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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2008-09-04 01:30:19 -0400
committerGerrit Renker <gerrit@erg.abdn.ac.uk>2008-09-04 01:45:37 -0400
commit68b1de15765f2b0e0925e692dab2b2fa2abd93fc (patch)
tree893594a088a7d9ba4bff6c1820ec014740ca62bf /net/dccp/input.c
parentd7dc7e5f49299739e610ea8febf9ea91a4dc1ae9 (diff)
dccp ccid-2: Algorithm to update buffer state
This provides a routine to consistently update the buffer state when the peer acknowledges receipt of Ack Vectors; updating state in the list of Ack Vectors as well as in the circular buffer. While based on RFC 4340, several additional (and necessary) precautions were added to protect the consistency of the buffer state. These additions are essential, since analysis and experience showed that the basic algorithm was insufficient for this task (which lead to problems that were hard to debug). The algorithm now * deals with HC-sender acknowledging to HC-receiver and vice versa, * keeps track of the last unacknowledged but received seqno in tail_ackno, * has special cases to reset the overflow condition when appropriate, * is protected against receiving older information (would mess up buffer state). Note: The older code performed an unnecessary step, where the sender cleared Ack Vector state by parsing the Ack Vector received by the HC-receiver. Doing this was entirely redundant, since * the receiver always puts the full acknowledgment window (groups 2,3 in 11.4.2) into the Ack Vectors it sends; hence the HC-receiver is only interested in the highest state that the HC-sender received; * this means that the acknowledgment number on the (Data)Ack from the HC-sender is sufficient; and work done in parsing earlier state is not necessary, since the later state subsumes the earlier one (see also RFC 4340, A.4). This older interface (dccp_ackvec_parse()) is therefore removed. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Diffstat (limited to 'net/dccp/input.c')
-rw-r--r--net/dccp/input.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/dccp/input.c b/net/dccp/input.c
index 70ad0ba72146..77a5d57ab702 100644
--- a/net/dccp/input.c
+++ b/net/dccp/input.c
@@ -164,8 +164,8 @@ static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
164 struct dccp_sock *dp = dccp_sk(sk); 164 struct dccp_sock *dp = dccp_sk(sk);
165 165
166 if (dp->dccps_hc_rx_ackvec != NULL) 166 if (dp->dccps_hc_rx_ackvec != NULL)
167 dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk, 167 dccp_ackvec_clear_state(dp->dccps_hc_rx_ackvec,
168 DCCP_SKB_CB(skb)->dccpd_ack_seq); 168 DCCP_SKB_CB(skb)->dccpd_ack_seq);
169} 169}
170 170
171static void dccp_deliver_input_to_ccids(struct sock *sk, struct sk_buff *skb) 171static void dccp_deliver_input_to_ccids(struct sock *sk, struct sk_buff *skb)