This initialises feature negotiation from two tables, which are initialised

from sysctls.
As a novel feature, specifics of the implementation (e.g. currently short

seqnos and ECN are not supported) are advertised for robustness.
Signed-off-by: Gerrit Renker

Acked-by: Ian McDonald

---

 include/linux/dccp.h |   19 --------------

 net/dccp/feat.c      |   66 ++++++++++++++++++++++++++++++++++++++++++-------

 net/dccp/feat.h      |    2 +-

 3 files changed, 57 insertions(+), 30 deletions(-)
--- a/include/linux/dccp.h

+++ b/include/linux/dccp.h

@@ -369,28 +369,9 @@ static inline unsigned int dccp_hdr_len(const struct sk_buff *skb)

   * 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

@@ -1122,24 +1122,70 @@ 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);

-out:

+	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);

--- a/net/dccp/feat.h

+++ b/net/dccp/feat.h

@@ -110,13 +110,13 @@ static inline void dccp_feat_debug(const u8 type, const u8 feat, const u8 val)

 #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.

--

1.6.0.rc2
--

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