/*
* net/dccp/feat.h
*
- * An implementation of the DCCP protocol
+ * Feature negotiation for the DCCP protocol (RFC 4340, section 6)
+ * Copyright (c) 2008 Gerrit Renker <gerrit@erg.abdn.ac.uk>
* Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
*
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
*/
-
#include <linux/types.h>
#include "dccp.h"
-static inline int dccp_feat_is_valid_length(u8 type, u8 feature, u8 len)
-{
- /* sec. 6.1: Confirm has at least length 3,
- * sec. 6.2: Change has at least length 4 */
- if (len < 3)
- return 1;
- if (len < 4 && (type == DCCPO_CHANGE_L || type == DCCPO_CHANGE_R))
- return 1;
- /* XXX: add per-feature length validation (sec. 6.6.8) */
- return 0;
-}
+/*
+ * Known limit values
+ */
+/* Ack Ratio takes 2-byte integer values (11.3) */
+#define DCCPF_ACK_RATIO_MAX 0xFFFF
+/* Wmin=32 and Wmax=2^46-1 from 7.5.2 */
+#define DCCPF_SEQ_WMIN 32
+#define DCCPF_SEQ_WMAX 0x3FFFFFFFFFFFull
+/* Maximum number of SP values that fit in a single (Confirm) option */
+#define DCCP_FEAT_MAX_SP_VALS (DCCP_SINGLE_OPT_MAXLEN - 2)
-static inline int dccp_feat_is_reserved(const u8 feat)
-{
- return (feat > DCCPF_DATA_CHECKSUM &&
- feat < DCCPF_MIN_CCID_SPECIFIC) ||
- feat == DCCPF_RESERVED;
-}
+enum dccp_feat_type {
+ FEAT_AT_RX = 1, /* located at RX side of half-connection */
+ FEAT_AT_TX = 2, /* located at TX side of half-connection */
+ FEAT_SP = 4, /* server-priority reconciliation (6.3.1) */
+ FEAT_NN = 8, /* non-negotiable reconciliation (6.3.2) */
+ FEAT_UNKNOWN = 0xFF /* not understood or invalid feature */
+};
-/* feature negotiation knows only these four option types (RFC 4340, sec. 6) */
-static inline int dccp_feat_is_valid_type(const u8 optnum)
-{
- return optnum >= DCCPO_CHANGE_L && optnum <= DCCPO_CONFIRM_R;
+enum dccp_feat_state {
+ FEAT_DEFAULT = 0, /* using default values from 6.4 */
+ FEAT_INITIALISING, /* feature is being initialised */
+ FEAT_CHANGING, /* Change sent but not confirmed yet */
+ FEAT_UNSTABLE, /* local modification in state CHANGING */
+ FEAT_STABLE /* both ends (think they) agree */
+};
-}
+/**
+ * dccp_feat_val - Container for SP or NN feature values
+ * @nn: single NN value
+ * @sp.vec: single SP value plus optional preference list
+ * @sp.len: length of @sp.vec in bytes
+ */
+typedef union {
+ u64 nn;
+ struct {
+ u8 *vec;
+ u8 len;
+ } sp;
+} dccp_feat_val;
+
+/**
+ * struct feat_entry - Data structure to perform feature negotiation
+ * @val: feature's current value (SP features may have preference list)
+ * @state: feature's current state
+ * @feat_num: one of %dccp_feature_numbers
+ * @needs_mandatory: whether Mandatory options should be sent
+ * @needs_confirm: whether to send a Confirm instead of a Change
+ * @empty_confirm: whether to send an empty Confirm (depends on @needs_confirm)
+ * @is_local: feature location (1) or feature-remote (0)
+ * @node: list pointers, entries arranged in FIFO order
+ */
+struct dccp_feat_entry {
+ dccp_feat_val val;
+ enum dccp_feat_state state:8;
+ u8 feat_num;
-#ifdef CONFIG_IP_DCCP_DEBUG
-extern const char *dccp_feat_typename(const u8 type);
-extern const char *dccp_feat_name(const u8 feat);
+ bool needs_mandatory,
+ needs_confirm,
+ empty_confirm,
+ is_local;
-static inline void dccp_feat_debug(const u8 type, const u8 feat, const u8 val)
+ struct list_head node;
+};
+
+static inline u8 dccp_feat_genopt(struct dccp_feat_entry *entry)
{
- dccp_pr_debug("%s(%s (%d), %d)\n", dccp_feat_typename(type),
- dccp_feat_name(feat), feat, val);
+ if (entry->needs_confirm)
+ return entry->is_local ? DCCPO_CONFIRM_L : DCCPO_CONFIRM_R;
+ return entry->is_local ? DCCPO_CHANGE_L : DCCPO_CHANGE_R;
}
-#else
-#define dccp_feat_debug(type, feat, val)
-#endif /* CONFIG_IP_DCCP_DEBUG */
-extern int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
- u8 *val, u8 len, gfp_t gfp);
-extern int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature,
- u8 *val, u8 len);
-extern int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
- u8 *val, u8 len);
-extern void dccp_feat_clean(struct dccp_minisock *dmsk);
-extern int dccp_feat_clone(struct sock *oldsk, struct sock *newsk);
-extern int dccp_feat_init(struct dccp_minisock *dmsk);
+/**
+ * struct ccid_dependency - Track changes resulting from choosing a CCID
+ * @dependent_feat: one of %dccp_feature_numbers
+ * @is_local: local (1) or remote (0) @dependent_feat
+ * @is_mandatory: whether presence of @dependent_feat is mission-critical or not
+ * @val: corresponding default value for @dependent_feat (u8 is sufficient here)
+ */
+struct ccid_dependency {
+ u8 dependent_feat;
+ bool is_local:1,
+ is_mandatory:1;
+ u8 val;
+};
+
+/*
+ * Sysctls to seed defaults for feature negotiation
+ */
+extern unsigned long sysctl_dccp_sequence_window;
+extern int sysctl_dccp_rx_ccid;
+extern int sysctl_dccp_tx_ccid;
+
+extern int dccp_feat_init(struct sock *sk);
+extern void dccp_feat_initialise_sysctls(void);
+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 *);
+
+/*
+ * Encoding variable-length options and their maximum length.
+ *
+ * This affects NN options (SP options are all u8) and other variable-length
+ * options (see table 3 in RFC 4340). The limit is currently given the Sequence
+ * Window NN value (sec. 7.5.2) and the NDP count (sec. 7.7) option, all other
+ * options consume less than 6 bytes (timestamps are 4 bytes).
+ * When updating this constant (e.g. due to new internet drafts / RFCs), make
+ * sure that you also update all code which refers to it.
+ */
+#define DCCP_OPTVAL_MAXLEN 6
+
+extern void dccp_encode_value_var(const u64 value, u8 *to, const u8 len);
+extern u64 dccp_decode_value_var(const u8 *bf, const u8 len);
+extern int dccp_insert_option_mandatory(struct sk_buff *skb);
+extern int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
+ u8 *val, u8 len, bool repeat_first);
#endif /* _DCCP_FEAT_H */
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff