From 7452f48c2608d73d715aeeba23c8b5f2d8c49c0a Mon Sep 17 00:00:00 2001
From: Martine Lenders <mail@martine-lenders.eu>
Date: Sun, 30 Dec 2018 13:35:04 +0100
Subject: [PATCH] gnrc_sixlowpan_frag: unroll recursion
While the recursion in `gnrc_sixlowpan_frag` shouldn't be infinite we
still should avoid using recursions in general (also to be able to
statically analyze stack usage). This unrolls the recursion.
---
.../gnrc/network_layer/sixlowpan/frag/rbuf.c | 31 ++++++++++++++-----
1 file changed, 24 insertions(+), 7 deletions(-)
diff --git a/sys/net/gnrc/network_layer/sixlowpan/frag/rbuf.c b/sys/net/gnrc/network_layer/sixlowpan/frag/rbuf.c
index 8edb73b053..3e98b52c59 100644
--- a/sys/net/gnrc/network_layer/sixlowpan/frag/rbuf.c
+++ b/sys/net/gnrc/network_layer/sixlowpan/frag/rbuf.c
@@ -64,9 +64,27 @@ static bool _rbuf_update_ints(rbuf_t *entry, uint16_t offset, size_t frag_size);
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, unsigned page);
+/* internal add to repeat add when fragments overlapped */
+static int _rbuf_add(gnrc_netif_hdr_t *netif_hdr, gnrc_pktsnip_t *pkt,
+ size_t offset, unsigned page);
+
+/* status codes for _rbuf_add() */
+enum {
+ RBUF_ADD_SUCCESS,
+ RBUF_ADD_ERROR,
+ RBUF_ADD_REPEAT,
+};
void rbuf_add(gnrc_netif_hdr_t *netif_hdr, gnrc_pktsnip_t *pkt,
size_t offset, unsigned page)
+{
+ if (_rbuf_add(netif_hdr, pkt, offset, page) == RBUF_ADD_REPEAT) {
+ _rbuf_add(netif_hdr, pkt, offset, page);
+ }
+}
+
+static int _rbuf_add(gnrc_netif_hdr_t *netif_hdr, gnrc_pktsnip_t *pkt,
+ size_t offset, unsigned page)
{
rbuf_t *entry;
sixlowpan_frag_t *frag = pkt->data;
@@ -83,7 +101,7 @@ void rbuf_add(gnrc_netif_hdr_t *netif_hdr, gnrc_pktsnip_t *pkt,
if (entry == NULL) {
DEBUG("6lo rbuf: reassembly buffer full.\n");
gnrc_pktbuf_release(pkt);
- return;
+ return RBUF_ADD_ERROR;
}
ptr = entry->ints;
@@ -104,7 +122,7 @@ void rbuf_add(gnrc_netif_hdr_t *netif_hdr, gnrc_pktsnip_t *pkt,
DEBUG("6lo rfrag: fragment too big for resulting datagram, discarding datagram\n");
gnrc_pktbuf_release(entry->super.pkt);
rbuf_rm(entry);
- return;
+ return RBUF_ADD_ERROR;
}
/* If the fragment overlaps another fragment and differs in either the size
@@ -119,9 +137,7 @@ void rbuf_add(gnrc_netif_hdr_t *netif_hdr, gnrc_pktsnip_t *pkt,
/* "A fresh reassembly may be commenced with the most recently
* received link fragment"
* https://tools.ietf.org/html/rfc4944#section-5.3 */
- rbuf_add(netif_hdr, pkt, offset, page);
-
- return;
+ return RBUF_ADD_REPEAT;
}
ptr = ptr->next;
@@ -139,10 +155,10 @@ void rbuf_add(gnrc_netif_hdr_t *netif_hdr, gnrc_pktsnip_t *pkt,
gnrc_pktbuf_release(entry->super.pkt);
gnrc_pktbuf_release(pkt);
rbuf_rm(entry);
- return;
+ return RBUF_ADD_ERROR;
}
gnrc_sixlowpan_iphc_recv(pkt, &entry->super, 0);
- return;
+ return RBUF_ADD_SUCCESS;
}
else
#endif
@@ -155,6 +171,7 @@ void rbuf_add(gnrc_netif_hdr_t *netif_hdr, gnrc_pktsnip_t *pkt,
}
gnrc_sixlowpan_frag_rbuf_dispatch_when_complete(&entry->super, netif_hdr);
gnrc_pktbuf_release(pkt);
+ return RBUF_ADD_SUCCESS;
}
static inline bool _rbuf_int_overlap_partially(rbuf_int_t *i, uint16_t start, uint16_t end)
--
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