1 #ifndef _DCCP_FEAT_H 2 #define _DCCP_FEAT_H 3 /* 4 * net/dccp/feat.h 5 * 6 * Feature negotiation for the DCCP protocol (RFC 4340, section 6) 7 * Copyright (c) 2008 Gerrit Renker <gerrit@erg.abdn.ac.uk> 8 * Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk> 9 * 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. 13 */ 14 #include <linux/types.h> 15 #include "dccp.h" 16 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 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) 27 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 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 }; 102 103 /* 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; 109 110 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 *); 117 118 /* 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 6 129 130 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); 133 134 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); 137 #endif /* _DCCP_FEAT_H */ 138