Subj : SVDM - strange issue "already connected"
To   : deon
From : Digital Man
Date : Fri Aug 04 2023 12:17:08

  Re: SVDM - strange issue "already connected"
  By: deon to Digital Man on Fri Aug 04 2023 05:23 pm

 > Hey DM,
 >
 > Not sure if you recall, but earlier this year I was having some problems
 > with SVDM where after a while it would no longer connect.
 >
 > Not sure if this is related, but I discovered a repeatable issue today.
 >
 > In my svdm.ini file, I have an alias of
 >
 > 010003001=c-8-2.dege.lan:11179
 >
 > That host resolves to both an IPv4 and IPv6 address. I think windows is
 > prefering the IPv6 address when the resolver present both (although I'm not
 > 100% sure if that is correct), but when I replace the hostname with an IPv4
 > address - the problem below does *not* occur. (So its either an IPv6 thing,
 > or a resolver thing.)
 >
 > Anyway, if when my (dos) mailer is calling to my uplink, and it gets a
 > connection refused, the mailer (via SVDM) reports "NO CARRIER" (which I
 > think is expected).
 >
 > However, the next attempt results in SVDM reporting "ERROR" - regardless of
 > whether the uplink is back online or not. If I try and call in to the
 > mailer, I get SVDM responding "Sorry, not available right now".
 >
 > Using dbgview, I can see each attempt.
 >
 > The first failure:
 > 00000049        5:08:15 PM      [3472] SBBSVDM: RX command: ' ATD010003001 '
 > at 3035779
 > 00000050        5:08:15 PM      [3472] SBBSVDM: dial(010003001)
 > 00000051        5:08:15 PM      [3472] SBBSVDM: Connecting to port 11179 at
 > host 'c-8-2.dege.lan' via Raw
 > 00000052        5:08:15 PM      [3472] SBBSVDM:
 > C:\GitLab-Runner\builds\4S9KMgUy\2\main\sbbs\src\vdmodem\vdmodem.c 640
 > calling getaddrinfo
 > 00000053        5:08:15 PM      [3472] SBBSVDM:
 > C:\GitLab-Runner\builds\4S9KMgUy\2\main\sbbs\src\vdmodem\vdmodem.c 662
 > calling connect
 > 00000054        5:08:15 PM      [3472] SBBSVDM: Setting socket options
 > 00000055        5:08:15 PM      [3472] SBBSVDM: Socket send buffer length:
 > 8192 bytes
 > 00000056        5:08:15 PM      [3472] SBBSVDM: Socket receive buffer
 > length: 8192 bytes
 > 00000057        5:08:15 PM      [3472] SBBSVDM: Socket TCP_NODELAY: 0
 > 00000058        5:08:15 PM      [3472] SBBSVDM:
 > C:\GitLab-Runner\builds\4S9KMgUy\2\main\sbbs\src\vdmodem\vdmodem.c 710
 > socket_recvdone
 > 00000059        5:08:15 PM      [3472] SBBSVDM: Modem response: NO CARRIER
 >
 > The subsequent failure:
 >
 > 00000070        5:08:23 PM      [3472] SBBSVDM: RX command: ' ATD010003001 '
 > at 3043682
 > 00000071        5:08:23 PM      [3472] SBBSVDM: Can't dial: Already
 > connected 00000072        5:08:23 PM      [3472] SBBSVDM: Modem response:
 > ERROR
 >
 > IE: It is reporting "already connected" (when it isnt).

Thank you! That is very helpful.

 > The only way I can clear this is unload SVDM and reload it and then I'm good
 > to go until next time the uplink (only 1 uplink tested) is offline.

Looking at the code, this is a bug, but I also think an "ATH0" would have cleared this condition.

 > Thought you might like to know.
 >
 > (This is SVDM from 2a6d9983)

Thanks. I'll commit a fix in a second here, but nothing specifically for IPv6. Let me know if there remains some issue with the IPv6 support and I'll look into that.
-- 
                                            digital man (rob)

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