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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2009-01-16 23:36:30 +0000
committerDavid S. Miller <davem@davemloft.net>2009-01-21 14:34:04 -0800
commitf90f92eed74251034f251e3cdf4fa5c4c1f09df0 (patch)
tree85ed44fee79d91d7bf1ebc6624a90e50af46063f /net/dccp/feat.c
parent5cda9364f1fbc330f0d82f534505a8e375d0a66c (diff)
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 <gerrit@erg.abdn.ac.uk> Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/dccp/feat.c')
-rw-r--r--net/dccp/feat.c65
1 files changed, 56 insertions, 9 deletions
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);

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