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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2008-11-05 02:38:20 -0500
committerDavid S. Miller <davem@davemloft.net>2008-11-05 02:38:20 -0500
commitbd012f2e7be9f69a47d240ded0fa491967d9827c (patch)
tree940cc895a7da7a065847cf604cddfab097e385cc
parentd5f642384e9da75393160350f75bbb9a527f7c58 (diff)
dccp: Basic data structure for feature negotiation
This patch prepares for the new and extended feature-negotiation routines. The following feature-negotiation data structures are provided: * a container for the various (SP or NN) values, * symbolic state names to track feature states, * an entry struct which holds all current information together, * elementary functions to fill in and process these structures. Entry structs are arranged as FIFO for the following reason: RFC 4340 specifies that if multiple options of the same type are present, they are processed in the order of their appearance in the packet; which means that this order needs to be preserved in the local data structure (the later insertion code also respects this order). The struct list_head has been chosen for the following reasons: the most frequent operations are * add new entry at tail (when receiving Change or setting socket options); * delete entry (when Confirm has been received); * deep copy of entire list (cloning from listening socket onto request socket). The NN value has been set to 64 bit, which is a currently sufficient upper limit (Sequence Window feature has 48 bit). Thanks to Arnaldo, who contributed the streamlined layout of the entry struct. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/dccp/feat.h61
1 files changed, 61 insertions, 0 deletions
diff --git a/net/dccp/feat.h b/net/dccp/feat.h
index e272222c7ace..56df82ceef09 100644
--- a/net/dccp/feat.h
+++ b/net/dccp/feat.h
@@ -14,6 +14,67 @@
14#include <linux/types.h> 14#include <linux/types.h>
15#include "dccp.h" 15#include "dccp.h"
16 16
17enum dccp_feat_type {
18 FEAT_AT_RX = 1, /* located at RX side of half-connection */
19 FEAT_AT_TX = 2, /* located at TX side of half-connection */
20 FEAT_SP = 4, /* server-priority reconciliation (6.3.1) */
21 FEAT_NN = 8, /* non-negotiable reconciliation (6.3.2) */
22 FEAT_UNKNOWN = 0xFF /* not understood or invalid feature */
23};
24
25enum dccp_feat_state {
26 FEAT_DEFAULT = 0, /* using default values from 6.4 */
27 FEAT_INITIALISING, /* feature is being initialised */
28 FEAT_CHANGING, /* Change sent but not confirmed yet */
29 FEAT_UNSTABLE, /* local modification in state CHANGING */
30 FEAT_STABLE /* both ends (think they) agree */
31};
32
33/**
34 * dccp_feat_val - Container for SP or NN feature values
35 * @nn: single NN value
36 * @sp.vec: single SP value plus optional preference list
37 * @sp.len: length of @sp.vec in bytes
38 */
39typedef union {
40 u64 nn;
41 struct {
42 u8 *vec;
43 u8 len;
44 } sp;
45} dccp_feat_val;
46
47/**
48 * struct feat_entry - Data structure to perform feature negotiation
49 * @val: feature's current value (SP features may have preference list)
50 * @state: feature's current state
51 * @feat_num: one of %dccp_feature_numbers
52 * @needs_mandatory: whether Mandatory options should be sent
53 * @needs_confirm: whether to send a Confirm instead of a Change
54 * @empty_confirm: whether to send an empty Confirm (depends on @needs_confirm)
55 * @is_local: feature location (1) or feature-remote (0)
56 * @node: list pointers, entries arranged in FIFO order
57 */
58struct dccp_feat_entry {
59 dccp_feat_val val;
60 enum dccp_feat_state state:8;
61 u8 feat_num;
62
63 bool needs_mandatory,
64 needs_confirm,
65 empty_confirm,
66 is_local;
67
68 struct list_head node;
69};
70
71static inline u8 dccp_feat_genopt(struct dccp_feat_entry *entry)
72{
73 if (entry->needs_confirm)
74 return entry->is_local ? DCCPO_CONFIRM_L : DCCPO_CONFIRM_R;
75 return entry->is_local ? DCCPO_CHANGE_L : DCCPO_CHANGE_R;
76}
77
17#ifdef CONFIG_IP_DCCP_DEBUG 78#ifdef CONFIG_IP_DCCP_DEBUG
18extern const char *dccp_feat_typename(const u8 type); 79extern const char *dccp_feat_typename(const u8 type);
19extern const char *dccp_feat_name(const u8 feat); 80extern const char *dccp_feat_name(const u8 feat);