[PATCH][BUG] Retransmission of "SYN+ACK" does'nt work

[Master Hirokazu Takahashi]

Hello,

I've checked the source to solve some problems and I just realize 
retransmission of "SYN+ACK" does'nt work well on linux v2.2.14.

Tere are two problems.

1) tcp_check_req() stops the "slow timer for SYN-RECV sockets"
   -- tcp_syn_recv_timer() -- even if it ignores to make 
   the TCP connection ESTABLISHED (the queue limit of pending
   connections might be over).
   "SYN+ACK packet" must be retranmitted again after a while.


2) tcp_close_pending() may over-decrease the counter of 
   the "slow timer for SYN-RECV sockets"
        (tcp_slt_array[TCP_SLT_SYNACK].count).
   Open_requests on the syn_wait_queue might be in
   ESTABLISHES status already.

   We can only call tcp_dec_slow_timer(TCP_SLT_SYNACK) for
   Not-ESTABLISHED connections.

   (Also ack_backlog count may be over-decreased.)


Here is a patch to fix them.


--- linux-2.2.14/net/ipv4/tcp.c Sun Apr 16 04:35:21 2000
+++ linux/net/ipv4/tcp.c        Sun Apr 16 04:40:44 2000
@@ -1484,15 +1484,18 @@
        while(req) {
                struct open_request *iter;
                
-               if (req->sk)
-                       tcp_close(req->sk, 0);
-
                iter = req;
                req = req->dl_next;
                
+               if (iter->sk) {
+                       tcp_close(iter->sk, 0);
+                       sk->ack_backlog--;
+               } else {
+                       tcp_dec_slow_timer(TCP_SLT_SYNACK);
+                       sk->tp_pinfo.af_tcp.syn_backlog--;
+               }
                (*iter->class->destructor)(iter);
-               tcp_dec_slow_timer(TCP_SLT_SYNACK);
-               sk->ack_backlog--;
+
                tcp_openreq_free(iter);
        }
 
--- linux-2.2.14/net/ipv4/tcp_input.c   Sun Apr 16 04:35:21 2000
+++ linux/net/ipv4/tcp_input.c  Sun Apr 16 04:40:44 2000
@@ -2012,10 +2012,10 @@
                }
        
                sk = tp->af_specific->syn_recv_sock(sk, skb, req, NULL);
-               tcp_dec_slow_timer(TCP_SLT_SYNACK);
                if (sk == NULL)
                        return NULL;
                
+               tcp_dec_slow_timer(TCP_SLT_SYNACK);
                req->expires = 0UL;
                req->sk = sk;
        }



Waiting for your comments.

Regards,
Hirokazu Takahashi
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