[DCCP]: Send SYNCACK packets in response to SYNC packets

Also fix step 6 when receiving SYNC or SYNCACK packets, i.e. we were not using
the updated swl.

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 25 insertions, 8 deletions

diff --git a/net/dccp/input.c b/net/dccp/input.c
index 9dadfc362511..68b6e72551ef 100644
--- a/net/dccp/input.c
+++ b/net/dccp/input.c
@@ -50,7 +50,7 @@ static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
          *        Drop packet and return
          */
         if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
-                dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
+                dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
                 return;
         }
 
@@ -76,8 +76,7 @@ static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
 {
         const struct dccp_hdr *dh = dccp_hdr(skb);
         struct dccp_sock *dp = dccp_sk(sk);
-        u64 lswl = dp->dccps_swl;
-        u64 lawl = dp->dccps_awl;
+        u64 lswl, lawl;
 
         /*
          *   Step 5: Prepare sequence numbers for Sync
@@ -99,6 +98,8 @@ static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
                         dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
                 else
                         return -1;
+        }
+        
         /*
          *   Step 6: Check sequence numbers
          *      Let LSWL = S.SWL and LAWL = S.AWL
@@ -113,7 +114,10 @@ static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
          *        Send Sync packet acknowledging P.seqno
          *        Drop packet and return
          */
-        } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
+        lswl = dp->dccps_swl;
+        lawl = dp->dccps_awl;
+
+        if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
                    dh->dccph_type == DCCP_PKT_CLOSE ||
                    dh->dccph_type == DCCP_PKT_RESET) {
                 lswl = dp->dccps_gsr;
@@ -132,8 +136,8 @@ static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
                      DCCP_PKT_WITHOUT_ACK_SEQ))
                         dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq;
         } else {
-                dccp_pr_debug("Step 6 failed, sending SYNC...\n");
-                dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
+                LIMIT_NETDEBUG("Step 6 failed, sending SYNC...\n");
+                dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
                 return -1;
         }
 
@@ -242,9 +246,21 @@ int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
 check_seq:
                 if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) {
 send_sync:
-                        dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
+                        dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
+                                       DCCP_PKT_SYNC);
                 }
                 break;
+        case DCCP_PKT_SYNC:
+                dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
+                               DCCP_PKT_SYNCACK);
+                /*
+                 * From the draft:
+                 *
+                 * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
+                 * MAY have non-zero-length application data areas, whose
+                 * contents * receivers MUST ignore.
+                 */
+                goto discard;
         }
 
         DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
@@ -517,7 +533,8 @@ int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
                      dh->dccph_type == DCCP_PKT_REQUEST) ||
                     (sk->sk_state == DCCP_RESPOND &&
                      dh->dccph_type == DCCP_PKT_DATA)) {
-                dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
+                dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
+                               DCCP_PKT_SYNC);
                 goto discard;
         }