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SNMP-OID-Translate-0.0005
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SNMP::OID::Translate - nothing but translateObj

This is a stripped copy of the perl SNMP.pm XS module. It comes from version 5.0404. The reason for this is because I'm using Net::SNMP for everything except translateObj, but SNMP.pm is nearly impossible to build in a way that travis+perlbrew are happy with.

Synopsis

use SNMP::OID::Translate;
my $output = SNMP::OID::Translate::translateObj($input);

Special hacks needed for this module

Removed net-snmp-config usage

This will probably break some OS but it cleans the Makefile and makes it work better under perlbrew. I only anticipate this causing an issue on (possibly) windows.

Added MIBS environment variable

We also need to say MIBS=+IF-MIB in environment to get it to load a MIB for testing.

Code changes behind the scenes

Got rid of $` and $&

Because these can be slow on older perl it's better to avoid them. Especially since it slows down any regex after they are used.

Things I tried before doing this

This is an incomplete list of things I've tried. I'm including them in case they help others in similar quests.

Copying system modules over to perlbrew

find /usr -name "SNMP.pm" -exec cp {} $HOME/perl5/lib/perl5 \; -quit

The problem with this approach is if there are other SNMP modules installed, like AnyEvent::SNMP, it can't detect which one is the right SNMP.pm.

So how about:

find /usr -name '*[0-9]/SNMP.pm' -exec cp {} $HOME/perl5/lib/perl5 \; -quit

That assumes the directory is going to be called /5.20/ or whatever the perl version is. It might break with dev/blead releases and other things.

So let's make perl find the module

We could use Module::Find, except our "before_install" commands run long after we're switched into perlbrew, so our @INC space wouldn't include the normal system @INC.

but the system perl is in an easy to find place.. so let's try this:

- "cp $(/usr/bin/perl $(which mpath) SNMP) $HOME/perl5/lib/perl5"

Testing this locally seems to work, so now we just need to see if we've made travis happy.

* E: Unable to locate package libmodule-path-perl

ok, we can fix that by running "cpanm Module::Path"

next run

* Can't locate Module/Path.pm in @INC (@INC contains: /etc/perl

So we're not looking in the local directories when using the system perl. Let's see if we can get cpanm to install into a system directory using "sudo cpanm Module::Path"

next run

* sudo: cpanm: command not found

(╯°□°)╯︵ ┻━┻

Lets hardcode more paths. I went ahead and overrode perl to make sure cpanm would see the system's @INC instead of the local one.

sudo /usr/bin/perl $HOME/perl5/perlbrew/bin/cpanm Module::Path

next run

* cp: cannot create regular file `/home/travis/perl5/lib/perl5': No such file or directory

So hardcoding the destination path wasn't a good idea either

cp $(/usr/bin/perl $(which mpath) SNMP) $(perl -E 'say @INC[0]')

next run

* Error:  Can't locate GD/Image.pm in @INC

Wow.. finally, tests are running. But we still failed because it couldn't find some submodules we didn't copy.

SNMP is a single file so it might run on it's own.

after adding some tests for SNMP.pm we get more module failures

Turns out SNMP isn't a single file. They have a second module in a different namespace for unexplainable reasons (probably historic).

- "cp -r $(dirname $(/usr/bin/perl $(which mpath) NetSNMP/default_store.pm)) $(perl -E 'say @INC[0]')"

and again...

Can't locate auto/NetSNMP/default_store/autosplit.ix

At this point I think we should get off the tangent of trying to fix perlbrew with file copying and attempt to do things the right way again, by building the module.

trying to build the module with env var

Once i had a chance to download the SNMP.pm module source and build-deps, I saw there is a flag to ignore the version difference and run anyway. This would probably work for us since we only want translateObj.

env:
  - NETSNMP_DONT_CHECK_VERSION=1

So I did this. SNMP still bombed. Attempting to troubleshoot here I found that even with "apt-get build-deps SNMP" you don't get enough of net-snmp to build the module.

turns out we need libsnmp-dev

This gives us net-snmp-config and some other files which are important to building.

Now we're failing SNMP.pm tests because snmpd isn't found

cpanm --notest SNMP

the module installs and is unusable

t/10-snmp.t ............. Can't locate NetSNMP/default_store.pm in @INC (you may need to install the NetSNMP::default_store module)

Somehow installing libsnmp-perl fixes this (at least on my machine, I don't think I tried it with travis)

But then we get to another error:

Can't load '/home/rdrake/perl5/lib/perl5/x86_64-linux-gnu-thread-multi/auto/SNMP/SNMP.so' for module SNMP: /home/rdrake/perl5/lib/perl5/ x86_64-linux-gnu-thread-multi/auto/SNMP/SNMP.so: undefined symbol: memdup at /usr/lib/x86_64-linux-gnu/perl/5.22/DynaLoader.pm line 187.

I think this (and maybe the previous problem) are caused by the mismatched versions. More specifically, I think the version shipped with debian might be newer than what is on CPAN.

asking cpanm to install the same version as debian doesn't work

cpanm --notest SNMP@$(perl -MSNMP -e 'print $SNMP::VERSION')
Found SNMP 5.0404 which doesn't satisfy == 5.0703.

my final travis.yml

language: perl
sudo: true

env:
  - NETSNMP_DONT_CHECK_VERSION=1
before_install:
    - "sudo apt-get -yq update"
    - "sudo apt-get -yq install libsnmp-perl libsnmp-dev"
    - "cpanm --notest SNMP"
    - eval $(curl https://travis-perl.github.io/init) --auto

perl:
    - "5.20"
    - "5.18"
    - "5.16"
    - "5.14"

matrix:
  include:
    - perl: 5.18
      env: COVERAGE=1   # enables coverage+coveralls reporting
  allow_failures:
    - perl: blead       # ignore failures for blead perl
    - perl: dev         # ignore failures for dev perl

Note that this still doesn't work, but it might be a starting point for someone who doesn't want to commit 40 times attempting to make this happen.

TODO

Changing strcpy and sprintf to strncopy/snprintf

Even though I'm reasonably sure the code is safe after looking at how they're used, I would rather not leave them because of the possibility of a refactor that overruns a buffer without checking.

Final notes

  1. The SNMP.pm module should either be removed from CPAN or every available version should be uploaded so that we can pull a compatible version. The fact that Net-SNMP ships with the correctly syncronized version means it's of dubious benefit to keep it on CPAN.

  2. NetSNMP::default_store doesn't make use of autosplit. I believe "use AutoLoader" should be removed from the module.