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 <gerrit@erg.abdn.ac.uk> Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
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@ -176,19 +176,20 @@ enum {
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};
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/* DCCP features (RFC 4340 section 6.4) */
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enum {
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enum dccp_feature_numbers {
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DCCPF_RESERVED = 0,
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DCCPF_CCID = 1,
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DCCPF_SHORT_SEQNOS = 2, /* XXX: not yet implemented */
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DCCPF_SHORT_SEQNOS = 2,
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DCCPF_SEQUENCE_WINDOW = 3,
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DCCPF_ECN_INCAPABLE = 4, /* XXX: not yet implemented */
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DCCPF_ECN_INCAPABLE = 4,
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DCCPF_ACK_RATIO = 5,
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DCCPF_SEND_ACK_VECTOR = 6,
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DCCPF_SEND_NDP_COUNT = 7,
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DCCPF_MIN_CSUM_COVER = 8,
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DCCPF_DATA_CHECKSUM = 9, /* XXX: not yet implemented */
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DCCPF_DATA_CHECKSUM = 9,
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/* 10-127 reserved */
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DCCPF_MIN_CCID_SPECIFIC = 128,
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DCCPF_SEND_LEV_RATE = 192, /* RFC 4342, sec. 8.4 */
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DCCPF_MAX_CCID_SPECIFIC = 255,
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};
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115
net/dccp/feat.c
115
net/dccp/feat.c
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@ -23,6 +23,80 @@
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#define DCCP_FEAT_SP_NOAGREE (-123)
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static const struct {
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u8 feat_num; /* DCCPF_xxx */
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enum dccp_feat_type rxtx; /* RX or TX */
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enum dccp_feat_type reconciliation; /* SP or NN */
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u8 default_value; /* as in 6.4 */
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/*
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* Lookup table for location and type of features (from RFC 4340/4342)
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* +--------------------------+----+-----+----+----+---------+-----------+
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* | Feature | Location | Reconc. | Initial | Section |
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* | | RX | TX | SP | NN | Value | Reference |
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* +--------------------------+----+-----+----+----+---------+-----------+
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* | DCCPF_CCID | | X | X | | 2 | 10 |
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* | DCCPF_SHORT_SEQNOS | | X | X | | 0 | 7.6.1 |
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* | DCCPF_SEQUENCE_WINDOW | | X | | X | 100 | 7.5.2 |
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* | DCCPF_ECN_INCAPABLE | X | | X | | 0 | 12.1 |
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* | DCCPF_ACK_RATIO | | X | | X | 2 | 11.3 |
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* | DCCPF_SEND_ACK_VECTOR | X | | X | | 0 | 11.5 |
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* | DCCPF_SEND_NDP_COUNT | | X | X | | 0 | 7.7.2 |
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* | DCCPF_MIN_CSUM_COVER | X | | X | | 0 | 9.2.1 |
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* | DCCPF_DATA_CHECKSUM | X | | X | | 0 | 9.3.1 |
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* | DCCPF_SEND_LEV_RATE | X | | X | | 0 | 4342/8.4 |
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* +--------------------------+----+-----+----+----+---------+-----------+
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*/
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} dccp_feat_table[] = {
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{ DCCPF_CCID, FEAT_AT_TX, FEAT_SP, 2 },
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{ DCCPF_SHORT_SEQNOS, FEAT_AT_TX, FEAT_SP, 0 },
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{ DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100 },
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{ DCCPF_ECN_INCAPABLE, FEAT_AT_RX, FEAT_SP, 0 },
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{ DCCPF_ACK_RATIO, FEAT_AT_TX, FEAT_NN, 2 },
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{ DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0 },
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{ DCCPF_SEND_NDP_COUNT, FEAT_AT_TX, FEAT_SP, 0 },
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{ DCCPF_MIN_CSUM_COVER, FEAT_AT_RX, FEAT_SP, 0 },
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{ DCCPF_DATA_CHECKSUM, FEAT_AT_RX, FEAT_SP, 0 },
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{ DCCPF_SEND_LEV_RATE, FEAT_AT_RX, FEAT_SP, 0 },
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};
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#define DCCP_FEAT_SUPPORTED_MAX ARRAY_SIZE(dccp_feat_table)
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/**
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* dccp_feat_index - Hash function to map feature number into array position
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* Returns consecutive array index or -1 if the feature is not understood.
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*/
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static int dccp_feat_index(u8 feat_num)
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{
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/* The first 9 entries are occupied by the types from RFC 4340, 6.4 */
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if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM)
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return feat_num - 1;
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/*
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* Other features: add cases for new feature types here after adding
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* them to the above table.
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*/
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switch (feat_num) {
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case DCCPF_SEND_LEV_RATE:
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return DCCP_FEAT_SUPPORTED_MAX - 1;
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}
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return -1;
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}
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static u8 dccp_feat_type(u8 feat_num)
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{
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int idx = dccp_feat_index(feat_num);
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if (idx < 0)
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return FEAT_UNKNOWN;
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return dccp_feat_table[idx].reconciliation;
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}
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static int dccp_feat_default_value(u8 feat_num)
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{
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int idx = dccp_feat_index(feat_num);
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return idx < 0 ? : dccp_feat_table[idx].default_value;
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}
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/* copy constructor, fval must not already contain allocated memory */
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static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
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{
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@ -37,6 +111,45 @@ static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
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return 0;
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}
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static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
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{
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if (unlikely(val == NULL))
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return;
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if (dccp_feat_type(feat_num) == FEAT_SP)
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kfree(val->sp.vec);
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memset(val, 0, sizeof(*val));
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}
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static struct dccp_feat_entry *
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dccp_feat_clone_entry(struct dccp_feat_entry const *original)
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{
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struct dccp_feat_entry *new;
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u8 type = dccp_feat_type(original->feat_num);
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if (type == FEAT_UNKNOWN)
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return NULL;
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new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
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if (new == NULL)
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return NULL;
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if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
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original->val.sp.vec,
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original->val.sp.len)) {
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kfree(new);
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return NULL;
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}
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return new;
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}
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static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
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{
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if (entry != NULL) {
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dccp_feat_val_destructor(entry->feat_num, &entry->val);
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kfree(entry);
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}
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}
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int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
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u8 *val, u8 len, gfp_t gfp)
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{
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@ -653,6 +766,8 @@ const char *dccp_feat_name(const u8 feat)
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if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
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return feature_names[DCCPF_RESERVED];
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if (feat == DCCPF_SEND_LEV_RATE)
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return "Send Loss Event Rate";
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if (feat >= DCCPF_MIN_CCID_SPECIFIC)
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return "CCID-specific";
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