/** Process a 'versions' cell. The current link protocol version must be 0
* to indicate that no version has yet been negotiated. We compare the
* versions in the cell to the list of versions we support, pick the
* highest version we have in common, and continue the negotiation from
* there.
*/
static void
command_process_versions_cell(var_cell_t *cell, or_connection_t *conn)
{
int highest_supported_version = 0;
const char *cp, *end;
if (conn->link_proto != 0 ||
conn->_base.state != OR_CONN_STATE_OR_HANDSHAKING ||
(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 "
"already set to %d; dropping", (int) conn->link_proto);
return;
}
tor_assert(conn->handshake_state);
end = cell->payload + cell->payload_len;
for (cp = cell->payload; cp+1 < end; ++cp) {
uint16_t v = ntohs(get_uint16(cp));
if (is_or_protocol_version_known(v) && v > highest_supported_version)
highest_supported_version = v;
}
if (!highest_supported_version) {
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"Couldn't find a version in common between my version list and the "
"list in the VERSIONS cell; closing connection.");
connection_mark_for_close(TO_CONN(conn));
return;
} else if (highest_supported_version == 1) {
/* Negotiating version 1 makes no sense, since version 1 has no VERSIONS
* cells. */
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"Used version negotiation protocol to negotiate a v1 connection. "
"That's crazily non-compliant. Closing connection.");
connection_mark_for_close(TO_CONN(conn));
return;
}
conn->link_proto = highest_supported_version;
conn->handshake_state->received_versions = 1;
log_info(LD_OR, "Negotiated version %d with %s:%d; sending NETINFO.",
highest_supported_version, safe_str(conn->_base.address),
conn->_base.port);
tor_assert(conn->link_proto >= 2);
if (connection_or_send_netinfo(conn) < 0) {
connection_mark_for_close(TO_CONN(conn));
return;
}
}
/** Process a 'versions' cell. The current link protocol version must be 0
* to indicate that no version has yet been negotiated. We compare the
* versions in the cell to the list of versions we support, pick the
* highest version we have in common, and continue the negotiation from
* there.
*/
static void
command_process_versions_cell(var_cell_t *cell, or_connection_t *conn)
{
int highest_supported_version = 0;
const uint8_t *cp, *end;
const int started_here = connection_or_nonopen_was_started_here(conn);
if (conn->link_proto != 0 ||
(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 "
"already set to %d; dropping", (int) conn->link_proto);
return;
}
switch (conn->_base.state)
{
case OR_CONN_STATE_OR_HANDSHAKING_V2:
case OR_CONN_STATE_OR_HANDSHAKING_V3:
break;
case OR_CONN_STATE_TLS_HANDSHAKING:
case OR_CONN_STATE_TLS_SERVER_RENEGOTIATING:
default:
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"VERSIONS cell while in unexpected state");
return;
}
tor_assert(conn->handshake_state);
end = cell->payload + cell->payload_len;
for (cp = cell->payload; cp+1 < end; ++cp) {
uint16_t v = ntohs(get_uint16(cp));
if (is_or_protocol_version_known(v) && v > highest_supported_version)
highest_supported_version = v;
}
if (!highest_supported_version) {
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"Couldn't find a version in common between my version list and the "
"list in the VERSIONS cell; closing connection.");
connection_mark_for_close(TO_CONN(conn));
return;
} else if (highest_supported_version == 1) {
/* Negotiating version 1 makes no sense, since version 1 has no VERSIONS
* cells. */
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"Used version negotiation protocol to negotiate a v1 connection. "
"That's crazily non-compliant. Closing connection.");
connection_mark_for_close(TO_CONN(conn));
return;
} else if (highest_supported_version < 3 &&
conn->_base.state == OR_CONN_STATE_OR_HANDSHAKING_V3) {
log_fn(LOG_PROTOCOL_WARN, LD_OR,
"Negotiated link protocol 2 or lower after doing a v3 TLS "
"handshake. Closing connection.");
connection_mark_for_close(TO_CONN(conn));
return;
}
conn->link_proto = highest_supported_version;
conn->handshake_state->received_versions = 1;
if (conn->link_proto == 2) {
log_info(LD_OR, "Negotiated version %d with %s:%d; sending NETINFO.",
highest_supported_version,
safe_str_client(conn->_base.address),
conn->_base.port);
if (connection_or_send_netinfo(conn) < 0) {
connection_mark_for_close(TO_CONN(conn));
return;
}
} else {
const int send_versions = !started_here;
/* If we want to authenticate, send a CERTS cell */
const int send_certs = !started_here || public_server_mode(get_options());
/* If we're a relay that got a connection, ask for authentication. */
const int send_chall = !started_here && public_server_mode(get_options());
/* If our certs cell will authenticate us, or if we have no intention of
* authenticating, send a netinfo cell right now. */
const int send_netinfo =
!(started_here && public_server_mode(get_options()));
const int send_any =
send_versions || send_certs || send_chall || send_netinfo;
tor_assert(conn->link_proto >= 3);
log_info(LD_OR, "Negotiated version %d with %s:%d; %s%s%s%s%s",
highest_supported_version,
safe_str_client(conn->_base.address),
conn->_base.port,
send_any ? "Sending cells:" : "Waiting for CERTS cell",
send_versions ? " VERSIONS" : "",
send_certs ? " CERTS" : "",
send_chall ? " AUTH_CHALLENGE" : "",
send_netinfo ? " NETINFO" : "");
#ifdef DISABLE_V3_LINKPROTO_SERVERSIDE
if (1) {
connection_mark_for_close(TO_CONN(conn));
return;
}
#endif
if (send_versions) {
if (connection_or_send_versions(conn, 1) < 0) {
log_warn(LD_OR, "Couldn't send versions cell");
connection_mark_for_close(TO_CONN(conn));
return;
}
}
if (send_certs) {
if (connection_or_send_certs_cell(conn) < 0) {
log_warn(LD_OR, "Couldn't send certs cell");
connection_mark_for_close(TO_CONN(conn));
return;
}
}
if (send_chall) {
if (connection_or_send_auth_challenge_cell(conn) < 0) {
log_warn(LD_OR, "Couldn't send auth_challenge cell");
connection_mark_for_close(TO_CONN(conn));
return;
}
}
if (send_netinfo) {
if (connection_or_send_netinfo(conn) < 0) {
log_warn(LD_OR, "Couldn't send netinfo cell");
connection_mark_for_close(TO_CONN(conn));
return;
}
}
}
}
/** Process an AUTH_CHALLENGE cell from an OR connection.
*
* If we weren't supposed to get one (for example, because we're not the
* originator of the connection), or it's ill-formed, or we aren't doing a v3
* handshake, mark the connection. If the cell is well-formed but we don't
* want to authenticate, just drop it. If the cell is well-formed *and* we
* want to authenticate, send an AUTHENTICATE cell and then a NETINFO cell. */
static void
command_process_auth_challenge_cell(var_cell_t *cell, or_connection_t *conn)
{
int n_types, i, use_type = -1;
uint8_t *cp;
#define ERR(s) \
do { \
log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, \
"Received a bad AUTH_CHALLENGE cell from %s:%d: %s", \
safe_str(conn->_base.address), conn->_base.port, (s)); \
connection_mark_for_close(TO_CONN(conn)); \
return; \
} while (0)
if (conn->_base.state != OR_CONN_STATE_OR_HANDSHAKING_V3)
ERR("We're not currently doing a v3 handshake");
if (conn->link_proto < 3)
ERR("We're not using link protocol >= 3");
if (! conn->handshake_state->started_here)
ERR("We didn't originate this connection");
if (conn->handshake_state->received_auth_challenge)
ERR("We already received one");
if (! conn->handshake_state->received_certs_cell)
ERR("We haven't gotten a CERTS cell yet");
if (cell->payload_len < OR_AUTH_CHALLENGE_LEN + 2)
ERR("It was too short");
if (cell->circ_id)
ERR("It had a nonzero circuit ID");
n_types = ntohs(get_uint16(cell->payload + OR_AUTH_CHALLENGE_LEN));
if (cell->payload_len < OR_AUTH_CHALLENGE_LEN + 2 + 2*n_types)
ERR("It looks truncated");
/* Now see if there is an authentication type we can use */
cp=cell->payload+OR_AUTH_CHALLENGE_LEN+2;
for (i=0; i < n_types; ++i, cp += 2) {
uint16_t authtype = ntohs(get_uint16(cp));
if (authtype == AUTHTYPE_RSA_SHA256_TLSSECRET)
use_type = authtype;
}
conn->handshake_state->received_auth_challenge = 1;
if (! public_server_mode(get_options())) {
/* If we're not a public server then we don't want to authenticate on a
connection we originated, and we already sent a NETINFO cell when we
got the CERTS cell. We have nothing more to do. */
return;
}
if (use_type >= 0) {
log_info(LD_OR, "Got an AUTH_CHALLENGE cell from %s:%d: Sending "
"authentication",
safe_str(conn->_base.address), conn->_base.port);
if (connection_or_send_authenticate_cell(conn, use_type) < 0) {
log_warn(LD_OR, "Couldn't send authenticate cell");
connection_mark_for_close(TO_CONN(conn));
return;
}
} else {
log_info(LD_OR, "Got an AUTH_CHALLENGE cell from %s:%d, but we don't "
"know any of its authentication types. Not authenticating.",
safe_str(conn->_base.address), conn->_base.port);
}
if (connection_or_send_netinfo(conn) < 0) {
log_warn(LD_OR, "Couldn't send netinfo cell");
connection_mark_for_close(TO_CONN(conn));
return;
}
#undef ERR
}
