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Message-Id: <1232184993-9927-2-git-send-email-gerrit@erg.abdn.ac.uk>
Date: Sat, 17 Jan 2009 10:36:30 +0100
From: Gerrit Renker <gerrit@....abdn.ac.uk>
To: davem@...emloft.net
Cc: dccp@...r.kernel.org, netdev@...r.kernel.org,
Gerrit Renker <gerrit@....abdn.ac.uk>
Subject: [PATCH 1/4] 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@....abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@...di.co.nz>
---
include/linux/dccp.h | 19 --------------
net/dccp/feat.c | 67 +++++++++++++++++++++++++++++++++++++++++++--------
net/dccp/feat.h | 2 -
3 files changed, 58 insertions(+), 30 deletions(-)
--- a/net/dccp/feat.h
+++ b/net/dccp/feat.h
@@ -113,13 +113,13 @@ static inline void dccp_feat_debug(const
#define dccp_feat_debug(type, feat, val)
#endif /* CONFIG_IP_DCCP_DEBUG */
+extern int dccp_feat_init(struct sock *sk);
extern int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
u8 const *list, u8 len);
extern int dccp_feat_register_nn(struct sock *sk, u8 feat, u64 val);
extern int dccp_feat_parse_options(struct sock *, struct dccp_request_sock *,
u8 mand, u8 opt, u8 feat, u8 *val, u8 len);
extern int dccp_feat_clone_list(struct list_head const *, struct list_head *);
-extern int dccp_feat_init(struct sock *sk);
/*
* Encoding variable-length options and their maximum length.
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -369,28 +369,9 @@ static inline unsigned int dccp_hdr_len(
* Will be used to pass the state from dccp_request_sock to dccp_sock.
*
* @dccpms_sequence_window - Sequence Window Feature (section 7.5.2)
- * @dccpms_pending - List of features being negotiated
- * @dccpms_conf -
*/
struct dccp_minisock {
__u64 dccpms_sequence_window;
- struct list_head dccpms_pending;
- struct list_head dccpms_conf;
-};
-
-struct dccp_opt_conf {
- __u8 *dccpoc_val;
- __u8 dccpoc_len;
-};
-
-struct dccp_opt_pend {
- struct list_head dccpop_node;
- __u8 dccpop_type;
- __u8 dccpop_feat;
- __u8 *dccpop_val;
- __u8 dccpop_len;
- int dccpop_conf;
- struct dccp_opt_conf *dccpop_sc;
};
extern void dccp_minisock_init(struct dccp_minisock *dmsk);
--- a/net/dccp/feat.c
+++ b/net/dccp/feat.c
@@ -1115,23 +1115,70 @@ int dccp_feat_parse_options(struct sock
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;
+
+ /* 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;
- INIT_LIST_HEAD(&dmsk->dccpms_pending); /* XXX no longer used */
- INIT_LIST_HEAD(&dmsk->dccpms_conf); /* XXX no longer used */
-
- /* Ack ratio */
- rc = __feat_register_nn(&dp->dccps_featneg, DCCPF_ACK_RATIO, 0,
- dp->dccps_l_ack_ratio);
+ /*
+ * 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;
+
+ 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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