dccp ccid-2: Separate internals of Ack Vectors from option-parsing code

This patch
 * separates Ack Vector housekeeping code from option-insertion code;
 * shifts option-specific code from ackvec.c into options.c;
 * introduces a dedicated routine to take care of the Ack Vector records;
 * simplifies the dccp_ackvec_insert_avr() routine: the BUG_ON was redundant, 
   since the list is automatically arranged in descending order of ack_seqno.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>

3 files changed, 80 insertions, 85 deletions

diff --git a/net/dccp/ackvec.c b/net/dccp/ackvec.c
index 85ad70cfba5b..de84dd34c93f 100644
--- a/net/dccp/ackvec.c
+++ b/net/dccp/ackvec.c
@@ -52,99 +52,35 @@ void dccp_ackvec_free(struct dccp_ackvec *av)
         }
 }
 
-static void dccp_ackvec_insert_avr(struct dccp_ackvec *av,
-                                   struct dccp_ackvec_record *avr)
-{
-        /*
-         * AVRs are sorted by seqno. Since we are sending them in order, we
-         * just add the AVR at the head of the list.
-         * -sorbo.
-         */
-        if (!list_empty(&av->av_records)) {
-                const struct dccp_ackvec_record *head =
-                                        list_entry(av->av_records.next,
-                                                   struct dccp_ackvec_record,
-                                                   avr_node);
-                BUG_ON(before48(avr->avr_ack_seqno, head->avr_ack_seqno));
-        }
-
-        list_add(&avr->avr_node, &av->av_records);
-}
-
-int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
+/**
+ * dccp_ackvec_update_records  -  Record information about sent Ack Vectors
+ * @av:         Ack Vector records to update
+ * @seqno:      Sequence number of the packet carrying the Ack Vector just sent
+ * @nonce_sum:  The sum of all buffer nonces contained in the Ack Vector
+ */
+int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seqno, u8 nonce_sum)
 {
-        struct dccp_sock *dp = dccp_sk(sk);
-        struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
-        /* Figure out how many options do we need to represent the ackvec */
-        const u8 nr_opts = DIV_ROUND_UP(av->av_vec_len, DCCP_SINGLE_OPT_MAXLEN);
-        u16 len = av->av_vec_len + 2 * nr_opts;
-        u8 i, nonce = 0;
-        const unsigned char *tail, *from;
-        unsigned char *to;
         struct dccp_ackvec_record *avr;
 
-        if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
-                return -1;
-
         avr = kmem_cache_alloc(dccp_ackvec_record_slab, GFP_ATOMIC);
         if (avr == NULL)
-                return -1;
-
-        DCCP_SKB_CB(skb)->dccpd_opt_len += len;
-
-        to   = skb_push(skb, len);
-        len  = av->av_vec_len;
-        from = av->av_buf + av->av_buf_head;
-        tail = av->av_buf + DCCPAV_MAX_ACKVEC_LEN;
-
-        for (i = 0; i < nr_opts; ++i) {
-                int copylen = len;
-
-                if (len > DCCP_SINGLE_OPT_MAXLEN)
-                        copylen = DCCP_SINGLE_OPT_MAXLEN;
-
-                /*
-                 * RFC 4340, 12.2: Encode the Nonce Echo for this Ack Vector via
-                 * its type; ack_nonce is the sum of all individual buf_nonce's.
-                 */
-                nonce ^= av->av_buf_nonce[i];
-
-                *to++ = DCCPO_ACK_VECTOR_0 + av->av_buf_nonce[i];
-                *to++ = copylen + 2;
-
-                /* Check if buf_head wraps */
-                if (from + copylen > tail) {
-                        const u16 tailsize = tail - from;
-
-                        memcpy(to, from, tailsize);
-                        to      += tailsize;
-                        len     -= tailsize;
-                        copylen -= tailsize;
-                        from    = av->av_buf;
-                }
-
-                memcpy(to, from, copylen);
-                from += copylen;
-                to   += copylen;
-                len  -= copylen;
-        }
+                return -ENOBUFS;
 
-        /*
-         * Each sent Ack Vector is recorded in the list, as per A.2 of RFC 4340.
-         */
-        avr->avr_ack_seqno  = DCCP_SKB_CB(skb)->dccpd_seq;
+        avr->avr_ack_seqno  = seqno;
         avr->avr_ack_ptr    = av->av_buf_head;
         avr->avr_ack_ackno  = av->av_buf_ackno;
-        avr->avr_ack_nonce  = nonce;
+        avr->avr_ack_nonce  = nonce_sum;
         avr->avr_ack_runlen = dccp_ackvec_runlen(av->av_buf + av->av_buf_head);
+        /*
+         * Since GSS is incremented for each packet, the list is automatically
+         * arranged in descending order of @ack_seqno.
+         */
+        list_add(&avr->avr_node, &av->av_records);
 
-        dccp_ackvec_insert_avr(av, avr);
-
-        dccp_pr_debug("%s ACK Vector 0, len=%d, ack_seqno=%llu, "
-                      "ack_ackno=%llu\n",
-                      dccp_role(sk), avr->avr_ack_runlen,
+        dccp_pr_debug("Added Vector, ack_seqno=%llu, ack_ackno=%llu (rl=%u)\n",
                       (unsigned long long)avr->avr_ack_seqno,
-                      (unsigned long long)avr->avr_ack_ackno);
+                      (unsigned long long)avr->avr_ack_ackno,
+                      avr->avr_ack_runlen);
         return 0;
 }
 
diff --git a/net/dccp/ackvec.h b/net/dccp/ackvec.h
index df18f9030dbb..b34e5ed4c342 100644
--- a/net/dccp/ackvec.h
+++ b/net/dccp/ackvec.h
@@ -112,7 +112,7 @@ extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
                              u64 *ackno, const u8 opt,
                              const u8 *value, const u8 len);
 
-extern int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb);
+extern int  dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum);
 
 static inline int dccp_ackvec_pending(const struct dccp_ackvec *av)
 {
@@ -155,8 +155,7 @@ static inline int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
         return -1;
 }
 
-static inline int dccp_insert_option_ackvec(const struct sock *sk,
-                                            const struct sk_buff *skb)
+static inline int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 nonce)
 {
         return -1;
 }
diff --git a/net/dccp/options.c b/net/dccp/options.c
index 9fe0510f4022..392d7db31342 100644
--- a/net/dccp/options.c
+++ b/net/dccp/options.c
@@ -428,6 +428,66 @@ static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp,
         return 0;
 }
 
+static int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
+{
+        struct dccp_sock *dp = dccp_sk(sk);
+        struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
+        /* Figure out how many options do we need to represent the ackvec */
+        const u8 nr_opts = DIV_ROUND_UP(av->av_vec_len, DCCP_SINGLE_OPT_MAXLEN);
+        u16 len = av->av_vec_len + 2 * nr_opts;
+        u8 i, nonce = 0;
+        const unsigned char *tail, *from;
+        unsigned char *to;
+
+        if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
+                return -1;
+
+        DCCP_SKB_CB(skb)->dccpd_opt_len += len;
+
+        to   = skb_push(skb, len);
+        len  = av->av_vec_len;
+        from = av->av_buf + av->av_buf_head;
+        tail = av->av_buf + DCCPAV_MAX_ACKVEC_LEN;
+
+        for (i = 0; i < nr_opts; ++i) {
+                int copylen = len;
+
+                if (len > DCCP_SINGLE_OPT_MAXLEN)
+                        copylen = DCCP_SINGLE_OPT_MAXLEN;
+
+                /*
+                 * RFC 4340, 12.2: Encode the Nonce Echo for this Ack Vector via
+                 * its type; ack_nonce is the sum of all individual buf_nonce's.
+                 */
+                nonce ^= av->av_buf_nonce[i];
+
+                *to++ = DCCPO_ACK_VECTOR_0 + av->av_buf_nonce[i];
+                *to++ = copylen + 2;
+
+                /* Check if buf_head wraps */
+                if (from + copylen > tail) {
+                        const u16 tailsize = tail - from;
+
+                        memcpy(to, from, tailsize);
+                        to      += tailsize;
+                        len     -= tailsize;
+                        copylen -= tailsize;
+                        from    = av->av_buf;
+                }
+
+                memcpy(to, from, copylen);
+                from += copylen;
+                to   += copylen;
+                len  -= copylen;
+        }
+        /*
+         * Each sent Ack Vector is recorded in the list, as per A.2 of RFC 4340.
+         */
+        if (dccp_ackvec_update_records(av, DCCP_SKB_CB(skb)->dccpd_seq, nonce))
+                return -ENOBUFS;
+        return 0;
+}
+
 /**
  * dccp_insert_option_mandatory  -  Mandatory option (5.8.2)
  * Note that since we are using skb_push, this function needs to be called