CHALLENGE_LEN+DIGEST_LEN;
if (onion_skin_create(hop->extend_info->onion_key,
&(hop->dh_handshake_state), onionskin) < 0) {
log_warn(LD_CIRC,"onion_skin_create failed.");
return - END_CIRC_REASON_INTERNAL;
}
log_info(LD_CIRC,"Sending extend relay cell.");
/* send it to hop->prev, because it will transfer
* it to a create cell and then send to hop */
if (relay_send_command_from_edge(0, TO_CIRCUIT(circ),
RELAY_COMMAND_EXTEND,
payload, payload_len, hop->prev) < 0)
return 0; /* circuit is closed */
hop->state = CPATH_STATE_AWAITING_KEYS;
}
return 0;
}
/** Our clock just jumped by seconds_elapsed. Assume
* something has also gone wrong with our network: notify the user,
* and abandon all not-yet-used circuits. */
void
circuit_note_clock_jumped(int seconds_elapsed)
{
int severity = server_mode(get_options()) ? LOG_WARN : LOG_NOTICE;
log(severity, LD_GENERAL, "Your system clock just jumped %d seconds %s; "
"assuming established circuits no longer work.",
seconds_elapsed >=0 ? seconds_elapsed : -seconds_elapsed,
seconds_elapsed >=0 ? "forward" : "backward");
control_event_general_status(LOG_WARN, "CLOCK_JUMPED TIME=%d",
seconds_elapsed);
has_completed_circuit=0; /* so it'll log when it works again */
control_event_client_status(severity, "CIRCUIT_NOT_ESTABLISHED REASON=%s",
"CLOCK_JUMPED");
circuit_mark_all_unused_circs();
circuit_expire_all_dirty_circs();
}
/** Take the 'extend' cell, pull out addr/port plus the onion skin. Make
* sure we're connected to the next hop, and pass it the onion skin using
* a create cell. Return -1 if we want to warn and tear down the circuit,
* else return 0.
*/
int
circuit_extend(cell_t *cell, circuit_t *circ)
{
or_connection_t *n_conn;
relay_header_t rh;
char *onionskin;
char *id_digest=NULL;
if (circ->n_conn) {
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
"n_conn already set. Bug/attack. Closing.");
return -1;
}
if (!server_mode(get_options())) {
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
"Got an extend cell, but running as a client. Closing.");
return -1;
}
relay_header_unpack(&rh, cell->payload);
if (rh.length < 4+2+ONIONSKIN_CHALLENGE_LEN+DIGEST_LEN) {
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
"Wrong length %d on extend cell. Closing circuit.",
rh.length);
return -1;
}
circ->n_addr = ntohl(get_uint32(cell->payload+RELAY_HEADER_SIZE));
circ->n_port = ntohs(get_uint16(cell->payload+RELAY_HEADER_SIZE+4));
onionskin = cell->payload+RELAY_HEADER_SIZE+4+2;
id_digest = cell->payload+RELAY_HEADER_SIZE+4+2+ONIONSKIN_CHALLENGE_LEN;
n_conn = connection_or_get_by_identity_digest(id_digest);
/* If we don't have an open conn, or the conn we have is obsolete
* (i.e. old or broken) and the other side will let us make a second
* connection without dropping it immediately... */
if (!n_conn || n_conn->_base.state != OR_CONN_STATE_OPEN ||
(n_conn->_base.or_is_obsolete &&
router_digest_version_as_new_as(id_digest,"0.1.1.9-alpha-cvs"))) {
struct in_addr in;
char tmpbuf[INET_NTOA_BUF_LEN];
in.s_addr = htonl(circ->n_addr);
tor_inet_ntoa(&in,tmpbuf,sizeof(tmpbuf));
log_info(LD_CIRC|LD_OR,"Next router (%s:%d) not connected. Connecting.",
tmpbuf, circ->n_port);
circ->n_conn_onionskin = tor_malloc(ONIONSKIN_CHALLENGE_LEN);
memcpy(circ->n_conn_onionskin, onionskin, ONIONSKIN_CHALLENGE_LEN);
circuit_set_state(circ, CIRCUIT_STATE_OR_WAIT);
/* imprint the circuit with its future n_conn->id */
memcpy(circ->n_conn_id_digest, id_digest, DIGEST_LEN);
if (n_conn && !n_conn->_base.or_is_obsolete) {
circ->n_addr = n_conn->_base.addr;
circ->n_port = n_conn->_base.port;
} else {
/* we should try to open a connection */
n_conn = connection_or_connect(circ->n_addr, circ->n_port, id_digest);
if (!n_conn) {
log_info(LD_CIRC,"Launching n_conn failed. Closing circuit.");
circuit_mark_for_close(circ, END_CIRC_REASON_CONNECTFAILED);
return 0;
}
log_debug(LD_CIRC,"connecting in progress (or finished). Good.");
}
/* return success. The onion/circuit/etc will be taken care of
* automatically (may already have been) whenever n_conn reaches
* OR_CONN_STATE_OPEN.
*/
return 0;
}
/* these may be different if the router connected to us from elsewhere */
circ->n_addr = n_conn->_base.addr;
circ->n_port = n_conn->_base.port;
circ->n_conn = n_conn;
memcpy(circ->n_conn_id_digest, n_conn->identity_digest, DIGEST_LEN);
log_debug(LD_CIRC,"n_conn is %s:%u",
n_conn->_base.address,n_conn->_base.port);
if (circuit_deliver_create_cell(circ, CELL_CREATE, onionskin) < 0)
return -1;
return 0;
}
/** Initialize cpath-\>{f|b}_{crypto|digest} from the key material in
* key_data. key_data must contain CPATH_KEY_MATERIAL bytes, which are
* used as follows:
* - 20 to initialize f_digest
* - 20 to initialize b_digest
* - 16 to key f_crypto
* - 16 to key b_crypto
*
* (If 'reverse' is true, then f_XX and b_XX are swapped.)
*/
int
circuit_init_cpath_crypto(crypt_path_t *cpath, const char *key_data,
int reverse)
{
crypto_digest_env_t *tmp_digest;
crypto_cipher_env_t *tmp_crypto;
tor_assert(cpath);
tor_assert(key_data);
tor_assert(!(cpath->f_crypto || cpath->b_crypto ||
cpath->f_digest || cpath->b_digest));
cpath->f_digest = crypto_new_digest_env();
crypto_digest_add_bytes(cpath->f_digest, key_data, DIGEST_LEN);
cpath->b_digest = crypto_new_digest_env();
crypto_digest_add_bytes(cpath->b_digest, key_data+DIGEST_LEN, DIGEST_LEN);
if (!(cpath->f_crypto =
crypto_create_init_cipher(key_data+(2*DIGEST_LEN),1))) {
log_warn(LD_BUG,"Forward cipher initialization failed.");
return -1;
}
if (!(cpath->b_crypto =
crypto_create_init_cipher(key_data+(2*DIGEST_LEN)+CIPHER_KEY_LEN,0))) {
log_warn(LD_BUG,"Backward cipher initialization failed.");
return -1;
}
if (reverse) {
tmp_digest = cpath->f_digest;
cpath->f_digest = cpath->b_digest;
cpath->b_digest = tmp_digest;
tmp_crypto = cpath->f_crypto;
cpath->f_crypto = cpath->b_crypto;
cpath->b_crypto = tmp_crypto;
}
return 0;
}
/** A created or extended cell came back to us on the circuit, and it included
* reply as its body. (If reply_type is CELL_CREATED, the body
* contains (the second DH key, plus KH). If reply_type is
* CELL_CREATED_FAST, the body contains a secret y and a hash H(x|y).)
*
* Calculate the appropriate keys and digests, make sure KH is
* correct, and initialize this hop of the cpath.
*
* Return - reason if we want to mark circ for close, else return 0.
*/
int
circuit_finish_handshake(origin_circuit_t *circ, uint8_t reply_type,
const char *reply)
{
char keys[CPATH_KEY_MATERIAL_LEN];
crypt_path_t *hop;
if (circ->cpath->state == CPATH_STATE_AWAITING_KEYS)
hop = circ->cpath;
else {
hop = onion_next_hop_in_cpath(circ->cpath);
if (!hop) { /* got an extended when we're all done? */
log_warn(LD_PROTOCOL,"got extended when circ already built? Closing.");
return - END_CIRC_REASON_TORPROTOCOL;
}
}
tor_assert(hop->state == CPATH_STATE_AWAITING_KEYS);
if (reply_type == CELL_CREATED && hop->dh_handshake_state) {
if (onion_skin_client_handshake(hop->dh_handshake_state, reply, keys,
DIGEST_LEN*2+CIPHER_KEY_LEN*2) < 0) {
log_warn(LD_CIRC,"onion_skin_client_handshake failed.");
return -END_CIRC_REASON_TORPROTOCOL;
}
/* Remember hash of g^xy */
memcpy(hop->handshake_digest, reply+DH_KEY_LEN, DIGEST_LEN);
} else if (reply_type == CELL_CREATED_FAST && !hop->dh_handshake_state) {
if (fast_client_handshake(hop->fast_handshake_state, reply, keys,
DIGEST_LEN*2+CIPHER_KEY_LEN*2) < 0) {
log_warn(LD_CIRC,"fast_client_handshake failed.");
return -END_CIRC_REASON_TORPROTOCOL;
}
memcpy(hop->handshake_digest, reply+DIGEST_LEN, DIGEST_LEN);
} else {
log_warn(LD_PROTOCOL,"CREATED cell type did not match CREATE cell type.");
return -END_CIRC_REASON_TORPROTOCOL;
}
if (hop->dh_handshake_state) {
crypto_dh_free(hop->dh_handshake_state); /* don't need it anymore */
hop->dh_handshake_state = NULL;
}
memset(hop->fast_handshake_state, 0, sizeof(hop->fast_handshake_state));
if (circuit_init_cpath_crypto(hop, keys, 0)<0) {
return -END_CIRC_REASON_TORPROTOCOL;
}
hop->state = CPATH_STATE_OPEN;
log_info(LD_CIRC,"Finished building %scircuit hop:",
(reply_type == CELL_CREATED_FAST) ? "fast " : "");
circuit_log_path(LOG_INFO,LD_CIRC,circ);
control_event_circuit_status(circ, CIRC_EVENT_EXTENDED, 0);
return 0;
}
/** We received a relay truncated cell on circ.
*
* Since we don't ask for truncates currently, getting a truncated
* means that a connection broke or an extend failed. For now,
* just give up: for circ to close, and return 0.
*/
int
circuit_truncated(origin_circuit_t *circ, crypt_path_t *layer)
{
// crypt_path_t *victim;
// connection_t *stream;
tor_assert(circ);
tor_assert(layer);
/* XXX Since we don't ask for truncates currently, getting a truncated
* means that a connection broke or an extend failed. For now,
* just give up.
*/
circuit_mark_for_close(TO_CIRCUIT(circ),
END_CIRC_REASON_FLAG_REMOTE|END_CIRC_REASON_OR_CONN_CLOSED);
return 0;
#if 0
while (layer->next != circ->cpath) {
/* we need to clear out layer->next */
victim = layer->next;
log_debug(LD_CIRC, "Killing a layer of the cpath.");
for (stream = circ->p_streams; stream; stream=stream->next_stream) {
if (stream->cpath_layer == victim) {
log_info(LD_APP, "Marking stream %d for close because of truncate.",
stream->stream_id);
/* no need to send 'end' relay cells,
* because the other side's already dead
*/
connection_mark_unattached_ap(stream, END_STREAM_REASON_DESTROY);
}
}
layer->next = victim->next;
circuit_free_cpath_node(victim);
}
log_info(LD_CIRC, "finished");
return 0;
#endif
}
/** Given a response payload and keys, initialize, then send a created
* cell back.
*/
int
onionskin_answer(or_circuit_t *circ, uint8_t cell_type, const char *payload,
const char *keys)
{
cell_t cell;
crypt_path_t *tmp_cpath;
tmp_cpath = tor_malloc_zero(sizeof(crypt_path_t));
tmp_cpath->magic = CRYPT_PATH_MAGIC;
memset(&cell, 0, sizeof(cell_t));
cell.command = cell_type;
cell.circ_id = circ->p_circ_id;
circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_OPEN);
memcpy(cell.payload, payload,
cell_type == CELL_CREATED ? ONIONSKIN_REPLY_LEN : DIGEST_LEN*2);
log_debug(LD_CIRC,"init digest forward 0x%.8x, backward 0x%.8x.",
(unsigned int)*(uint32_t*)(keys),
(unsigned int)*(uint32_t*)(keys+20));
if (circuit_init_cpath_crypto(tmp_cpath, keys, 0)<0) {
log_warn(LD_BUG,"Circuit initialization failed");
tor_free(tmp_cpath);
return -1;
}
circ->n_digest = tmp_cpath->f_digest;
circ->n_crypto = tmp_cpath->f_crypto;
circ->p_digest = tmp_cpath->b_digest;
circ->p_crypto = tmp_cpath->b_crypto;
tmp_cpath->magic = 0;
tor_free(tmp_cpath);
if (cell_type == CELL_CREATED)
memcpy(circ->handshake_digest, cell.payload+DH_KEY_LEN, DIGEST_LEN);
else
memcpy(circ->handshake_digest, cell.payload+DIGEST_LEN, DIGEST_LEN);
circ->is_first_hop = (cell_type == CELL_CREATED_FAST);
append_cell_to_circuit_queue(TO_CIRCUIT(circ),
circ->p_conn, &cell, CELL_DIRECTION_IN);
log_debug(LD_CIRC,"Finished sending 'created' cell.");
if (!is_local_IP(circ->p_conn->_base.addr) &&
!connection_or_nonopen_was_started_here(circ->p_conn)) {
/* record that we could process create cells from a non-local conn
* that we didn't initiate; presumably this means that create cells
* can reach us too. */
router_orport_found_reachable();
}
return 0;
}
/** Choose a length for a circuit of purpose purpose.
* Default length is 3 + the number of endpoints that would give something
* away. If the routerlist routers doesn't have enough routers
* to handle the desired path length, return as large a path length as
* is feasible, except if it's less than 2, in which case return -1.
*/
static int
new_route_len(uint8_t purpose, extend_info_t *exit,
smartlist_t *routers)
{
int num_acceptable_routers;
int routelen;
tor_assert(routers);
#ifdef TOR_PERF
routelen = 2;
#else
routelen = 3;
if (exit &&
purpose != CIRCUIT_PURPOSE_TESTING &&
purpose != CIRCUIT_PURPOSE_S_ESTABLISH_INTRO)
routelen++;
#endif
log_debug(LD_CIRC,"Chosen route length %d (%d routers available).",
routelen, smartlist_len(routers));
num_acceptable_routers = count_acceptable_routers(routers);
if (num_acceptable_routers < 2) {
log_info(LD_CIRC,
"Not enough acceptable routers (%d). Discarding this circuit.",
num_acceptable_routers);
return -1;
}
if (num_acceptable_routers < routelen) {
log_info(LD_CIRC,"Not enough routers: cutting routelen from %d to %d.",
routelen, num_acceptable_routers);
routelen = num_acceptable_routers;
}
return routelen;
}
/** Fetch the list of predicted ports, dup it into a smartlist of
* uint16_t's, remove the ones that are already handled by an
* existing circuit, and return it.
*/
static smartlist_t *
circuit_get_unhandled_ports(time_t now)
{
smartlist_t *source = rep_hist_get_predicted_ports(now);
smartlist_t *dest = smartlist_create();
uint16_t *tmp;
int i;
for (i = 0; i < smartlist_len(source); ++i) {
tmp = tor_malloc(sizeof(uint16_t));
memcpy(tmp, smartlist_get(source, i), sizeof(uint16_t));
smartlist_add(dest, tmp);
}
circuit_remove_handled_ports(dest);
return dest;
}
/** Return 1 if we already have circuits present or on the way for
* all anticipated ports. Return 0 if we should make more.
*
* If we're returning 0, set need_uptime and need_capacity to
* indicate any requirements that the unhandled ports have.
*/
int
circuit_all_predicted_ports_handled(time_t now, int *need_uptime,
int *need_capacity)
{
int i, enough;
uint16_t *port;
smartlist_t *sl = circuit_get_unhandled_ports(now);
smartlist_t *LongLivedServices = get_options()->LongLivedPorts;
tor_assert(need_uptime);
tor_assert(need_capacity);
enough = (smartlist_len(sl) == 0);
for (i = 0; i < smartlist_len(sl); ++i) {
port = smartlist_get(sl, i);
if (smartlist_string_num_isin(LongLivedServices, *port))
*need_uptime = 1;
tor_free(port);
}
smartlist_free(sl);
return enough;
}
/** Return 1 if router can handle one or more of the ports in
* needed_ports, else return 0.
*/
static int
router_handles_some_port(routerinfo_t *router, smartlist_t *needed_ports)
{
int i;
uint16_t port;
for (i = 0; i < smartlist_len(needed_ports); ++i) {
addr_policy_result_t r;
port = *(uint16_t *)smartlist_get(needed_ports, i);
tor_assert(port);
r = compare_addr_to_addr_policy(0, port, router->exit_policy);
if (r != ADDR_POLICY_REJECTED && r != ADDR_POLICY_PROBABLY_REJECTED)
return 1;
}
return 0;
}
/** Return true iff conn needs another general circuit to be
* built. */
static int
ap_stream_wants_exit_attention(connection_t *conn)
{
if (conn->type == CONN_TYPE_AP &&
conn->state == AP_CONN_STATE_CIRCUIT_WAIT &&
!conn->marked_for_close &&
!connection_edge_is_rendezvous_stream(TO_EDGE_CONN(conn)) &&
!circuit_stream_is_being_handled(TO_EDGE_CONN(conn), 0,
MIN_CIRCUITS_HANDLING_STREAM))
return 1;
return 0;
}
/** Return a pointer to a suitable router to be the exit node for the
* general-purpose circuit we're about to build.
*
* Look through the connection array, and choose a router that maximizes
* the number of pending streams that can exit from this router.
*
* Return NULL if we can't find any suitable routers.
*/
static routerinfo_t *
choose_good_exit_server_general(routerlist_t *dir, int need_uptime,
int need_capacity)
{
int *n_supported;
int i;
int n_pending_connections = 0;
smartlist_t *connections;
int best_support = -1;
int n_best_support=0;
smartlist_t *sl, *preferredexits, *excludedexits;
routerinfo_t *router;
or_options_t *options = get_options();
connections = get_connection_array();
/* Count how many connections are waiting for a circuit to be built.
* We use this for log messages now, but in the future we may depend on it.
*/
SMARTLIST_FOREACH(connections, connection_t *, conn,
{
if (ap_stream_wants_exit_attention(conn))
++n_pending_connections;
});
// log_fn(LOG_DEBUG, "Choosing exit node; %d connections are pending",
// n_pending_connections);
/* Now we count, for each of the routers in the directory, how many
* of the pending connections could possibly exit from that
* router (n_supported[i]). (We can't be sure about cases where we
* don't know the IP address of the pending connection.)
*/
n_supported = tor_malloc(sizeof(int)*smartlist_len(dir->routers));
for (i = 0; i < smartlist_len(dir->routers); ++i) {/* iterate over routers */
router = smartlist_get(dir->routers, i);
if (router_is_me(router)) {
n_supported[i] = -1;
// log_fn(LOG_DEBUG,"Skipping node %s -- it's me.", router->nickname);
/* XXX there's probably a reverse predecessor attack here, but
* it's slow. should we take this out? -RD
*/
continue;
}
if (!router->is_running || router->is_bad_exit) {
n_supported[i] = -1;
continue; /* skip routers that are known to be down or bad exits */
}
if (router_is_unreliable(router, need_uptime, need_capacity, 0)) {
n_supported[i] = -1;
continue; /* skip routers that are not suitable */
}
if (!(router->is_valid || options->_AllowInvalid & ALLOW_INVALID_EXIT)) {
/* if it's invalid and we don't want it */
n_supported[i] = -1;
// log_fn(LOG_DEBUG,"Skipping node %s (index %d) -- invalid router.",
// router->nickname, i);
continue; /* skip invalid routers */
}
if (router_exit_policy_rejects_all(router)) {
n_supported[i] = -1;
// log_fn(LOG_DEBUG,"Skipping node %s (index %d) -- it rejects all.",
// router->nickname, i);
continue; /* skip routers that reject all */
}
n_supported[i] = 0;
/* iterate over connections */
SMARTLIST_FOREACH(connections, connection_t *, conn,
{
if (!ap_stream_wants_exit_attention(conn))
continue; /* Skip everything but APs in CIRCUIT_WAIT */
if (connection_ap_can_use_exit(TO_EDGE_CONN(conn), router)) {
++n_supported[i];
// log_fn(LOG_DEBUG,"%s is supported. n_supported[%d] now %d.",
// router->nickname, i, n_supported[i]);
} else {
// log_fn(LOG_DEBUG,"%s (index %d) would reject this stream.",
// router->nickname, i);
}
}); /* End looping over connections. */
if (n_supported[i] > best_support) {
/* If this router is better than previous ones, remember its index
* and goodness, and start counting how many routers are this good. */
best_support = n_supported[i]; n_best_support=1;
// log_fn(LOG_DEBUG,"%s is new best supported option so far.",
// router->nickname);
} else if (n_supported[i] == best_support) {
/* If this router is _as good_ as the best one, just increment the
* count of equally good routers.*/
++n_best_support;
}
}
log_info(LD_CIRC,
"Found %d servers that might support %d/%d pending connections.",
n_best_support, best_support >= 0 ? best_support : 0,
n_pending_connections);
preferredexits = smartlist_create();
add_nickname_list_to_smartlist(preferredexits,options->ExitNodes,1);
excludedexits = smartlist_create();
add_nickname_list_to_smartlist(excludedexits,options->ExcludeNodes,0);
sl = smartlist_create();
/* If any routers definitely support any pending connections, choose one
* at random. */
if (best_support > 0) {
for (i = 0; i < smartlist_len(dir->routers); i++)
if (n_supported[i] == best_support)
smartlist_add(sl, smartlist_get(dir->routers, i));
smartlist_subtract(sl,excludedexits);
if (options->StrictExitNodes || smartlist_overlap(sl,preferredexits))
smartlist_intersect(sl,preferredexits);
router = routerlist_sl_choose_by_bandwidth(sl, WEIGHT_FOR_EXIT);
} else {
/* Either there are no pending connections, or no routers even seem to
* possibly support any of them. Choose a router at random that satisfies
* at least one predicted exit port. */
int try;
smartlist_t *needed_ports;
if (best_support == -1) {
if (need_uptime || need_capacity) {
log_info(LD_CIRC,
"We couldn't find any live%s%s routers; falling back "
"to list of all routers.",
need_capacity?", fast":"",
need_uptime?", stable":"");
smartlist_free(preferredexits);
smartlist_free(excludedexits);
smartlist_free(sl);
tor_free(n_supported);
return choose_good_exit_server_general(dir, 0, 0);
}
log_notice(LD_CIRC, "All routers are down or won't exit -- choosing a "
"doomed exit at random.");
}
needed_ports = circuit_get_unhandled_ports(time(NULL));
for (try = 0; try < 2; try++) {
/* try once to pick only from routers that satisfy a needed port,
* then if there are none, pick from any that support exiting. */
for (i = 0; i < smartlist_len(dir->routers); i++) {
router = smartlist_get(dir->routers, i);
if (n_supported[i] != -1 &&
(try || router_handles_some_port(router, needed_ports))) {
// log_fn(LOG_DEBUG,"Try %d: '%s' is a possibility.",
// try, router->nickname);
smartlist_add(sl, router);
}
}
smartlist_subtract(sl,excludedexits);
if (options->StrictExitNodes || smartlist_overlap(sl,preferredexits))
smartlist_intersect(sl,preferredexits);
/* XXX sometimes the above results in null, when the requested
* exit node is down. we should pick it anyway. */
router = routerlist_sl_choose_by_bandwidth(sl, WEIGHT_FOR_EXIT);
if (router)
break;
}
SMARTLIST_FOREACH(needed_ports, uint16_t *, cp, tor_free(cp));
smartlist_free(needed_ports);
}
smartlist_free(preferredexits);
smartlist_free(excludedexits);
smartlist_free(sl);
tor_free(n_supported);
if (router) {
log_info(LD_CIRC, "Chose exit server '%s'", router->nickname);
return router;
}
if (options->StrictExitNodes) {
log_warn(LD_CIRC,
"No specified exit routers seem to be running, and "
"StrictExitNodes is set: can't choose an exit.");
}
return NULL;
}
/** Return a pointer to a suitable router to be the exit node for the
* circuit of purpose purpose that we're about to build (or NULL
* if no router is suitable).
*
* For general-purpose circuits, pass it off to
* choose_good_exit_server_general()
*
* For client-side rendezvous circuits, choose a random node, weighted
* toward the preferences in 'options'.
*/
static routerinfo_t *
choose_good_exit_server(uint8_t purpose, routerlist_t *dir,
int need_uptime, int need_capacity, int is_internal)
{
or_options_t *options = get_options();
switch (purpose) {
case CIRCUIT_PURPOSE_C_GENERAL:
if (is_internal) /* pick it like a middle hop */
return router_choose_random_node(NULL, get_options()->ExcludeNodes,
NULL, need_uptime, need_capacity, 0,
get_options()->_AllowInvalid & ALLOW_INVALID_MIDDLE, 0, 0);
else
return choose_good_exit_server_general(dir,need_uptime,need_capacity);
case CIRCUIT_PURPOSE_C_ESTABLISH_REND:
return router_choose_random_node(
options->RendNodes, options->RendExcludeNodes,
NULL, need_uptime, need_capacity, 0,
options->_AllowInvalid & ALLOW_INVALID_RENDEZVOUS, 0, 0);
}
log_warn(LD_BUG,"Unhandled purpose %d", purpose);
tor_fragile_assert();
return NULL;
}
/** Decide a suitable length for circ's cpath, and pick an exit
* router (or use exit if provided). Store these in the
* cpath. Return 0 if ok, -1 if circuit should be closed. */
static int
onion_pick_cpath_exit(origin_circuit_t *circ, extend_info_t *exit)
{
cpath_build_state_t *state = circ->build_state;
routerlist_t *rl = router_get_routerlist();
if (state->onehop_tunnel) {
log_debug(LD_CIRC, "Launching a one-hop circuit for dir tunnel.");
state->desired_path_len = 1;
} else {
int r = new_route_len(circ->_base.purpose, exit, rl->routers);
if (r < 1) /* must be at least 1 */
return -1;
state->desired_path_len = r;
}
if (exit) { /* the circuit-builder pre-requested one */
log_info(LD_CIRC,"Using requested exit node '%s'", exit->nickname);
exit = extend_info_dup(exit);
} else { /* we have to decide one */
routerinfo_t *router =
choose_good_exit_server(circ->_base.purpose, rl, state->need_uptime,
state->need_capacity, state->is_internal);
if (!router) {
log_warn(LD_CIRC,"failed to choose an exit server");
return -1;
}
exit = extend_info_from_router(router);
}
state->chosen_exit = exit;
return 0;
}
/** Give circ a new exit destination to exit, and add a
* hop to the cpath reflecting this. Don't send the next extend cell --
* the caller will do this if it wants to.
*/
int
circuit_append_new_exit(origin_circuit_t *circ, extend_info_t *exit)
{
cpath_build_state_t *state;
tor_assert(exit);
tor_assert(circ);
state = circ->build_state;
tor_assert(state);
if (state->chosen_exit)
extend_info_free(state->chosen_exit);
state->chosen_exit = extend_info_dup(exit);
++circ->build_state->desired_path_len;
onion_append_hop(&circ->cpath, exit);
return 0;
}
/** Take an open circ, and add a new hop at the end, based on
* info. Set its state back to CIRCUIT_STATE_BUILDING, and then
* send the next extend cell to begin connecting to that hop.
*/
int
circuit_extend_to_new_exit(origin_circuit_t *circ, extend_info_t *exit)
{
int err_reason = 0;
circuit_append_new_exit(circ, exit);
circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_BUILDING);
if ((err_reason = circuit_send_next_onion_skin(circ))<0) {
log_warn(LD_CIRC, "Couldn't extend circuit to new point '%s'.",
exit->nickname);
circuit_mark_for_close(TO_CIRCUIT(circ), -err_reason);
return -1;
}
return 0;
}
/** Return the number of routers in routers that are currently up
* and available for building circuits through.
*/
static int
count_acceptable_routers(smartlist_t *routers)
{
int i, n;
int num=0;
routerinfo_t *r;
n = smartlist_len(routers);
for (i=0;inickname);
if (r->is_running == 0) {
// log_debug(LD_CIRC,"Nope, the directory says %d is not running.",i);
goto next_i_loop;
}
if (r->is_valid == 0) {
// log_debug(LD_CIRC,"Nope, the directory says %d is not valid.",i);
goto next_i_loop;
/* XXX This clause makes us count incorrectly: if AllowInvalidRouters
* allows this node in some places, then we're getting an inaccurate
* count. For now, be conservative and don't count it. But later we
* should try to be smarter. */
}
num++;
// log_debug(LD_CIRC,"I like %d. num_acceptable_routers now %d.",i, num);
next_i_loop:
; /* C requires an explicit statement after the label */
}
return num;
}
/** Add new_hop to the end of the doubly-linked-list head_ptr.
* This function is used to extend cpath by another hop.
*/
void
onion_append_to_cpath(crypt_path_t **head_ptr, crypt_path_t *new_hop)
{
if (*head_ptr) {
new_hop->next = (*head_ptr);
new_hop->prev = (*head_ptr)->prev;
(*head_ptr)->prev->next = new_hop;
(*head_ptr)->prev = new_hop;
} else {
*head_ptr = new_hop;
new_hop->prev = new_hop->next = new_hop;
}
}
/** Pick a random server digest that's running a Tor version that
* doesn't have the reachability bug. These are versions 0.1.1.21-cvs+
* and 0.1.2.1-alpha+. Avoid picking authorities, since we're
* probably already connected to them.
*
* We only return one, so this doesn't become stupid when the
* whole network has upgraded.
* XXX021 we can great simplify this function now that all the broken
* versions are obsolete. -RD */
static char *
compute_preferred_testing_list(const char *answer)
{
smartlist_t *choices;
routerlist_t *rl = router_get_routerlist();
routerinfo_t *router;
char *s;
if (answer) /* they have one in mind -- easy */
return tor_strdup(answer);
choices = smartlist_create();
/* now count up our choices */
SMARTLIST_FOREACH(rl->routers, routerinfo_t *, r,
if (r->is_running && r->is_valid &&
((tor_version_as_new_as(r->platform,"0.1.1.21-cvs") &&
!tor_version_as_new_as(r->platform,"0.1.2.0-alpha-cvs")) ||
tor_version_as_new_as(r->platform,"0.1.2.1-alpha")) &&
!is_local_IP(r->addr) &&
!router_get_trusteddirserver_by_digest(r->cache_info.identity_digest))
smartlist_add(choices, r));
router = smartlist_choose(choices);
smartlist_free(choices);
if (!router) {
log_info(LD_CIRC, "Looking for middle server that doesn't have the "
"reachability bug, but didn't find one. Oh well.");
return NULL;
}
log_info(LD_CIRC, "Looking for middle server that doesn't have the "
"reachability bug, and chose '%s'. Great.", router->nickname);
s = tor_malloc(HEX_DIGEST_LEN+2);
s[0] = '$';
base16_encode(s+1, HEX_DIGEST_LEN+1,
router->cache_info.identity_digest, DIGEST_LEN);
return s;
}
/** A helper function used by onion_extend_cpath(). Use purpose
* and state and the cpath head (currently populated only
* to length cur_len to decide a suitable middle hop for a
* circuit. In particular, make sure we don't pick the exit node or its
* family, and make sure we don't duplicate any previous nodes or their
* families. */
static routerinfo_t *
choose_good_middle_server(uint8_t purpose,
cpath_build_state_t *state,
crypt_path_t *head,
int cur_len)
{
int i;
routerinfo_t *r, *choice;
crypt_path_t *cpath;
smartlist_t *excluded;
or_options_t *options = get_options();
char *preferred = NULL;
tor_assert(_CIRCUIT_PURPOSE_MIN <= purpose &&
purpose <= _CIRCUIT_PURPOSE_MAX);
log_debug(LD_CIRC, "Contemplating intermediate hop: random choice.");
excluded = smartlist_create();
if ((r = build_state_get_exit_router(state))) {
smartlist_add(excluded, r);
routerlist_add_family(excluded, r);
}
for (i = 0, cpath = head; i < cur_len; ++i, cpath=cpath->next) {
if ((r = router_get_by_digest(cpath->extend_info->identity_digest))) {
smartlist_add(excluded, r);
routerlist_add_family(excluded, r);
}
}
if (purpose == CIRCUIT_PURPOSE_TESTING)
preferred = compute_preferred_testing_list(options->TestVia);
choice = router_choose_random_node(preferred,
options->ExcludeNodes, excluded,
state->need_uptime, state->need_capacity, 0,
options->_AllowInvalid & ALLOW_INVALID_MIDDLE, 0, 0);
tor_free(preferred);
smartlist_free(excluded);
return choice;
}
/** Pick a good entry server for the circuit to be built according to
* state. Don't reuse a chosen exit (if any), don't use this
* router (if we're an OR), and respect firewall settings; if we're
* configured to use entry guards, return one.
*
* If state is NULL, we're choosing a router to serve as an entry
* guard, not for any particular circuit.
*/
static routerinfo_t *
choose_good_entry_server(uint8_t purpose, cpath_build_state_t *state)
{
routerinfo_t *r, *choice;
smartlist_t *excluded;
or_options_t *options = get_options();
(void)purpose; /* not used yet. */
if (state && options->UseEntryGuards) {
return choose_random_entry(state);
}
excluded = smartlist_create();
if (state && (r = build_state_get_exit_router(state))) {
smartlist_add(excluded, r);
routerlist_add_family(excluded, r);
}
if (firewall_is_fascist_or()) {
/* exclude all ORs that listen on the wrong port */
routerlist_t *rl = router_get_routerlist();
int i;
for (i=0; i < smartlist_len(rl->routers); i++) {
r = smartlist_get(rl->routers, i);
if (!fascist_firewall_allows_address_or(r->addr,r->or_port))
smartlist_add(excluded, r);
}
}
/* and exclude current entry guards, if applicable */
if (options->UseEntryGuards && entry_guards) {
SMARTLIST_FOREACH(entry_guards, entry_guard_t *, entry,
{
if ((r = router_get_by_digest(entry->identity)))
smartlist_add(excluded, r);
});
}
choice = router_choose_random_node(
NULL, options->ExcludeNodes,
excluded, state ? state->need_uptime : 0,
state ? state->need_capacity : 0,
state ? 0 : 1,
options->_AllowInvalid & ALLOW_INVALID_ENTRY, 0, 0);
smartlist_free(excluded);
return choice;
}
/** Return the first non-open hop in cpath, or return NULL if all
* hops are open. */
static crypt_path_t *
onion_next_hop_in_cpath(crypt_path_t *cpath)
{
crypt_path_t *hop = cpath;
do {
if (hop->state != CPATH_STATE_OPEN)
return hop;
hop = hop->next;
} while (hop != cpath);
return NULL;
}
/** Choose a suitable next hop in the cpath head_ptr,
* based on state. Append the hop info to head_ptr.
*/
static int
onion_extend_cpath(origin_circuit_t *circ)
{
uint8_t purpose = circ->_base.purpose;
cpath_build_state_t *state = circ->build_state;
int cur_len = circuit_get_cpath_len(circ);
extend_info_t *info = NULL;
if (cur_len >= state->desired_path_len) {
log_debug(LD_CIRC, "Path is complete: %d steps long",
state->desired_path_len);
return 1;
}
log_debug(LD_CIRC, "Path is %d long; we want %d", cur_len,
state->desired_path_len);
if (cur_len == state->desired_path_len - 1) { /* Picking last node */
info = extend_info_dup(state->chosen_exit);
} else if (cur_len == 0) { /* picking first node */
routerinfo_t *r = choose_good_entry_server(purpose, state);
if (r)
info = extend_info_from_router(r);
} else {
routerinfo_t *r =
choose_good_middle_server(purpose, state, circ->cpath, cur_len);
if (r)
info = extend_info_from_router(r);
}
if (!info) {
log_warn(LD_CIRC,"Failed to find node for hop %d of our path. Discarding "
"this circuit.", cur_len);
return -1;
}
log_debug(LD_CIRC,"Chose router %s for hop %d (exit is %s)",
info->nickname, cur_len+1, build_state_get_exit_nickname(state));
onion_append_hop(&circ->cpath, info);
extend_info_free(info);
return 0;
}
/** Create a new hop, annotate it with information about its
* corresponding router choice, and append it to the
* end of the cpath head_ptr. */
static int
onion_append_hop(crypt_path_t **head_ptr, extend_info_t *choice)
{
crypt_path_t *hop = tor_malloc_zero(sizeof(crypt_path_t));
/* link hop into the cpath, at the end. */
onion_append_to_cpath(head_ptr, hop);
hop->magic = CRYPT_PATH_MAGIC;
hop->state = CPATH_STATE_CLOSED;
hop->extend_info = extend_info_dup(choice);
hop->package_window = CIRCWINDOW_START;
hop->deliver_window = CIRCWINDOW_START;
return 0;
}
/** Allocate a new extend_info object based on the various arguments. */
extend_info_t *
extend_info_alloc(const char *nickname, const char *digest,
crypto_pk_env_t *onion_key,
uint32_t addr, uint16_t port)
{
extend_info_t *info = tor_malloc_zero(sizeof(extend_info_t));
memcpy(info->identity_digest, digest, DIGEST_LEN);
if (nickname)
strlcpy(info->nickname, nickname, sizeof(info->nickname));
if (onion_key)
info->onion_key = crypto_pk_dup_key(onion_key);
info->addr = addr;
info->port = port;
return info;
}
/** Allocate and return a new extend_info_t that can be used to build a
* circuit to or through the router r. */
extend_info_t *
extend_info_from_router(routerinfo_t *r)
{
tor_assert(r);
return extend_info_alloc(r->nickname, r->cache_info.identity_digest,
r->onion_pkey, r->addr, r->or_port);
}
/** Release storage held by an extend_info_t struct. */
void
extend_info_free(extend_info_t *info)
{
tor_assert(info);
if (info->onion_key)
crypto_free_pk_env(info->onion_key);
tor_free(info);
}
/** Allocate and return a new extend_info_t with the same contents as
* info. */
extend_info_t *
extend_info_dup(extend_info_t *info)
{
extend_info_t *newinfo;
tor_assert(info);
newinfo = tor_malloc(sizeof(extend_info_t));
memcpy(newinfo, info, sizeof(extend_info_t));
if (info->onion_key)
newinfo->onion_key = crypto_pk_dup_key(info->onion_key);
else
newinfo->onion_key = NULL;
return newinfo;
}
/** Return the routerinfo_t for the chosen exit router in state.
* If there is no chosen exit, or if we don't know the routerinfo_t for
* the chosen exit, return NULL.
*/
routerinfo_t *
build_state_get_exit_router(cpath_build_state_t *state)
{
if (!state || !state->chosen_exit)
return NULL;
return router_get_by_digest(state->chosen_exit->identity_digest);
}
/** Return the nickname for the chosen exit router in state. If
* there is no chosen exit, or if we don't know the routerinfo_t for the
* chosen exit, return NULL.
*/
const char *
build_state_get_exit_nickname(cpath_build_state_t *state)
{
if (!state || !state->chosen_exit)
return NULL;
return state->chosen_exit->nickname;
}
/** 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, routerinfo_t *ri,
time_t now, or_options_t *options, const char **reason)
{
char buf[HEX_DIGEST_LEN+1];
int changed = 0;
tor_assert(options);
*reason = NULL;
/* Do we want to mark this guard as bad? */
if (!ri)
*reason = "unlisted";
else if (!ri->is_running)
*reason = "down";
else if (options->UseBridges && ri->purpose != ROUTER_PURPOSE_BRIDGE)
*reason = "not a bridge";
else if (!options->UseBridges && !ri->is_possible_guard &&
!router_nickname_is_in_list(ri, options->EntryNodes))
*reason = "not recommended as a guard";
else if (router_nickname_is_in_list(ri, options->ExcludeNodes))
*reason = "excluded";
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;
}
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(entry_guard_t *e, time_t now)
{
long diff;
if (e->last_attempted < e->unreachable_since)
return 1;
diff = now - e->unreachable_since;
if (diff < 6*60*60)
return now > (e->last_attempted + 60*60);
else if (diff < 3*24*60*60)
return now > (e->last_attempted + 4*60*60);
else if (diff < 7*24*60*60)
return now > (e->last_attempted + 18*60*60);
else
return now > (e->last_attempted + 36*60*60);
}
/** Return the router 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 concensus,
* if demanded by need_uptime or need_capacity;
* (This check is currently redundant with the Guard flag, but in
* the future that might change. Best to leave it in for now.)
* - Allowed by our current ReachableORAddresses config option; and
* - Currently thought to be reachable by us (unless assume_reachable
* is true).
*/
static INLINE routerinfo_t *
entry_is_live(entry_guard_t *e, int need_uptime, int need_capacity,
int assume_reachable)
{
routerinfo_t *r;
if (e->bad_since)
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)))
return NULL;
r = router_get_by_digest(e->identity);
if (!r)
return NULL;
if (get_options()->UseBridges && r->purpose != ROUTER_PURPOSE_BRIDGE)
return NULL;
if (!get_options()->UseBridges && r->purpose != ROUTER_PURPOSE_GENERAL)
return NULL;
if (router_is_unreliable(r, need_uptime, need_capacity, 0))
return NULL;
if (!fascist_firewall_allows_address_or(r->addr,r->or_port))
return NULL;
return r;
}
/** Return the number of entry guards that we think are usable. */
static int
num_live_entry_guards(void)
{
int n = 0;
if (! entry_guards)
return 0;
SMARTLIST_FOREACH(entry_guards, entry_guard_t *, entry,
{
if (entry_is_live(entry, 0, 1, 0))
++n;
});
return n;
}
/** If digest matches the identity of any node in the
* entry_guards list, return that node. Else return NULL. */
static INLINE entry_guard_t *
is_an_entry_guard(const char *digest)
{
SMARTLIST_FOREACH(entry_guards, entry_guard_t *, entry,
if (!memcmp(digest, entry->identity, DIGEST_LEN))
return entry;
);
return NULL;
}
/** Dump a description of our list of entry guards to the log at level
* severity. */
static void
log_entry_guards(int severity)
{
smartlist_t *elements = smartlist_create();
char buf[1024];
char *s;
SMARTLIST_FOREACH(entry_guards, entry_guard_t *, e,
{
tor_snprintf(buf, sizeof(buf), "%s (%s%s)",
e->nickname,
e->bad_since ? "down " : "up ",
e->made_contact ? "made-contact" : "never-contacted");
smartlist_add(elements, tor_strdup(buf));
});
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
* useable 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;
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)) {
if (n++ == options->NumEntryGuards) {
control_event_guard(entry->nickname, entry->identity, "DEFERRED");
return;
}
}
});
#endif
}
/** Add a new (preferably stable and fast) router to our
* entry_guards list. 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 routerinfo_t *
add_an_entry_guard(routerinfo_t *chosen, int reset_status)
{
routerinfo_t *router;
entry_guard_t *entry;
if (chosen) {
router = chosen;
entry = is_an_entry_guard(router->cache_info.identity_digest);
if (entry) {
if (reset_status) {
entry->bad_since = 0;
entry->can_retry = 1;
}
return NULL;
}
} else {
router = choose_good_entry_server(CIRCUIT_PURPOSE_C_GENERAL, NULL);
if (!router)
return NULL;
}
entry = tor_malloc_zero(sizeof(entry_guard_t));
log_info(LD_CIRC, "Chose '%s' as new entry guard.", router->nickname);
strlcpy(entry->nickname, router->nickname, sizeof(entry->nickname));
memcpy(entry->identity, router->cache_info.identity_digest, DIGEST_LEN);
entry->chosen_on_date = start_of_month(time(NULL));
entry->chosen_by_version = tor_strdup(VERSION);
if (chosen) /* prepend */
smartlist_insert(entry_guards, 0, entry);
else /* append */
smartlist_add(entry_guards, entry);
control_event_guard(entry->nickname, entry->identity, "NEW");
control_event_guard_deferred();
log_entry_guards(LOG_INFO);
return router;
}
/** If the use of entry guards is configured, choose more entry guards
* until we have enough in the list. */
static void
pick_entry_guards(void)
{
or_options_t *options = get_options();
int changed = 0;
tor_assert(entry_guards);
while (num_live_entry_guards() < options->NumEntryGuards) {
if (!add_an_entry_guard(NULL, 0))
break;
changed = 1;
}
if (changed)
entry_guards_changed();
}
/** 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)
{
tor_assert(e);
tor_free(e->chosen_by_version);
tor_free(e);
}
/** Remove 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. */
static int
remove_obsolete_entry_guards(void)
{
int changed = 0, i;
for (i = 0; i < smartlist_len(entry_guards); ++i) {
entry_guard_t *entry = smartlist_get(entry_guards, i);
const char *ver = entry->chosen_by_version;
const char *msg = NULL;
tor_version_t v;
int version_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;
} else if ((tor_version_as_new_as(ver, "0.1.0.10-alpha") &&
!tor_version_as_new_as(ver, "0.1.2.16-dev")) ||
(tor_version_as_new_as(ver, "0.2.0.0-alpha") &&
!tor_version_as_new_as(ver, "0.2.0.6-alpha"))) {
msg = "was selected without regard for guard bandwidth";
version_is_bad = 1;
}
if (version_is_bad) {
char dbuf[HEX_DIGEST_LEN+1];
tor_assert(msg);
base16_encode(dbuf, sizeof(dbuf), entry->identity, DIGEST_LEN);
log_notice(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(entry_guards, i--);
log_entry_guards(LOG_INFO);
changed = 1;
}
}
return changed ? 1 : 0;
}
/** Remove all entry guards 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(void)
{
char dbuf[HEX_DIGEST_LEN+1];
char tbuf[ISO_TIME_LEN+1];
time_t now = time(NULL);
int i;
int changed = 0;
for (i = 0; i < smartlist_len(entry_guards); ) {
entry_guard_t *entry = smartlist_get(entry_guards, i);
if (entry->bad_since &&
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(entry_guards, i);
log_entry_guards(LOG_INFO);
changed = 1;
} else
++i;
}
return changed ? 1 : 0;
}
/** 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(void)
{
time_t now;
int changed = 0;
int severity = LOG_INFO;
or_options_t *options;
if (! entry_guards)
return;
options = get_options();
now = time(NULL);
SMARTLIST_FOREACH(entry_guards, entry_guard_t *, entry,
{
routerinfo_t *r = router_get_by_digest(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);
log_info(LD_CIRC, "Summary: Entry '%s' is %s, %s%s, and %s.",
entry->nickname,
entry->unreachable_since ? "unreachable" : "reachable",
entry->bad_since ? "unusable: " : "usable",
entry->bad_since ? reason : "",
entry_is_live(entry, 0, 1, 0) ? "live" : "not live");
});
if (remove_dead_entry_guards())
changed = 1;
if (changed) {
log_fn(severity, LD_CIRC, " (%d/%d entry guards are usable/new)",
num_live_entry_guards(), smartlist_len(entry_guards));
log_entry_guards(LOG_INFO);
entry_guards_changed();
}
}
/** 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.
*/
int
entry_guard_register_connect_status(const char *digest, int succeeded,
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 (! entry_guards)
return 0;
SMARTLIST_FOREACH(entry_guards, entry_guard_t *, e,
{
if (!memcmp(e->identity, digest, DIGEST_LEN)) {
entry = e;
idx = e_sl_idx;
break;
}
});
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()-1, smartlist_len(entry_guards)-1);
entry_guard_free(entry);
smartlist_del_keeporder(entry_guards, idx);
log_entry_guards(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 (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(entry_guards, entry_guard_t *, e, {
if (e == entry)
break;
if (e->made_contact) {
routerinfo_t *r = entry_is_live(e, 0, 1, 1);
if (r && e->unreachable_since) {
refuse_conn = 1;
e->can_retry = 1;
}
}
});
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(), smartlist_len(entry_guards));
log_entry_guards(LOG_INFO);
changed = 1;
}
}
if (changed)
entry_guards_changed();
return refuse_conn ? -1 : 0;
}
/** When we try to choose an entry guard, should we parse and add
* config's EntryNodes first? */
static int should_add_entry_nodes = 0;
/** Called when the value of EntryNodes changes in our configuration. */
void
entry_nodes_should_be_added(void)
{
log_info(LD_CIRC, "New EntryNodes config option detected. Will use.");
should_add_entry_nodes = 1;
}
/** Add all nodes in EntryNodes that aren't currently guard nodes to the list
* of guard nodes, at the front. */
static void
entry_guards_prepend_from_config(void)
{
or_options_t *options = get_options();
smartlist_t *entry_routers, *entry_fps;
smartlist_t *old_entry_guards_on_list, *old_entry_guards_not_on_list;
tor_assert(entry_guards);
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;
}
log_info(LD_CIRC,"Adding configured EntryNodes '%s'.",
options->EntryNodes);
entry_routers = smartlist_create();
entry_fps = smartlist_create();
old_entry_guards_on_list = smartlist_create();
old_entry_guards_not_on_list = smartlist_create();
/* Split entry guards into those on the list and those not. */
add_nickname_list_to_smartlist(entry_routers, options->EntryNodes, 0);
SMARTLIST_FOREACH(entry_routers, routerinfo_t *, ri,
smartlist_add(entry_fps,ri->cache_info.identity_digest));
SMARTLIST_FOREACH(entry_guards, entry_guard_t *, e, {
if (smartlist_digest_isin(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 entry guards from entry_routers. */
SMARTLIST_FOREACH(entry_routers, routerinfo_t *, ri, {
if (is_an_entry_guard(ri->cache_info.identity_digest)) {
SMARTLIST_DEL_CURRENT(entry_routers, ri);
}
});
/* Now build the new entry_guards list. */
smartlist_clear(entry_guards);
/* First, the previously configured guards that are in EntryNodes. */
smartlist_add_all(entry_guards, old_entry_guards_on_list);
/* Next, the rest of EntryNodes */
SMARTLIST_FOREACH(entry_routers, routerinfo_t *, ri, {
add_an_entry_guard(ri, 0);
});
/* Finally, the remaining EntryNodes, unless we're strict */
if (options->StrictEntryNodes) {
SMARTLIST_FOREACH(old_entry_guards_not_on_list, entry_guard_t *, e,
entry_guard_free(e));
} else {
smartlist_add_all(entry_guards, old_entry_guards_not_on_list);
}
smartlist_free(entry_routers);
smartlist_free(entry_fps);
smartlist_free(old_entry_guards_on_list);
smartlist_free(old_entry_guards_not_on_list);
entry_guards_changed();
}
/** Return 1 if we're fine adding arbitrary routers out of the
* directory to our entry guard list. Else return 0. */
int
entry_list_can_grow(or_options_t *options)
{
if (options->StrictEntryNodes)
return 0;
if (options->UseBridges)
return 0;
return 1;
}
/** 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). */
routerinfo_t *
choose_random_entry(cpath_build_state_t *state)
{
or_options_t *options = get_options();
smartlist_t *live_entry_guards = smartlist_create();
smartlist_t *exit_family = smartlist_create();
routerinfo_t *chosen_exit = state?build_state_get_exit_router(state) : NULL;
routerinfo_t *r = NULL;
int need_uptime = state ? state->need_uptime : 0;
int need_capacity = state ? state->need_capacity : 0;
int consider_exit_family = 0;
if (chosen_exit) {
smartlist_add(exit_family, chosen_exit);
routerlist_add_family(exit_family, chosen_exit);
consider_exit_family = 1;
}
if (!entry_guards)
entry_guards = smartlist_create();
if (should_add_entry_nodes)
entry_guards_prepend_from_config();
if (entry_list_can_grow(options) &&
(! entry_guards ||
smartlist_len(entry_guards) < options->NumEntryGuards))
pick_entry_guards();
retry:
smartlist_clear(live_entry_guards);
SMARTLIST_FOREACH(entry_guards, entry_guard_t *, entry,
{
r = entry_is_live(entry, need_uptime, need_capacity, 0);
if (r && (!consider_exit_family || !smartlist_isin(exit_family, r))) {
smartlist_add(live_entry_guards, r);
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. */
goto choose_and_finish;
}
if (smartlist_len(live_entry_guards) >= options->NumEntryGuards)
break; /* we have enough */
}
});
/* 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 him.
* (We might get 2 live-but-crummy entry guards, but so be it.) */
if (smartlist_len(live_entry_guards) < 2) {
if (entry_list_can_grow(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 */
r = add_an_entry_guard(NULL, 0);
if (r) {
smartlist_add(live_entry_guards, r);
entry_guards_changed();
}
}
if (!r && need_uptime) {
need_uptime = 0; /* try without that requirement */
goto retry;
}
if (!r && need_capacity) {
/* still no? last attempt, try without requiring capacity */
need_capacity = 0;
goto retry;
}
if (!r && !entry_list_can_grow(options) && consider_exit_family) {
/* still no? if we're using bridges or have strictentrynodes
* set, and our chosen exit is in the same family as all our
* bridges/entry guards, then be flexible about families. */
consider_exit_family = 0;
goto retry;
}
/* live_entry_guards may be empty below. Oh well, we tried. */
}
choose_and_finish:
if (entry_list_can_grow(options)) {
/* 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. */
r = smartlist_choose(live_entry_guards);
} else {
/* We need to weight by bandwidth, because our bridges or entryguards
* were not already selected proportional to their bandwidth. */
r = routerlist_sl_choose_by_bandwidth(live_entry_guards, WEIGHT_FOR_GUARD);
}
smartlist_free(live_entry_guards);
smartlist_free(exit_family);
return r;
}
/** Helper: Return the start of the month containing time. */
static time_t
start_of_month(time_t now)
{
struct tm tm;
tor_gmtime_r(&now, &tm);
tm.tm_sec = 0;
tm.tm_min = 0;
tm.tm_hour = 0;
tm.tm_mday = 1;
return tor_timegm(&tm);
}
/** Parse state and learn about the entry guards it describes.
* If set is true, and there are no errors, replace the global
* entry_list with what we find.
* On success, return 0. On failure, alloc into *msg a string
* describing the error, and return -1.
*/
int
entry_guards_parse_state(or_state_t *state, int set, char **msg)
{
entry_guard_t *node = NULL;
smartlist_t *new_entry_guards = smartlist_create();
config_line_t *line;
time_t now = time(NULL);
const char *state_version = state->TorVersion;
digestmap_t *added_by = digestmap_new();
*msg = NULL;
for (line = state->EntryGuards; line; line = line->next) {
if (!strcasecmp(line->key, "EntryGuard")) {
smartlist_t *args = smartlist_create();
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)))<0) {
*msg = tor_strdup("Unable to parse entry nodes: "
"Bad hex digest for EntryGuard");
}
}
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) {
*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)<0 ||
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 {
log_warn(LD_BUG, "Unexpected key %s", line->key);
}
}
SMARTLIST_FOREACH(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_by_version = tor_strdup(state_version);
e->chosen_on_date = start_of_month(time(NULL));
}
}
});
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 (entry_guards) {
SMARTLIST_FOREACH(entry_guards, entry_guard_t *, e,
entry_guard_free(e));
smartlist_free(entry_guards);
}
entry_guards = new_entry_guards;
entry_guards_dirty = 0;
if (remove_obsolete_entry_guards())
entry_guards_dirty = 1;
}
digestmap_free(added_by, _tor_free);
return *msg ? -1 : 0;
}
/** Our list of entry guards has changed, or some element of one
* of our entry guards has changed. Write the changes to disk within
* the next few minutes.
*/
static void
entry_guards_changed(void)
{
time_t when;
entry_guards_dirty = 1;
/* or_state_save() will call entry_guards_update_state(). */
when = get_options()->AvoidDiskWrites ? time(NULL) + 3600 : time(NULL)+600;
or_state_mark_dirty(get_or_state(), when);
}
/** If the entry guard info has not changed, do nothing and return.
* Otherwise, free the EntryGuards piece of state and create
* a new one out of the global entry_guards list, and then mark
* state dirty so it will get saved to disk.
*/
void
entry_guards_update_state(or_state_t *state)
{
config_line_t **next, *line;
if (! entry_guards_dirty)
return;
config_free_lines(state->EntryGuards);
next = &state->EntryGuards;
*next = NULL;
if (!entry_guards)
entry_guards = smartlist_create();
SMARTLIST_FOREACH(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");
line->value = tor_malloc(HEX_DIGEST_LEN+MAX_NICKNAME_LEN+2);
base16_encode(dbuf, sizeof(dbuf), e->identity, DIGEST_LEN);
tor_snprintf(line->value,HEX_DIGEST_LEN+MAX_NICKNAME_LEN+2,
"%s %s", e->nickname, dbuf);
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];
size_t val_len;
*next = line = tor_malloc_zero(sizeof(config_line_t));
line->key = tor_strdup("EntryGuardAddedBy");
val_len = (HEX_DIGEST_LEN+1+strlen(e->chosen_by_version)
+1+ISO_TIME_LEN+1);
line->value = tor_malloc(val_len);
base16_encode(d, sizeof(d), e->identity, DIGEST_LEN);
format_iso_time(t, e->chosen_on_date);
tor_snprintf(line->value, val_len, "%s %s %s",
d, e->chosen_by_version, t);
next = &(line->next);
}
});
if (!get_options()->AvoidDiskWrites)
or_state_mark_dirty(get_or_state(), 0);
entry_guards_dirty = 0;
}
/** If question is the string "entry-guards", then dump
* to *answer a newly allocated string describing all of
* the nodes in the global entry_guards list. See control-spec.txt
* for details.
* For backward compatibility, we also handle the string "helper-nodes".
* */
int
getinfo_helper_entry_guards(control_connection_t *conn,
const char *question, char **answer)
{
int use_long_names = conn->use_long_names;
if (!strcmp(question,"entry-guards") ||
!strcmp(question,"helper-nodes")) {
smartlist_t *sl = smartlist_create();
char tbuf[ISO_TIME_LEN+1];
char nbuf[MAX_VERBOSE_NICKNAME_LEN+1];
if (!entry_guards)
entry_guards = smartlist_create();
SMARTLIST_FOREACH(entry_guards, entry_guard_t *, e,
{
size_t len = MAX_VERBOSE_NICKNAME_LEN+ISO_TIME_LEN+32;
char *c = tor_malloc(len);
const char *status = NULL;
time_t when = 0;
if (!e->made_contact) {
status = "never-connected";
} else if (e->bad_since) {
when = e->bad_since;
status = "unusable";
} else {
status = "up";
}
if (use_long_names) {
routerinfo_t *ri = router_get_by_digest(e->identity);
if (ri) {
router_get_verbose_nickname(nbuf, ri);
} 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. */
}
} else {
base16_encode(nbuf, sizeof(nbuf), e->identity, DIGEST_LEN);
}
if (when) {
format_iso_time(tbuf, when);
tor_snprintf(c, len, "%s %s %s\n", nbuf, status, tbuf);
} else {
tor_snprintf(c, len, "%s %s\n", nbuf, status);
}
smartlist_add(sl, c);
});
*answer = smartlist_join_strings(sl, "", 0, NULL);
SMARTLIST_FOREACH(sl, char *, c, tor_free(c));
smartlist_free(sl);
}
return 0;
}
/** Information about a configured bridge. Currently this just matches the
* ones in the torrc file, but one day we may be able to learn about new
* bridges on our own, and remember them in the state file. */
typedef struct {
/** IPv4 address of the bridge. */
uint32_t addr;
/** TLS port for the bridge. */
uint16_t port;
/** Expected identity digest, or all \0's if we don't know what the
* digest should be. */
char identity[DIGEST_LEN];
/** When should we next try to fetch a descriptor for this bridge? */
download_status_t fetch_status;
} bridge_info_t;
/** A list of configured bridges. Whenever we actually get a descriptor
* for one, we add it as an entry guard. */
static smartlist_t *bridge_list = NULL;
/** Initialize the bridge list to empty, creating it if needed. */
void
clear_bridge_list(void)
{
if (!bridge_list)
bridge_list = smartlist_create();
SMARTLIST_FOREACH(bridge_list, bridge_info_t *, b, tor_free(b));
smartlist_clear(bridge_list);
}
/** Return a bridge pointer if ri is one of our known bridges
* (either by comparing keys if possible, else by comparing addr/port).
* Else return NULL. */
static bridge_info_t *
routerinfo_get_configured_bridge(routerinfo_t *ri)
{
if (!bridge_list)
return NULL;
SMARTLIST_FOREACH(bridge_list, bridge_info_t *, bridge,
{
if (tor_digest_is_zero(bridge->identity) &&
bridge->addr == ri->addr && bridge->port == ri->or_port)
return bridge;
if (!memcmp(bridge->identity, ri->cache_info.identity_digest,
DIGEST_LEN))
return bridge;
});
return NULL;
}
/** Return 1 if ri is one of our known bridges, else 0. */
int
routerinfo_is_a_configured_bridge(routerinfo_t *ri)
{
return routerinfo_get_configured_bridge(ri) ? 1 : 0;
}
/** Remember a new bridge at addr:port. If digest
* is set, it tells us the identity key too. */
void
bridge_add_from_config(uint32_t addr, uint16_t port, char *digest)
{
bridge_info_t *b = tor_malloc_zero(sizeof(bridge_info_t));
b->addr = addr;
b->port = port;
if (digest)
memcpy(b->identity, digest, DIGEST_LEN);
if (!bridge_list)
bridge_list = smartlist_create();
smartlist_add(bridge_list, b);
}
/** Schedule the next fetch for bridge, based on
* some retry schedule. */
static void
bridge_fetch_status_increment(bridge_info_t *bridge, time_t now)
{
switch (bridge->fetch_status.n_download_failures) {
case 0: bridge->fetch_status.next_attempt_at = now+60*15; break;
case 1: bridge->fetch_status.next_attempt_at = now+60*15; break;
default: bridge->fetch_status.next_attempt_at = now+60*60; break;
}
if (bridge->fetch_status.n_download_failures < 10)
bridge->fetch_status.n_download_failures++;
}
/** We just got a new descriptor for bridge. Reschedule the
* next fetch for a long time from now. */
static void
bridge_fetch_status_arrived(bridge_info_t *bridge, time_t now)
{
tor_assert(bridge);
bridge->fetch_status.next_attempt_at = now+60*60;
bridge->fetch_status.n_download_failures = 0;
}
/** If digest is one of our known bridges, return it. */
static bridge_info_t *
find_bridge_by_digest(char *digest)
{
SMARTLIST_FOREACH(bridge_list, bridge_info_t *, bridge,
{
if (!memcmp(bridge->identity, digest, DIGEST_LEN))
return bridge;
});
return NULL;
}
/** We need to ask bridge for its server descriptor. address
* is a helpful string describing this bridge. */
static void
launch_direct_bridge_descriptor_fetch(char *address, bridge_info_t *bridge)
{
if (connection_get_by_type_addr_port_purpose(
CONN_TYPE_DIR, bridge->addr, bridge->port,
DIR_PURPOSE_FETCH_SERVERDESC))
return; /* it's already on the way */
directory_initiate_command(address, bridge->addr,
bridge->port, 0,
1, bridge->identity,
DIR_PURPOSE_FETCH_SERVERDESC,
ROUTER_PURPOSE_BRIDGE,
0, "authority.z", NULL, 0, 0);
}
/** Fetching the bridge descriptor from the bridge authority returned a
* "not found". Fall back to trying a direct fetch. */
void
retry_bridge_descriptor_fetch_directly(char *digest)
{
bridge_info_t *bridge = find_bridge_by_digest(digest);
char address_buf[INET_NTOA_BUF_LEN+1];
struct in_addr in;
if (!bridge)
return; /* not found? oh well. */
in.s_addr = htonl(bridge->addr);
tor_inet_ntoa(&in, address_buf, sizeof(address_buf));
launch_direct_bridge_descriptor_fetch(address_buf, bridge);
}
/** For each bridge in our list for which we don't currently have a
* descriptor, fetch a new copy of its descriptor -- either directly
* from the bridge or via a bridge authority. */
void
fetch_bridge_descriptors(time_t now)
{
char address_buf[INET_NTOA_BUF_LEN+1];
struct in_addr in;
or_options_t *options = get_options();
int num_bridge_auths = get_n_authorities(BRIDGE_AUTHORITY);
int ask_bridge_directly;
int can_use_bridge_authority;
if (!bridge_list)
return;
SMARTLIST_FOREACH(bridge_list, bridge_info_t *, bridge,
{
if (bridge->fetch_status.next_attempt_at > now)
continue; /* don't bother, no need to retry yet */
/* schedule another fetch as if this one will fail, in case it does */
bridge_fetch_status_increment(bridge, now);
in.s_addr = htonl(bridge->addr);
tor_inet_ntoa(&in, address_buf, sizeof(address_buf));
can_use_bridge_authority = !tor_digest_is_zero(bridge->identity) &&
num_bridge_auths;
ask_bridge_directly = !can_use_bridge_authority ||
!options->UpdateBridgesFromAuthority;
log_debug(LD_DIR, "ask_bridge_directly=%d (%d, %d, %d)",
ask_bridge_directly, tor_digest_is_zero(bridge->identity),
!options->UpdateBridgesFromAuthority, !num_bridge_auths);
if (ask_bridge_directly &&
!fascist_firewall_allows_address_or(bridge->addr, bridge->port)) {
log_notice(LD_DIR, "Bridge at '%s:%d' isn't reachable by our "
"firewall policy. %s.", address_buf, bridge->port,
can_use_bridge_authority ?
"Asking bridge authority instead" : "Skipping");
if (can_use_bridge_authority)
ask_bridge_directly = 0;
else
continue;
}
if (ask_bridge_directly) {
/* we need to ask the bridge itself for its descriptor. */
launch_direct_bridge_descriptor_fetch(address_buf, bridge);
} else {
/* We have a digest and we want to ask an authority. We could
* combine all the requests into one, but that may give more
* hints to the bridge authority than we want to give. */
char resource[10 + HEX_DIGEST_LEN];
memcpy(resource, "fp/", 3);
base16_encode(resource+3, HEX_DIGEST_LEN+1,
bridge->identity, DIGEST_LEN);
memcpy(resource+3+HEX_DIGEST_LEN, ".z", 3);
log_info(LD_DIR, "Fetching bridge info '%s' from bridge authority.",
resource);
directory_get_from_dirserver(DIR_PURPOSE_FETCH_SERVERDESC,
ROUTER_PURPOSE_BRIDGE, resource, 0);
}
});
}
/** We just learned a descriptor for a bridge. See if that
* digest is in our entry guard list, and add it if not. */
void
learned_bridge_descriptor(routerinfo_t *ri, int from_cache)
{
tor_assert(ri);
tor_assert(ri->purpose == ROUTER_PURPOSE_BRIDGE);
if (get_options()->UseBridges) {
int first = !any_bridge_descriptors_known();
bridge_info_t *bridge = routerinfo_get_configured_bridge(ri);
time_t now = time(NULL);
ri->is_running = 1;
if (bridge) { /* if we actually want to use this one */
/* it's here; schedule its re-fetch for a long time from now. */
if (!from_cache)
bridge_fetch_status_arrived(bridge, now);
add_an_entry_guard(ri, 1);
log_notice(LD_DIR, "new bridge descriptor '%s' (%s)", ri->nickname,
from_cache ? "cached" : "fresh");
if (first)
routerlist_retry_directory_downloads(now);
}
}
}
/** Return 1 if any of our entry guards have descriptors that
* are marked with purpose 'bridge' and are running. Else return 0.
*
* We use this function to decide if we're ready to start building
* circuits through our bridges, or if we need to wait until the
* directory "server/authority" requests finish. */
int
any_bridge_descriptors_known(void)
{
tor_assert(get_options()->UseBridges);
return choose_random_entry(NULL)!=NULL ? 1 : 0;
}
/** Return 1 if we have at least one descriptor for a bridge and
* all descriptors we know are down. Else return 0. If act is
* 1, then mark the down bridges up; else just observe and report. */
static int
bridges_retry_helper(int act)
{
routerinfo_t *ri;
int any_known = 0;
int any_running = 0;
if (!entry_guards)
entry_guards = smartlist_create();
SMARTLIST_FOREACH(entry_guards, entry_guard_t *, e,
{
ri = router_get_by_digest(e->identity);
if (ri && ri->purpose == ROUTER_PURPOSE_BRIDGE) {
any_known = 1;
if (ri->is_running)
any_running = 1; /* some bridge is both known and running */
else if (act) { /* mark it for retry */
ri->is_running = 1;
e->can_retry = 1;
e->bad_since = 0;
}
}
});
return any_known && !any_running;
}
/** Do we know any descriptors for our bridges, and are they all
* down? */
int
bridges_known_but_down(void)
{
return bridges_retry_helper(0);
}
/** Mark all down known bridges up. */
void
bridges_retry_all(void)
{
bridges_retry_helper(1);
}
/** Release all storage held by the list of entry guards and related
* memory structs. */
void
entry_guards_free_all(void)
{
if (entry_guards) {
SMARTLIST_FOREACH(entry_guards, entry_guard_t *, e,
entry_guard_free(e));
smartlist_free(entry_guards);
entry_guards = NULL;
}
clear_bridge_list();
smartlist_free(bridge_list);
bridge_list = NULL;
}