Commit aef30547 authored by Nick Mathewson's avatar Nick Mathewson 👁
Browse files

Add an option to limit the number of non-open client circuits.

This is mainly meant as a way to keep clients from accidentally
DOSing themselves by (e.g.) enabling IsolateDestAddr or
IsolateDestPort on a port that they use for HTTP.
parent 20c0581a
......@@ -288,6 +288,27 @@ circuit_get_best(const edge_connection_t *conn,
return best;
}
/** Return the number of not-yet-open general-purpose origin circuits. */
static int
count_pending_general_client_circuits(void)
{
const circuit_t *circ;
int count = 0;
for (circ = global_circuitlist; circ; circ = circ->next) {
if (circ->marked_for_close ||
circ->state == CIRCUIT_STATE_OPEN ||
circ->purpose != CIRCUIT_PURPOSE_C_GENERAL ||
!CIRCUIT_IS_ORIGIN(circ))
continue;
++count;
}
return count;
}
#if 0
/** Check whether, according to the policies in <b>options</b>, the
* circuit <b>circ</b> makes sense. */
......@@ -1347,6 +1368,20 @@ circuit_get_open_circ_or_launch(edge_connection_t *conn,
if (!circ) {
extend_info_t *extend_info=NULL;
uint8_t new_circ_purpose;
const int n_pending = count_pending_general_client_circuits();
if (n_pending >= options->MaxClientCircuitsPending) {
static ratelim_t delay_limit = RATELIM_INIT(10*60);
char *m;
if ((m = rate_limit_log(&delay_limit, approx_time()))) {
log_notice(LD_APP, "We'd like to launch a circuit to handle a "
"connection, but we already have %d general-purpose client "
"circuits pending. Waiting until some finish.",
n_pending);
tor_free(m);
}
return 0;
}
if (desired_circuit_purpose == CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT) {
/* need to pick an intro point */
......
......@@ -315,6 +315,7 @@ static config_var_t _option_vars[] = {
VAR("MapAddress", LINELIST, AddressMap, NULL),
V(MaxAdvertisedBandwidth, MEMUNIT, "1 GB"),
V(MaxCircuitDirtiness, INTERVAL, "10 minutes"),
V(MaxClientCircuitsPending, UINT, "32"),
V(MaxOnionsPending, UINT, "100"),
OBSOLETE("MonthlyAccountingStart"),
V(MyFamily, STRING, NULL),
......@@ -3215,6 +3216,15 @@ options_validate(or_options_t *old_options, or_options_t *options,
return -1;
}
if (options->MaxClientCircuitsPending <= 0 ||
options->MaxClientCircuitsPending > MAX_MAX_CLIENT_CIRCUITS_PENDING) {
tor_asprintf(msg,
"MaxClientCircuitsPending must be between 1 and %d, but "
"was set to %d", MAX_MAX_CLIENT_CIRCUITS_PENDING,
options->MaxClientCircuitsPending);
return -1;
}
if (validate_ports_csv(options->FirewallPorts, "FirewallPorts", msg) < 0)
return -1;
......
......@@ -3230,6 +3230,11 @@ typedef struct {
/** Should that file be group-readable? */
int ControlPortFileGroupReadable;
#define MAX_MAX_CLIENT_CIRCUITS_PENDING 1024
/** Maximum number of non-open general-purpose origin circuits to allow at
* once. */
int MaxClientCircuitsPending;
} or_options_t;
/** Persistent state for an onion router, as saved to disk. */
......
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