nihilist/tor
1
0
Fork 0
mirror of https://gitlab.torproject.org/tpo/core/tor.git synced 2024-09-22 14:04:58 +02:00
Code Issues Packages Projects Releases Wiki Activity
d1c094637d
tor/src/or/circuitbuild.c

1990 lines
63 KiB
C
Raw Blame History

/* Copyright 2001 Matej Pfajfar.
* Copyright 2001-2004 Roger Dingledine.
* Copyright 2004-2005 Roger Dingledine, Nick Mathewson. */
/* 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;
/** A helper_node_t represents our information about a chosen fixed entry, or
* "helper" node. 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 down_since; /**< 0 if this router is currently up, or the time at which
* it was observed to go down. */
time_t unlisted_since; /**< 0 if this router is currently listed, or the time
* at which it became unlisted */
} helper_node_t;
/** A list of our chosen helper nodes. */
static smartlist_t *helper_nodes = NULL;
static int helper_nodes_dirty = 0;
/********* END VARIABLES ************/
static int circuit_deliver_create_cell(circuit_t *circ,
uint8_t cell_type, char *payload);
static int onion_pick_cpath_exit(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(uint8_t purpose, crypt_path_t **head_ptr,
cpath_build_state_t *state);
static int count_acceptable_routers(smartlist_t *routers);
static int onion_append_hop(crypt_path_t **head_ptr, extend_info_t *choice);
static void pick_helper_nodes(void);
static routerinfo_t *choose_random_helper(void);
static void clear_helper_nodes(void);
static void remove_dead_helpers(void);
static void helper_nodes_changed(void);
/** Iterate over values of circ_id, starting from conn-\>next_circ_id,
* and with the high bit specified by circ_id_type (see
* decide_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(connection_t *conn)
{
uint16_t test_circ_id;
int attempts=0;
uint16_t high_bit;
tor_assert(conn);
tor_assert(conn->type == CONN_TYPE_OR);
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 vulnerability.
*/
log_fn(LOG_WARN,"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 <b>verbose</b> is false, allocate and return a comma-separated
* list of the currently built elements of circuit_t. If
* <b>verbose</b> is true, also list information about link status in
* a more verbose format using spaces.
*/
char *
circuit_list_path(circuit_t *circ, int verbose)
{
crypt_path_t *hop;
smartlist_t *elements;
const char *states[] = {"closed", "waiting for keys", "open"};
char buf[128];
char *s;
tor_assert(CIRCUIT_IS_ORIGIN(circ));
elements = smartlist_create();
if (verbose) {
const char *nickname = build_state_get_exit_nickname(circ->build_state);
tor_snprintf(buf, sizeof(buf)-1, "%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->state == CIRCUIT_STATE_OPEN ? "" : ", exit ",
circ->state == CIRCUIT_STATE_OPEN ? "" :
(nickname?nickname:"*unnamed*"));
smartlist_add(elements, tor_strdup(buf));
}
hop = circ->cpath;
do {
const char *elt;
if (!hop)
break;
if (!verbose && hop->state != CPATH_STATE_OPEN)
break;
if (!hop->extend_info)
break;
elt = hop->extend_info->nickname;
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);
} else {
smartlist_add(elements, tor_strdup(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;
}
/** Log, at severity <b>severity</b>, 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, circuit_t *circ)
{
char *s = circuit_list_path(circ,1);
log_fn(severity,"%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.
*/
void
circuit_rep_hist_note_result(circuit_t *circ)
{
crypt_path_t *hop;
char *prev_digest = NULL;
routerinfo_t *router;
hop = circ->cpath;
if (!hop) {
/* XXX
* if !hop, then we're not the beginning of this circuit.
* for now, just forget about it. later, we should remember when
* extends-through-us failed, too.
*/
return;
}
if (server_mode(get_options())) {
routerinfo_t *me = router_get_my_routerinfo();
tor_assert(me);
prev_digest = me->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->identity_digest);
else {
rep_hist_note_extend_failed(prev_digest, router->identity_digest);
break;
}
}
prev_digest = router->identity_digest;
} else {
prev_digest = NULL;
}
hop=hop->next;
} while (hop!=circ->cpath);
}
/** A helper function for circuit_dump_by_conn() below. Log a bunch
* of information about circuit <b>circ</b>.
*/
static void
circuit_dump_details(int severity, circuit_t *circ, int poll_index,
const char *type, int this_circid, int other_circid)
{
log(severity,"Conn %d has %s circuit: circID %d (other side %d), state %d (%s), born %d:",
poll_index, type, this_circid, other_circid, circ->state,
circuit_state_to_string(circ->state), (int)circ->timestamp_created);
if (CIRCUIT_IS_ORIGIN(circ)) { /* circ starts at this node */
circuit_log_path(severity, circ);
}
}
/** Log, at severity <b>severity</b>, information about each circuit
* that is connected to <b>conn</b>.
*/
void
circuit_dump_by_conn(connection_t *conn, int severity)
{
circuit_t *circ;
connection_t *tmpconn;
for (circ=global_circuitlist;circ;circ = circ->next) {
if (circ->marked_for_close)
continue;
if (circ->p_conn == conn)
circuit_dump_details(severity, circ, conn->poll_index, "App-ward",
circ->p_circ_id, circ->n_circ_id);
for (tmpconn=circ->p_streams; tmpconn; tmpconn=tmpconn->next_stream) {
if (tmpconn == conn) {
circuit_dump_details(severity, circ, conn->poll_index, "App-ward",
circ->p_circ_id, circ->n_circ_id);
}
}
if (circ->n_conn == conn)
circuit_dump_details(severity, circ, conn->poll_index, "Exit-ward",
circ->n_circ_id, circ->p_circ_id);
for (tmpconn=circ->n_streams; tmpconn; tmpconn=tmpconn->next_stream) {
if (tmpconn == conn) {
circuit_dump_details(severity, circ, conn->poll_index, "Exit-ward",
circ->n_circ_id, circ->p_circ_id);
}
}
if (!circ->n_conn && circ->n_addr && circ->n_port &&
circ->n_addr == conn->addr &&
circ->n_port == conn->port &&
!memcmp(conn->identity_digest, circ->n_conn_id_digest, DIGEST_LEN)) {
circuit_dump_details(severity, circ, conn->poll_index, "Pending",
circ->n_circ_id, circ->p_circ_id);
}
}
}
/** 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(circuit_t *circ)
{
int r;
again:
r = onion_extend_cpath(circ->purpose, &circ->cpath, circ->build_state);
// || !CIRCUIT_IS_ORIGIN(circ)) { // wtf? -rd
if (r < 0) {
log_fn(LOG_INFO,"Generating cpath hop failed.");
return -1;
}
if (r == 0)
goto again;
return 0; /* if r == 1 */
}
/** Create and return a new circuit. Initialize its purpose and
* build-state based on our arguments. */
circuit_t *
circuit_init(uint8_t purpose, int need_uptime, int need_capacity, int internal)
{
circuit_t *circ = circuit_new(0, NULL); /* sets circ->p_circ_id and circ->p_conn */
circ->state = CIRCUIT_STATE_OR_WAIT;
circ->build_state = tor_malloc_zero(sizeof(cpath_build_state_t));
circ->build_state->need_uptime = need_uptime;
circ->build_state->need_capacity = need_capacity;
circ->build_state->is_internal = internal;
circ->purpose = purpose;
return circ;
}
/** Build a new circuit for <b>purpose</b>. If <b>info/b>
* 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.
*/
circuit_t *
circuit_establish_circuit(uint8_t purpose, extend_info_t *info,
int need_uptime, int need_capacity, int internal)
{
circuit_t *circ;
circ = circuit_init(purpose, need_uptime, need_capacity, internal);
if (onion_pick_cpath_exit(circ, info) < 0 ||
onion_populate_cpath(circ) < 0) {
circuit_mark_for_close(circ);
return NULL;
}
control_event_circuit_status(circ, CIRC_EVENT_LAUNCHED);
if (circuit_handle_first_hop(circ) < 0) {
circuit_mark_for_close(circ);
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, -1 if circ should be marked-for-close. */
int
circuit_handle_first_hop(circuit_t *circ)
{
crypt_path_t *firsthop;
connection_t *n_conn;
char tmpbuf[INET_NTOA_BUF_LEN+1];
struct in_addr in;
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_fn(LOG_DEBUG,"Looking for firsthop '%s:%u'",tmpbuf,
firsthop->extend_info->port);
/* imprint the circuit with its future n_conn->id */
memcpy(circ->n_conn_id_digest, firsthop->extend_info->identity_digest,
DIGEST_LEN);
n_conn = connection_get_by_identity_digest(
firsthop->extend_info->identity_digest, CONN_TYPE_OR);
if (!n_conn || n_conn->state != OR_CONN_STATE_OPEN) { /* not currently connected */
circ->n_addr = firsthop->extend_info->addr;
circ->n_port = firsthop->extend_info->port;
if (!n_conn) { /* 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_fn(LOG_INFO,"connect to firsthop failed. Closing.");
return -1;
}
}
log_fn(LOG_DEBUG,"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->n_addr = n_conn->addr;
circ->n_port = n_conn->port;
circ->n_conn = n_conn;
log_fn(LOG_DEBUG,"Conn open. Delivering first onion skin.");
if (circuit_send_next_onion_skin(circ) < 0) {
log_fn(LOG_INFO,"circuit_send_next_onion_skin failed.");
return -1;
}
}
return 0;
}
/** Find circuits that are waiting on <b>or_conn</b> to become open,
* if any, 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(connection_t *or_conn, int status)
{
circuit_t *circ;
log_fn(LOG_DEBUG,"or_conn to %s, status=%d",
or_conn->nickname ? or_conn->nickname : "NULL", status);
for (circ=global_circuitlist;circ;circ = circ->next) {
if (circ->marked_for_close)
continue;
if (circ->state == CIRCUIT_STATE_OR_WAIT &&
!circ->n_conn &&
circ->n_addr == or_conn->addr &&
circ->n_port == or_conn->port &&
!memcmp(or_conn->identity_digest, circ->n_conn_id_digest, DIGEST_LEN)) {
if (!status) { /* or_conn failed; close circ */
log_fn(LOG_INFO,"or_conn failed. Closing circ.");
circuit_mark_for_close(circ);
continue;
}
log_fn(LOG_DEBUG,"Found circ %d, sending create cell.", circ->n_circ_id);
circ->n_conn = or_conn;
memcpy(circ->n_conn_id_digest, or_conn->identity_digest, DIGEST_LEN);
if (CIRCUIT_IS_ORIGIN(circ)) {
if (circuit_send_next_onion_skin(circ) < 0) {
log_fn(LOG_INFO,"send_next_onion_skin failed; circuit marked for closing.");
circuit_mark_for_close(circ);
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 */
if (circuit_deliver_create_cell(circ,CELL_CREATE,circ->onionskin) < 0) {
circuit_mark_for_close(circ);
continue;
}
}
}
}
}
/** Find a new circid that isn't currently in use by the outgoing
* circuit <b>circ</b>, and deliver a cell of type <b>cell_type</b>
* (either CELL_CREATE or CELL_CREATE_FAST) with payload <b>payload</b>
* 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, char *payload)
{
cell_t cell;
uint16_t id;
tor_assert(circ);
tor_assert(circ->n_conn);
tor_assert(circ->n_conn->type == CONN_TYPE_OR);
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_fn(LOG_WARN,"failed to get unique circID.");
return -1;
}
log_fn(LOG_DEBUG,"Chosen circID %u.", id);
circuit_set_circid_orconn(circ, id, circ->n_conn, N_CONN_CHANGED);
memset(&cell, 0, sizeof(cell_t));
cell.command = cell_type;
cell.circ_id = circ->n_circ_id;
memcpy(cell.payload, payload, ONIONSKIN_CHALLENGE_LEN);
connection_or_write_cell_to_buf(&cell, circ->n_conn);
return 0;
}
extern int has_completed_circuit;
/** 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 -1 if we want to tear down circ, else return 0.
*/
int
circuit_send_next_onion_skin(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);
tor_assert(CIRCUIT_IS_ORIGIN(circ));
if (circ->cpath->state == CPATH_STATE_CLOSED) {
uint8_t cell_type;
log_fn(LOG_DEBUG,"First skin; sending create cell.");
router = router_get_by_digest(circ->n_conn->identity_digest);
if (1 || /* Disable this '1' once we believe CREATE_FAST works. XXXX */
(get_options()->ORPort || !router || !router->platform ||
!tor_version_as_new_as(router->platform, "0.1.0.6-rc"))) {
/* 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_fn(LOG_WARN,"onion_skin_create (first hop) failed.");
return -1;
}
} else {
/* We are not an OR, and we building the first hop of a circuit to
* a new OR: we can be speedy. */
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(circ, cell_type, payload) < 0)
return -1;
circ->cpath->state = CPATH_STATE_AWAITING_KEYS;
circ->state = CIRCUIT_STATE_BUILDING;
log_fn(LOG_DEBUG,"first skin; finished sending create cell.");
} else {
tor_assert(circ->cpath->state == CPATH_STATE_OPEN);
tor_assert(circ->state == CIRCUIT_STATE_BUILDING);
log_fn(LOG_DEBUG,"starting to send subsequent skin.");
hop = onion_next_hop_in_cpath(circ->cpath);
if (!hop) {
/* done building the circuit. whew. */
circ->state = CIRCUIT_STATE_OPEN;
log_fn(LOG_INFO,"circuit built!");
circuit_reset_failure_count(0);
if (!has_completed_circuit) {
or_options_t *options = get_options();
has_completed_circuit=1;
log(LOG_NOTICE,"Tor has successfully opened a circuit. Looks like it's working.");
/* XXX009 Log a count of known routers here */
if (server_mode(options) && !check_whether_orport_reachable())
log(LOG_NOTICE,"Now checking whether ORPort %s%s reachable... (this may take several minutes)",
options->DirPort ? "and DirPort " : "",
options->DirPort ? "are" : "is");
}
circuit_rep_hist_note_result(circ);
circuit_has_opened(circ); /* do other actions as necessary */
return 0;
}
*(uint32_t*)payload = htonl(hop->extend_info->addr);
*(uint16_t*)(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_fn(LOG_WARN,"onion_skin_create failed.");
return -1;
}
log_fn(LOG_DEBUG,"Sending extend relay cell.");
/* send it to hop->prev, because it will transfer
* it to a create cell and then send to hop */
if (connection_edge_send_command(NULL, 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 forward by <b>seconds_elapsed</b>. 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)
{
log(LOG_NOTICE,"Your clock just jumped %d seconds forward; assuming established circuits no longer work.", seconds_elapsed);
has_completed_circuit=0; /* so it'll log when it works again */
circuit_mark_all_unused_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 in
* a create cell.
*/
int
circuit_extend(cell_t *cell, circuit_t *circ)
{
connection_t *n_conn;
relay_header_t rh;
char *onionskin;
char *id_digest=NULL;
if (circ->n_conn) {
log_fn(LOG_WARN,"n_conn already set. Bug/attack. Closing.");
return -1;
}
relay_header_unpack(&rh, cell->payload);
if (rh.length < 4+2+ONIONSKIN_CHALLENGE_LEN+DIGEST_LEN) {
log_fn(LOG_WARN, "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_get_by_identity_digest(id_digest, CONN_TYPE_OR);
if (!n_conn || n_conn->state != OR_CONN_STATE_OPEN) {
/* Note that this will close circuits where the onion has the same
* router twice in a row in the path. I think that's ok.
*/
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_fn(LOG_INFO,"Next router (%s:%d) not connected. Connecting.",
tmpbuf, circ->n_port);
memcpy(circ->onionskin, onionskin, ONIONSKIN_CHALLENGE_LEN);
circ->state = 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) {
circ->n_addr = n_conn->addr;
circ->n_port = n_conn->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_fn(LOG_INFO,"Launching n_conn failed. Closing.");
return -1;
}
log_fn(LOG_DEBUG,"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->addr;
circ->n_port = n_conn->port;
circ->n_conn = n_conn;
memcpy(circ->n_conn_id_digest, n_conn->identity_digest, DIGEST_LEN);
log_fn(LOG_DEBUG,"n_conn is %s:%u",n_conn->address,n_conn->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, 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));
// log_fn(LOG_DEBUG,"hop init digest forward 0x%.8x, backward 0x%.8x.",
// (unsigned int)*(uint32_t*)key_data, (unsigned int)*(uint32_t*)(key_data+20));
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);
// log_fn(LOG_DEBUG,"hop init cipher forward 0x%.8x, backward 0x%.8x.",
// (unsigned int)*(uint32_t*)(key_data+40), (unsigned int)*(uint32_t*)(key_data+40+16));
if (!(cpath->f_crypto =
crypto_create_init_cipher(key_data+(2*DIGEST_LEN),1))) {
log(LOG_WARN,"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(LOG_WARN,"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 <b>reply</b> (the second DH key, plus KH).
* DOCDOC reply_type.
*
* Calculate the appropriate keys and digests, make sure KH is
* correct, and initialize this hop of the cpath.
*
* Return -1 if we want to mark circ for close, else return 0.
*/
int
circuit_finish_handshake(circuit_t *circ, uint8_t reply_type, char *reply)
{
char keys[CPATH_KEY_MATERIAL_LEN];
crypt_path_t *hop;
tor_assert(CIRCUIT_IS_ORIGIN(circ));
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_fn(LOG_WARN,"got extended when circ already built? Closing.");
return -1;
}
}
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_fn(LOG_WARN,"onion_skin_client_handshake failed.");
return -1;
}
/* 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_fn(LOG_WARN,"fast_client_handshake failed.");
return -1;
}
memcpy(hop->handshake_digest, reply+DIGEST_LEN, DIGEST_LEN);
} else {
log_fn(LOG_WARN,"CREATED cell type did not match CREATE cell type.");
return -1;
}
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 -1;
}
hop->state = CPATH_STATE_OPEN;
log_fn(LOG_INFO,"Finished building circuit hop:");
circuit_log_path(LOG_INFO,circ);
control_event_circuit_status(circ, CIRC_EVENT_EXTENDED);
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(circuit_t *circ, crypt_path_t *layer)
{
// crypt_path_t *victim;
// connection_t *stream;
tor_assert(circ);
tor_assert(CIRCUIT_IS_ORIGIN(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(circ);
return 0;
#if 0
while (layer->next != circ->cpath) {
/* we need to clear out layer->next */
victim = layer->next;
log_fn(LOG_DEBUG, "Killing a layer of the cpath.");
for (stream = circ->p_streams; stream; stream=stream->next_stream) {
if (stream->cpath_layer == victim) {
log_fn(LOG_INFO, "Marking stream %d for close.", 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_fn(LOG_INFO, "finished");
return 0;
#endif
}
/** Given a response payload and keys, initialize, then send a created
* cell back.
*/
int
onionskin_answer(circuit_t *circ, uint8_t cell_type, char *payload, 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;
circ->state = CIRCUIT_STATE_OPEN;
memcpy(cell.payload, payload,
cell_type == CELL_CREATED ? ONIONSKIN_REPLY_LEN : DIGEST_LEN*2);
log_fn(LOG_INFO,"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_fn(LOG_WARN,"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);
connection_or_write_cell_to_buf(&cell, circ->p_conn);
log_fn(LOG_DEBUG,"Finished sending 'created' cell.");
if (!is_local_IP(circ->p_conn->addr) &&
tor_tls_is_server(circ->p_conn->tls)) {
/* 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 <b>purpose</b>.
* Default length is 3 + the number of endpoints that would give something
* away. If the routerlist <b>routers</b> 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(double cw, uint8_t purpose, smartlist_t *routers)
{
int num_acceptable_routers;
int routelen;
tor_assert(cw >= 0.);
tor_assert(cw < 1.);
tor_assert(routers);
#ifdef TOR_PERF
routelen = 2;
#else
if (purpose == CIRCUIT_PURPOSE_C_GENERAL)
routelen = 3;
else if (purpose == CIRCUIT_PURPOSE_TESTING)
routelen = 3;
else if (purpose == CIRCUIT_PURPOSE_C_INTRODUCING)
routelen = 4;
else if (purpose == CIRCUIT_PURPOSE_C_ESTABLISH_REND)
routelen = 3;
else if (purpose == CIRCUIT_PURPOSE_S_ESTABLISH_INTRO)
routelen = 3;
else if (purpose == CIRCUIT_PURPOSE_S_CONNECT_REND)
routelen = 4;
else {
log_fn(LOG_WARN,"Bug: unhandled purpose %d", purpose);
tor_fragile_assert();
return -1;
}
#endif
log_fn(LOG_DEBUG,"Chosen route length %d (%d routers available).",routelen,
smartlist_len(routers));
num_acceptable_routers = count_acceptable_routers(routers);
if (num_acceptable_routers < 2) {
log_fn(LOG_INFO,"Not enough acceptable routers (%d). Discarding this circuit.",
num_acceptable_routers);
return -1;
}
if (num_acceptable_routers < routelen) {
log_fn(LOG_INFO,"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;
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 <b>router</b> can handle one or more of the ports in
* <b>needed_ports</b>, 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 = router_compare_addr_to_addr_policy(0, port, router->exit_policy);
if (r != ADDR_POLICY_REJECTED && r != ADDR_POLICY_PROBABLY_REJECTED)
return 1;
}
return 0;
}
/** How many circuits do we want simultaneously in-progress to handle
* a given stream?
*/
#define MIN_CIRCUITS_HANDLING_STREAM 2
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(conn) &&
!circuit_stream_is_being_handled(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, j;
int n_pending_connections = 0;
connection_t **carray;
int n_connections;
int best_support = -1;
int n_best_support=0;
smartlist_t *sl, *preferredexits, *preferredentries, *excludedexits;
routerinfo_t *router;
or_options_t *options = get_options();
preferredentries = smartlist_create();
add_nickname_list_to_smartlist(preferredentries,options->EntryNodes,1);
get_connection_array(&carray, &n_connections);
/* 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.
*/
for (i = 0; i < n_connections; ++i) {
if (ap_stream_wants_exit_attention(carray[i]))
++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) {
n_supported[i] = -1;
// log_fn(LOG_DEBUG,"Skipping node %s (index %d) -- directory says it's not running.",
// router->nickname, i);
continue; /* skip routers that are known to be down */
}
if (router_is_unreliable(router, need_uptime, need_capacity)) {
n_supported[i] = -1;
continue; /* skip routers that are not suitable */
}
if (!router->is_verified &&
(!(options->_AllowUnverified & ALLOW_UNVERIFIED_EXIT) ||
router_is_unreliable(router, 1, 1))) {
/* if it's unverified, and either we don't want it or it's unsuitable */
n_supported[i] = -1;
// log_fn(LOG_DEBUG,"Skipping node %s (index %d) -- unverified router.",
// router->nickname, i);
continue; /* skip unverified 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 */
}
if (smartlist_len(preferredentries)==1 &&
router == (routerinfo_t*)smartlist_get(preferredentries, 0)) {
n_supported[i] = -1;
// log_fn(LOG_DEBUG,"Skipping node %s (index %d) -- it's our only preferred entry node.", router->nickname, i);
continue;
}
n_supported[i] = 0;
for (j = 0; j < n_connections; ++j) { /* iterate over connections */
if (!ap_stream_wants_exit_attention(carray[j]))
continue; /* Skip everything but APs in CIRCUIT_WAIT */
if (connection_ap_can_use_exit(carray[j], 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_fn(LOG_INFO, "Found %d servers that might support %d/%d pending connections.",
n_best_support, best_support, 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);
} 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 = circuit_get_unhandled_ports(time(NULL));
if (best_support == -1) {
log(LOG_NOTICE, "All routers are down or middleman -- choosing a doomed exit at random.");
}
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);
router = routerlist_sl_choose_by_bandwidth(sl);
if (router)
break;
}
SMARTLIST_FOREACH(needed_ports, uint16_t *, cp, tor_free(cp));
smartlist_free(needed_ports);
}
smartlist_free(preferredexits);
smartlist_free(preferredentries);
smartlist_free(excludedexits);
smartlist_free(sl);
tor_free(n_supported);
if (router) {
log_fn(LOG_INFO, "Chose exit server '%s'", router->nickname);
return router;
}
if (options->StrictExitNodes)
log_fn(LOG_WARN, "No exit routers seem to be running; can't choose an exit.");
return NULL;
}
/** Return a pointer to a suitable router to be the exit node for the
* circuit of purpose <b>purpose</b> 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)
{
routerinfo_t *r;
or_options_t *options = get_options();
switch (purpose) {
case CIRCUIT_PURPOSE_C_GENERAL:
return choose_good_exit_server_general(dir, need_uptime, need_capacity);
case CIRCUIT_PURPOSE_C_ESTABLISH_REND:
r = router_choose_random_node(options->RendNodes, options->RendExcludeNodes,
NULL, need_uptime, need_capacity,
options->_AllowUnverified & ALLOW_UNVERIFIED_RENDEZVOUS, 0);
return r;
}
log_fn(LOG_WARN,"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 <b>exit</b> if provided). Store these in the
* cpath. Return 0 if ok, -1 if circuit should be closed. */
static int
onion_pick_cpath_exit(circuit_t *circ, extend_info_t *exit)
{
cpath_build_state_t *state = circ->build_state;
routerlist_t *rl;
int r;
router_get_routerlist(&rl);
if (!rl) {
log_fn(LOG_WARN,"router_get_routerlist returned empty list; closing circ.");
return -1;
}
r = new_route_len(get_options()->PathlenCoinWeight, circ->purpose, 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_fn(LOG_INFO,"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->purpose, rl,
state->need_uptime, state->need_capacity);
if (!router) {
log_fn(LOG_WARN,"failed to choose an exit server");
return -1;
}
exit = extend_info_from_router(router);
}
state->chosen_exit = exit;
return 0;
}
/** Give <b>circ</b> a new exit destination to <b>exit</b>, 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(circuit_t *circ, extend_info_t *info)
{
cpath_build_state_t *state;
tor_assert(info);
tor_assert(circ && CIRCUIT_IS_ORIGIN(circ));
state = circ->build_state;
tor_assert(state);
if (state->chosen_exit)
extend_info_free(state->chosen_exit);
state->chosen_exit = extend_info_dup(info);
++circ->build_state->desired_path_len;
onion_append_hop(&circ->cpath, info);
return 0;
}
/** DOCDOC */
int
circuit_extend_to_new_exit(circuit_t *circ, extend_info_t *info)
{
circuit_append_new_exit(circ, info);
circ->state = CIRCUIT_STATE_BUILDING;
if (circuit_send_next_onion_skin(circ)<0) {
log_fn(LOG_WARN, "Couldn't extend circuit to new point '%s'.",
info->nickname);
circuit_mark_for_close(circ);
return -1;
}
return 0;
}
/** Return the number of routers in <b>routers</b> 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;i<n;i++) {
r = smartlist_get(routers, i);
// log_fn(LOG_DEBUG,"Contemplating whether router %d (%s) is a new option...",
// i, r->nickname);
if (r->is_running == 0) {
// log_fn(LOG_DEBUG,"Nope, the directory says %d is not running.",i);
goto next_i_loop;
}
if (r->is_verified == 0) {
// log_fn(LOG_DEBUG,"Nope, the directory says %d is not verified.",i);
/* XXXX009 But unverified routers *are* sometimes acceptable. */
goto next_i_loop;
}
num++;
// log_fn(LOG_DEBUG,"I like %d. num_acceptable_routers now %d.",i, num);
next_i_loop:
; /* C requires an explicit statement after the label */
}
return num;
}
/** Add <b>new_hop</b> to the end of the doubly-linked-list <b>head_ptr</b>.
*
* 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;
}
}
/** DOCDOC */
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;
log_fn(LOG_DEBUG, "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);
}
if ((r = routerlist_find_my_routerinfo())) {
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);
}
}
choice = router_choose_random_node(NULL, get_options()->ExcludeNodes, excluded,
state->need_uptime, state->need_capacity,
get_options()->_AllowUnverified & ALLOW_UNVERIFIED_MIDDLE, 0);
smartlist_free(excluded);
return choice;
}
/** Pick a good entry server for the circuit to be built according to
* <b>state</b>. 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 using helper nodes,
* return one.
*
* If <b>state</b> is NULL, we're choosing entries to serve as helper nodes,
* not for any particular circuit.
*/
static routerinfo_t *
choose_good_entry_server(cpath_build_state_t *state)
{
routerinfo_t *r, *choice;
smartlist_t *excluded = smartlist_create();
or_options_t *options = get_options();
if (state && options->UseHelperNodes) {
return choose_random_helper();
}
if (state && (r = build_state_get_exit_router(state))) {
smartlist_add(excluded, r);
routerlist_add_family(excluded, r);
}
if ((r = routerlist_find_my_routerinfo())) {
smartlist_add(excluded, r);
routerlist_add_family(excluded, r);
}
if (firewall_is_fascist()) {
/* exclude all ORs that listen on the wrong port */
routerlist_t *rl;
int i;
router_get_routerlist(&rl);
if (!rl)
return NULL;
for (i=0; i < smartlist_len(rl->routers); i++) {
r = smartlist_get(rl->routers, i);
if (!fascist_firewall_allows_address(r->addr,r->or_port))
smartlist_add(excluded, r);
}
}
choice = router_choose_random_node(options->EntryNodes, options->ExcludeNodes,
excluded, state ? state->need_uptime : 1,
state ? state->need_capacity : 0,
options->_AllowUnverified & ALLOW_UNVERIFIED_ENTRY,
options->StrictEntryNodes);
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 <b>head_ptr</b>,
* based on <b>state</b>. Append the hop info to head_ptr.
*/
static int
onion_extend_cpath(uint8_t purpose, crypt_path_t **head_ptr,
cpath_build_state_t *state)
{
int cur_len;
crypt_path_t *cpath;
extend_info_t *info = NULL;
smartlist_t *excludednodes;
tor_assert(head_ptr);
if (!*head_ptr) {
cur_len = 0;
} else {
cur_len = 1;
for (cpath = *head_ptr; cpath->next != *head_ptr; cpath = cpath->next) {
++cur_len;
}
}
if (cur_len >= state->desired_path_len) {
log_fn(LOG_DEBUG, "Path is complete: %d steps long",
state->desired_path_len);
return 1;
}
log_fn(LOG_DEBUG, "Path is %d long; we want %d", cur_len,
state->desired_path_len);
excludednodes = smartlist_create();
add_nickname_list_to_smartlist(excludednodes,get_options()->ExcludeNodes,0);
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(state);
if (r)
info = extend_info_from_router(r);
} else {
routerinfo_t *r =
choose_good_middle_server(purpose, state, *head_ptr, cur_len);
if (r)
info = extend_info_from_router(r);
}
smartlist_free(excludednodes);
if (!info) {
log_fn(LOG_WARN,"Failed to find node for hop %d of our path. Discarding this circuit.", cur_len);
return -1;
}
log_fn(LOG_DEBUG,"Chose router %s for hop %d (exit is %s)",
info->nickname, cur_len+1, build_state_get_exit_nickname(state));
onion_append_hop(head_ptr, info);
extend_info_free(info);
return 0;
}
/** Create a new hop, annotate it with information about its
* corresponding router <b>choice</b>, and append it to the
* end of the cpath <b>head_ptr</b>. */
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 and return a new extend_info_t that can be used to build a
* circuit to or through the router <b>r</b>. */
extend_info_t *
extend_info_from_router(routerinfo_t *r)
{
extend_info_t *info;
tor_assert(r);
info = tor_malloc_zero(sizeof(extend_info_t));
strlcpy(info->nickname, r->nickname, sizeof(info->nickname));
memcpy(info->identity_digest, r->identity_digest, DIGEST_LEN);
info->onion_key = crypto_pk_dup_key(r->onion_pkey);
info->addr = r->addr;
info->port = r->or_port;
return info;
}
/** Release storage held by an extend_info_t struct. */
void
extend_info_free(extend_info_t *info)
{
tor_assert(info);
crypto_free_pk_env(info->onion_key);
tor_free(info);
}
/** Allocate and return a new extend_info_t with the same contents as
* <b>info</b>. */
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));
newinfo->onion_key = crypto_pk_dup_key(info->onion_key);
return newinfo;
}
/**
* Return the routerinfo_t for the chosen exit router in <b>state</b>. 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 <b>state</b>. 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;
}
/** Return the number of helper nodes that we think are usable. */
static int
num_live_helpers(void)
{
int n = 0;
if (! helper_nodes)
return 0;
SMARTLIST_FOREACH(helper_nodes, helper_node_t *, helper,
if (! helper->down_since && ! helper->unlisted_since)
++n;);
return n;
}
/** If the use of helper nodes is configured, choose more helper nodes until
* we have enough in the list. */
static void
pick_helper_nodes(void)
{
or_options_t *options = get_options();
int changed = 0;
if (! options->UseHelperNodes)
return;
if (!helper_nodes)
helper_nodes = smartlist_create();
while (smartlist_len(helper_nodes) < options->NumHelperNodes) {
routerinfo_t *entry = choose_good_entry_server(NULL);
/* XXXX deal with duplicate entries. */
helper_node_t *helper = tor_malloc_zero(sizeof(helper_node_t));
/* XXXX Downgrade this to info before release. */
log_fn(LOG_NOTICE, "Chose '%s' as helper node.", entry->nickname);
strlcpy(helper->nickname, entry->nickname, sizeof(helper->nickname));
memcpy(helper->identity, entry->identity_digest, DIGEST_LEN);
smartlist_add(helper_nodes, helper);
changed = 1;
}
if (changed)
helper_nodes_changed();
}
/** Remove all elements from the list of helper nodes */
static void
clear_helper_nodes(void)
{
SMARTLIST_FOREACH(helper_nodes, helper_node_t *, h, tor_free(h));
smartlist_clear(helper_nodes);
helper_nodes_changed();
}
/** How long (in seconds) do we allow a helper node to be nonfunctional before
* we give up on it? */
#define HELPER_ALLOW_DOWNTIME 48*60*60
/** How long (in seconds) do we allow a helper node to be unlisted in the
* directory before we give up on it? */
#define HELPER_ALLOW_UNLISTED 48*60*60
/** Remove all helper nodes that have been down or unlisted for so long that
* we don't think they'll come up again. */
static void
remove_dead_helpers(void)
{
char dbuf[HEX_DIGEST_LEN+1];
char tbuf[ISO_TIME_LEN+1];
time_t now = time(NULL);
int i;
for (i = 0; i < smartlist_len(helper_nodes); ) {
helper_node_t *helper = smartlist_get(helper_nodes, i);
const char *why = NULL;
time_t since = 0;
if (helper->unlisted_since + HELPER_ALLOW_UNLISTED > now) {
why = "unlisted";
since = helper->unlisted_since;
} else if (helper->down_since + HELPER_ALLOW_DOWNTIME > now) {
why = "down";
since = helper->unlisted_since;
}
if (why) {
base16_encode(dbuf, sizeof(dbuf), helper->identity, DIGEST_LEN);
format_local_iso_time(tbuf, since);
log_fn(LOG_WARN, "Helper node '%s' (%s) has been %s since %s; removing.",
helper->nickname, dbuf, why, tbuf);
tor_free(helper);
smartlist_del(helper_nodes, i);
helper_nodes_changed();
} else
++i;
}
}
/** A new directory or router-status has arrived; update the down/listed status
* of the helper nodes.
*
* A helper is 'down' if the directory lists it as nonrunning, or if we tried
* to connect to it and failed. A helper is 'unlisted' if the directory
* doesn't include it.
*/
void
helper_nodes_set_status_from_directory(void)
{
/* Don't call this on startup; only on a fresh download. Otherwise we'll
* think that things are unlisted. */
routerlist_t *routers;
time_t now;
int changed = 0;
if (! helper_nodes)
return;
router_get_routerlist(&routers);
if (! routers)
return;
now = time(NULL);
/*XXXX Most of these warns should be non-warns. */
SMARTLIST_FOREACH(helper_nodes, helper_node_t *, helper,
{
routerinfo_t *r = router_get_by_digest(helper->identity);
if (! r) {
if (! helper->unlisted_since) {
/* Watch out for skew here. XXXX */
helper->unlisted_since = routers->published_on;
++changed;
log_fn(LOG_WARN,"Helper node '%s' is not published in latest directory",
helper->nickname);
}
} else {
if (helper->unlisted_since) {
log_fn(LOG_WARN,"Helper node '%s' is listed again in latest directory",
helper->nickname);
++changed;
}
helper->unlisted_since = 0;
if (! r->is_running) {
if (! helper->down_since) {
helper->down_since = now;
log_fn(LOG_WARN, "Helper node '%s' is now down.", helper->nickname);
++changed;
}
} else {
if (helper->down_since) {
log_fn(LOG_WARN,"Helper node '%s' is up in latest directory",
helper->nickname);
++changed;
}
helper->down_since = 0;
}
}
});
if (changed) {
log_fn(LOG_WARN, " (%d/%d helpers are usable)",
num_live_helpers(), smartlist_len(helper_nodes));
helper_nodes_changed();
}
remove_dead_helpers();
pick_helper_nodes();
}
/** Called when a connection to an OR with the identity digest <b>digest</b>
* is established (<b>succeeded</b>==1) or has failed (<b>succeeded</b>==0).
* If the OR is a helper, change that helper's up/down status.
*/
void
helper_node_set_status(const char *digest, int succeeded)
{
if (! helper_nodes)
return;
SMARTLIST_FOREACH(helper_nodes, helper_node_t *, helper,
{
if (!memcmp(helper->identity, digest, DIGEST_LEN)) {
if (succeeded) {
if (helper->down_since) {
/*XXXX shouldn't warn. */
log_fn(LOG_WARN,
"Connection to formerly down helper node '%s' succeeded. "
"%d/%d helpers usable.", helper->nickname,
num_live_helpers(), smartlist_len(helper_nodes));
helper_nodes_changed();
}
helper->down_since = 0;
} else if (!helper->down_since) {
helper->down_since = time(NULL);
log_fn(LOG_WARN,
"Connection to helper node '%s' failed. %d/%d helpers usable.",
helper->nickname, num_live_helpers(), smartlist_len(helper_nodes));
helper_nodes_changed();
}
}
});
}
/** Pick a live (up and listed) helper node from the list of helpers. If
* no helpers are available, pick a new list. */
static routerinfo_t *
choose_random_helper(void)
{
smartlist_t *live_helpers = smartlist_create();
routerinfo_t *r;
if (! helper_nodes)
pick_helper_nodes();
retry:
SMARTLIST_FOREACH(helper_nodes, helper_node_t *, helper,
if (! helper->down_since && ! helper->unlisted_since) {
if ((r = router_get_by_digest(helper->identity))) {
smartlist_add(live_helpers, r);
}
});
if (! smartlist_len(live_helpers)) {
/* XXXX Is this right? What if network is down? */
log_fn(LOG_WARN, "No functional helper nodes found; picking a new set.");
clear_helper_nodes();
pick_helper_nodes();
goto retry;
}
r = smartlist_choose(live_helpers);
smartlist_free(live_helpers);
return r;
}
/** DOCDOC */
int
helper_nodes_parse_state(or_state_t *state, int set, const char **err)
{
helper_node_t *node = NULL;
smartlist_t *helpers = smartlist_create();
config_line_t *line;
*err = NULL;
for (line = state->HelperNodes; line; line = line->next) {
if (!strcasecmp(line->key, "HelperNode")) {
smartlist_t *args = smartlist_create();
node = tor_malloc_zero(sizeof(helper_node_t));
smartlist_add(helpers, node);
smartlist_split_string(args, line->value, " ",
SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
if (smartlist_len(args)<2) {
*err = "Too few arguments to HelperNode";
break;
}
if (!is_legal_nickname(smartlist_get(args,0))) {
*err = "Bad nickname for HelperNode";
break;
}
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) {
*err = "Bad hex digest for HelperNode";
break;
}
} else {
time_t when;
if (!node) {
*err = "HelperNodeDownSince/UnlistedSince without HelperNode";
break;
}
if (parse_iso_time(line->value, &when)<0) {
*err = "Bad time in HelperNodeDownSince/UnlistedSince";
break;
}
if (!strcasecmp(line->key, "HelperNodeDownSince"))
node->down_since = when;
else
node->unlisted_since = when;
}
}
if (*err || !set) {
SMARTLIST_FOREACH(helpers, helper_node_t *, h, tor_free(h));
smartlist_free(helpers);
}
if (!*err && set) {
if (helper_nodes) {
SMARTLIST_FOREACH(helper_nodes, helper_node_t *, h, tor_free(h));
smartlist_free(helper_nodes);
}
helper_nodes = helpers;
helper_nodes_dirty = 0;
}
return *err ? -1 : 0;
}
/** DOCDOC */
static void
helper_nodes_changed(void)
{
helper_nodes_dirty = 1;
or_state_save();
}
/** DOCDOC */
int
helper_nodes_update_state(or_state_t *state)
{
config_line_t **next, *line;
if (! helper_nodes_dirty)
return 0;
config_free_lines(state->HelperNodes);
next = &state->HelperNodes;
*next = NULL;
if (!helper_nodes)
helper_nodes = smartlist_create();
SMARTLIST_FOREACH(helper_nodes, helper_node_t *, h,
{
char dbuf[HEX_DIGEST_LEN+1];
*next = line = tor_malloc_zero(sizeof(config_line_t));
line->key = tor_strdup("HelperNode");
line->value = tor_malloc(HEX_DIGEST_LEN+MAX_NICKNAME_LEN+2);
base16_encode(dbuf, sizeof(dbuf), h->identity, DIGEST_LEN);
tor_snprintf(line->value,HEX_DIGEST_LEN+MAX_NICKNAME_LEN+2,
"%s %s", h->nickname, dbuf);
next = &(line->next);
if (h->down_since) {
*next = line = tor_malloc_zero(sizeof(config_line_t));
line->key = tor_strdup("HelperNodeDownSince");
line->value = tor_malloc(ISO_TIME_LEN+1);
format_iso_time(line->value, h->down_since);
next = &(line->next);
}
if (h->unlisted_since) {
*next = line = tor_malloc_zero(sizeof(config_line_t));
line->key = tor_strdup("HelperNodeUnlistedSince");
line->value = tor_malloc(ISO_TIME_LEN+1);
format_iso_time(line->value, h->unlisted_since);
next = &(line->next);
}
});
state->dirty = 1;
helper_nodes_dirty = 0;
return 1;
}
/** DOCDOC */
int
helper_nodes_getinfo_helper(const char *question, char **answer)
{
if (!strcmp(question,"helper-nodes")) {
smartlist_t *sl = smartlist_create();
char tbuf[ISO_TIME_LEN+1];
char dbuf[HEX_DIGEST_LEN+1];
if (!helper_nodes)
helper_nodes = smartlist_create();
SMARTLIST_FOREACH(helper_nodes, helper_node_t *, h,
{
size_t len = HEX_DIGEST_LEN+ISO_TIME_LEN+16;
char *c = tor_malloc(len);
const char *status = NULL;
time_t when = 0;
if (h->unlisted_since) {
when = h->unlisted_since;
status = "unlisted";
} else if (h->down_since) {
when = h->down_since;
status = "down";
} else {
status = "up";
}
base16_encode(dbuf, sizeof(dbuf), h->identity, DIGEST_LEN);
if (when) {
format_iso_time(tbuf, when);
tor_snprintf(c, len, "$%s %s %s\n", dbuf, status, tbuf);
} else {
tor_snprintf(c, len, "$%s %s\n", dbuf, 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;
}
Reference in New Issue View Git Blame Copy Permalink