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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2008-07-26 14:59:09 +0400
committerGerrit Renker <gerrit@erg.abdn.ac.uk>2008-07-26 14:59:09 +0400
commit59435444a13ed52d3444c5df26b73d3086bcd57b (patch)
tree72846dbcb8c6c41e6d630bcb81297801dfe7fb16 /net/dccp/output.c
parentcdec7e50a4896c5197d5575d9ca635eea6825149 (diff)
downloadlinux-59435444a13ed52d3444c5df26b73d3086bcd57b.tar.xz
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>
Diffstat (limited to 'net/dccp/output.c')
-rw-r--r--net/dccp/output.c20
1 files changed, 16 insertions, 4 deletions
diff --git a/net/dccp/output.c b/net/dccp/output.c
index fe20068c5d8e..d19d48195013 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -284,14 +284,26 @@ void dccp_write_xmit(struct sock *sk, int block)
}
}
-int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
+/**
+ * dccp_retransmit_skb - Retransmit Request, Close, or CloseReq packets
+ * There are only four retransmittable packet types in DCCP:
+ * - Request in client-REQUEST state (sec. 8.1.1),
+ * - CloseReq in server-CLOSEREQ state (sec. 8.3),
+ * - Close in node-CLOSING state (sec. 8.3),
+ * - Acks in client-PARTOPEN state (sec. 8.1.5, handled by dccp_delack_timer()).
+ * This function expects sk->sk_send_head to contain the original skb.
+ */
+int dccp_retransmit_skb(struct sock *sk)
{
+ WARN_ON(sk->sk_send_head == NULL);
+
if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk) != 0)
return -EHOSTUNREACH; /* Routing failure or similar. */
- return dccp_transmit_skb(sk, (skb_cloned(skb) ?
- pskb_copy(skb, GFP_ATOMIC):
- skb_clone(skb, GFP_ATOMIC)));
+ /* this count is used to distinguish original and retransmitted skb */
+ inet_csk(sk)->icsk_retransmits++;
+
+ return dccp_transmit_skb(sk, skb_clone(sk->sk_send_head, GFP_ATOMIC));
}
struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,