gnrc_sixlowpan_frag: initial import of minimal forwarding

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/fb.h

@@ -25,6 +25,9 @@
 
 #include "msg.h"
 #include "net/gnrc/pkt.h"
+#ifdef MODULE_GNRC_SIXLOWPAN_FRAG_HINT
+#include "net/gnrc/sixlowpan/frag/hint.h"
+#endif /* MODULE_GNRC_SIXLOWPAN_FRAG_HINT */
 
 #ifdef __cplusplus
 extern "C" {

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

@@ -0,0 +1,100 @@
+/*
+ * 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/fb.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);
+
+/**
+ * @brief   Fragments a packet with just the IPHC (and padding payload to get
+ *          to 8 byte) as the first fragment
+ *
+ * @pre `(frag_msg != NULL)`
+ * @pre `(pkt != NULL) && (pkt->type == GNRC_NETTYPE_NETIF)`
+ * @pre `(pkt->next != NULL) && (pkt->next->type == GNRC_NETTYPE_SIXLOWPAN)`
+ *
+ * @param[in] pkt                   The compressed packet to be sent. Must be in
+ *                                  send order with a packet snip of type
+ *                                  @ref GNRC_NETTYPE_NETIF first,
+ *                                  @ref GNRC_NETTYPE_SIXLOWPAN (the IPHC
+ *                                  header including NHC) second, and 0 or more
+ *                                  snips of payload.
+ * @param[in] orig_datagram_size    The size of the @p pkt before compression
+ *                                  (without @ref GNRC_NETTYPE_NETIF snip).
+ *                                  This can differ from @p frag_msg's
+ *                                  gnrc_sixlowpan_msg_frag_t::datagram_size
+ *                                  as it might just be a fragment in forwarding
+ *                                  that is re-compressed in @p pkt.
+ * @param[in] ipv6_addr             The (uncompressed) destination address of
+ *                                  @p pkt.
+ * @param[in] fbuf                  A fragmentation buffer entry.
+ *
+ * @return  0, when fragmentation was successful
+ * @return  -1, on error. @p pkt is **not** released in that case and *should*
+ *          be handled by normal fragmentation.
+ */
+int gnrc_sixlowpan_frag_minfwd_frag_iphc(gnrc_pktsnip_t *pkt,
+                                         size_t orig_datagram_size,
+                                         const ipv6_addr_t *ipv6_addr,
+                                         gnrc_sixlowpan_frag_fb_t *fbuf);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* NET_GNRC_SIXLOWPAN_FRAG_MINFWD_H */
+/** @} */

sys/include/net/gnrc/sixlowpan/iphc.h

@@ -52,6 +52,12 @@ void gnrc_sixlowpan_iphc_recv(gnrc_pktsnip_t *pkt, void *ctx, unsigned page);
  * @param[in] pkt   A 6LoWPAN frame with an uncompressed IPv6 header to send.
  *                  Will be translated to an 6LoWPAN IPHC frame.
  * @param[in] ctx   Context for the packet. May be NULL.
+ *                  If not NULL it is expected to be of type @ref
+ *                  gnrc_sixlowpan_frag_fb_t to provide initial information for
+ *                  possible fragmentation after compression (see
+ *                  net_gnrc_sixlowpan_frag_hint). This function might change
+ *                  the content of that. Depending on the compile configuration
+ *                  it might be ignored completely.
  * @param[in] page  Current 6Lo dispatch parsing page.
  *
  */

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 +1,122 @@
+/*
+ * 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;
+}
+
+int gnrc_sixlowpan_frag_minfwd_frag_iphc(gnrc_pktsnip_t *pkt,
+                                         size_t orig_datagram_size,
+                                         const ipv6_addr_t *ipv6_dst,
+                                         gnrc_sixlowpan_frag_fb_t *fbuf)
+{
+    gnrc_netif_t *netif;
+    int res = -1;
+
+    assert(fbuf != NULL);
+    assert((pkt != NULL) && (pkt->type == GNRC_NETTYPE_NETIF));
+    assert((pkt->next != NULL) && (pkt->next->type == GNRC_NETTYPE_SIXLOWPAN));
+    netif = gnrc_netif_hdr_get_netif(pkt->data);
+
+    if (!ipv6_addr_is_link_local(ipv6_dst) &&
+        (fbuf->datagram_size > netif->sixlo.max_frag_size)) {
+        fbuf->pkt = pkt;    /* packet might have been rewritten */
+        /* put slack of IPHC in first fragment */
+        fbuf->hint.fragsz = pkt->next->size;
+        fbuf->hint.fragsz_uncomp = orig_datagram_size -
+                                       gnrc_pkt_len(pkt->next->next);
+        gnrc_sixlowpan_frag_send(NULL, fbuf, 0);
+        res = 0;
+    }
+    else {
+        /* we don't forward link-local so free fbuf again */
+        DEBUG("6lo minfwd: link-local address is not forwarded or "
+              "no fragmentation necessary (%u < %u)\n",
+              fbuf->datagram_size, netif->sixlo.max_frag_size);
+        fbuf->pkt = NULL;
+    }
+    return res;
+}
+
+/** @} */