From 452c6a53785c1ef8a85d5364e1c79c438a9c8670 Mon Sep 17 00:00:00 2001
From: goldsimon <goldsimon@gmx.de>
Date: Fri, 12 Jan 2018 22:25:34 +0100
Subject: [PATCH] netif: add netif_remove_ext_callback() (counterpart to
 netif_add_ext_callback())

---
 src/core/netif.c         | 38 ++++++++++++++++++++++++++++++++++++--
 src/include/lwip/netif.h |  2 ++
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/src/core/netif.c b/src/core/netif.c
index db00222a..9bb15c66 100644
--- a/src/core/netif.c
+++ b/src/core/netif.c
@@ -1637,7 +1637,8 @@ netif_find(const char *name)
  * @param callback pointer to listener structure
  * @param fn callback function
  */
-void netif_add_ext_callback(netif_ext_callback_t *callback, netif_ext_callback_fn fn)
+void
+netif_add_ext_callback(netif_ext_callback_t *callback, netif_ext_callback_fn fn)
 {
   LWIP_ASSERT_CORE_LOCKED();
   LWIP_ASSERT("callback must be != NULL", callback != NULL);
@@ -1648,13 +1649,46 @@ void netif_add_ext_callback(netif_ext_callback_t *callback, netif_ext_callback_f
   ext_callback          = callback;
 }
 
+/**
+ * @ingroup netif
+ * Remove extended netif events listener
+ * @param callback pointer to listener structure
+ */
+void
+netif_remove_ext_callback(netif_ext_callback_t* callback)
+{
+  netif_ext_callback_t *last, *iter;
+
+  LWIP_ASSERT_CORE_LOCKED();
+  LWIP_ASSERT("callback must be != NULL", callback != NULL);
+
+  if (ext_callback == NULL) {
+    return;
+  }
+
+  if (callback == ext_callback) {
+    ext_callback = ext_callback->next;
+  } else {
+    last = ext_callback;
+    for (iter = ext_callback->next; iter != NULL; last = iter, iter = iter->next) {
+      if (iter == callback) {
+        LWIP_ASSERT("last != NULL", last != NULL);
+        last->next = callback->next;
+        callback->next = NULL;
+        return;
+      }
+    }
+  }
+}
+
 /**
  * Invoke extended netif status event
  * @param netif netif that is affected by change
  * @param reason change reason
  * @param args depends on reason, see reason description
  */
-void netif_invoke_ext_callback(struct netif *netif, netif_nsc_reason_t reason, const netif_ext_callback_args_t *args)
+void
+netif_invoke_ext_callback(struct netif *netif, netif_nsc_reason_t reason, const netif_ext_callback_args_t *args)
 {
   netif_ext_callback_t *callback = ext_callback;
 
diff --git a/src/include/lwip/netif.h b/src/include/lwip/netif.h
index dfd87556..bb7362fb 100644
--- a/src/include/lwip/netif.h
+++ b/src/include/lwip/netif.h
@@ -633,10 +633,12 @@ typedef struct netif_ext_callback
 
 #define NETIF_DECLARE_EXT_CALLBACK(name) static netif_ext_callback_t name;
 void netif_add_ext_callback(netif_ext_callback_t* callback, netif_ext_callback_fn fn);
+void netif_remove_ext_callback(netif_ext_callback_t* callback);
 void netif_invoke_ext_callback(struct netif* netif, netif_nsc_reason_t reason, const netif_ext_callback_args_t* args);
 #else
 #define NETIF_DECLARE_EXT_CALLBACK(name)
 #define netif_add_ext_callback(callback, fn)
+#define netif_remove_ext_callback(callback)
 #define netif_invoke_ext_callback(netif, reason, args)
 #endif