From 254f16e81ff00c68747078225d4e68f0797d4cba Mon Sep 17 00:00:00 2001
From: Martine Lenders <mail@martine-lenders.eu>
Date: Wed, 27 Jun 2018 12:09:58 +0200
Subject: [PATCH] gnrc_sixlowpan_frag: add asynchronous rbuf GC
While the current approach for garbage collection in the 6Lo reassembly
buffer is good for best-effort handling of
*fragmented* packets and nicely RAM saving, it has the problem that
incomplete, huge datagrams can basically DoS a node, if no further
fragmented datagram is received for a while (since the packet buffer is
full and GC is not triggered).
This change adds a asynchronous GC (utilizing the existing
functionality) to the reassembly buffer, so that even if there is no new
fragmented packet received, fragments older than `RBUF_TIMEOUT` will be
removed from the reassembly buffer, freeing up the otherwise wasted
packet buffer space.
---
sys/include/net/gnrc/sixlowpan/frag.h | 17 ++++++++++++++++-
.../sixlowpan/frag/gnrc_sixlowpan_frag.c | 5 +++++
.../gnrc/network_layer/sixlowpan/frag/rbuf.c | 17 +++++++++++++----
.../gnrc/network_layer/sixlowpan/frag/rbuf.h | 5 +++++
.../network_layer/sixlowpan/gnrc_sixlowpan.c | 4 ++++
5 files changed, 43 insertions(+), 5 deletions(-)
diff --git a/sys/include/net/gnrc/sixlowpan/frag.h b/sys/include/net/gnrc/sixlowpan/frag.h
index f557470ebc..b70b3d41ac 100644
--- a/sys/include/net/gnrc/sixlowpan/frag.h
+++ b/sys/include/net/gnrc/sixlowpan/frag.h
@@ -38,10 +38,20 @@
extern "C" {
#endif
+/**
+ * @name Message types
+ * @{
+ */
/**
* @brief Message type for passing one 6LoWPAN fragment down the network stack
*/
-#define GNRC_SIXLOWPAN_MSG_FRAG_SND (0x0225)
+#define GNRC_SIXLOWPAN_MSG_FRAG_SND (0x0225)
+
+/**
+ * @brief Message type for triggering garbage collection reassembly buffer
+ */
+#define GNRC_SIXLOWPAN_MSG_FRAG_GC_RBUF (0x0226)
+/** @} */
/**
* @brief An entry in the 6LoWPAN reassembly buffer.
@@ -114,6 +124,11 @@ void gnrc_sixlowpan_frag_send(gnrc_pktsnip_t *pkt, void *ctx, unsigned page);
*/
void gnrc_sixlowpan_frag_recv(gnrc_pktsnip_t *pkt, void *ctx, unsigned page);
+/**
+ * @brief Garbage collect reassembly buffer.
+ */
+void gnrc_sixlowpan_frag_gc_rbuf(void);
+
#ifdef __cplusplus
}
#endif
diff --git a/sys/net/gnrc/network_layer/sixlowpan/frag/gnrc_sixlowpan_frag.c b/sys/net/gnrc/network_layer/sixlowpan/frag/gnrc_sixlowpan_frag.c
index 6724dc929a..03ac3db6f4 100644
--- a/sys/net/gnrc/network_layer/sixlowpan/frag/gnrc_sixlowpan_frag.c
+++ b/sys/net/gnrc/network_layer/sixlowpan/frag/gnrc_sixlowpan_frag.c
@@ -320,4 +320,9 @@ void gnrc_sixlowpan_frag_recv(gnrc_pktsnip_t *pkt, void *ctx, unsigned page)
gnrc_pktbuf_release(pkt);
}
+void gnrc_sixlowpan_frag_gc_rbuf(void)
+{
+ rbuf_gc();
+}
+
/** @} */
diff --git a/sys/net/gnrc/network_layer/sixlowpan/frag/rbuf.c b/sys/net/gnrc/network_layer/sixlowpan/frag/rbuf.c
index 8aef46371a..ba855a9586 100644
--- a/sys/net/gnrc/network_layer/sixlowpan/frag/rbuf.c
+++ b/sys/net/gnrc/network_layer/sixlowpan/frag/rbuf.c
@@ -48,6 +48,9 @@ static rbuf_t rbuf[RBUF_SIZE];
static char l2addr_str[3 * IEEE802154_LONG_ADDRESS_LEN];
+static xtimer_t _gc_timer;
+static msg_t _gc_timer_msg = { .type = GNRC_SIXLOWPAN_MSG_FRAG_GC_RBUF };
+
/* ------------------------------------
* internal function definitions
* ------------------------------------*/
@@ -59,8 +62,6 @@ static rbuf_int_t *_rbuf_int_get_free(void);
static void _rbuf_rem(rbuf_t *entry);
/* update interval buffer of entry */
static bool _rbuf_update_ints(rbuf_t *entry, uint16_t offset, size_t frag_size);
-/* checks timeouts and removes entries if necessary (oldest if full) */
-static void _rbuf_gc(void);
/* gets an entry identified by its tupel */
static rbuf_t *_rbuf_get(const void *src, size_t src_len,
const void *dst, size_t dst_len,
@@ -78,7 +79,7 @@ void rbuf_add(gnrc_netif_hdr_t *netif_hdr, gnrc_pktsnip_t *pkt,
rbuf_int_t *ptr;
uint8_t *data = ((uint8_t *)pkt->data) + sizeof(sixlowpan_frag_t);
- _rbuf_gc();
+ rbuf_gc();
entry = _rbuf_get(gnrc_netif_hdr_get_src_addr(netif_hdr), netif_hdr->src_l2addr_len,
gnrc_netif_hdr_get_dst_addr(netif_hdr), netif_hdr->dst_l2addr_len,
byteorder_ntohs(frag->disp_size) & SIXLOWPAN_FRAG_SIZE_MASK,
@@ -246,7 +247,7 @@ static bool _rbuf_update_ints(rbuf_t *entry, uint16_t offset, size_t frag_size)
return true;
}
-static void _rbuf_gc(void)
+void rbuf_gc(void)
{
uint32_t now_usec = xtimer_now_usec();
unsigned int i;
@@ -271,6 +272,11 @@ static void _rbuf_gc(void)
}
}
+static inline void _set_rbuf_timeout(void)
+{
+ xtimer_set_msg(&_gc_timer, RBUF_TIMEOUT, &_gc_timer_msg, sched_active_pid);
+}
+
static rbuf_t *_rbuf_get(const void *src, size_t src_len,
const void *dst, size_t dst_len,
size_t size, uint16_t tag)
@@ -295,6 +301,7 @@ static rbuf_t *_rbuf_get(const void *src, size_t src_len,
l2addr_str),
(unsigned)rbuf[i].super.pkt->size, rbuf[i].super.tag);
rbuf[i].arrival = now_usec;
+ _set_rbuf_timeout();
return &(rbuf[i]);
}
@@ -347,6 +354,8 @@ static rbuf_t *_rbuf_get(const void *src, size_t src_len,
l2addr_str), (unsigned)res->super.pkt->size,
res->super.tag);
+ _set_rbuf_timeout();
+
return res;
}
diff --git a/sys/net/gnrc/network_layer/sixlowpan/frag/rbuf.h b/sys/net/gnrc/network_layer/sixlowpan/frag/rbuf.h
index 405e424052..d2ad4b815b 100644
--- a/sys/net/gnrc/network_layer/sixlowpan/frag/rbuf.h
+++ b/sys/net/gnrc/network_layer/sixlowpan/frag/rbuf.h
@@ -85,6 +85,11 @@ typedef struct {
void rbuf_add(gnrc_netif_hdr_t *netif_hdr, gnrc_pktsnip_t *frag,
size_t frag_size, size_t offset);
+/**
+ * @brief Checks timeouts and removes entries if necessary
+ */
+void rbuf_gc(void);
+
#ifdef __cplusplus
}
#endif
diff --git a/sys/net/gnrc/network_layer/sixlowpan/gnrc_sixlowpan.c b/sys/net/gnrc/network_layer/sixlowpan/gnrc_sixlowpan.c
index 18c615851c..0b947b9f9f 100644
--- a/sys/net/gnrc/network_layer/sixlowpan/gnrc_sixlowpan.c
+++ b/sys/net/gnrc/network_layer/sixlowpan/gnrc_sixlowpan.c
@@ -375,6 +375,10 @@ static void *_event_loop(void *args)
DEBUG("6lo: send fragmented event received\n");
gnrc_sixlowpan_frag_send(NULL, msg.content.ptr, 0);
break;
+ case GNRC_SIXLOWPAN_MSG_FRAG_GC_RBUF:
+ DEBUG("6lo: garbage collect reassembly buffer event received\n");
+ gnrc_sixlowpan_frag_gc_rbuf();
+ break;
#endif
default:
--
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