From a63a33861fd636c9e6f59d82d076fedfa98a12f6 Mon Sep 17 00:00:00 2001
From: Max Lv <max.c.lv@gmail.com>
Date: Thu, 8 Dec 2016 14:48:40 +0800
Subject: [PATCH] Add container_of

---
 src/local.c    | 4 ++--
 src/redir.c    | 5 +++--
 src/server.c   | 4 ++--
 src/tunnel.c   | 5 +++--
 src/udprelay.c | 4 ++--
 src/utils.h    | 5 +++++
 6 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/src/local.c b/src/local.c
index 7a048856..0a62612e 100644
--- a/src/local.c
+++ b/src/local.c
@@ -744,8 +744,8 @@ stat_update_cb()
 static void
 remote_timeout_cb(EV_P_ ev_timer *watcher, int revents)
 {
-    remote_ctx_t *remote_ctx = (remote_ctx_t *)(((char *)watcher)
-                                                - sizeof(ev_io));
+    remote_ctx_t *remote_ctx
+        = (remote_ctx_t *)container_of(watcher, remote_ctx_t, watcher);
     remote_t *remote = remote_ctx->remote;
     server_t *server = remote->server;
 
diff --git a/src/redir.c b/src/redir.c
index f321428f..a9cbc0f8 100644
--- a/src/redir.c
+++ b/src/redir.c
@@ -328,8 +328,9 @@ server_send_cb(EV_P_ ev_io *w, int revents)
 static void
 remote_timeout_cb(EV_P_ ev_timer *watcher, int revents)
 {
-    remote_ctx_t *remote_ctx = (remote_ctx_t *)(((char *)watcher)
-                                                - sizeof(ev_io));
+    remote_ctx_t *remote_ctx
+        = (remote_ctx_t *)container_of(watcher, remote_ctx_t, watcher);
+
     remote_t *remote = remote_ctx->remote;
     server_t *server = remote->server;
 
diff --git a/src/server.c b/src/server.c
index 53bbf71c..593c51c9 100644
--- a/src/server.c
+++ b/src/server.c
@@ -1049,8 +1049,8 @@ block_list_clear_cb(EV_P_ ev_timer *watcher, int revents)
 static void
 server_timeout_cb(EV_P_ ev_timer *watcher, int revents)
 {
-    server_ctx_t *server_ctx = (server_ctx_t *)(((char *)watcher)
-                                                - sizeof(ev_io));
+    server_ctx_t *server_ctx
+        = (server_ctx_t *)container_of(watcher, server_ctx_t, watcher);
     server_t *server = server_ctx->server;
     remote_t *remote = server->remote;
 
diff --git a/src/tunnel.c b/src/tunnel.c
index dbd44298..a403f576 100644
--- a/src/tunnel.c
+++ b/src/tunnel.c
@@ -284,8 +284,9 @@ server_send_cb(EV_P_ ev_io *w, int revents)
 static void
 remote_timeout_cb(EV_P_ ev_timer *watcher, int revents)
 {
-    remote_ctx_t *remote_ctx = (remote_ctx_t *)(((char *)watcher)
-                                                - sizeof(ev_io));
+    remote_ctx_t *remote_ctx
+        = (remote_ctx_t *)container_of(watcher, remote_ctx_t, watcher);
+
     remote_t *remote = remote_ctx->remote;
     server_t *server = remote->server;
 
diff --git a/src/udprelay.c b/src/udprelay.c
index f3dd6f9a..3be0414b 100644
--- a/src/udprelay.c
+++ b/src/udprelay.c
@@ -549,8 +549,8 @@ close_and_free_remote(EV_P_ remote_ctx_t *ctx)
 static void
 remote_timeout_cb(EV_P_ ev_timer *watcher, int revents)
 {
-    remote_ctx_t *remote_ctx = (remote_ctx_t *)(((char *)watcher)
-                                                - sizeof(ev_io));
+    remote_ctx_t *remote_ctx
+        = (remote_ctx_t *)container_of(watcher, remote_ctx_t, watcher);
 
     if (verbose) {
         LOGI("[udp] connection timeout");
diff --git a/src/utils.h b/src/utils.h
index 8574a19c..f94ab1f4 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -228,4 +228,9 @@ void *ss_realloc(void *ptr, size_t new_size);
         ptr = NULL;      \
     } while (0)
 
+#ifndef container_of
+#define container_of(ptr, type, member) \
+                          ((type *) ((char *)(ptr) - offsetof(type, member)))
+#endif
+
 #endif // _UTILS_H