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[DCCP]: Remove ambiguity in the way before48 is used

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This removes two ambiguities in employing the new definition of before48,
following the analysis on http://www.mail-archive.com/dccp@vger.kernel.org/msg01295.html

 (1) Updating GSR when P.seqno >= S.SWL
     With the old definition we did not update when P.seqno and S.SWL are 2^47 apart. To
     ensure the same behaviour as with the old definition, this is replaced with the
     equivalent condition dccp_delta_seqno(S.SWL, P.seqno) >= 0

 (2) Sending SYNC when P.seqno >= S.OSR
     Here it is debatable whether the new definition causes an ambiguity: the case is
     similar to (1); and to have consistency with the case (1), we use the equivalent
     condition dccp_delta_seqno(S.OSR, P.seqno) >= 0

Detailed Justification
This commit is contained in:
Gerrit Renker 2007-03-20 13:08:19 -03:00 committed by David S. Miller
parent b16be51b5e
commit 8d13bf9a0b
1 changed files with 4 additions and 2 deletions
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6
net/dccp/input.c
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@ -86,7 +86,8 @@ static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
dh->dccph_type == DCCP_PKT_SYNCACK) {
if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
dp->dccps_awl, dp->dccps_awh) &&
!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl))
dccp_delta_seqno(dp->dccps_swl,
DCCP_SKB_CB(skb)->dccpd_seq) >= 0)
dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
else
return -1;
@ -203,7 +204,8 @@ static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
if (dp->dccps_role != DCCP_ROLE_CLIENT)
goto send_sync;
check_seq:
if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) {
if (dccp_delta_seqno(dp->dccps_osr,
DCCP_SKB_CB(skb)->dccpd_seq) >= 0) {
send_sync:
dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
DCCP_PKT_SYNC);