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

/* SPDX-License-Identifier: GPL-2.0-only */
#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]>
 */
#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);
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
d2912cb1	1	/* SPDX-License-Identifier: GPL-2.0-only */
afe00251 AB	2	#ifndef _DCCP_FEAT_H
	3	#define _DCCP_FEAT_H
	4	/*
	5	* net/dccp/feat.h
	6	*
63b8e286 GR	7	* Feature negotiation for the DCCP protocol (RFC 4340, section 6)
63b8e286 GR	8	* Copyright (c) 2008 Gerrit Renker <[email protected]>
afe00251	9	* Copyright (c) 2005 Andrea Bittau <[email protected]>
afe00251	10	*/
afe00251	11	#include <linux/types.h>
c02fdc0e	12	#include "dccp.h"
afe00251	13
e8ef967a GR	14	/*
	15	* Known limit values
	16	*/
	17	/* Ack Ratio takes 2-byte integer values (11.3) */
	18	#define DCCPF_ACK_RATIO_MAX 0xFFFF
	19	/* Wmin=32 and Wmax=2^46-1 from 7.5.2 */
	20	#define DCCPF_SEQ_WMIN 32
	21	#define DCCPF_SEQ_WMAX 0x3FFFFFFFFFFFull
b20a9c24 GR	22	/* Maximum number of SP values that fit in a single (Confirm) option */
b20a9c24 GR	23	#define DCCP_FEAT_MAX_SP_VALS (DCCP_SINGLE_OPT_MAXLEN - 2)
e8ef967a	24
bd012f2e GR	25	enum dccp_feat_type {
	26	FEAT_AT_RX = 1, /* located at RX side of half-connection */
	27	FEAT_AT_TX = 2, /* located at TX side of half-connection */
	28	FEAT_SP = 4, /* server-priority reconciliation (6.3.1) */
	29	FEAT_NN = 8, /* non-negotiable reconciliation (6.3.2) */
	30	FEAT_UNKNOWN = 0xFF /* not understood or invalid feature */
	31	};
	32
	33	enum dccp_feat_state {
	34	FEAT_DEFAULT = 0, /* using default values from 6.4 */
	35	FEAT_INITIALISING, /* feature is being initialised */
	36	FEAT_CHANGING, /* Change sent but not confirmed yet */
	37	FEAT_UNSTABLE, /* local modification in state CHANGING */
	38	FEAT_STABLE /* both ends (think they) agree */
	39	};
	40
	41	/**
	42	* dccp_feat_val - Container for SP or NN feature values
	43	* @nn: single NN value
	44	* @sp.vec: single SP value plus optional preference list
	45	* @sp.len: length of @sp.vec in bytes
	46	*/
	47	typedef union {
	48	u64 nn;
	49	struct {
	50	u8 *vec;
	51	u8 len;
	52	} sp;
	53	} dccp_feat_val;
	54
	55	/**
	56	* struct feat_entry - Data structure to perform feature negotiation
	57	* @val: feature's current value (SP features may have preference list)
	58	* @state: feature's current state
	59	* @feat_num: one of %dccp_feature_numbers
	60	* @needs_mandatory: whether Mandatory options should be sent
	61	* @needs_confirm: whether to send a Confirm instead of a Change
	62	* @empty_confirm: whether to send an empty Confirm (depends on @needs_confirm)
	63	* @is_local: feature location (1) or feature-remote (0)
	64	* @node: list pointers, entries arranged in FIFO order
	65	*/
	66	struct dccp_feat_entry {
	67	dccp_feat_val val;
	68	enum dccp_feat_state state:8;
	69	u8 feat_num;
	70
	71	bool needs_mandatory,
	72	needs_confirm,
	73	empty_confirm,
	74	is_local;
	75
	76	struct list_head node;
	77	};
	78
	79	static inline u8 dccp_feat_genopt(struct dccp_feat_entry *entry)
	80	{
	81	if (entry->needs_confirm)
	82	return entry->is_local ? DCCPO_CONFIRM_L : DCCPO_CONFIRM_R;
	83	return entry->is_local ? DCCPO_CHANGE_L : DCCPO_CHANGE_R;
	84	}
	85
e8ef967a GR	86	/**
	87	* struct ccid_dependency - Track changes resulting from choosing a CCID
	88	* @dependent_feat: one of %dccp_feature_numbers
	89	* @is_local: local (1) or remote (0) @dependent_feat
	90	* @is_mandatory: whether presence of @dependent_feat is mission-critical or not
	91	* @val: corresponding default value for @dependent_feat (u8 is sufficient here)
	92	*/
	93	struct ccid_dependency {
	94	u8 dependent_feat;
	95	bool is_local:1,
	96	is_mandatory:1;
	97	u8 val;
	98	};
	99
883ca833 GR	100	/*
	101	* Sysctls to seed defaults for feature negotiation
	102	*/
	103	extern unsigned long sysctl_dccp_sequence_window;
	104	extern int sysctl_dccp_rx_ccid;
	105	extern int sysctl_dccp_tx_ccid;
	106
a402a5aa	107	int dccp_feat_init(struct sock *sk);
a402a5aa JP	108	int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
	109	u8 const *list, u8 len);
	110	int dccp_feat_parse_options(struct sock , struct dccp_request_sock ,
	111	u8 mand, u8 opt, u8 feat, u8 *val, u8 len);
	112	int dccp_feat_clone_list(struct list_head const , struct list_head );
afe00251	113
02fa460e GR	114	/*
	115	* Encoding variable-length options and their maximum length.
	116	*
	117	* This affects NN options (SP options are all u8) and other variable-length
	118	* options (see table 3 in RFC 4340). The limit is currently given the Sequence
	119	* Window NN value (sec. 7.5.2) and the NDP count (sec. 7.7) option, all other
	120	* options consume less than 6 bytes (timestamps are 4 bytes).
	121	* When updating this constant (e.g. due to new internet drafts / RFCs), make
	122	* sure that you also update all code which refers to it.
	123	*/
	124	#define DCCP_OPTVAL_MAXLEN 6
	125
a402a5aa JP	126	void dccp_encode_value_var(const u64 value, u8 *to, const u8 len);
	127	u64 dccp_decode_value_var(const u8 *bf, const u8 len);
	128	u64 dccp_feat_nn_get(struct sock *sk, u8 feat);
d3710566	129
a402a5aa JP	130	int dccp_insert_option_mandatory(struct sk_buff *skb);
	131	int dccp_insert_fn_opt(struct sk_buff skb, u8 type, u8 feat, u8 val, u8 len,
	132	bool repeat_first);
afe00251	133	#endif /* _DCCP_FEAT_H */