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Andrea Bittauafe00252006-03-20 17:43:56 -08001#ifndef _DCCP_FEAT_H
2#define _DCCP_FEAT_H
3/*
4 * net/dccp/feat.h
5 *
Gerrit Renker63b8e282008-12-08 01:17:32 -08006 * Feature negotiation for the DCCP protocol (RFC 4340, section 6)
7 * Copyright (c) 2008 Gerrit Renker <gerrit@erg.abdn.ac.uk>
Andrea Bittauafe00252006-03-20 17:43:56 -08008 * Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
9 *
Gerrit Renker63b8e282008-12-08 01:17:32 -080010 * 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.
Andrea Bittauafe00252006-03-20 17:43:56 -080013 */
Andrea Bittauafe00252006-03-20 17:43:56 -080014#include <linux/types.h>
Gerrit Renkerc02fdc02006-11-14 12:48:10 -020015#include "dccp.h"
Andrea Bittauafe00252006-03-20 17:43:56 -080016
Gerrit Renkere8ef9672008-11-12 00:43:40 -080017/*
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
Gerrit Renkerb20a9c22008-11-23 16:02:31 -080025/* Maximum number of SP values that fit in a single (Confirm) option */
26#define DCCP_FEAT_MAX_SP_VALS (DCCP_SINGLE_OPT_MAXLEN - 2)
Gerrit Renkere8ef9672008-11-12 00:43:40 -080027
Gerrit Renkerbd012f22008-11-04 23:38:20 -080028enum 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
36enum 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 */
50typedef 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 */
69struct 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
82static 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
Gerrit Renkere8ef9672008-11-12 00:43:40 -080089/**
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 */
96struct ccid_dependency {
97 u8 dependent_feat;
98 bool is_local:1,
99 is_mandatory:1;
100 u8 val;
101};
102
Gerrit Renker883ca832009-01-16 23:36:32 +0000103/*
104 * Sysctls to seed defaults for feature negotiation
105 */
106extern unsigned long sysctl_dccp_sequence_window;
107extern int sysctl_dccp_rx_ccid;
108extern int sysctl_dccp_tx_ccid;
109
Gerrit Renkerf90f92e2009-01-16 23:36:30 +0000110extern int dccp_feat_init(struct sock *sk);
Gerrit Renker883ca832009-01-16 23:36:32 +0000111extern void dccp_feat_initialise_sysctls(void);
Gerrit Renker49aebc62008-11-16 22:51:23 -0800112extern int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
113 u8 const *list, u8 len);
114extern int dccp_feat_register_nn(struct sock *sk, u8 feat, u64 val);
Gerrit Renkere77b8362008-12-01 23:32:35 -0800115extern int dccp_feat_parse_options(struct sock *, struct dccp_request_sock *,
116 u8 mand, u8 opt, u8 feat, u8 *val, u8 len);
Gerrit Renkerac757732008-11-04 23:55:49 -0800117extern int dccp_feat_clone_list(struct list_head const *, struct list_head *);
Andrea Bittauafe00252006-03-20 17:43:56 -0800118
Gerrit Renker02fa4602008-11-23 16:07:53 -0800119/*
120 * Encoding variable-length options and their maximum length.
121 *
122 * This affects NN options (SP options are all u8) and other variable-length
123 * options (see table 3 in RFC 4340). The limit is currently given the Sequence
124 * Window NN value (sec. 7.5.2) and the NDP count (sec. 7.7) option, all other
125 * options consume less than 6 bytes (timestamps are 4 bytes).
126 * When updating this constant (e.g. due to new internet drafts / RFCs), make
127 * sure that you also update all code which refers to it.
128 */
129#define DCCP_OPTVAL_MAXLEN 6
130
131extern void dccp_encode_value_var(const u64 value, u8 *to, const u8 len);
132extern u64 dccp_decode_value_var(const u8 *bf, const u8 len);
Gerrit Renkerd3710562008-11-23 16:09:11 -0800133
134extern int dccp_insert_option_mandatory(struct sk_buff *skb);
Gerrit Renker8c862c22008-11-23 16:10:23 -0800135extern int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
136 u8 *val, u8 len, bool repeat_first);
Andrea Bittauafe00252006-03-20 17:43:56 -0800137#endif /* _DCCP_FEAT_H */