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Cell types and states for new OR handshake

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Also, define all commands > 128 as variable-length when using
v3 or later link protocol.  Running into a var cell with an
unrecognized type is no longer a bug.
This commit is contained in:
Nick Mathewson 2011-09-13 10:03:09 -04:00
parent fdbb9cdf74
commit 1b0645acba
5 changed files with 61 additions and 35 deletions
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38
src/or/buffers.c
View File

@ -1005,6 +1005,32 @@ fetch_from_buf(char *string, size_t string_len, buf_t *buf)
return (int)buf->datalen;
}
/** True iff the cell command <b>command</b> is one that implies a variable-length
* cell in Tor link protocol <b>linkproto</b>. */
static inline int
cell_command_is_var_length(uint8_t command, int linkproto)
{
/* If linkproto is v2 (2), CELL_VERSIONS is the only variable-length cells work as
* implemented here. If it's 1, there are no variable-length cells. Tor
* does not support other versions right now, and so can't negotiate them.
*/
switch (linkproto) {
case 1:
/* Link protocol version 1 has no variable-length cells. */
return 0;
case 2:
/* In link protocol version 2, VERSIONS is the only variable-length cell */
return command == CELL_VERSIONS;
case 0:
case 3:
default:
/* In link protocol version 3 and later, and in version "unknown",
* commands 128 and higher indicate variable-length. VERSIONS is
* grandfathered in. */
return command == CELL_VERSIONS || command >= 128;
}
}
/** Check <b>buf</b> for a variable-length cell according to the rules of link
* protocol version <b>linkproto</b>. If one is found, pull it off the buffer
* and assign a newly allocated var_cell_t to *<b>out</b>, and return 1.
@ -1019,12 +1045,6 @@ fetch_var_cell_from_buf(buf_t *buf, var_cell_t **out, int linkproto)
var_cell_t *result;
uint8_t command;
uint16_t length;
/* If linkproto is unknown (0) or v2 (2), variable-length cells work as
* implemented here. If it's 1, there are no variable-length cells. Tor
* does not support other versions right now, and so can't negotiate them.
*/
if (linkproto == 1)
return 0;
check();
*out = NULL;
if (buf->datalen < VAR_CELL_HEADER_SIZE)
@ -1032,7 +1052,7 @@ fetch_var_cell_from_buf(buf_t *buf, var_cell_t **out, int linkproto)
peek_from_buf(hdr, sizeof(hdr), buf);
command = get_uint8(hdr+2);
if (!(CELL_COMMAND_IS_VAR_LENGTH(command)))
if (!(cell_command_is_var_length(command, linkproto)))
return 0;
length = ntohs(get_uint16(hdr+3));
@ -1101,8 +1121,6 @@ fetch_var_cell_from_evbuffer(struct evbuffer *buf, var_cell_t **out,
uint16_t cell_length;
var_cell_t *cell;
int result = 0;
if (linkproto == 1)
return 0;
*out = NULL;
buf_len = evbuffer_get_length(buf);
@ -1113,7 +1131,7 @@ fetch_var_cell_from_evbuffer(struct evbuffer *buf, var_cell_t **out,
tor_assert(n >= VAR_CELL_HEADER_SIZE);
command = get_uint8(hdr+2);
if (!(CELL_COMMAND_IS_VAR_LENGTH(command))) {
if (!(cell_command_is_var_length(command, linkproto))) {
goto done;
}

11
src/or/command.c
View File

@ -93,7 +93,7 @@ command_time_process_cell(cell_t *cell, or_connection_t *conn, int *time,
void
command_process_cell(cell_t *cell, or_connection_t *conn)
{
int handshaking = (conn->_base.state == OR_CONN_STATE_OR_HANDSHAKING);
int handshaking = (conn->_base.state == OR_CONN_STATE_OR_HANDSHAKING_V2);
#ifdef KEEP_TIMING_STATS
/* how many of each cell have we seen so far this second? needs better
* name. */
@ -207,7 +207,7 @@ command_process_var_cell(var_cell_t *cell, or_connection_t *conn)
#endif
/* reject all when not handshaking. */
if (conn->_base.state != OR_CONN_STATE_OR_HANDSHAKING)
if (conn->_base.state != OR_CONN_STATE_OR_HANDSHAKING_V2)
return;
switch (cell->command) {
@ -216,10 +216,9 @@ command_process_var_cell(var_cell_t *cell, or_connection_t *conn)
PROCESS_CELL(versions, cell, conn);
break;
default:
log_warn(LD_BUG,
log_fn(LOG_INFO, LD_PROTOCOL,
"Variable-length cell of unknown type (%d) received.",
cell->command);
tor_fragile_assert();
break;
}
}
@ -506,7 +505,7 @@ command_process_versions_cell(var_cell_t *cell, or_connection_t *conn)
int highest_supported_version = 0;
const uint8_t *cp, *end;
if (conn->link_proto != 0 ||
conn->_base.state != OR_CONN_STATE_OR_HANDSHAKING ||
conn->_base.state != OR_CONN_STATE_OR_HANDSHAKING_V2 ||
(conn->handshake_state && conn->handshake_state->received_versions)) {
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"Received a VERSIONS cell on a connection with its version "
@ -572,7 +571,7 @@ command_process_netinfo_cell(cell_t *cell, or_connection_t *conn)
conn->link_proto == 0 ? "non-versioned" : "a v1");
return;
}
if (conn->_base.state != OR_CONN_STATE_OR_HANDSHAKING) {
if (conn->_base.state != OR_CONN_STATE_OR_HANDSHAKING_V2) {
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"Received a NETINFO cell on non-handshaking connection; dropping.");
return;

9
src/or/connection.c
View File

@ -140,10 +140,13 @@ conn_state_to_string(int type, int state)
case OR_CONN_STATE_PROXY_HANDSHAKING: return "handshaking (proxy)";
case OR_CONN_STATE_TLS_HANDSHAKING: return "handshaking (TLS)";
case OR_CONN_STATE_TLS_CLIENT_RENEGOTIATING:
return "renegotiating (TLS)";
return "renegotiating (TLS, v2 handshake)";
case OR_CONN_STATE_TLS_SERVER_RENEGOTIATING:
return "waiting for renegotiation (TLS)";
case OR_CONN_STATE_OR_HANDSHAKING: return "handshaking (Tor)";
return "waiting for renegotiation or V3 handshake";
case OR_CONN_STATE_OR_HANDSHAKING_V2:
return "handshaking (Tor, v2 handshake)";
case OR_CONN_STATE_OR_HANDSHAKING_V3:
return "handshaking (Tor, v3 handshake)";
case OR_CONN_STATE_OPEN: return "open";
}
break;

6
src/or/connection_or.c
View File

@ -387,7 +387,7 @@ connection_or_process_inbuf(or_connection_t *conn)
/* fall through. */
#endif
case OR_CONN_STATE_OPEN:
case OR_CONN_STATE_OR_HANDSHAKING:
case OR_CONN_STATE_OR_HANDSHAKING_V2:
return connection_or_process_cells_from_inbuf(conn);
default:
return 0; /* don't do anything */
@ -439,7 +439,7 @@ connection_or_finished_flushing(or_connection_t *conn)
switch (conn->_base.state) {
case OR_CONN_STATE_PROXY_HANDSHAKING:
case OR_CONN_STATE_OPEN:
case OR_CONN_STATE_OR_HANDSHAKING:
case OR_CONN_STATE_OR_HANDSHAKING_V2:
break;
default:
log_err(LD_BUG,"Called in unexpected state %d.", conn->_base.state);
@ -1476,7 +1476,7 @@ connection_tls_finish_handshake(or_connection_t *conn)
tor_tls_block_renegotiation(conn->tls);
return connection_or_set_state_open(conn);
} else {
conn->_base.state = OR_CONN_STATE_OR_HANDSHAKING;
conn->_base.state = OR_CONN_STATE_OR_HANDSHAKING_V2;
if (connection_init_or_handshake_state(conn, started_here) < 0)
return -1;
if (!started_here) {

32
src/or/or.h
View File

@ -283,22 +283,27 @@ typedef enum {
#define OR_CONN_STATE_CONNECTING 1
/** State for a connection to an OR: waiting for proxy handshake to complete */
#define OR_CONN_STATE_PROXY_HANDSHAKING 2
/** State for a connection to an OR or client: SSL is handshaking, not done
/** State for an OR connection client: SSL is handshaking, not done
* yet. */
#define OR_CONN_STATE_TLS_HANDSHAKING 3
/** State for a connection to an OR: We're doing a second SSL handshake for
* renegotiation purposes. */
* renegotiation purposes. (V2 handshake only.) */
#define OR_CONN_STATE_TLS_CLIENT_RENEGOTIATING 4
/** State for a connection at an OR: We're waiting for the client to
* renegotiate. */
* renegotiate (to indicate a v2 handshake) or send a versions cell (to
* indicate a v3 handshake) */
#define OR_CONN_STATE_TLS_SERVER_RENEGOTIATING 5
/** State for a connection to an OR: We're done with our SSL handshake, but we
* haven't yet negotiated link protocol versions and sent a netinfo cell.
*/
#define OR_CONN_STATE_OR_HANDSHAKING 6
/** State for a connection to an OR: Ready to send/receive cells. */
#define OR_CONN_STATE_OPEN 7
#define _OR_CONN_STATE_MAX 7
/** State for an OR connection: We're done with our SSL handshake, we've done
* renegotiation, but we haven't yet negotiated link protocol versions and
* sent a netinfo cell. */
#define OR_CONN_STATE_OR_HANDSHAKING_V2 6
/** State for an OR connection: We're done with our SSL handshake, but we
* haven't yet negotiated link protocol versions, done a V3 handshake, and
* sent a netinfo cell. */
#define OR_CONN_STATE_OR_HANDSHAKING_V3 7
/** State for an OR connection:: Ready to send/receive cells. */
#define OR_CONN_STATE_OPEN 8
#define _OR_CONN_STATE_MAX 8
#define _EXIT_CONN_STATE_MIN 1
/** State for an exit connection: waiting for response from DNS farm. */
@ -820,9 +825,10 @@ typedef enum {
#define CELL_NETINFO 8
#define CELL_RELAY_EARLY 9
/** True iff the cell command <b>x</b> is one that implies a variable-length
* cell. */
#define CELL_COMMAND_IS_VAR_LENGTH(x) ((x) == CELL_VERSIONS)
#define CELL_VPADDING 128
#define CELL_CERT 129
#define CELL_AUTH_CHALLENGE 130
#define CELL_AUTHENTICATE 131
/** How long to test reachability before complaining to the user. */
#define TIMEOUT_UNTIL_UNREACHABILITY_COMPLAINT (20*60)