修正当进程句柄限制不足时，存在的随机关闭FD的问题并调整SSL关闭时的fd处理位置。

* 原实现在接收fd时，没有考虑可能只接收1个fd的情况。导致程序在接收1个fd时按2个fd处理，越界访问随机关闭fd。
* 现修正，接收2个一下fd时，关闭接收的fd。
* 同时调整SSL连接的FD关闭位置，改为在conn_private销毁时统一关闭，不在ssl部分关闭。

platform/include/internal/ssl_stream_core.h

@@ -42,7 +42,7 @@ void ssl_async_downstream_create(struct future * f, struct ssl_mgr * mgr, struct
 	evutil_socket_t fd_downstream, struct tfe_stream* tcp_stream);
 
 
-void ssl_stream_free_and_close_fd(struct ssl_stream * s_stream, struct event_base * evbase, struct bufferevent * bev);
+void ssl_stream_free(struct ssl_stream * s_stream, struct event_base * evbase, struct bufferevent * bev);
 const char* ssl_stream_dump_info(struct ssl_stream *stream, char* buffer, size_t sz);
 //Follow functions are allowed to call during runtime.
 int ssl_manager_add_trust_ca(struct ssl_mgr* mgr, const char* pem_file);

platform/src/acceptor_kni_v2.cpp

@@ -47,6 +47,8 @@ void acceptor_kni_v2_event(evutil_socket_t fd, short what, void * user)
     struct tfe_cmsg * cmsg = NULL;
 
 	int * __fds = NULL;
+	unsigned int __nr_fds = 0;
+
 	assert(__ctx != NULL && __ctx->thread == pthread_self());
 	assert(what & EV_READ);
 
@@ -91,11 +93,19 @@ void acceptor_kni_v2_event(evutil_socket_t fd, short what, void * user)
 		TFE_LOG_ERROR(__ctx->logger, "failed at fetch CMSG_FIRSTHDR() from incoming fds.");
 		goto __drop_recieved_fds;
 	}
-	
-	__fds = (int *) (CMSG_DATA(__cmsghdr));
-	if (unlikely(__fds == NULL))
+
+	switch(__cmsghdr->cmsg_len)
 	{
-		TFE_LOG_ERROR(__ctx->logger, "failed at fetch CMSG_DATA() from incoming fds.");
+		case CMSG_LEN(0 * sizeof(int)): { __nr_fds = 0; break;}
+		case CMSG_LEN(1 * sizeof(int)): { __nr_fds = 1; break;}
+		case CMSG_LEN(2 * sizeof(int)): { __nr_fds = 2; break; }
+		default: assert(0);
+	}
+
+	__fds = (int *) (CMSG_DATA(__cmsghdr));
+	if (unlikely(__fds == NULL || __nr_fds < 2))
+	{
+		TFE_LOG_ERROR(__ctx->logger, "No available file descriptors, drop the incoming fds.");
 		goto __drop_recieved_fds;
 	}
 
@@ -120,9 +130,13 @@ __die:
     return;
 
 __drop_recieved_fds:
-	TFE_PROXY_STAT_INCREASE(STAT_FD_CLOSE_BY_KNI_ACCEPT_FAIL, 2);
-	if (__fds != NULL) evutil_closesocket(__fds[0]);
-	if (__fds != NULL) evutil_closesocket(__fds[1]);
+	TFE_PROXY_STAT_INCREASE(STAT_FD_CLOSE_BY_KNI_ACCEPT_FAIL, __nr_fds);
+	for (unsigned int i = 0;  i < __nr_fds; i++)
+	{
+		evutil_closesocket(__fds[i]);
+	}
+
+	assert(__nr_fds <= 2);
 }
 
 void * acceptor_kni_v2_event_thread_entry(void * args)

platform/src/ssl_stream.cpp

@@ -2121,7 +2121,7 @@ complete:
  * Guarantees that SSL and the corresponding SSL_CTX are freed and the
  * socket is closed, eventually, or in the case of fatal errors, immediately.
  */
-void ssl_stream_free_and_close_fd(struct ssl_stream * s_stream, struct event_base * evbase, struct bufferevent * bev)
+void ssl_stream_free(struct ssl_stream * s_stream, struct event_base * evbase, struct bufferevent * bev)
 {
 	UNUSED struct ssl_shutdown_ctx * sslshutctx = NULL;
 	evutil_socket_t fd=-1;
@@ -2165,8 +2165,8 @@ void ssl_stream_free_and_close_fd(struct ssl_stream * s_stream, struct event_bas
 		bufferevent_setcb(ubev, NULL, NULL, NULL, NULL);
 		bufferevent_free(ubev);
 	}
+
 	ssl_stream_free(s_stream);
-	evutil_closesocket(fd);
 }
 
 int ssl_manager_add_trust_ca(struct ssl_mgr* mgr, const char* pem_file)

platform/src/tcp_stream.cpp

@@ -401,7 +401,11 @@ evutil_socket_t __conn_private_release_fd(struct tfe_conn_private * conn)
 
 static void __conn_private_destory(struct tfe_conn_private * conn)
 {
-	bufferevent_disable(conn->bev, EV_READ | EV_WRITE);
+	if (conn->bev)
+	{
+		bufferevent_disable(conn->bev, EV_READ | EV_WRITE);
+		bufferevent_free(conn->bev);
+	}
 
 	if(conn->ratelimit_bucket)
 	{
@@ -409,10 +413,9 @@ static void __conn_private_destory(struct tfe_conn_private * conn)
 		conn->ratelimit_bucket = NULL;
 	}
 
-	bufferevent_free(conn->bev);
 	if (conn->fd > 0)
 	{
-		evutil_closesocket(conn->fd);
+		assert(evutil_closesocket(conn->fd) >= 0);
 	}
 
 	free(conn);
@@ -423,8 +426,7 @@ static void __conn_private_destory_with_ssl(struct event_base * ev_base,
 	struct tfe_conn_private * conn, struct ssl_stream * ssl_stream)
 {
 	if (ssl_stream == NULL) return __conn_private_destory(conn);
-	ssl_stream_free_and_close_fd(ssl_stream, ev_base, conn->bev);
-	conn->fd = -1;
+	ssl_stream_free(ssl_stream, ev_base, conn->bev);
 	return __conn_private_destory(conn);
 }
 
@@ -1125,21 +1127,23 @@ void tfe_stream_destory(struct tfe_stream_private * stream)
 
 	if (__is_ssl(stream) && stream->ssl_upstream)
 	{
-		ssl_stream_free_and_close_fd(stream->ssl_upstream, ev_base, stream->conn_upstream->bev);
+		ssl_stream_free(stream->ssl_upstream, ev_base, stream->conn_upstream->bev);
 	}
 
 	if (__is_ssl(stream) && stream->ssl_downstream)
 	{
-		ssl_stream_free_and_close_fd(stream->ssl_downstream, ev_base, stream->conn_downstream->bev);
+		ssl_stream_free(stream->ssl_downstream, ev_base, stream->conn_downstream->bev);
 	}
 
 	if (stream->conn_upstream)
 	{
+		assert(stream->defer_fd_upstream <= 0);
 		__conn_private_destory(stream->conn_upstream);
 	}
 
 	if (stream->conn_downstream)
 	{
+		assert(stream->defer_fd_downstream <= 0);
 		__conn_private_destory(stream->conn_downstream);
 	}