new file mode 100644
--- /dev/null
+++ b/src/stream/ngx_stream_upstream.h
@@ -0,0 +1,103 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ * Copyright (C) Nginx, Inc.
+ */
+
+
+#ifndef _NGX_STREAM_UPSTREAM_H_INCLUDED_
+#define _NGX_STREAM_UPSTREAM_H_INCLUDED_
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_stream.h>
+#include <ngx_event_connect.h>
+
+
+#define NGX_STREAM_UPSTREAM_CREATE        0x0001
+#define NGX_STREAM_UPSTREAM_WEIGHT        0x0002
+#define NGX_STREAM_UPSTREAM_MAX_FAILS     0x0004
+#define NGX_STREAM_UPSTREAM_FAIL_TIMEOUT  0x0008
+#define NGX_STREAM_UPSTREAM_DOWN          0x0010
+#define NGX_STREAM_UPSTREAM_BACKUP        0x0020
+
+
+typedef struct {
+    ngx_array_t                        upstreams;
+                                           /* ngx_stream_upstream_srv_conf_t */
+} ngx_stream_upstream_main_conf_t;
+
+
+typedef struct ngx_stream_upstream_srv_conf_s  ngx_stream_upstream_srv_conf_t;
+
+
+typedef ngx_int_t (*ngx_stream_upstream_init_pt)(ngx_conf_t *cf,
+    ngx_stream_upstream_srv_conf_t *us);
+typedef ngx_int_t (*ngx_stream_upstream_init_peer_pt)(ngx_stream_session_t *s,
+    ngx_stream_upstream_srv_conf_t *us);
+
+
+typedef struct {
+    ngx_stream_upstream_init_pt        init_upstream;
+    ngx_stream_upstream_init_peer_pt   init;
+    void                              *data;
+} ngx_stream_upstream_peer_t;
+
+
+typedef struct {
+    ngx_str_t                          name;
+    ngx_addr_t                        *addrs;
+    ngx_uint_t                         naddrs;
+    ngx_uint_t                         weight;
+    ngx_uint_t                         max_fails;
+    time_t                             fail_timeout;
+
+    unsigned                           down:1;
+    unsigned                           backup:1;
+} ngx_stream_upstream_server_t;
+
+
+struct ngx_stream_upstream_srv_conf_s {
+    ngx_stream_upstream_peer_t         peer;
+    void                             **srv_conf;
+
+    ngx_array_t                       *servers;
+                                              /* ngx_stream_upstream_server_t */
+
+    ngx_uint_t                         flags;
+    ngx_str_t                          host;
+    u_char                            *file_name;
+    ngx_uint_t                         line;
+    in_port_t                          port;
+    ngx_uint_t                         no_port;  /* unsigned no_port:1 */
+
+#if (NGX_STREAM_UPSTREAM_ZONE)
+    ngx_shm_zone_t                    *shm_zone;
+#endif
+};
+
+
+typedef struct {
+    ngx_peer_connection_t              peer;
+    ngx_buf_t                          downstream_buf;
+    ngx_buf_t                          upstream_buf;
+    off_t                              received;
+#if (NGX_STREAM_SSL)
+    ngx_str_t                          ssl_name;
+#endif
+} ngx_stream_upstream_t;
+
+
+ngx_stream_upstream_srv_conf_t *ngx_stream_upstream_add(ngx_conf_t *cf,
+    ngx_url_t *u, ngx_uint_t flags);
+
+
+#define ngx_stream_conf_upstream_srv_conf(uscf, module)                       \
+    uscf->srv_conf[module.ctx_index]
+
+
+extern ngx_module_t  ngx_stream_upstream_module;
+
+
+#endif /* _NGX_STREAM_UPSTREAM_H_INCLUDED_ */