[PATCH 02/37] dccp: Implement lookup table for feature-negotiation information

A lookup table for feature-negotiation information, extracted from RFC 4340/42,
is provided by this patch. All currently known features can be found in this
table, along with their feature location, their default value, and type.

Signed-off-by: Gerrit Renker
Acked-by: Ian McDonald
---
include/linux/dccp.h | 9 ++--
net/dccp/feat.c | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 117 insertions(+), 4 deletions(-)

--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -176,19 +176,20 @@ enum {
};

/* DCCP features (RFC 4340 section 6.4) */
-enum {
+enum dccp_feature_numbers {
DCCPF_RESERVED = 0,
DCCPF_CCID = 1,
- DCCPF_SHORT_SEQNOS = 2, /* XXX: not yet implemented */
+ DCCPF_SHORT_SEQNOS = 2,
DCCPF_SEQUENCE_WINDOW = 3,
- DCCPF_ECN_INCAPABLE = 4, /* XXX: not yet implemented */
+ DCCPF_ECN_INCAPABLE = 4,
DCCPF_ACK_RATIO = 5,
DCCPF_SEND_ACK_VECTOR = 6,
DCCPF_SEND_NDP_COUNT = 7,
DCCPF_MIN_CSUM_COVER = 8,
- DCCPF_DATA_CHECKSUM = 9, /* XXX: not yet implemented */
+ DCCPF_DATA_CHECKSUM = 9,
/* 10-127 reserved */
DCCPF_MIN_CCID_SPECIFIC = 128,
+ DCCPF_SEND_LEV_RATE = 192, /* RFC 4342, sec. 8.4 */
DCCPF_MAX_CCID_SPECIFIC = 255,
};

--- a/net/dccp/feat.c
+++ b/net/dccp/feat.c
@@ -23,6 +23,80 @@

#define DCCP_FEAT_SP_NOAGREE (-123)

+static const struct {
+ u8 feat_num; /* DCCPF_xxx */
+ enum dccp_feat_type rxtx; /* RX or TX */
+ enum dccp_feat_type reconciliation; /* SP or NN */
+ u8 default_value; /* as in 6.4 */
+/*
+ * Lookup table for location and type of features (from RFC 4340/4342)
+ * +--------------------------+----+-----+----+----+---------+-----------+
+ * | Feature | Location | Reconc. | Initial | Section |
+ * | | RX | TX | SP | NN | Value | Reference |
+ * +--------------------------+----+-----+----+----+---------+-----------+
+ * | DCCPF_CCID | | X | X | | 2 | 10 |
+ * | DCCPF_SHORT_SEQNOS | | X | X | | 0 | 7.6.1 |
+ * | DCCPF_SEQUENCE_WINDOW | | X | | X | 100 | 7.5.2 |
+ * | DCCPF_ECN_INCAPABLE | X | | X | | 0 | 12.1 |
+ * | DCCPF_ACK_RATIO | | X | | X | 2 | 11.3 |
+ * | DCCPF_SEND_ACK_VECTOR | X | | X | | 0 | 11.5 |
+ * | DCCPF_SEND_NDP_COUNT | | X | X | | 0 | 7.7.2 |
+ * | DCCPF_MIN_CSUM_COVER | X | | X | | 0 | 9.2.1 |
+ * | DCCPF_DATA_CHECKSUM | X | | X | | 0 | 9.3.1 |
+ * | DCCPF_SEND_LEV_RATE | X | | X | | 0 | 4342/8.4 |
+ * +--------------------------+----+-----+----+----+---------+-----------+
+ */
+} dccp_feat_table[] = {
+ { DCCPF_CCID, FEAT_AT_TX, FEAT_SP, 2 },
+ { DCCPF_SHORT_SEQNOS, FEAT_AT_TX, FEAT_SP, 0 },
+ { DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100 },
+ { DCCPF_ECN_INCAPABLE, FEAT_AT_RX, FEAT_SP, 0 },
+ { DCCPF_ACK_RATIO, FEAT_AT_TX, FEAT_NN, 2 },
+ { DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0 },
+ { DCCPF_SEND_NDP_COUNT, FEAT_AT_TX, FEAT_SP, 0 },
+ { DCCPF_MIN_CSUM_COVER, FEAT_AT_RX, FEAT_SP, 0 },
+ { DCCPF_DATA_CHECKSUM, FEAT_AT_RX, FEAT_SP, 0 },
+ { DCCPF_SEND_LEV_RATE, FEAT_AT_RX, FEAT_SP, 0 },
+};
+#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 int dccp_feat_default_value(u8 feat_num)
+{
+ int idx = dccp_feat_index(feat_num);
+
+ return idx < 0 ? : dccp_feat_table[idx].default_value;
+}
+
/* copy constructor, fval must not already contain allocated memory */
static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
{
@@ -37,6 +111,42 @@ static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
return 0;
}

+static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
+{
+ if (val && dccp_feat_type(feat_num) == FEAT_SP)
+ kfree(val->sp.vec);
+}
+
+static struct dccp_feat_entry *
+ dccp_feat_clone_entry(struct dccp_feat_entry const *original)
+{
+ struct dccp_feat_entry *new;
+ u8 type = dccp_feat_type(original->feat_num);
+
+ if (type == FEAT_UNKNOWN)
+ return NULL;
+
+ new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
+ if (new == NULL)
+ return NULL;
+
+ if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
+ original->val.sp.vec,
+ original->val.sp.len)) {
+ kfree(new);
+ return NULL;
+ }
+ return new;
+}
+
+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);
+ }
+}
+
int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
u8 *val, u8 len, gfp_t gfp)
{
@@ -653,6 +763,8 @@ const char *dccp_feat_name(const u8 feat)
if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
return feature_names[DCCPF_RESERVED];

+ if (feat == DCCPF_SEND_LEV_RATE)
+ return "Send Loss Event Rate";
if (feat >= DCCPF_MIN_CCID_SPECIFIC)
return "CCID-specific";

--
1.6.0.rc2

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[PATCH 02/37] dccp: Implement lookup table for feature-negotiation information

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