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dccp: List management for new feature negotiation

This adds list initial fields and list management functions for the
new feature negotiation implementation.

Thanks to Arnaldo for suggestions and improvements.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: David S. Miller <davem@davemloft.net>
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1 parent 7d43d1a commit 61e6473efbd6087e1db3aaa93a5266c5bfd8aa99 @grrtrr grrtrr committed with davem330 Nov 4, 2008
Showing with 75 additions and 0 deletions.
  1. +2 −0 net/dccp/dccp.h
  2. +73 −0 net/dccp/feat.c
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2 net/dccp/dccp.h
@@ -441,6 +441,8 @@ static inline int dccp_ack_pending(const struct sock *sk)
inet_csk_ack_scheduled(sk);
}
+extern void dccp_feat_list_purge(struct list_head *fn_list);
+
extern int dccp_insert_options(struct sock *sk, struct sk_buff *skb);
extern int dccp_insert_options_rsk(struct dccp_request_sock*, struct sk_buff*);
extern int dccp_insert_option_elapsed_time(struct sock *sk,
View
73 net/dccp/feat.c
@@ -60,6 +60,79 @@ static const struct {
};
#define DCCP_FEAT_SUPPORTED_MAX ARRAY_SIZE(dccp_feat_table)
+/**
+ * dccp_feat_index - Hash function to map feature number into array position
+ * Returns consecutive array index or -1 if the feature is not understood.
+ */
+static int dccp_feat_index(u8 feat_num)
+{
+ /* The first 9 entries are occupied by the types from RFC 4340, 6.4 */
+ if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM)
+ return feat_num - 1;
+
+ /*
+ * Other features: add cases for new feature types here after adding
+ * them to the above table.
+ */
+ switch (feat_num) {
+ case DCCPF_SEND_LEV_RATE:
+ return DCCP_FEAT_SUPPORTED_MAX - 1;
+ }
+ return -1;
+}
+
+static u8 dccp_feat_type(u8 feat_num)
+{
+ int idx = dccp_feat_index(feat_num);
+
+ if (idx < 0)
+ return FEAT_UNKNOWN;
+ return dccp_feat_table[idx].reconciliation;
+}
+
+static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
+{
+ if (unlikely(val == NULL))
+ return;
+ if (dccp_feat_type(feat_num) == FEAT_SP)
+ kfree(val->sp.vec);
+ memset(val, 0, sizeof(*val));
+}
+
+static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
+{
+ if (entry != NULL) {
+ dccp_feat_val_destructor(entry->feat_num, &entry->val);
+ kfree(entry);
+ }
+}
+
+/*
+ * List management functions
+ *
+ * Feature negotiation lists rely on and maintain the following invariants:
+ * - each feat_num in the list is known, i.e. we know its type and default value
+ * - each feat_num/is_local combination is unique (old entries are overwritten)
+ * - SP values are always freshly allocated
+ * - list is sorted in increasing order of feature number (faster lookup)
+ */
+
+static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry)
+{
+ list_del(&entry->node);
+ dccp_feat_entry_destructor(entry);
+}
+
+void dccp_feat_list_purge(struct list_head *fn_list)
+{
+ struct dccp_feat_entry *entry, *next;
+
+ list_for_each_entry_safe(entry, next, fn_list, node)
+ dccp_feat_entry_destructor(entry);
+ INIT_LIST_HEAD(fn_list);
+}
+EXPORT_SYMBOL_GPL(dccp_feat_list_purge);
+
int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
u8 *val, u8 len, gfp_t gfp)
{

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