buglwIP - A Lightweight TCP/IP stack - Bugs: bug #65742, If no response is received to...

 
 

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bug #65742: If no response is received to close the TCP connection, tcp_pcb is released after 40 minutes

Submitter:  Jiri Engelthaler <engy>
Submitted:  Tue 14 May 2024 12:12:53 PM UTC
   
 
Category:  TCP Severity:  3 - Normal
Item Group:  None Status:  None
Privacy:  Public Assigned to:  None
Open/Closed:  Open Planned Release:  None
lwIP version:  2.2.0

Tue 14 May 2024 12:12:53 PM UTC, original submission:  

If no response is received to close the TCP connection, tcp_pcb is set to the FIN_WAIT_1 state, FIN is sent, and if no response is received, tcp_pcb is released after TCP_MAXRTX (12) retries. That is, after 40 minutes.

Tue May 14 04:57:32 2024 : tcp_connect to port 502
Tue May 14 04:57:32 2024 : tcp_output_segment: rtseq 6509
Tue May 14 04:57:35 2024 : tcp_receive: pcb->rttest 0 rtseq 6509 ackno 6510
Tue May 14 04:57:35 2024 : tcp_recved: received 6 bytes, wnd 20480 (0).
Tue May 14 04:57:35 2024 : tcp_fasttmr: delayed ACK
Tue May 14 04:57:55 2024 : tcp_close: closing in Tue May 14 04:57:55 2024 : State: ESTABLISHED
Tue May 14 04:57:55 2024 : tcp_output_segment: rtseq 6510
Tue May 14 04:57:57 2024 : tcp_slowtmr: rtime 6 pcb->rto 6
Tue May 14 04:57:57 2024 : tcp_output_segment: rtseq 6510
Tue May 14 04:58:03 2024 : tcp_slowtmr: rtime 12 pcb->rto 12
Tue May 14 04:58:03 2024 : tcp_output_segment: rtseq 6510
Tue May 14 04:58:16 2024 : tcp_slowtmr: rtime 24 pcb->rto 24
Tue May 14 04:58:16 2024 : tcp_output_segment: rtseq 6510
Tue May 14 04:58:40 2024 : tcp_slowtmr: rtime 48 pcb->rto 48
Tue May 14 04:58:40 2024 : tcp_output_segment: rtseq 6510
Tue May 14 04:59:29 2024 : tcp_slowtmr: rtime 96 pcb->rto 96
Tue May 14 04:59:29 2024 : tcp_output_segment: rtseq 6510
Tue May 14 05:01:08 2024 : tcp_slowtmr: rtime 192 pcb->rto 192
Tue May 14 05:01:08 2024 : tcp_output_segment: rtseq 6510
Tue May 14 05:04:26 2024 : tcp_slowtmr: rtime 384 pcb->rto 384
Tue May 14 05:04:26 2024 : tcp_output_segment: rtseq 6510
Tue May 14 05:11:02 2024 : tcp_slowtmr: rtime 768 pcb->rto 768
Tue May 14 05:11:02 2024 : tcp_output_segment: rtseq 6510
Tue May 14 05:17:38 2024 : tcp_slowtmr: rtime 768 pcb->rto 768
Tue May 14 05:17:38 2024 : tcp_output_segment: rtseq 6510
Tue May 14 05:24:14 2024 : tcp_slowtmr: rtime 768 pcb->rto 768
Tue May 14 05:24:14 2024 : tcp_output_segment: rtseq 6510
Tue May 14 05:30:51 2024 : tcp_slowtmr: rtime 768 pcb->rto 768
Tue May 14 05:30:51 2024 : tcp_output_segment: rtseq 6510
Tue May 14 05:37:26 2024 : tcp_slowtmr: rtime 768 pcb->rto 768
Tue May 14 05:37:26 2024 : tcp_output_segment: rtseq 6510
Tue May 14 05:37:26 2024 : tcp_slowtmr: max DATA retries reached
Tue May 14 05:37:26 2024 : tcp_pcb_purge
Tue May 14 05:37:26 2024 : tcp_pcb_purge: data left on ->unacked


The same problem occurs when sending data if the counterparty does not respond.

So is the default value of 12 for TCP_MAXRTX OK when it takes 40 minutes?

Jiri Engelthaler <engy>

 

(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

Attached Files
file #56049:  tcp_close.pcap added by engy (1KiB - application/octet-stream)

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -email is unavailable- added by engy (Submitted the item)
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    Follows 1 latest change.

    Date Changed by Updated Field Previous Value => Replaced by
    2024-05-14 engy Attached File- Added tcp_close.pcap, #56049

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