[HECnet] DECnet for Linux Bug Fixes

On Jun 30, 2020, at 10:29 AM, Gregg Levine <gregg.drwho8 at gmail.com> wrote: Hello! Something else, all of my PI devices, from one from Seven years ago last December to one that arrived perhaps two years previously are all 32 bit devices, the build-it instructions presuppose that a lot of us own Pi4 devices who're 64 bit capable. That card image the both of us are interested in would need to work on both style systems. ----- Gregg C Levine gregg.drwho8 at gmail.com "This signature fought the Time Wars, time and again."

On Tue, Jun 30, 2020 at 10:25 AM Gregg Levine <gregg.drwho8 at gmail.com> wrote: > > Hello! > How about he's right? I do know I could sit down in front of an SSH > terminal screen to an appropriate device and use the git tool to > download the code and follow the instructions that should be inside > the README file. However there must be some of us out on the list who > can do that, but would rather use a previously constructed image for > the purpose. > ----- > Gregg C Levine gregg.drwho8 at gmail.com > "This signature fought the Time Wars, time and again." > > On Tue, Jun 30, 2020 at 10:12 AM Supratim Sanyal <supratim at riseup.net> wrote: >> >> On 6/29/2020 20:45, John Forecast wrote: >> >> Recently I have found, and fixed, a number of bugs in the DECnet for Linux kernel module. Some of >> these bugs may be relevant for members of this mailing list who are using DECnet for Linux, >> especially on a Raspberry Pi. >> >> John - how about making our pandemic and politician-stressed lives a bit easier and uploading a microSD image somewhere relieving us from having to go through the hoops? >> >> https://github.com/JohnForecast/RaspbianDECnet/blob/master/README.Raspbian is fantastic, BTW. >> >> :) >> >> Regards >> Supratim >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> Major bugs fixed: >> >> - Ethernet Listen Timer was not implemented >> >> In addition, the check for an address change for the designated router (DR) was missing >> although there was a check if the DR?s priority had changed. >> >> Note: this code changes the format of /proc/net/decnet_dev to include the listen timer value. >> nml/nml2 needs to be rebuilt to understand the changed format. >> >> - System panic when using the loopback device (lo) >> >> The DECnet code was missing a destructor routine which is used to avoid data copying. >> >> - The neighbour (adjacent node) code could be broken by kernel changes >> >> The code made use of a now deprecated feature (zero length array at the end of a structure) >> in order to access data in a surrounding structure. This happened to work ?by chance? >> until kernel 5.4.42 on 32-bit processors. >> >> - Interrupt message flow control was broken >> >> The flow control was a mixture of using the SEND/DONTSEND status of the data >> subchannel and a message count. This seems to work between Linux systems but is broken >> when communicating with other systems - during the life of a logical link, the remote system >> could only send a single interrupt message while the Linux system could pretty much send >> as many interrupts as it wanted possibly overrunning the remote systems buffers. >> >> - Optional data on received connect confirm message was corrupted >> >> The code was getting the optional data from the wrong offset in the message. >> >> - Next hop cache problem >> >> 30 seconds after a logical link was taken down, the next hop cache entry was deleted. As >> part of this deletion, the link was taken ?down? which caused a neighbour entry to be >> created for the same node address but accessed via the loopback device. Sometimes this >> would cause the designated router to become accessible via the loopback device and >> subsequent connections would fail. >> >> - Intra-ethernet bit ignored >> >> The intra-ethernet bit in the routing flags is ignored on inbound traffic. If there was a neighbour >> entry for the remote node at connection time, everything would work correctly. If there wad no >> entry, all outbound traffic would be sent through the designated router for the duration of >> the logical link. >> >> - Promiscuous mode alters DECnet behaviour >> >> If the ethernet NIC used for DECnet had promiscuous mode enabled (e.g. using tcpdump >> for traffic tracing), the DECnet code would start seeing endnode hello?s, populating >> neighbour structures and causing the problems described above for the intra-ethernet bit >> to go away. >> >> New programs: >> >> DECnet Test Send and DECnet Test Receiver (DTS/DTR) >> >> Test programs created via reverse engineering the protocol exchanges. Used to find a >> number of the bugs described above. >> >> NML2 >> >> New implementation of the Network Management Listener. Supports SUMMARY, STATUS >> and CHARACTERISTICS for NODES, CIRCUITS and AREAS. It does not support LINKS >> and OBJECTS which were in the old version but are system specific operations which >> were only visible from DECnet-VMS systems. >> >> The old version is still the default during installation. The new version can be installed by: >> >> cd dnprogs/nml2 >> make >> sudo make install >> >> which will overwrite the installed executable and man page. >> >> OS Support: >> >> As of 06/29/2020 the code has been tested with: >> >> Raspbian 2020-05-27 release with kernels 4.19.126 and 5.4.44 (32-bit only) >> >> Pi OS 2020-05-27 32-bit release with kernel 4.19.126 and 5.4.44 >> >> pI OS 2020-05-27 (fully updated on 06/26/2020) with kernel 5.4.49 >> >> >> The source code and installation instructions are available at: >> >> <https://github.com/JohnForecast/RaspbianDECnet> >> >> John. >> >> -- >> Supratim Sanyal, W1XMT >> 39.19151 N, 77.23432 W >> QCOCAL::SANYAL via HECnet