[linux.git] / net / dccp / feat.h

#ifndef _DCCP_FEAT_H
#define _DCCP_FEAT_H
/*
 *  net/dccp/feat.h
 *
 *  Feature negotiation for the DCCP protocol (RFC 4340, section 6)
 *  Copyright (c) 2008 Gerrit Renker <[email protected]>
 *  Copyright (c) 2005 Andrea Bittau <[email protected]>
 *
 *  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"

/*
 * 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)

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	  */
};

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;

	bool			needs_mandatory,
				needs_confirm,
				empty_confirm,
				is_local;

	struct list_head	node;
};

static inline u8 dccp_feat_genopt(struct dccp_feat_entry *entry)
{
	if (entry->needs_confirm)
		return entry->is_local ? DCCPO_CONFIRM_L : DCCPO_CONFIRM_R;
	return entry->is_local ? DCCPO_CHANGE_L : DCCPO_CHANGE_R;
}

/**
 * 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;

int dccp_feat_init(struct sock *sk);
void dccp_feat_initialise_sysctls(void);
int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
			  u8 const *list, u8 len);
int dccp_feat_parse_options(struct sock *, struct dccp_request_sock *,
			    u8 mand, u8 opt, u8 feat, u8 *val, u8 len);
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

void dccp_encode_value_var(const u64 value, u8 *to, const u8 len);
u64 dccp_decode_value_var(const u8 *bf, const u8 len);
u64 dccp_feat_nn_get(struct sock *sk, u8 feat);

int dccp_insert_option_mandatory(struct sk_buff *skb);
int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat, u8 *val, u8 len,
		       bool repeat_first);
#endif /* _DCCP_FEAT_H */
Commit	Line	Data
afe00251 AB	1	#ifndef _DCCP_FEAT_H
	2	#define _DCCP_FEAT_H
	3	/*
	4	* net/dccp/feat.h
	5	*
63b8e286 GR	6	* Feature negotiation for the DCCP protocol (RFC 4340, section 6)
63b8e286 GR	7	* Copyright (c) 2008 Gerrit Renker <[email protected]>
afe00251 AB	8	* Copyright (c) 2005 Andrea Bittau <[email protected]>
afe00251 AB	9	*
63b8e286 GR	10	* This program is free software; you can redistribute it and/or modify it
	11	* under the terms of the GNU General Public License version 2 as
	12	* published by the Free Software Foundation.
afe00251	13	*/
afe00251	14	#include <linux/types.h>
c02fdc0e	15	#include "dccp.h"
afe00251	16
e8ef967a GR	17	/*
	18	* Known limit values
	19	*/
	20	/* Ack Ratio takes 2-byte integer values (11.3) */
	21	#define DCCPF_ACK_RATIO_MAX 0xFFFF
	22	/* Wmin=32 and Wmax=2^46-1 from 7.5.2 */
	23	#define DCCPF_SEQ_WMIN 32
	24	#define DCCPF_SEQ_WMAX 0x3FFFFFFFFFFFull
b20a9c24 GR	25	/* Maximum number of SP values that fit in a single (Confirm) option */
b20a9c24 GR	26	#define DCCP_FEAT_MAX_SP_VALS (DCCP_SINGLE_OPT_MAXLEN - 2)
e8ef967a	27
bd012f2e GR	28	enum dccp_feat_type {
	29	FEAT_AT_RX = 1, /* located at RX side of half-connection */
	30	FEAT_AT_TX = 2, /* located at TX side of half-connection */
	31	FEAT_SP = 4, /* server-priority reconciliation (6.3.1) */
	32	FEAT_NN = 8, /* non-negotiable reconciliation (6.3.2) */
	33	FEAT_UNKNOWN = 0xFF /* not understood or invalid feature */
	34	};
	35
	36	enum dccp_feat_state {
	37	FEAT_DEFAULT = 0, /* using default values from 6.4 */
	38	FEAT_INITIALISING, /* feature is being initialised */
	39	FEAT_CHANGING, /* Change sent but not confirmed yet */
	40	FEAT_UNSTABLE, /* local modification in state CHANGING */
	41	FEAT_STABLE /* both ends (think they) agree */
	42	};
	43
	44	/**
	45	* dccp_feat_val - Container for SP or NN feature values
	46	* @nn: single NN value
	47	* @sp.vec: single SP value plus optional preference list
	48	* @sp.len: length of @sp.vec in bytes
	49	*/
	50	typedef union {
	51	u64 nn;
	52	struct {
	53	u8 *vec;
	54	u8 len;
	55	} sp;
	56	} dccp_feat_val;
	57
	58	/**
	59	* struct feat_entry - Data structure to perform feature negotiation
	60	* @val: feature's current value (SP features may have preference list)
	61	* @state: feature's current state
	62	* @feat_num: one of %dccp_feature_numbers
	63	* @needs_mandatory: whether Mandatory options should be sent
	64	* @needs_confirm: whether to send a Confirm instead of a Change
	65	* @empty_confirm: whether to send an empty Confirm (depends on @needs_confirm)
	66	* @is_local: feature location (1) or feature-remote (0)
	67	* @node: list pointers, entries arranged in FIFO order
	68	*/
	69	struct dccp_feat_entry {
	70	dccp_feat_val val;
	71	enum dccp_feat_state state:8;
	72	u8 feat_num;
	73
	74	bool needs_mandatory,
	75	needs_confirm,
	76	empty_confirm,
	77	is_local;
	78
	79	struct list_head node;
	80	};
	81
	82	static inline u8 dccp_feat_genopt(struct dccp_feat_entry *entry)
	83	{
	84	if (entry->needs_confirm)
	85	return entry->is_local ? DCCPO_CONFIRM_L : DCCPO_CONFIRM_R;
	86	return entry->is_local ? DCCPO_CHANGE_L : DCCPO_CHANGE_R;
	87	}
	88
e8ef967a GR	89	/**
	90	* struct ccid_dependency - Track changes resulting from choosing a CCID
	91	* @dependent_feat: one of %dccp_feature_numbers
	92	* @is_local: local (1) or remote (0) @dependent_feat
	93	* @is_mandatory: whether presence of @dependent_feat is mission-critical or not
	94	* @val: corresponding default value for @dependent_feat (u8 is sufficient here)
	95	*/
	96	struct ccid_dependency {
	97	u8 dependent_feat;
	98	bool is_local:1,
	99	is_mandatory:1;
	100	u8 val;
	101	};
	102
883ca833 GR	103	/*
	104	* Sysctls to seed defaults for feature negotiation
	105	*/
	106	extern unsigned long sysctl_dccp_sequence_window;
	107	extern int sysctl_dccp_rx_ccid;
	108	extern int sysctl_dccp_tx_ccid;
	109
a402a5aa JP	110	int dccp_feat_init(struct sock *sk);
	111	void dccp_feat_initialise_sysctls(void);
	112	int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
	113	u8 const *list, u8 len);
	114	int dccp_feat_parse_options(struct sock , struct dccp_request_sock ,
	115	u8 mand, u8 opt, u8 feat, u8 *val, u8 len);
	116	int dccp_feat_clone_list(struct list_head const , struct list_head );
afe00251	117
02fa460e GR	118	/*
	119	* Encoding variable-length options and their maximum length.
	120	*
	121	* This affects NN options (SP options are all u8) and other variable-length
	122	* options (see table 3 in RFC 4340). The limit is currently given the Sequence
	123	* Window NN value (sec. 7.5.2) and the NDP count (sec. 7.7) option, all other
	124	* options consume less than 6 bytes (timestamps are 4 bytes).
	125	* When updating this constant (e.g. due to new internet drafts / RFCs), make
	126	* sure that you also update all code which refers to it.
	127	*/
	128	#define DCCP_OPTVAL_MAXLEN 6
	129
a402a5aa JP	130	void dccp_encode_value_var(const u64 value, u8 *to, const u8 len);
	131	u64 dccp_decode_value_var(const u8 *bf, const u8 len);
	132	u64 dccp_feat_nn_get(struct sock *sk, u8 feat);
d3710566	133
a402a5aa JP	134	int dccp_insert_option_mandatory(struct sk_buff *skb);
	135	int dccp_insert_fn_opt(struct sk_buff skb, u8 type, u8 feat, u8 val, u8 len,
	136	bool repeat_first);
afe00251	137	#endif /* _DCCP_FEAT_H */