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[tor-commits] [tor/master] Make pending libevent actions cancelable
commit aba25a6939a5907d40dbcff7433a8c130ffd12ad
Author: Nick Mathewson <nickm@xxxxxxxxxxxxxx>
Date: Tue Nov 29 17:06:09 2011 -0500
Make pending libevent actions cancelable
This avoids a dangling pointer issue in the 3412 code, and should
fix bug 4599.
---
src/common/compat_libevent.c | 24 +++++++++++++++++-------
src/common/compat_libevent.h | 8 +++++---
src/common/tortls.c | 13 +++----------
src/or/connection_or.c | 25 +++++++++++++++++++++----
src/or/or.h | 2 ++
5 files changed, 48 insertions(+), 24 deletions(-)
diff --git a/src/common/compat_libevent.c b/src/common/compat_libevent.c
index 3a754be..67f4659 100644
--- a/src/common/compat_libevent.c
+++ b/src/common/compat_libevent.c
@@ -558,17 +558,17 @@ tor_check_libevent_header_compatibility(void)
#endif
}
-typedef struct runnable_t {
+struct tor_libevent_action_t {
struct event *ev;
void (*cb)(void *arg);
void *arg;
-} runnable_t;
+};
/** Callback for tor_run_in_libevent_loop */
static void
run_runnable_cb(evutil_socket_t s, short what, void *arg)
{
- runnable_t *r = arg;
+ tor_libevent_action_t *r = arg;
void (*cb)(void *) = r->cb;
void *cb_arg = r->arg;
(void)what;
@@ -584,22 +584,32 @@ run_runnable_cb(evutil_socket_t s, short what, void *arg)
* deep inside a no-reentrant code and there's some function you want to call
* without worrying about whether it might cause reeentrant invocation.
*/
-int
+tor_libevent_action_t *
tor_run_in_libevent_loop(void (*cb)(void *arg), void *arg)
{
- runnable_t *r = tor_malloc(sizeof(runnable_t));
+ tor_libevent_action_t *r = tor_malloc(sizeof(tor_libevent_action_t));
r->cb = cb;
r->arg = arg;
r->ev = tor_event_new(tor_libevent_get_base(), -1, EV_TIMEOUT,
run_runnable_cb, r);
if (!r->ev) {
tor_free(r);
- return -1;
+ return NULL;
}
/* Make the event active immediately. */
event_active(r->ev, EV_TIMEOUT, 1);
- return 0;
+ return r;
+}
+
+/**
+ * Cancel <b>action</b> without running it.
+ */
+void
+tor_cancel_libevent_action(tor_libevent_action_t *action)
+{
+ tor_event_free(action->ev);
+ tor_free(action);
}
/*
diff --git a/src/common/compat_libevent.h b/src/common/compat_libevent.h
index 3f916d1..4076cc0 100644
--- a/src/common/compat_libevent.h
+++ b/src/common/compat_libevent.h
@@ -44,10 +44,12 @@ void tor_event_free(struct event *ev);
#define tor_evdns_add_server_port evdns_add_server_port
#endif
-typedef struct periodic_timer_t periodic_timer_t;
-
-int tor_run_in_libevent_loop(void (*cb)(void *arg), void *arg);
+typedef struct tor_libevent_action_t tor_libevent_action_t;
+tor_libevent_action_t *tor_run_in_libevent_loop(void (*cb)(void *arg),
+ void *arg);
+void tor_cancel_libevent_action(tor_libevent_action_t *action);
+typedef struct periodic_timer_t periodic_timer_t;
periodic_timer_t *periodic_timer_new(struct event_base *base,
const struct timeval *tv,
void (*cb)(periodic_timer_t *timer, void *data),
diff --git a/src/common/tortls.c b/src/common/tortls.c
index b4d81de..a6947c8 100644
--- a/src/common/tortls.c
+++ b/src/common/tortls.c
@@ -1339,16 +1339,9 @@ tor_tls_got_client_hello(tor_tls_t *tls)
tls->excess_renegotiations_callback) {
/* We got more than one renegotiation requests. The Tor protocol
needs just one renegotiation; more than that probably means
- They are trying to DoS us and we have to stop them. We can't
- close their connection from in here since it's an OpenSSL
- callback, so we set a libevent timer that triggers in the next
- event loop and closes the connection. */
-
- if (tor_run_in_libevent_loop(tls->excess_renegotiations_callback,
- tls->callback_arg) < 0) {
- log_warn(LD_GENERAL, "Didn't manage to set a renegotiation "
- "limiting callback.");
- }
+ They are trying to DoS us and we have to stop them. */
+
+ tls->excess_renegotiations_callback(tls->callback_arg);
}
/* Now check the cipher list. */
diff --git a/src/or/connection_or.c b/src/or/connection_or.c
index e868b7b..246b08a 100644
--- a/src/or/connection_or.c
+++ b/src/or/connection_or.c
@@ -492,6 +492,9 @@ connection_or_about_to_close(or_connection_t *or_conn)
time_t now = time(NULL);
connection_t *conn = TO_CONN(or_conn);
+ if (or_conn->pending_action)
+ tor_cancel_libevent_action(or_conn->pending_action);
+
/* Remember why we're closing this connection. */
if (conn->state != OR_CONN_STATE_OPEN) {
/* Inform any pending (not attached) circs that they should
@@ -1153,20 +1156,34 @@ connection_or_tls_renegotiated_cb(tor_tls_t *tls, void *_conn)
}
}
-/** Invoked on the server side using a timer from inside
- * tor_tls_got_client_hello() when the server receives excess
- * renegotiation attempts; probably indicating a DoS. */
+/*DOCDOC*/
static void
-connection_or_close_connection_cb(void *_conn)
+close_connection_libevent_cb(void *_conn)
{
or_connection_t *or_conn = _conn;
connection_t *conn = TO_CONN(or_conn);
+ or_conn->pending_action = NULL;
+
connection_stop_reading(conn);
if (!conn->marked_for_close)
connection_mark_for_close(conn);
}
+/* DOCDOC */
+static void
+connection_or_close_connection_cb(void *_conn)
+{
+ /* We can't close their connection from in here since it's an OpenSSL
+ callback, so we set a libevent event that triggers in the next event
+ loop and closes the connection. */
+ or_connection_t *or_conn = _conn;
+ if (or_conn->_base.marked_for_close || or_conn->pending_action)
+ return;
+ or_conn->pending_action =
+ tor_run_in_libevent_loop(close_connection_libevent_cb, or_conn);
+}
+
/** Move forward with the tls handshake. If it finishes, hand
* <b>conn</b> to connection_tls_finish_handshake().
*
diff --git a/src/or/or.h b/src/or/or.h
index 546fe17..185d20d 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -1272,6 +1272,8 @@ typedef struct or_connection_t {
unsigned active_circuit_pqueue_last_recalibrated;
struct or_connection_t *next_with_same_id; /**< Next connection with same
* identity digest as this one. */
+
+ tor_libevent_action_t *pending_action;
} or_connection_t;
/** Subtype of connection_t for an "edge connection" -- that is, an entry (ap)
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