Instead of accounting for all fields of a packet we can think about,
simply peek the header of a packet we're building and ask ieee802154 how
many bytes of payload space we have. This also accounts for security
headers, which were ignored previously.
Signed-off-by: Phoebe Buckheister <phoebe.buckheis...@itwm.fraunhofer.de>
---
net/ieee802154/6lowpan_rtnl.c | 24 ++++++++++++++++--------
1 file changed, 16 insertions(+), 8 deletions(-)
diff --git a/net/ieee802154/6lowpan_rtnl.c b/net/ieee802154/6lowpan_rtnl.c
index 0f5a69e..3e11b46 100644
--- a/net/ieee802154/6lowpan_rtnl.c
+++ b/net/ieee802154/6lowpan_rtnl.c
@@ -256,6 +256,19 @@ lowpan_fragment_xmit(struct sk_buff *skb, u8 *head,
return dev_queue_xmit(frag);
}
+static int lowpan_fragment_plen(struct sk_buff *skb, int extra)
+{
+ struct ieee802154_hdr hdr;
+
+ ieee802154_hdr_peek(skb, &hdr);
+
+ /* calc the nearest payload length(divided to 8) for a fragment with
+ * a given 802.15.4 hdr and additional lowpan headers which fits into
+ * IEEE802154_MTU
+ */
+ return round_down(ieee802154_max_payload(&hdr) - extra, 8);
+}
+
static int
lowpan_skb_fragmentation(struct sk_buff *skb, struct net_device *dev)
{
@@ -277,12 +290,8 @@ lowpan_skb_fragmentation(struct sk_buff *skb, struct
net_device *dev)
head[1] = dgram_size & 0xff;
memcpy(head + 2, &tag, sizeof(tag));
- /* calc the nearest payload length(divided to 8) for first fragment
- * which fits into a IEEE802154_MTU
- */
- frag_plen = round_down(IEEE802154_MTU - header_length -
- LOWPAN_FRAG1_HEAD_SIZE - lowpan_size -
- IEEE802154_MFR_SIZE, 8);
+ frag_plen = lowpan_fragment_plen(skb, LOWPAN_FRAG1_HEAD_SIZE +
+ lowpan_size);
err = lowpan_fragment_xmit(skb, head, header_length,
frag_plen + lowpan_size, 0,
@@ -300,8 +309,7 @@ lowpan_skb_fragmentation(struct sk_buff *skb, struct
net_device *dev)
head[0] &= ~LOWPAN_DISPATCH_FRAG1;
head[0] |= LOWPAN_DISPATCH_FRAGN;
- frag_plen = round_down(IEEE802154_MTU - header_length -
- LOWPAN_FRAGN_HEAD_SIZE - IEEE802154_MFR_SIZE, 8);
+ frag_plen = lowpan_fragment_plen(skb, LOWPAN_FRAGN_HEAD_SIZE);
while (payload_length - offset > 0) {
int len = frag_plen;
--
1.7.9.5
------------------------------------------------------------------------------
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