[DCCP] ackvec: infrastructure for sending more than one ackvec per packet

Commiter note:

This was split from Andrea's original patch, in the process I changed the type
of the ackvec index fields to u16 instead of to int and haven't folded
dccp_ackvec_parse with dccp_ackvec_check_rcv_ackno.

Next patch will actually do the insertion of more than one ackvec per packet,
using, initially, up to a max of 2 ackvecs as per Andrea's original patch, then
I'll work on support for larger ackvecs, be it using a sysctl or using
setsockopt.

Signed-off-by: Andrea Bittau <a.bittau@cs.ucl.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

3 files changed, 24 insertions, 20 deletions

diff --git a/net/dccp/ackvec.c b/net/dccp/ackvec.c
index 215355d993de..41d34d1babc1 100644
--- a/net/dccp/ackvec.c
+++ b/net/dccp/ackvec.c
@@ -169,13 +169,13 @@ void dccp_ackvec_free(struct dccp_ackvec *av)
 }
 
 static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av,
-                                   const u8 index)
+                                   const u32 index)
 {
         return av->dccpav_buf[index] & DCCP_ACKVEC_STATE_MASK;
 }
 
 static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av,
-                                 const u8 index)
+                                 const u32 index)
 {
         return av->dccpav_buf[index] & DCCP_ACKVEC_LEN_MASK;
 }
@@ -275,7 +275,7 @@ int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
                  *      could reduce the complexity of this scan.)
                  */
                 u64 delta = dccp_delta_seqno(ackno, av->dccpav_buf_ackno);
-                u8 index = av->dccpav_buf_head;
+                u32 index = av->dccpav_buf_head;
 
                 while (1) {
                         const u8 len = dccp_ackvec_len(av, index);
@@ -385,7 +385,7 @@ void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk,
 }
 
 static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av,
-                                            struct sock *sk, u64 ackno,
+                                            struct sock *sk, u64 *ackno,
                                             const unsigned char len,
                                             const unsigned char *vector)
 {
@@ -408,7 +408,7 @@ static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av,
                 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
                 u64 ackno_end_rl;
 
-                dccp_set_seqno(&ackno_end_rl, ackno - rl);
+                dccp_set_seqno(&ackno_end_rl, *ackno - rl);
 
                 /*
                  * If our AVR sequence number is greater than the ack, go
@@ -416,13 +416,13 @@ static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av,
                  */
                 list_for_each_entry_from(avr, &av->dccpav_records,
                                          dccpavr_node) {
-                        if (!after48(avr->dccpavr_ack_seqno, ackno))
+                        if (!after48(avr->dccpavr_ack_seqno, *ackno))
                                 goto found;
                 }
                 /* End of the dccpav_records list, not found, exit */
                 break;
 found:
-                if (between48(avr->dccpavr_ack_seqno, ackno_end_rl, ackno)) {
+                if (between48(avr->dccpavr_ack_seqno, ackno_end_rl, *ackno)) {
                         const u8 state = *vector & DCCP_ACKVEC_STATE_MASK;
                         if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) {
                                 dccp_pr_debug("%s ACK vector 0, len=%d, "
@@ -442,21 +442,20 @@ found:
                          */
                 }
 
-                dccp_set_seqno(&ackno, ackno_end_rl - 1);
+                dccp_set_seqno(ackno, ackno_end_rl - 1);
                 ++vector;
         }
 }
 
 int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
-                      const u8 opt, const u8 *value, const u8 len)
+                      u64 *ackno, const u8 opt, const u8 *value, const u8 len)
 {
-        if (len > DCCP_MAX_ACKVEC_LEN)
+        if (len > DCCP_MAX_ACKVEC_OPT_LEN)
                 return -1;
 
         /* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */
         dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk,
-                                        DCCP_SKB_CB(skb)->dccpd_ack_seq,
-                                        len, value);
+                                        ackno, len, value);
         return 0;
 }
 
diff --git a/net/dccp/ackvec.h b/net/dccp/ackvec.h
index d6a58db5fb13..96504a3b16e4 100644
--- a/net/dccp/ackvec.h
+++ b/net/dccp/ackvec.h
@@ -17,7 +17,9 @@
 #include <linux/types.h>
 
 /* Read about the ECN nonce to see why it is 253 */
-#define DCCP_MAX_ACKVEC_LEN 253
+#define DCCP_MAX_ACKVEC_OPT_LEN 253
+/* We can spread an ack vector across multiple options */
+#define DCCP_MAX_ACKVEC_LEN (DCCP_MAX_ACKVEC_OPT_LEN * 2)
 
 #define DCCP_ACKVEC_STATE_RECEIVED      0
 #define DCCP_ACKVEC_STATE_ECN_MARKED    (1 << 6)
@@ -51,8 +53,8 @@ struct dccp_ackvec {
         u64             dccpav_buf_ackno;
         struct list_head dccpav_records;
         struct timeval  dccpav_time;
-        u8              dccpav_buf_head;
-        u8              dccpav_vec_len;
+        u16             dccpav_buf_head;
+        u16             dccpav_vec_len;
         u8              dccpav_buf_nonce;
         u8              dccpav_ack_nonce;
         u8              dccpav_buf[DCCP_MAX_ACKVEC_LEN];
@@ -75,9 +77,9 @@ struct dccp_ackvec_record {
         struct list_head dccpavr_node;
         u64              dccpavr_ack_seqno;
         u64              dccpavr_ack_ackno;
-        u8               dccpavr_ack_ptr;
+        u16              dccpavr_ack_ptr;
+        u16              dccpavr_sent_len;
         u8               dccpavr_ack_nonce;
-        u8               dccpavr_sent_len;
 };
 
 struct sock;
@@ -96,7 +98,8 @@ extern int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
 extern void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
                                         struct sock *sk, const u64 ackno);
 extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
-                             const u8 opt, const u8 *value, const u8 len);
+                             u64 *ackno, const u8 opt,
+                             const u8 *value, const u8 len);
 
 extern int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb);
 
@@ -135,7 +138,8 @@ static inline void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
 }
 
 static inline int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
-                                    const u8 opt, const u8 *value, const u8 len)
+                                    const u64 *ackno, const u8 opt,
+                                    const u8 *value, const u8 len)
 {
         return -1;
 }
diff --git a/net/dccp/options.c b/net/dccp/options.c
index ee709ae0a97f..f398b43bc055 100644
--- a/net/dccp/options.c
+++ b/net/dccp/options.c
@@ -62,6 +62,7 @@ int dccp_parse_options(struct sock *sk, struct sk_buff *skb)
         struct dccp_sock *dp = dccp_sk(sk);
         const struct dccp_hdr *dh = dccp_hdr(skb);
         const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
+        u64 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
         unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
         unsigned char *opt_ptr = options;
         const unsigned char *opt_end = (unsigned char *)dh +
@@ -149,7 +150,7 @@ int dccp_parse_options(struct sock *sk, struct sk_buff *skb)
                                 break;
 
                         if (dccp_msk(sk)->dccpms_send_ack_vector &&
-                            dccp_ackvec_parse(sk, skb, opt, value, len))
+                            dccp_ackvec_parse(sk, skb, &ackno, opt, value, len))
                                 goto out_invalid_option;
                         break;
                 case DCCPO_TIMESTAMP: