From f90f92eed74251034f251e3cdf4fa5c4c1f09df0 Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Fri, 16 Jan 2009 23:36:30 +0000 Subject: dccp: Initialisation framework for feature negotiation This initialises feature negotiation from two tables, which are in turn are initialised from sysctls. As a novel feature, specifics of the implementation (e.g. that short seqnos and ECN are not yet available) are advertised for robustness. Signed-off-by: Gerrit Renker Acked-by: Ian McDonald Signed-off-by: David S. Miller --- net/dccp/feat.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 56 insertions(+), 9 deletions(-) (limited to 'net/dccp/feat.c') diff --git a/net/dccp/feat.c b/net/dccp/feat.c index 4152308958ab..67ffac9905f8 100644 --- a/net/dccp/feat.c +++ b/net/dccp/feat.c @@ -1115,23 +1115,70 @@ int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq, return 0; /* ignore FN options in all other states */ } +/** + * dccp_feat_init - Seed feature negotiation with host-specific defaults + * This initialises global defaults, depending on the value of the sysctls. + * These can later be overridden by registering changes via setsockopt calls. + * The last link in the chain is finalise_settings, to make sure that between + * here and the start of actual feature negotiation no inconsistencies enter. + * + * All features not appearing below use either defaults or are otherwise + * later adjusted through dccp_feat_finalise_settings(). + */ int dccp_feat_init(struct sock *sk) { - struct dccp_sock *dp = dccp_sk(sk); - struct dccp_minisock *dmsk = dccp_msk(sk); + struct list_head *fn = &dccp_sk(sk)->dccps_featneg; + u8 on = 1, off = 0; int rc; + struct { + u8 *val; + u8 len; + } tx, rx; + + /* Non-negotiable (NN) features */ + rc = __feat_register_nn(fn, DCCPF_SEQUENCE_WINDOW, 0, + sysctl_dccp_feat_sequence_window); + if (rc) + return rc; + + /* Server-priority (SP) features */ + + /* Advertise that short seqnos are not supported (7.6.1) */ + rc = __feat_register_sp(fn, DCCPF_SHORT_SEQNOS, true, true, &off, 1); + if (rc) + return rc; - INIT_LIST_HEAD(&dmsk->dccpms_pending); /* XXX no longer used */ - INIT_LIST_HEAD(&dmsk->dccpms_conf); /* XXX no longer used */ + /* RFC 4340 12.1: "If a DCCP is not ECN capable, ..." */ + rc = __feat_register_sp(fn, DCCPF_ECN_INCAPABLE, true, true, &on, 1); + if (rc) + return rc; + + /* + * We advertise the available list of CCIDs and reorder according to + * preferences, to avoid failure resulting from negotiating different + * singleton values (which always leads to failure). + * These settings can still (later) be overridden via sockopts. + */ + if (ccid_get_builtin_ccids(&tx.val, &tx.len) || + ccid_get_builtin_ccids(&rx.val, &rx.len)) + return -ENOBUFS; - /* Ack ratio */ - rc = __feat_register_nn(&dp->dccps_featneg, DCCPF_ACK_RATIO, 0, - dp->dccps_l_ack_ratio); + if (!dccp_feat_prefer(sysctl_dccp_feat_tx_ccid, tx.val, tx.len) || + !dccp_feat_prefer(sysctl_dccp_feat_rx_ccid, rx.val, rx.len)) + goto free_ccid_lists; + + rc = __feat_register_sp(fn, DCCPF_CCID, true, false, tx.val, tx.len); + if (rc) + goto free_ccid_lists; + + rc = __feat_register_sp(fn, DCCPF_CCID, false, false, rx.val, rx.len); + +free_ccid_lists: + kfree(tx.val); + kfree(rx.val); return rc; } -EXPORT_SYMBOL_GPL(dccp_feat_init); - int dccp_feat_activate_values(struct sock *sk, struct list_head *fn_list) { struct dccp_sock *dp = dccp_sk(sk); -- cgit v1.2.3