NAME

Net::Bind::Resolv - a class to munge /etc/resolv.conf data.

SYNOPSIS

use Net::Bind::Resolv;

DESCRIPTION

This class provides an object oriented perl interface to /etc/resolv.conf data.

Here is an example snippet of code:

  use Net::Bind::Resolv;
  my $res = new Net::Bind::Resolv('/etc/resolv.conf');
  print $res->domain, "\n";

Or how about:

  use Net::Bind::Resolv;
  use IO::File;
  my $res = new Net::Bind::Resolv;
  $res->comment("Programmatically generated\nDo not edit by hand");
  $res->domain('arf.fz');
  $res->nameservers('0.0.0.0');
  $res->options('debug');
  print $res->as_string;

METHODS

new([$filename])

Returns a reference to a new Net::Bind::Resolv object. If $filename is given then use that pass the value to a call to read_from_file.

read_from_string($string)

Populates the object with the parsed contents of $string. Returns 1 is no errors were encounters, otherwise it returns 0.

The following directives are understood.

• domain DOMAIN

• search SEARCHLIST...

  If a search directive and domain directive are found in the same file, the last one encountered will be recorded and all previous ones will be ignored.

• nameserver IP_ADDR

  Each instance of a nameserver directive will cause the given IP_ADDR to be remembered.

• sortlist SORTLIST...

• options OPTIONS...

There are very few requirements placed on the data in $string. Multiple entries of certain directives, while technically incorrect, will cause the last occurrence of the given directive to be the one remembered. If there is sufficient precedence for this to be otherwise, let me know.

There is no requirement for the arguments to the directives to be valid pieces of data. That job is delagated to local policy methods to be applied against the object.

read_from_file($filename)

Populates the object with the parsed contents of $filename. This really just a wrapper around read_from_string. Returns 0 if errors were encountered, otherwise it returns 1.

clear

Zeros out the internal data in the object. This needs to be done if multiple read_from_string methods are called on a given Net::Bind::Resolv object and you do not want to retain the previous values in the object.

domain([$domain])

Returns the value of the domain directive. If $domain is specified, then set the domain to the given value and the searchlist, if defined in the object, is undefined.

nameservers([@values])

Returns (in order) the list of nameserver entries. If called in an array context it returns an array, otherwise it returns an array reference.

If @values is specified, then set the nameserver list to the given values. Any items in @values that are list references are dereferences as they are added.

searchlist([@values])

Returns an array reference containing the items for the search directive. If called in an array context it returns an array, otherwise it returns an array reference.

If a list of values is specified, then set the searchlist to those values and the domain, if defined in the object, is undefined. Any items in @values that are list references are dereferenced as they are added.

sortlist([@values])

Returns an array reference containing the items for the sortlist directive. If called in an array context it returns an array, otherwise it returns an array reference.

If a list of values is specified, then set the sortlist to those values. Any items in @values that are list references are dereferenced as they are added.

options([@values])

Returns the items for the options directive. If called in an array context it returns an array, otherwise it returns an array reference.

If a list of values is specified, then set the options to those values. Any items in @values that are list references are dereferenced as they are added.

comments([@strings])

Returns the comments for the object. If called in an array context it returns an array, otherwise it returns an array reference.

If a list of strings is specified, then set the comments to those values after splitting the items on a NEWLINE boundary. This allows several combinations of arrays, array refs, or strings with embedded newlines to be specified. There is no need to prefix any of the comment lines with a comment character ([;\#]); the as_string automagically commentifies (:-) the comment strings.

Any items in @strings that are list references are dereferenced as they are added.

as_string

Returns a string representing the contents of the object. Technically, this string could be used to populate a resolv.conf file, but use print for that. The <print> method is a wrapper around this method. The data is generated in the following order:

  comments
  domain        (mutually exclusive with search)
  search        (mutually exclusive with domain)
  nameservers   (one line for each nameserver entry)
  sortlist
  options

print($fh)

A wrapper around as_string that prints a valid resolver(5) representation of the data in the object to the given filehandle.

check([$policy])

Performs a policy/validity check of the data contained in the object using the given subroutine &policy. The given $policy routine is called as &$policy($self). If $policy is not given it defaults to using default_policy_check. It returns the return status of the policy check routine.

default_policy_check

A simple wrapper around various check_* methods.

check_domain

Returns 1 if the domain member of the object is defined and is a valid rfc1035 domain name, otherwise returns 0.

check_searchlist

Returns 1 if the searchlist member of the object is defined and contains only valid rfc1035 domain names, otherwise returns 0.

check_nameservers

Returns 1 if the nameservers member of the object is defined and contains only ip-addresses, otherwise returns 0.

Uses valid_ip to do the real work.

check_sortlist

Returns 1 if the sortlist member of the object is defined and contains only ip-address/netmasks, otherwise returns 0.

Uses valid_netmask to do the real work.

check_options

Returns 1 if the options member of the object is empty or contains only valid options, otherwise returns 0.

Currently recognized options are:

• debug

• ndots:N

qtynameservers

Returns the quantity of nameserver entries present.

CAVEATS

The read_from_{file|string} methods and the print method are not isomorphic. Given an arbitrary file or string which is read in, the output of print is not guaranteed to be an exact duplicate of the original file. In the special case of files that are generated with this module, the results will be isomorphic, assuming no modifications were made to the data between when it was read in and subsequently written back out.

Since Net::Bind::Resolv does not impose many requirements on the values of the various directives present in a /etc/resolv.conf file, it is important to apply the appropriate policy methods against the object before writing it to a file that will be used by the resolver. Consider yourself warned!

AUTHOR

Kevin Johnson <kjj@pobox.com>

COPYRIGHT

Copyright (c) 1997 Kevin Johnson <kjj@pobox.com>.

All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

cpanm Net::Bind

perl -MCPAN -e shell
install Net::Bind