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Diffstat (limited to 'net/dccp/feat.h')
| -rw-r--r-- | net/dccp/feat.h | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/net/dccp/feat.h b/net/dccp/feat.h new file mode 100644 index 000000000..0e75cebb2 --- /dev/null +++ b/net/dccp/feat.h @@ -0,0 +1,137 @@ +#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 */ |