stream: Make sure no watcher callback is active while changing stream callbacks

When changing async callbacks on streams, we have to make sure the watcher
callback is not currently active and has temporarily disabled callbacks. This
could have been the case, as we didn't explicitly removed any pending
watcher registration if both callbacks are NULL.

By enforcing the watcher unregistration, we are sure the watcher callback is
not active and currently is not mangling the callback hooks. This should make
sure we avoid any races for the callback variables.

1 files changed, 3 insertions, 14 deletions

diff --git a/src/libstrongswan/networking/streams/stream.c b/src/libstrongswan/networking/streams/stream.c
index 8ecb89fc9..f6fec0b4a 100644
--- a/src/libstrongswan/networking/streams/stream.c
+++ b/src/libstrongswan/networking/streams/stream.c
@@ -159,17 +159,6 @@ METHOD(stream_t, write_all, bool,
 }
 
 /**
- * Remove a registered watcher
- */
-static void remove_watcher(private_stream_t *this)
-{
-	if (this->read_cb || this->write_cb)
-	{
-		lib->watcher->remove(lib->watcher, this->fd);
-	}
-}
-
-/**
  * Watcher callback
  */
 static bool watch(private_stream_t *this, int fd, watcher_event_t event)
@@ -228,7 +217,7 @@ static void add_watcher(private_stream_t *this)
 METHOD(stream_t, on_read, void,
 	private_stream_t *this, stream_cb_t cb, void *data)
 {
-	remove_watcher(this);
+	lib->watcher->remove(lib->watcher, this->fd);
 
 	this->read_cb = cb;
 	this->read_data = data;
@@ -239,7 +228,7 @@ METHOD(stream_t, on_read, void,
 METHOD(stream_t, on_write, void,
 	private_stream_t *this, stream_cb_t cb, void *data)
 {
-	remove_watcher(this);
+	lib->watcher->remove(lib->watcher, this->fd);
 
 	this->write_cb = cb;
 	this->write_data = data;
@@ -270,7 +259,7 @@ METHOD(stream_t, get_file, FILE*,
 METHOD(stream_t, destroy, void,
 	private_stream_t *this)
 {
-	remove_watcher(this);
+	lib->watcher->remove(lib->watcher, this->fd);
 	close(this->fd);
 	free(this);
 }