[HECnet] Intermittent Connection with PyDECnet?

[Robert Armstrong]

>    circuit tap-0 Ethernet tap:/dev/net/tap0

  FWIW, the "tap:" option in pyDECnet never worked for me.  I use pcap to
access tap devices -

	circuit TAP-0 Ethernet pcap:tap0 --single-address --cost=2

works for me with Ubuntu 18.04...

Bob



-----Original Message-----
From: owner-hecnet at Update.UU.SE [mailto:owner-hecnet at Update.UU.SE] On Behalf
Of Paul Koning
Sent: Monday, March 9, 2020 10:08 AM
To: hecnet at update.uu.se
Subject: Re: [HECnet] Intermittent Connection with PyDECnet?



> On Mar 9, 2020, at 12:47 PM, Mark J. Blair <nf6x at nf6x.net> wrote:
> 
> I made good progress yesterday on updating my home network setup. I
changed my home router/NAT/DHCP/DNS box from FreeBSD to Debian 10.3 "Buster"
for various reasons. It's routing and NATing and DHCPing and DNSing, and a
simh VAX-11/785 running OpenVMS 7.3 on it can talk DECnet phase IV to
another simh VAX-11/785 running on a BeagleBone Green (a small single-board
computer) on my LAN. The emulation running on the router connects to a tap
device, which is bridged to the physical ethernet interface for my LAN.
> 
> I've started trying to figure out how to run PyDECnet on the same router,
connected to another bridged tap. I haven't figured it out yet. My config
file looks like this:
> 
>    # DOGRTR config file for PyDECnet
>    circuit tap-0 Ethernet tap:/dev/net/tap0
>    routing 1.42 --type l1router
>    node 1.42 DOGRTR
>    node @nodenames.dat
>    system --identification "DOGRTR PyDECnet Router"
> 
> and the output when I launch it is:
> 
>    2020-03-09 09:43:26.278: MainThread: Starting DECnet/Python
DECnet/Python V1.0-487
>    2020-03-09 09:43:27.098: DOGRTR: No hardware address for Ethernet TAP-0
>    2020-03-09 09:43:27.099: DOGRTR: Event type 2.0, Local node state
change
>      From node 1.42 (DOGRTR), occurred 09-Mar-2020 09:43:27.099
>        Reason = Operator command
>        Old state = Off
>        New state = On
> 
> Does that look right?

I haven't used TAP in ages; when I need bridging I use Johnny's bridge.  But
the message ("No hardware address") means that PyDECnet tried to find out
the MAC address for the interface you mentioned and could not do so.  You
can avoid that by specifying an address explicitly.

> I've also tried the HTTP server, with this config:
> 
>    # DOGRTR config file for PyDECnet
>    circuit tap-0 Ethernet tap:/dev/net/tap0
>    node 1.42 DOGRTR
>    node @nodenames.dat
>    system --identification "DOGRTR PyDECnet Router"
>    http --https-port 0
> 
> When I connect to the web server, I get this console output:
> 
>    2020-03-09 09:45:22.344: MainThread: Starting DECnet/Python
DECnet/Python V1.0-487
>    2020-03-09 09:45:38.533: Thread-1: Exception handling http GET of /
>    Traceback (most recent call last):
>      File
"/usr/local/lib/python3.7/dist-packages/decnet-1.0-py3.7.egg/decnet/http.py"
, line 192, in do_GET
>        nodeidx, tnode, parts = self.findnode ()
>      File
"/usr/local/lib/python3.7/dist-packages/decnet-1.0-py3.7.egg/decnet/http.py"
, line 174, in findnode
>        return 0, nodelist[0], parts
>    IndexError: list index out of range
> 
> and this error in my browser:
> 
>    Error response
> 
>    Error code: 500
> 
>    Message: Internal Server Error.
> 
>    Error code explanation: 500 - Exception during server
processing.<p><pre>Traceback (most recent call last): File
"/usr/local/lib/python3.7/dist-packages/decnet-1.0-py3.7.egg/decnet/http.py"
, line 192, in do_GET nodeidx, tnode, parts = self.findnode () File
"/usr/local/lib/python3.7/dist-packages/decnet-1.0-py3.7.egg/decnet/http.py"
, line 174, in findnode return 0, nodelist[0], parts IndexError: list index
out of range </pre>.

The error handling clearly is bad here.  The issue is that you're using an
old config file pattern that is no longer valid.   I think I contributed to
this by not cleaning up old config examples until recently.

Some time ago I introduced the ability for a single PyDECnet process to run
multiple DECnet nodes (systems), and for that matter bridges as well.  This
is done by using a config file per system.  In the process, I didn't want
HTTP access to be per node, so I pulled it into a separate part of the
process.  The way it works (see doc/config.txt) is that you may have several
config files, and each contains an element that says what sort of thing it
defines.  Quoting config.txt:

  Each top level config file defines either a
  DECnet node (instance of "routing"), an Ethernet bridge, or the HTTP
  access feature.  So each config file must contain either a "routing",
  a "bridge", or an "http" component -- one but not more than one of
  these. 

So what happened is that you started PyDECnet with an HTTP server but
without nodes or bridges, so it has nothing to talk about.  The config lines
"circuit" and "node" and "system" are not relevant to the case of
configuring the HTTP server so they were ignored.

The bad error handling is that PyDECnet should complain if you didn't define
at least one node or bridge.  It would be nice if it also rejected lines
that aren't relevant (such as circuit definitions in an HTTP server config
file) but that's tricky because there isn't any order requirement for the
config lines.  In the example you gave, the type of config (http) isn't
given until the last line.

	paul