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>

diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
index 9a430734530c6d8bd2079ca7c1662d03b221ad73..c9ea19a4d85e10b0ba8c5a2a4d8c27b2496bc79b 100644 (file)
--- a/net/dccp/ccids/ccid2.c
+++ b/net/dccp/ccids/ccid2.c
@@ -25,7 +25,7 @@
 /*
  * This implementation should follow RFC 4341
  */
-
+#include "../feat.h"
 #include "../ccid.h"
 #include "../dccp.h"
 #include "ccid2.h"
@@ -147,8 +147,8 @@ static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
                DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio);
                val = max_ratio;
        }
-       if (val > 0xFFFF)               /* RFC 4340, 11.3 */
-               val = 0xFFFF;
+       if (val > DCCPF_ACK_RATIO_MAX)
+               val = DCCPF_ACK_RATIO_MAX;
 
        if (val == dp->dccps_l_ack_ratio)
                return;

diff --git a/net/dccp/feat.c b/net/dccp/feat.c
index 77ce2f6b0319a8bd1016818d871b0bf9b9086254..b859722fba72f619448f0f80c33ae5279fe0db63 100644 (file)
--- 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;
 }

diff --git a/net/dccp/feat.h b/net/dccp/feat.h
index 7e953fd0a79bb6177eb93c37739874bfdd296035..9eefdb43783efa9914a8bd7ff2d91edffd7a08ee 100644 (file)
--- a/net/dccp/feat.h
+++ b/net/dccp/feat.h
@@ -14,6 +14,15 @@
 #include <linux/types.h>
 #include "dccp.h"
 
+/*
+ * Known limit values
+ */
+/* Ack Ratio takes 2-byte integer values (11.3) */
+#define DCCPF_ACK_RATIO_MAX    0xFFFF
+/* Wmin=32 and Wmax=2^46-1 from 7.5.2 */
+#define DCCPF_SEQ_WMIN         32
+#define DCCPF_SEQ_WMAX         0x3FFFFFFFFFFFull
+
 enum dccp_feat_type {
        FEAT_AT_RX   = 1,       /* located at RX side of half-connection  */
        FEAT_AT_TX   = 2,       /* located at TX side of half-connection  */
@@ -74,6 +83,20 @@ static inline u8 dccp_feat_genopt(struct dccp_feat_entry *entry)
        return entry->is_local ? DCCPO_CHANGE_L : DCCPO_CHANGE_R;
 }
 
+/**
+ * struct ccid_dependency  -  Track changes resulting from choosing a CCID
+ * @dependent_feat: one of %dccp_feature_numbers
+ * @is_local: local (1) or remote (0) @dependent_feat
+ * @is_mandatory: whether presence of @dependent_feat is mission-critical or not
+ * @val: corresponding default value for @dependent_feat (u8 is sufficient here)
+ */
+struct ccid_dependency {
+       u8      dependent_feat;
+       bool    is_local:1,
+               is_mandatory:1;
+       u8      val;
+};
+
 #ifdef CONFIG_IP_DCCP_DEBUG
 extern const char *dccp_feat_typename(const u8 type);
 extern const char *dccp_feat_name(const u8 feat);
@@ -96,6 +119,6 @@ extern int  dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
 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 dccp_minisock *dmsk);
+extern int  dccp_feat_init(struct sock *sk);
 
 #endif /* _DCCP_FEAT_H */

diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index dafcefd865948dd42407d5fbb586fd7fdcad0af8..01332fe7a99a5003917e29962f5e0109973cdbab 100644 (file)
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -202,7 +202,7 @@ int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized)
         * setsockopt(CCIDs-I-want/accept). -acme
         */
        if (likely(ctl_sock_initialized)) {
-               int rc = dccp_feat_init(dmsk);
+               int rc = dccp_feat_init(sk);
 
                if (rc)
                        return rc;