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netdisco/lib/App/Netdisco/Util/SNMP.pm
2017-11-15 22:32:29 +00:00

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package App::Netdisco::Util::SNMP;
use Dancer qw/:syntax :script/;
use App::Netdisco::Util::Permission ':all';
use base 'Exporter';
our @EXPORT = ();
our @EXPORT_OK = qw/
fixup_device_auth get_communities snmp_comm_reindex
/;
our %EXPORT_TAGS = (all => \@EXPORT_OK);
=head1 NAME
App::Netdisco::Util::SNMP
=head1 DESCRIPTION
Helper functions for L<SNMP::Info> instances.
There are no default exports, however the C<:all> tag will export all
subroutines.
=head1 EXPORT_OK
=head2 fixup_device_auth
Rebuilds the C<device_auth> config with missing defaults and other fixups for
config changes over time. Returns a list which can replace C<device_auth>.
=cut
sub fixup_device_auth {
my $config = (setting('device_auth') || setting('snmp_auth') || []);
my @new_stanzas = ();
# new style snmp config
foreach my $stanza (@$config) {
# user tagged
my $tag = '';
if (1 == scalar keys %$stanza) {
$tag = (keys %$stanza)[0];
$stanza = $stanza->{$tag};
# corner case: untagged lone community
if ($tag eq 'community') {
$tag = $stanza;
$stanza = {community => $tag};
}
}
# defaults
$stanza->{tag} ||= $tag;
$stanza->{read} = 1 if !exists $stanza->{read};
$stanza->{no} ||= [];
$stanza->{only} ||= ['any'];
die "error: config: snmpv2 community in device_auth must be single item, not list\n"
if ref $stanza->{community};
die "error: config: stanza in device_auth must have a tag\n"
if not $stanza->{tag} and exists $stanza->{user};
push @new_stanzas, $stanza
}
# legacy config
# note: read strings tried before write
# note: read-write is no longer used for read operations
push @new_stanzas, map {{
read => 1, write => 0,
no => [], only => ['any'],
community => $_,
}} @{setting('community') || []};
push @new_stanzas, map {{
write => 1, read => 0,
no => [], only => ['any'],
community => $_,
}} @{setting('community_rw') || []};
foreach my $stanza (@new_stanzas) {
$stanza->{driver} ||= 'snmp'
if exists $stanza->{community}
or exists $stanza->{user};
}
return @new_stanzas;
}
=head2 get_communities( $device, $mode )
Takes the current C<device_auth> setting and pushes onto the front of the list
the last known good SNMP settings used for this mode (C<read> or C<write>).
=cut
sub get_communities {
my ($device, $mode) = @_;
$mode ||= 'read';
my $seen_tags = {}; # for cleaning community table
my $config = (setting('device_auth') || []);
my @communities = ();
# first of all, use external command if configured
push @communities, _get_external_community($device, $mode)
if setting('get_community') and length setting('get_community');
# last known-good by tag
my $tag_name = 'snmp_auth_tag_'. $mode;
my $stored_tag = eval { $device->community->$tag_name };
if ($device->in_storage and $stored_tag) {
foreach my $stanza (@$config) {
if ($stanza->{tag} and $stored_tag eq $stanza->{tag}) {
push @communities, {%$stanza, only => [$device->ip]};
last;
}
}
}
# try last-known-good v2 read
push @communities, {
read => 1, write => 0, driver => 'snmp',
only => [$device->ip],
community => $device->snmp_comm,
} if defined $device->snmp_comm and $mode eq 'read';
# try last-known-good v2 write
my $snmp_comm_rw = eval { $device->community->snmp_comm_rw };
push @communities, {
write => 1, read => 0, driver => 'snmp',
only => [$device->ip],
community => $snmp_comm_rw,
} if $snmp_comm_rw and $mode eq 'write';
# clean the community table of obsolete tags
eval { $device->community->update({$tag_name => undef}) }
if not $stored_tag or !exists $seen_tags->{ $stored_tag };
return ( @communities, @$config );
}
sub _get_external_community {
my ($device, $mode) = @_;
my $cmd = setting('get_community');
my $ip = $device->ip;
my $host = $device->dns || $ip;
if (defined $cmd and length $cmd) {
# replace variables
$cmd =~ s/\%HOST\%/$host/egi;
$cmd =~ s/\%IP\%/$ip/egi;
my $result = `$cmd`; # BACKTICKS
return () unless defined $result and length $result;
my @lines = split (m/\n/, $result);
foreach my $line (@lines) {
if ($line =~ m/^community\s*=\s*(.*)\s*$/i) {
if (length $1 and $mode eq 'read') {
return map {{
read => 1,
only => [$device->ip],
community => $_,
}} split(m/\s*,\s*/,$1);
}
}
elsif ($line =~ m/^setCommunity\s*=\s*(.*)\s*$/i) {
if (length $1 and $mode eq 'write') {
return map {{
write => 1,
only => [$device->ip],
community => $_,
}} split(m/\s*,\s*/,$1);
}
}
}
}
return ();
}
=head2 snmp_comm_reindex( $snmp, $device, $vlan )
Takes an established L<SNMP::Info> instance and makes a fresh connection using
community indexing, with the given C<$vlan> ID. Works for all SNMP versions.
Passing VLAN "C<0>" (zero) will reset the indexing to the basic v2 community
or v3 empty context.
=cut
sub snmp_comm_reindex {
my ($snmp, $device, $vlan) = @_;
my $ver = $snmp->snmp_ver;
if ($ver == 3) {
my $prefix = '';
my @comms = get_communities($device, 'read');
# find a context prefix configured by the user
foreach my $c (@comms) {
next unless $c->{tag}
and $c->{tag} eq (eval { $device->community->snmp_auth_tag_read } || '');
$prefix = $c->{context_prefix} and last;
}
$prefix ||= 'vlan-';
debug
sprintf '[%s] reindexing to "%s%s" (ver: %s, class: %s)',
$device->ip, $prefix, $vlan, $ver, $snmp->class;
$vlan ? $snmp->update(Context => ($prefix . $vlan))
: $snmp->update(Context => '');
}
else {
my $comm = $snmp->snmp_comm;
debug sprintf '[%s] reindexing to vlan %s (ver: %s, class: %s)',
$device->ip, $vlan, $ver, $snmp->class;
$vlan ? $snmp->update(Community => $comm . '@' . $vlan)
: $snmp->update(Community => $comm);
}
}
true;