net/dccp/feat.h

   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>
  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
  26 enum dccp_feat_type {
  27         FEAT_AT_RX   = 1,       /* located at RX side of half-connection  */
  28         FEAT_AT_TX   = 2,       /* located at TX side of half-connection  */
  29         FEAT_SP      = 4,       /* server-priority reconciliation (6.3.1) */
  30         FEAT_NN      = 8,       /* non-negotiable reconciliation (6.3.2)  */
  31         FEAT_UNKNOWN = 0xFF     /* not understood or invalid feature      */
  32 };
  33
  34 enum dccp_feat_state {
  35         FEAT_DEFAULT = 0,       /* using default values from 6.4 */
  36         FEAT_INITIALISING,      /* feature is being initialised  */
  37         FEAT_CHANGING,          /* Change sent but not confirmed yet */
  38         FEAT_UNSTABLE,          /* local modification in state CHANGING */
  39         FEAT_STABLE             /* both ends (think they) agree */
  40 };
  41
  42 /**
  43  * dccp_feat_val  -  Container for SP or NN feature values
  44  * @nn:     single NN value
  45  * @sp.vec: single SP value plus optional preference list
  46  * @sp.len: length of @sp.vec in bytes
  47  */
  48 typedef union {
  49         u64 nn;
  50         struct {
  51                 u8      *vec;
  52                 u8      len;
  53         }   sp;
  54 } dccp_feat_val;
  55
  56 /**
  57  * struct feat_entry  -  Data structure to perform feature negotiation
  58  * @val: feature's current value (SP features may have preference list)
  59  * @state: feature's current state
  60  * @feat_num: one of %dccp_feature_numbers
  61  * @needs_mandatory: whether Mandatory options should be sent
  62  * @needs_confirm: whether to send a Confirm instead of a Change
  63  * @empty_confirm: whether to send an empty Confirm (depends on @needs_confirm)
  64  * @is_local: feature location (1) or feature-remote (0)
  65  * @node: list pointers, entries arranged in FIFO order
  66  */
  67 struct dccp_feat_entry {
  68         dccp_feat_val           val;
  69         enum dccp_feat_state    state:8;
  70         u8                      feat_num;
  71
  72         bool                    needs_mandatory,
  73                                 needs_confirm,
  74                                 empty_confirm,
  75                                 is_local;
  76
  77         struct list_head        node;
  78 };
  79
  80 static inline u8 dccp_feat_genopt(struct dccp_feat_entry *entry)
  81 {
  82         if (entry->needs_confirm)
  83                 return entry->is_local ? DCCPO_CONFIRM_L : DCCPO_CONFIRM_R;
  84         return entry->is_local ? DCCPO_CHANGE_L : DCCPO_CHANGE_R;
  85 }
  86
  87 /**
  88  * struct ccid_dependency  -  Track changes resulting from choosing a CCID
  89  * @dependent_feat: one of %dccp_feature_numbers
  90  * @is_local: local (1) or remote (0) @dependent_feat
  91  * @is_mandatory: whether presence of @dependent_feat is mission-critical or not
  92  * @val: corresponding default value for @dependent_feat (u8 is sufficient here)
  93  */
  94 struct ccid_dependency {
  95         u8      dependent_feat;
  96         bool    is_local:1,
  97                 is_mandatory:1;
  98         u8      val;
  99 };
 100
 101 #ifdef CONFIG_IP_DCCP_DEBUG
 102 extern const char *dccp_feat_typename(const u8 type);
 103 extern const char *dccp_feat_name(const u8 feat);
 104
 105 static inline void dccp_feat_debug(const u8 type, const u8 feat, const u8 val)
 106 {
 107         dccp_pr_debug("%s(%s (%d), %d)\n", dccp_feat_typename(type),
 108                                            dccp_feat_name(feat), feat, val);
 109 }
 110 #else
 111 #define dccp_feat_debug(type, feat, val)
 112 #endif /* CONFIG_IP_DCCP_DEBUG */
 113
 114 extern int  dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
 115                                   u8 const *list, u8 len);
 116 extern int  dccp_feat_register_nn(struct sock *sk, u8 feat, u64 val);
 117 extern int  dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature,
 118                                   u8 *val, u8 len);
 119 extern int  dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
 120                                    u8 *val, u8 len);
 121 extern void dccp_feat_clean(struct dccp_minisock *dmsk);
 122 extern int  dccp_feat_clone(struct sock *oldsk, struct sock *newsk);
 123 extern int  dccp_feat_clone_list(struct list_head const *, struct list_head *);
 124 extern int  dccp_feat_init(struct sock *sk);
 125
 126 #endif /* _DCCP_FEAT_H */