dccp: Registration routines for changing feature values

Two registration routines, for SP and NN features, are provided by this patch,
replacing a previous routine which was used for both feature types.

These are internal-only routines and therefore start with `__feat_register'.

It further exports the known limits of Sequence Window and Ack Ratio as symbolic
constants.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>

1 files changed, 100 insertions, 23 deletions

diff --git a/net/dccp/feat.c b/net/dccp/feat.c
index 77ce2f6b0319..b859722fba72 100644
--- a/net/dccp/feat.c
+++ b/net/dccp/feat.c
@@ -300,6 +300,95 @@ cloning_failed:
         return -ENOMEM;
 }
 
+static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val)
+{
+        switch (feat_num) {
+        case DCCPF_ACK_RATIO:
+                return val <= DCCPF_ACK_RATIO_MAX;
+        case DCCPF_SEQUENCE_WINDOW:
+                return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX;
+        }
+        return 0;       /* feature unknown - so we can't tell */
+}
+
+/* check that SP values are within the ranges defined in RFC 4340 */
+static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val)
+{
+        switch (feat_num) {
+        case DCCPF_CCID:
+                return val == DCCPC_CCID2 || val == DCCPC_CCID3;
+        /* Type-check Boolean feature values: */
+        case DCCPF_SHORT_SEQNOS:
+        case DCCPF_ECN_INCAPABLE:
+        case DCCPF_SEND_ACK_VECTOR:
+        case DCCPF_SEND_NDP_COUNT:
+        case DCCPF_DATA_CHECKSUM:
+        case DCCPF_SEND_LEV_RATE:
+                return val < 2;
+        case DCCPF_MIN_CSUM_COVER:
+                return val < 16;
+        }
+        return 0;                       /* feature unknown */
+}
+
+static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len)
+{
+        if (sp_list == NULL || sp_len < 1)
+                return 0;
+        while (sp_len--)
+                if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++))
+                        return 0;
+        return 1;
+}
+
+/**
+ * __feat_register_nn  -  Register new NN value on socket
+ * @fn: feature-negotiation list to register with
+ * @feat: an NN feature from %dccp_feature_numbers
+ * @mandatory: use Mandatory option if 1
+ * @nn_val: value to register (restricted to 4 bytes)
+ * Note that NN features are local by definition (RFC 4340, 6.3.2).
+ */
+static int __feat_register_nn(struct list_head *fn, u8 feat,
+                              u8 mandatory, u64 nn_val)
+{
+        dccp_feat_val fval = { .nn = nn_val };
+
+        if (dccp_feat_type(feat) != FEAT_NN ||
+            !dccp_feat_is_valid_nn_val(feat, nn_val))
+                return -EINVAL;
+
+        /* Don't bother with default values, they will be activated anyway. */
+        if (nn_val - (u64)dccp_feat_default_value(feat) == 0)
+                return 0;
+
+        return dccp_feat_push_change(fn, feat, 1, mandatory, &fval);
+}
+
+/**
+ * __feat_register_sp  -  Register new SP value/list on socket
+ * @fn: feature-negotiation list to register with
+ * @feat: an SP feature from %dccp_feature_numbers
+ * @is_local: whether the local (1) or the remote (0) @feat is meant
+ * @mandatory: use Mandatory option if 1
+ * @sp_val: SP value followed by optional preference list
+ * @sp_len: length of @sp_val in bytes
+ */
+static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local,
+                              u8 mandatory, u8 const *sp_val, u8 sp_len)
+{
+        dccp_feat_val fval;
+
+        if (dccp_feat_type(feat) != FEAT_SP ||
+            !dccp_feat_sp_list_ok(feat, sp_val, sp_len))
+                return -EINVAL;
+
+        if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len))
+                return -ENOMEM;
+
+        return dccp_feat_push_change(fn, feat, is_local, mandatory, &fval);
+}
+
 int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
                      u8 *val, u8 len, gfp_t gfp)
 {
@@ -836,42 +925,30 @@ out_clean:
 
 EXPORT_SYMBOL_GPL(dccp_feat_clone);
 
-static int __dccp_feat_init(struct dccp_minisock *dmsk, u8 type, u8 feat,
-                            u8 *val, u8 len)
-{
-        int rc = -ENOMEM;
-        u8 *copy = kmemdup(val, len, GFP_KERNEL);
-
-        if (copy != NULL) {
-                rc = dccp_feat_change(dmsk, type, feat, copy, len, GFP_KERNEL);
-                if (rc)
-                        kfree(copy);
-        }
-        return rc;
-}
-
-int dccp_feat_init(struct dccp_minisock *dmsk)
+int dccp_feat_init(struct sock *sk)
 {
+        struct dccp_sock *dp = dccp_sk(sk);
+        struct dccp_minisock *dmsk = dccp_msk(sk);
         int rc;
 
-        INIT_LIST_HEAD(&dmsk->dccpms_pending);
-        INIT_LIST_HEAD(&dmsk->dccpms_conf);
+        INIT_LIST_HEAD(&dmsk->dccpms_pending);  /* XXX no longer used */
+        INIT_LIST_HEAD(&dmsk->dccpms_conf);     /* XXX no longer used */
 
         /* CCID L */
-        rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_CCID,
-                              &dmsk->dccpms_tx_ccid, 1);
+        rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 1, 0,
+                                &dmsk->dccpms_tx_ccid, 1);
         if (rc)
                 goto out;
 
         /* CCID R */
-        rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_R, DCCPF_CCID,
-                              &dmsk->dccpms_rx_ccid, 1);
+        rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 0, 0,
+                                &dmsk->dccpms_rx_ccid, 1);
         if (rc)
                 goto out;
 
         /* Ack ratio */
-        rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_ACK_RATIO,
-                              &dmsk->dccpms_ack_ratio, 1);
+        rc = __feat_register_nn(&dp->dccps_featneg, DCCPF_ACK_RATIO, 0,
+                                dmsk->dccpms_ack_ratio);
 out:
         return rc;
 }