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dccp: Header option insertion routine for feature-negotiation
[net-next-2.6.git] / net / dccp / feat.h
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afe00251
AB		 1#ifndef _DCCP_FEAT_H
2#define _DCCP_FEAT_H
3/*
4 * net/dccp/feat.h
5 *
6 * An implementation of the DCCP protocol
7 * Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
8 *
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12 */
13
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 */
26#define DCCP_FEAT_MAX_SP_VALS (DCCP_SINGLE_OPT_MAXLEN - 2)
e8ef967a 27
bd012f2e
GR		 28enum 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
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 */
96struct ccid_dependency {
97 u8 dependent_feat;
98 bool is_local:1,
99 is_mandatory:1;
100 u8 val;
101};
102
c02fdc0e
GR		 103#ifdef CONFIG_IP_DCCP_DEBUG
104extern const char *dccp_feat_typename(const u8 type);
105extern const char *dccp_feat_name(const u8 feat);
106
107static inline void dccp_feat_debug(const u8 type, const u8 feat, const u8 val)
108{
109 dccp_pr_debug("%s(%s (%d), %d)\n", dccp_feat_typename(type),
110 dccp_feat_name(feat), feat, val);
111}
112#else
113#define dccp_feat_debug(type, feat, val)
114#endif /* CONFIG_IP_DCCP_DEBUG */
afe00251 115
49aebc66
GR		 116extern int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
117 u8 const *list, u8 len);
118extern int dccp_feat_register_nn(struct sock *sk, u8 feat, u64 val);
afe00251
AB		 119extern int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature,
120 u8 *val, u8 len);
121extern int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
122 u8 *val, u8 len);
8ca0d17b 123extern void dccp_feat_clean(struct dccp_minisock *dmsk);
afe00251 124extern int dccp_feat_clone(struct sock *oldsk, struct sock *newsk);
ac75773c 125extern int dccp_feat_clone_list(struct list_head const *, struct list_head *);
e8ef967a 126extern int dccp_feat_init(struct sock *sk);
afe00251 127
02fa460e
GR		 128/*
129 * Encoding variable-length options and their maximum length.
130 *
131 * This affects NN options (SP options are all u8) and other variable-length
132 * options (see table 3 in RFC 4340). The limit is currently given the Sequence
133 * Window NN value (sec. 7.5.2) and the NDP count (sec. 7.7) option, all other
134 * options consume less than 6 bytes (timestamps are 4 bytes).
135 * When updating this constant (e.g. due to new internet drafts / RFCs), make
136 * sure that you also update all code which refers to it.
137 */
138#define DCCP_OPTVAL_MAXLEN 6
139
140extern void dccp_encode_value_var(const u64 value, u8 *to, const u8 len);
141extern u64 dccp_decode_value_var(const u8 *bf, const u8 len);
d3710566
GR		 142
143extern int dccp_insert_option_mandatory(struct sk_buff *skb);
8c862c23
GR		 144extern int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
145 u8 *val, u8 len, bool repeat_first);
afe00251 146#endif /* _DCCP_FEAT_H */
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