diff options
| author | Gerrit Renker <gerrit@erg.abdn.ac.uk> | 2008-09-04 07:30:19 +0200 |
|---|---|---|
| committer | Gerrit Renker <gerrit@erg.abdn.ac.uk> | 2008-09-04 07:45:32 +0200 |
| commit | 624a965a93610152b10c73d050ed44812efa8abe (patch) | |
| tree | 50ad65253183b9140ff6f8a3ef43cdeb1b8feb9f /net/dccp/dccp.h | |
| parent | 76f738a7950b559a23ab3c692c99a02f35a54f7f (diff) | |
dccp: Support for the exchange of NN options in established state
In contrast to static feature negotiation at the begin of a connection, which
establishes the capabilities of both endpoints, this patch introduces support
for dynamic exchange of feature negotiation options.
Such a dynamic 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
as the connection progresses".
Both are NN (non-negotiable) features. Hence dynamic feature "negotiation" is
distinguished from static/pre-connection negotiation by the following:
* no new capabilities are negotiated (those that matter for the connection
are negotiated prior to setting up the connection, comparable to SIP);
* features must be understood by each endpoint: as per RFC 4340, 6.4,
Sequence Window is "Req'd" and Ack Ratio must be understood when CCID-2
is used as per the note underneath Table 4.
These characteristics are reflected in the implementation:
* only NN options can be exchanged after connection setup;
* NN options are activated directly after validating them. The rationale is
that a peer must accept every valid NN value (RFC 4340, 6.3.2), hence it
will either accept the value and send a "Confirm R", or it will send an
empty Confirm (which will reset the connection according to FN rules).
* An Ack is scheduled directly after activation to accelerate communicating
the update to the peer.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Diffstat (limited to 'net/dccp/dccp.h')
| -rw-r--r-- | net/dccp/dccp.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h index 94ae6d41d72..0a07b2e24e6 100644 --- a/net/dccp/dccp.h +++ b/net/dccp/dccp.h @@ -436,6 +436,7 @@ static inline int dccp_ack_pending(const struct sock *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*, |