gnrc_sixlowpan_frag: initial import of minimal forwarding

See https://tools.ietf.org/html/draft-ietf-6lo-minimal-fragment-04

sys/Makefile.dep

@@ -292,6 +292,13 @@ ifneq (,$(filter gnrc_sixlowpan_frag_fb,$(USEMODULE)))
   USEMODULE += core_msg
 endif
 
+ifneq (,$(filter gnrc_sixlowpan_frag_minfwd,$(USEMODULE)))
+  USEMODULE += gnrc_netif_pktq
+  USEMODULE += gnrc_sixlowpan_frag
+  USEMODULE += gnrc_sixlowpan_frag_hint
+  USEMODULE += gnrc_sixlowpan_frag_vrb
+endif
+
 ifneq (,$(filter gnrc_sixlowpan_frag_rb,$(USEMODULE)))
   USEMODULE += xtimer
 endif

sys/include/net/gnrc/sixlowpan/frag/minfwd.h

@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+/**
+ * @defgroup    net_gnrc_sixlowpan_frag_minfwd  Minimal fragment forwarding
+ * @ingroup     net_gnrc_sixlowpan_frag
+ * @brief       Provides minimal fragment forwarding using the VRB
+ * @see         [RFC 8930](https://tools.ietf.org/html/rfc8930)
+ * @see         @ref net_gnrc_sixlowpan_frag_vrb
+ * @experimental
+ * @{
+ *
+ * @file
+ * @brief   Minimal fragment forwarding definitions
+ *
+ * @author  Martine Lenders <m.lenders@fu-berlin.de>
+ */
+#ifndef NET_GNRC_SIXLOWPAN_FRAG_MINFWD_H
+#define NET_GNRC_SIXLOWPAN_FRAG_MINFWD_H
+
+#include <stddef.h>
+
+#include "net/gnrc/pkt.h"
+#include "net/gnrc/netif.h"
+#include "net/gnrc/sixlowpan/frag.h"
+#include "net/gnrc/sixlowpan/frag/vrb.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief   Forwards a fragment according to a VRB entry
+ *
+ * @param[in] pkt       The fragment to forward (without fragmentation header).
+ *                      Is consumed by this function.
+ * @param[in] frag      The originally received fragmentation header.
+ * @param[in] vrbe      Virtual reassembly buffer containing the forwarding
+ *                      information. Removed when datagram was completely
+ *                      forwarded.
+ * @param[in] page      Current 6Lo dispatch parsing page.
+ *
+ * @pre `vrbe != NULL`
+ * @pre `pkt != NULL`
+ * @pre `frag != NULL`
+ *
+ * @return  0 on success.
+ * @return  -ENOMEM, when packet buffer is too full to prepare packet for
+ *          forwarding.
+ */
+int gnrc_sixlowpan_frag_minfwd_forward(gnrc_pktsnip_t *pkt,
+                                       const sixlowpan_frag_n_t *frag,
+                                       gnrc_sixlowpan_frag_vrb_t *vrbe,
+                                       unsigned page);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* NET_GNRC_SIXLOWPAN_FRAG_MINFWD_H */
+/** @} */

sys/net/gnrc/Makefile

@@ -100,6 +100,9 @@ endif
 ifneq (,$(filter gnrc_sixlowpan_frag_fb,$(USEMODULE)))
   DIRS += network_layer/sixlowpan/frag/fb
 endif
+ifneq (,$(filter gnrc_sixlowpan_frag_minfwd,$(USEMODULE)))
+  DIRS += network_layer/sixlowpan/frag/minfwd
+endif
 ifneq (,$(filter gnrc_sixlowpan_frag_rb,$(USEMODULE)))
   DIRS += network_layer/sixlowpan/frag/rb
 endif

sys/net/gnrc/network_layer/sixlowpan/frag/minfwd/Makefile

@@ -0,0 +1,3 @@
+MODULE := gnrc_sixlowpan_frag_minfwd
+
+include $(RIOTBASE)/Makefile.base

sys/net/gnrc/network_layer/sixlowpan/frag/minfwd/gnrc_sixlowpan_frag_minfwd.c

@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2019 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 <m.lenders@fu-berlin.de>
+ */
+
+#include <errno.h>
+#include <stdbool.h>
+
+#include "net/gnrc/netif/hdr.h"
+#include "net/gnrc/pktbuf.h"
+#include "net/gnrc/sixlowpan/internal.h"
+#include "utlist.h"
+
+#include "net/gnrc/sixlowpan/frag/minfwd.h"
+
+#define ENABLE_DEBUG    0
+#include "debug.h"
+
+static gnrc_pktsnip_t *_netif_hdr_from_vrbe(const gnrc_sixlowpan_frag_vrb_t *vrbe)
+{
+    gnrc_pktsnip_t *res = gnrc_netif_hdr_build(NULL, 0, vrbe->super.dst,
+                                               vrbe->super.dst_len);
+    if (res == NULL) {
+        DEBUG("6lo minfwd: can't allocate netif header for forwarding.\n");
+        return NULL;
+    }
+    gnrc_netif_hdr_set_netif(res->data, vrbe->out_netif);
+    return res;
+}
+
+static inline bool _is_last_frag(const gnrc_sixlowpan_frag_vrb_t *vrbe)
+{
+    return (vrbe->super.current_size >= vrbe->super.datagram_size);
+}
+
+int gnrc_sixlowpan_frag_minfwd_forward(gnrc_pktsnip_t *pkt,
+                                       const sixlowpan_frag_n_t *frag,
+                                       gnrc_sixlowpan_frag_vrb_t *vrbe,
+                                       unsigned page)
+{
+    sixlowpan_frag_t *new;
+    gnrc_pktsnip_t *tmp;
+    const size_t fragsnip_size = sizeof(sixlowpan_frag_t) +
+                                 ((sixlowpan_frag_1_is((sixlowpan_frag_t *)frag))
+                                 ? 0U : sizeof(frag->offset));
+
+    assert(vrbe != NULL);
+    assert(pkt != NULL);
+    assert(frag != NULL);
+    if ((tmp = gnrc_pktbuf_add(pkt, frag, fragsnip_size,
+                               GNRC_NETTYPE_SIXLOWPAN)) == NULL) {
+        DEBUG("6lo minfwd: unable to allocate new fragmentation header.\n");
+        gnrc_pktbuf_release(pkt);
+        return -ENOMEM;
+    }
+    pkt = tmp;
+    new = pkt->data;
+    new->tag = byteorder_htons(vrbe->out_tag);
+    tmp = _netif_hdr_from_vrbe(vrbe);
+    if (tmp == NULL) {
+        gnrc_pktbuf_release(pkt);
+        return -ENOMEM;
+    }
+    if (_is_last_frag(vrbe)) {
+        DEBUG("6lo minfwd: current_size (%u) >= datagram_size (%u)\n",
+              vrbe->super.current_size, vrbe->super.datagram_size);
+        gnrc_sixlowpan_frag_vrb_rm(vrbe);
+    }
+    else {
+        gnrc_netif_hdr_t *netif_hdr = tmp->data;
+
+        netif_hdr->flags |= GNRC_NETIF_HDR_FLAGS_MORE_DATA;
+    }
+    pkt = gnrc_pkt_prepend(pkt, tmp);
+    gnrc_sixlowpan_dispatch_send(pkt, NULL, page);
+    return 0;
+}
+
+/** @} */