Date: Tue, 14 Feb 2012 18:36:17 GMT From: Monthadar <monthadar@gmail.com> To: freebsd-gnats-submit@FreeBSD.org Subject: kern/165146: Net802.11 Fragment number is assigned 1 (should be 0) when fragmenting a frame Message-ID: <201202141836.q1EIaHDL018231@red.freebsd.org> Resent-Message-ID: <201202141840.q1EIeAan094901@freefall.freebsd.org>
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>Number: 165146 >Category: kern >Synopsis: Net802.11 Fragment number is assigned 1 (should be 0) when fragmenting a frame >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Tue Feb 14 18:40:10 UTC 2012 >Closed-Date: >Last-Modified: >Originator: Monthadar >Release: Current >Organization: >Environment: effects all enviroments >Description: I found that in FreeBSD current the first fragment will have a fragment number = 1 in function ieee80211_fragment. But according to 802.11-2007, 9.4 Fragmentation page 279: "...The fragments shall be sent in order of lowest fragment number to highest fragment number, where the fragment number value starts at zero, ..." This also holds on the 802.11-2011 draft 12: "The fragment number is set to 0 in the first or only fragment of an MSDU or MMPDU and is incremented by one for each successive fragment of that MSDU or MMPDU." I checked Linux 3.3-rc3 code and there I see them having a check on rx side if (frag == 0) { /* This is the first fragment of a new frame. */ and on tx side they put: fragnum = 0; On Madwifi 0.9.4 in function ieee80211_encap: fragnum = 0; >How-To-Repeat: N/A >Fix: Patch attached with submission follows: >From 32927dd6a2271488b52dd05b3d89ca193961ffa1 Mon Sep 17 00:00:00 2001 From: Monthadar Al Jaberi <monthadar@gmail.com> Date: Tue, 14 Feb 2012 19:28:32 +0100 Subject: [PATCH] Fragment number for the first fragment should be zero as specified in the 802.11-2007 standard. --- sys/net80211/ieee80211_output.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/sys/net80211/ieee80211_output.c b/sys/net80211/ieee80211_output.c index f6f90b6..6cb1f94 100644 --- a/sys/net80211/ieee80211_output.c +++ b/sys/net80211/ieee80211_output.c @@ -1377,7 +1377,7 @@ ieee80211_fragment(struct ieee80211vap *vap, struct mbuf *m0, /* NB: mark the first frag; it will be propagated below */ wh->i_fc[1] |= IEEE80211_FC1_MORE_FRAG; totalhdrsize = hdrsize + ciphdrsize; - fragno = 1; + fragno = 0; off = mtu - ciphdrsize; remainder = m0->m_pkthdr.len - off; prev = m0; -- 1.7.8 >Release-Note: >Audit-Trail: >Unformatted:
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