From b3d14bff12a38ad13a174eb0cc83d2ac7169eee4 Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Wed, 10 Nov 2010 21:21:35 +0100 Subject: dccp ccid-2: Implementation of circular Ack Vector buffer with overflow handling This completes the implementation of a circular buffer for Ack Vectors, by extending the current (linear array-based) implementation. The changes are: (a) An `overflow' flag to deal with the case of overflow. As before, dynamic growth of the buffer will not be supported; but code will be added to deal robustly with overflowing Ack Vector buffers. (b) A `tail_seqno' field. When naively implementing the algorithm of Appendix A in RFC 4340, problems arise whenever subsequent Ack Vector records overlap, which can bring the entire run length calculation completely out of synch. (This is documented on http://www.erg.abdn.ac.uk/users/gerrit/dccp/notes/\ ack_vectors/tracking_tail_ackno/ .) (c) The buffer length is now computed dynamically (i.e. current fill level), as the span between head to tail. As a result, dccp_ackvec_pending() is now simpler - the #ifdef is no longer necessary since buf_empty is always true when IP_DCCP_ACKVEC is not configured. Signed-off-by: Gerrit Renker --- net/dccp/options.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'net/dccp/options.c') diff --git a/net/dccp/options.c b/net/dccp/options.c index f4ff0a308269..5adeeed5e0d2 100644 --- a/net/dccp/options.c +++ b/net/dccp/options.c @@ -429,9 +429,10 @@ static int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb) { struct dccp_sock *dp = dccp_sk(sk); struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec; + const u16 buflen = dccp_ackvec_buflen(av); /* Figure out how many options do we need to represent the ackvec */ - const u8 nr_opts = DIV_ROUND_UP(av->av_vec_len, DCCP_SINGLE_OPT_MAXLEN); - u16 len = av->av_vec_len + 2 * nr_opts; + const u8 nr_opts = DIV_ROUND_UP(buflen, DCCP_SINGLE_OPT_MAXLEN); + u16 len = buflen + 2 * nr_opts; u8 i, nonce = 0; const unsigned char *tail, *from; unsigned char *to; @@ -442,7 +443,7 @@ static int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb) DCCP_SKB_CB(skb)->dccpd_opt_len += len; to = skb_push(skb, len); - len = av->av_vec_len; + len = buflen; from = av->av_buf + av->av_buf_head; tail = av->av_buf + DCCPAV_MAX_ACKVEC_LEN; @@ -580,8 +581,7 @@ int dccp_insert_options(struct sock *sk, struct sk_buff *skb) if (dccp_insert_option_timestamp(skb)) return -1; - } else if (dp->dccps_hc_rx_ackvec != NULL && - dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) && + } else if (dccp_ackvec_pending(sk) && dccp_insert_option_ackvec(sk, skb)) { return -1; } -- cgit v1.2.3