Hello again,
When running some connectivity tests, I discovered that UDP
communication would not work between my nodes. Looking at the various
printk() in the kernel, I found out that the IPv6 next header field is
not set (set to 0) upon decompression and thus prevented correct
processing of the decompressed packet at the upper layer (IPv6 layer).
When the next header is UDP, IPHC next header compression applies (as
defined in Section 4.1 of RFC6282). The compression code in 6lowpan.c
seems to behave correctly. However, upon decompression code (in
lowpan_process_data()) fails to properly restore/set the next header
field.
I attached a (very small) patch for this issue to this mail. It works
in my configuration and enables the two nodes to communicate. I do not
believe it will introduce any side-effects.
Regards,
Tony
From d3a296699f98a74b560476e3b5baa53aec13302a Mon Sep 17 00:00:00 2001
From: Tony Cheneau <tony.chen...@amnesiak.org>
Date: Mon, 21 May 2012 14:40:24 -0400
Subject: [PATCH 1/1] Next header was not properly set upon decompression of
a UDP header.
---
net/ieee802154/6lowpan.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c
index 34c7dda..079b0e7 100644
--- a/net/ieee802154/6lowpan.c
+++ b/net/ieee802154/6lowpan.c
@@ -936,8 +936,12 @@ lowpan_process_data(struct sk_buff *skb)
/* UDP data uncompression */
if (iphc0 & LOWPAN_IPHC_NH_C)
+ {
if (lowpan_uncompress_udp_header(skb))
goto drop;
+ hdr.nexthdr = UIP_PROTO_UDP;
+ }
+
/* Not fragmented package */
hdr.payload_len = htons(skb->len);
--
1.7.6.5
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