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ha5di / DIXPRS

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DIXPRS APRS-IS -> RF igate does not add correct TCPIP path, causing packet loops #2

Open hessu opened 7 years ago

hessu commented 7 years ago

Hi,

DIXPRS appears to implement a TX igate. When gating from APRS-IS to RF the packet path of the 3rd-party packet, after the '}', needs to be modified so that it has a ',TCPIP,IGATECALL*>' path, instead of the original path seen on APRS-IS. This will prevent those packets from getting igated back to the APRS-IS after the RF channel delay (1200 bit/s and digipeaters).

http://aprs-is.net/IGateDetails.aspx documents this requirement: "IGates must use the 3rd-party format on RF of IGATECALL>APRS,GATEPATH:}FROMCALL>TOCALL,TCPIP,IGATECALL*:original packet data where GATEPATH is the path that the gated packet is to follow on RF. This format will allow IGates to prevent gating the packet back to APRS-IS."

The looped-back duplicate packets are visible, for example, here: http://aprs.fi/?c=raw&limit=&call=F6BVP-10

2017-02-14 10:27:30 EET: F6BVP-10>APDI22,F5TUN-1,WIDE2-2,qAR,F5TUN:}F4GLJ>TYPQS4,qAR,F1PTL-3,qAR,F5KTR-3:`x5l#I-/`"4t}_% [Unsupported packet format]

F6BVP-10 (DIXPRS) has transmitted F4GLJ's packet back to RF, and then F5TUN has picked it up and looped it back to APRS-IS, due to the incorrect path.

Correct tx-igated packet would look like this (modified from the above example):

F6BVP-10>APDI22,F5TUN-1,WIDE2-2,qAR,F5TUN:}F4GLJ>TYPQS4,TCPIP,F6BCP-10:x*5l#I-/"4t}_%

The code path with the bug (missing feature) is shown here: https://github.com/ha5di/DIXPRS/blob/master/dixprs.py#L1125 https://github.com/ha5di/DIXPRS/blob/master/dixpcommon.py#L229 https://github.com/ha5di/DIXPRS/blob/master/dixpcommon.py#L217

Please look into fixing this, and increase the version number in the TOCALL (APDI22) of a version which fixes it, so that the igates with the fix can be identified more easily. Thank you!

Hessu, OH7LZB

hessu commented 7 years ago

Hi,

Just a gentle reminder about this bug. The bug is causing duplicate, delayed packets on the APRS network.

Thanks.

hessu commented 6 years ago

Hi,

Just a gentle reminder about this bug. The bug is causing duplicate, delayed packets on the APRS network.

Thanks.

iddq commented 6 years ago

can you please explain how the path should be modified? please show an example with original and modified path

hessu commented 1 year ago

@iddq The bug description already contains an original packet on APRS-IS, an example of the incorrectly formatted packet, and an example of a correctly modified packet path, after the phrase "Correct tx-igated packet would look like this (modified from the above example)".