From d6916f87ca5e566786f1a935a7cabba54774bbda Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Sun, 24 Jul 2011 20:22:29 -0600 Subject: dccp: support for the exchange of NN options in established state 1/2 In contrast to static feature negotiation at the begin of a connection, this patch introduces support for exchange of dynamically changing options. Such an update/exchange is necessary in at least two cases: * CCID-2's Ack Ratio (RFC 4341, 6.1.2) which changes during the connection; * Sequence Window values that, as per RFC 4340, 7.5.2, should be sent "as the connection progresses". Both are non-negotiable (NN) features, which means that no new capabilities are negotiated, but rather that changes in known parameters are brought up-to-date at either end. Thse characteristics are reflected by the implementation: * only NN options can be exchanged after connection setup; * an ack is scheduled directly after activation to speed up the update; * CCIDs may request changes to an NN feature even if a negotiation for that feature is already underway: this is required by CCID-2, where changes in cwnd necessitate Ack Ratio changes, such that the previous Ack Ratio (which is still being negotiated) would cause irrecoverable RTO timeouts (thanks to work by Samuel Jero). Signed-off-by: Gerrit Renker Signed-off-by: Samuel Jero Acked-by: Ian McDonald --- net/dccp/dccp.h | 1 + 1 file changed, 1 insertion(+) (limited to 'net/dccp/dccp.h') diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h index 5fdb07229017..583490aaf56f 100644 --- a/net/dccp/dccp.h +++ b/net/dccp/dccp.h @@ -474,6 +474,7 @@ static inline int dccp_ack_pending(const struct sock *sk) return dccp_ackvec_pending(sk) || inet_csk_ack_scheduled(sk); } +extern int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val); extern int dccp_feat_finalise_settings(struct dccp_sock *dp); extern int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq); extern int dccp_feat_insert_opts(struct dccp_sock*, struct dccp_request_sock*, -- cgit v1.2.3