gnrc: cleanup and corrections in gnrc_pkt

sys/include/net/gnrc/pkt.h

@@ -128,7 +128,7 @@ static inline size_t gnrc_pkt_len(gnrc_pktsnip_t *pkt)
 {
     size_t len = 0;
 
-    while (pkt) {
+    while (pkt != NULL) {
         len += pkt->size;
         pkt = pkt->next;
     }
@@ -148,7 +148,7 @@ static inline size_t gnrc_pkt_len_upto(gnrc_pktsnip_t *pkt, gnrc_nettype_t type)
 {
     size_t len = 0;
 
-    while (pkt) {
+    while (pkt != NULL) {
         len += pkt->size;
 
         if (pkt->type == type) {
@@ -172,7 +172,7 @@ static inline size_t gnrc_pkt_count(const gnrc_pktsnip_t *pkt)
 {
     size_t count = 0;
 
-    while (pkt) {
+    while (pkt != NULL) {
         ++count;
         pkt = pkt->next;
     }

sys/net/gnrc/pkt/gnrc_pkt.c

@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2016 Freie Universität Berlin
+ *               2017 HAW Hamburg
  *
  * 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
@@ -11,22 +12,18 @@
  *
  * @file
  * @author  Martine Lenders <mlenders@inf.fu-berlin.de>
+ * @author  Sebastian Meiling <s@mlng.net>
  */
 
-#include <assert.h>
-
 #include "net/gnrc/pkt.h"
 
-gnrc_pktsnip_t *gnrc_pktsnip_search_type(gnrc_pktsnip_t *ptr,
+gnrc_pktsnip_t *gnrc_pktsnip_search_type(gnrc_pktsnip_t *pkt,
                                          gnrc_nettype_t type)
 {
-    while (ptr != NULL) {
-        if (ptr->type == type) {
-            return ptr;
-        }
-        ptr = ptr->next;
+    while ((pkt != NULL) && (pkt->type != type)) {
+        pkt = pkt->next;
     }
-    return NULL;
+    return pkt;
 }
 
 /** @} */