This module will parse a Zone File and put all the Resource Records (RRs) into an anonymous hash
structure. Various record types are supported, see the methods section for details. It could be useful
for maintaining DNS zones, or for transferring DNS zones to other servers. If you want to generate an
XML-friendly version of your zone files, it is easy to use XML::Simple with this module once you have
parsed the zone file.
DNS::ZoneParse scans the DNS zone file - removes comments and seperates the file into its constituent
records. It then parses each record and stores the records internally. See below for information on the
accessor methods.
METHODS
new This creates the DNS::ZoneParse object and loads the zone file.
Example:
my $zonefile = DNS::ZoneParse->new("/path/to/zonefile.db");
You can also initialise the object with the contents of a file:
my $zonefile = DNS::ZoneParse->new( \$zone_contents );
You can pass a second, optional parameter to the constructor to supply an $origin if none can be
found in the zone file.
my $zonefile = DNS::ZoneParse->new( \$zone_contents, $origin );
You can pass a third, optional parameter to the constructor to supply a callback which will be called
whenever an unparsable line is encountered in the zone file. See "on_unparseable_line" for details on
this parameter and how errors are handled when parsing zone files.
If you plan to pass a on_unparseable_line callback but do not wish to specify an $origin, pass
'undef' as the $origin parameter.
a(), cname(), srv(), mx(), ns(), ptr(), txt(), hinfo(), rp(), loc()
These methods return references to the resource records. For example:
my $mx = $zonefile->mx;
Returns the mx records in an array reference.
All records (except SOA) have the following properties: 'ttl', 'class', 'host', 'name', 'ORIGIN'.
MX records also have a 'priority' property.
SRV records also have 'priority', 'weight' and 'port' properties.
TXT records also have a 'text' property representing the record's 'txt-data' descriptive text.
HINFO records also have 'cpu' and 'os' properties.
RP records also have 'mbox' and 'text' properties.
LOC records also have 'd1', 'm1', 's1', 'NorS', 'd2', 'm2', 's2', 'EorW', 'alt', 'siz', 'hp', and
'vp', as per RFC 1876.
If there are no records of a given type in the zone, the call will croak with an error message about
an invalid method. (This is not an ideal behavior, but has been kept for backwards compatibility.)
The 'ORIGIN' property is the fully-qualified origin of the record. See fqname for details on
constructing a fully qualified domain name. Note: for SOA records, the 'ORIGIN' will match the
'origin' property when the SOA record is specified as fully qualified.
soa()
Returns a hash reference with the following properties: 'serial', 'origin', 'primary', 'refresh',
'retry', 'ttl', 'minimumTTL', 'email', 'expire', 'class', 'ORIGIN'.
The 'ORIGIN' property is returned separate from 'origin' property, though the data may be the same.
'ORIGIN' represents the implicit origin for the record while 'origin' represents the origin specified
on the SOA line in the file.
If the 'origin' value is relative (that is, does not end with a '.'), the actual zone for which the
SOA line applies must be computed by concatenating the 'origin' and 'ORIGIN' values. See fqname for
details. If the 'origin' value is absolute, no computation is necessary and 'origin' is the same as
'ORIGIN'.
generate()
Returns an array of hashes representing $GENERATE directives present in the zone. Note, $GENERATE
directives are BIND-specific additions. They are not expanded by DNS::ZoneParse, but users are able
to access and modify these directives. The following properties are returned:
'range', 'lhs', 'ttl', 'class', 'type', 'rhs', 'ORIGIN'.
See the BIND documentation for details on the syntax and usage of the $GENERATE directive.
dump
Returns a copy of the datastructute that stores all the resource records. This might be useful if you
want to quickly transform the data into another format, such as XML.
fqname
Takes a single parameter, a hash reference containing a record.
Returns the fully qualified name of this record, with a trailing '.'. In most cases this is as simple
as concatenating the 'name' and 'ORIGIN' with a '.' unless 'name' is '@', in which case the fqname
is simply the 'ORIGIN'. For SOA records, the same process is performed on the 'origin' instead of
'name'.
Please note, fqname will not expand the right hand side of a record (ie, CNAME, SOA, MX, etc). The
user must expand these values via the above method.
ttl_to_int
Takes a single parameter, a string representing a valid record TTL.
Returns an integer representing the number of seconds the TTL represents. Note, this does not take
into account any leap-years, leap-seconds, DST changes, etc. It is simply the count of the number of
seconds in the specified period of time.
new_serial
"new_serial()" incriments the Zone serial number. It will generate a date-based serial number. Or you
can pass a positive number to add to the current serial number.
Examples:
$zonefile->new_serial();
# generates a new serial number based on date:
# YYYYmmddHH format, incriments current serial
# by 1 if the new serial is still smaller
$zonefile->new_serial(50);
# adds 50 to the original serial number
output
"output()" returns the new zone file output as a string. If you wish your output formatted
differently, you can pass the output of "dump()" to your favourite templating module.
last_parse_error_count
Returns a count of the number of unparsable lines from the last time a zone file was parsed. If no
zone file has been parsed yet, returns 0.
If you want to be sure that a zone file was parsed completely and without error, the return value of
this method should be checked after the constructor is called (or after a call to _parse).
on_unparseable_line
"on_unparseable_line()" is an accessor method for the callback used when an unparseable line is
encountered while parsing a zone file. If not set, DNS::ZoneParse will "croak" when an unparsable
line is encountered, but will continue to parse the file. Each time an unparsable line is
encountered, an internal counter is incrememnted. See "last_parse_error_count" for details.
The callback is passed four parameters, a reference to the DNS::ZoneParse object which is doing the
parsing, the text of the line that is unable to be parsed, the text of the reason the line could not
be parsed, and the text of the last successfully parsed line.
If you want to abort parsing when an unparsable line is found, call "die" from within your callback
and catch that die with an eval block around the DNS::ZoneParse constructor (or call to _parse).
The method takes a single optional parameter, a code reference to the function that will be called
when an unparsable line is reached. Returns a reference to the last callback. If passed an undefined
value, a reference to the current callback is returned. If passed any other value, undef is returned.
EXAMPLES
This script will print the A records in a zone file, add a new A record for the name "new" and then
return the zone file.
use strict;
use DNS::ZoneParse;
my $zonefile = DNS::ZoneParse->new("/path/to/zonefile.db");
print "Current A Records\n";
my $a_records = $zonefile->a();
foreach my $record (@$a_records) {
print "$record->{name} resolves at $record->{host}\n";
}
push (@$a_records, { name => 'new', class => 'IN',
host => '127.0.0.1', ttl => '' });
$zonefile->new_serial();
my $newfile = $zonefile->output();
This script will convert a DNS Zone file to an XML file using XML::Simple.
use strict;
use DNS::ZoneParse;
use XML::Simple;
my $zonefile = DNS::ZoneParse->new("/path/to/zonefile.db");
my $new_xml = XMLout($zonefile->dump,
noattr => 1,
suppressempty => 1,
rootname => $zonefile->origin);
Install Now
PNG Icons
