[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>

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);

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;
 	}
 

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;
 	}
 

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);