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fdc5751c60
tor/src/or/circuit.c
Roger Dingledine fdc5751c60 bugfix: address that strcat vulnerability in circuit.c 
svn:r1273
2004-03-14 22:47:11 +00:00

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/* Copyright 2001,2002,2003 Roger Dingledine, Matej Pfajfar. */
/* See LICENSE for licensing information */
/* $Id$ */
#include "or.h"
extern or_options_t options; /* command-line and config-file options */
static int relay_crypt(circuit_t *circ, cell_t *cell, int cell_direction,
crypt_path_t **layer_hint, char *recognized);
static connection_t *relay_lookup_conn(circuit_t *circ, cell_t *cell, int cell_direction);
static void circuit_free_cpath_node(crypt_path_t *victim);
static uint16_t get_unique_circ_id_by_conn(connection_t *conn, int circ_id_type);
unsigned long stats_n_relay_cells_relayed = 0;
unsigned long stats_n_relay_cells_delivered = 0;
/********* START VARIABLES **********/
static circuit_t *global_circuitlist=NULL;
char *circuit_state_to_string[] = {
"doing handshakes", /* 0 */
"processing the onion", /* 1 */
"connecting to firsthop", /* 2 */
"open" /* 3 */
};
/********* END VARIABLES ************/
void circuit_add(circuit_t *circ) {
if(!global_circuitlist) { /* first one */
global_circuitlist = circ;
circ->next = NULL;
} else {
circ->next = global_circuitlist;
global_circuitlist = circ;
}
}
void circuit_remove(circuit_t *circ) {
circuit_t *tmpcirc;
assert(circ && global_circuitlist);
if(global_circuitlist == circ) {
global_circuitlist = global_circuitlist->next;
return;
}
for(tmpcirc = global_circuitlist;tmpcirc->next;tmpcirc = tmpcirc->next) {
if(tmpcirc->next == circ) {
tmpcirc->next = circ->next;
return;
}
}
}
void circuit_close_all_marked()
{
circuit_t *tmp,*m;
while (global_circuitlist && global_circuitlist->marked_for_close) {
tmp = global_circuitlist->next;
circuit_free(global_circuitlist);
global_circuitlist = tmp;
}
tmp = global_circuitlist;
while (tmp && tmp->next) {
if (tmp->next->marked_for_close) {
m = tmp->next->next;
circuit_free(tmp->next);
tmp->next = m;
/* Need to check new tmp->next; don't advance tmp. */
} else {
/* Advance tmp. */
tmp = tmp->next;
}
}
}
circuit_t *circuit_new(uint16_t p_circ_id, connection_t *p_conn) {
circuit_t *circ;
circ = tor_malloc_zero(sizeof(circuit_t));
circ->magic = CIRCUIT_MAGIC;
circ->timestamp_created = time(NULL);
circ->p_circ_id = p_circ_id;
circ->p_conn = p_conn;
circ->state = CIRCUIT_STATE_ONIONSKIN_PENDING;
/* CircIDs */
circ->p_circ_id = p_circ_id;
/* circ->n_circ_id remains 0 because we haven't identified the next hop yet */
circ->package_window = CIRCWINDOW_START;
circ->deliver_window = CIRCWINDOW_START;
circ->next_stream_id = crypto_pseudo_rand_int(1<<16);
circuit_add(circ);
return circ;
}
void circuit_free(circuit_t *circ) {
assert(circ);
assert(circ->magic == CIRCUIT_MAGIC);
if (circ->n_crypto)
crypto_free_cipher_env(circ->n_crypto);
if (circ->p_crypto)
crypto_free_cipher_env(circ->p_crypto);
if (circ->n_digest)
crypto_free_digest_env(circ->n_digest);
if (circ->p_digest)
crypto_free_digest_env(circ->p_digest);
if(circ->build_state)
tor_free(circ->build_state->chosen_exit);
tor_free(circ->build_state);
circuit_free_cpath(circ->cpath);
memset(circ, 0xAA, sizeof(circuit_t)); /* poison memory */
free(circ);
}
void circuit_free_cpath(crypt_path_t *cpath) {
crypt_path_t *victim, *head=cpath;
if(!cpath)
return;
/* it's a doubly linked list, so we have to notice when we've
* gone through it once. */
while(cpath->next && cpath->next != head) {
victim = cpath;
cpath = victim->next;
circuit_free_cpath_node(victim);
}
circuit_free_cpath_node(cpath);
}
static void circuit_free_cpath_node(crypt_path_t *victim) {
if(victim->f_crypto)
crypto_free_cipher_env(victim->f_crypto);
if(victim->b_crypto)
crypto_free_cipher_env(victim->b_crypto);
if(victim->f_digest)
crypto_free_digest_env(victim->f_digest);
if(victim->b_digest)
crypto_free_digest_env(victim->b_digest);
if(victim->handshake_state)
crypto_dh_free(victim->handshake_state);
free(victim);
}
/* return 0 if can't get a unique circ_id. */
static uint16_t get_unique_circ_id_by_conn(connection_t *conn, int circ_id_type) {
uint16_t test_circ_id;
int attempts=0;
uint16_t high_bit;
assert(conn && conn->type == CONN_TYPE_OR);
high_bit = (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_circ_id_conn(test_circ_id, conn));
return test_circ_id;
}
circuit_t *circuit_get_by_circ_id_conn(uint16_t circ_id, connection_t *conn) {
circuit_t *circ;
connection_t *tmpconn;
for(circ=global_circuitlist;circ;circ = circ->next) {
if (circ->marked_for_close)
continue;
if(circ->p_circ_id == circ_id) {
if(circ->p_conn == conn)
return circ;
for(tmpconn = circ->p_streams; tmpconn; tmpconn = tmpconn->next_stream) {
if(tmpconn == conn)
return circ;
}
}
if(circ->n_circ_id == circ_id) {
if(circ->n_conn == conn)
return circ;
for(tmpconn = circ->n_streams; tmpconn; tmpconn = tmpconn->next_stream) {
if(tmpconn == conn)
return circ;
}
}
}
return NULL;
}
circuit_t *circuit_get_by_conn(connection_t *conn) {
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)
return circ;
if(circ->n_conn == conn)
return circ;
for(tmpconn = circ->p_streams; tmpconn; tmpconn=tmpconn->next_stream)
if(tmpconn == conn)
return circ;
for(tmpconn = circ->n_streams; tmpconn; tmpconn=tmpconn->next_stream)
if(tmpconn == conn)
return circ;
}
return NULL;
}
/* Find the newest circ that conn can use, preferably one which is
* dirty. Circ must not be too old.
* If !conn, return newest.
*
* If must_be_open, ignore circs not in CIRCUIT_STATE_OPEN.
*/
circuit_t *circuit_get_newest(connection_t *conn, int must_be_open) {
circuit_t *circ, *newest=NULL, *leastdirty=NULL;
routerinfo_t *exitrouter;
for(circ=global_circuitlist;circ;circ = circ->next) {
if(!circ->cpath)
continue; /* this circ doesn't start at us */
if(must_be_open && (circ->state != CIRCUIT_STATE_OPEN || !circ->n_conn))
continue; /* ignore non-open circs */
if (circ->marked_for_close)
continue;
if(conn) {
if(circ->state == CIRCUIT_STATE_OPEN && circ->n_conn) /* open */
exitrouter = router_get_by_addr_port(circ->cpath->prev->addr, circ->cpath->prev->port);
else /* not open */
exitrouter = router_get_by_nickname(circ->build_state->chosen_exit);
if(!exitrouter || connection_ap_can_use_exit(conn, exitrouter) == ADDR_POLICY_REJECTED) {
/* can't exit from this router */
continue;
}
}
if(!newest || newest->timestamp_created < circ->timestamp_created) {
newest = circ;
}
if(conn && circ->timestamp_dirty &&
(!leastdirty || leastdirty->timestamp_dirty < circ->timestamp_dirty)) {
leastdirty = circ;
}
}
if(leastdirty &&
leastdirty->timestamp_dirty+options.NewCircuitPeriod > time(NULL)) {
/* log_fn(LOG_DEBUG,"Choosing in-use circuit %s:%d:%d.",
leastdirty->n_conn->address, leastdirty->n_port, leastdirty->n_circ_id); */
return leastdirty;
}
if(newest) {
/* log_fn(LOG_DEBUG,"Choosing circuit %s:%d:%d.",
newest->n_conn->address, newest->n_port, newest->n_circ_id); */
return newest;
}
return NULL;
}
#define MIN_SECONDS_BEFORE_EXPIRING_CIRC 10
/* circuits that were born at the end of their second might be expired
* after 10.1 seconds; circuits born at the beginning might be expired
* after closer to 11 seconds.
*/
/* close all circuits that start at us, aren't open, and were born
* at least MIN_SECONDS_BEFORE_EXPIRING_CIRC seconds ago */
void circuit_expire_building(void) {
int now = time(NULL);
circuit_t *victim, *circ = global_circuitlist;
while(circ) {
victim = circ;
circ = circ->next;
if(victim->cpath &&
victim->state != CIRCUIT_STATE_OPEN &&
victim->timestamp_created + MIN_SECONDS_BEFORE_EXPIRING_CIRC+1 < now &&
!victim->marked_for_close) {
if(victim->n_conn)
log_fn(LOG_INFO,"Abandoning circ %s:%d:%d (state %d:%s)",
victim->n_conn->address, victim->n_port, victim->n_circ_id,
victim->state, circuit_state_to_string[victim->state]);
else
log_fn(LOG_INFO,"Abandoning circ %d (state %d:%s)", victim->n_circ_id,
victim->state, circuit_state_to_string[victim->state]);
circuit_log_path(LOG_INFO,victim);
circuit_mark_for_close(victim);
}
}
}
/* count the number of circs starting at us that aren't open */
int circuit_count_building(void) {
circuit_t *circ;
int num=0;
for(circ=global_circuitlist;circ;circ = circ->next) {
if(circ->cpath
&& circ->state != CIRCUIT_STATE_OPEN
&& !circ->marked_for_close)
num++;
}
return num;
}
#define MIN_CIRCUITS_HANDLING_STREAM 2
/* return 1 if at least MIN_CIRCUITS_HANDLING_STREAM non-open circuits
* will have an acceptable exit node for conn. Else return 0.
*/
int circuit_stream_is_being_handled(connection_t *conn) {
circuit_t *circ;
routerinfo_t *exitrouter;
int num=0;
for(circ=global_circuitlist;circ;circ = circ->next) {
if(circ->cpath && circ->state != CIRCUIT_STATE_OPEN &&
!circ->marked_for_close) {
exitrouter = router_get_by_nickname(circ->build_state->chosen_exit);
if(exitrouter && connection_ap_can_use_exit(conn, exitrouter) != ADDR_POLICY_REJECTED)
if(++num >= MIN_CIRCUITS_HANDLING_STREAM)
return 1;
}
}
return 0;
}
/* update digest from the payload of cell. assign integrity part to cell. */
static void relay_set_digest(crypto_digest_env_t *digest, cell_t *cell) {
char integrity[4];
relay_header_t rh;
crypto_digest_add_bytes(digest, cell->payload, CELL_PAYLOAD_SIZE);
crypto_digest_get_digest(digest, integrity, 4);
// log_fn(LOG_DEBUG,"Putting digest of %u %u %u %u into relay cell.",
// integrity[0], integrity[1], integrity[2], integrity[3]);
relay_header_unpack(&rh, cell->payload);
memcpy(rh.integrity, integrity, 4);
relay_header_pack(cell->payload, &rh);
}
/* update digest from the payload of cell (with the integrity part set
* to 0). If the integrity part is valid return 1, else restore digest
* and cell to their original state and return 0.
*/
static int relay_digest_matches(crypto_digest_env_t *digest, cell_t *cell) {
char received_integrity[4], calculated_integrity[4];
relay_header_t rh;
crypto_digest_env_t *backup_digest=NULL;
backup_digest = crypto_digest_dup(digest);
relay_header_unpack(&rh, cell->payload);
memcpy(received_integrity, rh.integrity, 4);
memset(rh.integrity, 0, 4);
relay_header_pack(cell->payload, &rh);
// log_fn(LOG_DEBUG,"Reading digest of %u %u %u %u from relay cell.",
// received_integrity[0], received_integrity[1],
// received_integrity[2], received_integrity[3]);
crypto_digest_add_bytes(digest, cell->payload, CELL_PAYLOAD_SIZE);
crypto_digest_get_digest(digest, calculated_integrity, 4);
if(memcmp(received_integrity, calculated_integrity, 4)) {
// log_fn(LOG_INFO,"Recognized=0 but bad digest. Not recognizing.");
// (%d vs %d).", received_integrity, calculated_integrity);
/* restore digest to its old form */
crypto_digest_assign(digest, backup_digest);
/* restore the relay header */
memcpy(rh.integrity, received_integrity, 4);
relay_header_pack(cell->payload, &rh);
crypto_free_digest_env(backup_digest);
return 0;
}
crypto_free_digest_env(backup_digest);
return 1;
}
static int relay_crypt_one_payload(crypto_cipher_env_t *cipher, char *in,
int encrypt_mode) {
char out[CELL_PAYLOAD_SIZE]; /* 'in' must be this size too */
relay_header_t rh;
relay_header_unpack(&rh, in);
// log_fn(LOG_DEBUG,"before crypt: %d",rh.recognized);
if(( encrypt_mode && crypto_cipher_encrypt(cipher, in, CELL_PAYLOAD_SIZE, out)) ||
(!encrypt_mode && crypto_cipher_decrypt(cipher, in, CELL_PAYLOAD_SIZE, out))) {
log_fn(LOG_WARN,"Error during crypt: %s", crypto_perror());
return -1;
}
memcpy(in,out,CELL_PAYLOAD_SIZE);
relay_header_unpack(&rh, in);
// log_fn(LOG_DEBUG,"after crypt: %d",rh.recognized);
return 0;
}
/*
receive a relay cell:
- crypt it (encrypt APward, decrypt at AP, decrypt exitward)
- check if recognized (if exitward)
- if recognized, check digest, find right conn, deliver to edge.
- else connection_or_write_cell_to_buf to the right conn
*/
int circuit_receive_relay_cell(cell_t *cell, circuit_t *circ,
int cell_direction) {
connection_t *conn=NULL;
crypt_path_t *layer_hint=NULL;
char recognized=0;
assert(cell && circ);
assert(cell_direction == CELL_DIRECTION_OUT || cell_direction == CELL_DIRECTION_IN);
if (circ->marked_for_close)
return 0;
if(relay_crypt(circ, cell, cell_direction, &layer_hint, &recognized) < 0) {
log_fn(LOG_WARN,"relay crypt failed. Dropping connection.");
return -1;
}
if(recognized) {
conn = relay_lookup_conn(circ, cell, cell_direction);
if(cell_direction == CELL_DIRECTION_OUT) {
++stats_n_relay_cells_delivered;
log_fn(LOG_DEBUG,"Sending to exit.");
if (connection_edge_process_relay_cell(cell, circ, conn, EDGE_EXIT, NULL) < 0) {
log_fn(LOG_WARN,"connection_edge_process_relay_cell (at exit) failed.");
return -1;
}
}
if(cell_direction == CELL_DIRECTION_IN) {
++stats_n_relay_cells_delivered;
log_fn(LOG_DEBUG,"Sending to AP.");
if (connection_edge_process_relay_cell(cell, circ, conn, EDGE_AP, layer_hint) < 0) {
log_fn(LOG_WARN,"connection_edge_process_relay_cell (at AP) failed.");
return -1;
}
}
return 0;
}
/* not recognized. pass it on. */
if(cell_direction == CELL_DIRECTION_OUT) {
cell->circ_id = circ->n_circ_id; /* switch it */
conn = circ->n_conn;
} else {
cell->circ_id = circ->p_circ_id; /* switch it */
conn = circ->p_conn;
}
if(!conn) {
log_fn(LOG_WARN,"Didn't recognize cell, but circ stops here! Closing circ.");
return -1;
}
log_fn(LOG_DEBUG,"Passing on unrecognized cell.");
++stats_n_relay_cells_relayed;
connection_or_write_cell_to_buf(cell, conn);
return 0;
}
/* wrap this into receive_relay_cell one day */
static int relay_crypt(circuit_t *circ, cell_t *cell, int cell_direction,
crypt_path_t **layer_hint, char *recognized) {
crypt_path_t *thishop;
relay_header_t rh;
assert(circ && cell && recognized);
assert(cell_direction == CELL_DIRECTION_IN || cell_direction == CELL_DIRECTION_OUT);
if(cell_direction == CELL_DIRECTION_IN) {
if(circ->cpath) { /* we're at the beginning of the circuit.
We'll want to do layered crypts. */
thishop = circ->cpath;
if(thishop->state != CPATH_STATE_OPEN) {
log_fn(LOG_WARN,"Relay cell before first created cell? Closing.");
return -1;
}
do { /* Remember: cpath is in forward order, that is, first hop first. */
assert(thishop);
if(relay_crypt_one_payload(thishop->b_crypto, cell->payload, 0) < 0)
return -1;
relay_header_unpack(&rh, cell->payload);
if(rh.recognized == 0) {
/* it's possibly recognized. have to check digest to be sure. */
if(relay_digest_matches(thishop->b_digest, cell)) {
*recognized = 1;
*layer_hint = thishop;
return 0;
}
}
thishop = thishop->next;
} while(thishop != circ->cpath && thishop->state == CPATH_STATE_OPEN);
log_fn(LOG_WARN,"in-cell at OP not recognized. Closing.");
return -1;
} else { /* we're in the middle. Just one crypt. */
if(relay_crypt_one_payload(circ->p_crypto, cell->payload, 1) < 0)
return -1;
// log_fn(LOG_DEBUG,"Skipping recognized check, because we're not the OP.");
}
} else /* cell_direction == CELL_DIRECTION_OUT */ {
/* we're in the middle. Just one crypt. */
if(relay_crypt_one_payload(circ->n_crypto, cell->payload, 0) < 0)
return -1;
relay_header_unpack(&rh, cell->payload);
if (rh.recognized == 0) {
/* it's possibly recognized. have to check digest to be sure. */
if(relay_digest_matches(circ->n_digest, cell)) {
*recognized = 1;
return 0;
}
}
}
return 0;
}
/*
package a relay cell:
1) encrypt it to the right conn
2) connection_or_write_cell_to_buf to the right conn
*/
int
circuit_package_relay_cell(cell_t *cell, circuit_t *circ,
int cell_direction,
crypt_path_t *layer_hint)
{
connection_t *conn; /* where to send the cell */
crypt_path_t *thishop; /* counter for repeated crypts */
if(cell_direction == CELL_DIRECTION_OUT) {
conn = circ->n_conn;
if(!conn) {
log_fn(LOG_WARN,"outgoing relay cell has n_conn==NULL. Dropping.");
return 0; /* just drop it */
}
relay_set_digest(layer_hint->f_digest, cell);
thishop = layer_hint;
/* moving from farthest to nearest hop */
do {
assert(thishop);
log_fn(LOG_DEBUG,"crypting a layer of the relay cell.");
if(relay_crypt_one_payload(thishop->f_crypto, cell->payload, 1) < 0) {
return -1;
}
thishop = thishop->prev;
} while (thishop != circ->cpath->prev);
} else { /* incoming cell */
conn = circ->p_conn;
if(!conn) {
log_fn(LOG_WARN,"incoming relay cell has p_conn==NULL. Dropping.");
return 0; /* just drop it */
}
relay_set_digest(circ->p_digest, cell);
if(relay_crypt_one_payload(circ->p_crypto, cell->payload, 1) < 0)
return -1;
}
++stats_n_relay_cells_relayed;
connection_or_write_cell_to_buf(cell, conn);
return 0;
}
static connection_t *
relay_lookup_conn(circuit_t *circ, cell_t *cell, int cell_direction)
{
connection_t *tmpconn;
relay_header_t rh;
relay_header_unpack(&rh, cell->payload);
if(!rh.stream_id)
return NULL;
if(cell_direction == CELL_DIRECTION_OUT)
tmpconn = circ->n_streams;
else
tmpconn = circ->p_streams;
for( ; tmpconn; tmpconn=tmpconn->next_stream) {
if(rh.stream_id == tmpconn->stream_id) {
log_fn(LOG_DEBUG,"found conn for stream %d.", rh.stream_id);
return tmpconn;
}
// log_fn(LOG_DEBUG,"considered stream %d, not it.",tmpconn->stream_id);
}
return NULL; /* probably a begin relay cell */
}
void circuit_resume_edge_reading(circuit_t *circ, int edge_type, crypt_path_t *layer_hint) {
connection_t *conn;
assert(edge_type == EDGE_EXIT || edge_type == EDGE_AP);
log_fn(LOG_DEBUG,"resuming");
if(edge_type == EDGE_EXIT)
conn = circ->n_streams;
else
conn = circ->p_streams;
for( ; conn; conn=conn->next_stream) {
if((edge_type == EDGE_EXIT && conn->package_window > 0) ||
(edge_type == EDGE_AP && conn->package_window > 0 && conn->cpath_layer == layer_hint)) {
connection_start_reading(conn);
connection_edge_package_raw_inbuf(conn); /* handle whatever might still be on the inbuf */
/* If the circuit won't accept any more data, return without looking
* at any more of the streams. Any connections that should be stopped
* have already been stopped by connection_edge_package_raw_inbuf. */
if(circuit_consider_stop_edge_reading(circ, edge_type, layer_hint))
return;
}
}
}
/* returns 1 if the window is empty, else 0. If it's empty, tell edge conns to stop reading. */
int circuit_consider_stop_edge_reading(circuit_t *circ, int edge_type, crypt_path_t *layer_hint) {
connection_t *conn = NULL;
assert(edge_type == EDGE_EXIT || edge_type == EDGE_AP);
assert(edge_type == EDGE_EXIT || layer_hint);
log_fn(LOG_DEBUG,"considering");
if(edge_type == EDGE_EXIT && circ->package_window <= 0)
conn = circ->n_streams;
else if(edge_type == EDGE_AP && layer_hint->package_window <= 0)
conn = circ->p_streams;
else
return 0;
for( ; conn; conn=conn->next_stream)
if(!layer_hint || conn->cpath_layer == layer_hint)
connection_stop_reading(conn);
log_fn(LOG_DEBUG,"yes. stopped.");
return 1;
}
void circuit_consider_sending_sendme(circuit_t *circ, int edge_type, crypt_path_t *layer_hint) {
while((edge_type == EDGE_AP ? layer_hint->deliver_window : circ->deliver_window) <
CIRCWINDOW_START - CIRCWINDOW_INCREMENT) {
log_fn(LOG_DEBUG,"Queueing circuit sendme.");
if(edge_type == EDGE_AP)
layer_hint->deliver_window += CIRCWINDOW_INCREMENT;
else
circ->deliver_window += CIRCWINDOW_INCREMENT;
if(connection_edge_send_command(NULL, circ, RELAY_COMMAND_SENDME,
NULL, 0, layer_hint) < 0) {
log_fn(LOG_WARN,"connection_edge_send_command failed. Circuit's closed.");
return; /* the circuit's closed, don't continue */
}
}
}
int _circuit_mark_for_close(circuit_t *circ) {
connection_t *conn;
assert_circuit_ok(circ);
if (circ->marked_for_close < 0)
return -1;
if(circ->state == CIRCUIT_STATE_ONIONSKIN_PENDING) {
onion_pending_remove(circ);
}
if(circ->n_conn)
connection_send_destroy(circ->n_circ_id, circ->n_conn);
for(conn=circ->n_streams; conn; conn=conn->next_stream) {
connection_edge_destroy(circ->n_circ_id, conn);
}
if(circ->p_conn)
connection_send_destroy(circ->n_circ_id, circ->p_conn);
for(conn=circ->p_streams; conn; conn=conn->next_stream) {
connection_edge_destroy(circ->p_circ_id, conn);
}
if (circ->state == CIRCUIT_STATE_BUILDING ||
circ->state == CIRCUIT_STATE_OR_WAIT) {
/* If we never built the circuit, note it as a failure. */
/* Note that we can't just check circ->cpath here, because if
* circuit-building failed immediately, it won't be set yet. */
circuit_increment_failure_count();
}
circ->marked_for_close = 1;
return 0;
}
void circuit_detach_stream(circuit_t *circ, connection_t *conn) {
connection_t *prevconn;
assert(circ);
assert(conn);
if(conn == circ->p_streams) {
circ->p_streams = conn->next_stream;
return;
}
if(conn == circ->n_streams) {
circ->n_streams = conn->next_stream;
return;
}
for(prevconn = circ->p_streams; prevconn && prevconn->next_stream && prevconn->next_stream != conn; prevconn = prevconn->next_stream) ;
if(prevconn && prevconn->next_stream) {
prevconn->next_stream = conn->next_stream;
return;
}
for(prevconn = circ->n_streams; prevconn && prevconn->next_stream && prevconn->next_stream != conn; prevconn = prevconn->next_stream) ;
if(prevconn && prevconn->next_stream) {
prevconn->next_stream = conn->next_stream;
return;
}
log_fn(LOG_ERR,"edge conn not in circuit's list?");
assert(0); /* should never get here */
}
void circuit_about_to_close_connection(connection_t *conn) {
/* send destroys for all circuits using conn */
/* currently, we assume it's too late to flush conn's buf here.
* down the road, maybe we'll consider that eof doesn't mean can't-write
*/
circuit_t *circ;
switch(conn->type) {
case CONN_TYPE_OR:
/* We must close all the circuits on it. */
while((circ = circuit_get_by_conn(conn))) {
if(circ->n_conn == conn) /* it's closing in front of us */
circ->n_conn = NULL;
if(circ->p_conn == conn) /* it's closing behind us */
circ->p_conn = NULL;
circuit_mark_for_close(circ);
}
return;
case CONN_TYPE_AP:
case CONN_TYPE_EXIT:
/* It's an edge conn. Need to remove it from the linked list of
* conn's for this circuit. Confirm that 'end' relay command has
* been sent. But don't kill the circuit.
*/
circ = circuit_get_by_conn(conn);
if(!circ)
return;
if(!conn->has_sent_end) {
log_fn(LOG_WARN,"Edge connection hasn't sent end yet? Bug.");
connection_mark_for_close(conn, END_STREAM_REASON_MISC);
}
circuit_detach_stream(circ, conn);
} /* end switch */
}
void circuit_log_path(int severity, circuit_t *circ) {
char buf[1024];
char *s = buf;
struct crypt_path_t *hop;
char *states[] = {"closed", "waiting for keys", "open"};
routerinfo_t *router;
assert(circ->cpath);
snprintf(s, sizeof(buf)-1, "circ (length %d, exit %s): ",
circ->build_state->desired_path_len, circ->build_state->chosen_exit);
hop=circ->cpath;
do {
s = buf + strlen(buf);
router = router_get_by_addr_port(hop->addr,hop->port);
if(router) {
snprintf(s, sizeof(buf) - (s - buf), "%s(%s) ",
router->nickname, states[hop->state]);
} else {
snprintf(s, sizeof(buf) - (s - buf), "UNKNOWN ");
}
hop=hop->next;
} while(hop!=circ->cpath);
log_fn(severity,"%s",buf);
}
static void
circuit_dump_details(int severity, circuit_t *circ, int poll_index,
char *type, int this_circid, int other_circid) {
struct crypt_path_t *hop;
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(circ->cpath) { /* circ starts at this node */
if(circ->state == CIRCUIT_STATE_BUILDING)
log(severity,"Building: desired len %d, planned exit node %s.",
circ->build_state->desired_path_len, circ->build_state->chosen_exit);
for(hop=circ->cpath;hop->next != circ->cpath; hop=hop->next)
log(severity,"hop: state %d, addr %x, port %d", hop->state,
(unsigned int)hop->addr,
(int)hop->port);
}
}
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->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);
}
}
}
}
void circuit_expire_unused_circuits(void) {
circuit_t *circ, *tmpcirc;
time_t now = time(NULL);
circ = global_circuitlist;
while(circ) {
tmpcirc = circ;
circ = circ->next;
if(tmpcirc->timestamp_dirty &&
tmpcirc->timestamp_dirty + options.NewCircuitPeriod < now &&
!tmpcirc->p_conn && !tmpcirc->p_streams && !tmpcirc->marked_for_close) {
log_fn(LOG_DEBUG,"Closing n_circ_id %d",tmpcirc->n_circ_id);
circuit_mark_for_close(tmpcirc);
}
}
}
/* Number of consecutive failures so far; should only be touched by
* circuit_launch_new and circuit_*_failure_count.
*/
static int n_circuit_failures = 0;
/* Return -1 if you aren't going to try to make a circuit, 0 if you did try. */
int circuit_launch_new(void) {
if(!options.SocksPort) /* we're not an application proxy. no need for circuits. */
return -1;
if(n_circuit_failures > 5) { /* too many failed circs in a row. don't try. */
// log_fn(LOG_INFO,"%d failures so far, not trying.",n_circuit_failures);
return -1;
}
/* try a circ. if it fails, circuit_mark_for_close will increment n_circuit_failures */
circuit_establish_circuit();
return 0;
}
void circuit_increment_failure_count(void) {
++n_circuit_failures;
log_fn(LOG_DEBUG,"n_circuit_failures now %d.",n_circuit_failures);
}
void circuit_reset_failure_count(void) {
n_circuit_failures = 0;
}
int circuit_establish_circuit(void) {
routerinfo_t *firsthop;
connection_t *n_conn;
circuit_t *circ;
circ = circuit_new(0, NULL); /* sets circ->p_circ_id and circ->p_conn */
circ->state = CIRCUIT_STATE_OR_WAIT;
circ->build_state = onion_new_cpath_build_state();
if (! circ->build_state) {
log_fn(LOG_INFO,"Generating cpath length failed.");
circuit_mark_for_close(circ);
return -1;
}
onion_extend_cpath(&circ->cpath, circ->build_state, &firsthop);
if(!circ->cpath) {
log_fn(LOG_INFO,"Generating first cpath hop failed.");
circuit_mark_for_close(circ);
return -1;
}
/* now see if we're already connected to the first OR in 'route' */
log_fn(LOG_DEBUG,"Looking for firsthop '%s:%u'",
firsthop->address,firsthop->or_port);
n_conn = connection_twin_get_by_addr_port(firsthop->addr,firsthop->or_port);
if(!n_conn || n_conn->state != OR_CONN_STATE_OPEN) { /* not currently connected */
circ->n_addr = firsthop->addr;
circ->n_port = firsthop->or_port;
if(options.ORPort) { /* we would be connected if he were up. and he's not. */
log_fn(LOG_INFO,"Route's firsthop isn't connected.");
circuit_mark_for_close(circ);
return -1;
}
if(!n_conn) { /* launch the connection */
n_conn = connection_or_connect(firsthop);
if(!n_conn) { /* connect failed, forget the whole thing */
log_fn(LOG_INFO,"connect to firsthop failed. Closing.");
circuit_mark_for_close(circ);
return -1;
}
}
log_fn(LOG_DEBUG,"connecting in progress (or finished). Good.");
return 0; /* return success. The onion/circuit/etc will be taken care of automatically
* (may already have been) whenever n_conn reaches OR_CONN_STATE_OPEN.
*/
} else { /* it (or a twin) is 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.");
circuit_mark_for_close(circ);
return -1;
}
}
return 0;
}
/* find circuits that are waiting on me, if any, and get them to send the onion */
void circuit_n_conn_open(connection_t *or_conn) {
circuit_t *circ;
for(circ=global_circuitlist;circ;circ = circ->next) {
if (circ->marked_for_close)
continue;
if(circ->cpath && circ->n_addr == or_conn->addr && circ->n_port == or_conn->port) {
assert(circ->state == CIRCUIT_STATE_OR_WAIT);
log_fn(LOG_DEBUG,"Found circ %d, sending onion skin.", circ->n_circ_id);
circ->n_conn = or_conn;
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? */
}
}
}
}
int circuit_send_next_onion_skin(circuit_t *circ) {
cell_t cell;
crypt_path_t *hop;
routerinfo_t *router;
int r;
int circ_id_type;
char payload[6+ONIONSKIN_CHALLENGE_LEN];
assert(circ && circ->cpath);
if(circ->cpath->state == CPATH_STATE_CLOSED) {
assert(circ->n_conn && circ->n_conn->type == CONN_TYPE_OR);
log_fn(LOG_DEBUG,"First skin; sending create cell.");
circ_id_type = decide_circ_id_type(options.Nickname,
circ->n_conn->nickname);
circ->n_circ_id = get_unique_circ_id_by_conn(circ->n_conn, circ_id_type);
memset(&cell, 0, sizeof(cell_t));
cell.command = CELL_CREATE;
cell.circ_id = circ->n_circ_id;
if(onion_skin_create(circ->n_conn->onion_pkey, &(circ->cpath->handshake_state), cell.payload) < 0) {
log_fn(LOG_WARN,"onion_skin_create (first hop) failed.");
return -1;
}
connection_or_write_cell_to_buf(&cell, circ->n_conn);
circ->cpath->state = CPATH_STATE_AWAITING_KEYS;
circ->state = CIRCUIT_STATE_BUILDING;
log_fn(LOG_DEBUG,"first skin; finished sending create cell.");
} else {
assert(circ->cpath->state == CPATH_STATE_OPEN);
assert(circ->state == CIRCUIT_STATE_BUILDING);
log_fn(LOG_DEBUG,"starting to send subsequent skin.");
r = onion_extend_cpath(&circ->cpath, circ->build_state, &router);
if (r==1) {
/* done building the circuit. whew. */
circ->state = CIRCUIT_STATE_OPEN;
log_fn(LOG_INFO,"circuit built!");
circuit_reset_failure_count();
/* Tell any AP connections that have been waiting for a new
* circuit that one is ready. */
connection_ap_attach_pending();
return 0;
} else if (r<0) {
log_fn(LOG_INFO,"Unable to extend circuit path.");
return -1;
}
hop = circ->cpath->prev;
*(uint32_t*)payload = htonl(hop->addr);
*(uint16_t*)(payload+4) = htons(hop->port);
if(onion_skin_create(router->onion_pkey, &(hop->handshake_state), payload+6) < 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, sizeof(payload), hop->prev) < 0)
return 0; /* circuit is closed */
hop->state = CPATH_STATE_AWAITING_KEYS;
}
return 0;
}
/* 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;
int circ_id_type;
cell_t newcell;
if(circ->n_conn) {
log_fn(LOG_WARN,"n_conn already set. Bug/attack. Closing.");
return -1;
}
circ->n_addr = ntohl(*(uint32_t*)(cell->payload+RELAY_HEADER_SIZE));
circ->n_port = ntohs(*(uint16_t*)(cell->payload+RELAY_HEADER_SIZE+4));
n_conn = connection_twin_get_by_addr_port(circ->n_addr,circ->n_port);
if(!n_conn || n_conn->type != CONN_TYPE_OR) {
/* I've disabled making connections through OPs, but it's definitely
* possible here. I'm not sure if it would be a bug or a feature.
*
* Note also 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;
in.s_addr = htonl(circ->n_addr);
log_fn(LOG_INFO,"Next router (%s:%d) not connected. Closing.", inet_ntoa(in), circ->n_port);
connection_edge_send_command(NULL, circ, RELAY_COMMAND_TRUNCATED,
NULL, 0, NULL);
return 0;
}
circ->n_addr = n_conn->addr; /* these are different if we found a twin instead */
circ->n_port = n_conn->port;
circ->n_conn = n_conn;
log_fn(LOG_DEBUG,"n_conn is %s:%u",n_conn->address,n_conn->port);
circ_id_type = decide_circ_id_type(options.Nickname, n_conn->nickname);
// log_fn(LOG_DEBUG,"circ_id_type = %u.",circ_id_type);
circ->n_circ_id = get_unique_circ_id_by_conn(circ->n_conn, circ_id_type);
if(!circ->n_circ_id) {
log_fn(LOG_WARN,"failed to get unique circID.");
return -1;
}
log_fn(LOG_DEBUG,"Chosen circID %u.",circ->n_circ_id);
memset(&newcell, 0, sizeof(cell_t));
newcell.command = CELL_CREATE;
newcell.circ_id = circ->n_circ_id;
memcpy(newcell.payload, cell->payload+RELAY_HEADER_SIZE+6,
ONIONSKIN_CHALLENGE_LEN);
connection_or_write_cell_to_buf(&newcell, circ->n_conn);
return 0;
}
extern int has_completed_circuit;
int circuit_finish_handshake(circuit_t *circ, char *reply) {
unsigned char iv[16];
unsigned char keys[40+32];
crypt_path_t *hop;
memset(iv, 0, 16);
assert(circ->cpath);
if(circ->cpath->state == CPATH_STATE_AWAITING_KEYS)
hop = circ->cpath;
else {
for(hop=circ->cpath->next;
hop != circ->cpath && hop->state == CPATH_STATE_OPEN;
hop=hop->next) ;
if(hop == circ->cpath) { /* got an extended when we're all done? */
log_fn(LOG_WARN,"got extended when circ already built? Closing.");
return -1;
}
}
assert(hop->state == CPATH_STATE_AWAITING_KEYS);
if(onion_skin_client_handshake(hop->handshake_state, reply, keys, 40+32) < 0) {
log_fn(LOG_WARN,"onion_skin_client_handshake failed.");
return -1;
}
crypto_dh_free(hop->handshake_state); /* don't need it anymore */
hop->handshake_state = NULL;
log_fn(LOG_DEBUG,"hop init digest forward %u, backward %u.",
(unsigned)*(uint32_t*)keys, (unsigned)*(uint32_t*)(keys+20));
hop->f_digest = crypto_new_digest_env(CRYPTO_SHA1_DIGEST);
crypto_digest_add_bytes(hop->f_digest, keys, 20);
hop->b_digest = crypto_new_digest_env(CRYPTO_SHA1_DIGEST);
crypto_digest_add_bytes(hop->b_digest, keys+20, 20);
log_fn(LOG_DEBUG,"hop init cipher forward %u, backward %u.",
(unsigned)*(uint32_t*)(keys+40), (unsigned) *(uint32_t*)(keys+40+16));
if (!(hop->f_crypto =
crypto_create_init_cipher(CIRCUIT_CIPHER,keys+40,iv,1))) {
log(LOG_WARN,"forward cipher initialization failed.");
return -1;
}
if (!(hop->b_crypto =
crypto_create_init_cipher(CIRCUIT_CIPHER,keys+40+16,iv,0))) {
log(LOG_WARN,"backward cipher initialization failed.");
return -1;
}
hop->state = CPATH_STATE_OPEN;
log_fn(LOG_INFO,"finished");
if(!has_completed_circuit) {
has_completed_circuit=1;
log_fn(LOG_WARN,"Tor has successfully opened a circuit. Looks like it's working.");
}
circuit_log_path(LOG_INFO,circ);
return 0;
}
int circuit_truncated(circuit_t *circ, crypt_path_t *layer) {
crypt_path_t *victim;
connection_t *stream;
assert(circ);
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;
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_for_close(stream,0);
}
}
layer->next = victim->next;
circuit_free_cpath_node(victim);
}
log_fn(LOG_INFO, "finished");
return 0;
}
void assert_cpath_layer_ok(const crypt_path_t *cp)
{
assert(cp->f_crypto);
assert(cp->b_crypto);
assert(cp->addr);
assert(cp->port);
switch(cp->state)
{
case CPATH_STATE_CLOSED:
case CPATH_STATE_OPEN:
assert(!cp->handshake_state);
break;
case CPATH_STATE_AWAITING_KEYS:
assert(cp->handshake_state);
break;
default:
assert(0);
}
assert(cp->package_window >= 0);
assert(cp->deliver_window >= 0);
}
void assert_cpath_ok(const crypt_path_t *cp)
{
while(cp->prev)
cp = cp->prev;
while(cp->next) {
assert_cpath_layer_ok(cp);
/* layers must be in sequence of: "open* awaiting? closed*" */
if (cp->prev) {
if (cp->prev->state == CPATH_STATE_OPEN) {
assert(cp->state == CPATH_STATE_CLOSED ||
cp->state == CPATH_STATE_AWAITING_KEYS);
} else {
assert(cp->state == CPATH_STATE_CLOSED);
}
}
cp = cp->next;
}
}
void assert_circuit_ok(const circuit_t *c)
{
connection_t *conn;
assert(c);
assert(c->magic == CIRCUIT_MAGIC);
if (c->n_conn)
assert(c->n_conn->type == CONN_TYPE_OR);
if (c->p_conn)
assert(c->p_conn->type == CONN_TYPE_OR);
for (conn = c->p_streams; conn; conn = conn->next_stream)
assert(conn->type == CONN_TYPE_AP);
for (conn = c->n_streams; conn; conn = conn->next_stream)
assert(conn->type == CONN_TYPE_EXIT);
assert(c->deliver_window >= 0);
assert(c->package_window >= 0);
if (c->state == CIRCUIT_STATE_OPEN) {
if (c->cpath) {
assert(!c->n_crypto);
assert(!c->p_crypto);
assert(!c->n_digest);
assert(!c->p_digest);
} else {
assert(c->n_crypto);
assert(c->p_crypto);
assert(c->n_digest);
assert(c->p_digest);
}
}
if (c->cpath) {
//XXX assert_cpath_ok(c->cpath);
}
}
/*
Local Variables:
mode:c
indent-tabs-mode:nil
c-basic-offset:2
End:
*/
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