dccp: Initialisation framework for feature negotiation

[mv-sheeva.git] / net / dccp / feat.h

diff --git a/net/dccp/feat.h b/net/dccp/feat.h
index 9eefdb43783efa9914a8bd7ff2d91edffd7a08ee..5e7b8481cd0466493edf6a984af4156c900b0da9 100644 (file)
--- a/net/dccp/feat.h
+++ b/net/dccp/feat.h
@@ -3,14 +3,14 @@
 /*
  *  net/dccp/feat.h
  *
- *  An implementation of the DCCP protocol
+ *  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.
+ *  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"
 
@@ -22,6 +22,8 @@
 /* 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  */
@@ -55,9 +57,9 @@ typedef union {
 
 /**
  * struct feat_entry  -  Data structure to perform feature negotiation
- * @feat_num: one of %dccp_feature_numbers
  * @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)
@@ -65,13 +67,14 @@ typedef union {
  * @node: list pointers, entries arranged in FIFO order
  */
 struct dccp_feat_entry {
-       u8                      feat_num;
        dccp_feat_val           val;
        enum dccp_feat_state    state:8;
-       bool                    needs_mandatory:1,
-                               needs_confirm:1,
-                               empty_confirm:1,
-                               is_local:1;
+       u8                      feat_num;
+
+       bool                    needs_mandatory,
+                               needs_confirm,
+                               empty_confirm,
+                               is_local;
 
        struct list_head        node;
 };
@@ -110,15 +113,30 @@ static inline void dccp_feat_debug(const u8 type, const u8 feat, const u8 val)
 #define dccp_feat_debug(type, feat, val)
 #endif /* CONFIG_IP_DCCP_DEBUG */
 
-extern int  dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
-                            u8 *val, u8 len, gfp_t gfp);
-extern int  dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature,
-                                 u8 *val, u8 len);
-extern int  dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
-                                  u8 *val, u8 len);
-extern void dccp_feat_clean(struct dccp_minisock *dmsk);
-extern int  dccp_feat_clone(struct sock *oldsk, struct sock *newsk);
-extern int  dccp_feat_clone_list(struct list_head const *, struct list_head *);
 extern int  dccp_feat_init(struct sock *sk);
+extern int  dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
+                                 u8 const *list, u8 len);
+extern int  dccp_feat_register_nn(struct sock *sk, u8 feat, u64 val);
+extern int  dccp_feat_parse_options(struct sock *, struct dccp_request_sock *,
+                                   u8 mand, u8 opt, u8 feat, u8 *val, u8 len);
+extern 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
+
+extern void dccp_encode_value_var(const u64 value, u8 *to, const u8 len);
+extern u64  dccp_decode_value_var(const u8 *bf, const u8 len);
 
+extern int  dccp_insert_option_mandatory(struct sk_buff *skb);
+extern int  dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
+                              u8 *val, u8 len, bool repeat_first);
 #endif /* _DCCP_FEAT_H */