2 files changed, 33 insertions, 60 deletions

diff --git a/net/dccp/feat.h b/net/dccp/feat.h
index f8e4878dfc28..7efb2025f6bf 100644
--- a/net/dccp/feat.h
+++ b/net/dccp/feat.h
@@ -141,4 +141,6 @@ extern void dccp_encode_value_var(const u64 value, u8 *to, const u8 len);
 extern u64  dccp_decode_value_var(const u8 *bf, const u8 len);
 
 extern int  dccp_insert_option_mandatory(struct sk_buff *skb);
+extern int  dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
+                               u8 *val, u8 len, bool repeat_first);
 #endif /* _DCCP_FEAT_H */
diff --git a/net/dccp/options.c b/net/dccp/options.c
index 676d53065de9..bfa1cb8f3ef1 100644
--- a/net/dccp/options.c
+++ b/net/dccp/options.c
@@ -482,23 +482,46 @@ int dccp_insert_option_mandatory(struct sk_buff *skb)
         return 0;
 }
 
-static int dccp_insert_feat_opt(struct sk_buff *skb, u8 type, u8 feat,
-                                u8 *val, u8 len)
+/**
+ * dccp_insert_fn_opt  -  Insert single Feature-Negotiation option into @skb
+ * @type: %DCCPO_CHANGE_L, %DCCPO_CHANGE_R, %DCCPO_CONFIRM_L, %DCCPO_CONFIRM_R
+ * @feat: one out of %dccp_feature_numbers
+ * @val: NN value or SP array (preferred element first) to copy
+ * @len: true length of @val in bytes (excluding first element repetition)
+ * @repeat_first: whether to copy the first element of @val twice
+ * The last argument is used to construct Confirm options, where the preferred
+ * value and the preference list appear separately (RFC 4340, 6.3.1). Preference
+ * lists are kept such that the preferred entry is always first, so we only need
+ * to copy twice, and avoid the overhead of cloning into a bigger array.
+ */
+int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
+                       u8 *val, u8 len, bool repeat_first)
 {
-        u8 *to;
+        u8 tot_len, *to;
 
-        if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 3 > DCCP_MAX_OPT_LEN) {
-                DCCP_WARN("packet too small for feature %d option!\n", feat);
+        /* take the `Feature' field and possible repetition into account */
+        if (len > (DCCP_SINGLE_OPT_MAXLEN - 2)) {
+                DCCP_WARN("length %u for feature %u too large\n", len, feat);
                 return -1;
         }
 
-        DCCP_SKB_CB(skb)->dccpd_opt_len += len + 3;
+        if (unlikely(val == NULL || len == 0))
+                len = repeat_first = 0;
+        tot_len = 3 + repeat_first + len;
+
+        if (DCCP_SKB_CB(skb)->dccpd_opt_len + tot_len > DCCP_MAX_OPT_LEN) {
+                DCCP_WARN("packet too small for feature %d option!\n", feat);
+                return -1;
+        }
+        DCCP_SKB_CB(skb)->dccpd_opt_len += tot_len;
 
-        to    = skb_push(skb, len + 3);
+        to    = skb_push(skb, tot_len);
         *to++ = type;
-        *to++ = len + 3;
+        *to++ = tot_len;
         *to++ = feat;
 
+        if (repeat_first)
+                *to++ = *val;
         if (len)
                 memcpy(to, val, len);
 
@@ -508,51 +531,6 @@ static int dccp_insert_feat_opt(struct sk_buff *skb, u8 type, u8 feat,
         return 0;
 }
 
-static int dccp_insert_options_feat(struct sock *sk, struct sk_buff *skb)
-{
-        struct dccp_minisock *dmsk = dccp_msk(sk);
-        struct dccp_opt_pend *opt, *next;
-        int change = 0;
-
-        /* confirm any options [NN opts] */
-        list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
-                dccp_insert_feat_opt(skb, opt->dccpop_type,
-                                     opt->dccpop_feat, opt->dccpop_val,
-                                     opt->dccpop_len);
-                /* fear empty confirms */
-                if (opt->dccpop_val)
-                        kfree(opt->dccpop_val);
-                kfree(opt);
-        }
-        INIT_LIST_HEAD(&dmsk->dccpms_conf);
-
-        /* see which features we need to send */
-        list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
-                /* see if we need to send any confirm */
-                if (opt->dccpop_sc) {
-                        dccp_insert_feat_opt(skb, opt->dccpop_type + 1,
-                                             opt->dccpop_feat,
-                                             opt->dccpop_sc->dccpoc_val,
-                                             opt->dccpop_sc->dccpoc_len);
-
-                        BUG_ON(!opt->dccpop_sc->dccpoc_val);
-                        kfree(opt->dccpop_sc->dccpoc_val);
-                        kfree(opt->dccpop_sc);
-                        opt->dccpop_sc = NULL;
-                }
-
-                /* any option not confirmed, re-send it */
-                if (!opt->dccpop_conf) {
-                        dccp_insert_feat_opt(skb, opt->dccpop_type,
-                                             opt->dccpop_feat, opt->dccpop_val,
-                                             opt->dccpop_len);
-                        change++;
-                }
-        }
-
-        return 0;
-}
-
 /* The length of all options needs to be a multiple of 4 (5.8) */
 static void dccp_insert_option_padding(struct sk_buff *skb)
 {
@@ -589,13 +567,6 @@ int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
                 dp->dccps_hc_rx_insert_options = 0;
         }
 
-        /* Feature negotiation */
-        /* Data packets can't do feat negotiation */
-        if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA &&
-            DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATAACK &&
-            dccp_insert_options_feat(sk, skb))
-                return -1;
-
         /*
          * Obtain RTT sample from Request/Response exchange.
          * This is currently used in CCID 3 initialisation.