#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 <gerrit@erg.abdn.ac.uk> * Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk> * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #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); void dccp_feat_initialise_sysctls(void); 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 */