netreg: add multiplexer for checksum calculation

sys/include/net/ng_netreg.h

@@ -126,6 +126,30 @@ int ng_netreg_num(ng_nettype_t type, uint32_t demux_ctx);
  */
 ng_netreg_entry_t *ng_netreg_getnext(ng_netreg_entry_t *entry);
 
+/**
+ * @brief   Calculates the checksum for a packet of type @p checksum_hdr_type.
+ *
+ * @param[in] pseudo_hdr_type   The type of the pseudo header if required.
+ *                              May be NG_NETTYPE_UNDEF if no pseudo header is
+ *                              required for the checksum calculation.
+ * @param[in] csum_hdr_type     The type of the packet the checksum should be
+ *                              calculated for
+ * @param[in,out] pkt           The packet the checksum should be calculated
+ *                              for.
+ *
+ * @return  0, on success.
+ * @return  -EBADMSG, @p pkt did not contain a header of type @p pseudo_hdr_type
+ *          (if not NG_NETTYPE_UNDEF) or @p csum_hdr_type
+ * @return  -EFAULT, @p pkt was NULL.
+ * @return  -EINVAL, if @p pseudo_hdr_type is NG_NETTYPE_UNDEF but a pseudo
+ *          header was required
+ * @return  -ENOENT, if @ref net_netreg does not know how to calculate checksum
+ *          for @p csum_hdr_type
+ */
+int ng_netreg_calculate_csum(ng_nettype_t pseudo_hdr_type,
+                             ng_nettype_t csum_hdr_type,
+                             ng_pktsnip_t *pkt);
+
 #ifdef __cplusplus
 }
 #endif

sys/net/crosslayer/ng_netreg/ng_netreg.c

@@ -19,6 +19,7 @@
 #include "utlist.h"
 #include "net/ng_netreg.h"
 #include "net/ng_nettype.h"
+#include "net/ng_ipv6.h"
 
 #define _INVALID_TYPE(type) (((type) <= NG_NETTYPE_UNDEF) || ((type) >= NG_NETTYPE_NUMOF))
 
@@ -101,4 +102,30 @@ ng_netreg_entry_t *ng_netreg_getnext(ng_netreg_entry_t *entry)
     return entry;
 }
 
+int ng_netreg_calculate_csum(ng_nettype_t pseudo_hdr_type,
+                             ng_nettype_t csum_hdr_type,
+                             ng_pktsnip_t *pkt)
+{
+    switch (csum_hdr_type) {
+#ifdef MODULE_NG_ICMPV6
+
+        case NG_NETTYPE_ICMPV6:
+            return ng_icmpv6_calculate_csum(pseudo_hdr_type, pkt);
+#endif
+#ifdef MODULE_NG_TCP
+
+        case NG_NETTYPE_TCP:
+            return ng_tcp_calculate_csum(pseudo_hdr_type, pkt);
+#endif
+#ifdef MODULE_NG_UDP
+
+        case NG_NETTYPE_UDP:
+            return ng_udp_calculate_csum(pseudo_hdr_type, pkt);
+#endif
+
+        default:
+            return -ENOENT;
+    }
+}
+
 /** @} */