Commit 8d13bf9a authored Mar 20, 2007 by Gerrit Renker Committed by David S. Miller Apr 25, 2007

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

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

parent b16be51b

net/dccp/input.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -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);

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