gnrc_pkt: provide type search function

Makefile.dep

@@ -379,6 +379,7 @@ ifneq (,$(filter gnrc_pktbuf, $(USEMODULE)))
   ifeq (,$(filter gnrc_pktbuf_%, $(USEMODULE)))
     USEMODULE += gnrc_pktbuf_static
   endif
+  USEMODULE += gnrc_pkt
 endif
 
 ifneq (,$(filter gnrc_pktbuf_%, $(USEMODULE)))

sys/include/net/gnrc/pkt.h

@@ -155,6 +155,18 @@ static inline size_t gnrc_pkt_count(const gnrc_pktsnip_t *pkt)
     return count;
 }
 
+/**
+ * @brief   Searches the packet for a packet snip of a specific type
+ *
+ * @param[in] pkt   list of packet snips
+ * @param[in] type  the type to search for
+ *
+ * @return  the packet snip in @p pkt with @ref gnrc_nettype_t @p type
+ * @return  NULL, if none of the snips in @p pkt is of @p type
+ */
+gnrc_pktsnip_t *gnrc_pktsnip_search_type(gnrc_pktsnip_t *pkt,
+                                         gnrc_nettype_t type);
+
 #ifdef __cplusplus
 }
 #endif

sys/net/gnrc/Makefile

@@ -73,6 +73,9 @@ endif
 ifneq (,$(filter gnrc_nomac,$(USEMODULE)))
     DIRS += link_layer/nomac
 endif
+ifneq (,$(filter gnrc_pkt,$(USEMODULE)))
+    DIRS += pkt
+endif
 ifneq (,$(filter gnrc_pktbuf_static,$(USEMODULE)))
     DIRS += pktbuf_static
 endif

sys/net/gnrc/pkt/Makefile

+MODULE := gnrc_pkt
+
+include $(RIOTBASE)/Makefile.base

sys/net/gnrc/pkt/gnrc_pkt.c

+/*
+ * Copyright (C) 2016 Freie Universität Berlin
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @{
+ *
+ * @file
+ * @author  Martine Lenders <mlenders@inf.fu-berlin.de>
+ */
+
+#include <assert.h>
+
+#include "net/gnrc/pkt.h"
+
+gnrc_pktsnip_t *gnrc_pktsnip_search_type(gnrc_pktsnip_t *ptr,
+                                         gnrc_nettype_t type)
+{
+    while (ptr != NULL) {
+        if (ptr->type == type) {
+            return ptr;
+        }
+        ptr = ptr->next;
+    }
+    return NULL;
+}
+
+/** @} */