1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
2 | #ifndef _DCCP_FEAT_H |
3 | #define _DCCP_FEAT_H |
4 | /* |
5 | * net/dccp/feat.h |
6 | * |
7 | * Feature negotiation for the DCCP protocol (RFC 4340, section 6) |
8 | * Copyright (c) 2008 Gerrit Renker <gerrit@erg.abdn.ac.uk> |
9 | * Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk> |
10 | */ |
11 | #include <linux/types.h> |
12 | #include "dccp.h" |
13 | |
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 |
22 | /* Maximum number of SP values that fit in a single (Confirm) option */ |
23 | #define DCCP_FEAT_MAX_SP_VALS (DCCP_SINGLE_OPT_MAXLEN - 2) |
24 | |
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 | |
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 | |
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 | |
107 | int dccp_feat_init(struct sock *sk); |
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 *); |
113 | |
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 | |
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); |
129 | |
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); |
133 | #endif /* _DCCP_FEAT_H */ |
134 | |