dccp: Allow to distinguish original and retransmitted packets
This patch allows the sender to distinguish original and retransmitted packets,
which is in particular needed for the retransmission of DCCP-Requests:
* the first Request uses ISS (generated in net/dccp/ip*.c), and sets GSS = ISS;
* all retransmitted Requests use GSS' = GSS + 1, so that the n-th retransmitted
Request has sequence number ISS + n (mod 48).
To add generic support, the patch reorganises existing code so that:
* icsk_retransmits == 0 for the original packet and
* icsk_retransmits = n > 0 for the n-th retransmitted packet
at the time dccp_transmit_skb() is called, via dccp_retransmit_skb().
Thanks to Wei Yongjun for pointing this problem out.
Further changes:
----------------
* removed the `skb' argument from dccp_retransmit_skb(), since sk_send_head
is used for all retransmissions (the exception is client-Acks in PARTOPEN
state, but these do not use sk_send_head);
* since sk_send_head always contains the original skb (via dccp_entail()),
skb_cloned() never evaluated to true and thus pskb_copy() was never used.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
diff --git a/net/dccp/timer.c b/net/dccp/timer.c
index 6a5b961..54b3c7e 100644
--- a/net/dccp/timer.c
+++ b/net/dccp/timer.c
@@ -99,21 +99,11 @@
}
/*
- * sk->sk_send_head has to have one skb with
- * DCCP_SKB_CB(skb)->dccpd_type set to one of the retransmittable DCCP
- * packet types. The only packets eligible for retransmission are:
- * -- Requests in client-REQUEST state (sec. 8.1.1)
- * -- Acks in client-PARTOPEN state (sec. 8.1.5)
- * -- CloseReq in server-CLOSEREQ state (sec. 8.3)
- * -- Close in node-CLOSING state (sec. 8.3) */
- WARN_ON(sk->sk_send_head == NULL);
-
- /*
* More than than 4MSL (8 minutes) has passed, a RESET(aborted) was
* sent, no need to retransmit, this sock is dead.
*/
if (dccp_write_timeout(sk))
- goto out;
+ return;
/*
* We want to know the number of packets retransmitted, not the
@@ -122,30 +112,28 @@
if (icsk->icsk_retransmits == 0)
DCCP_INC_STATS_BH(DCCP_MIB_TIMEOUTS);
- if (dccp_retransmit_skb(sk, sk->sk_send_head) < 0) {
+ if (dccp_retransmit_skb(sk) != 0) {
/*
* Retransmission failed because of local congestion,
* do not backoff.
*/
- if (icsk->icsk_retransmits == 0)
+ if (--icsk->icsk_retransmits == 0)
icsk->icsk_retransmits = 1;
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
min(icsk->icsk_rto,
TCP_RESOURCE_PROBE_INTERVAL),
DCCP_RTO_MAX);
- goto out;
+ return;
}
backoff:
icsk->icsk_backoff++;
- icsk->icsk_retransmits++;
icsk->icsk_rto = min(icsk->icsk_rto << 1, DCCP_RTO_MAX);
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto,
DCCP_RTO_MAX);
if (icsk->icsk_retransmits > sysctl_dccp_retries1)
__sk_dst_reset(sk);
-out:;
}
static void dccp_write_timer(unsigned long data)