gnrc_ipv6_ext_frag: Initial import of IPv6 reassembly

Makefile.dep

@@ -264,6 +264,11 @@ ifneq (,$(filter gnrc_rpl_srh,$(USEMODULE)))
   USEMODULE += gnrc_ipv6_ext_rh
 endif
 
+ifneq (,$(filter gnrc_ipv6_ext_frag,$(USEMODULE)))
+  USEMODULE += gnrc_ipv6_ext
+  USEMODULE += xtimer
+endif
+
 ifneq (,$(filter gnrc_ipv6_ext_rh,$(USEMODULE)))
   USEMODULE += gnrc_ipv6_ext
 endif

sys/include/net/gnrc/ipv6/ext.h

@@ -29,6 +29,7 @@
 
 #include "net/gnrc/pkt.h"
 #include "net/ipv6/ext.h"
+#include "timex.h"
 
 #ifdef MODULE_GNRC_IPV6_EXT_RH
 #include "net/gnrc/ipv6/ext/rh.h"
@@ -38,6 +39,45 @@
 extern "C" {
 #endif
 
+/**
+ * @defgroup    net_gnrc_ipv6_ext_conf IPv6 extension header compile configurations
+ * @ingroup     net_gnrc_ipv6_ext
+ * @ingroup     config
+ * @{
+ */
+/**
+ * @brief   IPv6 fragmentation reassembly buffer size
+ *
+ * This limits the total amount of datagrams that can be reassembled at the same time.
+ *
+ * @note    Only applicable with [gnrc_ipv6_ext_frag](@ref net_gnrc_ipv6_ext_frag) module
+ */
+#ifndef GNRC_IPV6_EXT_FRAG_RBUF_SIZE
+#define GNRC_IPV6_EXT_FRAG_RBUF_SIZE        (1U)
+#endif
+
+/**
+ * @brief   The number of total allocatable @ref gnrc_ipv6_ext_frag_limits_t objects
+ *
+ * This is the maximum number of receivable fragments, shared between all
+ * fragmented datagrams
+ *
+ * @note    Only applicable with [gnrc_ipv6_ext_frag](@ref net_gnrc_ipv6_ext_frag) module
+ */
+#ifndef GNRC_IPV6_EXT_FRAG_LIMITS_POOL_SIZE
+#define GNRC_IPV6_EXT_FRAG_LIMITS_POOL_SIZE (GNRC_IPV6_EXT_FRAG_RBUF_SIZE * 2U)
+#endif
+
+/**
+ * @brief   Timeout for IPv6 fragmentation reassembly buffer entries in microseconds
+ *
+ * @note    Only applicable with [gnrc_ipv6_ext_frag](@ref net_gnrc_ipv6_ext_frag) module
+ */
+#ifndef GNRC_IPV6_EXT_FRAG_RBUF_TIMEOUT_US
+#define GNRC_IPV6_EXT_FRAG_RBUF_TIMEOUT_US  (10U * US_PER_SEC)
+#endif
+/** @} **/
+
 /**
  * @brief   Builds an extension header for sending.
  *

sys/include/net/gnrc/ipv6/ext/frag.h

@@ -0,0 +1,147 @@
+/*
+ * 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_ipv6_ext_frag Support for IPv6 fragmentation extension
+ * @ingroup     net_gnrc_ipv6_ext
+ * @brief       GNRC implementation of IPv6 fragmentation extension
+ * @{
+ *
+ * @file
+ * @brief   GNRC fragmentation extension definitions
+ *
+ * @author  Martine Lenders <[email protected]>
+ */
+#ifndef NET_GNRC_IPV6_EXT_FRAG_H
+#define NET_GNRC_IPV6_EXT_FRAG_H
+
+#include <stdint.h>
+
+#include "clist.h"
+#include "net/gnrc/pkt.h"
+#include "net/gnrc/pktbuf.h"
+#include "net/ipv6/hdr.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief   Message type to time reassembly buffer garbage collection
+ */
+#define GNRC_IPV6_EXT_FRAG_RBUF_GC  (0xfe00U)
+
+/**
+ * @brief   Data type to describe limits of a single fragment in the reassembly
+ *          buffer
+ */
+typedef struct gnrc_ipv6_ext_frag_limits {
+    struct gnrc_ipv6_ext_frag_limits *next; /**< limits of next fragment */
+    uint16_t start;                         /**< the start (= offset) of the fragment */
+    uint16_t end;                           /**< the exclusive end (= offset + length) of the
+                                             *   fragment */
+} gnrc_ipv6_ext_frag_limits_t;
+
+/**
+ * @brief   A reassembly buffer entry
+ */
+typedef struct {
+    gnrc_pktsnip_t *pkt;    /**< the (partly) reassembled packet */
+    ipv6_hdr_t *ipv6;       /**< the IPv6 header of gnrc_ipv6_ext_frag_rbuf_t::pkt */
+    /**
+     * @brief   The limits of the fragments in the reassembled packet
+     *
+     * @note    Members of this list can be cast to gnrc_ipv6_ext_frag_limits_t.
+     */
+    clist_node_t limits;
+    uint32_t id;            /**< the identification from the fragment headers */
+    uint32_t arrival;       /**< arrival time of last received fragment */
+    uint16_t pkt_len;       /**< length of gnrc_ipv6_ext_frag_rbuf_t::pkt */
+    uint8_t last;           /**< received last fragment */
+} gnrc_ipv6_ext_frag_rbuf_t;
+
+/**
+ * @brief   Initializes IPv6 fragmentation and reassembly
+ * @internal
+ */
+void gnrc_ipv6_ext_frag_init(void);
+
+/**
+ * @brief   Reassemble fragmented IPv6 packet
+ *
+ * @param[in] pkt   A fragment of the IPv6 packet to be reassembled containing
+ *                  the fragment header in the first snip.
+ *
+ * @return  The reassembled packet when @p pkt completed the reassembly
+ * @return  NULL, when there are still fragments missing or an error occured
+ *          during reassembly
+ */
+gnrc_pktsnip_t *gnrc_ipv6_ext_frag_reass(gnrc_pktsnip_t *pkt);
+
+/**
+ * @name    Reassembly buffer operations
+ * @{
+ */
+/**
+ * @brief   Get a reassembly buffer by the identifying parameters
+ *
+ * @internal
+ * @see     [RFC 8200, section 4.5](https://tools.ietf.org/html/rfc8200#section-4.5)
+ *
+ * @param[in] hdr   IPv6 header to get source and destination address from.
+ * @param[in] id    The identification from the fragment header.
+ *
+ * @return  A reassembly buffer matching @p id ipv6_hdr_t::src and ipv6_hdr::dst
+ *          of @p hdr or first free reassembly buffer. Will never be NULL, as
+ *          in the case of the reassembly buffer being full, the entry with the
+ *          lowest gnrc_ipv6_ext_frag_rbuf_t::arrival (serial-number-like) is
+ *          removed.
+ */
+gnrc_ipv6_ext_frag_rbuf_t *gnrc_ipv6_ext_frag_rbuf_get(ipv6_hdr_t *ipv6,
+                                                       uint32_t id);
+
+/**
+ * @brief   Frees a reassembly buffer entry (but does not release its
+ *          gnrc_ipv6_ext_frag_rbuf_t::pkt)
+ *
+ * @param[in] rbuf  A reassembly buffer entry.
+ */
+void gnrc_ipv6_ext_frag_rbuf_free(gnrc_ipv6_ext_frag_rbuf_t *rbuf);
+
+/**
+ * @brief   Delete a reassembly buffer entry (and release its
+ *          gnrc_ipv6_ext_frag_rbuf_t::pkt)
+ *
+ * @note    May be used by the IPv6 thread to remove a timed out reassembly
+ *          buffer entry.
+ *
+ * @param[in] rbuf  A reassembly buffer entry.
+ */
+static inline void gnrc_ipv6_ext_frag_rbuf_del(gnrc_ipv6_ext_frag_rbuf_t *rbuf)
+{
+    gnrc_pktbuf_release(rbuf->pkt);
+    rbuf->pkt = NULL;
+    gnrc_ipv6_ext_frag_rbuf_free(rbuf);
+}
+
+/**
+ * @brief   Garbage-collect reassembly buffer
+ *
+ * This calls @ref gnrc_ipv6_ext_frag_rbuf_del() for all reassembly buffer
+ * entries for which * gnrc_ipv6_ext_frag_rbuf_t::arrival is
+ * @ref GNRC_IPV6_EXT_FRAG_RBUF_TIMEOUT_US in the past.
+ */
+void gnrc_ipv6_ext_frag_rbuf_gc(void);
+/** @} */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* NET_GNRC_IPV6_EXT_FRAG_H */
+/** @} */

sys/net/gnrc/Makefile

@@ -13,6 +13,9 @@ endif
 ifneq (,$(filter gnrc_ipv6_ext,$(USEMODULE)))
   DIRS += network_layer/ipv6/ext
 endif
+ifneq (,$(filter gnrc_ipv6_ext_frag,$(USEMODULE)))
+  DIRS += network_layer/ipv6/ext/frag
+endif
 ifneq (,$(filter gnrc_ipv6_ext_rh,$(USEMODULE)))
   DIRS += network_layer/ipv6/ext/rh
 endif

sys/net/gnrc/network_layer/ipv6/ext/frag/Makefile

@@ -0,0 +1,3 @@
+MODULE := gnrc_ipv6_ext_frag
+
+include $(RIOTBASE)/Makefile.base