[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>

4 files changed, 40 insertions, 19 deletions

diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index fff794c8dfff..4efdce47000b 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -122,7 +122,8 @@ extern int  dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb);
 extern int dccp_send_response(struct sock *sk);
 extern void dccp_send_ack(struct sock *sk);
 extern void dccp_send_delayed_ack(struct sock *sk);
-extern void dccp_send_sync(struct sock *sk, u64 seq);
+extern void dccp_send_sync(struct sock *sk, const u64 seq,
+                           const enum dccp_pkt_type pkt_type);
 
 extern int dccp_write_xmit(struct sock *sk, struct sk_buff *skb,
                            const int len);
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;
         }
 
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index bc3cfc0533cc..335e00e9631d 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -376,7 +376,7 @@ static inline void dccp_do_pmtu_discovery(struct sock *sk,
                  *      probing, since DCCP-Sync probes do not risk application
                  *      data loss.
                  */
-                dccp_send_sync(sk, dp->dccps_gsr);
+                dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
         } /* else let the usual retransmit timer handle it */
 }
 
@@ -1008,7 +1008,7 @@ static inline int dccp_invalid_packet(struct sk_buff *skb)
                 return 1;
 
         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
-                dccp_pr_debug("pskb_may_pull failed\n");
+                printk(KERN_WARNING "DCCP: pskb_may_pull failed\n");
                 return 1;
         }
 
@@ -1016,7 +1016,7 @@ static inline int dccp_invalid_packet(struct sk_buff *skb)
 
         /* If the packet type is not understood, drop packet and return */
         if (dh->dccph_type >= DCCP_PKT_INVALID) {
-                dccp_pr_debug("invalid packet type\n");
+                printk(KERN_WARNING "DCCP: invalid packet type\n");
                 return 1;
         }
 
@@ -1025,12 +1025,13 @@ static inline int dccp_invalid_packet(struct sk_buff *skb)
          * packet, drop packet and return
          */
         if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
-                dccp_pr_debug("Offset(%u) too small 1\n", dh->dccph_doff);
+                printk(KERN_WARNING "DCCP: Offset(%u) too small 1\n",
+                       dh->dccph_doff);
                 return 1;
         }
 
         if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
-                dccp_pr_debug("P.Data Offset(%u) too small 2\n",
+                printk(KERN_WARNING "DCCP: P.Data Offset(%u) too small 2\n",
                               dh->dccph_doff);
                 return 1;
         }
@@ -1045,15 +1046,16 @@ static inline int dccp_invalid_packet(struct sk_buff *skb)
             dh->dccph_type != DCCP_PKT_DATA &&
             dh->dccph_type != DCCP_PKT_ACK &&
             dh->dccph_type != DCCP_PKT_DATAACK) {
-                dccp_pr_debug("P.type (%s) not Data, Ack nor DataAck and "
-                              "P.X == 0\n", dccp_packet_name(dh->dccph_type));
+                printk(KERN_WARNING "DCCP: P.type (%s) not Data, Ack nor "
+                                    "DataAck and P.X == 0\n",
+                       dccp_packet_name(dh->dccph_type));
                 return 1;
         }
 
         /* If the header checksum is incorrect, drop packet and return */
         if (dccp_v4_verify_checksum(skb, skb->nh.iph->saddr,
                                     skb->nh.iph->daddr) < 0) {
-                dccp_pr_debug("header checksum is incorrect\n");
+                printk(KERN_WARNING "DCCP: header checksum is incorrect\n");
                 return 1;
         }
 
diff --git a/net/dccp/output.c b/net/dccp/output.c
index dcc061bed924..384fd0920983 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -404,7 +404,8 @@ void dccp_send_delayed_ack(struct sock *sk)
         sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
 }
 
-void dccp_send_sync(struct sock *sk, u64 seq)
+void dccp_send_sync(struct sock *sk, const u64 seq,
+                    const enum dccp_pkt_type pkt_type)
 {
         /*
          * We are not putting this on the write queue, so
@@ -420,7 +421,7 @@ void dccp_send_sync(struct sock *sk, u64 seq)
         /* Reserve space for headers and prepare control bits. */
         skb_reserve(skb, MAX_DCCP_HEADER);
         skb->csum = 0;
-        DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_SYNC;
+        DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
         DCCP_SKB_CB(skb)->dccpd_seq = seq;
 
         skb_set_owner_w(skb, sk);