diff options
| -rw-r--r-- | doc/tor-spec.txt | 20 | ||||
| -rw-r--r-- | src/or/circuitbuild.c | 29 | ||||
| -rw-r--r-- | src/or/command.c | 16 | ||||
| -rw-r--r-- | src/or/connection_or.c | 11 | ||||
| -rw-r--r-- | src/or/or.h | 9 |
5 files changed, 48 insertions, 37 deletions
diff --git a/doc/tor-spec.txt b/doc/tor-spec.txt index 95e724287..7efcc87a7 100644 --- a/doc/tor-spec.txt +++ b/doc/tor-spec.txt @@ -198,13 +198,19 @@ TODO: (very soon) DH data (g^y) [128 bytes] Derivative key data (KH) [20 bytes] <see 4.2 below> - The CircID for a CREATE cell is an arbitrarily chosen 2-byte - integer, selected by the node (OP or OR) that sends the CREATE - cell. To prevent CircID collisions, when one OR sends a CREATE - cell to another, it chooses from only one half of the possible - values based on the ORs' nicknames: if the sending OR has a - lexicographically earlier nickname, it chooses a CircID with a high - bit of 0; otherwise, it chooses a CircID with a high bit of 1. + The CircID for a CREATE cell is an arbitrarily chosen 2-byte integer, + selected by the node (OP or OR) that sends the CREATE cell. To prevent + CircID collisions, when one OR sends a CREATE cell to another, it chooses + from only one half of the possible values based on the ORs' public + identity keys: if the sending OR has a lower key, it chooses a CircID with + an MSB of 0; otherwise, it chooses a CircID with an MSB of 1. + + Public keys are compared numerically by modulus. + + (Older versions of Tor compared OR nicknames, and did it in a broken and + unreliable way. To support versions of Tor earlier than 0.0.9pre6, + implementations should notice when the other side of a connection is + sending CREATE cells with the "wrong" MSG, and switch accordingly.) 4.2. Setting circuit keys diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c index 12b109ced..0bd8c01f5 100644 --- a/src/or/circuitbuild.c +++ b/src/or/circuitbuild.c @@ -35,14 +35,14 @@ static int count_acceptable_routers(smartlist_t *routers); * * Return it, or 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) { +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 = (circ_id_type == CIRC_ID_TYPE_HIGHER) ? 1<<15 : 0; + high_bit = (conn->circ_id_type == CIRC_ID_TYPE_HIGHER) ? 1<<15 : 0; do { /* Sequentially iterate over test_circ_id=1...1<<15-1 until we find a * circID such that (high_bit|test_circ_id) is not already used. */ @@ -359,9 +359,7 @@ circuit_deliver_create_cell(circuit_t *circ, char *payload) { * Solution: switch to identity-based comparison, but if we get * any circuits in the wrong half of the space, switch. */ - circ_id_type = decide_circ_id_type(get_options()->Nickname, - circ->n_conn->nickname); - circ->n_circ_id = get_unique_circ_id_by_conn(circ->n_conn, circ_id_type); + circ->n_circ_id = get_unique_circ_id_by_conn(circ->n_conn); if(!circ->n_circ_id) { log_fn(LOG_WARN,"failed to get unique circID."); return -1; @@ -697,27 +695,6 @@ int circuit_truncated(circuit_t *circ, crypt_path_t *layer) { #endif } -/** Decide whether the first bit of the circuit ID will be - * 0 or 1, to avoid conflicts where each side randomly chooses - * the same circuit ID. - * - * Return CIRC_ID_TYPE_LOWER if local_nick is NULL, or if - * local_nick is lexographically smaller than remote_nick. - * Else return CIRC_ID_TYPE_HIGHER. - */ -static int decide_circ_id_type(char *local_nick, char *remote_nick) { - int result; - - tor_assert(remote_nick); - if(!local_nick) - return CIRC_ID_TYPE_LOWER; - result = strcasecmp(local_nick, remote_nick); - tor_assert(result); - if(result < 0) - return CIRC_ID_TYPE_LOWER; - return CIRC_ID_TYPE_HIGHER; -} - /** Given a response payload and keys, initialize, then send a created * cell back. */ diff --git a/src/or/command.c b/src/or/command.c index 5cc28b8d1..021e12a4f 100644 --- a/src/or/command.c +++ b/src/or/command.c @@ -139,6 +139,22 @@ static void command_process_create_cell(cell_t *cell, connection_t *conn) { return; } + /* If the high bit of the circuit ID is not as expected, then switch + * which half of the space we'll use for our own CREATE cells. + * + * This can happen because Tor 0.0.9pre5 and earlier decide which + * half to use based on nickname, and we now use identity keys. + */ + if ((cell->circ_id & (1<<15)) && conn->circ_id_type == CIRC_ID_TYPE_HIGHER) { + log_fn(LOG_INFO, "Got a high circuit ID from %s (%d); switching to low circuit IDs.", + conn->nickname, conn->s); + conn->circ_id_type = CIRC_ID_TYPE_LOWER; + } else if (!(cell->circ_id & (1<<15)) && conn->circ_id_type == CIRC_ID_TYPE_LOWER) { + log_fn(LOG_INFO, "Got a low circuit ID from %s (%d); switching to high circuit IDs.", + conn->nickname, conn->s); + conn->circ_id_type = CIRC_ID_TYPE_HIGHER; + } + circ = circuit_new(cell->circ_id, conn); circ->state = CIRCUIT_STATE_ONIONSKIN_PENDING; circ->purpose = CIRCUIT_PURPOSE_OR; diff --git a/src/or/connection_or.c b/src/or/connection_or.c index 98dc8803b..1b419e557 100644 --- a/src/or/connection_or.c +++ b/src/or/connection_or.c @@ -339,7 +339,7 @@ connection_tls_finish_handshake(connection_t *conn) { conn->state = OR_CONN_STATE_OPEN; connection_watch_events(conn, POLLIN); log_fn(LOG_DEBUG,"tls handshake done. verifying."); - if (! tor_tls_peer_has_cert(conn->tls)) { /* It's an OP. */ + if (! tor_tls_peer_has_cert(conn->tls)) { /* It's an old OP. */ if (server_mode(options)) { /* I'm an OR; good. */ conn->receiver_bucket = conn->bandwidth = DEFAULT_BANDWIDTH_OP; return 0; @@ -348,7 +348,7 @@ connection_tls_finish_handshake(connection_t *conn) { return -1; } } - /* Okay; the other side is an OR. */ + /* Okay; the other side is an OR or a post-0.0.8 OP (with a cert). */ if (tor_tls_get_peer_cert_nickname(conn->tls, nickname, MAX_NICKNAME_LEN)) { log_fn(LOG_WARN,"Other side (%s:%d) has a cert without a valid nickname. Closing.", conn->address, conn->port); @@ -366,6 +366,12 @@ connection_tls_finish_handshake(connection_t *conn) { crypto_pk_get_digest(identity_rcvd, digest_rcvd); crypto_free_pk_env(identity_rcvd); + if (crypto_pk_cmp_keys(get_identity_key(), identity_rcvd)<0) { + conn->circ_id_type = CIRC_ID_TYPE_LOWER; + } else { + conn->circ_id_type = CIRC_ID_TYPE_HIGHER; + } + router = router_get_by_nickname(nickname); if(router && /* we know this nickname */ router->is_verified && /* make sure it's the right guy */ @@ -394,6 +400,7 @@ connection_tls_finish_handshake(connection_t *conn) { if (!server_mode(options)) { /* If I'm an OP... */ conn->receiver_bucket = conn->bandwidth = DEFAULT_BANDWIDTH_OP; } + directory_set_dirty(); circuit_n_conn_done(conn, 1); /* send the pending creates, if any. */ /* Note the success */ diff --git a/src/or/or.h b/src/or/or.h index f8eb0ab94..b5cb1b639 100644 --- a/src/or/or.h +++ b/src/or/or.h @@ -150,8 +150,10 @@ * In seconds. */ #define ROUTER_MAX_AGE (60*60*24) -#define CIRC_ID_TYPE_LOWER 0 -#define CIRC_ID_TYPE_HIGHER 1 +typedef enum { + CIRC_ID_TYPE_LOWER=0, + CIRC_ID_TYPE_HIGHER=1 +} circ_id_type_t; #define _CONN_TYPE_MIN 3 /** Type for sockets listening for OR connections. */ @@ -534,6 +536,9 @@ struct connection_t { * add 'bandwidth' to this, capping it at 10*bandwidth. * (OPEN ORs only) */ + circ_id_type_t circ_id_type; /**< When we send CREATE cells along this + * connection, which half of the space should + * we use? */ /* Used only by DIR and AP connections: */ char rend_query[REND_SERVICE_ID_LEN+1]; /**< What rendezvous service are we |